JP4631541B2 - Hydroforming apparatus for metal plate, hydroforming method therefor, and molded product using them - Google Patents

Description

  The present invention relates to a hydroforming apparatus for a metal plate and a hydroforming method thereof, and more specifically, in forming a metal plate with hydroform, the pressure of a forming medium can be increased, and a high-strength metal plate is used. In particular, the present invention relates to a metal sheet hydroforming apparatus that does not generate cracks or wrinkles even when molding a molded article having a complicated shape, a hydroforming method thereof, and a molded article using them.

  As a processing method for forming a metal plate using a processing liquid as a forming medium and utilizing the liquid pressure, a counter hydraulic forming method and a hydroforming method are widely used.

  Opposite hydraulic forming method supports punch by penetrating the metal plate into the hydraulic chamber filled with machining fluid while holding the metal plate with blank holder and die, and adapting the metal plate to the punch by hydraulic pressure This is a method of forming the shape.

  In this counter hydraulic forming method, the forming medium has a hydraulic pressure of at most several MPa, and even if water leaks from between the metal plate and the die, there is no problem in forming. Is not required. However, because the punch shape is transferred and molded, contact scratches are likely to occur on the molded product in contact with the punch, and the molded product is cracked or wrinkled because of punch molding with a certain blank hold force by the blank holder. It becomes easy.

  On the other hand, in the hydroform method, the metal plate is held between the upper die and the lower die, and the molded product is formed by bulging the metal plate along the cavity shape of the upper die with the processing liquid introduced from the lower die. Since it is a molding method, and the liquid pressure of the molding medium may require a pressure exceeding 100 MPa, various sealing methods and methods for preventing molding defects have been proposed.

  In Patent Document 1, when a metal plate is held between an upper die and a lower die by a hydroform method, a machining fluid is sealed by providing a draw bead over the entire periphery of a cavity provided in the upper die. Proposed method.

  FIG. 1 is an enlarged view of a peripheral portion of a blank showing a cross-sectional configuration of a draw bead provided at a peripheral portion of a cavity used in the hydroforming method of Patent Document 1. A bead groove 5a surrounding the periphery of the cavity 4 is provided on the surface of the die (upper die), and a bead crest 5b provided on the surface of the blank holder (lower die) 2 is provided opposite thereto. A draw bead 5 is configured.

  In the hydraulic bulge forming method of Patent Document 1, the draw bead 5 shown in FIG. 1 is provided to adjust the flow of the flange of the metal plate 3 and to seal the working fluid 6. However, when molding a molded product having a complicated shape, the thickness of the draw bead 5 that is being sealed changes in the molding process and becomes non-uniform as the flow rate of the flange becomes non-uniform. A gap is generated between the mold and the metal plate, and the machining liquid 6 cannot be sealed.

  For this reason, in the draw bead proposed by Patent Document 1, the shape of the metal plate that can be molded is greatly limited. For example, a molded product having a small radius of curvature (R) uses a high-pressure working fluid, so that the seal is further improved. It may be difficult to form a metal plate. Therefore, in order to achieve both the adjustment of the flow of the flange and the securing of the seal of the working fluid by the draw bead, it is necessary to adjust the bead shape and the arrangement position according to the portion of the metal plate.

  In Patent Document 2, a plate-shaped material is held between a lower mold and an upper mold on which a bead body that can protrude is formed, and the drive amount of the bead body is controlled, and the inflow amount, inflow speed, The inflow resistance is adjusted to suppress the generation of wrinkles due to excessive inflow and the occurrence of cracks due to thinning of the plate thickness. However, in the hydraulic pressure forming method of Patent Document 2, the sealing mechanism is not taken into consideration, and the metal plate is formed only by driving control of a partially provided bead body. A working fluid cannot be obtained, and the shape that can be molded is extremely limited.

  In Non-Patent Document 1, a hydraulic bulge is used as a preliminary molding, and a study is made on a dual hydraulic bulge molding method in which a mold is pressed into a bulged state to obtain a final shape with a working fluid and a mold. Is a so-called lock bead that restrains the flange flow of the metal plate. However, when hydraulic bulge forming is performed using a lock bead, the metal plate flange is completely fixed and cannot flow into the bulging process part, so the metal plate is formed only by overhanging. There will be significant restrictions on the shapes that can be produced.

