JPH04228231A - Pressing die - Google Patents

Abstract

PURPOSE:To eliminate or reduce grinding work, to shorten manufacturing time, to reduce manufacturing cost and further, to produce a pressing die improved in pressing workability. CONSTITUTION:Manufacture forming face 1a, 2a and holding face 1b, 2b continuously formed to the manufacture forming face 1a, 2a, are made to rough face- state formed with cutting trace by cutting work. The grinding work is eliminated or reduced, and further, contact between the work and the pressing die, becomes point or linear contact from surface contact, and by reducing friction resistance, spreading and slippage in the work at the time of press-forming are improved, and the press-formability is improved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an automobile outer panel,
This invention relates to a press mold for press-forming workpieces made of steel plates such as inner panels.

0002

2. Description of the Related Art In order to obtain a press-formed product having a convex portion, a partial convex portion 1 is provided on a lower mold 12 as shown in FIG.
2c, the work w is set on the second holding surface 12b, and the concave portion 11 provided opposite to the convex portion 12c is
The upper mold 11 having the first product forming surface 11a having a shape of 1.c is lowered, and the workpiece w is lowered by the first pressing surface 11b formed on the upper mold 11 and the second pressing surface 12b formed on the lower mold 12.
The second product molding surface 1 of the lower mold 12 is held between the peripheral edge wa of the
2a to the first product forming surface 1 of the upper die 11 via the workpiece w.
This is done by fitting it into 1a.

These first and second product forming surfaces 11a, 1
2a, the first and second holding surfaces 11b, 12b, the partial concave portion 11c and the convex portion 12c are cut into a press mold using a ball end mill or a tipped taper cutter using a copy milling machine or an NC milling machine. Processing is performed, and the cutting marks called cusps that occur on the product molding surface and presser surface due to cutting are removed by polishing using electric and chemical methods such as electrical discharge machining, electrolytic machining, and ultrasonic polishing, and power tools. The first and second product forming surfaces 11a and 12a, the partial concave portion 11c, and the partial convex portion 12c are finished, and the clearance between the first and second product forming surfaces 11a and 12a is adjusted. There is. Grinded first and second product forming surfaces 11a, 12a, concave portion 11c, convex portion 12c
Further, the first and second holding surfaces 11b and 12b are plated with hard chrome to improve wear resistance, if necessary (see Japanese Utility Model Application No. 150837/1983).

0004

[Problems to be Solved by the Invention] According to the conventional press mold, in order to polish the product forming surface and presser surface of the press mold,
This requires a large number of man-hours and a long manufacturing period. During the press forming process, approximately 5mm above the bottom dead center
The work is often stretched locally at the front and back, causing the work to break. As a countermeasure to this, the press die near the area where the breakage occurred was reground and the clearance between the upper and lower die was adjusted. However, if the breakage cannot be resolved even after taking these measures, there may be problems such as the necessity to change the product shape.

Therefore, an object of the present invention is to eliminate or reduce the polishing process, shorten the manufacturing period and reduce the manufacturing cost, and furthermore, by changing the surface shape of the product forming surface and pressing surface of the press die, the workpiece can be improved. It is an object of the present invention to provide a press die that allows elongation over a wide range and improves press formability.

[0006]

[Means for Solving the Problems] The press mold of the present invention that achieves the above objects includes a first product forming surface and a first product forming surface formed on the outer periphery of the first product forming surface in a continuous manner with the first product forming surface. an upper die having a first presser surface, a second presser surface that works together with the first presser surface to clamp the periphery of the workpiece, and a first product forming surface that is formed continuously with the second presser surface; and a lower die having a second product forming surface that press-forms a workpiece in cooperation with the first product forming surface, the first pressing surface, the second product forming surface, and the second product forming surface. At least one of the second pressing surfaces is formed into a rough surface by cutting marks caused by cutting, and the upper die having the first product forming surface and the first product forming surface are in contact with each other. a lower die having a second product forming surface for press forming a workpiece; a convex portion formed within one of the first and second product forming surfaces;
In a press die having a concave portion formed in the other product forming surface and press-forming the convex portion on the workpiece in cooperation with the convex portion, the convex portion, the concave portion, and the convex shape of the product forming surface. At least one of the circumferential edge portion of the concave portion and the circumferential edge portion of the concave portion of the product molding surface is formed into a rough surface shape due to cutting marks caused by cutting.

