JP2514400B2 - Closure forging method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a closed forging method, and more particularly, to a long machine part manufactured by closed forging, which has a specific shape at both ends thereof. In the case of doing, first, while pressing the rod-shaped material with a movable split die in a direction orthogonal to its axis, push the punch into the split die to swell both ends of the material, and in the next step By stretching the material in the axial direction with a punch and performing finish molding on it,
The present invention relates to a closed forging method capable of performing well-balanced processing in consideration of volume distribution, and particularly suitable for forging thin products.

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 part 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 of 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, the number of steps is large, the productivity is not improved, and the yield rate is poor because burrs are generated, and moreover, there are marks left after removing the burrs on the product in the trimming step for punching the burrs. Occurs, and high processing accuracy cannot be maintained.

Therefore, in recent years, various processes by closed forging have been proposed. Technical ideas relating to this closed forging include, for example, JP-A-60-49824, JP-A-60-247432, JP-A-60-102246, and JP-A-60-28937. Bulletin,
JP-A-60-42426, JP-A-60-115650, JP-A-62-137135, JP-A-56-128636, JP-A-56-128637, etc. Has been disclosed in.

With this type of closed forging technology, the material is sandwiched between split dies,
The punch is inserted from the outside into the material closed in the split mold to thereby plastically deform the material, thereby forging the material into a predetermined shape. According to such closed forging, burrs are hardly generated at the time of molding, and the number of working steps can be reduced (Japanese Patent Laid-Open Nos. 56-128636 and 56-128636). 56-128637 and JP-A-60-49824).

When forming the connecting rod by such closed forging,
A rod-shaped material is installed between a pair of split dies, and a punch is pushed into the split dies from the outside to extrude the material to form a connecting rod portion of the connecting rod, and then as described above. By performing upsetting using a punch on the end of the primary processed product formed by forming, the large end and the small end of the connecting rod are formed. In this case, two forming processes of extrusion and upsetting are required, and once the connecting rod portion of the connecting rod is formed by extrusion, then both ends are crushed and expanded by upsetting. , The flesh flow in the material is different for each part. As a result, a part with a large processing rate is generated in part, and the material is overloaded. As a result, cracks often occur, causing defective products.

Further, in recent years, when the connecting rod portion of the connecting rod is processed into a thin H-shape in order to promote the weight reduction of the internal combustion engine, there is an extreme difference in volume distribution between the connecting rod portion and the large end portion or the small end portion. Therefore, there is a drawback that it is difficult to form the connecting rod portion.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned inconvenience, and in processing a machine part having a long shape and swelling at both ends by closed forging, a plurality of materials are used. While pressing with a split die in the direction orthogonal to the axial direction, the material is bulged by crushing the ends by the cooperation of upper and lower punches along the axial direction, and then pressed with the split die. Closed forging suitable for forming thin and lightweight machine parts without pushing the material forcibly, which makes it possible to obtain the final product by final forming by closing forging by performing extrusion with a punch. The purpose is to provide a method.

[Means for Achieving the Purpose] In order to achieve the above-mentioned object, the present invention is a closure for forming a material into a desired shape by inserting a punch from the outside while a rod-shaped material is sandwiched by a plurality of split dies. A forging method, in which the split die is pressed against the material from a direction orthogonal to its axial direction to squeeze the material and the material is pressed axially against the material under the cooperation of a pair of punches. A first step of performing upsetting to swell both ends, and a material that has been subjected to the first step is pushed by a split die from a direction orthogonal to the axial direction of the raw material, and a punch is inserted into the split die to make the raw material. A second step of performing an extrusion process in which the material is pressed from one end side to stretch the material in the axial direction thereof;
It is characterized in that it comprises a third step of finish forging the raw material which has undergone the steps into a final shape by using a finish forming die.

Further, according to the present invention, the raw material is formed into a rough-formed primary molded product in the cross-sectional direction in the first step, and then the large end portion, the small end portion and the cross section I which are substantially formed into the final shape of the connecting rod in the second step.
It is characterized in that a rough-molded secondary molded product having a V-shaped connecting rod portion is obtained, and finally a connecting rod having an H-shaped cross section of the connecting rod portion is obtained in the third step.

[Embodiment] Next, a preferred embodiment of the closed forging method according to the present invention will be given and described in detail below with reference to the accompanying drawings.

FIG. 1 shows a closed forging device used in the closed forging method according to the present invention to rough-form a raw material. That is, the closed forging device 10 is basically composed of an upper mold 12 that can be raised and lowered and a fixed lower mold 14.

