JPH0338012B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a flare wall forming apparatus for forming a flare wall having a tapered hole into a blank made of a cylindrical cup, a cylindrical material, a cut bar, or the like. be.

[Prior Art] Conventionally, when a taper cup product 100 having a flared wall 101 as shown in FIG. 16 is formed by cold heading, the product 100 is
In addition, short-term damage to tools such as dies and punches occurs, which often results in short tool life.

Typical defects in the product are:
As shown in FIG.
As shown in FIG. 8, there is a stress crack 104 occurring in the middle of the flare wall 101 in a direction of about 45 degrees.

"Tearing phenomena" such as the above-mentioned splits and cracks
This occurs when the inner and outer diameters of the cylindrical wall are expanded by forming, as in the case of the flared wall 101, and the tensile ductility of the material of the cylindrical wall exceeds the processing limit. Furthermore, the stress cracks 104 are often caused by a combined force of axial compressive force and circumferential tensile force due to frictional force between the material and the tool. Note that the frictional force is extremely large, sometimes reaching 10 to 15 times the simple compressive stress.

Furthermore, processing heat is generated in the material due to the forging force and friction caused by the forming, and the temperature of the processing heat often reaches the blue brittle region, further deteriorating the workability of the material, resulting in product defects and tool life. This is the cause of the shortening.

Further, Japanese Patent Publication No. 49-44867 (Patent Registration No. 797314) discloses a cold heading method and a cold heading apparatus for a metal cup having a pointed edge.
The above publication discloses that a flared wall is formed by compressing the flared wall over its entire circumference and expanding it in the circumferential direction by setting an appropriate taper angle of the inner wall of the die. .

This will be explained in detail with reference to FIG. Note that the first
In FIG. 9, the right half shows the state before processing, and the left half shows the state after processing.
The molding device is roughly divided into an inner die 110 and a punch 1.
11 and an outer die 112. Inner die 11
0 supports the cup original blank 113. Further, the punch 111 is used for the cup original blank 11.
It has an inner wall forming surface 115 having a taper to form an inner wall of 3. Moreover, the outer die 112 is
When the punch 111 is pushed in, this punch 11
1 and sliding together along the axial direction of the inner die 110, the inner die 110 has an outer wall forming surface 117 consisting of a tapered hole for forming the outer wall of the cup-shaped blank 116. . Furthermore, the outer wall molding surface 11 of the outer die 112
The taper angle of No. 7 is slightly smaller than the taper angle of the inner wall forming surface 115 of the punch 111 with respect to the central axis of the blank.

Then, by backward extruding the cup original blank 113 using the forming apparatus, a cup-shaped blank 116 is formed.

According to this, the backward extrusion process becomes easy, which is quite effective, and defects such as the aforementioned splits and cracks can be prevented. However, because it involves a large increase in frictional force between the material and the tool,
It is difficult to avoid many restrictions, such as the appropriate method of preventing seizure, selection of materials, selection of lubrication, and selection of cross-sectional shrinkage ratio.

[Problems to be Solved by the Invention] As mentioned above, conventional flare wall forming tends to cause defects such as splits and cracks in the product, and the frictional force generated between the material and the tool is large. However, it was extremely difficult to form the flared wall, and there were problems in that stress cracking was likely to occur and tool life was short.

Therefore, the present invention makes it difficult to produce defects such as splits and cracks in the product, reduces the frictional force generated between the material and the tool, facilitates the formation of flared walls, prevents stress cracking, and improves the tool quality. An object of the present invention is to provide a flare wall forming device that can be used for a long period of time.

[Means for Solving the Problems] The flare wall forming apparatus of the present invention which solves the above problems comprises: expanding and deforming a blank cylindrical wall in the radial direction to form a flare wall having a tapered hole to be formed on the inner periphery. A flare wall forming apparatus for forming a shape, comprising: a punch having a tapered surface for forming a tapered hole in the inner periphery of the flare wall; and a punch for supporting the blank and forming an outer wall of the flare wall when the punch is pressed. a die having a tapered inner wall, the tapered inner wall of the die partially supports the outer wall of the flared wall to prevent expansion deformation of that portion, thereby causing a compressive deformation portion in the radial direction in the flared wall. A pressurizing section is formed for forming.

