JPH01237038A - Method and device for closed forging - Google Patents

Abstract

PURPOSE:To simply and inexpensively forge the forming part of high accuracy having no buckling, burr, etc., by forming the blank subjected to drawing by pressing it by the split die accompanied by the deformation of an upper die by bulging both end parts respectively by upper and lower punches with a die closing state. CONSTITUTION:The billet 102 of a bar-like blank is set among split blocks 78a-d in the closed forging device 10 composed of upper die 12 and lower die 14. Said split blocks 78a... are displaced by approaching each other by descending the die case 80 of a lower die 52 by the operation of the cylinder 20 of the upper die 12. Said billet 102 is thus elongated in the axial direction by pressing it to add drawing. Both end part of the blank 102 whose elongated part is constrained under the die closing state of the split blocks 78a... are formed by bulging it in the necessary shape by approaching a pair of upper and lower die punches 38, 76. In that case, the lower die punch 76 is preferably made in the structure of vertically moving by the operation of the rocking arm 58 having a supporting shaft 56. A performing part of high accuracy is thus forged by plastically deforming it with good balance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a closed forging method and an apparatus therefor, and more particularly, the present invention relates to a closed forging method and an apparatus for the same, and more particularly, for producing a long machine having a specific shape at both ends from a bar-shaped material by closed forging. The present invention relates to a closed forging method and apparatus for forging rough-forged products with high machining accuracy while ensuring a suitable molding balance and preventing the occurrence of buckling, cracking, etc. when molding into parts.

[Background of the Invention] For example, in internal combustion engines, when manufacturing important parts that require strength, such as connecting rods that connect pistons and crankshafts, forging is performed.

Conventionally, in the case of such forging, a round bar material is rough-processed by roll processing or the like, and then the rough-processed product is pressed with a forging die to form a desired shape.

However, when forming with a forging die, a part of the material is inserted into the joint of the forging die as a gap. Since a trimming process is required in the next step to punch out this edge, not only does the number of man-hours increase, but the workpiece that has gone through the trimming process also has unfinished marks, making it impossible to maintain high processing accuracy. .

Therefore, in recent years, various processing methods using closed forging have been proposed. The technical idea related to this closed forging is disclosed in, for example, Japanese Patent Application Laid-Open No. 56-128636 and Japanese Patent Application Laid-Open No. 56-1286.
37, JP 59-133928, JP 60-49824, JP 60-1022
43, JP 60-102246, JP 60-247432, JP 62-137
Publication No. 135, Japanese Utility Model Application No. 60-28937, Publication No. 60-42426, Publication No. 60-1156
It has been disclosed in Publication No. 50 and the like.

In this type of closed forging technology, a material is sandwiched between split dies, and a punch is pushed from the outside into the material closed in the split dies to cause plastic flow in the material, shaping the material into the desired shape. It is forged and formed. According to such closed forging, it is possible to suppress the occurrence of cracks during forming,
In addition, there are advantages such as being able to reduce the number of processing steps (Japanese Patent Laid-Open No. 56-128636, Japanese Patent Laid-Open No. 56-128637, Japanese Patent Laid-Open No. 59-1339).
(See Japanese Patent Application Laid-Open No. 60-49824).

By the way, the connecting rod that engages with the crankshaft that constitutes the engine has a long connecting rod portion that is I-shaped or eight-shaped in cross section, and a large end portion and a small end portion that are respectively bulged at both ends of the connecting rod portion. It is characterized by the shape of each part.

When such a connecting rod is manufactured by the closed forging, for example, a round bar-shaped material is hermetically sealed in a pair of split molds, and then a punch is introduced into the split molds from the outside to apply a predetermined plastic deformation to the material. . ``In other words, the connecting rod part is formed by pressing the side of the material with a punch.
In order to bulge the large and small ends of the connecting rod, the material is pressed with a punch from the axial direction.

