SU795691A1 - Method of producing large forgings - Google Patents

Description

(54) METHOD FOR OBTAINING A MAJOR SEARCH

one

The invention relates to the processing of metals by pressure and can be used in forging and pressing production in the manufacture of large forgings, such as plates, plates

and so on

There is a known method of forging large forgings, including the initial pre-crimping of rhombic boykits of the workpiece heated to the forging temperature along the entire length, podstuzhivanie from the surface and the subsequent stretching with flat strikers l3.

A disadvantage of the known sporob is the low quality of forgings such as plates and straight rail bars due to the absence of lateral support, which creates compressive stresses for closed internal defects in the form of cracks, voids, loose soil, etc. side of the profitable part of the ingot.

The disadvantage of this method is the limited range of forgings (narrow range of transverse settlements) due to the limited scope of application of rhombic dies with a notch angle 90 The known method does not allow

Part forgings such as plates of large width.

The purpose of the invention is to improve the quality and expand the range of forgings such as plates and rectangular bars.

The goal is achieved by the fact that in the method of obtaining large forgings, including pre-crimping of the workpiece heated to the forging temperature over the entire length, its pressing from the surface and subsequent stretching by flat strikes, and during stretching; using strikers with widths exceeding the width of the forging, first compress the middle thickened

0 part of the workpiece along its entire length, and then pull the workpiece to its final dimensions.

FIG. Figure 1 shows a scheme for pre-crimping a blanket along one of its side sections; Fig. 2 is the same on the other side section; in fig. 3 is the same, view A in FIG. 2; in fig. 4 compression of the middle part of the workpiece when

0 through.

The method is carried out as follows.

The extreme lateral portion of the pre-stretched blank 1 (see Fig. 1) is set along the longitudinal axis of the forging tool 2, 3 at a distance equal to 1/3 of its width, and crimped along the entire length with a slight displacement of the blank (in the opposite direction from the longitudinal axis of the press) with a total degree of deformation of at least 20%. After that, the workpiece (see Fig. 2) is turned over by 180 and the above operations are repeated without exception. In this way, the preform is shaped into a thickened middle part of the timber with a gradual decrease in the height of the thickening to the side portions of the preform. Then, the workpiece is installed on pads with a height of at least 10 m, located on the workshop span, and subjected to natural cooling to surface temperature, corresponding to the lower forging limit. When this occurs, intense cooling of the metal surface, as this contributes to the variable cross-section of the workpiece. In general, this creates a large temperature drop across the bottom section, especially in its central zone. During the cooling time, the workpiece is replaced with a forging tool (the longitudinal heads are replaced by conventional flat heads). Then, the middle part of the protrusions of the workpiece 1 (see Fig. 4 is crimped by flat strikers 4, 5 with their full width exceeding the width of the forging, with a reduction value of 8-10% per press stroke to obtain a rectangular section with alternate turning around 90. When crimping by flat dies, the press force is transmitted mainly to the core part of the workpiece, the temperature of which is higher compared to the outer layer of metal cooled from the surface. Such a forging scheme creates favorable conditions for welding internal defects throughout the entire volume of the workpiece. Lee preform is transmitted to the display. and then forged to the desired shape and size by conventional techniques.

The manufacture of forgings such as plates of plates and bars for powerful punching presses, for example, a force of 65,000 tons, and other products according to the proposed method will significantly increase their durability during operation.

Example. The method is carried out in the manufacture of bar forgings with a cross section of 900–1500 mm. weight of 44.0 tons of steel grade 20 HNMF. The steel is smelted in an open-hearth furnace and an ingot weighing 68.0 T is cast in a vacuum chamber. After

This ingot, in hot condition, is transferred to a press shop and put into a furnace for heating under forging. The ingot is forged under pressure with a force of 10,000 T for four blowouts.

In the first removal, the forging of a pin for the cartridge from the profitable part of the ingot and billeton to a diameter of 1510 mm was made. In the second removal, an ingot is drained to a diameter of 2400 mm and drawn to a section. In the third offset, the longitudinal side parts of the workpiece are crimped over the entire length to a height of 1250 mm using longitudinal flat dies. After this, the workpiece is pressed in air until the surface temperature is compressed by the middle part of the workpiece with flat strips covering the width of the forging to a height of 1250 mm. In the fourth offset, the final forging is performed according to the forging sketch. Forging temperature interval 1220-850 s. After the forging is completed, the forging is put into the furnace for isothermal annealing. Investigation of the quality of forgings, forged by the proposed technology, wire ultrasound testing.

In comparison with products made by a known method, the experimental forging is quite dense in terms of volume and meets the standards of ultrasonic testing.

The proposed method for forging a quiescent -vok reduces the volume of the defective zone by 2-3 times, and also significantly reduces the size of individual defects.

Claims (1)

1. USSR author's certificate 499020, cl. B 21 J 5/06, 18.08.71 Fy