JP2014237140A - Forging metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forging metal mold in which a metal can be prevented from being inserted in a knockout pin outer peripheral gap.SOLUTION: A tip 31 of a knockout pin 3, which is so received in a pin hole 12 of one metal mold 1 of a pair of metal molds as to be capable of projecting, is so formed as that the a dimension of the tip in an outer diameter direction increases in association with approaching a tip side. An opening side end part 13 of the pin hole 12 is so formed corresponding to the tip 31 of the knockout pin 3 that a dimension of the end part 13 in an inner diameter direction increases in association with approaching the opening side. By a pressure of a forging raw material which plastically flows, an outer peripheral surface 311 of the tip of the knockout pin 3 is pressure-welded to an inner peripheral surface 131 of the opening-side end part of the pin hole 12.

Description

  The present invention relates to a forging die in which a forged product after molding is protruded from a die by a knockout pin and related technology.

  In the mold for die forging process, in which the upper die is driven into the lower die on which the forging material is set and the forging material is plastically deformed to form a forged product. The forged product that is in close contact with the lower die is pushed up by a knockout pin and discharged from the lower die.

  In a forging die, for example, a knockout pin is placed in a molding recess of a lower die, and the forging die molding part is pushed up and discharged by the knockout pin, or the knockout pin is lowered into the lower die. The burrs of the forged product are pushed up by the knockout pin and discharged at the peripheral edge of the opening (deburring portion) of the molding recess in the mold.

  In the forging die, the knockout pin is accommodated in a pin hole provided in the lower die so as to be protruded. Usually, the inner peripheral edge portion of the pin hole in the lower die and the outer peripheral edge portion of the tip end of the knockout pin are used. A gap is formed between them. For this reason, at the time of forging, so-called metal insertion occurs in which a forging material (metal) that plastically flows flows into the gap (pin outer circumferential gap).

  When such metal insertion occurs, the burr due to the metal insertion may stick to the lower mold, and in that case, the forged product (product) may not be smoothly discharged from the lower mold, producing There is a possibility of trouble. Even if the forged product can be discharged from the lower mold, if the burr due to insertion is large, there may be a conveyance trouble or processing trouble in the next process. To avoid such trouble, A separate process is required, which may reduce productivity.

  Under such circumstances, a forging die for the purpose of preventing metal insertion has been proposed.

  For example, in the forging die shown in Patent Document 1 below, a burr portion of a forged product is pushed up by a knockout pin, and the forged product is discharged from the die. In this forging die, the tip end surface of the knockout pin is formed into a convex spherical surface, and a part of the tip end portion of the pin protrudes from the pin hole. Then, the metal flowing in the vicinity of the tip of the pin at the time of forging is moved along the convex spherical surface of the tip of the pin so that the metal can be circulated smoothly. As a result, the metal is prevented from flowing into the pin outer peripheral gap and the insertion of the metal is prevented.

JP-A-8-66737

  However, the forging die shown in Patent Document 1 also has a problem in that it is not possible to reliably prevent insertion of metal into the pin outer peripheral gap, and excessive burrs are generated in the forged product.

  This invention is made in view of said subject, and it aims at providing the forging die which can prevent the insertion of the metal to the clearance gap of a knockout pin outer periphery, and its related technique.

  In order to achieve the above object, the present invention provides the following means.

[1] A pair of dies for plastically deforming a forging material to form a forged product, and a knockout pin accommodated in a pin hole of one of the pair of dies so as to protrude, A forging die in which a knockout pin is projected so that a molded forged product is projected from the one die,
While the tip of the knockout pin is formed so that the dimension in the outer diameter direction increases as it goes to the tip,
The opening side end of the pin hole is formed so that the dimension in the inner diameter direction becomes larger toward the opening side corresponding to the tip of the knockout pin,
A forging die, wherein the outer peripheral surface of the tip end portion of the knockout pin is brought into pressure contact with the inner peripheral surface of the opening side end portion of the pin hole by the pressure of the forging material that plastically flows.

[2] The tip outer peripheral surface of the knockout pin and the inner peripheral surface of the opening side end of the pin hole are formed in an inclined surface having a certain gradient,
The forging die according to the preceding item 1, wherein gradients on the outer peripheral surface of the tip end portion of the knockout pin and the inner peripheral surface of the opening side end portion of the pin hole are both set to the same angle.

  [3] The forging die according to item 2 above, wherein gradients of the outer peripheral surface of the tip end portion of the knockout pin and the inner peripheral surface of the opening side end portion of the pin hole are each set to 2 ° to 45 °.