In such a case, if the material is not completely restrained by the split die, buckling will occur in the material when the punch is swaged from the axial direction, and the flesh of the material will become crispy in the gap between the split dies. This causes the inconvenience of having to plug it in. In addition, since the volume distribution of connecting rods is different for each part of the large end, connecting rod, and small end, it is difficult to balance the flow of the flesh during molding, which often results in molding defects such as underfill and cracks. The problem is that it is easy to occur.

On the other hand, when considering the balance of forming, this is reflected in the mechanism of the equipment applied to the forging process. In fact, various closed forging devices equipped with double-acting mechanisms capable of applying force to the material from two different directions, such as split dies and punches, have been proposed (Japanese Patent Application Laid-Open No. 59-1339
28, JP 60-28937, JP 60-42426, JP 60-49824
(see publication). When realizing such complex forming, the timing of the operation of a pair of punches that enter from the axial direction of the material, the split type that presses the material from a direction different from this punch, or the linked operation with the punch must be adjusted to the forming balance. This must be carried out appropriately, making the mechanism complicated. Therefore, the forging device becomes larger and more expensive, and the manufacturing cost inevitably increases accordingly.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned disadvantages. When processing by forging, the material is drawn under the pressure effect of a split die as the upper die is displaced, and then an upper punch and a lower punch are applied, respectively, while the material is completely restrained by the split die. By independently pressing and bulging both ends of the material into the desired shape, buckling, cracking, etc. can be avoided, and plastic deformation can proceed in a well-balanced manner without applying excessive deformation to the material. Moreover, the upper punch,
It is an object of the present invention to provide a closed forging method and an apparatus thereof, which make it possible to achieve the operation of a lower punch with a relatively simple mechanism consisting of a substantial single-action mechanism rather than a double-action mechanism.

[Means for Achieving the Object] In order to achieve the above-mentioned object, the present invention provides a blockage method in which a rod-shaped material is closed with a plurality of split dies, and a punch is entered from the outside to form the material into a desired shape. The forging method includes a first step of placing a material between split dies, and pressing the material while displacing the split dies close to each other from a direction perpendicular to the axis of the material to create an axis of the material. a second step of adding drawing forming to stretch the material in the direction; and after the drawing by the split die is completed, the stretched portion of the material is restrained under the clamping state of the split die, and a pair of punches are applied to each of the materials. It is characterized by comprising a third step of entering the material from both end sides and expanding and molding both ends of the material into a desired shape.

The present invention also provides a closed forging method in which a set of punches enters a bar-shaped material from the outside into a state in which the material is closed by a plurality of divided dies to form the material into a desired shape, the method comprising: A first step is to hold the material at a predetermined forming position through one of the punches in a set of punches, which is supported in a floating manner so as to be freely displaceable downward; a second step of squeezing and stretching the material in the axial direction while displacing them close to each other, and lowering the one punch as the material stretches; A third step of inserting each of the pair of punches from both ends of the material under the clamped state of the split die to bulge both ends of the material into a desired shape. Features.

Further, in the present invention, in the first step, the connecting rod portion is formed as a roughly punched connecting rod product, and then, in the second step, the small end portion as the connecting rod roughly punched product is expanded using one of the punches supported in a floating manner. It is characterized in that it is extruded and the other punch is used to bulge the large end.

Further, in the present invention, the upper mold is disposed via an upper mold main body and a hydraulic cushion mechanism that is relatively displaced with respect to the upper mold main body. and an upper die punch that is integrally displaced with the upper die main body, and the lower die is elastically biased upward by a cushion means provided on the lower die, and as the upper die is displaced downward. between a die case that descends under the pressing action of the upper die, a plurality of divided dies that are housed in the goose case and whose opposing surfaces are displaced in a direction in which the diameter of each die is reduced as the goose case descends; In a forging device consisting of a lower die punch which is supported by a 70-ring so as to be freely displaceable downward so that its tip enters, the swing arm is pivotably attached to the lower die body and the upper die body. By descending, the lower die punch is moved through a rod that comes into contact with the upper die body and engages with one end of the swinging arm, and an elastic member disposed and internally installed at the other end of the swinging arm. A punch biasing means consisting of a punch support member provided with floating support is provided, and when the rod comes into contact with the upper mold body, the swinging arm is rotated, and the lower mold punch is displaced upward via the punch support member. It is characterized by having been configured.

