Machinery and equipment"Testing of forging and pressing machines"

The general purpose of forging and pressing equipment is to deform metal blanks in order to give them the desired geometric shape. And although, with the help of presses and forging machines, essentially one operation is carried out - metal forming - there is a whole classification of this industrial equipment. The presence of groups and categories of forging and pressing equipment makes it possible for industrial enterprises to select technical means to solve specific production problems.

Devices are classified according to a number of criteria. The main classification characteristics include the following.

1. Workpiece temperature.
2. The value of the main technological parameter.
3. Method of feeding material into the processing zone
4. Type of operations.

Additional criteria for classifying forging equipment are considered to be the control method (manual, semi-automatic, automatic) and the type of energy (electricity, hydraulics, pneumatics).

Type of technological operations

Depending on the type of operations carried out on forging and pressing equipment, machines are divided into blank, main and finishing. The former are used to prepare metal for processing. These are devices that give workpieces a primary geometry, creating the general contours of the finished product. The name of the main forging and pressing machines speaks for itself. They perform metalworking, as a result of which the required product is manufactured. Finishing presses and forging machines are used to carry out operations in the final stages of pressing or forging.

Regarding the auxiliary classification criteria, it should be said that taking them into account when choosing forging and pressing equipment makes it possible to optimize the production of metal products. Here we are talking, first of all, about reducing operating costs. For example, if the production process requires high energy consumption, then it is advisable to use hydraulic machines. And when producing large quantities of similar products, the best results in terms of price and quality ratio are shown by automatic stamping lines.

General information about forging and pressing production

A blanking plant may consist of homogeneous types of metal forming production, for example, forging, pressing, spring production, etc.
Such a plant is called a forging and pressing plant. Procurement plants for heterogeneous production are created as forging and foundry, forging and welding, forging and mechanical, complex (three or more types of production).

A forging plant (centrokuz) is an independent centralized enterprise for the production of forgings for delivery to other (processing) plants directly or through intermediary organizations. Its capacity is greater than or, in some cases, equal to the needs of the largest machine-building plants.

From the point of view of technological specialization, forging plants can be classified as follows:

• plants for the production of stamped forgings of small and large weights, a wide range of weights (universal by weight);
• factories for the production of forgings from ingots, rolled products, ingots and rolled products;
• factories for the production of stamped and forged forgings.

A forging plant can have a high level of specialization even if it is generally a universal enterprise, but the forging shops that are part of it are highly specialized in equipment, technological processes, weights and range of products.

For example, a large center body may include the following workshops: stamping hammers for the production of large forgings; hot-forging crank presses for the production of medium-weight forgings; forging machines and small presses; automatic production lines. Such a forging plant is universal in terms of a wide range and weight of stamped forgings, however, each of its workshops is specialized in a certain type of technological process, a certain weight of forgings, or the production of forgings of a narrow range of standard sizes (automatic line workshop).

According to the range of products produced, forging plants can be sectoral or inter-industry. Industry forges produce products for the needs of one industry (for example, automobile or aviation) or one large industrial complex of one industry (for example, a large complex of factories for the production of heavy-duty trucks).

Interindustry forging plants produce products for the needs of several industries, either on a territorial basis or based on the homogeneity of the range of forgings (for example, a center body for heavy forgings or a die cube plant for several industries). Factories created on a territorial basis produce products for the needs of one economic region or several nearby economic regions. An interindustry center body can be designed to supply forgings to factories of one large industrial hub or an industrialized city (several cities).

Independent forging plants have a higher level of specialization than complex procurement plants. The more different types of procurement production are concentrated in one centralized plant, the lower the level of its technological specialization.

Pressure processing produces workpieces using forging, stamping and special processes.

Before forging and stamping, the source metal (ingots, rods, etc.) is prepared for processing: the metal is stripped, cut into pieces, and the temperature regime and type of heating device are selected.

Table 1. Tolerances for the length of workpieces (dimensions, mm)

Cleaning the metal from surface defects prevents the appearance of defects in parts. Various cleaning methods are used: fire with and without heating, with a pneumatic hammer, on a milling machine, with abrasive

in circles. Cleaning with abrasive wheels is 2...3 times more expensive than sanding with a pneumatic hammer, and the cost of fire sanding without preheating is 30...40% lower than the cost of sanding with a pneumatic hammer and is approximately the same as the cost of sanding with a pneumatic hammer with preheating.