  [4] Any of the preceding items 1 to 3, wherein the outer peripheral surface of the tip end portion of the knockout pin is pressed against the inner peripheral surface of the opening side end portion of the pin hole by the pressure of the forging material that plastically flows. The forging die according to item 1.

  [5] The forging die according to any one of items 1 to 4, wherein a tip end portion of the knockout pin and an opening side end portion of the pin hole are formed in a truncated cone shape.

[6] A gap is formed between the outer peripheral surface of the tip end portion of the knockout pin and the inner peripheral surface of the opening side end portion of the pin hole,
The forging die according to any one of the preceding items 1 to 5, wherein the knockout pin is retracted by a pressure of a forging material that plastically flows.

  [7] Any one of items 1 to 5 above, wherein the outer peripheral surface of the tip end portion of the knockout pin is in contact with the inner peripheral surface of the opening side end portion of the pin hole in a state where the pressure of the plastic flowing forging material is not applied. The forging die described in 1.

[8] The one mold has a forming recess for forming a forged product,
The forging die according to any one of the preceding items 1 to 7, wherein the knockout pin is disposed at the bottom of the molding recess.

  [9] The forging die according to any one of items 1 to 8, which is configured by a die for hermetic or semi-hermetic forging.

  [10] In any one of the preceding items 1 to 9, wherein a pressure receiving recess is formed on a tip surface of the knockout pin, and an outer wall of the pressure receiving recess is configured to be elastically deformable by pressure of a forging material that plastically flows. The forging die described.

  [11] The forging die according to the above item 10, wherein an inner peripheral surface of the pressure receiving recess is constituted by a concave spherical surface.

[12] The forging material is clamped by a pair of molds, and the forging material is plastically deformed to form a forged product. On the other hand, the forging material is provided so as to protrude into a pin hole of one of the pair of molds. A forging method in which the knockout pin is protruded and the molded forged product is protruded from the one mold,
While forming the tip of the knockout pin so that the dimension in the outer diameter direction increases toward the tip side,
The opening side end portion of the pin hole is formed so that the dimension in the inner diameter direction becomes larger toward the opening side corresponding to the tip portion of the knockout pin,
A forging method, wherein the outer peripheral surface of the tip end portion of the knockout pin is brought into pressure contact with the inner peripheral surface of the opening side end portion of the pin hole by the pressure of the forging material that plastically flows.

  According to the forging die according to the invention [1], when the knockout pin is pushed in by the pressure of the metal constituting the forging material, the outer peripheral surface of the tip end portion of the knockout pin comes into pressure contact with the inner peripheral surface of the upper end portion of the pin hole. Thus, the pin outer peripheral gap is closed. For this reason, it can prevent that a metal flows in into a pin outer periphery clearance gap, and can prevent that insertion of a metal arises.

  According to the forging die according to the invention [2], when the knockout pin is pushed in by metal pressure, the outer peripheral surface of the tip end portion of the knockout pin can be brought into surface contact with the inner peripheral surface of the upper end portion of the pin hole. For this reason, a pin outer periphery clearance can be more reliably obstruct | occluded and it can prevent more reliably that a metal flows in into a pin outer periphery clearance.

  According to the forging die concerning the said invention [3]-[5], said effect can be acquired more reliably.

  According to the forging die according to the above invention [6], in the natural state where the metal pressure is not acting, the pin outer peripheral gap is opened, so that unnecessary lubricant remaining in the die or in the die Unnecessary gas generated in the above can be discharged out of the mold through the pin outer peripheral gap.

  According to the forging die concerning the said invention [7]-[9], said effect can be acquired much more reliably.

  According to the forging die according to the invention [10] and [11], the outer wall of the pressure receiving recess provided at the tip of the knockout pin can be pressed against the inner peripheral surface of the upper end of the pin hole by the pressure of the metal. The pin outer peripheral gap can be more reliably closed.

  According to the said invention [12], the forging method which show | plays the same effect similarly to the above can be provided.

FIG. 1A is a cross-sectional view showing a forging die according to a first embodiment of the present invention in an open state. FIG. 1B is a cross-sectional view showing the forging die according to the first embodiment in a closed state. FIG. 2A is an enlarged cross-sectional view showing the periphery of the knockout pin of the lower die in the forging die of the first embodiment in a natural state. FIG. 2B is an enlarged sectional view showing the periphery of the knockout pin of the lower die in the first embodiment in a state during forging. FIG. 3 is a perspective view showing a knockout pin applied to the forging die of the first embodiment. FIG. 4 is a perspective view showing a knockout pin of a first modification applicable to the forging die of the present invention. FIG. 5 is a perspective view showing a knockout pin of a second modification applicable to the forging die of the present invention. FIG. 6 is an enlarged sectional view showing the periphery of the knockout pin of the lower die in the forging die according to the second embodiment of the present invention. FIG. 7A is an enlarged cross-sectional view showing a periphery of a knockout pin of a lower die in a forging die according to a third embodiment of the present invention in a natural state. FIG. 7B is an enlarged sectional view showing the periphery of the knockout pin of the lower die in the forging die according to the third embodiment of the present invention in a state during forging.