  In the hydroforming method of Non-Patent Document 2, an O-ring is used as a seal ring of a seal mechanism, and a metal plate is formed by sealing a machining fluid. However, the O-ring of Non-Patent Document 2 can function as a sealing mechanism because the shape of the molded product is an object of the axis, the flange of the metal plate flows in uniformly around the circumference, and the pressure of the pressure medium Is because it is as low as 260 bar (26 MPa). Therefore, when molding a molded product having a complicated shape, the hydraulic pressure of the molding medium becomes high, and the inflow behavior toward the cavity becomes uneven depending on the part of the metal plate. The O-ring is damaged such as entanglement and biting out, and the sealing function cannot be exhibited.

JP 2002-254118 A Japanese Patent Laid-Open No. 2003-266132 RIKEN Report, Vol. 49, No. 1, pp. 1-11 ADVANCED TECHNOLOGY OF PLASTICITY (2002), Vol 2, pages 1009-1014

  As described above, when the metal sheet (sheet) is hydroformed, the molding medium used has a high pressure and the molded product has a complicated shape. It is difficult to ensure both. For this reason, when this inventor applied hydroform to shaping | molding of a metal plate (sheet | seat), it examined the malfunction which generate | occur | produces when using an O-ring as a seal ring for a seal mechanism.

  FIGS. 2A and 2B are diagrams for explaining a damaged state that occurs in an O-ring when hydroforming a metal plate. FIG. 2A shows a engulfed state, and FIG. 2B shows a biting state. When hydroforming a molded product having a complicated shape from the metal plate 3, the metal plate 3 flows toward the cavity while causing relative sliding with the O-ring 7 (in the direction of the arrow 3A). Is uneven depending on the molding part, and the O-ring 7 having a circular cross section is liable to be twisted, and the O-ring 7 is entangled in a part where the flange inflow is large (FIG. 2A). The O-ring 7 will be damaged by dropping off to the side.

  On the other hand, when a non-uniform distribution occurs in the plate thickness of the flange portion as the metal plate 3 flows into the flange, the gap between the lower mold 2 and the metal plate 3 in the seal ring groove 8 becomes non-uniform. For this reason, there is no gap between the lower mold 2 and the metal plate 3 before molding, and even if the metal plate 3 is pressed with a sufficient load by the lower mold 2, a gap is partially generated during the molding process. To do. In particular, when the forming medium is at a high pressure, the O-ring 7 bites out (FIG. 2 (b)), bites out from the seal ring groove 8 to the outer peripheral side, breaks, and seal leakage occurs. In addition, arrow 6A in a figure shows the effect | action direction of a process liquid.

  As a countermeasure against the above-mentioned O-ring biting, the method of inserting a backup ring along the O-ring can also be applied. However, as the inflow amount of the flange becomes uneven, the lower mold and the metal are partly formed during the molding process. Since the gap with the plate fluctuates, the O-ring biting cannot be avoided and cannot be an effective measure.

  Furthermore, when hydroforming metal plates (sheets), it is necessary to constrain the lower die with a clamping force that is greater than the "pressure receiving area x hydraulic pressure" received by the metal plate from the machining fluid in order to prevent the mold from floating. is there. However, since the flange width is designed to be the minimum from the viewpoint of the material yield of the metal plate, when molding a large molded product with hydroform, an excessive clamping force is applied to the flange with a limited metal plate. As a result, the surface pressure received by the narrow area portion of the mold increases, and there is a risk of deformation or breakage of the mold.

  The present invention has been made in view of the above-described problems, and in a hydrofoam in which a metal plate (sheet) is formed along a cavity of an upper mold with a working liquid, a good sealing property is secured, and the metal plate By adjusting the flange inflow amount, a metal plate hydroforming device that does not cause cracks or wrinkles even when a molded product having a complicated shape is formed using a high-strength metal plate, and its It aims at providing a hydroforming method and a molded article using them.

  Conventionally used seal rings and O-rings are premised on a structure that is fixed to the seal portion, or on the premise of an axially symmetric load load, so that hydroform cannot be applied to the formation of a metal plate. In other words, when hydroforming is applied, the conventional O-ring receives shearing force due to non-uniform inflow behavior of the metal plate flange, and the gap between the metal plate and the seal part is not uniform during the molding process. Therefore, entrainment and biting will occur.

  Therefore, the present inventor has made various studies in order to solve the above problems, and as a result, in the hydroforming method of a metal plate (sheet), in order to ensure good sealing performance and adjust the inflow amount of the flange. Noted that it is necessary to arrange a seal mechanism that employs an appropriate seal ring and a draw bead that adjusts the inflow amount of the flange separately from the seal mechanism. Furthermore, it has been found that the optimization of the cross-sectional shape is effective in preventing the entrainment and biting that have been a problem with conventional O-rings.