[Operation] According to the above means, as the punch advances with respect to the die, a tapered hole is formed on the inner periphery of the flare wall, and a compressively deformed portion is formed on the flare wall by the pressurizing part of the punch and the die. , since the reduced wall thickness at that portion flows in the circumferential direction, a flared wall is easily formed.

[Example] An example of the present invention will be described below with reference to FIGS. 1 to 5.

In this example, as shown in FIGS. 2 to 5, a cylindrical wall 2 of a cup original blank 1 consisting of a cylindrical cup shown in the right half of each figure is formed by molding, as shown in the left half of each figure. A cup forming blank 4 which is expanded and deformed is formed on a flared wall 5. 2 is a perspective view of the blank, FIG. 3 is a plan view thereof, FIG. 4 is a cross-sectional view taken along the line -- in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line -- in FIG. 3.

The cylindrical wall 2 of the cup original blank 1 has an inner diameter
It is formed by RI, outer diameter RO, and height h.

The flared wall 5 of the cup-forming blank 4 has a tapered hole 6, and has four compressive deformation portions 7 along its axial direction, that is, the vertical direction, in a radial manner. That is, the flared wall 5 has a slit groove 10 formed by the compressive deformation portion 7 on its outer wall. Note that the flare wall 5 is
A minimum inner diameter (tapered hole diameter) that is the same as the inner diameter RI of the cylindrical wall 2, a minimum outer diameter that is the same as its outer diameter RO, a maximum inner diameter RIa that is the same as its height h and larger than the inner diameter RI, and It is formed with a maximum outer diameter ROa that is larger than the outer diameter RO. Further, the portion between the compression deformation portions 7 of the flared wall 5 is referred to as an expansion portion 11.

Next, the molding device will be explained with reference to FIG. 1, which shows a cross-sectional view of the molding device. In FIG. 1, the right half shows the state before the molding device is activated, and the left half shows the state after the molding device is activated.

The molding device is composed of a punch 13 and a die 14. The punch 13 has a tapered surface 1 for forming the tapered hole 6 of the cup forming blank 4.
6 at the lower end. Although not shown, this punch 13 is attached to a ram of a press machine.

Further, the die 14 is used for the cup original shape blank 1.
It has a tapered inner wall 17 for supporting the punch 13 and forming an outer wall of the flare wall 5 when the punch 13 is pushed in, that is, when it moves downward. The tapered inner wall 17 is provided with a process that partially supports the outer wall and prevents expansion deformation of that portion during molding of the flared wall 5, thereby forming a compressive deformation portion 7 in the radial direction in the flared wall 5. A pressure portion 18 is formed. The wall surface of this pressurizing part 18 is formed to have an inner diameter equal to the outer diameter RO of the cup original blank 1 in its axial direction. Furthermore, die 14
is equipped with an extrusion pin 20 at its center. Although not shown, the die 14 is installed on the table of the press.

In the above-described forming apparatus, after the cup original blank 1 is inserted into the die 14, the punch 13 is lowered to expand the cylindrical wall 2 of the cup original blank 1 into the flared wall 5, and the cup forming blank 4 is molded. be done.

During this molding, the punch 13 against the die 14
As the process progresses, the inner wall of the cylindrical wall 2 of the cup original blank 1 is expanded into the tapered hole 6 by the tapered surface 16 of the punch 13, and the outer wall of a part of the cylindrical wall 2 is expanded by the tapered surface 16 of the punch 13. By being compressed and deformed while being supported by the pressurizing part 18, the reduced wall thickness of that part flows in the circumferential direction, and the other parts are formed by the tapered inner wall 17 of the die 14 and the tapered surface 16 of the punch 13. As a result, the cylindrical wall 2 is expanded as the expanded portion 11 without changing the thickness of the cylindrical wall 2, and as a result, the cylindrical wall 2 is easily formed as the flared wall 5.

