JPS6146339A - Segment assembly type press die - Google Patents

Abstract

PURPOSE:To elevate the accuracy of die by performing a dimensional decision taking into consideration a deformation based on the fastening of a die case as well as by constituting a die tip with plural divided tips of sintered board alloy or ceramics, etc. CONSTITUTION:A die tip is composed of plural upper segment tip 1 and lower segment tip 11. The segment tips 1, 11 are coated with the surface hardening layer of TiC, etc. on sintered board alloy or formed with a ceramics material. The air and dust are released through the space B which is between the lower face of the segment die 1 and the releasing face of the tip 11, also the size of each segment tip 1, 1 is decided in advance taking into consideration the deformation based on the fastening pressure by the die case. Due to the die tip being worked in the most suitable shaped dimension according to this method the dimensional accuracy of a die is elevated.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a press die for cold forging used for bolt formers, nut formers, parts formers, etc., and more specifically, a die tip is supported in a die case. This invention relates to a separate assembly type press mold.

(Prior Art) A press die for cold forging consists of a die tip 1 and a die case fitted to the outer periphery of the die tip by burning out, press fitting, or the like. For the die tip, high speed steel, special steel, etc. can also be used, but cemented carbide etc., which have excellent wear resistance, are preferable. On the other hand, the die case is made of steel and compensates for and reinforces the lack of toughness of the die tip. In this type of press mold, the chips are manufactured by electric discharge machining due to shape problems.

Furthermore, as with other cemented carbide tools, a surface hardening treatment method is carried out to form a hardened layer on the surface of the tool in order to further improve its wear resistance. As this hardened layer, for example, various carbides, nitrides, carbonitrides, borides or silicides of transition metals, and/or A1. Y.

Coating with a single layer, multiple layers, or multiple layers of oxide such as Zr.

(Problems to be Solved by the Invention) By the way, conventional press dies for cold forging have various problems when manufacturing dies with high dimensional accuracy.

(1) When the chip is attached to the die case, the inner surface of the chip contracts due to the tightening pressure from the die case, so the hole diameter is machined taking into account the shrinkage allowance in advance. but,
Since it is difficult to obtain sufficient dimensional accuracy with this method, if a mold with a machined hole with high dimensional accuracy is to be obtained, it is necessary to re-process the inner surface of the die after attaching the die case.

(2) When applying surface hardening treatment to press molds that require high dimensional accuracy, if a die case is attached to a chip that has been surface hardened in advance, the inner surface of the chip will be removed after attaching the die case. must be processed again, and the hardened layer may be scraped off. For this reason, this surface hardening treatment method could not be applied to press molds that require high dimensional accuracy.

Another possible method is to attach the chip to a die case, rework the holes to improve dimensional accuracy, and then perform surface hardening treatment. However, in the case of chemical vapor deposition, which is the most commonly used surface hardening method for this type of press mold, the processing temperature is as high as around 1000°C, and the steel die case is annealed. After that, operations such as quenching and tempering are required, and this heat treatment causes variations in the dimensional accuracy of the mold. For this reason, even with this method, the surface hardening treatment method could not be applied to this type of pre-deposited mold.

(3) Electrical discharge machining requires a long machining time and uses expensive silver, tungsten, etc. for electrodes, resulting in extremely high costs. Furthermore, the discharge surface loses its normal carbide properties due to the formation of a hair crack abnormal layer due to discharge, etc. Therefore, it is necessary to apply even more sufficient lapping, and as a result, it is difficult to achieve high dimensional accuracy. Furthermore, wrapping requires skill and experience. Also,
Material defects caused by electrical discharge machining often remain inside the ultra-hard material, shortening the life of the mold.

On the other hand, when designing a mold, a split assembly design method in which the chip is divided horizontally or vertically is sometimes used for the purpose of dispersing concentrated stress when a sharp shape of a part of the concave corner is required. The split mold makes processing easier and improves processing accuracy.

However, with this split-assembly type press mold, when the split surfaces are matched and assembled, the joint surfaces are flat, so slipping easily occurs on the joint surfaces, and a precision jig is required to join and fit them together. However, there was still a problem that some errors occurred. *In addition, the conventional splitting method has insufficient effects on the shape of the air and dust emitted due to the breathing action during forging work, resulting in damage to the chip due to compressed air and deterioration in the formability of the workpiece material. In another application, the present inventors solved these problems by using a curved surface division method in a horizontally divided divisional assembly type press mold. However, the above problems (1) to (3)
) remained unresolved.

An object of the present invention is to provide a split assembly type pre-deposit mold with high dimensional accuracy.