First, the upper die 12 includes a piston 16 connected to a hydraulic cushion, and an upper die 18 provided at the tip of the piston 16.
And the upper mold body 19 and the holder 20 independently of the piston 16.
The upper die punch 22 is mounted through the upper die punch 22. The upper die punch 22 is configured to be inserted into a hole 24 formed in the central portion of the upper die 18 and to have its tip end projected. The upper die punch
The shape of the tip end of 22 is determined according to the shape of the rough-formed product, and in this case, a trapezoidal protrusion is formed.

Next, the lower mold 14 includes a lower mold base 26, a lower mold die 28 mounted on the lower mold base 26, and a plurality of cushion means 30 installed in the lower mold die 28. First, 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 arranged below the hole portion 32, and a lower die punch 36 is attached to and detached from the holder 34. It is installed freely. 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 is composed of four divided dies 38a to 38d and a die case 40 in which the divided dies 38a to 38d are installed and which are displaced in a direction to bring them close to each other. The back of the housing is regulated by the housing 42, and the coil spring 43 of the cushion means 30 is always elastically biased upward.

Therefore, as shown in FIG.
A molding portion 44 corresponding to the shape of the workpiece is defined by the four surfaces of 8d which face each other. In this case, the molding portion 44 is formed in a shape corresponding to the primary molding product of the rough-rod molding product of the connecting rod. In contrast, the split dies 38a to 3
Sloping surfaces 46a to 46d each having a diameter increasing downward are formed on the rear rear surface portion of 8d. On the other hand, the inclined surfaces 46a to 46d
Inside the die case 40 which slides along the same, inclined surfaces 48a to 48d which similarly expand in the downward direction are respectively provided in the split dies 38a.
To 38d are formed. Then, the respective split dies 38a to 38d are formed with guide portions 49a to 49d projecting to both sides thereof along the inclined surfaces 46a to 46d, and the guide portions 49a to 49d are slid to correspond thereto. Guide grooves 50a to 50d, which are movably fitted, are respectively formed on the inclined surface of the die case 40.
It is defined on both sides of 48a to 48d. As can be understood from FIG. 1, 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 descends while being guided by guide portions 49a to 49d formed on the split dies 38a to 38d while the rear surface of the die case 40 is restricted by the housing 42, and the inclined surfaces 48a to 48d inside the die case 40 are divided into the split dies 38a to 38d. 38d slides along the inclined surfaces 46a to 46d at the rear part of the back. as a result,
The respective split dies 38a to 38d are horizontally displaced close to each other, so that the distance between the molding portions 44 defined inside the split dies 38a to 38d is reduced. is there.

By the way, the upper die punch 22 shown in FIG. 1 and FIG.
The split dies 38a to 38d are used for forging a primary molded product among rough-rod forged products of connecting rods, and when the secondary molded product is forged in the next step, the upper die punch 22 is used. , The upper die punch 51 and the dividing dies 52a to 52d shown in FIG. 3 are used instead of the dividing dies 38a to 38d. The tip of the upper die punch 51 is formed in a shape corresponding to the secondary molded product of the connecting rod, and in this case, a semicircular projection 54 is formed. In addition, a molding portion 56 of the secondary molding product is defined by the facing surfaces of the split dies 52a to 52d. In this case, among the split dies 52a to 52d, long ridges 58 are formed on the split dies 52b and 52d for processing the rod portion of the secondary molded product into an I-shaped cross section. Also, the split dies 52a, 5
Protrusions 59 are formed on 2c, respectively. Except for the above configuration changes, the dividing dies 52a to 52d and the dividing dies 38a to 38d are configured in the same manner.

The closed forging device according to the present embodiment is basically configured as described above. Next, the case where the connecting rod is forged using the closed forging device is given as an example, and the closed forging method is used. Will be described below.

FIG. 4 is a diagram showing the shape of a molded product for each step in the closed forging method according to the present invention.

In the figure, reference numeral 60 indicates a round bar-shaped billet as a raw material, and reference numeral 62 indicates a primary molded product of a connecting rod processed by rough forging. This primary molded product 62
Is a relatively small bulge 64 formed on one end side thereof,
Large bulging portion 66 that bulges while deviating from the axial direction at the other end side
The rod portion 68 connecting the small bulge portion 64 and the large bulge portion 66 is formed in a rectangular shape in cross section and is relatively short, and the rod portion 68 is formed on both sides of the large bulge portion 66. An undercut portion 70 that curves toward the rod portion 68 is formed. Then, the primary molded product 62 is processed into a secondary molded product 72 shown in the figure in the next step. In the secondary molded product 72, the small bulging portion 64, the large bulging portion 66, and the rod portion 68 of the primary molded product 62.
Is formed with a small end portion 74, a large end portion 76, and a connecting rod portion 78 having a shape approximately similar to each corresponding portion of the connecting rod, and the connecting rod portion 78 has an I-shaped cross-section (fifth portion). See figure). Further, the secondary molded product 72 is processed into a connecting rod 80 as a product through a finishing process. In this case, the connecting rod
The cross-sectional shape of the connecting rod portion 82 of 80 is processed into a thin H-shape (see FIG. 6).