[0007]

[Function] By making the product molding surface, convex portions, concave portions, pressing surfaces, etc. within the product molding surface rough, formed by cutting marks from cutting, the polishing process, which requires a large amount of man-hours, can be reduced. Since it will be abolished, the production period will be significantly shortened,
Manufacturing costs can be reduced, and the contact between the workpiece and the press mold changes from surface contact to point or line contact, reducing frictional resistance.
Local elongation of the workpiece during press forming is alleviated, and sliding on the pressing surface is improved, resulting in improved drawing workability.

[0008]

[Embodiment] An embodiment of the press mold of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view showing the main parts of the press mold of this embodiment. The upper mold 1 has a first product molding surface 1a that is curved in a convex manner, and a first pressing surface 1b that is formed continuously on the outer periphery of the first product molding surface 1a. A concave portion 1c that is concave upward is formed in the product molding surface 1a.

On the other hand, the lower mold 2 has a second product molding surface 2a which is curved concavely upward so as to fit into the first product molding surface 1a formed on the upper mold 1 with the work w interposed therebetween; A second presser surface 2b is provided on the outer periphery of the second product molding surface 2a continuously with the second product molding surface 2a, and the first product molding of the upper mold 1 is carried out within the second product molding surface 2a. It is composed of a convex portion 2c that fits into a concave portion 1c formed on the surface 1a to form a convex portion on the workpiece w.

[0011] A first product molding surface 1a formed on the upper mold 1;
The first holding surface 1b, the concave portion 1c, the second product forming surface 2a, the second holding surface 2b, and the convex portion 2c of the lower die 2 are formed by cutting the cutting edge with a cutting edge radius using a copy milling machine, an NC milling machine, etc. The pick feed is shaped by cutting 2 mm using a ball end cutter with a radius of 25 mm, and the surface thereof is formed into a rough surface with unevenness due to cutting marks 3 called cusps, as shown in the enlarged perspective view in FIG. . Furthermore, these surfaces are plated with hard chrome plating 4 of, for example, 20 to 30 microns, as shown in FIG. 3, in order to improve wear resistance, if necessary.

[0012] In order to perform press forming using the press die constructed as described above, the upper die 1 is raised to the top dead center position, and the workpiece w is placed in the lower die 2 as shown by the dashed line in FIG. The product is placed and set on the formed second product molding surface 1a, and the upper mold 1 is lowered to form the first presser surface 1b formed on the upper mold 1 and the second presser surface 2b formed on the lower mold 2. While holding the end of the workpiece w by the cooperation of The work w is press-molded between the concave portion 1c and the convex portion 2c formed in the second product forming surface 2a.

At this time, the first and second product forming surfaces 1a,
2a, first and second pressing surfaces 1b, 2b, and concave portion 1
c. The convex portion 2c has a rough surface formed by the cutting traces 3 as described above, so that the contact with the workpiece w is a point contact or a line contact, so that the workpiece w and product forming are not easily formed. The sliding resistance between the surfaces 1a and 2a, the holding surfaces 1b and 2b, the concave portion 1c, and the convex portion 2c is small, and in the case of a lower die polished to a smooth surface as in the conventional case, as shown in FIG. 6(a). As shown in FIG. 6(b), no elongation of the workpiece w is observed over almost the entire width a of the product forming surface 2a, whereas in this example, as shown in FIG. By elongating the workpiece w only in a narrow range a on the forming surface 2a, and therefore over almost the entire width, locally concentrated elongation is alleviated and press formability is improved.

Since elongation of the workpiece w between the holding surfaces 1b and 2b is also allowed, the sliding is further improved and press forming becomes better.

