GOST 26258-87 Cylindrical counterbores for processing supporting surfaces for fasteners. Specifications

Metal counterbore is used for secondary processing of holes in industrial equipment structures. This allows you to obtain a support or contact area with high mating accuracy. Treated holes are used for mounting various fasteners: bolts, screws or studs. Reliable fastening of structural elements is the basis for high-quality assembly, therefore countersinking is used in all industries with high technological requirements for the production process.

Getting holes

In order to thoroughly understand what countersinking is, you need to have an idea of ​​how holes are made in parts.
Let's say it is necessary to drill a hole of the fifth accuracy class with a diameter of 12 mm in a workpiece. An important indicator that affects the maximum and minimum values ​​is the required quality. For example, it is necessary to finish countersinking a hole with a diameter of 85 mm with grade H11. Based on the tables of tolerance fields for holes with nominal sizes from 1 to 500 mm, for quality 11 (for diameters from 80 mm to 120 mm) the tolerance field is: the upper value is “+220”, and the lower value is “0”, that is, 85 +220 mm. The maximum diameter of the drilled hole cannot exceed 85.22 mm, and the minimum - 85 mm.

In this case, the size tolerance is the difference between D max and D min, that is, it will be 0.22 mm. If we talk about defects, then for a hole a diameter above the value of 85.22 mm will be considered irreparable, and a diameter less than 85 mm will be considered reparable.

A countersink is a metal-cutting tool with several working blades, designed for processing pre-drilled holes of cylindrical or conical shape. Using a countersink, when choosing the required type of tool, you can obtain recesses of different configurations in the holes of the workpieces. Countersinking should not be confused with countersinking, drilling holes to their full length to improve the quality of the surface.

GOST 21.502-2016 SPDS. Rules for the execution of working documentation for metal structures

This GOST establishes the composition and rules for the execution of working documentation for building metal structures, drawings of the KM brand, but does not apply to the execution of detail drawings of metal structures of the KMD brand.

Requirements for components of metal structures are given in section 6.5 of GOST 21.502.

6.5.1 The drawings of components of metal structures show fundamental solutions that ensure the operation of the design diagram of a building or structure.

6.5.2 Drawings of assemblies depict elements of metal structures converging in an assembly, indicating references to coordination axes, axes of elements, surfaces of parts, marks of the top or bottom of structural elements.

An example of a drawing of a metal structure assembly is shown in Figure K.1 (Appendix K).

Figure K.1 - Example of a drawing of a metal structure assembly

6.5.3 The drawings of the units depict adjacent structural elements that are not developed in these working drawings of the KM brand, indicating their sizes, connections and other requirements necessary for the development of detail drawings of the KMD brand.

Drawings of the simplest structural units that do not require explanation are developed in detail drawings of the KMD brand.

6.5.4 The drawings of the units indicate:

• values ​​of forces acting in the elements (if they are not specified in the list of elements);
• bindings to coordination axes;
• thickness of parts;
• dimensions of welds;
• types, strength classes, number, diameters and pitches of bolts or other fasteners;
• requirements for processed surfaces;
• sections, names and grades of metal of parts not specified in the list of elements;
• technical requirements.

Note - The thickness of parts, dimensions of welds, number, pitches and strength class of bolts or other fasteners are not indicated if they can be determined during the development of detail drawings of the KMD grade.

Scope of application

The counterbore belongs to the same group of tools as the countersink. It is intended to create recesses and improve the quality of the end surfaces of holes in metal products. It is installed mainly on drilling machines, but can also work on turning and milling machines. The tool is a type of counterbore, thereby clarifying the definition of a counterbore and understanding what it is and what it is used for.

The cutting edges of the tool are located at the end of the counterbore working area, along the perimeter of the rotating shaft. At the very end there is a guide pin, which is inserted into the drilled hole, thus aligning its axis with the axis of the tool.

The tasks of the counterbore are as follows:

• obtaining a strictly perpendicular reference plane around the hole for better contact between it and the fastener;
• alignment of the internal end elements of the part;
• removal of burrs and sagging;
• chamfering.

It can be seen that end countersinks provide the dimensional accuracy of metal products required by modern standards and create the conditions necessary for high-quality assembly. And also, if necessary, they process the ends of embedded products.

Purpose of the tool

The principle of operation of the counterbore is similar to the operation of another processing tool - a countersink.

A countersink is designed to expand finished round holes by cutting with tool blades. In this case, the thickness of the removed metal layer is small.

Countering is very rarely used manually due to the low accuracy of this processing method. Depending on the nature of the work, it is installed on the following machines:

• drilling;
• milling;
• boring;
• turning

The tool is most widely used as a processing tool on drilling-type machines.

The sharp elements of the counterbore are located in the end part. They are evenly distributed around the perimeter of the main shaft, which rotates around its axis. This design caused the spread of the tool for use on drilling rigs.

Countering metal can pursue the following purposes:

• obtaining a perfectly flat reference plane located at an angle of 90° relative to the hole;
• elimination of defects in the inner surface of holes;
• chamfering an edge;
• grinding of sagging and burrs of metal;
• creating multi-stage holes.

The tool has no requirements for the material of the workpiece. It copes equally well with all types of ferrous and non-ferrous metals, as well as alloys based on them.

The accuracy of work meets modern standards used in the production of precision engineering parts up to accuracy class 2.

Question answer

How to determine the optimal cutting speed?

The cutting speed is selected taking into account the tool diameter and rotation speed. It is necessary to introduce correction factors. The obtained data can be used to calculate the spindle speed.

How to determine the depth of cut with a counterbore?

This indicator is calculated as half the diameter of the cutting tool minus the diameter of the rough hole.

Is it possible to make custom-made counterbores?

Yes, we will produce tools according to your drawings in a period of 5 to 45 days.

