RU2369459C2 - Method of production of flat forged pieces by forging - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: ring produced by forging is split along generatrix. The split ring is unwound. For this purpose a gap is left between the ends of the ring in the place of split when rectifying sections of the split ring. Further produced split is increased with wedge expansion of the split ring; the ring is unbent. Wedge expansion is performed at one or several wedge strikers with different width and/or different angle at the top. Number of rectified sections of the split ring and value of their length are chosen from condition of facilitating sliding of edges of the split ring along side surfaces of wedge strikers. Further the unwound ring is rectified.

EFFECT: reduced labour intensiveness of forging, and possibility to fabricate forged pieces at standard equipment utilising standard forging gear.

4 cl, 8 dwg, 1 ex

Description

The invention relates to forging production and can be used for the manufacture of large flat forgings such as plates, discs for critical products.

A known method of forging flat forgings, including billeting of the ingot and its broaching (AS USSR No. 1489911). The disadvantage of this forging method is that in the finished forging there remains a metal of the axial zone of the ingot, which is most contaminated with non-metallic inclusions and impurities. This reduces the quality of forgings and the ability to use them for the manufacture of critical products.

A known method of forging flat forgings, including ingot upsetting, piercing, forging on a mandrel, obtaining intermediate forgings - rings, cutting this ring along the generatrix, its unfolding and dressing to the shape of a plate (USSR AS No. 852429).

The disadvantage of this method is that the deployment operation is low-tech, time-consuming to perform and requires special additional equipment.

The objective of the invention is to reduce the complexity of the forging process, making it possible to manufacture forgings on standard forging equipment using conventional forging equipment.

The problem is solved due to the fact that in the proposed method, which includes forging the ring, cutting it along the generatrix, expanding and straightening, unrolling, is carried out by straightening individual sections of the ring, followed by wedge distribution and unbending.

The straightening of sections of the cut ring is carried out on a mandrel with a flat or concave working surface.

Wedge distribution is carried out on one or more wedge-shaped strikers of different widths and / or with different angles at the apex.

The number and length of the rectifiable sections are chosen so that the gap formed during straightening would ensure that the edges of the cut ring slip along the lateral surfaces of the wedge strikers. In particular, during the straightening of two sections of the ring adjacent to the cut, their length is chosen so that the non-rectifiable part of the forging is an annular sector based on a central angle, the value of which would not exceed the value 2 (π-α-φ), where 2α - angle at the top of the wedge, φ is the angle of friction.

The bending of the workpiece is carried out on the plate in its entirety or on a step striker with flat work surfaces in sections by alternating compression and feeds.

The invention is illustrated by drawings:

figure 1 - the operation of rolling the ring on the mandrel, where 1 is the forging ring, 2 is the mandrel, 3 is the rolling striker;

figure 2 - scheme of cutting the ring along the generatrix after rolling;

figure 3 - diagram of the straightening of the extreme sections of the ring adjacent to the cut, where 4 is a mandrel with flat working surfaces;

figure 4 - operation of the distribution of the workpiece on the wedge strikers, where 5 - wedge strikers;

figure 5 - the operation of unloading and straightening on the plate, where 6 is the plate, and 7 is the finished forging;

6 is a design diagram for determining slippage conditions;

7 is a diagram of the straightening of the extreme sections of the ring on a mandrel with a concave working surface, where 8 is a mandrel with a concave working surface;

Fig. 8 is a diagram of the unbending of a workpiece on a step striker with flat work surfaces, where 9 is a step striker.

The method is implemented as follows. The ingot is bottled, precipitated and stitched. Then rolled out on a mandrel to such a size so that after deployment, the workpiece was close to the forging dimensions of the product (figure 1). Next, the ring is cut along the generatrix (figure 2). Then straighten individual sections, in particular the edges of the cut ring (figure 3). The straightening is carried out by radial compression on a mandrel having a flat working surface. In this case, a gap is formed between the cut edges. Next, increase this gap by wedge distribution (figure 4). Wedge distribution is carried out on one or several strikers of different widths and / or with different angles at the vertices to a value that ensures subsequent bending of the workpiece on the plate. The last operation is the unloading and editing of forgings on the plate (figure 5)

The straightening of individual sections after cutting the ring is carried out so that upon subsequent distribution by wedge strikers, the edges of the workpiece slide along the inclined surfaces of the wedge strikers. Otherwise, in the absence of sliding, there will be unacceptable curvature and deformation of the workpiece.

