JP5941369B2 - Hydraulic molding method and hydraulic molding apparatus - Google Patents

Description

  The present invention relates to a hydraulic forming method and a hydraulic forming apparatus capable of forming panel parts such as automobiles and home appliances with high quality by using liquid pressure in the process of drawing a plate-like blank such as a thin steel plate. About.

  Recently, especially in the automobile industry, in response to a strong demand for weight reduction of the vehicle body due to environmental problems, materials used for panel parts have been reduced in thickness and strength. Processing of this panel part is often performed by low-cost press molding, but there is a problem that cracks and wrinkles are likely to occur in the material (blank) in press molding using a thinned or high-strength material. .

  Therefore, conventionally, a counter hydraulic forming method using hydraulic pressure is known as a drawing forming method capable of suppressing the occurrence of cracks and wrinkles of such a material.

  This type of counter hydraulic forming method is described in, for example, Patent Document 1, and as shown in FIG. 12, for example, a die (lower mold) 1 having a liquid tank 1a that is open on the upper surface and is filled with a liquid. And a hydraulic pressure adjusting mechanism 4 for adjusting the pressure of the liquid filled in the liquid tank 1a according to the position of the punch (upper mold) 3 that moves up and down by the hydraulic cylinder 2, and a blank holder 5 that moves up and down by the actuator. While pressing the peripheral edge 6a of the plate blank 6 between the die 1 and holding the mold clamped, the punch 3 is lowered with respect to the blank holder 5 to push the blank 6 toward the liquid tank 1a. This is a processing method in which the blank 6 is formed by plastic deformation of the blank 6 along the product-shaped punch 3 by applying pressure.

JP 2006-212695 A JP 2009-119476 A

  However, according to the conventional counter hydraulic forming method, the blank holder 5 presses the peripheral edge 6a between the die 1 and the blank 6 is clamped and held at the bottom dead center so that the blank 6 is not displaced or wrinkled. Above, it is necessary to lower the punch 3 with respect to the blank holder 5 and push the blank 6 into the liquid tank 1a. That is, a single-clamped state in which the blank 6 is pressed between the blank holder 5 and the die 1 until the blank 6 is plastically deformed into a product shape along the convex surface portion 3a of the punch 3 by applying a high hydraulic pressure. Therefore, there is a problem that the productivity is lowered by the amount of time necessary to hold the mold clamping state.

  Furthermore, the hydraulic forming apparatus used in the conventional counter hydraulic forming method is additionally provided with a dedicated hydraulic pressure adjusting mechanism 4 for adjusting the pressure of the liquid filled in the liquid tank 1a, and the upper mold has a convex surface portion. It is necessary to use a special hydraulic press machine 3a provided with a special punch 3 having a product shape, and the lower die also needs to use a special die in which a dedicated liquid tank 1a for applying a high hydraulic pressure is recessed. However, since there is no room for using a very general-purpose and inexpensive mechanical press, there is a problem that the capital investment is increased and the production cost is remarkably increased.

  Accordingly, an object of the present invention is to improve productivity by eliminating the need for holding the clamping time of the blank at the time of molding in a hydraulic molding method and a hydraulic molding apparatus, and using a general-purpose mechanical press to reduce equipment investment. It is to reduce the cost.