<First Embodiment>
1 and 2 are sectional views showing a forging die according to a first embodiment of the present invention. As shown in these drawings, the forging die according to the first embodiment is a lower die (die) 1 constituting one die and the other die and is provided with a forming load. A mold (punch) 2 is provided. This forging die is configured such that when the two dies 1 and 2 are matched (when the die is closed), the molding part is closed and hermetic forging is performed. Burr is hardly formed.

  Both molds 1 and 2 are made of, for example, a well-known steel for molds.

  The lower mold 1 is formed with a molding recess 11 for molding the forged product W. The upper end of the molding recess 11 is open on the upper side surface of the lower mold 1.

  The upper mold 2 is arranged so that its axis is along the vertical direction, and is arranged corresponding to the molding recess 11 of the lower mold 1. The upper die 2 is formed so that the cross-sectional shape of the tip (lower end) thereof corresponds to the cross-sectional shape of the molding recess 11 in the lower die 1. Further, the upper mold 2 can be moved up and down in the vertical direction (axial direction) by a lifting drive means (not shown). When the upper mold 2 is lowered, the lower end portion of the upper mold 2 is inserted into the molding recess 11, and the molding portion is formed by the lower end surface of the upper mold 2 and the inner peripheral surface of the molding recess 11. A (molding space) is formed. The inner peripheral surface shape of the molding part is formed corresponding to the outer peripheral surface shape of the forged product W to be molded.

  Therefore, when the forging material is inserted into the molding recess 11 and the upper die 2 is lowered and pressurizes the forging material, the forging product W is deformed by plastic deformation according to the molding part. Is to be molded.

  A pin hole 12 extending in the vertical direction is formed at the bottom of the molding recess 11 in the lower mold 1. The upper end of the pin hole 12 is opened upward at the bottom surface of the molding recess 11. In the present embodiment, the pin hole 12 is formed in an inverted frustoconical shape in which the dimension in the inner diameter direction gradually increases as the upper end portion 13 which is the opening side end portion moves upward (opening side). Further, the inner peripheral surface 131 of the upper end portion 13 in the pin hole 12 is formed in a tapered surface that is an inclined surface having a constant gradient θ1 with respect to the axis.

  Furthermore, the back part 14 which is a part below the upper end part 13 in the pin hole 12 is formed in a straight shape with a circular cross section having a constant inner diameter at any position in the vertical direction.

  As shown in FIGS. 1 to 3, the knockout pin 3 housed in the pin hole 12 is gradually removed as the tip end (upper end portion) 31 corresponding to the upper end portion 13 of the pin hole 12 moves upward (tip end side). It is formed in an inverted frustoconical shape in which the radial dimension increases. Further, the outer peripheral surface 311 of the tip 31 of the knockout pin 3 is formed into a tapered surface that is an inclined surface having a constant gradient θ2 with respect to the axis.

  In the present embodiment, the gradient θ2 of the outer peripheral surface 311 of the tip end portion of the knockout pin 3 is set to the same angle as the gradient θ1 of the inner peripheral surface 131 of the upper end portion of the pin hole 12.

  Moreover, the shaft part 30 which is a part below the front-end | tip part 31 in the knockout pin 3 is formed in the straight shape of circular cross section in which the outer diameter was formed uniformly in any position of an up-down direction.

  The knockout pin 3 is accommodated in a state in which the tip end portion 31 of the knockout pin 3 is made to correspond to the upper end portion 13 of the pin hole 13 while aligning the axial centers of the pinhole 12 with each other. The knockout pin 3 can be moved in the axial direction (vertical direction) with respect to the pin hole 12. Further, the knockout pin 3 can be slid upward by driving means such as a cylinder (not shown). Then, as will be described later, when the knockout pin 3 moves upward and the tip portion 31 of the pin 3 jumps into the molding recess 11 of the lower mold 1, the forged product W in the molding recess 11 is pushed up to lower the lower metal The mold 1 is discharged.

  In the first embodiment, the knockout pin 3 is lower (base end side) due to the metal pressure P when the metal (metal material) constituting the forging material plastically flows during forging as will be described later. ) To move a small amount downward (retract). In the present embodiment, when the knockout pin 3 is released from the metal pressure P, it returns to its original position.