Furthermore, the present invention is characterized in that the swinging arm has a substantially circular cross section, and is configured to swing while abutting against the lower mold body using the arcuate outer circumferential surface of the arm as a sliding surface.

[implementation! DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the closed forging method according to the present invention will be described in detail in connection with an apparatus for carrying out the closed forging method, with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a closed forging device according to the present invention. This closed forging device 10 has an upper mold 1 that can be raised and lowered freely.
2 and a fixed lower mold 14.

The upper mold 12 includes an upper mold main body 16 and a hydraulically operated upper mold cushion mechanism 18 that is integrally provided with the upper mold main body 16. The upper mold cushion mechanism 18 is provided inside the upper mold main body 16. will be provided.

First, this upper mold cushion mechanism 18 includes a cylinder 20,
It consists of a piston 22 that is slidably fitted into the cylinder 20, and an annular cylinder chamber 24 is defined between the cylinder 20 and the piston 22.

The hydraulic oil in this cylinder chamber 24 is led out from a vent line (not shown) via a control valve or the like when the cushion functions, and as a result, the piston 22 is configured to retire. Further, an upper die 26 for pressing a goo case, which will be described later, is fixed to the tip of the piston 22.
A hole 28 is bored in the center of the upper die 26.

The upper die 26 also includes a pressing block 30, which will be described later.
is movably attached. The pressing block 30 is always urged downward via the spring receiver 34 by the elastic force of the coil spring 320, and is always in contact with a dividing die, which will be described later, to press it downward.

On the other hand, an upper die punch 38 is attached to the tip of a back plate 36 which is integrally connected to the upper die body 16 and into which the piston 22 is fitted so as to be inserted into the hole 28 formed in the upper die 26. be done. Further, a substantially cylindrical pressing member 40 is attached to a predetermined portion of the lower edge of the upper mold body 16. This pressing member 40 has the function of urging a lower die punch drive mechanism, which will be described later.

Next, the lower mold 14 includes a lower mold main body 50 and a lower mold main body 50.
a lower die 52 placed on the upper die body 16; and a lower die punch drive mechanism 54 which is biased by the pressing member 40 and displaces the lower die punch described later upward as the upper die main body 16 moves downward.
It basically consists of.

First, a swinging arm 58 is pivotally attached to one lower end of the lower die main body 50 via a support shaft 56 .

One end side of this swing arm 58 is connected to the tip of a rod 60 via a pin 62. In this case, the rod 60 is elastically biased upward by a coil spring 64 that engages with its base end. Further, one end of the swinging arm 58 close to the pin 62 has a semicircular cross section and a pressing shaft 68 that extends vertically via a first sliding body 66 that is slidable along its circumferential surface. It is attached to. The tip of this pressing shaft 68 comes into contact with the suppressing member 40 provided on the upper mold body 16 as the upper mold body 16 descends.

On the other hand, a first sliding body 66 is provided at the other end of the swing arm 58.
Similarly, a second sliding body 70 having a semicircular cross section is mounted, and a punch support member 72 is mounted on the flat surface of this second sliding body 70. In this case, a coil spring 73 is installed inside the punch support member 72, and the lower die punch 76
is supported.

The lower die punch 76 is installed so that its tip faces inside the lower die 52.

Here, the lower mold die 52 is composed of four divided diamonds 8a to 78d and a die case 80 in which the divided diamonds 8a to 78d are housed, and which displaces these in the direction of making them approach each other. case 80
A plurality of cushion means 82 are provided in the lower die main body 50.
It is always elastically biased upward. That is, this cushion means 82 is composed of a pressing pin 84 and a coil spring 86 that is engaged with the pressing pin 84. When the coil spring 860 is activated, the pressing pin 84 comes into contact with the bottom surface of the die case 80. Press upward.