A. The center has a lower smooth guide part that is inserted into the hole around which the processing is performed, which makes it possible to maintain the mutual perpendicularity of the resulting surface and the axis of the hole.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978. Synonyms

:

See what “Tsevka” is in other dictionaries:

• Countersink for cleaning end surfaces. Typically, counterbores are made in the form of mounted heads with end teeth. Counters are used to process bosses for washers, thrust rings, and nuts. See also: Cutting tools Financial Dictionary... ... Financial Dictionary

Countersinking, countersinking, countersink Dictionary of Russian synonyms. countersink noun, number of synonyms: 4 countersink (2) countersink ... Dictionary of synonyms

counterbore

- NDP. face countersink face countersink trimming Axial multi-edge tool for processing the cylindrical and (or) end section of a workpiece hole. Inadmissible, not recommended trimming... ... Technical Translator's Guide

counterbore

- tsek ovka, and, genus. p.m. h. wok ... Russian spelling dictionary

Countering

— Countersink for cleaning end surfaces (for example, removing bosses). As a rule, it is made in the form of mounted heads with end teeth ... Builder's Dictionary

Countering, processing around the hole of a part to obtain a plane, conical. or cylindrical recesses for a screw head or nut, Dir. special tool countersink (counterbore) ... Big Encyclopedic Polytechnic Dictionary

Countersink, countersink, countersink Dictionary of Russian synonyms. countersink noun, number of synonyms: 2 tool (541) ... Dictionary of synonyms

A production tool for changing the shape and size of a processed metal workpiece by removing part of the material in the form of chips in order to obtain a finished part or semi-finished product. There are machine and manual M. and. Main parts... ...

Treatment of the surface of a part around a hole (a type of countersinking (See countersinking)), intended to form planes or recesses for a screw head, washer, thrust ring, etc. C. is produced on drilling machines, ... ... Great Soviet Encyclopedia

This article should be Wikified. Please format it according to the article formatting rules. Drilling is a type of mechanical processing of materials by cutting, in which using a special rotating cutting tool (drill ... Wikipedia

A counterbore or countersink is a type of metal-cutting tool designed for making cylindrical holes and chamfering holes. Can be used to work on steels, non-ferrous metals, hard alloys.

Countersink

What is the difference between countersinking and countersinking? Although they sound similar, they are different operations. Each has its own purpose and a specific tool for execution.

• cylindrical, used to make cylindrical recesses at the top of the hole to hide the heads of screws or nuts;
• conical, with their help they cut out a cone-shaped recess in the lower part of the hole, chamfer and form recesses for fasteners.
• end, also called counterbore, such a tool is needed for cleaning out recesses before installing fasteners.

Structurally, the countersink consists of two parts: the working head and the shank. A guide pin is provided on the shank, ensuring alignment of the selected recesses.

A drilling machine is usually used as equipment along with countersinks. Less commonly, they are clamped into the chuck of a multi-axis machining center or a simple lathe. Drills and other hand-held drilling tools are not recommended for use as they cannot provide proper alignment and accuracy.

Countersinking is the processing of the inner surface of a hole to improve its quality.

• accuracy;
• roughness;
• forms.

Countersinking is used to process holes made by drilling, stamping or casting. A countersink is used to perform the operation. It resembles a drill, but differs from it in the following ways:

• a large number of cutting edges;
• thickened bridge between edges;
• beveled corner.

These design features determine the stability of the position of the countersink relative to the hole and their coaxiality. The countersink does not deepen the hole, but only improves the smoothness and shape of the surface, removing a very thin layer of material.

Countersinks have from six to eight cutting edges; small diameter tools (up to 20 mm) are made in one piece, while larger ones have inserted blades.

What is a counterbore and why is it needed?

From a technical point of view, it is a cylindrical axial type tool, in which the cutting elements are located at the back of the end of the tool. There are usually deep grooves on the sides of the counterbore - with their help, chips are quickly removed. For reliability, the counterbore is fixed using a pin - it ensures precise perpendicular direction of the working tool, which has a beneficial effect on the processing accuracy.

The counterbore can be installed on industrial and hand drills, on lathes, and on various metal-cutting equipment

Please note that there is an element in the form of a tail located at the back - it ensures reliable fixation of the tool on the metal-cutting tool, which has a beneficial effect on cutting accuracy

With a counterbore, all the cutting elements are located behind the axial part - therefore it is impossible to drill with such a tool. In what areas of activity then can this tool be used and what technological problems can it solve?

Application

• Processing of various standard type holes located on reference planes. These holes are for fastening elements using bolts, screws, washers, and special fixing rings.
• Final processing of the ends of various metal elements (metal forging in this case is needed to clean surfaces, eliminate minor irregularities and defects associated either with the heterogeneous structure of the metal itself, or with poor quality initial processing).

All manipulations that can be performed using counterbore are called the general term counterbore. The best way to counterbore is to level the uneven metal surface next to the hole. This treatment has a beneficial effect not only on the appearance, but also on the physical and operational properties of the part.

In most cases, metal counterbore is used for processing steel and alloys. If necessary, it can be adapted for processing any non-ferrous and precious metals - copper, aluminum, lead, silver, gold + various alloys.

Washers - guests, designations

Washers are used to protect the surface of the part from damage by the nut when tightening the latter and to increase the bearing area of ​​the nut, bolt head or screw, to eliminate the possibility of the nuts self-unscrewing when they experience vibrations, temperature changes in other cases. There are round washers (Fig. 8.57, a), square (Fig. 8.57, b), spring washers (representing a turn of a screw protrusion in the left direction) (Fig. 8.58), multi-claw (Fig. 8.59), locking, spherical, eliminating pin misalignment or a bolt when changing the position of parts of connected parts (Fig. 8.60), quick-release (Fig. 8.61), oblique (Fig. 8.62) for leveling the slopes of channel flanges and I-beams, etc.

Washers are made by cutting from sheet material (metal, leather, rubber, plastic) or by turning from bar metal, in particular calibrated.

Examples of designations: Washer A.12.01.08kp.016 GOST 11371-78 (Fig. 8.57, a), where version 1 (not indicated), for a fastener with a thread diameter of 12 mm, with a thickness established by the standard, made of steel grade 08kp (indicated for groups 01, 02, 11, 32, since each of them contains two grades of steel); 016 - coating. The same, version 2 (accuracy class A): Washer 2.12.01.08kp. 016 GOST 11371-78. The actual diameter of the hole in the washers is slightly larger than that indicated in the designation by 0.5...2 mm, depending on the thread diameter.