  Accordingly, in order to solve the above-described problem, the invention described in claim 1 includes, for example, a first concave mold M1 on the fixed side and a concave surface of the first concave mold M1 as in the illustrated embodiment shown below. A first drawing mold M having a convex shape corresponding to the portion 10 and a first convex mold M2 which can be raised and lowered with respect to the concave mold M1, and a second concave mold N1 on the fixed side where the concave surface portion 20 is a product shape. The convex surface portion of the first convex mold M2 in which a gap S is formed between the convex surface portion 25 and the concave surface portion 20 of the second concave mold N1 when the concave mold N1 is movable up and down to the bottom dead center. 15, a second diaphragm mold N configured by a second convex mold N <b> 2 having the same shape is used, and in the first diaphragm mold M, the first convex mold M <b> 2 is positioned at the bottom dead center with respect to the first concave mold M <b> 1. The plate blank B is pressed down to pressurize the plate-like blank B, and an intermediate component in the middle of the product shape in which the liquid reservoir a is formed on the concave side. In the preforming step for processing to the stage of the product x, and in the second drawing mold N, the intermediate molded product x is placed on the concave surface portion 20 of the second concave mold N1 with the gap S facing down. After the part a is set upward and the liquid W is injected into the liquid reservoir part a, the peripheral part of the intermediate molded product x is pressed and clamped, and at the same time, the second convex mold N2 with respect to the second concave mold N1. Is lowered to the bottom dead center, and the intermediate molded product x is pushed into the gap S and is applied to the concave surface portion 20 of the second concave die N1 by the hydraulic pressure generated between the convex portion 25 of the second convex die N2. And a final molding step in which the remainder is molded all at once until the stage of the final molded product X having a product shape.

  According to the second aspect of the present invention, for example, as shown in the embodiment shown below, the first concave mold M1 on the fixed side and the convex surface portion 15 have a convex shape corresponding to the concave surface portion 10 of the first concave mold M1. A first aperture die M2 configured with a first convex mold M2 that is movable up and down with respect to the concave mold M1, a second concave mold N1 on the fixed side of the product-shaped concave portion 20, and a movable with respect to the concave mold N1. A second convex mold N2 having the same shape as the convex section 15 of the first convex mold M2, in which a gap S is formed between the convex section 25 and the concave section 20 of the second concave mold N1 when lowered to the bottom dead center. The first drawing mold M descends the first convex mold M2 to the bottom dead center with respect to the first concave mold M1. Then, the plate-like blank B is pressurized, and until the stage of the intermediate molded product x in the middle of the product shape in which the liquid reservoir a is formed on the concave side The second drawing die N is set on the concave surface portion 20 of the second concave die N1 with the intermediate molded product x and the liquid reservoir a facing upward with the gap S down, After injecting the liquid W into the liquid reservoir a, the peripheral edge of the intermediate molded product x is pressed by the blank holder 26 and clamped, and at the same time, the second convex mold N2 is placed at the bottom dead center with respect to the second concave mold N1. The intermediate molded product x is pressed along the concave surface portion 20 of the second concave mold N1 by the hydraulic pressure generated between the intermediate molded product x and the convex surface portion 25 of the second convex mold N2. The remaining shape is formed at a stroke until the final shape X of the product shape.

  According to the first aspect of the present invention, the first drawing mold of the hydraulic molding apparatus is used, the first convex mold is lowered with respect to the first concave mold, the blank is pressurized, and the liquid reservoir is formed on the concave side. The intermediate molded product preformed to the intermediate stage of the product shape after being drawn in advance to the intermediate molded product in the middle of the product shape to be die-dead on the concave portion of the second concave mold of the second drawn die Set the liquid reservoir upward with the gap formed between the convex surface of the second convex mold at the point position, inject the liquid into the liquid reservoir, and then press the peripheral edge of the intermediate molded product At the same time as tightening, the second convex mold is lowered to the bottom dead center at once, and the intermediate molded product is pushed into the gap, and the intermediate molded product is moved along the concave surface portion of the second concave mold by the hydraulic pressure generated between the convex portion. Pressure, and the rest is molded all the way to the final shape of the product shape. In this way, it is not necessary to press and hold the blank for clamping until the blank is plastically deformed to the product shape by applying a high hydraulic pressure as shown in FIG. The speed can be increased and the productivity can be significantly improved.

  Moreover, according to the first aspect of the present invention, the first and second drawing molds of the hydraulic forming apparatus to be used adjust the pressure of the liquid filled in the liquid tank as in the prior art. There is no need to provide a separate hydraulic pressure adjustment means, there is no need to use a special hydraulic press machine with a special punch with a convex part in the product shape on the upper die, and the lower die also has a high hydraulic pressure. There is no need to use a special die with a dedicated liquid tank that can be used for both upper and lower dies, which can be configured using general-purpose concave and convex mechanical presses, thus reducing capital investment. Production costs can be significantly reduced.