  In the first embodiment, in a natural state in which the metal pressure P during forging is not applied, between the tip outer peripheral surface 311 of the knockout pin 3 and the upper peripheral inner peripheral surface 131 of the pin hole 12, A gap (clearance) 35 is formed. In the present embodiment, the gap 35 is sometimes referred to as a pin outer peripheral gap or a pin outer peripheral clearance.

  In the present embodiment, the gap 35 is set at a constant interval throughout the entire outer peripheral surface 311 of the tip end portion of the knockout pin 3.

  In this embodiment, the tip end surface (upper end surface) of the knockout pin 3 is formed as a flat surface, and the tip end surface of the knockout pin 3 is the opening surface of the pin hole 12 in a natural state where no metal pressure P is applied. It is arranged corresponding to. In other words, the tip surface of the knockout pin 3 constitutes a part of the inner peripheral surface of the molding space (cavity).

  Next, a forging method using the forging die according to the first embodiment will be described. Examples of the forged product W formed by the forging die according to the present embodiment include a double-headed piston as a part of a compressor for a car air conditioner.

  In the initial state before the forging process starts, the upper die 2 is in a raised state (die opening state). Further, the knockout pin 3 is in a non-projecting state, that is, is immersed (retracted) into the pin hole 12, and the tip end surface of the pin is arranged corresponding to the bottom surface of the molding recess 11.

  In this state, a lubricant is applied to required portions of the lower mold 1 and the upper mold 2, and a forging material is set in the molding recess 11 of the lower mold 1.

  Here, in the present embodiment, examples of the lubricant include water-based lubricants and oil-based lubricants.

  Forging materials include those produced by cutting aluminum (including aluminum alloys) continuous castings into a predetermined length, etc., and aluminum powder is compressed into billets and then hot extruded. It is possible to use those manufactured by a method such as forming into a round bar shape by cutting the extruded material into a predetermined length. In addition, extruded materials, rolled materials, and the like can be used as the forging material.

  The forging material, the lower mold 1 and the upper mold 2 are preheated to a predetermined temperature as necessary.

  After setting the forging material in the molding recess 11 of the lower mold 1, the upper mold 2 is lowered and driven into the molding recess 11 to close the mold. Pressurize to high load. As a result, the forging material is plastically deformed into a shape corresponding to the molding space, and the forged product W is formed.

  In the present embodiment, during this forging process (during the plastic deformation of the forging material), the plastically flowing metal (metal material) presses the tip surface of the knockout pin 3 in the molding recess 11. As a result, as shown in FIG. 2B, a great metal pressure P acts on the tip surface of the knockout pin 3, the knockout pin 3 is pushed downward, and the knockout pin 3 moves a small amount downward. In this way, the outer peripheral surface 311 of the tip end portion of the knockout pin 3 is pressed against the inner peripheral surface 131 of the upper end portion of the pin hole 12 to close the pin outer peripheral gap 35. For this reason, it can prevent that a metal flows in into the pin outer periphery clearance gap 35, and can prevent that insertion of a metal arises.

  In the present embodiment, the gradient θ2 of the tip outer peripheral surface 311 of the knockout pin 3 and the gradient θ1 of the inner peripheral surface 131 of the upper end portion of the pin hole 12 are set at the same angle. When the pin 3 is pushed in, the outer peripheral surface 311 of the tip end portion of the knockout pin 3 comes into surface contact with the inner peripheral surface 131 of the upper end portion of the pin hole 12 in a wide range, and the pin outer peripheral clearance 35 is closed. For this reason, it can prevent more reliably that a metal flows in into the pin outer periphery clearance gap 35, and can prevent that insertion of a metal arises more reliably.

  On the other hand, after the molding of the forged product W is completed, the upper mold 2 is raised and the mold is opened. In the state immediately after the mold opening, the forged product W is disposed in close contact with the inner peripheral surface of the molding recess 11 of the lower mold 1.

  Next, the knockout pin 3 is raised, the forged product W is pushed up (knocked out) by the knockout pin 3, and the forged product W is released from the lower mold 1 and discharged. The forged product W discharged from the lower mold 1 is carried out by a transfer device or the like (not shown).

  Here, in the present embodiment, as described above, insertion of metal during forging can be prevented, so that when the forged product 2 is knocked out from the lower mold 1, burrs due to insertion of metal are present in the lower mold 1. Therefore, it is possible to reliably prevent such a problem that the forged product W sticks to the lower die 1 and to smoothly discharge the forged product W from the lower mold 1. Furthermore, it is possible to reliably prevent the occurrence of transport troubles and processing troubles in the next process due to burrs caused by metal insertion, and productivity can be further improved.