Multi-claw washers are designated similarly (they have one design each): Washer 64.02. StZ.016 GOST 11872-89 (see Fig. 8.59), where 64 is the thread diameter of the round spline nut, 02 is the material group. An example of the designation of a quick-release washer (see Fig. 8.61): Washer 5.03.016 GOST 11648-75, where 5 is the diameter d of the hole, consistent with the diameter d1 of the groove on the shaft. Spring washers (see Fig. 8.58) are produced in four types: light (L), normal (N), heavy (T); especially severe (OT). Example of designation: Washer 12 65G GOST 6402-70, where 12 is the thread diameter of the fastener, 65G is the steel grade (spring manganese). Version 1 is not written, the washer is of normal type (the letter H is not indicated), without coating. An entry in the designation, for example, 12T, will identify a heavy-duty washer. In Fig. 8.58, a - spring washer version 2. Washers of the type shown in Fig. 8.57, b, designate: Washer 6 GOST 24197-80, where b is the diameter of the hole. The material is not specified, since it is provided for by the standard (StZpk according to GOST 380-71**). When using mild steel, the letter C is placed after the hole diameter size, for example 6C. In training drawings it is usually assumed that the washers are not coated. GOST 6402-70* has been supplemented with data on spring washers of version 2.

GOST R 21.1101-2013 SPDS. Basic requirements for design and working documentation

This GOST establishes the basic requirements for design and working documentation for the construction of facilities for various purposes.

Requirements for units and sections are specified in section 5.5 of GOST R 21.1101-2013.

In accordance with clause 5.5.2, sections of a building or structure are designated in Arabic numerals sequentially within the graphic document.

Independent numbering is allowed for sections of individual sections of a building, structure or installation, all drawings of which are placed on one sheet or group of sheets and if these drawings do not contain references to sections located on other sheets of the graphic document.

It is allowed to designate sections in uppercase or lowercase letters of the Russian alphabet (with the exception of the letters specified in 5.3.2).

According to clause 5.3.2 ....except for the letters: Ё, З, И, О, ​​X, Ц, Ш, Ш, Ъ, ы, ь) or, if necessary, letters of the Latin alphabet (except for the letters I and O) .

The position of the cutting plane is indicated in the drawing by a section line (open line according to GOST 2.303). In case of a complex cut, strokes are also made at the intersection of the cutting planes. Arrows should be placed on the initial and final strokes indicating the direction of view; arrows should be applied at a distance of 2-3 mm from the end of the stroke (Figure 10).

Figure 10

The direction of view for a section according to the plan of a building and structure is, as a rule, taken from bottom to top and from right to left.

In accordance with table 1 GOST 2.303-68 “Unified system of design documentation (ESKD). Lines"

clause 5 of GOST 2.303 The thickness of the solid main line should be in the range from 0.5 to 1.4 mm, depending on the size and complexity of the image, as well as on the format of the drawing.

The thickness of lines of the same type should be the same for all images in a given drawing, drawn to the same scale.

clause 5.5.3 GOST R 21.1101-2013 If individual parts of the view (façade), plan, section require a more detailed image, then additionally local views and remote elements - nodes and fragments - are performed.

5.5.4 In the image (plan, facade or section) from which the node is taken out, the corresponding place is marked with a closed solid thin line (circle, oval or rectangle with rounded corners) with the designation of the node in Arabic numeral on the shelf leader line in accordance with Figures 11a , 11b or a capital letter of the Russian alphabet in accordance with Figure 11c.

Figure 11

If necessary, references to a unit placed in another graphic document (for example, the main set of working drawings), or to working drawings of a typical construction unit, indicate the designation and sheet number of the corresponding document in accordance with Figure 11b or a series of working drawings of standard units and the issue number in accordance with Figure 11c.

If necessary, a link to a node in a section is made in accordance with Figure 12.

Figure 12

Above the image of the node, its designation is indicated in a circle in accordance with Figure 13a, if the node is depicted on the same sheet from which it is taken, or 13b, if it is placed on another sheet.

Figure 13

A node that is a complete mirror image of another (main) design is assigned the same designation as the main design, with the addition of the index “n”.

5.5.5 Local species are designated in capital letters of the Russian alphabet, which are placed next to the arrow indicating the direction of view. The same designations are applied above the images of species.

5.5.6 For each type of images (sections and sections, nodes, fragments), an independent numbering order or letter designations are used.

5.5.9 If the image of a section, section, node, view or fragment is placed on another sheet, then after the designation of the image indicate in brackets the number of this sheet in accordance with Figures 10, 11a, 12 and 14.

According to clause 5.5.14, the names of sections are digital or letter designations of cutting planes.

Example - 5-5, B-B, a-a

Varieties

Steady rests are divided according to various factors: dimensions, methods of fastening the product on a lathe, additional structural elements, weight, number of fasteners.

Fixed rest

A fixed steady rest is used to hold long parts. The part is secured to the equipment using mounting bolts that are screwed into the support plate.

The peculiarity of fixed structures is that it has three cams, one of which supports the top, the other two - the bottom. For fastening to workpieces, the fixed steady rest has a folding hinge, which simplifies this process.

Movable steady rest

The moving parts have several differences from the previous ones. The lathe has a longitudinal support on which the steady rests are attached. Thanks to this, the movement of the cutters with the additional part occurs simultaneously. This allows for more uniform processing. The cutting tool does not jam and maintains its integrity for a long period of time.

Another feature of the moving part is the presence of two cams to stop the part. One is located on the top of the structure, the other on the side. The role of the third stop is performed by the cutter.