Therefore, as shown in FIG. 1, the billet 60 heated to a high temperature is installed in the molding section 44 between the split dies 38a to 38d so that one end of the billet 60 contacts the tip of the lower die punch 36. Next, the upper die 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 die 18 of the tip of the piston 16 to push the coil spring 43 elastically. Displace downward against the force. The die case 40 is displaced along the inclined surfaces 46a to 46d of the split dies 38a to 38d by the pressing action of the upper die 18, and at this time, the die case
Since the rear surface of 40 is abutted against the housing 42 and regulated, and only vertical displacement is allowed, the split dies 38a to 38d are displaced toward each other in the horizontal direction as the die case 40 moves downward. Will be received.

As shown in FIGS. 7a to 7c, the split dies 38a to 38d are displaced toward each other in the direction of being close to each other, and the molding portion therebetween is formed.
At 44, the billet 60 is pressed and squeezed by the dividing dies 38a to 38d in the direction orthogonal to the axial direction thereof (see FIG. 7a). When the die case 40 is further lowered, the lower end of the billet 60, which is pressed by the split dies 38a to 38d, is restricted by the lower die punch 36, so that the billet 60 is extended upward and bulges. At approximately the same time, the upper die punch 22 disposed via the upper die body 19 and the holder 20 enters the molding portion 44 between the split dies 38a to 38d, and moves in the axial direction with respect to the billet 60. Start upsetting (see FIG. 7b). Further, when this state is continued, the billet 60 is pressed by the cooperation of the upper die punch 22 and the lower die punch 36. As a result, both ends of the billet 60 are crushed to cause meat flow, and the split die 38a
The billet 60 is filled with the meat in the molding part 44 between 38d and 38d. Thus, the billet 60 is roughly forged into the shape of the primary molded product 62 shown in FIG. 4 (see FIG. 7c).

Next, the primary molding 62 is subjected to rough forging in the next step in the same procedure. In this case, in the closed forging device 10 shown in FIG. 1, the upper die punch 22 and the split dies 38a to 38d are replaced with the upper die punch 51 shown in FIG.
And split dies 52a-52d are used, while lower die punch 36 is not used.

That is, the primary molded product 62 is clamped by the facing surfaces of the split dies 52a to 52d, and the upper mold 12 is lowered. As a result, as shown in FIG. 8, the division dies 52a to 52d are displaced closer to each other under the pressing action of the die case 40, and press the side surface of the primary molded product 62. At the same time, with the lowering of the upper die 12, the upper die punch 51 enters the forming portion 56 between the divided dies 52a to 52d, and starts the pressing process for the primary formed article 62 (FIG. 8). b)).

In this case, the small bulge portion 64 of the primary molded product 62 is a free end, and therefore, the primary molded product 62 has the upper die punch 51.
When it is extruded by, in particular, the protrusion 59 formed on the split dies 52a and 52c that presses the undercut portion 70 of the primary molded product 62 and the ridge 58 formed on the split dies 52b and 52d (the mesh in FIG. 8). ), The meat of the large bulging portion 66 and the rod portion 68 of the primary molded product 62 flows downwardly. As a result, as shown in FIG. 8C, the primary molded product 62 is stretched, and in particular, the bar 68 is processed into an I-shaped cross section by the protrusion 58 formed on the split dies 52b and 52d ( (See FIG. 5). Thus, the primary molded product 62 is the fourth
It is roughly stamped and forged into the shape of the secondary molded product 72 shown in the figure.

The secondary molded product 72 is finish-forged by the double-acting die 90 shown in FIGS. 9 and 10 and processed into the final product-shaped connecting rod 80 (see FIG. 4). Where the ninth
In the figure, the double-acting mold 90 includes a lower die 92 and an upper die 94.
And a lower punch 96 and an upper punch 98 that respectively enter the lower die 92 and the upper die 94 from above and below.
Further, the double-acting die 90 is provided with the lower punch 9 as can be understood from FIG. 10 in which a sectional view taken along line XX of FIG. 9 is shown.
6. It includes a pair of side punches 100a, 100b which are displaceable in a direction orthogonal to the displacement direction of the upper punch 98.

