JPS5817690B2 - Cold forming mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold-open mold, particularly a double or triple-fit cold-open mold.

Cold forging is a processing method that applies pressure to a metal material with a tool at room temperature or below the recrystallization temperature of the material, and extrudes or fills the metal material along the shape of the tool to create objects of a predetermined shape.It improves the mechanical properties of the material. However, it has the advantage of being mass-produced with product precision comparable to cutting, but it has greater deformation resistance than hot forging, and there are restrictions on the capacity of processing machines and the strength of mold tools.

Fig. 1 shows the configuration of a forward extrusion cold forming die. Reference numerals 11 and 12 are the upper and lower dies for metal members made of cemented carbide, respectively, and the outer periphery is 5KD (high platform). A first shrink-fitting ring 13 made of gold cold die steel)-61 is shrink-fitted, and furthermore, SNCM (structural alloy steel) is attached to the outer periphery.
A second shrink-fitting ring 14 consisting of 18 is shrink-fitted, and this cold-opening mold is used to form a blank 15 shown in FIG. 2a.
From this, a front extrusion part 16 as shown in the figure is obtained.

For large molds that generate high stress, such as this forward extrusion mold, there is a problem that unless double or triple fitting is used, the internal pressure will cause the mold to expand in the radial direction, so double or triple fitting was necessary. On the other hand, increasing the pressure in the radial direction causes the shrink-fit ring to elongate in the axial direction.

That is, as shown in Fig. 1, compressive stress 17.17 acts on the first shrink-fit ring 13 from the inside and outside, so it expands 18 in the axial direction.
, and the axial stress due to heat shrinkage due to initial shrink-fitting is alleviated.

Of the axial stress, the axial stress 20 (σA'
) becomes particularly small, so when the internal pressure is high, the dividing surface 1
9 will open, and the gap will enter that part, and when the gap enters, the gap will further expand, causing large scratches on the product, making it impossible to work.

Furthermore, Fig. 3 shows the configuration of a compression type cold-opening mold, where 31 is a mold member made of cemented carbide, and 32 is a 5KD-
11 is a mold fixing member, 33 is a first shrink-fitting ring made of 5KD-61, and 34 is a second shrink-fitting ring made of SNCM-8. These are assembled by shrink-fitting and press-fitting, and this cold-opening Using a mold, a compressed part 36 as shown in FIG. 4A is obtained from the blank 135 shown in FIG. 4A.

However, in cold-open molds assembled by press-fitting and shrink-fitting, the tensile stress (σB0) during operation is
The shrink-fitting compressive stress (σB') is distributed as shown at 37 and 38 in Fig. 3, and the maximum stress is at the tensile stress σs0 during operation, and it is impossible to generate the maximum compressive stress at the opening. As a result, the mold was easily damaged and the life of the mold was short.

The present invention aims to eliminate these problems and provide a mold for cold-opening molding that can be processed with high precision and has a long life. In a cold forming mold that is press-fitted and shrink-fitted, the mold member and the cylindrical member or each cylindrical member are connected and constrained by a plastic bonding method.

The invention is characterized in that it has a connecting portion.

Here, the plastic bonding method means that the bonded portion of the first bonded member and the second bonded member has a certain height and length, including a recess provided on the surface of the bonded portion of each bonded member. On the other hand, it is made of a material that has lower deformation resistance than the material of the double-wave coupling member and has a predetermined mechanical strength, and has a height and length that is equal to or similar to the height and length of the cavity. and then inserting this joining member into the aforementioned cavity so that the entire joining member substantially covers both sleeves.

The connecting member is surrounded by the mold, and the mold convex part presses the joining member to plastically flow it into the aforementioned recess,
This refers to a method of joining double-wave joining members using shear force and tension force of the joining members.

Examples will be described below.

FIG. 5 shows an embodiment applied to a front extrusion mold, and the same parts as in FIG. 1 are given the same reference numerals.