The present invention has been completed based on the above-mentioned attention and technical knowledge. The following (1) and (2) metal plate hydroforming apparatuses, the following (3) and (4) hydroforming methods, and The summary is the molded product used.
(1) A cavity having the same inner shape as the outer shape of the molded product and an upper die having a plate pressing surface provided at the peripheral portion thereof, and a plate pressing surface at a portion corresponding to the plate pressing surface of the upper die A lower die that holds the metal plate together with the upper die facing the cavity, means for introducing a forming medium between the metal plate and the lower die, and a plate pressing surface of the lower die A seal ring groove with a seal ring installed over the entire circumference, and a part of the outer peripheral side or the inner peripheral side of the seal ring groove, which is partially disposed on the peripheral edge of the cavity with a small drawing resistance. A draw bead composed of a bead groove provided on the plate pressing surface of the mold and a bead crest provided on the plate pressing surface of the upper mold or the lower mold so as to be fitted in the bead groove;
The section parallel to the direction in which the molding medium of the seal ring mounted in the seal ring groove acts is substantially rectangular, and a partial convex portion is provided on the upper section contacting the metal plate, and A partial recess is provided in the lower cross section that abuts the bottom of the seal ring groove,
Driving the introduction means introduces a forming medium having a hydraulic pressure of 100 MPa or more, and bulges the metal plate along the cavity of the upper mold while adjusting the inflow amount of the metal plate. This is a hydroforming apparatus for a metal plate characterized by the following.
(2) In the metal plate hydroforming apparatus according to (1), the contact surface between the upper die and the lower die is provided in addition to the plate pressing surfaces of the both, and the clearance of the plate pressing surface is that of the metal plate. It is desirable that the surface area of the upper mold and the lower mold be held to be greater than the plate thickness and that the projected area on the inner side of the seal ring be greater than the projected area. Thereby, a deformation | transformation and damage of a metal mold | die can be prevented.
(3) A cavity having the same inner shape as the outer shape of the molded product and an upper die having a plate pressing surface provided at the peripheral portion thereof, and a plate pressing surface at a portion corresponding to the plate pressing surface of the upper die Using the lower mold provided, the metal plate is held facing the cavity, and a seal ring groove with a seal ring is provided so as to cover the entire circumference of the plate pressing surface of the lower mold, The section parallel to the direction in which the molding medium of the seal ring mounted in the seal ring groove acts is substantially rectangular, and a partial convex portion is provided on the upper section contacting the metal plate, and It is configured so that a partial recess is provided in the lower cross section that contacts the bottom of the seal groove
Further, a draw bead in which a bead groove provided on the upper or lower plate holding surface and a bead crest provided on the lower or upper plate holding surface is fitted is provided on the outer peripheral side of the seal ring groove. Alternatively, it is partly provided at the peripheral edge of the cavity which is a part on the inner peripheral side and has a small drawing resistance, and a forming medium having a hydraulic pressure of 100 MPa or more is introduced between the metal plate and the lower mold, The metal plate hydroforming method is characterized in that the metal plate is swelled along the upper mold cavity while adjusting an inflow amount.
(4) In the metal plate hydroforming method of (3) above, a contact surface between the upper die and the lower die is provided in addition to the plate pressing surface of both, and the clearance of the plate pressing surface is set to the plate of the metal plate. It is desirable to keep the thickness more than. Thereby, a deformation | transformation and damage of a metal mold | die can be prevented.

Further, by providing a step on the outer peripheral side of the upper cross section of the seal ring that contacts the metal plate and disposing a reinforcing material having a higher strength than the seal ring, even when using a high-pressure working fluid, the seal The ring biting can be prevented more effectively.
(6) A molded product produced by using the metal sheet hydroforming apparatus (1) or (2) or the metal sheet hydroforming method (3) or (4).

  According to the hydroforming apparatus and the hydroforming method of the metal plate of the present invention, the seal ring groove having the seal ring is provided over the entire circumference of the lower plate holding surface of the mold, and the outer peripheral side of the seal ring groove. Alternatively, by placing a draw bead composed of a bead groove and a bead crest on the inner peripheral side, it becomes possible to increase the pressure of the forming medium, further ensuring a good sealing property and at the same time reducing the inflow amount of the flange. Since it can be adjusted, cracks and wrinkles are not generated even when a molded product having a complicated shape is formed using a high-strength metal plate.

  In addition, when molding large molded products with hydrofoam, by eliminating the restraint of the metal plate with excessive clamping force, preventing deformation and breakage of the mold and improving the durability of the mold, The manufacturing cost of the molded product manufactured using the hydroforming apparatus and hydroforming method of the metal plate of this invention can be aimed at.

