JP2836381B2 - Reverse ironing device and reverse ironing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ironing method in which a cylindrical portion of a material forming a cylindrical container is reversely ironed in a direction opposite to the conventional ironing method, that is, from the opening side to the bottom side of the material. And a reverse ironing device.

[0002]

2. Description of the Related Art The present applicant has previously devised the above-mentioned reverse ironing method, and has also devised the following reverse ironing device for implementing the reverse ironing method. This is a reverse ironing device described in Japanese Utility Model Publication No. 59-29770 of the present applicant, and will be described below with reference to FIG. In the figure, the left half shows the state immediately after the start of the reverse ironing, and the right half shows the state immediately after the end of the reverse ironing.

[0003] This reverse ironing device includes a pushing punch 200 and a die 202. The pushing punch 200 is moved up and down by a driving device (not shown), and its distal end surface is flat. On the other hand, the die 202 has a die hole 2 which is a stepped through hole into which the pressing punch 200 is inserted.
04 and is fixed to the base 208.

[0004] The die hole 204 is provided with an upper small-diameter hole 210.
And a large-diameter hole 212 on the lower side. The small hole 2
An ironing punch 216 with a flange is slidably fitted to 10 via a sleeve 218 with a flange. Cushion pin 2 below ironing punch 216
Numeral 20 is arranged to be vertically movable, and always urges the ironing punch 216 and the sleeve 218 toward the upper end position (the position shown in the left half of the figure). That is, the flange portion 222 of the sleeve 218 is
It is urged toward the position where it comes into contact with the shoulder between 10 and the large diameter hole 212. The distal end surface of the sleeve 218 is located substantially at the center of the ironing punch 216 in the axial direction,
The material W is located at an appropriate position in relation to the final height dimension. A portion of the ironing punch 216 that is not covered with the sleeve 218 is covered with the material W, and the portion of the ironing punch 216 is placed in the small-diameter hole 2.
In cooperation with the ironing surface 223 which is a cylindrical surface of No. 10, the material W is squeezed from the opening side to the bottom side thereof,
The opening end face of the material W is formed on the tip end face of the sleeve 218.

[0005] The ironing punch 216 also has a cushion pin 22.
0 is also hollow, and the eject pin 2
24 are slidably fitted. The position of the eject pin 224 shown in the left half of the drawing with respect to the ironing punch 216 is regarded as a non-operating position. From this state, the eject pin 224 is relatively moved upward with respect to the ironing punch 216, so that the tip of the ironing punch 216. The material W after the reverse ironing placed on the part is paid out from the ironing punch 216.

Next, the operation of the reverse ironing device will be described.
In addition, when reverse ironing is performed on the material W, roughly explaining, two basic steps, namely, an ironing punch 2 by a grip finger of a feeder (not shown).
The material W positioned at a predetermined position directly above the die 16 is pressed by the punch 220 into the die hole 20 together with the punch 216.
4, the entire cylindrical portion of the raw material W is squeezed, and the first basic process is performed.
And the like, and the second basic process of paying out the material W from the ironing punch 216 is sequentially performed. A set of these basic processes is simply referred to as “machining”, whereas the first basic process is performed. Is called "reverse ironing".

[0007] Before the start of machining, the pressing punch 200
Are retracted upward from the position shown in the left half of the figure. In this state, the material W is gripped by the grip fingers and positioned just above the tip end surface of the ironing punch 216. Thereafter, the processing is started, the pushing punch 200 is lowered from the retracted position (not shown) and engages with the outer surface of the bottom of the material W, and the material W is separated from the grip finger by further lowering the pushing punch 200, and is ironed. It is put on the tip of the punch 216. Thereafter, the pushing punch 200 descends and engages with the tip of the ironing punch 216 via the bottom of the material W. Thereafter, as the pressing punch 200 descends, the material W, the ironing punch 216, the sleeve 218, and the eject pin 224 and the cushion pin 220 are integrally lowered against the lifting force of the cushion pin 220 in the direction of raising the ironing punch 216.

[0008] The material W is made of an iron punch 2
16 and the ironing surface 223, and are lowered while being ironed together.
When one reverse ironing is completed when the material W comes into contact with the upper surface of the ironing surface 08, the open end of the material W coincides with the lower end of the parallel portion of the ironing surface 223 or at a position lower than the lower end. The end on the bottom side of the parallel portion of the cylindrical portion of the material W (see FIG. 15 which is an enlarged view of the portion A in FIG. 14; indicated by “P _W ” in FIG. 14) is the parallel portion of the ironing surface 223. 16 (which is an enlarged view of a portion B in FIG. 14).
reference. (Indicated by “P _D ” in the same figure) or when it reaches a position below it,
As shown in the right half of FIG. 14, the lower end surface of the ironing punch 216 is brought into contact with the upper surface of the base 208 to complete one reverse ironing.

In this reverse ironing, the inner surface of the raw material W is restrained by the outer peripheral surface of the ironing punch 216, while the outer surface is restrained by the distal end surface of the pushing punch 200, the ironing surface 223, and the distal end surface of the sleeve 218, respectively. The entire inner and outer surfaces of the material W are almost completely sealed by the outer peripheral surface of the ironing punch 216 and the like.
Is formed so as to accurately match the target shape. Of the material of the cylindrical part of material W, the surplus meat due to ironing is material W
Flows from the opening side to the bottom side, and is filled in the space between the outer surface of the bottom part and the tip end face of the pushing punch 200.

