JP2545264B2 - Closed forging method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a closed forging method and an apparatus therefor, and more specifically, in forming long machine parts having specific shapes at both ends by closed forging. The rod-shaped material is machined from a direction orthogonal to the axis by a split die that is displaced in the direction close to each other when pressed by the upper die, and both ends are expanded under the cooperation of the upper punch and the lower punch. Molding is performed to cause a balanced flow of meat with respect to the rod-shaped material, which allows forging into a rough-formed product with high processing accuracy and simplification of the structure of the forging device. TECHNICAL FIELD The present invention relates to a forging method and an apparatus thereof.

BACKGROUND OF THE INVENTION For example, in an internal combustion engine, forging using a hammer or a press machine is performed as a method of manufacturing a long mechanical component such as a connecting rod that connects a piston and a crankshaft. In this case, it is customary to go through a roughing step, a finishing step, and a trimming step for removing burrs generated in the finishing step for each of the large end portion, the small end portion, and the connecting rod portion of the connecting rod.

However, in such a method, not only the number of steps is large and the productivity is not improved, but also the burr is generated, so that the yield rate is poor, and moreover, the material which has been roughly punched in the trimming step for punching this burr is punched. The remaining marks are generated and high processing accuracy cannot be maintained.

Therefore, in recent years, various processes by closed forging have been proposed. The technical idea of this closed forging is, for example, JP-A-60-49824, JP-A-60-247432, JP-A-60-102246, and JP-A-60-28937. JP, JP 60-42426, JP 60-115650, JP 62-137135 JP, 56-128636 JP, JP 56-128637. It has been disclosed in the gazette and the like.

With this type of closed forging technology, the material is sandwiched between split dies,
The material is plastically deformed by pushing a punch from the outside into the material closed in the split mold, thereby forging the material into a predetermined shape. According to such closed forging, burrs are hardly generated at the time of forming, and the number of working steps can be reduced (Japanese Patent Laid-Open No. 56-128636, Japanese Patent Laid-Open No. 128636/1985). 56-128637 and JP-A-60-49824).

When molding the connecting rod by such closed forging,
A rod-shaped material is installed between a pair of split molds, a punch is pushed into the mold from the outside, and the material is extruded to form the connecting rod portion of the connecting rod, and then the primary rod formed as described above. The end of the processed product is subjected to upsetting using a punch to form the large end and the small end of the connecting rod. In this case, two forming processes of extrusion and upsetting are required. Once the connecting rod part is formed by extrusion, both ends are crushed and expanded by upsetting. The flesh flow in is different from part to part.

As a result, a portion with a large processing rate is generated in part, which imposes a strain on the material, which often causes cracks and causes defective products. In particular, there is a problem that a material that has been work-hardened along the axial direction by the extrusion is swelled at both ends in a crushing direction of the material, which is different from the axial direction, so that the material is easily cracked.

Further, in order to continuously perform such extrusion processing and upsetting processing, a double-acting mechanism capable of urging the split die, punch, and the like from the two directions with respect to the material is required (special feature). See Japanese Laid-Open Patent Publication No. 60-49824, Japanese Laid-Open Patent Publication No. 60-42426, and Japanese Laid-Open Publication No. 60-28937). For this reason, it is pointed out that the forging device becomes large and accordingly expensive, and the production cost accordingly rises.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned inconveniences, and a plurality of divisions are made in processing a long blanking molded product having a shape bulging at both ends by closed forging. The dies are displaced in a direction in which the diameters of the dies are reduced in accordance with the displacement of the upper mold, and the dies are pressed from a direction orthogonal to the axial direction of the material. By bulging both ends of the material, the material is plastically deformed in a well-balanced manner without undue deformation, and the desired forging process is achieved with a relatively simple structure consisting of a single-action mechanism instead of a double-action mechanism. It is an object of the present invention to provide a closed forging method and an apparatus therefor capable of performing the above.