In this case, under cooperation of the lower punch 96 and the upper punch 98, the small end portion 74 and the connecting rod portion 78 of the secondary molded product 72 are processed into the shape shown by the broken line in FIG. As a result, in particular, the connecting rod 78 has a relatively thin cross section H as shown in FIG.
It is processed into a letter shape.

According to the present embodiment, when the connecting rod 80 is forged, the rough forged product before finish forging is not forged all at once, but is divided into the process of the primary product 62 and the process of the secondary product 72. . Further, in the step of obtaining the primary molded product 62, in the step of obtaining the secondary molded product 72, respectively, the pressing by the dividing dies 38a to 38d, the dividing dies 52a to 52d and the pressing by the upper die punches 22, 51 are performed substantially at the same time, Since the plastic deformation is applied from the directions orthogonal to each other, the flesh flow progresses in a well-balanced manner, and it is not necessary to apply undue deformation. Therefore,
Since the forging is performed stepwise in harmony with the whole, the thin connecting rod for weight reduction can be forged with good processing accuracy and without cracks or the like.

[Effects of the Invention] As described above, according to the present invention, a material is sandwiched between split dies, the split dies are displaced closer to each other and pressed in a direction orthogonal to the axial direction of the material, and a vertical punch is used. To obtain a primary processed product that is preformed by pressing in the axial direction in cooperation with to form a rectangular cross section, and then extruded and stretched along the axial direction by a punch that is inserted into a split mold with respect to the primary processed product. The secondary molded product thus obtained is subjected to molding and final finish molding. For this reason, even in mechanical parts such as connecting rods, which have a thin H-shaped cross-section for weight reduction, the meat flow during processing is balanced and the material is not overloaded. As a result, the processing accuracy can be improved, the load on the mold can be reduced, and the structure of the forging device can be simplified. Therefore, it has a remarkable effect in improving the forging production efficiency as a whole and reducing the manufacturing 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 view showing the structure of a closed forging device used in the closed forging method according to the present invention, and FIG. 2 shows the structures of a split die and a die case used in the closed forging device in FIG. Partially omitted perspective view, FIG. 3 is a partially omitted perspective view illustrating the structure of a split die used when processing a secondary molded product in the closed forging method according to the present invention, and FIG. 4 is the closed forging method. Fig. 5 is a perspective view showing the shape of the processed product in each step in Fig. 5, Fig. 5 is a sectional view taken along the line VV of the secondary molded product in Fig. 4, and Fig. 6 is a sectional view taken along the line IV-IV of the connecting rod in Fig. 4. 7a to 7c are views for explaining a series of steps in rough forging the primary molded product shown in FIG. 4, and FIGS. 8a to 8c are rough stamped forging the secondary molded product shown in FIG. FIG. 9 is a diagram for explaining a series of steps in the case, and FIG. 9 is a secondary molding in FIG. Double acting die schematic sectional view of a used to forge finishing, FIG. 10 is a sectional view taken along line X-X of the double acting die in FIG. 9. 10 …… Closed 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 60 ... Billet, 62 ... Primary molded product 72 ... Secondary molded product, 80 ... Connecting rod

 ─────────────────────────────────────────────────── ───Continued from the front page (56) References JP-A-60-152338 (JP, A) JP-A-59-133928 (JP, A) JP-A-1-233035 (JP, A) Actual development Sho-63- 116134 (JP, U)

Claims (2)

(57) [Claims] 1. A closed forging method for forming a raw material into a desired shape by inserting a punch from the outside under the condition that a rod-shaped raw material is sandwiched by a plurality of split dies. A first step of pressing the material in a direction orthogonal to the direction and squeezing the material, and pressing the material in the axial direction under the cooperation of a pair of punches to swell both ends thereof. , The material that has undergone the first step is pushed by a split die from a direction orthogonal to the axial direction of the split die, and a punch is inserted into the split die to push from one end side of the raw material to stretch the raw material in the axial direction. A closed forging method comprising: a second step of performing an extrusion process; and a third step of finish forging the material that has undergone the second step into a final shape using a finish forming die. 2. The method according to claim 1, wherein the raw material is molded into a rough-pressed primary molded product having a rectangular cross section in the first step, and then in the second step, a large end portion substantially molded into the final shape of the connecting rod, Closure forging method, characterized in that a rough-pressed secondary molded product having a small end portion and a connecting rod portion having an I-shaped cross section is obtained, and finally a connecting rod having an H-shaped cross section of the connecting rod portion is obtained in a third step. .