When one reverse ironing operation is completed as described above, the pushing punch 200 is raised this time, and accordingly, the material W is raised integrally with the ironing punch 216 and the like by the lifting force of the cushion pin 220. Then, the punching iron 216 reaches the upper end position, while the pushing punch 200 is further raised and reaches the retreat position. At this time, the ascending of the eject pin 224 is started, and when the eject pin 224 protrudes from the front end surface of the ironing punch 216, the material W is discharged from the ironing punch 216. Thereafter, the material W is gripped by the grip fingers and sent to the next process. This completes one process.

According to the conventional ironing method, FIG.
As shown in the figure, the cylindrical portion of the material W is squeezed from the bottom side toward the opening side. At this time, compressive stress is applied to the cylindrical portion in the circumferential direction and tensile force is applied in the axial direction. Each stress is generated. On the other hand, according to the reverse ironing method, as shown in FIG. 18, the cylindrical portion of the material W is squeezed from the opening side to the bottom side thereof,
At this time, compressive stress is generated in the cylindrical portion in both the circumferential direction and the axial direction. Thus, according to the reverse method,
There is no room for tensile stress to be generated in the cylindrical portion of the material W, and compressive stress always remains.

Therefore, when a conventional ironing method is applied to a material comprising an unstable austenitic phase such as austenitic stainless steel or a high-strength material such as high-strength steel, the cylindrical portion of the material ( In particular, a tensile stress remains at the tip of the material, and when left for a short time (several minutes to several days), the cylindrical portion of the material is axially torn from its open end without external force. An example of a material in which this occurs is shown in FIG. 19), and when a conventional ironing method is applied to a material made of a general material such as carbon steel, a cylindrical portion of the material is formed. (Especially at the tip of the material), the tensile stress remains, and the material cylindrical portion becomes brittle due to work hardening. As soon as the processing stress is removed, the material cylindrical portion is axially moved from its open end. Tear So-called vertical cracking is easy to occur, but if the reverse ironing method is adopted instead of the conventional ironing method, the material can be made of stainless steel with an unstable austenite phase, high-strength material, or general material Since the compressive stress always remains in the cylindrical portion (at least the tip portion) of the material, cracking of the material after ironing is reliably prevented.

[0013]

As is clear from the above description, the problem of cracking of the material after ironing can be surely solved by adopting the reverse ironing method.
It has been found that when performing the reverse ironing using the conventional reverse ironing apparatus, there are the following specific problems.

That is, a portion connecting the cylindrical portion and the bottom portion of the outer surface of the raw material W (hereinafter referred to as an outer peripheral edge portion; see FIG. 15).
In the case where the space between the inner surface of the material W and the leading end surface of the pushing punch 200 is relatively small, the surface of the inner surface of the material W connecting the cylindrical portion and the bottom portion (hereinafter, simply referred to as an inner peripheral corner portion; see FIG. 15). So-called sink marks are unlikely to occur. On the other hand, for example, FIG.
As shown in FIG. 5, when the space between the outer peripheral edge portion and the distal end face of the press-in punch 200 is relatively large, there is an advantage that extra space generated by ironing is surely filled in the space, On the other hand, a so-called sink occurs on the surface of the inner peripheral corner, and when the sink grows, for example, as shown in FIG. However, it has been found that there is a problem that defects to be referred to easily occur.

If the space between the outer peripheral edge of the material W and the leading end surface of the pressing punch 200 is relatively large, the cause of the occurrence of sink marks in the inner peripheral corner is presumed as follows. That is, as the reverse ironing proceeds, the material flows in the cylindrical portion of the material W from the opening side to the bottom side of the material W one after another, and at this time, the outer peripheral edge of the material W is restrained from outside. Is insufficient, the portion of the material W buckles and bends outward, and as a result, sink marks occur at the inner peripheral corners of the material W, and it is estimated that the shape of the inner surface of the material W becomes inaccurate. It is done.

In view of such circumstances, the invention according to claim 1 is characterized in that the distal end surface of the pressing punch is depressed so that the space between the outer peripheral edge of the material and the distal end surface of the pressing punch is relatively small. The object of the present invention is to solve the problem of occurrence of sink marks on the inner peripheral corners of the material due to reverse ironing by restricting the flow of air.

Further, the invention of claim 2 solves the problem that sinking occurs at the inner peripheral corner of the material due to reverse ironing by terminating the reverse ironing before the sink occurs at the inner peripheral corner of the material. This was done as an issue.

[0018]

The gist of the present invention resides in that the bottom of a cylindrical container-shaped material covered on one end of a cylindrical ironing punch is formed in a cylindrical shape from the side opposite to the ironing punch. Pressing the material into the die hole formed in the die together with the ironing punch by pressing the punch into the die, the cylindrical part of the material is pressed from the opening side to the bottom side of the ironing punch and the outer peripheral surface of the die. In the ironing device, the recess is formed on the tip surface of the pushing punch in close contact with the bottom of the material.

The gist of the invention of claim 2 is that a cylindrical container-shaped material is covered on one end of a cylindrical ironing punch,
Press the cylindrical pressing punch from the side opposite to the ironing punch on the bottom of the material and iron the material together with the ironing punch,
By pushing into the die hole formed in the die, the cylindrical part of the material is ironed from the opening side to the bottom side of the ironing punch in cooperation with the outer peripheral surface of the punch and the ironing surface of the die hole. One ironing operation is to finish before the bottom end of the parallel portion of the cylindrical portion of the material reaches the material introduction side end of the ironing surface of the die hole.

