JPH01178324A - Method and die for molding pin corner by opposed liquid pressure molding - Google Patents

Abstract

PURPOSE:To form roundness in a parting part without generating cracks by elongating the neighborhood of a parting part as an upper die is being lowered, drawing a work reversely increasing liquid pressure in a lower die shell and forming a roundness small in radius at the parting part of the work. CONSTITUTION:The work 26 mounted on the upper surface of the lower die shell 24 full of liquid 23 is held between blank holders 28, 30 and when the upper die 22 is lowered, a flexible guide punch 32, too, provided on the side wall of the upper die 22 is lowered. The work 26 is pressurized by the lower end part of the guide punch 32 downward to elongate the neighborhood of the parting part 26a. When liquid pressure is increased as the upper die is lowered further, the work 26 is drawn reversely, the parting part 26a becomes smoother and small roundnesses hard to crack and small in radius are formed at parting parts. Since small roundnesses can be formed in one die, it is possible to present a molding die which does not require bending operation in forming roundness small in radius and excells in work efficiency.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention performs press molding using an upper die molded into a product shape and a liquid filled in a lower die shell provided below the workpiece to be formed. The present invention relates to opposed hydraulic forming, and relates to a pin angle forming method using opposed hydraulic forming to form a rounded part with a small radius on the parting part of a workpiece, and a mold thereof.

(Prior art) Conventionally, when forming metal panels such as vehicle parts,
A facing hydraulic forming apparatus as shown in Japanese Utility Model Application Laid-Open No. 62-92020, which is advantageous in terms of production period and cost, may be used.

As shown in Fig. 5, this device is provided with an upper die punch 2 for forming a metal panel l along the product shape at the upper part, and a liquid such as water or the like is placed inside so as to face the upper die punch 2 at the lower part. 3 and is provided with a lower mold shell 5 in which pins 4 are locally arranged. When forming the metal panel 1, the end of the metal panel 1 is held between the lower blank holder 6 attached to the lower die shell 5 and the upper blank holder 8 attached to the upper table 7, and the upper die punch 2 When pressed, the metal panel 1 is formed as described later.

That is, when the sandwiched metal panel 1 is pushed in from above with the upper mold 2, the inside of the lower mold shell 5 is sealed by the metal panel 1, the volume of the internal liquid 3 decreases, and hydraulic pressure is generated. The metal panel 1 is formed along the pressurized surface of the upper mold. When forming a roundness 9 with a small radius as shown in FIG. 6 in the parting part 1a of the metal panel 1 to be formed, this device first draws and stretches a roundness 10 with a large radius, and then this metal panel 1 was taken out from the equipment and bent to form a rounded part 9 with a small radius. This is done without stretching the parting part 1a of the metal panel 1.
When the roundness 9 with a small radius is drawn and formed, the elongation and slippage of the metal panel 1 becomes poor, resulting in a formed metal panel l.
This is because cracks occur at the rounded portion 9 with a small radius. Therefore, conventionally it has been impossible to form a round shape with a small radius using one drawing die.

In addition, the lower mold is locally disposed within the lower mold shell, and liquid discharge holes are bored with a predetermined density distribution.
2-25014).

(Problems to be Solved by the Invention) However, in the conventional opposed hydraulic forming mold described above, when forming a rounded part with a small radius at the parting part of a metal panel,
Since the process was carried out in multiple steps, there were problems in that each task was complicated and efficiency was extremely low. Therefore, there has been a desire for an apparatus that can form a rounded part with a small radius in the parting part of a metal panel using a single mold.

Furthermore, the hydroforming apparatus disclosed in Japanese Utility Model Application Publication No. 62-25014 does not solve the conventional technology.

The present invention has been made in view of the above problems, and when forming a metal panel, the pin angle is formed by opposing hydraulic pressure forming, which stretches the parting part of the metal panel and forms a small radius roundness that does not cause cracks in the parting part. The purpose of the present invention is to provide a molding method and a mold thereof.