  On the other hand, after the forged product W is carried out from the lower mold 1, the knockout pin 3 is lowered and returned to the initial position. The knockout pin 3 in this state does not receive the metal pressure P, and the knockout pin 3 is not pushed downward. Therefore, the pin tip surface is arranged so as to correspond to the opening surface of the pin hole 12.

  In the present embodiment, in a natural state where the metal pressure P is not received, a gap 35 is formed between the distal end outer peripheral surface 311 of the knockout pin 3 and the upper end inner peripheral surface 131 of the pin hole 12. For this reason, unnecessary lubricant remaining in the molding recess 11 and unnecessary gas generated in the molding recess 11 can be reliably discharged from the molding recess 11 to the outside via the pin outer peripheral gap 35. Therefore, it is possible to prevent unnecessary lubricant and gas from remaining in the molding recess 11, and it is possible to reliably prevent adverse effects caused by the residual.

  Here, in this embodiment, the gradient θ2 of the outer peripheral surface 311 of the tip end portion of the knockout pin 3 and the gradient θ1 of the inner peripheral surface 131 of the upper end portion of the pin hole 12 are 2 ° to 45 °, preferably 5 ° to 20 °. It is good to set. That is, when the gradients θ1 and θ2 are set within this range, when the knockout pin 3 is retracted by the metal pressure, the pin tip outer peripheral surface 311 can be reliably pressed against the pin hole upper end inner peripheral surface 131, The pin outer circumferential gap 35 can be reliably closed.

  In the present embodiment, the one-side interval (clearance dimension) A1 of the pin outer peripheral gap 35 is set to 0.01 mm to 0.2 mm, preferably 0.03 mm to 0.15 mm. That is, if this clearance dimension A1 is too large, the pin outer peripheral gap 35 cannot be reliably closed during the forging process, and metal may flow into the gap 35 to cause metal insertion. It is not preferable. Conversely, when the clearance dimension A1 is too small, the pin outer peripheral gap 35 in the natural state where the metal pressure P is not applied becomes too narrow, and unnecessary lubricant and gas cannot be discharged from the gap 35. Unnecessary lubricant may remain, which is not preferable.

  In addition, in the said embodiment, although the pin front-end | tip part 31 and the pin hole upper end part 13 are formed in the inverted truncated cone shape, those shapes are not limited in this invention. For example, as shown in FIG. 4, the pin tip 31 may be formed in an inverted polygonal frustum shape such as an inverted quadrangular frustum shape. Similarly, the pin hole upper end portion 13 may be formed in an inverted polygonal frustum shape corresponding to the pin tip portion 31.

  Moreover, in the said embodiment, the whole peripheral surface of the pin front-end | tip part 31 is formed in an inclined surface, and the pin front-end | tip part outer peripheral surface 311 press-contacts to the upper end part internal peripheral surface 131 of the pin hole 12 in the perimeter at the time of forging. However, the present invention is not limited to this, and in the present invention, at least a part of the pin tip portion outer peripheral surface 311 may be configured to be in pressure contact with the pin hole upper end portion inner peripheral surface 131. For example, as shown in FIG. 5, in the knockout pin 3 having the tip portion 31 having a quadrangular cross section, only two directions out of the four surrounding directions at the pin tip portion 31 increase in the outer diameter direction toward the tip side. In the forging process, only two side surfaces of the peripheral four side surfaces of the pin tip portion 31 may be configured to be in pressure contact with the inner peripheral surface 131 of the pin hole upper end portion. Needless to say, the shape of the inner peripheral surface 131 of the upper end portion of the pin hole 13 may be formed corresponding to the shape of the outer peripheral surface 311 of the tip portion of the pin 3.

  Furthermore, in the present invention, the gradients θ1 and θ2 of the pin tip outer peripheral surface 311 and the pin hole upper end inner peripheral surface 131 are not necessarily set to be constant, and the gradients θ1 and θ2 may be changed in the middle.

  In short, it is only necessary that the pin tip 31 is formed so that the dimension in the outer diameter direction becomes larger toward the tip side (upper end side). Similarly, the pin hole upper end portion 13 only needs to be formed so that the dimension in the outer diameter direction becomes larger toward the opening side (upper end side).

  Further, in the above embodiment, the gradient θ2 of the pin tip outer peripheral surface 311 and the gradient θ1 of the pin hole upper end inner peripheral surface 131 are set to the same angle. However, the present invention is not limited to this, and in the present invention, the gradient You may make it set (theta) 1 and gradient (theta) 2 to a different angle. Even in this case, when the knockout pin 3 is retracted by the metal pressure P, at least a part of the pin tip outer peripheral surface 311 is in pressure contact with the pin hole upper end inner peripheral surface 131 to close the pin outer peripheral gap 35. Can do.

  Moreover, in the said embodiment, although the axial part 30 of the knockout pin 3 is formed in the column shape, the shape of this axial part 30 is not specifically limited in this invention. For example, the shaft portion 30 may be formed in a polygonal column shape such as a quadrangular column shape or a hexagonal column shape. Further, the shape of the shaft portion 30 does not necessarily correspond to the shape of the pin tip portion 31. For example, the pin tip portion 31 may be formed in an inverted truncated cone shape, and the shaft portion 30 may be formed in a polygonal column shape. good. Conversely, the pin tip portion 31 may be formed in a reverse polygonal frustum shape, and the shaft portion 30 may be formed in a cylindrical shape.

  Moreover, in the said embodiment, although the knockout pin 3 is arrange | positioned in the shaping | molding recessed part 11 of the lower metal mold | die 1, the position of the knockout pin 3 is not restricted to a shaping | molding recessed part. For example, in a mold for burr forming such as open forging, a knockout pin is arranged corresponding to the part where the burr is generated, and the burr part is pushed up and discharged by the knockout pin after molding. Also good. Needless to say, a knockout pin may be disposed in the molding recess even in a mold that performs burr out molding.

  However, since the present invention pushes the knockout pin 3 by the metal pressure P at the time of die matching, it is suitable for processing with a high metal pressure P, that is, hermetic or semi-hermetic forging.

Second Embodiment
FIG. 6 is a sectional view showing a lower die of a forging die according to the second embodiment of the present invention. As shown in the figure, in the forging die of the second embodiment, the outer peripheral surface of the tip end portion of the knockout pin 3 accommodated in the pin hole 12 of the lower die 1 in a natural state where no metal pressure is applied. No gap is formed between 311 and the upper end inner peripheral surface 131 of the pin hole 12, and the pin tip outer peripheral surface 311 is in contact with the pin hole upper end inner peripheral surface 131.

  In the forging die according to the second embodiment, other configurations are the same as those in the first embodiment, and therefore, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  In the forging die according to the second embodiment, when the knockout pin 3 is pushed downward due to the metal pressure acting on the distal end surface of the knockout pin 3 during forging, the outer periphery of the distal end portion of the knockout pin 3 The surface 311 is more strongly pressed against the inner peripheral surface 131 of the upper end portion of the pin hole 12. For this reason, it can prevent more reliably that a metal flows in into the clearance gap between the pin tip part outer peripheral surface 311 and a pin hole upper end part internal peripheral surface 131, and can prevent insertion of a metal more reliably.

<Third Embodiment>
7A and 7B are sectional views showing a lower die of the forging die according to the third embodiment of the present invention. As shown in both figures, in the forging die of the third embodiment, a pressure receiving recess 32 is formed on the tip surface of the knockout pin 3. The inner peripheral surface of the pressure receiving recess 32 is formed as a concave spherical surface whose center is located on the axis of the knockout pin 3 and whose radius of curvature is larger than the radius of the knockout pin 3. And the outer side wall (outer peripheral wall) 33 arrange | positioned at the outer periphery of the pressure receiving recessed part 3 is continuously formed in the circumferential direction along the outer peripheral part of the front end surface of the knockout pin 3. As shown in FIG.

  Further, the inner peripheral surface of the pressure-receiving recess 32 is formed into a concave spherical surface, so that the outer wall 33 has a distal end from the proximal end side so that the distal end side (upper end side) is thinner than the proximal end side (lower end side). It is formed so that the wall thickness gradually decreases toward the side.

  In the third embodiment, the outer wall 33 is configured to be elastically deformable so as to bend outward (outer diameter direction). And as will be described later, the outer wall 33 is elastically deformed outward by the pressure P of the metal constituting the forging material and is expanded and deformed (expanded deformation).

  In the normal state (the non-projecting state where the knockout pin 3 does not project from the pin hole 12), the tip end surface of the knockout pin 3 is arranged corresponding to the opening surface of the pin hole 12. In other words, the tip surface of the knockout pin 3 (the inner peripheral surface of the pressure receiving recess 32) constitutes a part of the inner peripheral surface of the molding space (cavity).

  In the third embodiment, as in the first embodiment, in the natural state where the metal pressure P during forging is not applied, the gap between the opening edge of the pin hole 12 and the outer periphery of the tip end surface of the knockout pin 3 is the same. A gap (clearance) 35 is formed on the surface.

  In the forging die according to the third embodiment, other configurations are substantially the same as those in the first embodiment, and therefore, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  In the forging die according to the third embodiment, after setting a forging material in the forming recess 11 and then driving the upper die 2 into the forming recess 11, the forging material is plastically deformed and a forged product W is formed.

  During this forging process, the tip surface of the knockout pin 3 is pressed by the metal pressure P, and the knockout pin 3 moves a small amount downward, as in the first embodiment. As a result, the pin tip outer peripheral surface 311 is pressed against the pin hole upper end inner peripheral surface 131 to close the pin outer peripheral gap 35, and the metal is prevented from flowing into the pin outer peripheral gap 35.

  Furthermore, in the third embodiment, since the pressure receiving recess 32 is formed on the tip surface of the knockout pin 3, the pressure receiving recess disposed on the outer peripheral edge of the pin tip surface by the metal pressure P during forging. The outer wall 33 of 32 tries to elastically deform outward. For this reason, the tip end portion of the outer wall 33 is more strongly pressed against the inner peripheral surface 131 of the pin hole upper end portion, so that the pin outer peripheral gap 35 is more reliably closed and the metal flows more reliably into the pin outer peripheral gap 35. Is prevented.

  Furthermore, in the third embodiment, since the pressure receiving recess 32 is formed on the tip surface of the knockout pin 3, the metal flows into the pressure receiving recess 32 during the forging process so that the pin outer clearance 35 is relatively moved. Metal inflow is reduced. Therefore, also in this respect, the inflow of the metal into the pin outer peripheral gap 35 can be reduced, and the occurrence of metal insertion can be prevented more reliably.

  In this embodiment, since the inner peripheral surface of the pressure receiving recess 32 at the tip of the pin is formed as a concave spherical surface, the metal stress acting on the pressure receiving recess 32 is distributed and received over the entire inner peripheral surface of the pressure receiving recess 32. be able to. That is, it is possible to prevent the metal stress from acting locally on any part of the pressure receiving recess 32. For this reason, it is possible to reliably prevent problems such as the outer wall 33 being damaged early, to sufficiently ensure the strength of the knockout pin 3, and to improve the durability.

  Further, in the present embodiment, the pressure receiving recess 32 is formed in a concave spherical shape, so that the thickness of the outer wall 33 is formed so as to gradually become thinner from the base end side (lower end side) to the front end side (upper end side). it can. For this reason, the front end side of the outer wall 33 can be bent more greatly by the pressure P acting on the pressure receiving recess 33, and the outer peripheral wall 33 can reliably block the pin outer peripheral gap 35 from above.

  On the other hand, after the forged product W is formed, the upper die 2 is raised, and then the forged product W is pushed up by the knockout pin 3 and discharged.

  In the third embodiment, other operation procedures and the like are the same as those in the first embodiment, and the same effects are achieved.

  Here, in the third embodiment, the thickness (thickness) A2 of the tip of the outer wall 33 in the pressure receiving recess 32 is set to 0.2 mm to 2.0 mm, preferably 0.5 mm to 1.0 mm. good. Furthermore, the height A3 of the outer wall 33, in other words, the depth A3 of the pressure receiving recess 32 is set to 0.2 mm to 2.0 mm, preferably 0.5 mm to 1.5 mm. Further, the radius of curvature of the inner peripheral surface of the pressure receiving recess 32 is set to R2 mm to R50 mm, preferably R3 mm to R10 mm. That is, by adjusting these values within the above specific range, the outer wall 33 can be appropriately bent during the forging process, and the pin outer peripheral gap 35 can be reliably closed.

  In addition, in this 3rd Embodiment, although the pressure receiving recessed part 32 of the knockout pin 3 is formed in the concave spherical shape, in this invention, the shape of the pressure receiving recessed part 32 is not restricted to a concave spherical shape. For example, the pressure receiving recess 32 is formed in a cylindrical recess, an inverted conical recess or an inverted frustoconical recess, further formed in a polygonal recess such as a quadrangular prism recess, an inverted square frustum recess, etc. You may make it form in a reverse polygon frustum-shaped recessed part. Further, the pressure receiving recess may be formed in a composite shape in which two or more shapes are combined.

  In the third embodiment, the outer wall 33 is formed on the entire circumference of the tip surface of the knockout pin 3. However, the present invention is not limited to this, and in the present invention, at least one of the outer peripheral edges of the pin tip surface. What is necessary is just to provide an outer wall in a part.

<Preferred means>
In the present invention, the following suitable means can be employed.

  [1] The forging die according to claim 9 or 10, wherein an outer side wall of the pressure receiving recess is formed on the entire circumference of the outer peripheral edge of the tip end surface of the knockout pin.