Both of the inventions of claims 1 and 2 can be applied to a stainless steel material having an unstable austenite phase, a high-strength material, or a general material. It can also be applied to

[0021]

In the reverse ironing device according to the first aspect of the present invention, since the pushing punch has a concave portion on its front end surface which is in close contact with the bottom of the raw material, the outer peripheral edge of the raw material and the tip of the punch are formed. The space between the surface and the surface becomes relatively small, and the material is confined by the concave portion and flows. Therefore, buckling of the outer peripheral edge of the material W is prevented, and sinkage to the inner peripheral corner of the material is prevented. Is done.

Further, in the reverse ironing method according to the second aspect of the present invention, one time before the bottom end of the parallel portion of the cylindrical portion of the material reaches the material introduction side end of the ironing surface of the die hole. The ironing is ended. Therefore, for example, one time before the bottom end of the parallel part of the cylindrical part of the material reaches the material introduction side end of the ironing surface of the die hole, and before the sink occurs at the inner peripheral corner of the material. If one reverse ironing is completed at one time, the occurrence of sink marks on the inner peripheral corner of the material is prevented.

[0023]

As described above, according to the first aspect of the present invention,
By taking a relatively simple and inexpensive countermeasure such as changing the pushing punch to the conventional reverse ironing device, an effect of preventing sink marks from being generated at the inner peripheral corner of the material due to the reverse ironing can be obtained.

Further, according to the second aspect of the present invention, it is possible to prevent the sinking of the inner peripheral corner of the material due to the reverse ironing without substantially changing the mechanical parts required for the reverse ironing. The effect is obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below in detail with reference to the drawings.

First, a reverse ironing device according to an embodiment of the present invention will be described.

This reverse ironing apparatus performs a plurality of steps by sequentially feeding a material to a next step by a feeder every time one step is completed, thereby forming a plate made of austenitic stainless steel (SUS630, SUS631, etc.). Is placed in a transfer press that forms the material into a cylindrical container. In this transfer press, in addition to the reverse ironing device, a blanking device, a squeezing device, a correct ironing device, and an ironing coining device are also arranged. In the transfer press, a blanking device, a squeezing device, a correct ironing device, a reverse ironing device, and an ironing coining device are arranged in this order.

The basic configuration of the transfer press (including the feed device), the configuration of the blanking device, the squeezing device, and the corrector device are well-known, and detailed description thereof will be omitted. A circular material is punched from a plate-shaped material. In the drawing process, four times of drawing are performed in order, and the mold clearance (one-sided clearance between the punch and the die) for each time is set as the first drawing: 1 0.08t ₀ Second aperture: 0.91t ₀ Third aperture: 0.94t ₀ Fourth aperture: 1.04t _0, and the ironing process is a single ironing process (corresponding to the conventional ironing). ) And the ironing rate is 8.9%
It is supposed to be performed as.

Here, “t ₀ ” represents the thickness of the material before ironing, and the ironing rate is defined by the following equation. ((T ₀ −t ₁ ) / t ₀ ) · 100 where “t ₁ ” represents the thickness after ironing.

The configuration of the reverse ironing device and the configuration of the ironing coining device are new to the blanking device, the squeezing device, and the correct ironing device, and thus will be described in detail.

The reverse ironing device performs reverse ironing on a cylindrical container-shaped material formed by a drawing device. The dimensions and the ironing rate of the material before the reverse ironing are as follows.

Outer diameter: 8 mm Radius of curvature of the outer peripheral edge of the material: 1.5 mm Ironing rate: 7.5% Length: 12 mm

As shown in FIG. 1, the reverse ironing apparatus includes a pushing punch 10 and a die 12. Push punch 1
0 is moved up and down by a driving device (not shown), while the die 12 is fixed to the base 14. Pressing punch 10
2 (an enlarged view of a portion A in FIG. 1)
As shown in FIG. 5, a concave portion 18 is formed in close contact with the bottom of the material W. The concave portion 18 is composed of a central circular flat portion and a protrusion 22 arranged along the circumference thereof. The various dimensions of the concave portion 18 are related to the various dimensions of the bottom of the raw material W before processing so that the central portion of the concave portion 18 and the central portion of the bottom of the raw material W always adhere to each other.
Is set so that an appropriate radial clearance is ensured between them.

The die 12 has a stepped die hole 24 as shown in FIG. This die hole 24
Introducing hole 25, small-diameter hole 2 in order from the upper side to the lower side
6, a medium diameter hole 28 and a large diameter hole 30. As shown in FIG. 3 (an enlarged view of a portion B in FIG. 1), the introduction hole 25 has a curved surface that gradually approaches the axis as it descends along the axis. On the other hand, small diameter hole 26, medium diameter hole 2
8 and the large-diameter hole 30 are both cylindrical surfaces.
An ironing punch 34 is inserted into the die hole 24.
0, and is arranged to be able to move up and down. As shown in FIG. 1, the ironing punch 34 has a flange portion 38, which is a large hole 30 and a medium hole 28 of the die hole 24.
The upper end position is defined by abutting the shoulder between them. The tip of the ironing punch 34 is covered with a material W, and in this state, the ironing punch 34 works together with the small-diameter hole 26 so as to squeeze the cylindrical portion of the material W. It functions as the surface 27. A cushion pin 46 is arranged below the ironing punch 34 so as to be vertically movable, and constantly urges the ironing punch 34 toward an upper end position (a position shown in the left half of the drawing).