(Means for Solving the Problems) In the split-assembly press mold comprising a die chip and a die case supporting the die chip according to the present invention, the die chip is aligned in a direction parallel to the die axis at least in the seat forming portion of the workpiece. It is composed of a plurality of divided chips that are overlapped with each other, and the bonding surface of each divided chip is formed into a curved surface that corresponds to the shape of the seat of the workpiece, and at least some of the divided chips are It is composed of multiple partial chips divided in the radial direction according to the shape, and these partial chips have dimensions that take into account deformation due to the clamping pressure of the die case, increasing dimensional accuracy during assembly. shall be.

(Function) According to the present invention, each part constituting the die chip can be assembled with high precision so that there is no need for reprocessing after assembly.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1(a) to 1(d) are perspective views of the die tip of a press mold used in the step of forming the head part of a component nut into a hexagonal shape. This die chip consists of six upper divided chip parts 1 shown in FIG. 1(e) and lower divided chip parts 11 shown in FIG. 1(b). Figure 1(a) shows six parts 1
The top split chip is shown assembled with the two parts in contact with each other. FIG. 1(d) shows an upper divided chip part 1 and a lower divided chip part 11.
The die chip assembled from is shown. The parts 1゜1, . . . that constitute the die chip and the lower divided chip 11 are as follows:
Both are made of cemented carbide, and are coated with Ti by chemical vapor deposition in advance.
C and/or TiC+T1CN, further TiC+T1C
It is coated with a surface hardening layer such as N+Al2O5. *Also, since the electrical discharge machining method is not used for manufacturing, there is no deterioration of the properties of the alloy due to electrical discharge machining, and even if the alloy is covered with a surface hardening layer, it can be manufactured with good dimensional accuracy. Note that, as will be explained later, the component 1 is designed in advance to anticipate deformation due to fitting of the die case and to minimize deformation after assembly.

The part 1 has a flat inner surface 2) a top surface 3, a side surface 4°4,
It has a lower surface 5 and an outer surface 6 which are curved surfaces.

The inner surface 2 forms a hexagonal machined hole 7 on the outside when assembled as shown in FIG. In other words, in this embodiment, the upper divided chip is divided corresponding to the corners of the machined hole.

The lower split chip 11 has a machined hole consisting of a circular inner surface 12 and a hexagonally symmetrical seat forming portion 13, and also has a lower surface 14.
is a plane. The shape of the seat forming portion 33 is formed to correspond to the shape of the seat of the workpiece (workpiece material). The top surface is
In addition to the seat forming part 13, six concave joint surfaces 16, 16. . . . and approximately triangular relief surfaces 17, 17, which are formed, for example, in a plane, on the adjacent joint surfaces 16, 16, and 17. ...is provided. Joint surface 1
6,16. ... are in close contact with the lower surface 5 of the component 1 without any gaps, as shown in FIG. 1(d). Relief surface 17117
+... defines a space between the lower surface 5 and the seat forming portion 13 to the outer periphery of the die chip, forming a space B from which air and dust can escape. As is clear from the shape shown in FIG. 1(d), this escape space B is
3 toward the outer surface 15. Furthermore, corresponding to this space, a vertical groove 1 is provided on the outer surface 15.
8,18. ... is provided up to the lower surface 14.

FIGS. 2(a) and 2(b) show a press mold assembled using the die chips shown in FIGS. 1(,) to (d).

As shown in Figure 1(,), the six parts 1.1. ...
The upper split chip assembled from the above is fitted into the steel die case 21 by burning out, press fitting, or the like.

When increasing the tightening pressure of the die case, use the die case 21.
Divide into concentric circles. In addition, part 1 and lower divided chip 1
1, the die case 21 is supported by a die holder 22, and the lower surface 14 of the lower split chip 11 is supported by a die holder 23, as shown in the cross section taken along line A-A in FIG. 1(d). Ru. During assembly, each element of the chip 1, 1 . ...; 11 is a convex curved surface 5, 5 . ...
and the concave curved surfaces 16° 16, . . . can be brought into close contact and easily and accurately overlapped with each other. That is,
Divided chips 1, 1 due to the above unevenness. ...; Since the parts 11 can be positioned relative to each other both in the radial direction and in the circumferential direction, there is no risk of joint displacement occurring during assembly, and the ease of assembly is significantly improved.