In particular, during the straightening of sections of the cut ring adjacent to the place of cutting, sliding is guaranteed to take place if the angle between each straightened section of the ring and the normal to the side surface of the wedge striker is greater than the angle of friction of the forging against the strikers. For this, it is necessary to straighten the sections of such a magnitude that the remaining non-rectified part of the workpiece is an annular sector based on a central angle, the value of which does not exceed the value

,

,

where 2α is the angle at the top of the wedge, φ is the angle of friction (Fig.6).

Figure 6 shows the design scheme for determining the slippage condition. The angle ψ between the rectified portion of the ring and the normal n to the inclined surface of the wedge is equal to ψ = π / 2-α-β

For slippage it must be greater than the angle of friction, i.e. ψ≥φ or π / 2α-β≥φ.

Because β = (γ-π) / 2, then π / 2-α- (γ-π) / 2≥φ. Then γ≤2 (π-α-φ).

To increase the clearance during straightening, this operation can be performed on a mandrel 8 having a concave working surface (Fig. 7).

In the case of insufficient gap between the ends and the impossibility of carrying out the unbending operation entirely on the plate (Fig. 5), this operation can be carried out in sections on a step gantry 9 with flat working surfaces by alternating compression and feeds (Fig. 8).

Example. The method was implemented on a press with a force of 120 MN for forging a workpiece intended for the manufacture of the bottom of an atomic reactor. An ingot weighing 159.7 tons from 15Kh2NMFA steel heated to forging temperature was shot, a block with a diameter of 1940 mm and a height of 5200 mm was cut down. Then the block was besieged by 60% in height and stitched with a stitching diameter of 900 mm. This billet was rolled out and extended on a mandrel, having received an intermediate forging in the form of a ring with a length of 3500 mm, an outer diameter of 2750 mm and an inner diameter of 1550 mm.

Next, the resulting ring was cut along the generatrix by fire cutting.

Then, two sections of the ring adjacent to the cut were rectified on a mandrel with a concave working surface. The resulting gap between the edges of the cut was 800 mm.

Distribution of the workpiece was carried out on two wedge strikers with angles at the apex of 110 ° and 130 °. After the distribution on the first wedge, the clearance was 2200 mm, and after the distribution on the second, 3100 mm. Further unloading was carried out on a stepped lower striker, and the final straightening was performed on a flat plate. As a result, after forging of side waste, a forging with dimensions of 5300 × 3500 × 600 mm was obtained.

The proposed method of forging can improve the quality of metal and the reliability of critical products. It is possible to use this method for various metals and alloys, including difficult to deform. To implement the proposed method does not require the use of additional special equipment - it is implemented on standard forging presses using conventional forging equipment.

Claims (4)

1. A method of manufacturing flat forgings by forging, including obtaining a forging ring, cutting along the generatrix, expanding the cut ring and dressing, characterized in that the deployment of the cut ring is carried out by forming a gap between its edges at the cut site, which is made by straightening sections of the cut ring, subsequent increasing the said gap by the wedge distribution of the cut ring and its extension, while the wedge distribution is performed on one or more wedge strikers having different width and / or a different angle at the vertex, and the number of rectifiable portions cut ring size and their length are selected from the slip condition to ensure the cut edges of the ring on the side surfaces of the strikers of wedge. 2. The method according to claim 1, characterized in that the straightening of sections of the cut ring is carried out on a mandrel with a flat or concave working surface. 3. The method according to claim 1, characterized in that the unloading is carried out in sections on a step gantry with flat working surfaces by alternating compression and feeds. 4. The method according to claim 1, characterized in that the rectification of sections of the cut ring adjacent to the place of the cut, with the receipt of the non-straightened part of the cut ring in the form of an annular sector with a central angle, the value of which does not exceed 2 (π-α-φ), where 2α is the angle at the top of the wedge and φ is the angle of friction.

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