A sleeve-shaped stripper 50 is slidably fitted on the outer periphery of the ironing punch 34. The stripper 50 also has a flange portion 52, and the stripper 50 and the flange portion 38 of the ironing punch 34 are arranged so as to be in contact with each other. A plurality of knockout pins 56 are disposed below the stripper 50 so as to be vertically movable. Each of the knockout pins 56 passes through the flange portion 38 of the ironing punch 34. The knockout pins 56 are always in the inoperative position, which is the position shown in the left half of the figure with respect to the ironing punch 34, but from this state, they are raised with respect to the ironing punch 34 and project from their flanges 38. If so, the material W is discharged from the ironing punch 34 via the stripper 50. The upper end position of the stripper 50 is defined by abutting the shoulder portion between the small diameter hole 26 and the medium diameter hole 28 of the die hole 24 at the flange portion 52 thereof.

Next, the operation of the reverse ironing device will be described.

Before the start of one process, the pushing punch 10 is retracted upward from the position shown in the left half of the figure, while the ironing punch 34 and the stripper 50 are at the upper end position. At this time, the upper end surface of the stripper 50 coincides with the upper end surface of the ironing punch 34 or is located at a higher position. The transfer device of the transfer press has a grip finger for gripping the material W, and the material W is sent to the next process by moving the material horizontally, so that when the material W is moved horizontally, the lower end surface thereof moves. The upper end surface of the ironing punch 34 does not protrude from the upper end surface of the stripper 50 so as not to hit the tip of the ironing punch 34. In this state, the material W discharged from the drawing device is gripped by the grip fingers, and is positioned at the processing start position immediately above the ironing punch 34. The lower end surface of the material W coincides with the upper end surface of the stripper 50, and the material W is put on the stripper 50.

In this reverse ironing apparatus, FIG.
Unlike the reverse ironing device shown in FIG.
8 does not have a function of regulating the height dimension of the material W and is exclusively used for paying out. Therefore, the tip surface of the stripper 50 contacts the opening end surface of the material W. It has never been so. In addition,
In the figure, a space is drawn between the tip end surface of the stripper 50 and the opening end surface of the material W. However, this is merely done for convenience of explanation, and in fact, it is almost in close contact. I have.

When the positioning of the material W is completed as described above, one reverse ironing is started, and first, the pushing punch 10 is lowered, and eventually engages with the bottom of the material W. If the pushing punch 10 is further lowered, the raw material W is lowered integrally therewith. As a result, the raw material W is covered on the tip of the ironing punch 34. In addition, between the outer peripheral surface of the ironing punch 34 and the inner peripheral surface of the material W,
As shown in FIG. 2, since the material W is designed so that the clearance S always exists in the radial direction, the material W is smoothly covered on the tip of the ironing punch 34.

When the press punch 10 is further lowered, the press punch 10 is pushed through the material W and the punch 34 is pressed.
With the tip surface of Thereafter, if the working force of the punch 10 overcomes the sum of the lifting force of the cushion pin 46 and the weak reaction force of the knockout pin 56, the pressing punch 1
0 lowers the material W, the ironing punch 34, the stripper 50, the cushion pin 46, and the knockout pin 56 integrally. The lifting force of the cushion pin 46 is set to a magnitude necessary for the upper end surface of the ironing punch 34 to be in close contact with the inner surface of the bottom of the material W.

As a result of the material W and the ironing punch 34 being lowered with respect to the die 12 as a fixing member, as shown in FIG.
The material W is squeezed from the opening side to the bottom side while being sandwiched between the ironing surface 27 and the material flows from the opening side of the material W to the bottom side in the cylindrical portion. become. In this reverse ironing device, as described above, the concave portion 18 is formed on the distal end surface of the pushing punch 10 as shown in FIG. For this reason, when the material flows from the opening side to the bottom side in the material W, the flow of the material is restrained by the concave portion 18 of the pushing punch 10, and as a result, a portion of the material W connecting the cylindrical portion and the bottom portion is formed. Buckling due to axial compression force due to reverse ironing is prevented.

Since the pushing punch 10 is further lowered, when the lower end surface of the ironing punch 34 comes into contact with the upper surface of the base 14, one reverse ironing is completed. As mentioned above,
In the case of reverse ironing, the flow of the material of the material W is caused by the pushing punch 1
0, the buckling of the material W is less likely to occur, and the inner peripheral corners of the material W are less likely to sink, so that the material W eventually becomes as shown in FIG. The outer surface of the bottom has a shape corresponding to the distal end surface of the pressing punch 10.

When the lower end surface of the ironing punch 34 comes into contact with the upper surface of the base 14, the bottom end (indicated by “P _W ” in FIGS. 2 and 3) of the parallel portion of the cylindrical portion of the material W is ironed. The end of the surface 27 on the material introduction side (“P _D ” in FIG. 3)
) Or a position slightly below. FIG. 3 shows the ends P _W and P
An example is shown in which _D matches. That is, in this reverse ironing apparatus, one reverse ironing operation is completed after the entire parallel portion of the cylindrical portion of the material W is ironed by the ironing surface 27 in order.

When one reverse ironing operation is completed as described above, the pushing punch 10 is raised, and accordingly, the ironing punch 34, the material W and the like are integrally raised by the lifting force of the cushion pin 46. . During this rise,
As shown in the left half of FIG. 1, the ironing punch 34 abuts on the lower shoulder of the die hole 24 at the flange portion 38 and is left at the upper end position. Thereafter, the knockout pin 56 is lifted by a driving device (not shown). Is given, the stripper 50 is raised relatively to the ironing punch 34, and as a result, the material W is paid out from the ironing punch 34. This completes one process.