Cutting metal into pieces is carried out using saws and scissors, gas-flame, electric spark and anode-mechanical methods. In table 1 shows the tolerances for the length of workpieces when cutting.

Forging produces simple-shaped forgings weighing up to 250 tons with large overlaps. Using a special tool, they reduce the overlap. Allowances and tolerances for forgings produced on hammers are from 5 -2 + 1 to 34 ± 10 mm, and for forgings produced on presses from 10 ± 3 to 80 ± 30 mm; for untreated areas, maximum deviations are reduced by 25...50%. Using backing dies (closed and open), forgings weighing up to 150 kg (mainly small ones up to 5 kg) with a relatively complex shape without overlaps are obtained: allowances - from 3 mm and above, tolerances -1 + 1.5 mm.

The power of a forging plant (of a certain type), ensuring the achievement of the highest production indicators, the practical improvement of which cannot be achieved by further increasing power, is optimal, the value of which depends primarily on the serial production and the average weight of forgings (Table 2).

Table 2. Capacity of forging plants for the production of stamped forgings

A serious factor limiting the power of center bodies is the radius of production connections, i.e., the distance to consumer plants. Practical and calculated data show that the optimal distance for transporting forgings is up to 1000 km. Transportation over long distances leads to a decrease in the efficiency of the forge plant.

The forging shops that are part of the center body must have a capacity higher than optimal (Tables 3 and 4).

Table 3. Production divisions of forging production

Table 4. Recommended capacities of forging and pressing shops

* - when working in three shifts.

** — maximum weight of the ingot, kg.

Equipment for open-die forging workshops

Information on general purpose forging and stamping equipment is given in Table. 5. The choice of specific equipment depends on the complexity of the forgings planned for production.

Table 5. General purpose forging and stamping equipment

The complexity of forgings is determined according to the classification scheme (Fig. 1). The simplest are forgings of constant cross-section, obtained by broaching with simultaneous turning at 90° or without turning (group I). This group includes all smooth shafts and forged blanks of rectangular cross-section. Forgings produced by upsetting or broaching of variable cross-section are classified in group II: flat disks, stepped shafts with one or two shoulders.

More complex are forgings with a stitched hole (rings, gears), in the form of all-round forged cubes (stamped and other cubes, rectangular plates), as well as forgings of levers with heads and curved ones of simple constant cross-section. These forgings belong to group III.

Forgings produced by piercing followed by drawing on a mandrel, multi-stage shafts, plates with protrusions, bent brackets are included in group IV.

Obtained by piercing followed by rolling out rings, rollers or rods with flanges of large diameter and low height, levers and rods with two heads or bosses are classified in group V.

Forgings that combine in various combinations elements of forgings of the first five groups, requiring special forming tools and special devices for their production, are included in groups VI-IX. These are, as a rule, complex variable-section levers with bosses of different shapes, crankshafts, stepped rings, variable-section brackets, cargo hooks, etc.

Press forgings are divided into five groups. In terms of configurations and manufacturing complexity, press forgings of groups I and II correspond to hammer forgings of groups I and II; press forgings of group III - hammer forgings of groups III-IV; press forgings of group IV - hammer forgings of groups V-VI; press forgings of group V - hammer forgings of groups VII, VIII and partly group IX.

For the production of low-weight forgings from rolled blanks, pneumatic forging hammers are used (Table 6), and for the production of medium-weight forgings, double-action steam-air forging hammers are used (Table 7). Hydraulic forging presses are used to produce medium and large forgings from rolled billets and ingots.

Rice. 1 . Complexity groups of forged forgings

Based on the type of frame, there are single-column and four-column presses. In some cases, special two-column presses can be used. Single-column presses (table) are manufactured with a force of 1961...11768 kN and are used primarily for the production of forgings by the broaching method.

Four-column hydraulic forging presses (Table 9) are used for the production of large forgings from ingots. Presses of this type are manufactured with a force of 7845...147100 kN.

Table 6. Pneumatic forging hammers

Table 7. Double-action forging hammers*

* For all hammers, the distance from the bottom striker mirror to the floor level is 750 mm; air pressure before intake is 0.5…0.7 MPa.

Table 8. Hydraulic single-column forging presses

* Data is indicative.

Table 9. Hydraulic four-column forging presses