Furthermore, in the above embodiment, the rough surface was formed by cutting marks, but as shown in FIG. By polishing the top part 3a leaving 5 to 10 microns from the bottom of the cutting mark and processing the top surface flat, it improves the contact with the workpiece w and prevents the occurrence of scratches due to contact between the workpiece w and the top part 3a. can do. Furthermore, if necessary, hard chrome plating 4 having a thickness of 20 to 30 microns can be applied to these surfaces as shown in FIG. 5 in order to improve wear resistance.

In the above explanation, the product forming surfaces 1a, 2a, pressing surfaces 1b, 2b, concave portions 1c, and convex portions 2c of the upper and lower molds have been roughened by cutting, but the product shape, material, etc. In consideration of
It is also possible to form a rough surface by cutting only on the convex portion 2c formed on the lower die 2 and the peripheral portion 2d of the convex portion 2c on the second product molding surface 2a. Furthermore, an embodiment has been described in which a concave portion is provided in the first product molding surface and a convex portion is provided in the second product molding surface. It is also possible to provide a concave portion within the product molding surface of No. 2, and it is also possible to provide a plurality of convex portions and concave portions.

[0017]

Effects of the Invention According to the present invention, the convex portions and concave portions formed on the product forming surface, presser surface, and product forming surface of a press mold are formed into a rough surface by grinding, thereby making it possible to overcome the conventional problems. The polishing process, which required man-hours, can be abolished or significantly reduced, shortening the production period and reducing production costs.Furthermore, the contact surface of the press mold with the workpiece during press forming can be made into point or line contact. By doing so, it is possible to improve the sliding of the workpiece during molding, improve press formability, and reduce breakage that occurs in press molded products and correction grinding of press molds.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts showing an embodiment of a press mold of the present invention.

FIG. 2 is an enlarged perspective view of the main parts of the press mold.

FIG. 3 is an enlarged perspective view of a main part of a press mold according to another embodiment.

FIG. 4 is an enlarged perspective view of a main part of a press die according to still another embodiment.

FIG. 5 is an enlarged perspective view of a main part of a press mold according to still another embodiment.

FIG. 6 is a diagram illustrating a comparison between this embodiment and a conventional example.

FIG. 7 is a sectional view of a main part of a conventional press mold.

[Explanation of symbols]

1 Upper mold 1a First product molding surface 1b Second presser surface 1c Concave part 1d Concave periphery 2 Lower mold 2a Second product molding surface 2b Second presser surface 2c Convex part 2d Convex periphery 3 Cutting marks 3a Top w Work

Claims (6)

[Claims] Claim 1: An upper mold having a first product forming surface and a first holding surface formed continuously with the first product forming surface on the outer periphery of the first product forming surface, and the first holding surface. a second product forming surface that is formed continuously with the second holding surface and that press-forms the workpiece in cooperation with the first product forming surface; In the press die, at least one of the first product forming surface, the first pressing surface, the second product forming surface, and the second pressing surface is cut by cutting marks caused by cutting. A press mold characterized by a rough surface. 2. The press mold according to claim 1, wherein the tops of the convex portions of the irregularities forming the rough surface are ground. 3. The press die according to claim 2, wherein the tops of the convex portions of the irregularities forming the rough surface are ground by leaving 5 to 10 μm from the bottoms of the concave portions. 4. An upper die having a first product forming surface, a lower die having a second product forming surface that press-forms a workpiece in cooperation with the first product forming surface, and first and second product forming surfaces. A press having a convex part formed in one of the product forming surfaces, and a concave part formed in the other product forming surface, which cooperates with the convex part to press-form the convex part on the workpiece. In the mold,
At least one of the convex part, the concave part, the peripheral part of the convex part of the product molding surface, and the peripheral part of the concave part of the product molding surface is formed into a rough surface shape by cutting marks caused by cutting. Press type. 5. The press mold according to claim 4, wherein the tops of the convex portions of the irregularities forming the rough surface are ground. 6. The press mold according to claim 5, wherein the tops of the convex portions of the irregularities forming the rough surface are ground by leaving 5 to 10 μm from the bottoms of the concave portions.