Thereafter, the discharged material W is gripped by the grip fingers and immediately conveyed to the ironing coining device which is the next step.

The ironing coining device performs the common ironing on the material W after the reverse ironing and simultaneously performs the coining. Specifically, as shown in FIG. 4, an ironing punch 70 that can be moved up and down, a die 72 as a fixing member, and a coining punch 74 as a fixing member are provided. And this ironing coining device,
The material W covered on one end of the ironing punch 70 is
2, the cylindrical portion of the material W is cooperated with the outer peripheral surface of the ironing punch 70 and the ironing surface of the die hole 78 together with the cylindrical portion of the material W from its bottom side toward the opening side. Really. Further, immediately before the ironing is finished, the bottom of the material W is pressed against the tip end surface of the coining punch 74 by the ironing punch 70,
The concave portion 80 formed on the distal end surface of the ironing punch 70 and the convex portion 82 formed on the distal end surface of the coining punch 74 cooperate with each other to sandwich the bottom of the raw material W to form an uneven shape thereon.

It should be noted that the material W having been ironed and coined in this way is carried out of the transfer press and carried into the next step, a cutting device (not shown). In this cutting device, as shown in FIG. 5, the outer surface of the bottom of the raw material W is cut into a flat surface, so that the bottom of the raw material W becomes a convex portion at the center thereof and the outer peripheral portion thereof. In this case, the thickness is reduced. The product is completed as described above. This is a component of the pressure sensor that detects the pressure in the combustion chamber of the engine of the vehicle, and the diaphragm that is displaced according to the pressure and the housing of the pressure sensor are integrated. Is formed. That is, the outer peripheral portion (thinned portion) of the bottom of the material W functions as a hinge, and the bottom can be elastically deformed in a direction perpendicular to the surface thereof. Therefore, if a sink occurs in a portion functioning as the hinge portion, stress tends to concentrate on the portion, which may lead to breakage of the diaphragm. Therefore, with respect to this material W, it is difficult to prevent sink mark. Especially important.

By the way, the present applicant has carried out the following measurement in order to confirm the effect of preventing reverse cracking caused by reverse ironing. That is, the axial distribution of the residual stress on the outer surface of the material W was measured immediately after drawing, right after ironing, immediately after reverse ironing, and immediately after ironing. The results are graphically shown in FIGS. 6, 7, 8, and 9, respectively. Each graph shows how the residual stress changes from the opening end of the material W toward the bottom.

When the drawing and the ironing are performed, the residual stress of the material W shifts to the tensile stress side (hereinafter, the residual stress increases). It is in a state where cracks are likely to occur. However, in the present embodiment, the drawing step is performed simultaneously with the correct ironing (as described above, the mold clearance is set smaller than usual), and between the correct ironing and the ironing. In reverse ironing, the residual stress increased by the drawing and the correct ironing is sufficiently reduced by the reverse ironing, and the residual stress is also substantially reduced in the entire axial direction by the ironing afterwards. Since it is maintained on the compressive stress side, the placement crack is reliably prevented.
From this, the following can be understood. In other words, when a process of increasing the residual stress at the opening end of the material W is performed, such as drawing or correct ironing or ironing, when the reverse ironing is performed immediately after that or immediately before the reverse ironing, It is also found that it is effective in preventing cracks.

It should be noted that, when ironing is performed, regardless of whether the ironing is correct or not, so-called ears are usually generated at the opening end of the material W. However, due to the difference in the flow direction of the material due to the ironing, the tendency is correct for the correct ironing than for the reverse ironing. Due to the presence of such ears, the residual stress at the open end of the material W is not uniform over its entire circumference, and the lowest portion thereof is usually closer to the tensile stress at the highest portion. Die 1
When the die 2 is the highest in the open end of the material W, there is no material between the die 12 and the portion of the open end of the material W other than the highest, and the die 12 This is because it is impossible to apply a circumferential compressive stress as scheduled to the portion. Under such circumstances, in this embodiment, the graphs of FIGS. 7 to 9 all assume a straight line that passes through the lowest part of the opening end surface of the cylindrical portion of the material W and extends in parallel to the axial direction thereof. In this case, the distribution of the residual stress on the assumed straight line in the cylindrical portion is shown. Only the distribution of the residual stress relating to the lowest part where the tensile stress becomes large among the open ends is representatively shown.

Further, in this embodiment, the following specific effects can be obtained.

In the conventional reverse ironing apparatus shown in FIG. 14, in order to finish the reverse ironing and to discharge the material W from the ironing punch 34, the eject pin 224 is projected from the center of the tip end surface of the ironing punch 34, The material W was pushed out of the punch 34 by being inserted into the bottom of the W. Therefore, in a state in which the discharged material W is covered with the eject pins 224, access to the material W by the grip fingers for movement to the next process is awaited. At this time, if the grip finger moves the material W horizontally immediately, the cylindrical portion of the material W hits the eject pin 224. Therefore, the material W is first lifted and separated from the eject pin 224, and then the material W
Is moved horizontally and is carried into the processing machine in the next process. As described above, when the conventional reverse ironing device is used, it is necessary that the grip fingers be of a type capable of not only horizontal movement but also vertical movement. There was a problem that such equipment costs would increase.