On the other hand, FIG. 2 shows details of the divided diamonds 8a to 78d. That is, a forming portion 88 corresponding to the shape of the workpiece is defined by the opposing surfaces of the split diamonds 8a to 78d, and the opposing surfaces of the split diamonds 8a to 78d defining the forming portion 88 are formed by the opposing surfaces of the connecting rod. It is formed into a shape that corresponds to a rough molded product. In this case, protrusions 87 are formed on the curved surfaces of the split dies 78a and 78c among the split diamonds 8a to 78d, and the split diamonds 8b,
Relatively long protrusions 89 are formed on each of the portions 78d.

On the other hand, on the rear surface of the split diamonds 8a to 78d, there are inclined surfaces 90a to 90d whose diameter increases downward. Shadows are formed. On the other hand, these inclined surfaces 90a to 90d
Similarly, sloped surfaces 92a to 92d whose diameter increases downward are formed on four inner surfaces of the die case 80 which slides along the diagonals 8a to 78d, respectively. Guides 194a to 94d are formed along the inclined surfaces 90a to 90d of each of the divided diamonds 8a to 78d, and protrude from both sides thereof. The guide grooves 96a to 96d into which the die case 80 is slidably fitted
is defined on both sides of the inclined surfaces 92a to 92d.

Note that reference numeral 98 indicates a knockout pin.

This knockout pin 98 is configured to be freely displaceable in the vertical direction via a drive means (not shown), and has the function of causing the pin 100 to protrude toward the punch support member 72 side.

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

In FIG. 3, reference numeral 102 indicates a round bar-shaped billet as a raw material, and reference numeral 104 indicates a connecting rod formed by subjecting the billet 102 to rough forging by a closed forging method which will be detailed below. Shows a rough molded product. This rough punched molded product 104 is subjected to finishing processing in the next step to be processed into a connecting rod as a finished product. In this case, the rough-beating molded product 104 includes a continuous rod portion 106 that is long and has a linear cross section;
A small end portion 108 that bulges out relatively small on one end side, a semicircular recessed portion, and a large end portion 110 that bulges out while being displaced in the axial direction are formed. .

Therefore, as shown in FIG. 1, the billet 102 heated to a high temperature is placed in the forming portion 88 between the split diamonds 8a to 78d so that one end of the billet 102 comes into contact with the tip of the lower die punch 76.
position within. At this time, the lower end of the lower die punch 76 is connected to the punch support member 7 constituting the lower die punch drive mechanism 54.
The lower die punch 76 is in a so-called floating state, separated by a predetermined distance from the tip of the lower die 76 via the press pin 74, and therefore, the lower die punch 76 is freely displaceable not only upward but also downward.

Next, the upper mold 12 is displaced downward, and the upper surface of the die case 80 surrounding the split diamonds 8a to 78d is removed via the upper mold die 26 disposed at the tip of the piston 22 constituting the upper mold cushion mechanism 18. is pressed so as to be displaced downward against the elastic force of a coil spring 86 constituting a cushion means 82 provided on the lower die 14.

The die case 80 receives the pressing action of the upper mold die 26 as the upper mold 12 moves downward, and slides along the inclined surfaces 90a to 90d formed at the rear portions of the divided dies 78a to 78d. At this time, the outer surface of the die case 80 is in contact with the lower mold body 50 and is only allowed to be displaced vertically downward, so as the die case 80 is displaced downward, the divided diamonds 8a to 78d are moved horizontally. They are subjected to the action of being displaced close to each other. Therefore, the split diamonds 8a to 78d are displaced toward each other, and in the molding section 88 between them, the billet 102 sandwiched between the split diamonds 8a to 78d begins to be pressed from a direction perpendicular to its axial direction. (See Figure 6a).