Next, the deformation process of the flared wall 5 accompanying the forming will be explained with reference to FIG. 3. This description will be made within the range of the center line y of the expansion part 11 and the center line z of the compressive deformation part 7. Note that points B, A, and G in FIG. 3 are points on the circumferential line of the inner diameter RI of the cylindrical wall 2 of the cup original blank 1, and points C, D,
H is a point on the circumferential line of the outer diameter RO of the cylindrical wall 2. Points B1, A1, F, and E are on the circumferential line of the maximum inner diameter RIa of the flared wall 5 of the cup-formed blank 4, and points C1 and D1 are on the circumferential line of the maximum outer diameter ROa of the flared wall 5. This is the point.

At the compression deformation portion 7 at the open end face of the flared wall 5 of the cup forming blank 4, the punch 1
3, points A and G are displaced to points F and E, but points D and H are not displaced. Therefore, wall areas A, G, E, F are compressed into wall areas F, E, H, D. In addition, in the expanded portion 11, the wall areas B, A, D, and C, which have no wall thickness variation, move in parallel along the line y to the wall areas B1, A1, D1, and C1. The fluctuation is almost 0.

In other words, the areas A, G, E, and F that are compressed become the areas B1, A1, and
The spaces A1, F, D, created when D1 and C1 become,
This will satisfy D1. Therefore, the wall areas B, G, H, C before processing are the wall areas B1, E, H, after processing.
Since D, D1, and C1 are almost the same, the displacement of the flare wall 5 due to machining in the axial direction can be set to zero.

In this way, since the cylindrical wall 2 is formed into the flared wall 5 with almost zero fluctuation in the longitudinal direction, the displacement method in each annular cross section of the cylindrical wall 2 is the same as that of the flared wall 5.
The deformation is the same as described above in each cross section of the taper, and the deformation is large on the large diameter side of the taper, small on the small diameter side, and zero at the minimum diameter end.

As is clear from the above description, when designing the die 2, the wall areas A, G, E, and F are the wall areas.
A1, F, D, and D1 should be determined to be equal to each other. Naturally, the shape of the slit groove 10 of the flare wall 5 should be linear in proportion to the inner diameter of the taper, and its depth should be determined at the small diameter end of the taper. The flow rate of the slit groove 10 is the same as the height h of the flared wall 5.

Further, the flare wall forming apparatus described above is not limited to the cup original blank 1, as shown in FIG.
It is also possible to obtain the cup-forming blank 4 by molding a bar blank 22 made of a cut bar. In FIG. 6, the right half shows the state before the molding device is activated, and the left half shows the state after the molding device is activated.

In the case of forming the bar blank 22, the upward flow of the material due to backward extrusion is sequentially compressed on the inner circumferential surface of the die 14 and extends in the circumferential direction, and this effect causes the gap between the die 14 and the material to Relative flow friction can be significantly reduced.

In addition to the cup original blank 1 and the bar blank 22, the present invention can also be applied to the case where only the flared wall 5 is formed using a simple cylindrical material as a blank.

In addition, in the flare wall forming apparatus of the above embodiment, in order to simplify the explanation, the pressurizing parts 18 of the die 14 were set at four places, but in reality, the number of pressurizing parts 18 is determined so that the material flows effectively, e.g. As shown in FIGS. 7 and 8, by forming about 12 die 14
The frictional force between the blank and the blank is significantly reduced, making it easier to form a flared wall.

Further, the shape of the pressurizing part 18 of the die 14 is not limited to the example, and other shapes,
For example, it may be triangular, wave-shaped, tooth-shaped, etc. Also,
There is no problem even if the number of pressurizing parts 18 formed is increased or decreased.

In addition, in the embodiment, the pressurizing part 18 of the die 14
Although the wall surface is approximately the same as the outer diameter RO of the cylindrical wall 2 of the cup original blank 1, depending on the properties of the material of the blank, it may be slightly larger in a tapered manner as it approaches the upper edge.