On the other hand, in the reverse ironing apparatus according to the present embodiment, as shown in FIG. 1, the material W is paid out from the ironing punch 34 by a sleeve-shaped fitting fitted on the outer periphery of the ironing punch 34. The stripper 50 is engaged with the opening end face of the material W and is pulled out of the ironing punch 34. Further, in this embodiment, when the stripper 50 is at the upper end position, the ironing punch 34 is located at the same or lower position. Therefore, in the present embodiment, the grip fingers are supported by the stripper 50 at the open end face both when the material is sent from the drawing device to the reverse ironing device and before the material is sent from the reverse ironing device to the ironing coining device before processing. It is possible to simply move the material W horizontally, and it is not essential that the grip fingers be of a type that allows vertical movement, and the unique effect that the equipment cost for the transfer press can be easily reduced can be obtained. It is done.

Further, the reverse ironing device of this embodiment is
Unlike the conventional reverse ironing device shown in FIG. 14, the cylindrical portion of the material W is not made tight by sealing it. Instead, the cylindrical portion is made intensive and the ironing position is advanced in order to make one reverse ironing operation. Is what you do. For this reason, the length of the ironing surface 27 of the die 12 is shorter than that of the conventional reverse ironing device, so that the working force required for the reverse ironing can be reduced, and the unique effect that the capability of the reverse ironing device can be easily reduced is obtained. Can be

Furthermore, in the reverse ironing apparatus of this embodiment, since the outer peripheral edge of the cylindrical portion of the material W is reliably prevented from bending outward by the concave portion 18, the parallel portion of the cylindrical portion (see FIG. 3) can be effectively secured, and the effect that the height of the material W required to secure the parallel portion having the same length can be reduced can be obtained.

Next, a reverse ironing apparatus according to another embodiment of the present invention will be described. In addition, since this reverse ironing device has the same basic configuration as the reverse ironing device of FIG. 1, the common elements are denoted by the same reference numerals, detailed description thereof will be omitted, and only different portions will be described in detail. .

In this inverted ironing apparatus, as shown in FIG.
Are provided in place of the cushion pins 46. The shaft 90 is moved up and down by a driving device (not shown). However, since the upper end of the shaft 90 is fixed to the lower end of the ironing punch 34 by means of screwing or the like, the ironing punch 34 moves up and down integrally with the shaft 90. Let me do.
In this reverse ironing apparatus, the die hole 92 of the die 12 is a stepped hole mainly composed of two cylindrical surfaces,
In order from the upper side to the lower side, the introduction hole 93 and the small-diameter hole 94
And a large-diameter hole 96. The cylindrical surface of the small diameter hole 94 functions as an ironing surface 98.

Although the drawing shows a state in which the die 12 is composed of a plurality of members, the same applies to the previous embodiment, and the configuration will be described in detail here. That is, the die 12 includes a main body 100, an ironing part 102, and a mounting member 104 each having a generally cylindrical shape.
Are provided as main components, and the ironing portion 102 is
The small-diameter hole 94 is detachably mounted by a mounting member 104 so that the small-diameter hole 94 is accurately centered with respect to the pressing punch 10. In addition, only the ironing portion 102 of these main components is made of a substantially hard metal (ultra-hard), and the other components are made of a metal having a general hardness.

The operation of the reverse ironing device configured as described above is basically the same as that of the above-described reverse ironing device, and the mounting of the material W before processing on the ironing punch 34 and the ironing of the material W after processing are performed. Since the difference is only in the payout from the punch 34, only the portion will be described, and the description of the common portion will be omitted.

Immediately before the start of machining, the stripper 5
0 is a knockout pin 56, and its flange 5
2 is located at the upper end position in contact with the lower surface of the ironing portion 102,
On the other hand, the ironing punch 34 is held by the shaft 90 at the position shown in the left half of the drawing, that is, the tip surface of the ironing punch 34 matches or is slightly lower than the tip surface of the stripper 50 at the upper end position. ing.

In this state, the grip fingers (not shown) carry in the raw material W from the previous process and position it just above the ironing punch 34. Thereafter, the ironing punch 34 moves up together with the shaft 90, and the material W is put on the tip of the ironing punch 34. When the front end surface of the ironing punch 34 comes into close contact with the inner surface of the bottom of the material W, the pushing punch 10 is lowered to engage the outer surface of the bottom of the material W. After that, when the working force of the punch 10 is increased to overcome the lifting force of the shaft 90, the material W, the ironing punch 34, the shaft 90, and the stripper 50 are lowered as the punch 10 is lowered. And the knockout pin 56 is integrally lowered. During this time, a reverse ironing is performed on the cylindrical portion of the material W. Thereafter, when the ironing punch 34 reaches the lower end position shown in the right half of the figure, one reverse ironing is completed.

In this reverse ironing apparatus, as in the case of the above-described reverse ironing apparatus, one reverse ironing operation is completed after the entire parallel portion of the cylindrical portion of the material W is ironed by the ironing surface 98 in order. Has become.

Immediately after one reverse ironing operation is completed, the ironing punch 34 and the like are in the state shown in the right half of the figure. Thereafter, in order to pay out the material W from the ironing punch 34, first, the pushing punch is used. 10, the ironing punch 34, the material W, the stripper 50, and the like are integrally raised by the lifting force of the shaft 90, and the pushing punch 10 is eventually retracted to the non-operating position. The ironing punch 34 and the like reach the upper end position.