(Hydrofoam device and hydrofoam method)
Embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing the overall configuration of the hydroform apparatus of the present invention, in which (a) shows the configuration before molding in which the upper and lower molds hold the metal plate, and (b) shows the metal plate. The structure after the shaping | molding which carried out the swelling process is shown, (c) has shown the perspective view of the molded article manufactured using the hydroforming apparatus of this invention.

  The metal plate 3 as a molding material is placed on the upper surface of the lower mold 2 fixed to the bed 12, and the upper mold 1, the lower mold 2, and the lower mold 2 are lowered by lowering the slide 11 of the press machine to which the upper mold 1 is attached. In this configuration, the metal plate 3 is held. The upper die 1 is provided with a cavity 4 having the same inner shape as the outer shape of the molded product, and a plate pressing surface 1 a is provided at the peripheral portion of the cavity 4. Similarly, a plate pressing surface 2a of the lower mold 2 is provided at a portion corresponding to the plate pressing surface 1a of the upper mold, and the flange of the metal plate 3 is held by the upper and lower plate pressing surfaces 1a, 2a. ing.

  As a forming medium introducing means, a machining liquid injection path 2b and a discharge path 2c are provided that open on the surface of the lower mold 2 facing the cavity. The injection path 2b and the discharge path 2c are each connected to an external pipe through a joint. On the other hand, the upper mold 1 is provided with an air vent hole 1c for discharging the air in the cavity 4 to the outside during the molding process.

  As a sealing mechanism, a seal ring groove 8 fitted with a seal ring is provided over the entire circumference of the lower plate pressing surface 2a, and the machining liquid 6 is sealed in the machining process. Further, separately from the sealing mechanism, a draw bead 5 for adjusting the inflow amount of the flange is disposed.

  The draw bead 5 compensates for a lack of drawing resistance, and a bead groove provided in the upper plate holding surface 1a for suppressing the inflow amount and imparting drawing resistance by bending deformation when the flange of the metal plate passes. 5a and the bead pile 5b provided on the lower plate holding surface 2a are configured to be fitted. In the present invention, a bead groove may be provided on the lower plate holding surface, and a bead crest may be provided on the upper plate holding surface for fitting.

  Therefore, the seal ring groove 8 is provided over the entire circumference of the cavity peripheral portion, whereas the draw bead 5 is formed by, for example, the right side portion of the cavity peripheral portion of the molded product 13 as shown in FIG. The flange is selectively disposed at a site where it is necessary to increase the drawing resistance of the flange.

  Next, in order to reduce the pressure receiving area of the metal plate and reduce the required clamping force, the seal ring groove and the draw bead should be arranged as close as possible to the periphery of the cavity. desirable. For this reason, the draw bead 5 is preferably arranged on the outer peripheral side of the seal ring groove 8 as shown in FIGS.

  However, when the inflow amount of the flange increases, if the flange whose shape or thickness has changed extremely after passing through the draw bead passes through the seal ring groove, the seal ring is damaged and the sealing function is significantly reduced. It will be. In such a case, it is desirable to arrange a draw bead between the seal ring groove and the peripheral edge of the cavity. The arrangement position of the draw bead is not limited to the portion on the outer peripheral side of the seal ring groove, but is appropriately selected according to the hydrofoam processing conditions.

  As shown in FIG. 3 (a), when the metal plate is hydroformed, the metal plate 3 is held by the upper mold 1 and the lower mold 2 and then the machining liquid 6 is transferred from the external pipe through the machining liquid injection path 2b. It inject | pours between the metal plate 3 and the lower mold | type 2 of the site | part facing the tee 4. FIG. When air remains between the metal plate 3 and the lower mold 2, the air is discharged together with the machining liquid 6 from the machining liquid discharge path 2 c.

  Thereafter, when the pressure of the working fluid 6 is increased, the metal plate 3 in the cavity swells, and after the top of the swelled part comes into contact with the upper die 1 surface, the contact area expands with the molding, and the cavity 4 And expand to the periphery. The air remaining between the metal plate 3 and the upper mold 1 is discharged from the air vent hole 1c.

  As shown in FIG. 3B, the bulging portion of the metal plate 3 comes into contact with the entire inner portion of the cavity 4 as the bulging process progresses, whereby the molding of the molded product 13 is completed. Then, the molded product 13 can be taken out by lowering the pressure of the working fluid 6 to discharge the working fluid 6 and raising the upper mold 1.