(Means for Solving the Problems) In order to solve the above-mentioned problems, a pin corner forming method using opposed hydraulic forming according to the present invention includes disposing a workpiece 26 on the upper surface of a lower mold shell 24 filled with a liquid 23. Holder 28.30
While lowering the upper mold 22 from above, stretch the workpiece 26 near the parting part, and then lower the lower mold shell 2.
While increasing the hydraulic pressure in the workpiece 2G, the upper die 22 is further lowered to perform reverse drawing on the workpiece 26, and the parting portion 28 of the workpiece 2G is
It is characterized by forming a roundness 41 with a small radius on the edge a.

Further, the pin square forming die by opposed hydraulic forming according to the present invention is provided with a die 22 for a press machine that is formed into a product shape,
A lower mold shell 24 is filled with liquid 23 below the upper mold 22 and has pins 27 locally arranged at predetermined locations inside.
A holder 28.30 is provided facing the upper mold 22 and holds the work 26 between the lower mold shell 24 and the upper mold 22. Therefore, a telescopic guide punch 32 is provided to give downward elongation to the workpiece 26.

(Function) In the pin angle forming method using opposed hydraulic forming with the above configuration, the parting portion 28a of the workpiece 26 placed on the L surface of the lower die shell 24 is used.
The upper mold 22 is lowered while stretching the vicinity, and the upper mold 22 is lowered! 12
1. If the hydraulic pressure is increased and the workpiece 26 is reversely throttled by the hydraulic pressure when the bottom dead center is near the bottom dead center of 2. Work 26
The sliding of the parting part 28a is improved, and the parting part can be formed into a rounded part with a small radius without cracks.

In addition, in the pin square forming mold using opposed hydraulic forming, when the workpiece 26 is first placed on the upper part of the lower mold shell 24 and the upper mold 22 is lowered, a telescopic pin provided on the side wall of the upper mold 22 is attached. The guide punch 32 also descends, and the guide punch 3
At the lower end of 2, press the workpiece 26 downward and stretch it (the pressure of the guide punch at this time is greater than the pressure of the liquid), then increase the liquid pressure without lowering the upper mold 22 further. Then, the workpiece 2B is reverse drawn, the workpiece becomes smoother, and a roundness 41 with a small radius is formed at the parting part of the workpiece.

(Example) Next, an example of the present invention will be described based on the drawings. 1st
In the figure, numeral 21 is a mold for performing opposed hydraulic molding, and shows the completed state of molding.

The upper part of the mold 21 is an upper punch 22 which is an upper mold for a press machine that is molded into a product shape.

A lower mold shell 24 filled with a liquid 23 such as water is provided at a position below the upper mold punch 22 and facing the upper mold punch 22 and placed fa on a bolster table 25 . Further, inside the lower mold shell 24, a molding surface 2 of the upper mold punch 22 is provided.
A pin, that is, a local lower die 27 having a stepped portion 27a for machining the work 28 into an accurate shape is provided along the pin 2a.

Also, on the frame of the lower shell 24 is a lower blank holder 28.
is provided, and an outer table 28 on the outer periphery of the upper die punch 22 is provided.
An upper blank holder 30 is attached to the.

This lower blank holder 28 and upper blank holder 3
0 is for holding and holding the workpiece 26.

Further, on the side wall of the upper punch 22, as the upper punch 22 descends, a rounded portion 3 with a large radius is formed downward at the parting portion 28a of the workpiece 28! Two telescopic guide punches 32 are slidably provided on the left and right sides to form a shape (see FIG. 2), that is, to provide downward elongation.

The guide punch 32 is attached to the tip of a rod 35 of a cylinder device 34 for compressed air, nitrogen gas, etc., which is fixed to a bar 33 provided on the upper part of the upper die punch 22. The guide punch 32 is always urged downward, and the tip of the guide punch 32 is flush with the end of the molding surface 22ai of the upper die punch 22.

A pump unit 36 is connected to the inside of the lower mold shell 24 so that the internal liquid can be supplied and discharged to adjust the liquid pressure. Also, 37 is an 0 ring, 38 and 39
is a sealing material that prevents liquid leakage during molding and prevents a drop in liquid pressure. Reference numeral 40 denotes an inner table provided at the front of the upper die punch 22.