  According to the second aspect of the present invention, the first concave mold and the second convex mold on the movable side, which constitute the upper mold of both the first drawing mold and the second drawing mold of the hydraulic forming apparatus, are concave portions. Is formed by the same convex general-purpose mechanical press in which the convex surface portion forms a space between the concave portion of the second concave mold and the second concave mold on the fixed side of the predetermined product shape. Therefore, the capital investment can be kept low, and the production cost can be significantly reduced.

It is a schematic sectional drawing which shows the state which shape | molds an intermediate molded product into a final molded product with the 2nd draw die of the hydraulic forming apparatus which concerns on this invention. It is a schematic sectional drawing which shows the structure of a 1st drawing metal mold | die in the state which the 1st convex mold of the same hydroforming apparatus descend | fall to the bottom dead center. It is a schematic sectional drawing which shows the structure of a 2nd aperture die in the state in which the 2nd convex type | mold of the same hydraulic pressure forming apparatus descend | falls to the bottom dead center. It is a schematic sectional drawing which shows the 1st drawing metal mold | die of a blank set stage in a preforming process. It is a schematic sectional drawing which shows the 1st drawing die of the 1st convex mold descending step in a preforming process. It is a schematic sectional drawing which shows the 1st draw die of the press molding stage of the 1st convex mold of an intermediate molded product in a preforming process. It is a schematic sectional drawing which shows the 2nd drawing die of an intermediate molded product carrying-in stage in a last shaping | molding process. It is a schematic sectional drawing which shows the 2nd drawing metal mold | die of an intermediate molded product setting stage in the last shaping | molding process. It is a schematic sectional drawing which shows the 2nd drawing metal mold | die of the liquid injection | pouring stage in the last shaping | molding process. It is a schematic sectional drawing which shows the 2nd draw die in the downward stage of a 2nd convex type | mold in the last shaping | molding process. It is a schematic sectional drawing which shows the 2nd drawing die of the final stage which shape | molded the intermediate molded product into the final molded product. It is a longitudinal cross-sectional view which shows the conventional counter hydraulic forming apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows a state in which an intermediate molded product is formed into a final molded product with a second drawing die of a hydraulic molding apparatus according to the present invention, FIG. 2 shows a structure of the first drawing die of the hydraulic molding device, FIG. 3 shows the structure of the second drawing die. In the present invention, the hydraulic forming apparatus of the illustrated example is an apparatus for obtaining a panel part of an automobile by forming a blank of a thin steel plate, and is characterized in that the blank is an intermediate formed product stage in the middle of the product shape of the panel part. Of the first drawing mold M used in the preforming process for molding up to the final molding process for molding the remainder of the intermediate molded product in the middle of the product shape up to the final molded product stage of the product shape. It is a point consisting of two sets.

  As shown in FIG. 2, the first drawing die M includes a lower first concave mold (die) M1 and an upper first convex mold (punch) M2 that moves up and down relative to the first concave mold M1.

  The first concave mold M1 has a concave surface portion 10 formed by placing a plate-like blank on the upper surface, and is fixed on the base 11 with the concave surface portion 10 facing upward. The first convex mold M2 is provided with a convex surface portion 15 formed by pressing a blank on the lower surface, and the mold main body 14 is fixed to an elevating member 12 that is vertically moved up and down by an elevating drive device, and the convex surface portion 15 is directed downward. It is hung on. In the mold body 14, a guide hole 14 a is recessed in the up and down direction in the figure in the periphery of the convex surface portion 15, and the blank holder 16 is biased in the guide hole 14 a by a plurality of gas springs 17 in the downward projecting direction. It is slidably arranged.

  Therefore, in the first drawing mold M, the concave surface portion 10 of the first concave mold M1 and the convex surface portion 15 of the first convex mold M2 are intermediate molded products x in the middle of the product shape in which the liquid reservoir portion a is formed on the concave side. According to the shape of FIG. 7 (see FIG. 7), a concave shape (outer shape) and a convex shape (inner shape) corresponding to each other are formed.