In this case, the first shrink-fit ring is divided into an upper ring 21 and a lower ring 22, and the lower ring 22 and the second shrink-fit ring 14 are plastically coupled by a coupling portion 23 made of steel.

Fig. 6 shows the state of formation of the plastic joint, where 22 is the lower ring, 14 is the second shrink-fit ring, and the lower ring 22 has a gap with a width (w) of about 1.5 to 4 mm. A concave portion having a depth d) of about 0.3 to 0.8 mm and an inclination angle (θ) of the outer circumferential portion of 45° is provided on the outer circumferential surface of the gap, and the second shrink-fit ring 14 has the following features: A concave portion having the same depth and outer peripheral inclination as the lower ring side is provided, and a coupling member having a width smaller than W is inserted into the gap between the lower ring 22 and the second shrink-fit ring 14. Then, pressure is applied using the pressing convex portion of the press die 24 having a tip end surface having a width smaller than the width of the gap, and the joining member is plastically deformed and flows into the recessed portions of the lower ring 22 and the second shrink-fit ring 14. A coupling portion 23 is configured.

At this time, the connecting member, except for the part corresponding to the press die 24,
Since it is surrounded by the lower ring 22 and the second shrink-fitting ring 14, the coupling member hardly escapes to the outside of the gap when pressurized.

Furthermore, if the length of the coupling member is made approximately equal to the length of the cavity, the coupling member can be effectively inserted into the recess.

Further, the distance 1 between the end face of the press die 24 and the tips of the recesses of the lower ring 22 and the second shrink-fit ring 14 is selected to be about 0.2 to 2.5 mm.

If this selection is made, the mold can be easily removed after joining, and the joining member will not flow out in the opposite direction to the insertion direction of the mold, that is, out of the cavity, and the insertion depth will be deep. , it is possible to generate a large internal stress in the connecting member, and therefore a large bonding force can be obtained.

The tightening margin is approximately 0.05 mm.

Note that there is a relationship between W and 1 as shown in FIG.

In this figure, 1 is taken on the horizontal axis with W as the unit,
The vertical axis shows torque (ky-m) and axial shear fracture force (k
y) is taken, A is the torque, and B is the axial shear fracture force, and this result shows that 1 is good in the range of O to -W.

Furthermore, θ is determined according to FIG.

The horizontal and vertical axes of this figure are θωυ and axial shear fracture force (#), respectively, and from this figure, θ is 2.
It can be seen that 5 to 70 degrees is desirable.

That is, the upper mold member 11, the first shrink-fitting ring 21
After assembling the second shrink-fit ring 14, the lower mold member 12 and the lower shrink-fit ring 22 are finally press-fitted, and the second shrink-fit ring 22 and the second shrink-fit ring 14 are finally press-fitted. The connecting portion 23 plastically connects them to each other.

Due to this plastic bonding, the stress σA0 (1
A stress σA'' is generated on the dividing surface 19 at a value close to 50 to 230 kg/m7i), and the plastic bonding is completed in this state, so that the mold can be assembled while this stress σA'' is maintained.

Therefore, even if high internal pressure occurs in the mold during operation, the parting surface 1
9 can be worked without opening and no cracks occur, so a mold with a long life can be obtained, and the life of the mold can be extended from 2,500 pieces to 120,000 pieces. Became.

In addition, since the upper mold member and the lower mold member are loosely press-fitted, the burnout effect is approximately 20% higher than before, and cold-open molding has sufficient strength in both the child direction and the axial direction. You can obtain molds for use.

In addition, since it is assembled by plastic bonding, there is no need to apply heat, and whereas conventionally the precision was controlled by the dimensional accuracy of the mold member and the first and second burnout rings, plastic bonding When used, the dimensional accuracy of each member is 1
/3 to 1/4 is sufficient, and the stress can be controlled just by managing the pressure, making it easy to manufacture the mold.Furthermore, if the lower mold member is damaged or worn out, the plastic joint can be scraped off. It is also possible to exchange only the mold.