Next, a pin angle forming method using opposed hydraulic forming having the above structure will be explained using FIGS. 2 to 4. For convenience, the explanation will be made using the left part of the drawing. First, a metal panel, that is, a workpiece 28 is placed on a lower mold shell 24 filled with a liquid 23 and provided with a local lower mold 27, and the workpiece 26 is held between a lower blank holder 28 and an upper blank holder 30 (
The broken line in Figure 1 shows the state at that time).

Subsequently, the upper die punch 22 is lowered via the inner table 40 and the bar 33 by the operation of a main ram (not shown) from above, and presses the workpiece 2B into the lower die shell 24. At this time, the guide punch 32 attached to the side wall of the upper die punch 22 presses the end of the workpiece 28 from above to form a downward rounded radius 31 with a large radius near the parting part 28a of the workpiece 26. 26 parting section 211
Stretch the area near 1a downward (see Figure 2). The pressure of the liquid 23 at this time is set to be lower than the pressing force of a nitrogen gas cylinder or the like that urges the guide punch 32.

Next, while lowering the upper punch 22, the liquid dome 24
When the hydraulic pressure inside is increased, reverse throttling is performed on the workpiece 26 (see FIG. 3). Therefore, the upper die punch 22 and the local lower die 2
7, the stretched work 26 is pushed into the lower local mold 27 from one side, so that the work 22 has a small radius roundness 41 with improved slippage and no cracks. The parting portion 211ia is molded (see FIG. 4).

(Effects of the Invention) As explained in detail above, the pin angle forming method using opposed hydraulic forming according to the present invention has a process of stretching the vicinity of the parting part of the workpiece and then performing reverse drawing to create a small part in the parting part of the workpiece. A rounded radius can be formed. Therefore, cracks do not occur in the roundness of the parting part of the workpiece due to this forming.

The pin square forming die using opposed hydraulic forming according to the present invention has a telescopic guy punch provided on the side wall of the upper die to give the workpiece a downward elongation. It is possible to form a round shape with a small radius.

In addition, since the molding can be performed within one mold, the bending step of rounding with a small radius, which is conventionally performed, can be omitted, and an excellent molding mold with high working efficiency can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view of an opposed hydraulic mold according to an embodiment of the present invention, and FIG. 2 is a left-hand guide punch showing the guide punch of the mold shown in FIG. 1 stretching the workpiece downward. 3 is a sectional front view of the vicinity of the left guide punch showing the workpiece being reverse drawn by the mold shown in FIG. 1, and FIG. 4 is a front view of the workpiece being drawn by the mold shown in FIG. FIG. 5 is a cross-sectional front view of the vicinity of the left guide punch showing the drawing process, FIG. 5 is a cross-sectional front view of a conventional opposed hydraulic forming die, and FIG. 6 is a front view of the bent workpiece. 21... Opposing hydraulic mold 22... Upper die (upper die punch) 23... 4 liquids 24... Lower die shell 26... Workpiece 28a... Parting part 27.
...Pin (lower local mold) 28, 30...Holder (lower blank holder, upper blank holder)

Claims (2)

[Claims] (1) Place the workpiece on the upper surface of the lower mold shell filled with liquid, hold it with a holder, and lower the upper mold from above.
The method is characterized in that the vicinity of the parting part of the workpiece is stretched, and then, while increasing the hydraulic pressure in the lower die shell, the upper mold is further lowered to apply reverse drawing to the workpiece, forming a roundness with a small radius in the parting part of the workpiece. Pin angle forming method using opposed hydraulic pressure forming. (2) An upper mold for a press machine formed into a product shape is provided, and a lower mold shell, which is filled with liquid below the upper mold and has pins arranged at predetermined locations inside, is placed opposite to the upper mold. a holder for holding the workpiece between the lower mold shell and the upper mold; and a retractable guide provided on the side wall of the upper mold to cause the workpiece to stretch downward as the upper mold descends. A pin square forming mold using opposed hydraulic pressure forming, which is characterized by the provision of a punch.