When the die case 80 is further lowered, the billet 102 is extended vertically along its axis. That is, as shown in FIG. 4 and FIG.
In FIG. 6, it is pressed against protrusions 89 (see FIG. 2) formed on the dividing diamonds 8b, 78d shown by mesh. As a result, the center portion of the billet 102 is squeezed and the meat flows in the direction extending in the axial direction. Since the upper end of the billet 102 is a free end, the upward flow of the meat is not hindered, while the lower end, which contacts the lower punch 76, moves the lower punch 76 as the meat flows downward. The punch support member 72 is pressed down against the pressing pin 74 which is biased by the elastic force of the coil spring 73 installed inside the punch support member 72.

When the bottom surface of the die case 80 comes into contact with the lower mold body 50, mold clamping of the split diamonds 8a to 78d is completed, and the split guides 78a to 78 against the billet 102 are
The drawing process in step d is completed (see Figure 6).

After this, when the upper mold 12 is further lowered, the stroke of the piston 22 becomes shorter as the hydraulic oil in the cylinder chamber 24 is discharged through a vent line (not shown), as shown in FIG. It functions as a cushion.

Therefore, as a result of the downward displacement of the upper mold main body 16 relative to the piston 22, the pressing member 40 disposed on one end side of the lower surface of the upper mold main body 16 eventually moves to the pressing shaft 68 disposed on the lower mold 14. until it comes into contact with the tip of the The swinging arm 58, which is connected to the pressing shaft 68 via the first sliding body 66, is rotated in the direction of arrow A from the support shaft 56 as a starting point against the elastic force of the coil spring 640. Therefore, the punch support member 72 connected via the second sliding body 70 on the other end side of the swing arm 58 is displaced upward,
This punch support member 72 urges the lower die punch 76 to be displaced upward. As a result, as shown in FIG. 6, the lower die punch 76 performs upsetting of the lower end of the billet 102, and the lower end of the billet 102 bulges out.

Furthermore, at the same time, the upper die punch 38, which is integrally attached to the back plate 36 with the upper die main body 16, enters the molding part 88 between the split diamonds 8a to 78d, and the upper end of the billet 102. Execute upsetting on the part. At this time, the upper punch 38 works together with the upsetting process by the lower punch 76 to crush the upper end of the billet 102, and the upper end of the billet 102 is largely plastically deformed. An undercut portion is formed on the side of the billet 102 by the protrusion 87 formed in the billet 102 . Finally, the molded portion 88 between the split diamonds 8a to 78d is filled with the flesh of the billet 102, and is processed into the shape of the rough-shot connecting rod molded product 104 shown in FIG. 3 (FIG. 6C). reference).

According to the closed forging method according to the present embodiment, the divided diamonds 8a to 78d are displaced close to each other by lowering the upper mold 12, and the billet 102 is squeezed to form the continuous rod portion 106 of the rough-forged product 104. The processing applied to stretch the billet in the direction ends when the split diamonds 8a to 78d are clamped, and then the billet 102 is completely restrained by the split guides 78a to 78d, and then the upper die punch 38 enters the billet. Since the upsetting process by pushing and the entry of the lower die punch 76 is started, and the large end 110 and small end 108 of the roughly punched product 1040 are formed, problems such as buckling may occur in the billet 102. The molding process proceeds smoothly without any problems.

Further, when the billet 102 is stretched in the axial direction by the diameter reduction action of the split diamonds 8a to 78d, the lower end of the billet 102 is in a state of being floatingly supported by the punch support member 72, so that the lower end of the billet 102 is The flow of the meat is not obstructed, and therefore, it is possible to avoid the inconvenience of a portion of the meat being inserted into the gaps between the dividing diamonds 8a to 78d. In addition, a balanced flow of the meat is promoted as a whole. In particular, when the connecting rod has a shape that bulges out at both ends, and the volume distribution at both ends is different, the effect of floatingly supporting the lower end of the billet 102 is remarkable, and the processing accuracy is improved. We can expect improvement.

After completing the molding of the billet 102 in this way, the upper die 12
Raise and open the mold. At this time, the pressing block 30 that is attached to the tip of the piston 22 via the upper die 26 is urging the divided diamonds 8a to 78d downward under the force of the coil spring 320, so that the pressing block 30 is When the upper die main body 16 starts to rise, the split diamond 8a
It comes into contact with the upper surface of 78d and presses it downward.