Movable steady rest on the machine

APP (recommended). CONSTRUCTION ELEMENTS AND GEOMETRICAL PARAMETERS OF COMBININGS

APPENDIX Recommended

Damn.8. Type 1

Type 1

(Figure 8, Table 10)

Damn.8

Table 10

mm

Damn.9. Type 2

Type 2

(Figure 9, Table 11)

Damn.9

Table 11

mm

Damn 10. Type 3

Type 3

(Figure 10, Table 12)

Damn.10

Figure 10 (continued)

Table 12

mm

TYPES AND MAIN SIZES

1. TYPES AND MAIN DIMENSIONS

1.1. Counterbodies must be manufactured of the following types:

1 - with a permanent guide pin and a cylindrical shank;

2 - with a replaceable guide pin and a conical shank;

3 - mounted with a replaceable guide pin;

4 - with a replaceable guide pin and a shank for a pin lock. Counterbodies types 2-4 are manufactured in two versions:

1 — counterbores with a working part made of high-speed steel;

2 - counterbores with a working part equipped with carbide plates. Type 1 counterbores are manufactured only in the 1st version.

1.2. Counters with a working part made of high-speed steel are designed for processing structural steel, with a working part equipped with carbide inserts for processing structural steel and cast iron.

1.3. The design and main dimensions of the bores must correspond to those indicated in Figure 1 and Table 1 for bores of type 1; in drawings 2, 3 and in table 2 for counterbores of type 2; in drawings 4, 5 and in table 3 for counterbores of type 3; in drawings 6, 7 and in table 4 for counterbores of type 4.

Damn.1. Type 1. Counterbore with constant guide pin and cylindrical shank

Type 1
Counterbore with permanent guide pin and cylindrical shank
Fig.1

Table 1

mm

An example of a symbol for a type 1 counterbore with a diameter of the working part = 5.0 mm, a diameter of the guide pin = 2.0 mm:

Counterbore 2350-0636 GOST 26258-87

Damn.2. Type 2. Counterbore with replaceable guide pin and tapered shank

Type 2
Counterbore with replaceable guide pin and tapered shank
________________ * Dimensions for reference. ** It is allowed to position the screw axis (pos. 3) perpendicular to the supporting plane of the guide pin shank (pos. 2).

1 — counterbore; 2 — guide pin type 1 according to GOST 26259-87; 3 — screw according to GOST 1477-84; 4 - carbide plate according to GOST 25400-82 Drawing 2

1.4. The design and main dimensions of the counterbores (item 1) must correspond to those indicated in Figure 3 and Table 2.

Damn.3. Design and main dimensions of the counterbores (item 1)

Damn.3

table 2

mm

An example of a symbol for a counterbore type 2, execution 1, diameter = 13.5 mm:

Counterbore 2350-0706 GOST 26258-87

The same, version 2 with plates made of hard alloy grade VK8:

Counterbore 2350-0707 VK8 GOST 26258-87

Damn.4. Type 3. Counterbore with replaceable guide pin mounted

Type 3 Counterbore with replaceable guide pin, mounted

________________ * Size for reference.

1 — counterbore; 2 — guide pin type 1 according to GOST 26259-87; 3 — mandrel according to GOST 26260-84; 4 — screw according to GOST 1477-84; 5 - carbide plate according to GOST 25400-82 Drawing 4

1.5. The design and main dimensions of the counterbores (item 1) must correspond to those indicated in Figure 5 and Table 3.

Damn.5. Design and main dimensions of the counterbores (item 1)

Damn.5

Table 3

mm

An example of a symbol for a counterbore type 3, version 1, with a diameter of =53 mm:

Counterbore 2350-0782 GOST 26258-87

The same, version 2 with plates made of hard alloy VK8:

Counterbore 2350-0783 VK8 GOST 26258-87

Damn.6. Type 4. Counterbore with replaceable guide pin and shank for pin lock

Type 4
Counterbore with replaceable guide pin and shank for pin lock
________________ * Dimensions for reference.

1 — counterbore; 2 — guide pin type 2 according to GOST 26259-87; 3 — nut according to GOST 5915-70; 4 - carbide plate according to GOST 25400-82 Drawing 6

1.6. The design and main dimensions of the counterbores (item 1) must correspond to those indicated in Figure 7 and Table 4.

Damn.7. Design and main dimensions of the counterbores (item 1)

Damn.7

Table 4

mm

An example of a symbol for a counterbore type 4, version 1, diameter = 13.5 mm:

Counterbore 2350-0793 GOST 26258-87

The same, version 2 with plates made of hard alloy grade VK8:

Counterbore 2350-0794 VK8 GOST 26258-87

1.7. Center holes - form A according to GOST 14034-74. For type 1 counterbores with trunnion and shank diameters less than 6 mm, outer centers with an angle of 75° are allowed.

1.8. The dimensions of Morse cones are according to GOST 25557-82. Tolerances of Morse cones are AT 8 according to GOST 2848-75.

1.9. The dimensions of the keyway are in accordance with GOST 9472-83.

1.10. The dimensions of shanks for pin locks are in accordance with GOST 3009-78.

1.11. Metric thread - according to GOST 24705-81. Tolerances of external thread 8q, internal thread 7N - according to GOST 16093-81.

1.12. Structural elements, geometric parameters of counterbores and designation of plates are given in the recommended appendix.

countersinks

Countersinks (Fig. 3.34, a) are designed for processing holes in workpieces obtained by casting, stamping or pre-drilling. Unlike a drill, a countersink has a larger number of cutting edges (three or four), which ensures surfaces with higher accuracy and roughness. By design, countersinks are mounted and solid and can have a different direction of the spiral angle (right, left, straight). Countersinks are made of high-speed steel or equipped with plates made of hard alloy grades VK6, VK8, BKbM, VK8V, T5K10, T15K6. Carbide plates are fixed in the countersink using soldering or wedge fastening, which allows the countersink body to be reused. The working part of countersinks made of high-speed steel has a reverse taper (towards the shank) of the order of 0.05... 0.1 per 100 mm of the length of the working part and is connected to the shank in the same way as with drills, by a neck. Solid countersinks are fixed directly in the conical hole of the machine spindle, and attachment ones are installed on a special mandrel, which also has a conical shank for installation in the machine spindle.

Multifaceted carbide plates are used as the cutting part of mounted countersinks. The fastening of such plates in the body of the mounted countersink is carried out mechanically (Fig. 3.35). The cutting plates 1 are fixed in the housing 2 using a rod 3, which makes it possible to replace the plates directly on the machine. To do this, it is enough to move the rod 3, rotate the plate with the next edge or replace it with a new one, fasten the rod again and continue working. The ability to equip such countersinks with plates made of various tool materials can significantly expand the technological capabilities and productivity during countersinking.