Further, the maximum outer diameter ROa of the flared wall 5 of the cup-forming blank 4 is desirably set to ROa = RO - RI + RIa, but it may be increased depending on the properties of the material of the blank.

Moreover, if the above-mentioned embodiment is applied, the 9th and 1st
A universal joint joint cup 24 as shown in FIG. 0 can be easily formed. In FIGS. 9 and 10, the left half shows the blank before molding, and the right half shows the blank after molding. In the figures, the same reference numerals are given to the same parts as in the embodiment, and the explanation thereof will be omitted.

When the tapered hole 6 is formed with a gently curved surface like the joint cup 24, shaping the tapered hole 6 during the forging operation often makes the work extremely difficult. It is extremely effective to use the molding apparatus of the invention.

Further, an example of secondary molding of the cup forming blank 4 will be described with reference to FIGS. 11 to 15. In this example, as shown in FIGS. 12 to 15, the flare wall 5 of the cup molding blank 4 shown in the left half of each figure is molded to form the flare wall 5 shown in the right half of each figure. A cup-processed blank 26 which is expanded and deformed on a wall 27 is formed. 12 is a perspective view of the blank, FIG. 13 is a plan view thereof, FIG. 14 is a cross-sectional view taken along the line -- in FIG. 13, and FIG. 15 is a cross-sectional view taken along the line -- in FIG. 13.

Flare large wall 2 of the cup processing blank 26
7 is a minimum inner diameter that is the same as the minimum inner diameter RI of the flare wall 5, a minimum outer diameter that is the same as its minimum outer diameter RO, a maximum outer diameter that is the same as its maximum outer diameter ROa, and a height h.
, and has a maximum inner diameter RIb larger than the maximum inner diameter RIa. That is, the outer shape of the cup-processed blank 26 is the same as that of the cup-formed blank 4, and the maximum inner diameter RIb of the large flare wall 27 is larger than the maximum inner diameter RIa of the flare wall 5 of the cup-formed blank 4.
It has a large degree of taper. Therefore, the flare large wall 27 has a uniform thickness in the circumferential direction, and the thickness gradually becomes thinner toward the tip.

Next, the forming apparatus for the cup blank 26 will be explained with reference to FIG. 11, which shows a cross-sectional view thereof. In FIG. 11, the left half shows the state before the molding device is activated, and the right half shows the state after the molding device is activated.

The forming device is composed of a punch 30 and a tie 31. The punch 30 has a tapered surface 33 at its lower end for forming the tapered hole 28 of the cup blank 26. This punch 30
is attached to the ram of the press (not shown).

The die 31 also has a tapered inner wall 34 for supporting the cup forming blank 4 and for supporting the outer wall of the flared large wall 27 when the punch 30 is pushed in, that is, when it moves downward. Since this tapered inner wall 34 has the same size as the cup forming blank 4, the forming blank 4 is tightly fitted into the die 31. Note that the die 31 is provided with an extrusion pin 36 at its center. Although not shown, the die 31 is installed on the table of the press.

In the above-described forming apparatus, after the cup forming blank 4 is inserted into the die 31, the punch 30 is lowered, so that the flare wall 5 of the cup forming blank 4 is expanded into the large flare wall 27, and the cup forming blank 26 is expanded. is formed.

During this forming, as the punch 30 descends, the tapered hole 6 of the flared wall 5 of the cup forming blank 4 remains supported by the tapered inner wall 34 of the die 31.
The maximum inner diameter RIa of the flared wall 5 is increased and expanded to the maximum inner diameter RIb at the lowest point of the punch. As a result, the flared wall 5 is formed into the flared large wall 27.

The deformation process of the flared wall 5 accompanying the forming will be explained with reference to FIG. 13. This explanation is
Explanation will be made in the range between the center line y of the expanded portion 11 and the center line z of the compressive deformation portion 7. Note that points B1, E, H, D, D1, and C1 in FIG. 13 are the same points as explained in the deformation process of the flared wall 5 of the cup forming blank 4. Also, points B2 and E1 in the same figure
is a point on the circumferential line of the maximum inner diameter RIb of the flare large wall 27, and point H1 is a point on the circumferential line of the maximum outer diameter ROa.