[Means for Achieving the Object] In order to achieve the above object, the present invention forms a material into a desired shape by allowing a punch to enter from the outside while a rod-shaped material is sandwiched by a plurality of split dies. In the closed forging method, the split die is pressed against the material from a direction orthogonal to the axial direction of the material to stretch the material in the axial direction and a connecting rod portion of a conrod rough-formed product having an H-shaped cross section. In the first step of molding, the upper die punch and the lower die punch coaxially arranged at a predetermined distance are separated from each other, and one lower die punch presses one end side of the material and the other upper punch. Insert the die punch into the split die, press the material in the axial direction from the other end side for upsetting, and bulge both ends of the material to increase the size of the conrod rough-formed product. Mold ends and small ends And 2 step consists, and performs the first step substantially simultaneously with the second step.

Further, the present invention is characterized in that the connecting rod portion of the connecting rod rough-formed product is formed in the first step, and the large end and the small end of the connecting rod rough-formed product are formed in the second step.

Further, according to the present invention, a die case which is urged upward by the elastic force of the cushion means and descends under a pressing action due to the displacement of the upper die, and a molding surface of a material formed inside the die case and facing each other are formed. And a divided die having a sloping surface formed on the back of the die, in the process of sliding displacement of the die case along the sloping surface, the materials are pressed close to each other in a direction orthogonal to the displacement direction. Multiple split dies to
An upper die punch that is inserted between the molding surfaces of the split dies as the upper die descends, and a lower die punch that cooperates with the upper die punch and presses the material in its axial direction.

[Embodiment] Next, a closed forging method according to the present invention will be described in detail below with reference to preferred embodiments in relation to an apparatus for carrying out the method, with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a closed forging device according to the present invention. That is, the closed forging device 10 is basically composed of an upper die 12 and a lower die 14 which can be raised and lowered.

The upper mold 12 is a piston 16 connected to a hydraulic cushion.
And an upper die 18 arranged at the tip of this piston 16,
The upper die punch 22 includes an upper die body 19 and an upper die punch 22 mounted via a holder 20 independently of the piston 16.
22 is inserted through a hole 24 formed in the center of the upper die 18, and the tip of the hole 24 projects. The shape of the tip of the punch is determined according to the shape of the processed product, and in this case, a semicircular protrusion is formed so as to correspond to the shape of the large end of the connecting rod.

Next, the lower mold 14 is attached to the lower mold base 26 and the lower mold base 26.
And a plurality of cushion means 30 for urging the lower mold die 28 upward. A hole portion 32 extending in the vertical direction is formed in the central portion of the lower die base 26, a holder 34 is disposed below the hole portion 32, and a lower die punch 36 is provided in the holder 34. . Then, the tip of the lower die punch 36 is inserted into the lower die 28 by a predetermined length. In this case, the lower die 28 includes four divided dies 38a to 38d and the divided dies 38a to 38d, and a die case 40 for displacing the divided dies 38a to 38d in a direction to bring them close to each other. The rear surface of the housing 42 is regulated by the housing 42, and the coil spring 43 of the cushion means 30 constantly elastically urges upward.

Therefore, as shown in FIG.
Formed parts 44 corresponding to the shape of the processed product are defined by the surfaces of 8d that face each other. In this case, the molding part 44 is formed in a shape corresponding to a rough-molded product of a connecting rod, while the rear surfaces of the split dies 38a to 38d are provided with inclined surfaces 46a to 46d that expand downward. While each is formed,
On the four inner surfaces of the die case 40 that slide along the inclined surfaces 46a to 46d, the inclined surfaces 48a that similarly expand in the downward direction are formed.
To 48d are formed corresponding to the respective split dies 38a to 38d. The split dies 38a to 38d are provided with guide portions projecting laterally along the inclined surfaces 46a to 46d.
49a to 49d are formed, and correspondingly, guide grooves 50a to 50d into which the guide portions 49a to 49d are slidably fitted are defined on both sides of the inclined surfaces 48a to 48d of the die case 40, respectively. It

As can be understood from FIGS. 1 and 2, the upper die 18 of the tip of the piston 16 that integrally descends with the upper die body 19 as the upper die 12 descends presses the die case 40 downward, The die case 40 includes guide portions 49a to 4 of the split dies 38a to 38d.
While being guided by 9d, the inclined surfaces 48a to 48d are divided into the die 38a.
Through 38d slide along the slopes 46a through 46d on the back of the back. Therefore, the respective split dies 38a to 38d are horizontally displaced toward each other, so that the intervals between the molding portions 44 defined inside the split dies 38a to 38d are reduced. It is something.