Thereafter, the knockout pin 56 is stopped and the stripper 50 is also stopped, while the shaft 90 is lowered, so that the ironing punch 34 is lowered while leaving the material W after processing on the upper end surface of the stripper 50. Thereafter, the grip fingers grip the material W and carry it out to the next step. This completes one process.

As described above, in the present embodiment, the material W is not paid out from the ironing punch 34 by raising the stripper 50 with respect to the ironing punch 34 in the stopped state as in the previous embodiment. The material W is discharged from the ironing punch 34 by lowering the ironing punch 34 with respect to the stripper 50 in a stopped state. Therefore, in the present embodiment, as in the previous embodiment, when the material W is paid out, a downward force is applied instead of an upward force to the material W. 34 side,
The material W is reliably prevented from jumping from the upper end surface of the stripper 50 and becoming unable to be gripped by the grip fingers.

Next, a reverse ironing apparatus according to still another embodiment of the present invention will be described. In addition, since this inverted ironing device has the same basic configuration as the inverted ironing device of FIG. 1, detailed description will be omitted by assigning the same reference numerals to the common portions, and only different portions will be described in detail. .

As shown in FIG. 11, the reverse ironing device includes a pushing punch 120 instead of the pushing punch 10 of FIG. The pressing punch 120 is used for the pressing punch 10.
Unlike the material W, a concave portion 122 having a diameter larger than that of the material W and being in close contact with all portions of the material W except for a parallel portion of the cylindrical portion is formed on the distal end surface. Recess 1 that adheres to the bottom of material W not only in the axial direction but also in the radial direction
22 are formed. Since the pressing punch 120 is larger in diameter than the material W and cannot be inserted into the die hole 128 of the die 126, in this reverse ironing apparatus, as shown in FIG. The state immediately after the completion of the reverse ironing is indicated by a two-dot chain line), and when the pressing punch 120 is lowered to its lower end position, the tip surface (the portion other than the recess 122) of the pressing punch 120 is placed on the upper surface of the die 126. The specifications of the pressing punch 120 and the die 126 are set so that they do not touch each other.

Also, in this embodiment, unlike the previous embodiment, the die hole 128 of the die 126 has an upper tapered hole 130 whose diameter decreases as it moves downward, and a land portion 132 (which is a parallel hole). This is one aspect of the “ironing surface” in the first aspect of the present invention), and a lower tapered hole 134 whose diameter increases as it proceeds downward is connected in series with each other. The pushing punch 120 is hollow, and a discharge pin 136 is provided in the hollow hole so as to be vertically movable. The discharge pin 136 is operated to discharge the processed material W, which is in close contact with the concave portion 122, from the press punch 120.

As described above, in this embodiment, the distal end surface of the pressing punch 120 is at the bottom of the material W (including the bent portion).
Since the shape of the entire outer peripheral edge of the bottom of the material W is determined by the shape of the distal end surface of the pressing punch 120, the shape of the outer peripheral edge of the bottom can be relatively freely and accurately formed. The effect that it becomes possible is obtained.

Although several embodiments of the invention of claim 1 have been described above, the invention of claim 1 can be implemented in other modes.

For example, in each of the above-described embodiments, the pushing punches 10 and 120 are arranged on the upper side and the ironing punch 34 is arranged on the lower side. However, they can be turned upside down or leveled. The invention of claim 1 can be carried out so as to be inclined at an appropriate angle. In addition, in the case of employing a reverse ironing device in which the pushing punches 10 and 120 are on the lower side and the ironing punch 34 is on the upper side, gravity can be positively used to pay out the material W from the ironing punch 34. The effect is obtained.

In each of the above-described embodiments, it is important to generate compressive residual stress in the cylindrical portion of the material W to reliably prevent cracks in place, and the accuracy of the height of the cylindrical portion of the material W is important. Was not so important, for example,
The invention according to claim 1, wherein the accuracy of the height dimension of the cylindrical portion of the material W is improved by ironing the entire cylindrical portion of the material W in a sealed state as in the reverse ironing device of FIG. Can also.

Next, an inverted ironing method according to an embodiment of the present invention will be described.

As shown in FIG. 12, the reverse ironing device for carrying out this reverse ironing method has the same basic configuration as that shown in FIG. The shape of the die hole differs from that of the die. That is, the distal end face of the pushing punch 150 is an enlarged view of a part A in FIG.
As shown in FIG. 12 and FIG. 12, the die hole 154 of the die 152 has an upper tapered hole 156 and a land having a cylindrical surface. The portion 158 and the lower tapered hole 160, and the medium-diameter hole 28 and the large-diameter hole 30 are arranged in that order.

In the reverse ironing by the above-mentioned reverse ironing device, the bottom end of the parallel portion of the cylindrical portion of the raw material W (hereinafter referred to as a bending start line of the raw material W; indicated by “P _W ” in FIG. 13) is ironed. The end of the surface on the material introduction side, that is, the end of the land portion 158 in the present embodiment on the material introduction side (hereinafter, referred to as an entrance end of the land portion 158; indicated by “P _D ” in the drawing). The state at that time is indicated by a two-dot chain line in the drawing), or one reverse ironing operation is terminated when it reaches a position below the entrance end of the land portion 158. However, in the reverse ironing method according to the present embodiment, a position in front of the bending start line of the material W by a certain distance (represented by “L” in the drawing) is set as the reverse ironing end position, which is the land portion 158. One reverse ironing ends when it reaches the entrance end. The distance L is a length that has been experimentally confirmed that sink marks do not start to occur at the inner peripheral corners of the material W due to reverse ironing.