At this time, the die case 80 surrounding the divided gouies 78a to 78d is urged upward by the pressing pin 84 under the force of the coil spring 860 of the cushion means 82 provided on the lower mold 14, so that the In order to release the close contact between the divided diamonds 8a to 78d and the die case 80, a force acts in a direction to separate the divided diamonds 8a to 78d and the die case 80, respectively. Therefore, as the upper mold body 16 rises, the die case 80 is displaced upward through the elastic force of the coil spring 86, and at this time, the guide grooves 96a to 96d formed on the inner surface of the die case 80
The guide portions 94a to 94d of the divided guides 78a to 78d engage with the divided diamonds 8a to 7.
8d are displaced in the direction of separating them from each other.

In addition, as the upper mold body 16 is displaced upward, the pressing member 40 of the upper mold body 16 that was in contact with the pressing shaft 68 is separated, so that the rod 60 is displaced upward under the elastic force of the coil spring 64 and oscillates. The movable arm 58 swings in the direction of arrow B using the support shaft 56 as a fulcrum. As a result, the swing arm 58 returns to the initial state shown in FIG. after that,
By displacing the knockout pin 98 upward, the pin 10
0, the punch support member 72 and the lower die punch 76 are displaced upward, and the rough punched molded product 104 between the split diamonds 8a to 78d can be taken out. This rough punched molded product 104 is subjected to finishing processing in the next step, and is processed into a connecting rod in the final product shape.

Next, FIG. 7 shows another embodiment of the closed forging apparatus 10. In this case, the same constituent elements as in the first embodiment will be given the same reference numerals and detailed explanation thereof will be omitted.

In this case, as shown in the figure, this closed forging device 120
In this embodiment, a design change is made to the lower die punch drive mechanism 54 of the first embodiment. That is, in the case of the lower die punch drive mechanism 122 according to the second embodiment, one end of the flat upper surface of the sliding arm 124, which has a substantially semicircular shape and is swingable to slide with the lower die body 50 on its circumferential surface. part and pressing shaft 6
8 are in contact with each other via the first sliding body 66, and the sliding arm 1
The other end of the upper surface of 24 is configured to abut against a punch support member 72 via a second sliding body 70. In this case, since the sliding arm 124 receives the load accompanying the displacement of the upper mold body 16 along its circumferential surface, unlike the case in which the support shaft 56 supports the swinging arm 58 in the first embodiment,
It becomes possible to reduce the load burden. Therefore,
It is understood that compared to the first embodiment, the design does not require much sophistication, and the processing rate is relatively high (therefore, it is suitable for manufacturing products that place a large load on the equipment). It will be.

Furthermore, it goes without saying that the series of forging steps described above can be performed in the same manner by applying this closed forging device 120.

[Effects of the Invention] As described above, according to the present invention, a material is sandwiched between a plurality of divided dies, and the divided dies are displaced in the direction of approaching each other along with the displacement of the upper mold, and the material is After the material is squeezed and stretched, an upper die punch and a lower die punch are respectively advanced with the displacement of the upper die into the state in which the material is restrained between the split dies, and upsetting of both ends of the material is performed. Molding is in progress. Therefore, problems such as buckling that occur during upsetting can be prevented. In addition, in particular, if the lower die punch is brought into contact with the material in a floating state to absorb the downward stretching when the material is squeezed, then the lower die punch can be moved in to avoid unreasonable strain during the process of plastic deformation of the material. The effect that meat flow does not occur and the processing accuracy can be improved is obtained.

Furthermore, in a forging device that performs such a series of forging processes, the displacement of the split die and the operation of the upper die punch and the lower die punch are both linked to the lowering of the upper die, and are performed through a mechanical mechanism. Therefore, it is only necessary to provide the upper die with a cushion mechanism consisting of a hydraulic cylinder or the like, and the action of a double-acting mechanism can be achieved by a substantial single-acting mechanism. For this reason,
The configuration of the forging device itself is relatively simplified, and the forging device can be manufactured at low cost.