The closed forging device according to the present embodiment is basically configured as described above. Next, the closed forging method will be described taking rough connecting forging of a connecting rod using the closed forging device as an example.

In FIG. 3, reference numeral 52 indicates a round bar-shaped billet as a raw material, and reference numeral 54 indicates a rough-formed product of a connecting rod formed by subjecting the billet 52 to rough-forging. The rough-formed product 54 is to be finished in the next step to be a connecting rod as a finished product. Here, the rough-formed product 54 has a continuous rod portion 56 having a long and I-shaped cross section, a small end portion 58 on one end side thereof, and a semicircular recessed portion, and is eccentric to the axial direction. And a large end portion 60 which bulges out in a position.

Therefore, as shown in FIG. 1, the billet 52 heated to a high temperature is installed in the molding part 44 between the split dies 38a to 38d so that one end of the billet 52 contacts the tip of the lower die punch 36.

Next, the upper mold 12 is displaced downward, and the upper surface of the die case 40 surrounding the split dies 38a to 38d is pressed through the upper mold die 18 at the tip of the piston 16, and the elastic force of the coil spring 43 is applied to this. Displace downward against. The die case 40 is displaced by the pressing action of the upper die 18 along the inclined surfaces 46a to 46d of the rear part of the split dies 38a to 38d, and at this time, the outer surface of the die case 40 contacts the housing 42. Since only the vertical displacement is allowed, the division dies 38a to 38d are subjected to the action of displacing each other in the horizontal direction as the die case 40 moves downward. Therefore,
The split dies 38a to 38d are displaced toward each other, and the billet 52 sandwiched between the molding portions 44 therebetween is pressed and squeezed from the direction orthogonal to the axial direction. Then, if the die case 40 is further lowered, the billet 52
Is drawn into a shape corresponding to the molding portion 44 (see FIG. 4a).

Further, substantially at the same time as this, the upper die punch 22 disposed via the upper die body 19 and the holder 20 has the above-mentioned split dies 38a to 38d.
Then, the billet 52 is inserted into the forming portion 44 inside and the axial upsetting process is performed on the billet 52. That is, while the action of a hydraulic cushion (not shown) in which the piston 16 is connected is working between the upper die body 19 and the piston 16, the upper die 18 at the tip of the piston 16 presses the split dies 38a to 38d. In the meantime, the upper mold body 19 further descends. As a result, the upper die punch
22 presses the billet 52 in the axial direction. The billet 52
Is the upper die punch 22 and the lower die punch 36 in a state in which the displacement in the axial direction is restricted by the pressing action of the lower die punch 36 on the upper side.
Upsetting is performed by the synergistic action with. Finally, when the bottom of the die case 40 comes into contact with the lower die base 26, the drawing of the billet 52 by the split dies 38a to 38d and the axial pressing by the upper die punch 22 are stopped. As a result, both ends of the billet 52 are crushed to cause meat flow, and the billet is formed in the molding portion 44 between the split dies 38a to 38d.
The meat of 52 is filled and is processed into the shape of the rough-formed product 54 shown in Fig. 3 (see Fig. 4b).