In the molded product 13 shown in FIG. 3C, in order to adjust the inflow amount of the flange, the draw bead is arranged at the right side portion of the cavity peripheral portion where the drawing resistance of the flange is small.
(Cross sectional shape of seal ring)
The cross section of the seal ring employed in the present invention is substantially rectangular, and a partial convex portion is provided on the upper cross section that contacts the metal plate, and a partial concave portion is provided on the lower cross section that contacts the bottom of the seal groove. It is desirable to provide. With such a cross-sectional shape, the seal ring does not easily rotate in the seal ring groove, and does not become entangled due to uneven sliding of the local metal plate, and partially the lower mold and the metal plate. No biting occurs even if there is a gap.

  FIG. 4 is a view showing a cross section of a seal ring that can be employed in the present invention, and (a) to (g) show specific cross-sectional shape examples. An arrow 6A in FIG. 4 indicates a direction in which the machining fluid 6 acts on the seal ring groove 8, and a cross section of the seal ring 9 parallel to this is preferably formed in a substantially rectangular shape. As a result, a flat portion can be secured on the bottom and side surfaces of the seal ring groove 8, and the filling rate of the seal ring 9 in the seal ring groove 8 can be increased. It can suppress that it rotates within.

  Furthermore, a partial convex part can be provided in the upper cross section with which the seal ring 9 contacts the metal plate. By providing a partial projection that abuts the metal plate, the contact area with the metal plate can be reduced and the surface of the metal plate can be abutted while maintaining high surface pressure, thus maintaining excellent sealing performance. be able to.

  At the same time, a partial recess can be provided in the lower cross section that contacts the bottom of the seal ring groove 7. By providing a recess on the surface that contacts the bottom of the seal ring groove, the rigidity at the time of crushing of the seal ring 9 is adjusted, the contact area between the seal ring 9 and the groove bottom is reduced, and a high surface pressure is maintained. So that the surface pressure between the bottom of the seal ring groove 8 and the seal ring 9 can be increased, and the sealing performance can be ensured.

  FIG. 4 is an illustration of the cross-sectional shape of the seal ring that can be employed in the present invention, and the present invention is not limited to these, and any cross-sectional shape that exhibits the above-described action can be used in the present invention. The cross section of the seal ring to be defined can be used.

In the present invention, the material of the seal ring is not limited, but from the viewpoint of sliding with a metal plate, compatibility with a working fluid (oil, emulsion, etc.), strength and rigidity, NBR, fiber reinforced NBR, and It is desirable to apply an elastomer or the like.
(Seal ring with excellent biting prevention)
If the seal ring of the present invention has the cross-sectional shape shown in FIG. 4, it is possible to exert an entrainment preventing effect that cannot be compared with a conventionally used O-ring. However, in metal sheet (sheet) hydroforming, it is expected that the gap between the lower mold and the metal sheet will change locally due to fluctuations in the plate thickness due to the inflow of the flange, and that the working fluid will be at a high pressure. Is done.

  In such a situation, the seal ring 9 is pressed by the machining liquid, and there is a possibility that biting occurs between the lower plate holding surface 2 a and the metal plate 3. In such a case, it is desirable to provide a step on the outer peripheral side of the upper cross section that contacts the metal plate 3 of the seal ring 9 shown in FIG. .

  FIG. 5 is a diagram showing a cross section of a seal ring that can be employed in the present invention and is excellent in preventing biting, and (a) to (d) show specific cross-sectional shape examples. The basic cross-sectional shape is the same as that of the seal ring 9 shown in FIG. 4, but a step is provided on the outer peripheral side of the upper cross-section that comes into contact with the metal plate, and a reinforcing material 9a having higher strength than the seal ring 9 is arranged. It is.

  FIG. 6 is a diagram for explaining the biting prevention behavior exhibited by the seal ring shown in FIG. 5, wherein (a) shows a state in which the metal plate is held by the upper mold and the lower mold before molding, (B) has shown the state by which the hydraulic pressure was loaded in the shaping | molding process. In the state shown in FIG. 6A, the convex portion provided on the upper cross section of the seal ring 9 is crushed by the metal plate 3, and abuts against the metal plate 3 in a state where the reinforcing material 9a is disposed on the outer peripheral side.

  In the state shown in FIG. 6 (b), a high-pressure machining fluid (arrow 6A) is applied during the molding process, and the plate thickness fluctuates due to the inflow of the flange. As a result, a minute gap is formed. Here, when the seal ring 9 is pressed against the outer peripheral side by the hydraulic pressure of the working fluid (arrow 6A), the lower seal ring 9 in which the reinforcing material 9a is disposed is compressed and deformed in the lateral direction (direction of arrow A). Stretching deformation in the vertical direction (the direction of arrow B) occurs. By the combination of compression deformation and stretching deformation of the seal ring 9, the reinforcing material 9a is pressed against the metal plate 3, and the gap between the metal plate 3 and the reinforcing material 9a is eliminated, thereby preventing the seal ring 9 from biting out. can do.