Accordingly, in the present embodiment, sinkage is prevented from being generated at the inner peripheral corner of the material W without performing any special processing on the distal end surface of the pressing punch 150.
An effect is obtained that sink prevention can be performed at low cost.

It should be noted that, in the above description,
Although the ironing rate was set to a value not sufficiently close to 0, such as about 8%, the reverse ironing that changes only the outer diameter and the inner diameter without changing the wall thickness at all or only slightly, that is, the ironing rate is Even in the case of reverse ironing close enough to 0, there is a case where the effect of preventing the material W from being cracked and the effect of preventing sinking to the inner peripheral corner due to the ironing can be simultaneously enjoyed. In this case, if the ironing force is originally large, or if the durability of the lubricating oil applied to the inner surface of the die hole and the outer surface of the material W is insufficient, these problems are not so large. The effect of not being serious is obtained.

Further, when the reverse ironing according to each of the first and second aspects of the present invention is employed, it is possible to improve the processing accuracy, surface roughness, etc., as in the case of the conventional ironing. Rather, the effect of reducing the height fluctuation of the material (including fluctuation due to the occurrence of ears) can be obtained as compared with the conventional ironing. In the case of conventional ironing, the material flows during the ironing from the bottom side of the material to the opening side, and the excess material generated by the ironing fills the opening of the material, causing the height of the material to fluctuate. easy. In contrast, in the reverse ironing according to the present invention, there is almost no tendency that the material flows from the bottom side of the material to the opening side and is filled in the opening during the ironing, and the material is the material. Flow from the opening side to the bottom side of the material, and most of the surplus generated by the ironing is filled in the space between the outer surface of the bottom and the tip surface of the punch, so the height of the material fluctuates It is difficult to do.

Although some embodiments of the present invention have been described in detail with reference to the drawings, the present invention may be modified in various other ways based on the knowledge of those skilled in the art. Can be implemented.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an inverted ironing device according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a portion A in FIG. 1;

FIG. 3 is an enlarged view showing a portion B in FIG. 1;

FIG. 4 is a front sectional view for explaining an ironing coining device arranged downstream of the reverse ironing device of FIG. 1;

FIG. 5 is a front sectional view showing a product finally obtained by cutting the material W processed by the ironing coining device of FIG. 4;

6 is a graph showing an example of an axial distribution of residual stress on the outer surface of a cylindrical portion of a material W processed by a drawing device arranged upstream of the reverse ironing device of FIG. 1;

FIG. 7 is a graph showing an example of the distribution of residual stress in the axial direction when the material W in FIG. 6 is correctly ironed.

8 is a graph illustrating an example of an axial distribution of residual stress when reverse ironing is performed on the material W of FIG. 7;

9 is a graph showing an example of an axial distribution of residual stress when ironing is performed on the material W of FIG. 8;

FIG. 10 is a front sectional view showing an inverted ironing apparatus according to another embodiment of the first invention.

FIG. 11 is a partial front sectional view showing a portion of the inverted ironing device according to still another embodiment of the present invention, which is different from the inverted ironing device of FIG. 1;

FIG. 12 is a front sectional view showing a reverse ironing apparatus for performing the reverse ironing method according to one embodiment of the present invention;

FIG. 13 is an enlarged view showing a portion A in FIG. 12;

FIG. 14 is a front sectional view showing a conventional reverse ironing device.

FIG. 15 is an enlarged view showing a portion A in FIG. 14;

FIG. 16 is an enlarged view showing a portion B in FIG. 14;

FIG. 17 is a front cross-sectional view for explaining the characteristics of the stress generated in the cylindrical portion of the material W by the conventional ironing.

FIG. 18 is a front cross-sectional view for explaining the characteristics of the stress generated in the cylindrical portion of the raw material W due to reverse ironing.

FIG. 19 is a perspective view showing an example of a material made of austenitic stainless steel, in which a placement crack has occurred.

[Explanation of symbols]

 10, 120, 150 Indentation punch 12, 126, 152 Die 18, 122 Recess 24, 128, 154 Die hole 27, 98 Ironing surface 34 Ironing punch 132, 158 Land portion

Claims (2)

(57) [Claims] 1. A cylindrical pressing punch is pressed against the bottom of a cylindrical container material covered at one end of a cylindrical ironing punch from the side opposite to the ironing punch, and the material is pressed together with the ironing punch. By pressing the cylindrical portion of the material from the opening side to the bottom side of the die by pressing it into the die hole formed in the die, the outer peripheral surface of the punch and the ironing surface of the die hole are cooperated with each other and the ironing device is turned upside down. The reverse ironing device according to any one of claims 1 to 3, wherein a concave portion is formed on a tip end surface of the pushing punch so as to be in close contact with a bottom portion of the material. 2. A cylindrical ironing punch is covered with a cylindrical container-shaped material on one end thereof, and a cylindrical pressing punch is pressed against the bottom of the material from the side opposite to the ironing punch to form the material into an ironing punch. Together, the material is pressed into the die hole formed in the die, and the cylindrical portion of the material is ironed from the opening side to the bottom side of the ironing punch together with the ironing surface of the punch and the ironing surface of the die hole. In the ironing method, one ironing is completed before the bottom end of the parallel portion of the cylindrical portion of the material does not reach the material introduction side end of the ironing surface of the die hole. .