FIG. 3(,) shows four parts 31, 31. of a rectangular stepped mold. 3(b) is a perspective view of the lower divided chip 41. FIG. The press molds shown in Figures 1 (,) to (d) and Figure 2 are essentially the same except that the machined holes are symmetrical on all sides, so a detailed explanation will be omitted. . Each component 31 includes an inner surface 33 that forms a rectangular machined hole 32 and a lower surface 34 that is a convex curved surface that contacts the lower split chip 41 . The lower divided chip 41 is
A circular inner surface 42, a four-way symmetrical seat forming portion 43, and concave joint surfaces 44, 44. ...and relief surfaces 45, 45.・・・
・Groove 46, 46. It is equipped with...

In the press mold shown in Figs.
32 and the relief surface of the lower split tip 11.41, the dust escapes through the space B between the die tip 11 and the relief surface of the lower split tip 11, 41, so there is no damage to the inner surface of the die tip 7 and no dust remains, and the life of the press die is extended. Also, the sagging of the seat has been eliminated, and there is no need to rework the seat.

Incidentally, the inner surface of the die chip forming the machined hole is deformed by the tightening pressure of the die case. Figure 4(a), (
b) shows the contracted state of the parts of the die chip as viewed from the top and from the side, respectively;

Here, Δr is the amount of shrinkage strain on the inner surface, 21 is the angular difference between the chip bonding surfaces, and ΔS and ΔU are the circumferential differences between the die case and the component. FIG. 4(c) is a cross-sectional view of the assembled die chip, where d is the chip inner diameter, D is the chip outer diameter, and L is the length in the die axis direction.

Regarding the ratio D/d between the chip inner diameter d and the outer diameter, if the value of this ratio is less than 1.0, the strength of the die will be insufficient,
On the other hand, if it is larger than 5.0, the shrinkage strain is reduced but it is not economical, so D/d was set to 2.5. Similarly,
Regarding the ratio L/D between the axial length and the outer diameter of the chip, if the value of this ratio is less than 0.1, the rigidity of the die will be insufficient, while if it is greater than 2.0, the rigidity of the die will be insufficient. , the inner diameter of the chip cannot be sufficiently machined, reducing product accuracy. Therefore, L/D was set to 2.0. In addition, these D/d and L
Regarding the value of /D, even if the value changes slightly within the range considering the above-mentioned product accuracy, economical efficiency, etc., it will not affect the effects of the present invention.

For the die chip 1 shown in FIGS. 4(,) to (c),
d/I)-2,5, L/D=2.0. tt=1 minute, Δ
S=0.015. Set Δu=o, o1. The processing is
High precision can be achieved by simply polishing. When a predetermined clamping pressure was applied to the die case during assembly of the press mold, the amount of shrinkage strain Δr was 24 μm.

The shrinkage strain amount Δr is different from the conventional non-divided die chip,
By assembling the die chip from parts with optimal shapes and dimensions, it is possible to suppress the die chip as much as possible.

When manufacturing the die, the angle difference t1 and the circumference difference Δ3. ΔU, etc. are set, and data such as the amount of shrinkage strain with respect to L/D is collected. From this data, the optimum shape and dimensions of the part can be determined. After finishing parts with the optimal shape and dimensions with high precision using only polishing, surface hardening treatment is performed.

A highly accurate press mold can be obtained from the parts thus obtained. Unlike the conventional method, no machining is required to improve accuracy after the stand-up. Therefore, everything can be done by machining without relying on uncertain factors such as skill level as in the past. As a result, variations in the dimensional accuracy of press dies are greatly reduced, making it possible to guarantee product accuracy and die life, which were previously considered impossible.

In the above embodiments, a cemented carbide with surface hardening treatment was used as the die chip material, but Al2O, system 1s;
Ceramic materials such as IN4 type can be used. Compared to cemented carbide, ceramics have a transverse rupture strength of 1/2 or less, have low toughness, and have very little strain. Therefore, when a ceramic material is applied to the die chip, its shrinkage strain can be suppressed to a very small value (0.01 or less), so that a press mold with high precision can be manufactured easily. In this case, there is no need to form a surface hardening layer.

Furthermore, during forging of the workpiece, the surface hardened layer of the chip, such as T i C, T i N , Al 201, etc., or ceramics also acts as a lubricant b, improving the fluidity of the workpiece. This is because the coefficient of friction between the hardened layer or ceramics and the workpiece material, such as steel, is reduced to ⅓ or less compared to the coefficient of friction between steel. Therefore, seizure and galling are less likely to occur when the workpiece slides. The accuracy of the product has therefore been further improved.