The geometric parameters of the cutting part of the countersinks (see Fig. 3.34, b) are selected depending on the processing conditions: leading angle f = 30... 60 rake angle y = 3... 30 ° for countersinks made of high-speed steel, for countersinks equipped with hard plates alloy, this angle ranges from 5 to -5°; clearance angle a on the main cutting edges is 8... 15 The choice of countersink design and material of the working part largely depends on the material being processed and the parameters of the hole being machined:

• countersinks made of high-speed steel, having three to four teeth and a diameter of 10 to 40 mm, are used for machining holes in workpieces made of structural steel;

• countersinks equipped with hard alloy plates, having three to four teeth and a nominal diameter of 14 to 50 mm, are used when machining holes in workpieces made of difficult-to-cut and hardened steels;

• countersinks with mounted heads made of high-speed steel with a nominal diameter from 32 to 80 mm are designed for processing holes in workpieces made of structural steel;

• countersinks are used for processing blind holes in workpieces made of cast iron and non-ferrous metals;

• for processing blind holes with a diameter of 15 to 25 mm, a special countersink is used, in which a special hole is made in the body for supplying coolant to the cutting zone (Fig. 3.36).

Wear of countersinks (Fig. 3.37) occurs along the rear surfaces, where areas with a rear angle equal to zero and width h3 are formed; along the front surfaces with the formation of a hole; along the ribbon with the formation of transverse grooves along the length Ll; along the corners to form conical or cylindrical sections hy. As a criterion for wear of countersinks when processing steel workpieces, the wear of the countersink at the corners is equal to 1.2 ... 1.5 mm, and when processing workpieces made of cast iron - 0.8 ... 1.5 mm. Sharpening and regrinding of worn-out countersinks is carried out, as a rule, on special equipment in sharpening shops.

Basic technical requirements for the manufacture of counterbores

According to GOST 26258, attachment tools, as well as tools with a working part with a diameter of up to 8 mm and a cylindrical shank, are manufactured in one piece. Counters with a working part, the diameter of which is over 8 mm, and a cylindrical shank, as well as with a locking and conical shank, are made welded. Cracks and arson should not be allowed at the welding site, and oxidation, fistulas and pores should not be allowed in the welding seam.

The body along the chipping part of the screw grooves and the shank of all counterbores are made of steel 45Х, 40Х (GOST 4543) or 45 (GOST 1050). Depending on the design of the tool, the material of its working part will be as follows:

• The 1st version of the counterbore has a cutting part and ridges of helical grooves made of high-speed steel, manufactured in accordance with GOST 19265.
• For the 2nd version - the material of the cutting part is one of the following grades of hard alloy according to GOST 3882: T15K6, T5K10, VK6M, VK6. Dimensions and shape of carbide plates according to GOST 25400.

To attach carbide plates to the working part, MNMts 68-4-2 alloy or L68 or L63 brass (GOST 15527) should be used as solder. When soldering, a layer of solder up to 0.2 mm thick should be formed.

All surfaces of the tool should be free of traces of corrosion, burrs, cracks and shells, polished surfaces should be free of rough surfaces, and the cutting part should be free of burns and chips. After heat treatment of the counterbore, its center holes should not have developed areas or nicks.

The reverse taper of the edges of the working part of the tool should be uniform: for counterbores of the 2nd design along the length of the carbide inserts, and for the 1st design - along the working part. The value of the reverse taper of a tool with a working part made of high-speed steel should not exceed the values ​​of 0.08–0.16 mm per 100 mm of length, and those equipped with carbide inserts – 0.05–0.10 mm per plate size.

Requirements of state standards for the manufacture of counterbores

Requirements for the production of countersinks are determined by GOST 26258-87. Thus, according to this document, a tool of the attachment type, as well as one whose working part has a diameter of no more than 8 mm and whose shank has a cylindrical shape, is produced in one piece. Tools with a cutting diameter greater than 8 mm, with all types of shanks, must have a welded construction. High demands are placed on the quality of the welds used to make such a tool. In these seams, the presence of cracks and burns is excluded; they should not contain traces of oxidation, tubular cavities and pores.

The main rod of the counterbores, including the shank, is made of steel grades 45, 40 X or 45 X. The following materials can be used for the cutting part.

• Tools that are entirely made of high-speed steel are made of material, the requirements for which are specified by the provisions of GOST 19265.
• Materials for the cutting part of counterbores with carbide inserts can be VK6, VK6M, T5K10, T15K6. Requirements for the material characteristics of such plates are specified in GOST 3882, and for their geometric shape and dimensions - in GOST 25400.

Carbide plates on the working part of the tool are fixed using solder grades MNMts 68-4-2, brass grades L63 or L68. The thickness of the solder should be at least two tenths of a millimeter.

Material of counterbores with carbide inserts

Like the surface of drills, cutters and other metal-cutting tools, the surface of counterbores must be free of defects - traces of corrosion, cracks, voids and burrs. Cracks and tears are not allowed on the polished part, and chips and burns are not allowed on the working part. The center holes of the counterbores after quenching and tempering should not have recesses or developed areas.

Such a geometric parameter of counterbore as reverse taper (reducing the diameter towards the shank) must be uniform along the entire length of the working surface (for tools made of high-speed steel), along the entire height of the cutting inserts (for tools with carbide tips). Tolerances for this parameter, according to the drawing and the requirements of the regulatory document, should be no more than 0.08–0.16 mm per 100 mm of the length of the working part for counterbores made of high-speed steel, and 0.05–0 for counterbores with tipped carbide. 1 mm for the entire plate size.

Design

The conical countersink consists of two main elements - the working part and the shank. The working part has a cone with a standard range of angles at the apex from 60 to 120°. The number of cutting blades depends on the diameter of the tool and can be from 6 to 12 pieces.

A cylindrical countersink is similar in design to a drill, but has more cutting elements. At the end there is a guide pin necessary for fixing the position of the tool during processing. The limiter can be removable or be part of the body of the instrument. The first option is more practical, as it expands processing capabilities. A cutting attachment can also be installed.