  As shown in FIG. 3, the second drawing mold N includes a lower second concave mold (die) N1 and an upper second convex mold (punch) N2 that moves up and down relative to the second concave mold N1.

  The second concave mold N1 has a concave surface portion 20 formed by placing a blank on the upper surface thereof, and is fixed on the base 21 with the concave surface portion 20 facing upward. The second convex mold N2 has a convex surface portion 25 that is formed by pressing a blank on the lower surface, and a mold body 24 is fixed to an elevating member 22 that is vertically moved up and down by an elevating drive device, and the convex surface portion 25 is directed downward. It is hung on. In the mold body 24, a guide hole 24a is recessed in the up and down direction in FIG. 3 in the periphery of the convex portion 25, and the blank holder 26 is urged in the guide hole 24a by a plurality of gas springs 27 in the downward projecting direction. Is slidably arranged.

  Therefore, in the second drawing die N, the concave surface portion 20 of the second concave die N1 is formed in the center in accordance with the final molded product (panel part) X having a deep drawing portion d (see FIG. 11). It is formed in a concave shape having a hole 20a. On the other hand, as shown in FIGS. 2 and 3, the second convex mold N2 has a convex surface portion 25 having the same convex shape as the convex surface section 15 of the first convex mold M2 in the first aperture die M, and the second concave mold N1. On the other hand, it is formed in a convex shape in which a gap S is formed between the concave surface portion 20 of the second concave mold N1 that faces the lower dead center when it is lowered.

Now, using the hydraulic forming apparatus according to the present invention having the above-described configuration, for example, a blank of a thin steel plate is formed into a product shape having a deep drawing portion d at the center to obtain a panel component (see FIG. 11). The molding method will be described below.
(1) First stage: Preliminary forming process As shown in FIG. 4, after setting the blank B on the first concave mold M1, as shown in FIG. The lifting / lowering drive unit is actuated to lower the first convex mold M2 with respect to the first concave mold M1, press the peripheral edge of the blank B with the blank holder 16, and clamp the mold as shown in FIG. Intermediate molded product in the middle of the product shape in which the first convex mold M2 is lowered to the bottom dead center against the urging force of the gas spring 17 against M1 and pressurizes the plank B to form the liquid reservoir a on the concave side. Drawing to the stage of x.

(2) Second stage: final molding step Thereafter, as shown in FIG. 7, the intermediate molded product x is conveyed to the second drawing die N, and as shown in FIG. 8, the concave surface portion 20 of the second concave die N1. The intermediate molded product x is set with the liquid reservoir a facing upward with the gap S facing downward, and then, as indicated by an arrow in FIG. Is injected into the liquid reservoir a.

  Next, the lifting drive device is actuated to start the lowering of the second convex mold N2 as shown in FIG. 10, and when the mold is clamped by pressing the peripheral part of the intermediate molded product x with the blank holder 26 as shown in FIG. At the same time, the second convex mold N2 is lowered to the bottom dead center against the urging force of the gas spring 27 against the second concave mold N1, and the intermediate molded product x is pushed into the gap S. At this time, the second convex mold N2 has the liquid W between the convex surface portion 25 and the intermediate molded product x because the convex surface portion 25 pushes the intermediate molded product x into the sealed space S with the liquid W interposed therebetween. As shown in FIG. 11, the intermediate molded product x is pressurized along the concave surface portion 20 of the second concave mold N1 by this hydraulic pressure, and the remainder is squeezed all the way to the final molded product X stage of the product shape. Molded and processed into panel parts.