Therefore, it has a remarkable effect on improving the production efficiency of the forging process as a whole and reducing its manufacturing cost.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a partially omitted cross-sectional explanatory diagram showing the structure of a closed forging device according to the present invention, and Fig. 2 is a structure of a split die and a die case constituting the closed forging device according to the present invention. FIG. 3 is a perspective view showing the shape of a billet and a rough formed product used when manufacturing a connecting rod in the closed forging method according to the present invention, and FIGS. 4 and 5 are FIG. 6 is a diagram explaining the operation of the closed forging device; FIG. 6 is a diagram explaining a series of steps of the closed forging method according to the present invention; FIG. 7 is a diagram explaining another embodiment of the closed forging device according to the present invention. It is a partially omitted cross-sectional explanatory diagram. 10... Closed forging device 12... Upper die 14
...Lower mold 16...Upper mold main body 18
...Upper cushion mechanism 20...Cylinder 22
... Piston 26 ... Upper die 30
...Press block 38...Upper die punch 5
0... Lower die body 52... Lower die 5
6...Support shaft 58...Swing arm 66.70...Sliding body 68...Press shaft 72...Punch press member 76...Lower mold punches 78a to 78d...Divided block 80・・・
・Die case 102...Billet 104...Rough-molded product

Claims (5)

[Claims] (1) A closed forging method in which a rod-shaped material is closed between a plurality of split dies and a punch is inserted from the outside to form the material into a desired shape. a second step of applying drawing forming to the material by pressing the material while displacing the dividing dies close to each other from a direction perpendicular to the axis of the material and stretching the material in the axial direction; After drawing is completed, the stretched portion of the material is restrained under the clamping state of the split die, and a pair of punches are entered into the material from both end sides to shape both ends of the material into the desired shape. A closed forging method characterized by comprising a third step of expansion forming. (2) A closed forging method in which a set of punches enters a rod-shaped material from the outside into a state in which the material is closed with a plurality of divided dies to form the material into a desired shape, and the material is formed into a desired shape. A first step is to hold the material in a predetermined forming position through one of the punches in the set, which is supported floatingly so as to be freely displaceable downward; a second step of squeezing and stretching the material in the axial direction while displacing the material in close proximity, and lowering the one punch as the material stretches; a third step of inserting each of the pair of punches from both end sides of the material under the mold clamping state to perform molding to bulge both ends of the material into a desired shape. Closed forging method. (3) In the method according to claim 2, in the first step,
The connecting rod part as the connecting rod rough formed product is formed, and then, in the second step, the small end as the connecting rod rough formed product is bulged with one punch supported by floating, and the large end is formed with the other punch. A closed forging method characterized by bulging a portion. (4) The upper mold includes an upper mold main body, an upper mold die disposed via a hydraulic cushion mechanism that is displaced relative to the upper mold main body, and an upper mold punch that is integrally displaced with the upper mold main body. The lower die is resiliently biased upward by a cushion means provided on the lower die, and a die case that descends under the pressing action of the upper die as the upper die is displaced downward; A plurality of divided dies are housed in a die case and are displaced in a direction in which their respective opposing surfaces are reduced in diameter as the die case is lowered, and a floating unit that is freely displaceable downward so that its tips enter between the divided dies. In a forging device, the forging device includes a supported lower die punch, a swinging arm pivotally attached to the lower die body, and an upper die body that comes into contact with the upper die body when the upper die body is lowered, and the swing arm providing a punch biasing means consisting of a rod that engages on one end side and a punch support member that floatingly supports the lower die punch via an internal elastic member disposed on the other end side of the swing arm; A closed forging device characterized in that the rod contacts the upper die main body to rotate the swinging arm and displace the lower die punch upward via the punch support member. (5) In the device according to claim 4, the swinging arm has a substantially circular cross section, and is configured to swing while abutting against the lower mold body using the arcuate outer peripheral surface of the arm as a sliding surface. Features a closed forging device.