If it is necessary to drill several holes to equal depths, a tool with holders with a rotating or fixed stop is used. Before processing, the countersink is fixed in the holder so that the cutting part protrudes from the stop at a distance equal to the required depth of hole processing.

The tool is made from tool alloy, carbon, high-speed and carbide steel grades. For processing cast iron parts, carbide steels are most often used; for ordinary steels, high-speed and tool steels are used.

Follow the rules when working with a counterbore

When performing counterboring, you must adhere to a number of rules:

• When counterboring open surfaces, it is recommended to fix a stop on the tool shank. The simplest method is to use a thrust nut with a lock nut.
• When counterboring recesses for hardware heads, a tool with a vertex angle of 90° is used. Reducing the angle is carried out in cases where, after counterboring, a cut remains on the surface of the hole being machined.
• Making holes for hardware is carried out in two stages. First, a hole is drilled to a certain diameter, then the hole is given the desired shape and size by counterbore.
• The counterbore guide should not be in full contact with the bushing. Contact with screw strips is acceptable. Violation of this rule can lead to jamming of the counterbore in the bushing as a result of strong heating of the workpiece and metal-cutting tool under the influence of high rotation speed of the machine spindle.
• Hole alignment is ensured through the use of counterbores with guides.
• When securing an end countersink in a quick-change chuck, it is recommended to place the cutting teeth at both ends.
• To process workpieces made of high-hard metals, you should use tools with carbide inserts.
• For processing brittle alloys, it is recommended to use single-tooth screw end countersinks with a radially located front surface.

Compliance with the rules guarantees perfectly accurate sized holes.

Countering operation

The counterbore process is the special processing of complex holes in metal products using counterbore. With the help of counterboring work, it is possible to prepare the armhole before other operations and metalworking processes and improve the quality of the processed internal elements of the metal part. The master makes the counterbore of the holes on the machine in the cutting mode. The process is usually performed at low speed due to its complexity. During the armhole countersinking process, not only the internal hole of the workpiece is counterbored. Also, by countersinking you can align the end elements on the inside of the product, remove sagging and burrs from parts, chamfer edges, form stepped armholes and process recesses of complex configurations.

General rules for working with counterbore

When using counterboring in production, you should adhere to the following recommendations:

• When processing the external planes of parts, the tool tail is fixed with a thrust nut with a pin lock.
• The hole for fastening is made in two passes. First, it is drilled out, leaving a little for subsequent processing, then, removing the excess by countersinking, the required size and shape are obtained.
• When counterboring, the guide pin must have a sufficient difference in size with the hole, otherwise, as a result of thermal expansion of the metal of the part and the tool itself, the counterbore may get stuck.
• When creating recesses to hide the heads of hardware, counterbores with an angle at the top of 90° are used. The angle is reduced when, during processing, a hole defect such as a cut becomes noticeable.
• Countering of hard metals is carried out with a tool with carbide plates.
• When working with brittle metals, special countersinks with one tooth and a radial front surface are used.
• To ensure the alignment of the machined recess and hole, use a tool with a guide pin.

The counterbore can also be used at home, where the same general rules and principles of operation of this tool apply.

Countering a hole: basic rules

Countering a hole is an operation that is carried out on machines with a minimum stroke. The countersinking mode configured on drilling, turning, boring or other metalworking equipment is optimal for operation. In some situations, combined type tools are used, which perform several operations in one approach: drilling, countersinking, countersinking, countersinking, etc. All these processes are part of the drilling operation.

Despite the fact that cutting tools are mainly used on industrial equipment, counterbores are also purchased for home use. When working with such a tool, craftsmen should adhere to several rules.

• When machining open surfaces, secure the stop to the shank using a stop nut and lock nut.
• When counterboring holes for screw and bolt heads, use a tool with a 90-degree point angle. The need to reduce the angle is justified to maintain the cut on the surface of the holes being machined.
• Make indentations in 2 stages. First, drill the hole to the desired diameter, then give it the required shape and size.
• Make sure that the entire surface of the tool guide does not come into contact with the bushing. If this rule is not followed, the metal counterbore will become stuck in the bushing due to the intense heating of the material caused by the rotation of the spindle.

Tool design

Taking apart the general design of the counterbore, it can be imagined as a rod consisting of a tail, working and connecting parts. Through the first, they are clamped in a metalworking machine. The second contains the cutting edges and the axle, and it is the one that is in direct contact with the workpiece. The third simply transmits torque from the production unit to the counterbore working area.

According to GOST 26258-87, the following types of counterbores are manufactured:

• with a cylindrical tail and a permanent guide pin;
• with a conical tail and a replaceable guide pin;
• with a tail for a pin lock and a replaceable guide pin;
• mounted counterbores with a replaceable guide pin.

The shape of the tool shank determines how it is mounted in the machine. Cylindrical ends are inserted directly into the equipment chuck, conical ends use an adapter, a Morse taper, and for tails for a pin lock, the machine must have one.

The configuration of the working part determines the processed diameter of the supporting plane, and what material such a tool can work with. Counterbodies for metal are made of high-speed steel and with carbide inserts. For the manufacture of solid face countersinks with a cylindrical tail, only high-speed steel is used. In other cases, for example in mounted ones, carbide plates can be added. They expand the capabilities of the tool, allowing you to process workpieces not only from ordinary structural steel, but also from cast iron. The inserts are fastened using a thin layer of brass solder or MNMts 68-4-2 alloy. The number of blades varies from two to four. Along the length of the rod in the working area, grooves are cut through which steel shavings are discharged. Also, along the entire length of the working part of the counterbore or the length of the carbide plates, if any, it has a reverse taper with a constant angle of inclination.

When inspecting a tool, identifying signs of corrosion, burrs and cracks anywhere, as well as chips and burns in the working area is considered a reason for rejection.

Countering in different versions and types

In accordance with GOST, countersinks are divided into several types:

1. With permanent journals and cylindrical shanks.
2. With variable journals and conical shank.
3. Mounted, with replaceable pins.
4. With replaceable trunnions and pin-lock shank.