  As described above, according to the present invention, the first drawing mold M of the hydraulic molding apparatus is used, the first convex mold M2 is lowered with respect to the first concave mold M1, the plank B is pressurized, and the liquid is stored on the concave side. After drawing in advance to the stage of the intermediate molded product x in the middle of the product shape in which the part a is formed (preliminary molding process), the intermediate molded product x preformed to the middle of the product shape is transferred to the second drawn mold N. On the concave surface portion 20 of the second concave mold N1, the liquid reservoir a is set upward with the gap S formed between the convex surface portion 25 of the second convex mold N2 at the bottom dead center, and the liquid reservoir a After injecting the liquid W, the peripheral edge of the intermediate molded product x is pressed by the blank holder 26 and clamped, and at the same time, the second convex mold N2 is lowered to the bottom dead center and the intermediate molded product x is pushed into the gap S. At that time, pressure is applied along the concave surface portion 20 of the second concave mold N1 by the hydraulic pressure generated between the convex surface portion 25 and Since the rest of the product shape is drawn to the stage of the final molded product X (final molding process), until the blank is plastically deformed into the product shape by applying high hydraulic pressure as in the conventional counter hydraulic molding method There is no need to press and hold the blank for a short time, and therefore the machining speed is increased by the amount that the time for holding the clamped state is not required, and the productivity is remarkably improved.

B Blank M 1st drawing mold M1 1st concave mold M2 1st convex mold N 2nd drawing mold N1 2nd concave mold N2 2nd convex mold S Cavity X Final molded product x Intermediate molded product a Liquid reservoir 10/20 Concave surface Part 15/25 Convex part 16/26 Blank holder

Claims (2)

A first drawing mold comprising a first concave mold on the fixed side, and a convex section having a convex shape corresponding to the concave section of the first concave mold, and a first convex mold that is movable up and down with respect to the concave mold; Is formed between the second concave mold on the fixed side of the product shape and the concave section of the second concave mold when the convex surface portion is lowered to the bottom dead center and can be moved up and down with respect to the concave mold. Using a second aperture mold configured with a convex second convex mold having the same shape as the convex convex portion,
In the first drawing mold, the first convex mold is lowered to the bottom dead center with respect to the first concave mold to press the plate-shaped blank, and the liquid reservoir is formed on the concave side. A preforming process to process to the stage of intermediate molded products;
In the second drawing mold, the intermediate molded product is set on the concave surface portion of the second concave mold, the liquid reservoir portion is set upward with the gap below, and liquid is injected into the liquid reservoir portion. From the above, the peripheral edge of the intermediate molded product is pressed and clamped, and at the same time, the second convex mold is lowered with respect to the second concave mold to the bottom dead center, and the intermediate molded product is pushed into the gap and the second convex A final molding step of pressurizing along the concave surface portion of the second concave mold by a hydraulic pressure generated between the convex surface portion of the mold and molding the remainder at a stroke until the final molded product stage of the product shape;
A hydraulic forming method comprising:   A first drawing mold comprising a first concave mold on the fixed side, and a convex section having a convex shape corresponding to the concave section of the first concave mold, and a first convex mold that is movable up and down with respect to the concave mold; Is formed between the second concave mold on the fixed side of the product shape and the concave section of the second concave mold when the convex surface portion is lowered to the bottom dead center and can be moved up and down with respect to the concave mold. A hydraulic forming apparatus comprising a second drawing mold configured by a second convex mold having the same shape as the convex surface portion of the convex mold, wherein the first drawing mold is the first drawing mold with respect to the first concave mold. The first die is lowered to the bottom dead center, presses the plate-shaped blank, and is pre-processed to the intermediate molded product stage in the middle of the product shape in which the liquid reservoir is formed on the concave side. The intermediate molded product is set on the concave surface portion of the second concave mold, the liquid reservoir portion is set upward with the gap below, and liquid is injected into the liquid reservoir portion. After that, the peripheral edge of the intermediate molded product is pressed with a blank holder and clamped, and at the same time, the second convex mold is lowered to the bottom dead center with respect to the second concave mold, and the intermediate molded product is pushed into the gap. Pressurizing along the concave surface portion of the second concave mold by a hydraulic pressure generated between the convex surface portion of the second convex mold, and forming the rest at once until the final molded product stage of the product shape Hydraulic forming device.

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