JPH0270347A - Manufacture of forging member - Google Patents

Abstract

PURPOSE:To prevent the generation of a forging crack by constituting the title member so that a fitting projecting part of one stock does hot protrude to the outside in the thickness direction from a fitting recessed part of the other stock, and welding and joining them to each other in a state that the recessed and the projecting parts are fitted to each other. CONSTITUTION:First of all, with regard to plate thickness, the plate thickness of each member is set relatively so that the thickness dimension of a first stock 2 becomes large than thickness of a second stock 3. Also, a coupling structure of both of them is formed as a recessed and projecting parts fitting structure, and a fitting projecting part 31 constituted of an end part 3a of a second stock 3 is fitted into a fitting recessed part 21 form on a first stock side 2. Subsequently, a first stock 2 and a second stock 3 are combined with a prescribed step difference in the plate thickness direction so that both upper and also faces 3a, 3d of a second stock 3 are positioned between both upper and lower faces 2a, 2b of a first stock 2. In such a state, joint parts of both of them are welded and joined by TIG welding, by which a roughly battledore-like forging stock 1 is obtained. Accordingly, even if a defect caused by welding is generated in a weld zone 14, it does not develop to a forging crack, and the generation of the forging crack can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a forged member.

(Prior art) Conventionally, when forging automobile parts, etc., it has been common to first form a round bar-shaped forging material by extrusion molding or the like, and then press-forming this forging material in the forging process. (See, for example, Japanese Patent Application Laid-Open No. 59-206133).

However, according to such conventional manufacturing methods of forged parts, the forging material is in the shape of a round bar, so when obtaining a forged product with a complex shape with large changes in wall thickness or shape, for example, the forging material is There was a problem that the yield was poor.

Against this background, in recent years, welding multiple materials to produce forging materials with shapes similar to those of forged products.
Attempts have been made to forge this to obtain a forged member of a predetermined shape.

(Problem to be Solved by the Invention) However, when forging a forging material obtained by welding a plurality of materials in this way, defects due to welding, For example, due to the occurrence of microshrinkage and the coarsening of crystallized substances and crystal grains, its deformability is lower than that of the base metal, and therefore, there is a risk that cracks may occur if tensile stress is applied to this welded part in the early stage of forging. was there.

The occurrence of such forging cracks is more noticeable when the plurality of materials constituting the forging material are made of different materials.

Therefore, the present invention aims to prevent forging cracks in the welded joints of the forging materials in a method for manufacturing a forged member in which a forged member of a predetermined shape is obtained by forging a forging material formed by welding and joining a plurality of pieces of wood. This was done with the aim of making it possible to perform molding without causing any generation of cracks, and to ensure that the strength of the joint is comparable to that of the base material.

(Means for Solving the Problems) In the present invention, as a means for solving such problems, a forging material formed by welding and joining a plurality of materials to each other is formed into a predetermined shape in a forging process. , approximately U extending over the entire length in the thickness direction of one of the pair of materials to be joined to each other among the plurality of materials.
A fitting recess of the shape and a fitting protrusion capable of fitting into the fitting recess of one of the wood pieces are formed on the other material, and the thickness of the one material near the fitting recess is set as above. The thickness of the other material is set to be larger than the thickness near the fitting protrusion of the other material, and the thickness of the one material and the other material is set so that at least the fitting protrusion of the other material is larger than the fitting concave part of the one wood. The above-mentioned forging material is manufactured by welding and joining each other in a state in which the projections and recesses are fitted so as not to protrude outward in the thickness direction, and then the above-mentioned forging material is put into the above-mentioned form in a semi-closed forging die. It is characterized by forging each material into a predetermined shape by applying pressure in the thickness direction of each material.

(Function) In the present invention, by having such a configuration, (1)
In the initial stage of forging, only one of the materials having a larger dimension in the pressing direction is deformed under pressure, and due to the deformation force, the material is positioned between the fitting recess and both sides of the one material. (2) Compressive stress acts on the weld between the fitting protrusion of the other material. (2) As the pressure deformation progresses, the other wood also deforms, and these materials are shaped into the forging die. In the latter stage of forging, when the concave part is filled and a part of it flows out from the mating part of the forging die as paris, a larger compressive stress acts on the welded part due to the outflow resistance of the paris, and the welding part is damaged. The area receives the training effect due to retrograde flow, and other effects can be obtained.

(Effects of the Invention) Therefore, according to the method for manufacturing a forged member of the present invention, when a forging material made by welding and joining a plurality of materials is forged using a forging die, the welded part is formed from the beginning of the forging process. Since compressive stress continues to act until the later stage and the weld is constantly subjected to compressive deformation, (1) In the early stage of forging, even if there is a defect in the weld due to welding, this will develop into forging cracking. (2) As forging progresses, the forging effect of retrograde flow on the weld gradually increases, and microshrinkage disappears or crystallization occurs in the weld. The structure is improved by making the particles and crystal grains finer, and the strength performance is improved.

(Example) Hereinafter, the method for manufacturing a forged member of the present invention will be described by taking as an example a case where a connecting rod for an engine is forged.

Figure 1 shows the forging material l used for forming connecting rods.
It is shown. This forging material 1 includes a substantially rectangular plate-shaped first material 2 which becomes a forming part of the large end of the connecting rod (corresponding to one of the materials in the claims), and a forming part of the trunk and small end. The second material 3 (corresponding to the other material in the claims) is integrally welded and joined, and the first material 2 and the second material 3 each meet their required performance. The material is set accordingly. That is, the first
Since the material 2 corresponds to the large end, which requires low thermal expansion in order to ensure fitability with the crankshaft, in this example, the first material 2 is made of a material with low thermal expansion. Aluminum alloy (JISA4032,
Composition: Aσ-12Si-1,0cu-1,0Mg 1
．． 0Ni) is adopted. On the other hand, the second material 3
Since this corresponds to the trunk and small end portions which have severe loading conditions and particularly require high-temperature strength, in this example, the second material 3 is made of an aluminum alloy (JISA2NO+, composition: A ( 1-2,0Cu-
1,5Mg-1°OFe-1,ON i) is adopted.