Based on the material of manufacture, the following types are distinguished:

• a tool with a working surface made of high-speed tool steels;
• with a working surface made of carbide steel.

The main structural element of trunnion-type counterbores is the working part with blades and the shank.

The number of blades may vary, but the most common is the three-blade countersink drill.

The tool is secured in the machine chuck cam using a shank. Depending on the type of tool, the shank can be cylindrical or Morse taper.

Counters with a pin allow for better alignment of the hole being machined and the recess for fasteners. The trunnion in such instruments plays the role of a guide. The main purpose of tools with a trunnion is to counterbore the end surfaces of bosses for nuts, washers, and rings.

To remove large metal allowances, two-pronged ones are used. This variety is distinguished by the presence of a small (0.3 mm) displacement relative to the tail and working parts of the tool. Each tooth is sharpened along the back at a certain angle. In this way, a front cutting part is formed with an offset along the axis and a transverse blade with a point. This design made it possible to increase processing accuracy.

GOST 26258-87 defines the important technical requirements for counterbores:

• the working part of the tool is made of tool high-speed steel, the shank is made of steel 45 (GOST 1050-74) or 40X (GOST 4543-71);
• tools with a diameter of less than 8 mm with a cylindrical shank are made in one piece, varieties with a conical shank or models with a diameter of more than 8 mm are welded;
• the cutting part should not have chips, burns, burrs or other defects;
• the reverse taper must be uniform along the entire length of the working part. For counterbores made of tool steels, this figure is 0.08-0.16 mm, for carbide steels - 0.05-0.10 mm per 100 mm of length.

Excerpt characterizing Tsekovka

Princess Marya was at first surprised, then frightened by this question. – ME?... Me?!... Is it hard for me?! - she said. – He has always been cool; and now it’s getting hard, I think,” said Prince Andrei, apparently on purpose to puzzle or test his sister, speaking so easily about his father. “You are good to everyone, Andre, but you have some kind of pride of thought,” said the princess, more following her own train of thought than the course of the conversation, “and this is a great sin.” Is it possible to judge a father? And even if it were possible, what other feeling than veneration could arouse such a person as mon pere? And I am so satisfied and happy with him. I only wish that you all were as happy as I am.

Varieties

The following varieties are produced in Russia:

• With a cylindrical cast or welded tail, which is fastened together with a pin-retainer. This type of part is the most common in production, where the same tools are used for a long time, so the master does not need to fine-tune the tools.
• With a conical tail, which has a movable joint with a pin-lock. If necessary, the journal can be removed and replaced with another one, which allows increasing the processing accuracy. Such counterbores are usually used if very high machining accuracy is required. For example, when working with non-ferrous metals and ductile alloys.
• There are also attachment-type counterbores, with replaceable tails and/or trunnions. They are quite rare, since the first two types of parts almost completely cover all major applications. However, non-standard counterbores can still be found - when processing expensive metals and alloys, where minimal chip yield is required, when working with heavy-duty metals, when working with non-standard tools.

There are also two types of counterbores depending on the type of cutting surfaces:

• Counterbodies made entirely of steel. They have good strength and hardness. All major metal alloys can be cut well, with the exception of heavy-duty steels. They do not require any specific care or inspection and retain their strength for a long time.
• Counterbodies with heavy-duty soldering. They have ultra-high strength, so they cut all metals well, including high-strength alloys. They have a limited lifespan because solderings lose their strength over time. Therefore, it is necessary to periodically inspect it, and if defects are found, it is necessary to replace the part with a new one.

Application of scraper conveyors

The scope of application of the mechanism under consideration is very extensive. Often the mechanism is installed in the following cases:

1. Transportation of rock. An example is the mining industry, in which it is necessary to transport material over long distances or carry out lifting.
2. Acts as a support when moving the plow.

When considering the scope of application of a scraper, do not forget that it is limited. This is due to the fact that the scraper conveyor cannot be used to move fragile materials and parts. This is due to the significant impact that is exerted on the surface.

Description of the design and modification of the tool

The counterbore is considered an axial cutting tool. On one side of the cylindrical body there is a working area with several blades, and on the opposite side there is a shank for mounting in the machine chuck. A special feature of the tool is the location of the working processing edges in the end part. Helical grooves run along the side surface to remove chips from the processing zone.

Counterbore with replaceable pin, diameter 12 mm

Perpedicularity and positioning accuracy during the processing of end surfaces is ensured by a special journal in the cutting zone of the tool.

During the cutting process, the guide pin enters the hole and is tightly fixed in it, ensuring the correct, coaxial position of the tool.

Installation and fixation of the counterbore on the machine is carried out, as with all axial tools, by means of a shank.

Types of counterbores

Countersinks for metal-cutting machines are divided into two large groups: cylindrical and conical.

Countering according to GOST

For conical countersinks, the working head profile angle is 60°, 75°, 90° and 120°. The number of cutting edges depends on the diameter. Counters can be with a cylindrical or conical shank. The conical tool is intended for finishing fasteners and for chamfering. The production of conical countersinks is regulated by GOST 14953-80.

Cylindrical countersinks come with a cylindrical and conical shank. An option is available with a wear-resistant coating of rubbing areas. The intended purpose of such a tool is to process support areas.

In accordance with the standards of GOST 26258-87, which regulates the technology for manufacturing counterbores, cylindrical counterbore tools are divided into the following categories:

• With solid guide pin and cylindrical shank shape.
• With replaceable trunnion and conical shank.
• Mounted design, when the blade head is mounted on a mandrel. The guide pin is replaceable and is also fixed to the mandrel.
• With change of shank and axle. Installation on the machine is carried out using a pin lock.

Types of counterbores

Materials and working attachments

Counterbodies with built-in carbide plates

Counterbodies, with built-in hard alloy plates, allow processing of cast iron of various grades and structural steels. Quick cutter tools only work with steels.

The number of blades on the counterbores depends on the design. A solid tool with a cylindrical end has 2-4 cutting edges. Tools in other categories only have 4 blades.