Conventionally, when the heading process is divided into several stages, the diameter of the machined hole in the mold used in the subsequent process must be set to a tolerance of 10.
There was a risk that the cemented carbide association mold would cause galling and break the mold. However, when the press mold according to the present invention is used, it becomes possible to perform ironing processing in which the diameter of the machined hole is set to one tolerance in the post-process, and the precision of the product is improved. Furthermore, front and rear extrusion forging, which was previously impossible, is now possible.
The process can be shortened, and the fields of application of heading can be expanded dramatically.

Next, it will be shown that a structure in which press molds are stacked in multiple layers in a direction parallel to the die axis is also effective in reducing the amount of shrinkage strain Δr of the die chip.

Figure 5 shows the amount of shrinkage strain Δr when a die chip with a hexagonal inner surface made of cemented carbide coated with a surface hardening layer is equally divided into n folds (n = 2.3.4). /d is 2.5 and L/D is 2.0 The 0 division surface is a curved surface, therefore, the length of each division chip in the die axis direction! Ha, L/
It is n. When a predetermined tightening pressure was applied, the shrinkage strain amount Δr was 24 μm when not divided, but when divided, Δr was 12 μmt8 μm for n=2.3.4
The diameter gradually decreased to 5 μm. FIG. 6 shows Δr against 1/D and shows the decrease in Δr due to division. Therefore, when multiple division is performed in the die axis direction, Δr
It becomes easier to size the chip to make it smaller.

Although equal division was used in this embodiment, it is clear that shrinkage strain can be reduced even if the division is unequal.

It goes without saying that the present invention can be applied to split-assembly press molds of various shapes.

(Effects of the Invention) According to the present invention, by assembling a die chip from parts that have been pre-processed into optimal shapes and dimensions, a highly accurate press mold can be obtained without having to be reprocessed after assembly.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are perspective views of an upper divided chip and a lower divided chip, respectively, according to an embodiment of the present invention. FIG. 1(c) is a perspective view of parts constituting the upper divided chip. FIG. 1(d) is a perspective view showing the assembly of the upper divided chip and the lower divided chip. FIGS. 2(a) and 2(b) are a sectional view and a top view, respectively, of a press mold according to an embodiment of the present invention. FIGS. 3(a) and 3(b) are perspective views, respectively, of an upper split chip and a lower split chip of the second embodiment of the present invention, and FIGS. 4(a) and 4(b) are respectively, It is a figure which shows the contracted state of the upper surface and side surface of a die chip component. Figure 4(c)
FIG. 2 is a diagram showing the dimensions of a press mold. FIG. 5 is a diagram showing data on the shrinkage strain amount Δr when the die chip is divided into multiple parts using the curved surface division method. FIG. 6 is a graph showing the shrinkage strain amount Δr versus 1/D. 1... Parts of upper split chip, 2... Inner surface, 5...
...Bottom surface (joint surface), 7...Machined hole, 1
1... Lower split chip, 12... Inner surface, 13
... Seat forming part, 16,16.・・・・・・Joint surface, 17.1? , ...missing surface, 18.18.・
...Groove, 21...Die case, 22.23.
...Die holder, 31... Upper split chip parts,
32... Machining hole, 33... Inner surface, 4
1... Lower divided chip, Δr... Shrinkage strain amount. Patent applicant: Ito Choukou Co., Ltd., one representative
People Patent Attorney Blue and White Two Idiots Figure 5 V Mouthful Figure 4 (0) Figure 4 (b) Figure 4 (C)

Claims (3)

[Claims] (1) In a split-assembly press mold consisting of a die chip and a die case that supports it, the die chip is divided into multiple pieces so that they overlap in a direction parallel to the die axis at least in the seat forming part of the workpiece. The joint surface of each divided chip is formed into a curved surface corresponding to the shape of the seat of the workpiece.
At least some of the divided chips are composed of a plurality of partial chips divided in the radial direction according to the shape of the seat, and the partial chips have dimensions that take into account deformation due to tightening pressure by the die case in advance, A split-assembly press mold characterized by high dimensional accuracy during assembly. (2) The split-assembly press mold according to claim 1, wherein the component chip is made of ceramics. (3) In a split-assembly press mold consisting of a die chip and a die case that supports it, the die chip is divided into a plurality of parts so as to overlap in a direction parallel to the die axis at least in the seat forming part of the workpiece. The joint surface of each divided chip is formed into a curved surface corresponding to the shape of the seat of the workpiece.
At least some of the divided chips are composed of a plurality of partial chips divided in the radial direction according to the shape of the seat, and these partial chips are made of steel with a surface hardening layer, and are pre-applied to the clamping pressure by the die case. Equipped with dimensions that take into account deformation due to
A split-assembly press mold characterized by high dimensional accuracy during assembly.