  FIG. 5 shows examples of the cross-sectional shape of the seal ring excellent in biting prevention that can be employed in the present invention, and is not limited to these, but has a cross-sectional shape that exhibits the above-described action. If it exists, it can be set as the cross section of the seal ring prescribed | regulated by this invention.

The reinforcing material needs to be stronger than the seal ring, but the material is not limited. However, it is desirable to employ beryllium copper, gun metal, bronze, aluminum bronze, PTFE, soramite, etc. in order to slide on the metal plate and further prevent burn-in. Further, the reinforcing material may be a structure that is fixed to the seal ring, or may be a structure that is removable. As an additional effect of using the reinforcing material, the high-strength reinforcing material can be fitted into the seal ring groove to effectively prevent the seal ring from falling off.
(Prevents deformation and breakage of mold)
FIG. 7 is a view showing a main part for sandwiching the metal plate between the upper mold and the lower mold in the hydroform apparatus of the present invention. Normally, when the metal plate 3 is formed using a hydroforming apparatus, the molds 1 and 2 are clamped so that the metal plate 3 receives from the working fluid “pressure receiving area × hydraulic pressure” or more so as not to float. It is necessary to restrain the lower mold 2 with force.

  When molding large molded products with hydroform, if the flange width is designed to be the smallest from the viewpoint of the yield of the metal plate, excessive clamping force will be applied to the flange part where the metal plate is limited before molding. Will be loaded. On the other hand, in the molding process, the shrinkage flange portion increases in thickness and the extension flange portion decreases in thickness, so that the load per piece increases. Therefore, the surface pressure received by the mold is locally increased, and there is a possibility that the mold is deformed or broken.

  As measures against these, as shown in FIG. 7, when performing mold clamping, the upper mold 1 and the lower mold 2 are brought into contact with each other via the stopper 10, and the mold clamping force is provided on the plate pressing surfaces 1 a and 2 a. The structure is such that it is received by the stopper 10 provided. Further, the clearance between the upper mold 1 and the lower mold 2 of the flange portion of the metal plate is set to be equal to or greater than the plate thickness of the metal plate 3 so that the clamping force is not applied to the metal plate 3. The area can be selected freely.

  Further, by making the contact area between the upper mold and the lower mold equal to or larger than the projected area inside the seal ring groove 8, the surface pressure due to the mold clamping force applied to the stopper 10 can be reduced to less than the hydraulic pressure. Therefore, it is desirable for improving the durability of the mold.

Example 1
In Example 1, the test was performed using the hydroform apparatus of the present invention shown in FIG. 3 and the hydroform apparatus shown in FIG. The hydroform apparatus shown in FIG. 8 is different from the hydroform apparatus shown in FIG. 3 in that the seal ring groove is not provided and that the draw bead 5 is provided over the entire circumference of the cavity peripheral part. Other configurations are the same.

  Further, in the hydroform apparatus of the present invention shown in FIG. 3, an O-ring is used as a comparative example of the seal ring, and the cross-sectional shape shown in FIG. The thing of the cross-sectional shape shown to a) was used.

  The shape of the upper mold cavity, which is the product shape, was set to a plane dimension of 400 mm square, a bottom curvature of 2000 mm, and a maximum depth of 60 mm. A forming test was performed using a thin steel plate having a thickness of 0.7 mm and a tensile strength of 600 MPa as a test material.

  In the molding test using the hydroform apparatus shown in FIG. 8, seal leakage occurred from a hydraulic pressure of 100 MPa, and bulge processing along the cavity shape could not be performed. For this reason, when trying to prevent seal leakage by increasing the plate pressing force, the inflow of the flange did not occur, and the test material was cracked during the molding process and could not be molded.

In the molding test using the hydroform apparatus of the present invention shown in FIG. 3, the O-ring was first tested. As a result, the O-ring dropped from the seal ring groove and could not be sealed. Next, when the test was performed using the seal ring having the cross-sectional shape shown in FIG. 4A, bulging processing along the cavity shape was possible. Furthermore, when tested using a seal ring having a cross-sectional shape shown in FIG. 5A, swelling along the cavity shape is possible, and the seal may be damaged even if the hydraulic pressure exceeds 200 MPa. The seal did not leak.
(Example 2)
In Example 2, the test was performed using the hydroform apparatus of the present invention shown in FIG. 7 and the hydroform apparatus of the comparative example shown in FIG. In the hydroforming apparatus of the present invention, the mold clamping load is received by the stopper 10 provided on the outer peripheral side without being received by the flange portion of the metal plate 3 using the seal ring having the cross-sectional shape shown in FIG. It was.