The method of securing the tool in the machine is influenced by the design of the shank. The counterbore with a cylindrical edge is installed directly into the machine chuck. The tool with a cone is mounted in a mounting hole with a special Morse taper. Installing a counterbore with a pin-type locking mechanism requires a pin lock on the machine.

Types of counterbores

We will describe what the tool looks like, what elements it consists of, and what modifications there are.

Design features (information and drawings)

Countering

- a cylindrical tool of axial type with cutting teeth located in the end part. There are grooves on the side surfaces of the product that are designed to remove metal shavings from the work area.

Image #2:

Types of counterbores

The designation of the counterbore in the drawing is given in GOST 26258-87. The same regulatory document defines the technological features of the production of cutting tools and divides them into categories. According to the classification, the following are produced:

• counterbores with cylindrical shanks and guide pins, which are integral with the tool;

tools with conical shanks and removable trunnions;

attachment-type products in the form of cutting heads (put on frames with conical shanks, the axle is replaceable);

tools with replaceable trunnions and shanks, which are mounted in pin locks of machines.

Image #3:

The working parts of the instruments are manufactured:

• entirely made of high-speed steel;

with carbide tipped.

Counterbodies for metal have a different number of working blades. Products with cylindrical shanks are equipped with two to four blades. All other varieties - four.

The type of shank affects how exactly the tool is fixed in the machine.

• Counters with cylindrical shanks are installed in chucks.

Tools with conical shanks are mounted in mounting holes, Morse tapers.

Products with shanks for fastening in pin locks are used together with machines equipped with these fittings.

Requirements for the production of counterbores according to GOST

Requirements for the manufacture of counterbores are regulated by GOST 26258-87. This document indicates that attachment-type tools, the diameters of the working parts of which are less than 8 mm with cylindrical shanks, are produced in one piece. And counterbores with cutting parts larger than 8 mm have a welded structure.

Image #4:

The central rods of the products, as well as the shanks, are made of steel grades 45 and 45X. There are two types of material used for cutting parts.

• High-speed steel - the requirements for it are set out in GOST 19265.

Carbide plates VK6, VK6M, T5K10, T5K6 - requirements for material characteristics are described in GOST 3882, for geometry and dimensions - in GOST 25400.

Image No. 5: Materials that go into the production of counterbores with carbide inserts

Carbide plates are attached to the working parts of the tools with solders of the MNMts 68-4-2 grade and L63 or L68 brass. The minimum solder thickness is 2/10 mm.

The difference between counterbore and other metalworking operations

Countering is a finishing operation that follows after countersinking and in most cases before reaming. The process removes minor flaws from the previous treatment. The specialist removes roughness from the surface of the hole and adds the correct geometry to it. When counterbore, cone-shaped and cylindrical recesses are cut out for the heads of the fastening elements and a flat surface emerges for good contact of the part with them.

The lateral surfaces of the cylindrical recesses for bolts must comply with the dimensions and quality requirements established in the drawings. The process of their processing is called reverse counterbore. It uses countersinks with a very decent number of cutting edges, sometimes their number reaches fourteen.

The parameters set on the machine during processing are calculated and determined according to existing industry standards and product drawings. This includes: feed, depth and cutting speed, productive and required power, as well as an indicator of rationality calculated for the selected operating mode.

Scraper conveyors TSC 50 tons per hour

This version is designed for transporting materials obtained from wood processing. An example is sawdust or wood chips of various fractions. The box is located in a horizontal plane and at an angle of up to 45 degrees. It is possible to install other angles.

A similar mechanism has been used in industry for quite a long period. The first model was already installed in 1988. The material is transported via the upper chute; it is also possible to use the lower chute. In the manufacture of the main part, stainless steel is used, which is coated with paint and varnish to increase the degree of protection. The minimum motor power is 4 kW.

Scraper Rod Conveyor

A special type of scraper conveyor can be called a rod structure. It is widely used in machining shops. Design features include the following:

1. The base is represented by a metal gutter.
2. Inside there is a rod, which is equipped with special spikes.
3. To ensure the fixation of the rod when moving it, special guides are installed.
4. A hydraulic pusher is installed as a drive, making a reciprocating movement.

Key features include simplicity of design, as well as the ability to perform repairs and maintenance yourself. A scraper conveyor is installed in production workshops. Loading areas are covered with hatches with bars. The disadvantage is increased wear, as well as the inability to transport fine substances.

GOST requirements

In Russia, the procedure for manufacturing counterbores is regulated by the state standard GOST 26258-87, as well as some auxiliary regulatory documents (GOST 1050-74, GOST 19265-73 and some others). In accordance with these documents, the following requirements must be taken into account:

Counters with a small diameter (up to 8 mm) have reduced strength, so they require additional operating rules. For such parts, the tail and the trunnion must be made as a single element (that is, the presence of moving parts is not allowed, and even more so, such parts cannot be made collapsible)

Please note that in the case of such parts, welding is also not allowed, since even the highest quality and precise welded connection does not allow obtaining a high-strength part, so a small welded bore will quickly break, which can lead to a decrease in the quality of processing. This will not benefit the holes, which can create an emergency situation. Counterbodies with a diameter of more than 8 millimeters have increased strength

Therefore, their tail and trunnion must be connected by welding. Special ultra-precision welding is used to connect individual elements to each other. The manufacture of counterbores with movable joints without welding is permitted, but it is associated with limitations. Therefore, in practice they are quite rare.

All parts, according to GOST, must have a uniform, smooth surface without cracks or irregularities. If defects are detected, the part is considered defective and withdrawn from circulation.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Machine Tool and Tool Industry of the USSR

PERFORMERS

D.I.Semenchenko, Ph.D. tech. sciences; G.A.Astafieva, Ph.D. tech. sciences; N.I.Minaeva, N.A.Kopteva

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the USSR State Committee on Standards dated November 24, 1987 N 4242

3. Inspection period - 1993, inspection frequency - 5 years

4. INSTEAD GOST 26258-84

5. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

This standard applies to cylindrical counterbores intended for processing supporting surfaces for fasteners in accordance with GOST 12876-67, except for counterbores for enlarged washers for processing supporting surfaces with a diameter of over 61 mm and protruding supporting surfaces with a diameter of up to 15 mm.