In the flared wall 5 of the cup forming blank 4, as the punch 30 advances, the areas B1, E, H1, and C1 of the portion constituted by the maximum inner diameter RIa and the maximum outer diameter ROa of the flared wall 5 change to the area B2, E1,
H1, C1, and the area of the compressed area B1, E,
E1 and B2 are the area D of the gap between the slit groove 10 of the molded blank 4 and the tapered inner wall of the die 31;
Fills H, H1, and D1. Therefore, wall area B1,
E, H, D, D1, C1 are wall areas B2, E1, H1,
Transforms into the shape of C1. Therefore, even in this process, almost no frictional force is generated between the tapered inner wall 34 of the die 31 and the material, and it is possible to form the cupped blank 26 with a large degree of taper.

[Effects of the Invention] According to the flare wall forming apparatus of the present invention, as the punch advances relative to the die, a tapered hole is formed on the inner periphery of the flare wall, and the pressure part of the punch and the die forms a tapered hole in the flare wall. A compressively deformed part is formed in the area, and the reduced wall thickness at that part flows in the circumferential direction, so that the flared wall is formed smoothly, making it difficult for defects such as splits and cracks to occur in the product, and improving the quality of the material. The frictional force generated between the tool and the tool is reduced, making it easier to form the flared wall, preventing stress cracking, and allowing the tool to be used for a long time.

The parts molded using the flare wall molding apparatus of the present invention include coupling parts, joint housings, etc., and the range of applications of the molding apparatus is wide.

[Brief explanation of drawings]

1 to 5 show an embodiment of the present invention,
Figure 1 is a sectional view of the flare wall forming device showing the right half before operation and the left half after operation, and Figure 2 shows the cup original blank in the right half and its left side. FIG. 3 is a plan view of the blank shown in FIG. 2, and FIG.
The figure is a cross-sectional view taken along the line -- in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line -- in FIG. FIG. 6 shows another example of forming a blank, and is a sectional view of the flare wall forming apparatus showing the right half before operation and the left half after operation. 7 and 8 show practical examples of the die, with FIG. 7 being a plan view and FIG. 8 being a half-sectional front view. Figures 9 and 10 show the joint cup of the universal joint, and Figure 9 is a perspective view showing the left half of the blank after molding and the right half of the blank after molding.
FIG. 0 is a cross-sectional view of the blank of FIG. 9. 11th
Figures 15 to 15 show an example of secondary molding of a cup forming blank, and Figure 11 is a sectional view of the molding device showing the left half before operation and the right half after operation; Fig. 12 is a perspective view showing the cup forming blank in the left half and the cup processing blank in the right half, Fig. 13 is a plan view of the blank in Fig. 12, and Fig. 14 is a line taken along the - line in Fig. 13. cross section,
FIG. 15 is a sectional view taken along the - line in FIG. 13. Figures 16 to 19 show conventional examples.
Figure 6 is a perspective view of the taper cup product, No. 17, 1
FIG. 8 is a side view of the defective product, and FIG. 19 is a sectional view of the molding device showing the right half before operation and the left half after operation. DESCRIPTION OF SYMBOLS 1...Cup original shape blank, 4...Cup forming blank, 5...Flare wall, 6...Tapered hole, 7...Compression deformation part, 13...Punch, 14...
...Die, 16... Tapered surface, 17... Tapered inner wall, 18... Pressure section.

Claims (1)

[Scope of Claims] 1. A flare wall forming apparatus that expands and deforms a blank cylindrical wall in the radial direction to form a flare wall having a tapered hole to be formed on the inner circumference, comprising: a taper on the inner circumference of the flare wall; a punch having a tapered surface for forming a hole; and a die having a tapered inner wall for supporting the blank and forming an outer wall of the flared wall when the punch is pushed in; A flare wall forming device, wherein a pressure section is formed for forming a radially compressive deformation portion in the flare wall by partially supporting the outer wall of the flare wall and preventing expansion deformation of that portion.