FIG. 9 shows another example in which the present invention is applied to a compression mold for cold open molding.

The same parts as those in FIG. , a second burnout ring 34, and the first burnout ring 40 and the second burnout ring 34 are plastically connected by a connecting portion 41.

In a cold forming mold having such a structure, the tensile stress σB0 during operation and the burnout compressive stress σB" are 3 in Fig. 9.
7 and 42, and σB0=:=σB"
It can be done.

That is, a ring-shaped coupling member is inserted between the first burnout ring 40 and the second burnout ring 34, and the coupling member is pressurized to cause the material to flow into the groove, thereby forming the coupling portion 4.
1 is configured, and even after the stress is released, the stress that remains inside causes compressive residual stress in the child direction, particularly in the opening.

In addition, by adjusting the pressure p, the value of compressive stress during burnout can be freely controlled, and the value of pressure p can be changed depending on the material actually processed and the processing rate to obtain the optimal compressive stress. It can be brought to life.

Also, σB. Because of this, there is almost no mold damage, and the lifespan of the mold can be extended from 60,000 pieces to 145,000 pieces.

Furthermore, if the compression part mold is damaged or worn out, it can be easily disassembled by scraping off the plastic joint.
The outer ring and lower mold fixing member can be reused, and by simply remaking the mold for the compressed part, it can be used like a new mold.

FIG. 10 shows another embodiment, and similarly to the embodiment of FIG. 9, it shows an example applied to a compression mold for cold forming.

The same parts as in FIGS. 3 and 9 are given the same reference numerals, and the difference from FIG. 3 is that the entire outer periphery of the mold member 31 is The same effect as in FIG. 9 can be obtained in that the connecting portion 43 extending over the length is provided.

As described above, the present invention provides a cold forming mold that can be processed with high precision and has a long life, and is an industrially effective dog.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional front extrusion cold forming die, FIGS. 2a and b are perspective views of a blank and a processed product, respectively, during forward extrusion processing, and FIG. FIGS. 4a and 4b are perspective views of a blank and a processed product during compression processing, respectively, and FIG. 5 is a cross-sectional view of a conventional compression mold for cold-open molding. A cross-sectional view of a sea example in which the mold is applied to a forward extrusion mold, FIG. 6 is a cross-sectional view showing the process of forming a plastic joint, and FIGS. 7 and 8 are lines illustrating the conditions of the plastic joint. 9 and 10 are cross-sectional views of different embodiments in which the cold-opening mold of the present invention is applied to a compression mold. i 11, 12... Mold member, 21, 22.
...First burnout ring, 14...Second burnout ring, 23...Connection portion, 31...Mold member, 32, 39... ... Mold fixing member, 40
. . . 1st burnout ring, 34 . . . 2nd burnout ring, 41. 43 . . . Joint portion.

Claims (1)

[Scope of Claims] 1. In a cold-open forming mold in which concentric cylindrical members are press-fitted into the outer periphery of a mold member in a single or multiple manner and are shrink-fitted, there is a gap between the mold member and the cylindrical member or between the cylindrical member and the cylindrical member. A coupling part that forms a ring-shaped gap between members, inserts a ring-shaped coupling member into the gap, and couples and restrains the mold member and the cylindrical member or the cylindrical members with each other by plastic deformation of the coupling member. A mold for cold open molding, characterized by having the following. 2. The mold member is a forward extrusion mold member consisting of an upper mold and a lower mold, and the cylindrical member corresponding to the lower mold and the cylindrical member press-fitted to the outer periphery of the mold member are combined by plastic deformation of a connecting member, and the A mold for cold open molding according to claim 1, wherein the lower mold is restrained in the axial direction. 3. The cold forming mold according to claim 1, wherein the mold member is a compression mold member, and the mold member is restrained in the compression direction by plastic deformation of a connecting member.