In this embodiment, the first material 2 and the second material 3
The present invention is applied to forming a forging material 1 by welding and joining. That is, first of all, regarding the plate thickness, the first element + 42
The plate thickness of each part (O) is set relatively so that the thickness of A U-shaped fitting recess 21 having a fitting structure and formed on the first cable material 2 side
A fitting convex portion 31 constituted by the end portion 3a of the second material 3 is fitted inside.

Then, the first material 2 and the second material 3 are combined so that the upper and lower surfaces 3c and 3d of the second material 3 are the upper and lower surfaces 2a of the first material 2.
, 2B with a predetermined step in the plate thickness direction, and in this state, the joint of the two is 'r
The materials are welded and joined by IG welding, thereby obtaining a substantially battledore-shaped forging material 1. In addition, Figure 5 (100 times enlarged) and Figure 6
The figure (enlarged 50 times) shows the first composite material 2 of this forging rope material l.
3 shows a photograph of the structure of the welded portion between the first piece of wood and the second piece of wood 3. According to these microstructure photographs, it can be clearly seen that the structure of the welded part is dotted with microtubular linkages and that crystallized substances or crystal grains are coarsened.

Next, the forging material 1 formed in this manner is then used in a semi-closed forging die 10 (see FIGS. 2 to 4), which will be described later.
Hot forged. Forging mold! 0, as shown in FIGS. 2 to 4, an upper mold 11 having a molding surface 11a formed on its lower surface and a lower mold 12 having a molding surface 12a formed on its upper surface.
The molding surfaces 11a of the upper mold 11 and the lower mold 12,
A molded recess 13 is formed between the portions 12a.

Incidentally, FIGS. 2 to 4 show a portion of this forging die IO corresponding to the AA cross section in FIG. 1.

To explain the forging process using this forging die lO according to the progress of the work, first, as shown in FIG. The molding surface 61 of the upper mold 11 is brought into contact with the side. In this state, the first material 2 of the forging materials l
Only the forging die 10 is in contact with the forming surfaces 11a and 12a,
The second cable material 3 is not in contact with these.

When forging is started by applying pressure between the upper die 11 and the lower die 12 from the state shown in FIG. The second X material 3 fitted into the fitting recess 21 starts to flow, and compressive force is applied from both sides thereof, causing the welded portion 14 to undergo compressive deformation. Therefore, even if the structure of this welded portion 14 has defects caused by welding as described above, this will not lead to forging cracks in this welded portion 14.

Further, as the forging progresses, the forming recess 1 of the forging die 10
3 is filled with the first material 2 and second material 3, the fourth material is filled with the first material 2 and the second material 3.
As shown in the figure, the excess thickness of the forging rope material l is inserted into the forging die lO.
When the welding part 14 starts to flow as it is squeezed from the mating part and flows as a lateral part, the flow resistance of this part acts as a compressive force on the welded part 14, and since the welded part 14 does not receive even greater compressive stress, It is deformed and molded into a predetermined shape.

Due to compression deformation in the latter half of this forging process, the forging material 1
The welded portion 14 is sufficiently trained and its structure is improved. In addition, Figure 7 (100x magnification) and Figure 8 (50x magnification)
(double enlargement) shows the forging material l after the forging process is completed.
As can be seen from this microstructure photo, due to the forging effect during forging, defects such as micron urinary defects disappear due to retrograde deformation of the weld 14, and The product is fragmented and refined, and the crystal grains are deformed into fibers. By improving the structure of the welded portion 14 in this way, the strength performance of the welded portion 14 is improved to a degree that is almost close to that of the base metal.

As described above, according to the manufacturing method of the present invention, each material 11.
It is possible to obtain a forged member (connecting rod) with high strength performance of the welded part 14 without causing forging cracks in the welded part 14 of 12, and especially for forged parts made of a combination of different materials as in this example. This method is effective as a method for manufacturing a forged member using the material 1.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a forging material used for carrying out the manufacturing method of the present invention, FIGS. 2 to 4 are explanatory diagrams of the state of forging using this forging material, and FIGS. 5 to 8 The figure is a photograph of the metallographic structure of the weld.・Forging material ・First material ・Second material ・Forging mold ・Upper die ・Lower die ・Forming recess ・Welding part ・Fitting concave part ・Fitting convex part h″ groan °＼(,1 1tonn Fig. 5 Fig. 6 Fig. 4 ■ Fig. 8

Claims (1)

[Claims] 1. A method for manufacturing a forged member, in which a forging material formed by welding and joining a plurality of materials to each other is formed into a predetermined shape in a forging process, wherein a pair of materials to be joined to each other among the plurality of materials. One of the materials has an approximately ■-shaped fitting recess extending over its entire length in the thickness direction, and the other material has a fitting protrusion that can fit into the fitting recess of one of the materials. At the same time, the thickness of the one material near the fitting recess is set to be larger than the thickness near the fitting convex of the other material, and the one material and the other material are at least The forging material is welded to each other in a state where the fitting convex portion of the other material does not protrude outward in the thickness direction from the fitting concave portion of the one material, and the fitting convex portion is fitted with the concave portion and the concave portion of the other material. 1. A method for producing a forged member, which comprises: manufacturing the forging material, and then forging the material into a predetermined shape by applying pressure in the thickness direction of each of the materials in a semi-closed forging die.