In this case, the processing applied to axially stretch the billet 52 to form the connecting rod portion 56 by the close displacement of the split dies 38a to 38d, and the small end added by the upper die punch 22 and the lower die punch 36. The upsetting process for forming the portion 58 and the large end portion 60 is performed substantially at the same time, and the meat flow proceeds in a well-balanced manner over the entire billet 52, so that there is no unreasonable deformation. Therefore, it is possible to avoid the occurrence of cracks and the like, and further reduce the load on the split dies 38a to 38d. Also, the upper die 12 provided with the upper die punch 22.
The lower dies are used to displace the split dies 38a to 38d close to each other in a direction orthogonal to the displacement direction of the upper die punch 22. Therefore, it is not particularly necessary to provide means for urging the split dies 38a to 38d, and the upside down molding by the cooperation of the upper die punch 22 and the lower die punch 36 and the lateral direction by the split dies 38a to 38d. It will be appreciated that it is possible to relatively simplify the structure of the forging device itself, since the composite forming is performed substantially at the same time as the draw forming and the action of the double acting mechanism is achieved by the single acting mechanism.

[Effects of the Invention] As described above, according to the present invention, a material is sandwiched between a plurality of divided dies, and when the upper die is displaced, these divided dies are displaced close to each other to draw and squeeze the material. In addition to performing the above-mentioned processing, in cooperation with the lower die punch and the upper die punch, upset processing is performed on both ends of the material to obtain a rough punched product having a long and bulged portion of a predetermined shape at both ends. It is configured to be possible. Therefore, stretching and upsetting can be performed all at once, the number of steps can be reduced, and unreasonable meat flow does not occur in the process of plastic deformation of the material, and therefore cracks and the like occur. And the processing accuracy can be improved. In addition, as a mechanism for displacing the split dies close to each other, a die case that houses the split dies descends along the inclined surface of the rear part of the split dies as the upper die descends, whereby the split dies are separated. Since the structure that narrows the interval of is adopted, the mechanism of the device itself is simplified,
It is possible to obtain the effect that the forging device can be manufactured at low cost. Therefore, the production efficiency of forging is raised as a whole, and a remarkable effect is obtained in reducing the production cost.

Although the present invention has been described above with reference to the preferred embodiments, the present invention is not limited to these embodiments, and various improvements and design changes can be made without departing from the scope of the present invention. Of course.

[Brief description of drawings]

FIG. 1 is a partially omitted sectional explanatory view showing a configuration of a closed forging device according to the present invention, and FIG. 2 is a partially omitted cutaway perspective view showing configurations of a split die and a die case which constitute the closed forging device according to the present invention. Fig. 3 is a perspective view showing the shapes of a billet and a rough-formed product used in manufacturing a connecting rod in the closed forging method according to the present invention, and Fig. 4 illustrates a series of steps in the closed forging method. FIG. 10 …… Closure forging device, 12 …… Upper mold 14 …… Lower mold, 16 …… Piston 18 …… Upper die, 20 …… Holder 22 …… Upper punch, 28 …… Lower die 30 …… Cushion Means, 36 ... Lower punch 38a-38d ... Dividing die, 40 ... Die case 52 ... Billet, 54 ... Rough-formed product 56 ... Continuous rod part, 58 ... Small end 60 ... Large edge

Claims (2)

(57) [Claims] 1. A closed forging method in which a rod-shaped material is sandwiched by a plurality of dividing dies and a punch is inserted from the outside to form the material into a desired shape. First, the material is stretched in the axial direction by pressing from a direction orthogonal to the axial direction and the connecting rod portion of the connecting rod rough-formed product having an H-shaped cross section is formed.
Of the upper die punch and the lower die punch which are coaxially arranged at a predetermined distance from each other in the process, one lower die punch presses one end side of the material and the other upper die punch is split die. Inside and press axially from the other end side to the material to perform upsetting, and bulge both ends of the material to swell the connecting rod to form large and small ends. A second step of forming the part, and the closed forging method, wherein the first step and the second step are performed substantially at the same time. 2. A die case which is urged upward by the elastic force of the cushion means and descends under a pressing action due to the displacement of the upper die; and a molding surface of a material formed inside the die case and facing each other. And a divided die having a sloping surface formed on the back of the die, in the process of sliding displacement of the die case along the sloping surface, the materials are pressed close to each other in a direction orthogonal to the displacement direction. A plurality of split dies, an upper die punch that enters between the molding surfaces of the divided dies as the upper die descends, a lower die punch that cooperates with the upper die punch and presses the material in its axial direction, A closed forging device comprising: