JP2002282987A - Forging die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forging die capable of increasing the thickness of one side opposing two side wall parts when a forging product which is a nearly quadrangle ring shape in cross section is formed from a hollow cylindrical work. SOLUTION: The forging die 30 has a die 10 having upper part inner peripheral faces 10a and 10b which are symmetrical shapes relative to outer peripheral faces of a cylindrical part which is the nearly quadrangle ring shape in cross section of the forging product, and a punch 20 having an upper part axial part 21 which is the nearly quadrangle shape in cross section comprising two opposing faces 21a of nearly arc shapes in cross section and the other two opposing faces 12b of nearly linear shapes in cross section, at least in the upper end part. In this die, a clearance between the face 21a which is the nearly arc shape in cross section of the punch 20 and the upper part inner peripheral face 10a of the die is smaller than the thickness of a hollow cylindrical work W, and a clearance between the face 21b which is the nearly linear shape in cross section and the upper part inner peripheral face 10b of the die 10 is the same as or larger than the thickness of the hollow cylindrical work W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a forging die. More specifically, plastic deformation of a hollow cylindrical workpiece
The present invention relates to a forging die for producing a forged product having a cylindrical portion having a substantially quadrangular ring cross section and one of two opposing side walls having a thickness equal to or greater than the thickness of the original hollow cylindrical workpiece. .

[0002]

2. Description of the Related Art When a hollow cylindrical work is simply expanded concentrically, a hollow cylindrical work is arranged inside a die having an inner peripheral surface corresponding to the outer peripheral surface of the expanded work, and a taper is formed. A punch having a circular cross section having a portion can be inserted into a hollow shaft center of a hollow cylindrical work arranged inside a die to expand the pipe. In this case, as the outer peripheral surface of the punch expands concentrically, the thickness of the hollow cylindrical work entirely expands in the radial direction, and the inner peripheral surface and the outer peripheral surface of the work expand concentrically. Therefore, the diameter of the inner peripheral surface and the diameter of the outer peripheral surface are increased, but the thickness of the work after the expansion is reduced as a whole in the radial direction. In this case, the thickness between the inner peripheral surface and the outer peripheral surface in one cross section perpendicular to the axis of the expanded work is uniformly reduced.

[0003]

When a hollow cylindrical work is expanded in an irregular shape, for example, as shown in FIGS. 6A and 6B, the inner peripheral surface is expanded using a square punch having a square cross section. In this case, not only the wall thickness after the tube expansion is reduced, but also a portion that becomes a surplus is formed. That is, the work W
Is not uniformly reduced, but a difference occurs to the extent that the thickness is reduced. Here, (a) is the shape of the end face of the hollow cylindrical work W before the tube expansion as viewed from the axial direction, and (b) is the shape of the end face of the work W after the pipe expansion as viewed from the axial direction. The hollow cylindrical work W before pipe expansion shown in (a) is arranged on a die (not shown) having a cylindrical inner peripheral surface, and a punch P having a tapered surface and a rectangular cross section perpendicular to the axis is formed on the work. When the pipe is pushed and expanded into the hollow shaft center portion H of W, the end face of the workpiece W after pipe expansion has a shape as shown in FIG. That is, a workpiece W having an inner peripheral surface having a substantially quadrangular cross section and an outer peripheral surface having a circular cross section is formed. In this case, the thickness at B of the work W after the expansion in (B) is smaller than the thickness at A of the work W before the expansion in (A). That is, the thickness of the work W after the expansion is generally thinner than the thickness of the work W before the expansion.

However, for example, when a portion indicated by V in (b) is removed as a surplus portion in a later step, it is not necessary to have a thickness as large as V has. That is, the thickness of this portion may be thin. Rather, it is preferable to reduce the thickness of the portion indicated by V and increase the thickness of the portion indicated by U. If the portion indicated by U is removed and the portion indicated by U is required, the thickness of the portion indicated by U is preferably thick. Therefore, in such a case, it is necessary to reduce the thickness of the two opposing side walls indicated by V and increase the thickness of the other opposing two side walls indicated by U.

An object of the present invention is to provide a forging metal capable of increasing the thickness of one of two opposite side walls when forming a forged product having a substantially quadrangular cross section from a hollow cylindrical work. Is to provide a type.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors plastically deformed a hollow cylindrical workpiece and found that the thickness of two opposing side walls having a substantially quadrangular ring shape in cross section was reduced. A forging die for producing a forged product having a cylindrical portion having a thickness equal to or greater than the thickness of a hollow cylindrical work, wherein at least an upper end portion has an outer peripheral surface of the cylindrical portion of the forged product and a target for molding. A die having an upper inner peripheral surface, a shaft hole of the hollow cylindrical work at a lower end portion, and a cutting shaft opposed to a lower shaft portion and an upper end portion of a die object;
An upper shaft portion having a substantially quadrangular cross section composed of two substantially arc-shaped cross-sectional surfaces and another two substantially straight cross-sectional surfaces facing each other has a lower shaft portion and a tapered surface connecting the upper shaft portion at an intermediate portion. A clearance between the cross-section substantially arc-shaped surface of the punch and the upper inner peripheral surface of the die is smaller than the thickness of the hollow cylindrical work, and the cross-section substantially linear surface of the punch and the A forging die has been invented, wherein the clearance between the die and the upper inner peripheral surface is equal to or greater than the thickness of the hollow cylindrical workpiece.

That is, a forged product manufactured by plastically deforming a hollow cylindrical workpiece in the forging die of the present invention has a substantially quadrangular ring shape in cross section, and one of two opposing side walls has a wall thickness of the hollow cylindrical workpiece. Has a cylindrical portion that is equal to or greater than the thickness of the cylindrical member.

[0008] The cylindrical portion can be formed by the forging die of the present invention as follows. First, the clearance between the substantially arc-shaped cross section of the upper shaft of the punch and the upper inner peripheral surface of the die is made smaller than the thickness of the hollow cylindrical work, and the hollow cylindrical work is crushed. The hollow cylindrical workpiece is extruded from the space between the surface and the upper inner peripheral surface of the die. On the other hand, the clearance between the substantially linear cross section of the punch and the upper inner peripheral surface of the die is equal to or greater than the thickness of the hollow cylindrical work, and the extruded hollow cylindrical work is cut into the cross section of the punch. It should be possible to move to the space between the linear surface and the upper inner peripheral surface of the die. As a result, the meat of the original hollow cylindrical work can be moved to this space, and the meat in this portion can be increased.

In this way, the hollow cylindrical work is plastically deformed to form a cylindrical part having a substantially quadrangular ring cross section and one of two opposing side walls having a thickness equal to or greater than the thickness of the hollow cylindrical work. Can be manufactured.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A forging die according to the present invention is obtained by plastically deforming a hollow cylindrical work, and has a substantially quadrangular ring-shaped cross section and one of two opposing side walls having a wall thickness of the hollow cylindrical work. A forging die for producing a forged product having a cylindrical portion having a thickness equal to or greater than a thickness, wherein the die has at least an upper end portion having an outer peripheral surface of a cylindrical portion of the forged product and an upper inner peripheral surface of a mold object. The lower end portion has a shaft hole of a hollow cylindrical workpiece, a lower shaft portion to be shaped, and the upper end portion has two opposing substantially arc-shaped cross-sectional surfaces and two other opposing substantially linear surfaces. A punch having a lower shaft portion and a tapered surface connecting the upper shaft portion to an upper shaft portion and an intermediate portion having a substantially quadrangular cross section, and having a substantially arc-shaped cross section of the punch and the upper inner peripheral surface of a die. The clearance is smaller than the thickness of the hollow cylindrical workpiece, and the cross-section of the punch is substantially straight and the top of the die is closed. Wherein the clearance between the inner peripheral surface is a hollow cylindrical wall thickness of the workpiece and the same or more.

An embodiment of the present invention will be described below.

The hollow cylindrical workpiece plastically deformed by the forging die of the present invention is a hollow cylindrical workpiece having the same outer diameter and inner diameter from the upper end to the lower end, and the outer diameter is reduced in the middle of the axial direction. A hollow cylindrical work can be used. In this case, the hollow cylindrical workpiece whose diameter has been reduced may be a hollow cylindrical workpiece whose diameter is reduced from the middle to the lower end, or a hollow cylindrical workpiece whose diameter is reduced only at an intermediate portion.

The forged product manufactured from the hollow cylindrical workpiece has a cylindrical portion having a substantially quadrangular ring shape in cross section and having two opposite side walls having a thickness equal to or greater than the thickness of the hollow cylindrical workpiece. It is a forged product having. Therefore, in this forged product, the portion other than the cylindrical portion, which is expanded and has a substantially quadrangular ring shape in cross section and the thickness of one of two opposing side walls is equal to or greater than the thickness of the hollow cylindrical work, Alternatively, a portion having the initial hollow cylindrical shape may be left without being expanded.

The die has an outer peripheral surface of a cylindrical portion of a forged product and an upper inner peripheral surface of a die object at least at an upper end portion. By forming the inner peripheral surface of the upper end of the die, that is, the upper inner peripheral surface, as the outer peripheral surface of the cylindrical portion of the forged product, the hollow cylindrical work is plastically deformed at least at the upper end of the die. The outer peripheral surface of the part can be formed.

Since the shape of the cylindrical portion of the forged product is a substantially quadrangular ring shape in cross section, the cylindrical portion and the upper inner peripheral surface of the die to be molded are also substantially quadrangular in cross section. In addition, with respect to the substantially quadrangular cross-section of the upper inner peripheral surface, the surface corresponding to the substantially arc-shaped cross-section of the punch is similarly formed into a substantially arc-shaped cross-section in accordance with the shape of the upper shaft portion of the punch described later. The surface corresponding to the substantially linear cross-section surface can be made a substantially linear cross-sectional surface. In this way, the outer peripheral surface of the punch and the inner peripheral surface of the die are both formed into a substantially arcuate cross-sectional surface by crushing and extruding the meat of the hollow cylindrical work from both sides. Can be easily moved.

In this case, when the outer diameter and the inner diameter of the hollow cylindrical workpiece have the same diameter from the upper end to the lower end, the inner peripheral surface of the die has the same axis perpendicular to the upper inner peripheral surface from the upper end to the lower end of the die. The cross-sectional shape, that is, a substantially quadrangular cross-section can be used.

When the hollow cylindrical workpiece has a tapered surface in the middle due to a reduction in diameter in the middle, the upper end of the inner peripheral surface of the die and the outer peripheral surface of the cylindrical portion of the forged product and the upper part of the die object The inner peripheral surface may be formed, and the lower end portion may be formed as the outer peripheral surface of the initial hollow cylindrical work and the lower inner peripheral surface of the mold object, and a space between them may be a tapered surface corresponding to the tapered surface of the hollow cylindrical work.

The punch of the forging die of the present invention has a lower shaft at the lower end, an upper shaft at the upper end, and a tapered surface connecting the lower shaft and the upper shaft at the middle. The lower shaft located at the lower end of the punch is the object of the shaft hole of the hollow cylindrical work.
Accordingly, the lower shaft portion has a cylindrical shape, and the diameter of the lower shaft portion is substantially the same as the diameter of the shaft hole so that the lower shaft portion can be inserted into the shaft hole to fill the space. The axial length of the lower shaft portion is preferably substantially the same as or longer than the axial length of the shaft hole. When the space of the shaft hole is not filled by the lower shaft portion of the punch in this way, when the punch is pressed against the hollow cylindrical work to cause the flesh of the hollow cylindrical work to plastically flow,
The meat of the hollow cylindrical work moves into the space of the shaft hole. Therefore, by previously filling the space of the shaft hole of the hollow cylindrical work with the lower shaft portion, it is possible to suppress the movement of the wall of the hollow cylindrical work to the shaft hole.

The upper shaft located at the upper end of the punch has a substantially quadrangular cross-section, and the outer peripheral surface of the upper shaft has two substantially arc-shaped cross-sections opposed to each other and two other opposed arc-shaped surfaces. It has a substantially linear cross section. In this case, the substantially arc-shaped cross-section surface of the punch is a substantially arc-shaped cross-section surface projecting outward. And the clearance between the cross section of the punch and the inner peripheral surface of the die is smaller than the thickness of the hollow cylindrical work.
The clearance between the substantially linear cross section of the punch and the upper inner peripheral surface of the die is equal to or greater than the thickness of the hollow cylindrical workpiece.

By setting the clearance between the substantially arcuate cross-sectional surface of the punch and the upper inner peripheral surface of the die smaller than the initial thickness of the hollow cylindrical workpiece, the substantially arcuate cross-sectional surface of the punch is obtained. The hollow cylindrical workpiece sandwiched between the die and the upper inner peripheral surface of the die is crushed and plastically extruded. In this case, since the outer peripheral surface of the punch on the side where the clearance is set to be smaller than the initial thickness of the hollow cylindrical workpiece is a substantially arc-shaped cross-section that protrudes outward, it was crushed and extruded. The meat is extruded from the center of the substantially arc-shaped cross section to the end.

Since the clearance between the substantially linear cross-section surface of the punch and the upper inner peripheral surface of the die is equal to or greater than the thickness of the hollow cylindrical work, the extruded meat is formed with the substantially linear cross-section surface of the punch. It will move to the space between the upper inner peripheral surface of the die. Even if the clearance is the same as the initial thickness of the hollow cylindrical work, the space in this portion is increased by expanding the hollow cylindrical work as a whole. Therefore, the flesh crushed and extruded between the substantially arc-shaped cross section of the punch and the upper inner peripheral surface of the die moves to the space between the substantially linear cross section of the punch and the upper inner peripheral surface of the die. become. Therefore, in this space, the thickness of the forged product can be increased.

Then, a cylindrical portion of a forged product is formed by the upper shaft portion of the punch and at least the upper inner peripheral surface of the die. The cylindrical portion has a substantially quadrangular ring shape in cross section, and is formed such that the thickness of one of two opposing side walls is equal to or greater than the thickness of the hollow cylindrical workpiece.

The tubular part of the forged product can be formed up to the point where the upper shaft part of the punch advances in the axial direction. Therefore, the outer diameter and the inner diameter of the hollow cylindrical work maintain the same diameter from the upper end to the lower end, and the inner peripheral surface of the die has the same axial perpendicular cross-sectional shape as the upper inner peripheral surface from the upper end to the lower end of the die, that is, approximately four sides in cross section. In the case of the shape, the upper shaft portion of the punch can be advanced to near the lower end of the die. Therefore, the cylindrical portion can be formed to the vicinity of the lower end of the hollow cylindrical work.

The hollow cylindrical workpiece has a tapered surface in the middle part with a reduced diameter in the middle, and the inner peripheral surface of the die has an upper end whose outer peripheral surface of the cylindrical portion of the forged product and the upper inner peripheral surface of the die object. If the lower end is the outer peripheral surface of the original hollow cylindrical work and the lower inner peripheral surface of the mold object, and the space between them is the tapered surface corresponding to the tapered surface of the hollow cylindrical work, the upper shaft of the punch should be To the vicinity of the tapered surface.
Therefore, the hollow cylindrical work can be formed into a cylindrical portion up to the vicinity of the tapered surface.

The punch has a tapered surface in the middle portion connecting the lower shaft portion and the upper shaft portion with a curved surface. In the forging die of the present invention, the lower shaft portion is inserted into the shaft hole of the hollow cylindrical work, and is formed by plastically deforming the work mainly with the outer peripheral surface of the upper shaft portion and the upper inner peripheral surface of the die. A tapered surface is provided between the lower shaft portion and the upper shaft portion so that the meat of the hollow cylindrical work flows as perpendicularly as possible to the direction in which the punch advances. By forming a tapered surface between the upper shaft portion and the lower shaft portion as described above, the upper shaft portion can easily advance in the axial direction, and the molding pressure can be reduced.

As described above, according to the forging die of the present invention, the cylindrical portion having a substantially quadrangular ring shape in cross section and having two opposing side walls having a thickness equal to or greater than the thickness of the hollow cylindrical workpiece. Can be made.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a forging die according to the present invention will be described below with reference to the drawings.

(Example 1) FIG. 1 shows a forging die of Example 1.
And FIG. FIG. 1 is a plan view of a forging die 30 in which a hollow cylindrical work W is disposed. The left half of FIG. 1 shows a die 10 and a hollow cylindrical work W before expansion.
The right half of the die is a die 10, a punch 20, and a work W after expansion.
FIG.

FIG. 2 is a front sectional view of the forging die 30. The left half of FIG. 2 shows a state where only the lower shaft portion 20c of the punch 20 is inserted into the shaft hole of the work W, and the right half of FIG. 2 shows a state where the punch 20 is pushed into the work W and the work W is expanded.

The work W used in this embodiment is a hollow cylindrical work having an outer diameter and an inner diameter whose diameter remains the same from the upper end to the lower end. That is, it is a hollow cylindrical work whose diameter has not been increased or reduced in the axial direction.

In this embodiment, the outer peripheral surface of the die 10 has a circular side surface in cross section. On the other hand, die 10
Has two opposing substantially arc-shaped cross-sectional surfaces 10a having a substantially circular cross-sectional shape and two opposing substantially linear cross-sectional surfaces 10b having a substantially linear cross-sectional shape.
The die 10 of this embodiment has the same cross section perpendicular to the axis from the upper end to the lower end, like the work. Further, the die 10 of this embodiment has a shape having no bottom surface at both the upper end and the lower end. In this embodiment, the dice 10 are placed on the fixed plate 40. The fixing plate 40 is provided with a hole where the shaft hole of the work W is located when the work W is disposed.

In the present embodiment, the work W is disposed on the fixed plate 40, but a bottom surface may be provided at the lower end of the die 10 instead of the fixed plate 40. In this case, a hole can be provided on the bottom surface where the shaft hole of the work W is located when the work W is disposed.

The punch 20 has an upper shaft portion 21 at an upper end, a lower shaft portion 23 at a lower end portion, and a tapered surface 22 at an intermediate portion connecting the upper shaft portion 21 and the lower shaft portion 23 with a curved surface.

The lower shaft portion 23 at the lower end has a shape corresponding to the shape of the shaft hole of the hollow cylindrical work W. That is, the lower shaft portion 2
The length 3 has a length slightly exceeding the length of the shaft hole of the work W. The cross-sectional shape is circular, and the size of the diameter is such that it can be inserted into the shaft hole of the work W with almost no gap. Therefore, when expanding the work W, first, the lower shaft portion 23 of the punch 20 can be inserted into the shaft hole of the work W, and the lower shaft portion 23 can be penetrated from one end to the other end of the shaft hole. As described above, since the shaft hole of the work W is previously penetrated from one end to the other end by the lower shaft portion 23 of the punch 20, even when the work W is plastically flowed through the upper shaft portion 21 of the punch 20, the work W W meat is work W
Can also be prevented from flowing into the shaft hole.

In this embodiment, the upper shaft portion 21 at the upper end of the punch 20 has two opposing substantially arc-shaped cross-sections 21a having a substantially arc-shaped cross section and two opposing substantially arc-shaped surfaces 21a having a substantially straight cross-section. It has a substantially straight surface 21b in cross section. However, the clearance between the substantially arc-shaped surface 21a of the cross section of the upper shaft portion 21 of the punch 20 and the substantially arc-shaped surface 10b of the die 10 is
The thickness is set to be smaller than the thickness of the work W before expansion.
The cross-section of the upper shaft portion 21 is substantially linear and the die 1
The clearance with the substantially straight cross-section surface 10b of 0 is set to be larger than the thickness of the work W before expansion.

The tapered surface 22 between the upper shaft portion 21 and the lower shaft portion 23 forms an upper shaft so that the upper shaft portion 21 can be pushed into the work W following the lower shaft portion 23 inserted into the shaft hole. The portion 21 and the lower shaft portion 23 are smoothly connected by a curved surface.

The forging die of Embodiment 1 thus configured can be used as follows.

As shown in the left half of FIG. 1, a hollow cylindrical work W is disposed inside the die 10 placed on the fixed plate 40. At this time, the axial hole of the hollow cylindrical work W is made to overlap the hole provided in the fixed plate 40.

Next, the lower shaft portion 23 of the punch 20 is
Into the shaft hole. Since the length of the lower shaft portion 23 is slightly longer than the length of the shaft hole of the work W, the lower shaft portion 23 is inserted into the shaft hole of the work W as shown in the left half of FIG. The tip of the shaft portion 23 slightly protrudes from the lower end surface of the work W.

Next, the work 20 is pressed by pressing the punch 20 downward.
Press Upper shaft portion 21 and lower shaft portion 23 of punch 20
Is formed on the tapered surface 22 so that the punch 2
In FIG. 2, the taper surface of the punch 20 reaches near the lower end surface of the work W as shown in the right half of FIG.

At this time, the upper shaft portion 21 of the punch 20 is
Has a substantially arc-shaped cross section 21a and a substantially straight cross section 21b as shown in the right half of FIG. The cross-section substantially arc-shaped surface 21a of the upper shaft portion 21 and the cross-section substantially arc-shaped surface 10a of the die 10
Is smaller than the initial thickness of the work W. The clearance between the substantially straight surface 21b of the cross section of the upper shaft portion 21 and the substantially straight surface 10b of the die 10 is smaller than the initial thickness of the work W.

Accordingly, the cross-section of the punch 20 has a substantially arc-shaped surface 21a.
The work W sandwiched between the die 10 and the substantially arc-shaped surface 10a of the die 10 is crushed and extruded.

FIG. 3 shows the movement of the meat of the work W in the upper half of the right half of FIG. As indicated by the arrows in the figure,
The meat of the work W sandwiched between the substantially arc-shaped surface 21a of the punch 20 and the substantially arc-shaped surface 10a of the die 10 is extruded from the space between the two substantially arc-shaped surfaces 21a, 10a. The cross-section substantially linear surface 21b of the punch 20 having a large clearance and the cross-section substantially linear surface 10b of the die 10
Will move to the space between. Therefore, in this portion, the thickness of the work W becomes thicker than the original thickness. That is, the meat in this portion increases.

(Embodiment 2) FIGS. 4 and 5 show a forging die 70 of Embodiment 2. FIG. FIG. 4 shows a hollow cylindrical work W inside.
FIG. 4 is a plan view of a forging die 70 provided with. The left half of FIG. 4 shows the die 50 and the work W before expansion, and the right half of FIG. 4 shows the state of the die 50, the punch 60, and the work W after expansion. FIG. 5 is a front sectional view of the forging die 70. The left half of FIG. 5 shows a state where only the lower shaft portion 63 of the punch 60 is inserted into the shaft hole of the work W, and the right half of FIG. 5 shows a state where the work is expanded by pushing the punch 60 into the work W. . The same reference numerals as in Example 1 were used for the work.

The work W used in this embodiment is a hollow cylindrical work W. However, in this embodiment, the outer peripheral surface of the hollow cylindrical work W is reduced in the middle. That is, as shown in the left half of FIG. 5, the work W is a hollow cylindrical work including an upper cylinder, a lower cylinder having an outer diameter smaller than that of the upper cylinder, and an intermediate portion having a tapered surface located therebetween. Accordingly, the outer peripheral surface of the work W is composed of the side surface of the upper cylinder, that is, the upper outer peripheral surface W1, the side surface of the lower cylinder, that is, the lower outer peripheral surface W3, and the tapered surface W2 connecting them. However, the diameter of the shaft hole of the work W is the same from the upper end to the lower end.

In this embodiment, as in the first embodiment, the outer peripheral surface of the die 50 has an outer peripheral surface having a circular cross section.
On the other hand, the inner peripheral surface of the die 50 has an inner peripheral surface at the upper end, that is, an upper inner peripheral surface 51, a lower inner peripheral surface, a lower inner peripheral surface 53, an upper inner peripheral surface 51, and a lower inner peripheral surface 53. And a connecting tapered surface 52. The upper inner peripheral surface 51 has two opposing substantially arc-shaped surfaces 51a having a substantially arc-shaped cross section and two substantially linear surfaces 51b having a substantially straight cross-section. The inner peripheral surface at the lower end, that is, the lower inner peripheral surface 53 is a target of the lower outer peripheral surface W3 of the work W. And dice 1
0 is the tapered surface 52 of the workpiece W.
And an inclined surface that overlaps with

The punch 60 has an upper shaft 61 at an upper end, a lower shaft 63 at a lower end, and a tapered surface 62 at an intermediate portion connecting the upper shaft 61 and the lower shaft 63 with a curved surface.

The lower shaft portion 63 at the lower end has a shape corresponding to the shape of the shaft hole of the hollow cylindrical work W. That is, the lower shaft portion 6
The length 3 has a length slightly exceeding the length of the shaft hole of the work W. The cross-sectional shape is circular, and the size of the diameter is approximately the same size that can be inserted into the shaft hole of the work W without any gap.

Therefore, when expanding the work W, first, the lower shaft portion 63 of the punch 60 is inserted into the shaft hole of the work W, and the lower shaft portion 63 can be penetrated from one end to the other end of the shaft hole. . Thus, the lower shaft portion 63 of the punch 60
Thus, even when the flesh of the work W is plastically flowed by the upper shaft portion 61 of the punch 60, the flesh of the work W is It can also be prevented from flowing into the shaft hole.

Also in this embodiment, the upper shaft portion 61 at the upper end of the punch 60 has two opposing substantially arc-shaped surfaces 61a having a substantially arc-shaped cross section and two opposing substantially arc-shaped surfaces 61a having a substantially linear cross section. It has a substantially straight surface 61b in cross section. The clearance between the substantially arc-shaped surface 61a of the upper shaft 61 of the punch 60 and the substantially arc-shaped surface 51b of the upper end of the die 50 is set to be smaller than the thickness of the workpiece W before expanding. The clearance between the substantially straight surface 61b of the cross section of the upper shaft 61 and the substantially straight surface 51b of the cross section of the upper end of the die 50 is set to be larger than the thickness of the workpiece W before the expansion.

The tapered surface 62 between the upper shaft portion 61 and the lower shaft portion 63 is formed so that the upper shaft portion 61 can be pushed into the workpiece W following the lower shaft portion 63 inserted into the shaft hole. The portion 61 and the lower shaft portion 63 are smoothly connected by a curved surface.

The thus-configured forging die 70 of Embodiment 2 can be used as follows.

As shown in the left half of FIG. 4 and the left half of FIG. 5, a hollow cylindrical work W is disposed inside the die 50. At this time, since the lower outer peripheral surface W3 of the lower cylinder of the hollow cylindrical work W is formed with the lower inner peripheral surface 53 of the die 50, the lower cylindrical portion of the work W is formed by the lower inner peripheral surface 53 of the die 50. It can be inserted into a cylindrical space.

Next, the lower shaft portion 63 of the punch 60 is
Into the shaft hole. Since the length of the lower shaft portion 63 is formed slightly longer than the length of the shaft hole of the work W, the lower shaft portion 63 is inserted into the shaft hole of the work W as shown in the left half of FIG. The tip of the shaft portion 63 slightly protrudes from the lower end surface of the work W.

Next, the work piece W is pressed by pressing the punch 60 downward.
Press Upper shaft portion 61 and lower shaft portion 63 of punch 60
Are formed on the tapered surface 62 so that the punch 6
In FIG. 5, the taper surface 62 of the punch 60 reaches close to the taper surface W2 of the work W as shown in the right half of FIG.

At this time, the upper shaft 61 of the punch 60 is
Has a substantially arc-shaped cross section 61a and a substantially straight cross section 61b. The clearance between the substantially arc-shaped surface 61a of the upper shaft portion 61 and the substantially arc-shaped surface 51a of the upper outer peripheral surface 51 of the die 50 is smaller than the thickness of the work W at the beginning. The upper shaft 61 of the punch 60
The cross-section substantially linear surface 61b and the upper outer peripheral surface 51 of the die 50
Of the workpiece W is smaller than the initial thickness of the workpiece W.

Therefore, the cross section of the punch 60 is substantially arc-shaped.
The meat of the work W sandwiched between the work W and the substantially arc-shaped surface 11a of the die 50 is crushed and extruded. The situation at this time is the same as that shown in FIG.

In this embodiment, the upper cylindrical portion of the work W can be formed into a cylindrical portion of a forged product. The lower cylindrical portion of the work W is left as it is without being formed.

Thus, Embodiments 1 and 2 of the present invention
In the above, a thickness greater than the initial thickness of the work can be formed by plastic flow.

The forging die of the present invention is not limited to the first and second embodiments. Deformation is possible within the scope described in the claims.

[0061]

The hollow cylindrical work is plastically deformed by the forging die of the present invention, and the thickness of one of the two opposing side walls having a substantially quadrangular ring shape in cross section is the thickness of the hollow cylindrical work. Forgings having a tubular portion that is the same as or greater than can be made.

[Brief description of the drawings]

FIG. 1 is a plan view of a forging die according to a first embodiment.

FIG. 2 is a front sectional view of a forging die according to the first embodiment.

FIG. 3 is a diagram showing a flow of meat when expanding a hollow cylindrical workpiece in the first embodiment.

FIG. 4 is a plan view of a forging die according to a second embodiment.

FIG. 5 is a front sectional view of a forging die according to a second embodiment.

FIG. 6 is a view showing a state of a conventional pipe expansion.

[Explanation of symbols]

 W: hollow cylindrical work W1: upper outer peripheral surface of hollow cylindrical work in Example 2 W2: tapered surface of hollow cylindrical work in Example 2 W3: lower outer peripheral surface of hollow cylindrical work in Example 2 10: die 10a: die Substantially arcuate surface 10b: Substantially linear surface of die 20: Punch 21: Upper shaft portion of punch 21a: Substantially circular surface of punch 21b: Substantially linear surface of punch 22: Tapered surface of punch 23: Lower shaft portion of punch 30: Forging die 40: Fixing plate 50: Die 51: Upper inner peripheral surface of die 51a: Cross section of upper inner peripheral surface of die substantially arc-shaped surface 51b: Cross section of upper inner peripheral surface of die Substantially straight surface 52: Die taper surface 53: Die lower inner peripheral surface 60: Punch 61: Punch upper shaft portion 61a: Punch cross-section substantially arc-shaped surface 61b: Punch Menryaku straight surface 62: the punch of the tapered surface 63: lower punch shaft portion 70: forging die

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Nemoto 2-20-1 Yasushidori, Nishi-ku, Nagoya-shi, Aichi Prefecture Meitec Co., Ltd.・ Easy F-term (reference) 4E087 AA10 EC11

Claims (3)

[Claims] 1. A hollow cylindrical workpiece having a substantially quadrangular ring shape and a thickness of one of two opposing side walls being equal to or greater than the thickness of the hollow cylindrical workpiece by plastically deforming the hollow cylindrical workpiece. A die having at least an upper end portion having an outer peripheral surface of the cylindrical portion of the forged product and an upper inner peripheral surface of a die object; and a lower end portion having the hollow. An upper shaft having a substantially quadrilateral cross-section comprising two opposing substantially arc-shaped cross-sections and two other opposing substantially linear cross-sections at the lower shaft portion and the upper end portion of the shaft hole of the cylindrical work, and the upper end portion. A punch having a tapered surface connecting the lower shaft portion and the upper shaft portion to the portion and the intermediate portion, and a clearance between the substantially arc-shaped cross-sectional surface of the punch and the upper inner peripheral surface of the die is provided. Smaller than the thickness of the hollow cylindrical workpiece, the cross-section of the punch being substantially linear and the upper surface of the die being A forging die, wherein a clearance with a peripheral surface is equal to or greater than a thickness of the hollow cylindrical work. 2. The forging die according to claim 1, wherein the die has an inner peripheral surface having a cross section perpendicular to the axis, which is the same as the upper inner peripheral surface, from the upper end to the lower end in the axial direction. 3. The forging metal according to claim 1, wherein in the punch, the axial length of the lower shaft portion is substantially the same as or longer than the axial length of the shaft hole of the hollow cylindrical workpiece. Type.