  The shape of the cavity of the upper mold, which is the product shape, was set to a plane dimension of 400 mm square, a bottom curvature of 2000 mm, and a maximum depth of 60 mm. A forming test was performed using a thin steel plate having a thickness of 0.7 mm and a tensile strength of 300 MPa as a test material.

Although any hydroforming apparatus could be swelled along the cavity shape, after 10,000 tests, in the mold of the comparative hydroforming apparatus shown in FIG. In the portion where the inflow of the flange is large, significant wear was observed. On the other hand, in the hydroform apparatus of the present invention shown in FIG. 7, the wear of the mold could not be confirmed.
(Example 3)
FIG. 9 is a diagram showing a configuration of a hydroform apparatus and a shape of a molded product that were subjected to a molding test as a comparative example in Example 3. FIG. 9A shows a cross-sectional configuration of the apparatus, and FIG. Shows the appearance of the planar configuration of the molded product. The hydroform apparatus of the comparative example shown in FIG. 9 is the example of the present invention shown in FIG. 10 below that the seal ring groove is not provided and that the draw beads 5 are provided over the entire circumference of the cavity peripheral part. This is different from the hydroform equipment.

  FIG. 10 is a diagram showing a configuration of a hydroform apparatus and a shape of a molded product that were subjected to a molding test as an example of the present invention in Example 3, and (a) shows a cross-sectional configuration of the apparatus, and (b) ) Shows the appearance of the planar configuration of the molded product. Further, in the hydroform apparatus of the present invention example, the seal ring having the cross-sectional shape shown in FIG.

9 and 10, a forming test was conducted using a thin steel plate having a thickness of 0.7 mm and a tensile strength of 350 MPa as a test material. In the comparative hydroform apparatus shown in FIG. When the force was increased, cracks occurred at the corner (A part) on the corner bottom side, and when the clamping force was weakened, wrinkles occurred at the step boundary part (B part).

  On the other hand, in the hydroforming apparatus of the present invention example shown in FIG. 10, water leakage can be prevented by the seal ring provided over the entire circumference, the mold is not lifted by the hydraulic pressure by the clamping force, and the flange It did not inhibit the inflow. For this reason, since sufficient inflow of the flange can be secured, there is no crack in the molded product, and the inflow amount of the flange can be appropriately adjusted by partially arranging the draw beads, and wrinkle generation can be prevented.

According to the hydroforming apparatus and the hydroforming method of the metal plate of the present invention, the seal ring groove having the seal ring is provided over the entire circumference of the lower plate holding surface of the mold, and the outer peripheral side of the seal ring groove. Alternatively, by partially disposing a draw bead composed of a bead groove and a bead crest on the inner peripheral part at the peripheral edge of the cavity where the drawing resistance is small , it becomes possible to increase the pressure of the molding medium, which is even better. Since the amount of inflow of the metal plate flange can be adjusted at the same time as ensuring sealing performance, cracks and wrinkles can be generated even when molding a complex shaped product using a high-strength metal plate. There is no.

  In addition, when molding large molded products with hydroform, by eliminating the restraint of the metal plate with excessive clamping force, preventing deformation and breakage of the mold and improving the durability of the mold, Since the manufacturing cost of the molded product manufactured using the hydroforming apparatus and hydroforming method of the metal plate of the present invention can be reduced, the metal plate (sheet) can be widely applied as a bulging technique. it can.

It is an enlarged view of the blank peripheral part which shows the cross-sectional structure of the draw bead provided in the cavity peripheral part by the hydroforming method of patent document 1. FIG. It is a figure explaining the breakage state which generate | occur | produces in an O-ring when performing the hydroforming of a metal plate, (a) shows the winding state and (b) shows the biting state. It is a figure which shows the whole structure of the hydroforming apparatus of this invention, (a) shows the structure before shaping | molding which held the metal plate with the upper mold | type and the lower mold | type, (b) bulged the metal plate. The structure after shaping | molding is shown, (c) has shown the perspective view of the molded article manufactured using the hydroforming apparatus of this invention. It is a figure which shows the cross section of the seal ring which can be employ | adopted by this invention, (a)-(g) has shown the specific cross-sectional shape example. It is a figure which shows the cross section of the seal ring excellent in biting prevention which can be employ | adopted by this invention, (a)-(d) has shown the specific cross-sectional shape example. It is a figure explaining the biting prevention behavior which the seal ring of the present invention exhibits, (a) shows a state where the metal plate is held by the upper mold and the lower mold before molding, (b) is the molding This shows a state in which the hydraulic pressure is applied in the process. It is a figure which shows the principal part which clamps a metal plate with the upper mold | type and lower mold | type in the hydroforming apparatus of this invention. It is a figure which shows the structure of the apparatus of the hydrofoam which implemented the shaping | molding test as a comparative example in Example 1, and the shape of the shape | molded molded article, (a) shows the cross-sectional structure of an apparatus, (b) is a molded article. The external appearance of a planar configuration is shown. It is a figure which shows the structure of the apparatus of the hydrofoam which implemented the shaping | molding test as a comparative example in Example 3, and the shape of the shape | molded molded article. It is a figure which shows the structure of the apparatus of the hydrofoam which implemented the shaping | molding test as Example of this invention in Example 3, and the shape of the shape | molded molded article.