  [2] A forging die in which the outer side wall of the pressure receiving recess is formed thinner on the tip side than on the base side.

  [3] A forging die in which the inner peripheral surface of the pressure receiving recess is formed in a circular arc cross section.

  [4] A forging die in which a distance between an outer wall outer surface of the pressure receiving recess and an opening edge of the pin hole is set to 0.01 mm to 0.2 mm.

[5] A pressure receiving recess is formed on the tip surface of the knockout pin,
The outer wall of the pressure receiving recess is elastically deformed outward by the pressure of the forging material that plastically flows, and the gap between the outer peripheral edge of the knockout pin and the opening edge of the pin hole is caused by the elastically deformed outer wall. The forging method according to claim 11, wherein at least a part of the forging is closed.

  The forging die of the present invention can be used when a forged product made of aluminum or the like is manufactured by die forging.

1: Lower mold 11: Molding recess 12: Pin hole 13: Upper end (opening side end)
131: Inner peripheral surface 3: Knockout pin 31: Tip portion 32: Pressure receiving recess 33: Outer wall 35: Pin outer peripheral clearance P: Metal pressure W: Forged product θ1: Pin hole upper end portion inner peripheral surface gradient θ2: Pin tip portion Perimeter gradient

Claims (12)

A pair of molds for plastically deforming a forging material to form a forged product, and a knockout pin accommodated in a pin hole of one mold of the pair of molds so as to protrude, the knockout pin being A forging die that protrudes and protrudes the molded forged product from the one die,
While the tip of the knockout pin is formed so that the dimension in the outer diameter direction increases as it goes to the tip,
The opening side end of the pin hole is formed so that the dimension in the inner diameter direction becomes larger toward the opening side corresponding to the tip of the knockout pin,
A forging die, wherein the outer peripheral surface of the tip end portion of the knockout pin is brought into pressure contact with the inner peripheral surface of the opening side end portion of the pin hole by the pressure of the forging material that plastically flows. The tip outer peripheral surface of the knockout pin and the inner peripheral surface of the opening side end of the pin hole are formed in an inclined surface having a certain gradient,
2. The forging die according to claim 1, wherein gradients on the outer peripheral surface of the tip end portion of the knockout pin and the inner peripheral surface of the opening side end portion of the pin hole are both set to the same angle.   The forging die according to claim 2, wherein gradients of the outer peripheral surface of the tip end portion of the knockout pin and the inner peripheral surface of the opening side end portion of the pin hole are set to 2 ° to 45 °, respectively.   The tip outer peripheral surface of the knockout pin is in pressure contact with the inner peripheral surface of the opening side end of the pin hole by the pressure of the forging material that plastically flows. The forging die described in 1.   The forging die according to any one of claims 1 to 4, wherein a tip end portion of the knockout pin and an opening side end portion of the pin hole are formed in a truncated cone shape. A gap is formed between the outer peripheral surface of the tip portion of the knockout pin and the inner peripheral surface of the opening side end portion of the pin hole,
The forging die according to any one of claims 1 to 5, wherein the knockout pin is retracted by pressure of a forging material that plastically flows.   The state where the pressure of the plastic flowing forging material is not applied, the outer peripheral surface of the tip portion of the knockout pin is in contact with the inner peripheral surface of the opening side end portion of the pin hole. Forging mold. The one mold has a molding recess for molding a forged product,
The forging die according to any one of claims 1 to 7, wherein the knockout pin is disposed at the bottom of the molding recess.   The forging die according to any one of claims 1 to 8, wherein the forging die is configured by a die for hermetic or semi-hermetic forging.   The pressure receiving recess is formed at the tip surface of the knockout pin, and the outer wall of the pressure receiving recess is configured to be elastically deformable by the pressure of a forging material that plastically flows. Forging mold.   The forging die according to claim 10, wherein an inner peripheral surface of the pressure receiving recess is constituted by a concave spherical surface. The forging material is clamped by a pair of molds, and the forging material is plastically deformed to form a forged product. On the other hand, a knockout pin provided so as to protrude into the pin hole of one of the pair of molds. Is a forging method in which the formed forged product is projected from the one mold,
While forming the tip of the knockout pin so that the dimension in the outer diameter direction increases toward the tip side,
The opening side end portion of the pin hole is formed so that the dimension in the inner diameter direction becomes larger toward the opening side corresponding to the tip portion of the knockout pin,
A forging method, wherein the outer peripheral surface of the tip end portion of the knockout pin is brought into pressure contact with the inner peripheral surface of the opening side end portion of the pin hole by the pressure of the forging material that plastically flows.

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