Explanation of symbols

1: Upper mold 2: Lower mold 1a, 2a: Plate holding surface 3: Metal plate 4: Cavity 5: Draw bead 6: Molding medium, machining fluid 7: O-ring 8: Seal ring groove 9: Seal ring 10: Stopper 11: Slide 12: Bed 14: Molded product

Claims (6)

An upper die having a cavity having the same inner shape as the outer shape of the molded product and a plate pressing surface provided at the peripheral portion thereof;
A plate holding surface is provided in a portion corresponding to the plate holding surface of the upper die, and a lower die that holds the metal plate together with the upper die facing the cavity,
Means for introducing a forming medium between the metal plate and the lower mold;
A seal ring groove fitted with a seal ring over the entire periphery of the lower plate holding surface;
A bead groove provided on the upper plate or the lower plate holding surface, which is partly disposed on the outer peripheral side or the inner peripheral side of the seal ring groove and partially disposed on the peripheral edge of the cavity having a small drawing resistance, and the bead A draw bead composed of a bead ridge provided on the plate pressing surface of the upper mold or the lower mold so as to be fitted in the groove,
The section parallel to the direction in which the molding medium of the seal ring mounted in the seal ring groove acts is substantially rectangular, and a partial convex portion is provided on the upper section contacting the metal plate, and A partial recess is provided in the lower cross section that abuts the bottom of the seal ring groove,
Driving the introduction means introduces a forming medium having a hydraulic pressure of 100 MPa or more, and bulges the metal plate along the cavity of the upper mold while adjusting the inflow amount of the metal plate. A hydroforming device for metal plates.   The metal plate hydroforming apparatus according to claim 1, wherein a stepped portion is provided on an outer peripheral side of an upper cross section of the seal ring that contacts the metal plate, and a reinforcing material having a higher strength than the seal ring is disposed. .   2. The contact surface between the upper die and the lower die is provided in addition to the plate pressing surfaces of both, and the clearance of the plate pressing surface is maintained to be equal to or greater than the plate thickness of the metal plate. 2. A metal sheet hydroforming apparatus according to 2. A cavity having the same inner shape as the outer shape of the molded product and an upper die having a plate pressing surface provided at the peripheral portion thereof, and a plate pressing surface provided at a portion corresponding to the plate pressing surface of the upper die Using the lower mold, holding the metal plate facing the cavity,
A seal ring groove fitted with a seal ring is provided so as to extend over the entire circumference of the lower plate holding surface, and a section parallel to the direction in which the molding medium of the seal ring fitted in the seal ring groove acts is generally It is rectangular and is configured such that a partial convex portion is provided on the upper cross section contacting the metal plate, and a partial concave portion is provided on the lower cross section contacting the bottom of the seal groove,
Further, a draw bead in which a bead groove provided on the upper or lower plate holding surface and a bead crest provided on the lower or upper plate holding surface is fitted is provided on the outer peripheral side of the seal ring groove. Or it is a part on the inner peripheral side and is partially provided on the peripheral edge of the cavity where the drawing resistance is small,
A molding medium having a hydraulic pressure of 100 MPa or more is introduced between the metal plate and the lower die, and the metal plate is swelled along the cavity of the upper die while adjusting the inflow amount of the metal plate. A hydroforming method for a metal plate, characterized by processing.   The metal plate hydroforming method according to claim 4, wherein a step portion is provided on an outer peripheral side of an upper cross section that contacts the metal plate of the seal ring, and a reinforcing material having higher strength than the seal ring is disposed. .   6. The contact surface between the upper mold and the lower mold is provided in addition to the plate pressing surfaces of the both, and the clearance of the plate pressing surface is maintained to be equal to or greater than the plate thickness of the metal plate. The hydroforming method of the metal plate as described.

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