JP5557374B2 - Press mold - Google Patents

Description

  The present invention relates to a press mold, and more particularly, to a mold used for overhang molding in which a blank is stretched and pressed against a molding surface of a punch to mold a design surface.

  For example, as shown in FIGS. 10 and 11, a press-molding die disclosed in Patent Document 1 includes a punch 103 having a molding surface 103 a and a die 101 that can be moved up and down relative to the punch 103. And a blank holder 102 that can be raised and lowered provided around the punch 103. In this mold, first, the die 101 is relatively lowered, and the end portion of the blank W is sandwiched between the die 101 and the blank holder 102 (see FIG. 10), and the die 101 and the blank holder 102 are lowered in this state. Then, the blank material W is pressed against the molding surface 103a of the punch 103 and stretched, so that the blank material W is plastically deformed and formed into a predetermined shape (see FIG. 11).

JP 10-43820 A

  In a press mold that performs an overhang process, it is necessary to hold the end of the blank material in order to sufficiently stretch the blank material while preventing the generation of wrinkles. As a mechanism for holding the end portion of the blank material in this way, as shown in Patent Document 1, it is common to provide a blank holder that can be moved up and down. In this case, the press mold requires at least three members, ie, a punch, a die, and a blank holder. Further, as a mold drive mechanism, a drive mechanism for raising and lowering a die (or punch) and a drive mechanism for raising and lowering a blank holder are required.

  However, the demand for cost reduction for press molding is severe, and it is required to reduce the manufacturing cost of the mold and drive energy during press molding.

  In addition, when the blank holder is pushed down by the die, the end of the blank material can be held between the die and the blank holder by applying a predetermined cushion pressure (a force against the pushing force) to the blank holder. However, since it is difficult to keep the cushion pressure of the blank holder constant, there is a possibility that the holding force at the end of the blank material differs due to the variation of the cushion pressure and the processing quality of the product becomes unstable.

  The problem to be solved by the present invention is to reduce the manufacturing cost and driving energy of the press mold and stabilize the processing quality.

In order to solve the above-described problems, the present invention includes a punch having a molding surface and a die provided so as to be relatively close to or away from the punch, and stretches the blank material while pressing it against the molding surface. A press-molding die used for overmolding to form, wherein a punch is formed with a recess so as to surround the outer periphery of the molding surface, and a die is formed with a protrusion inserted into the recess, A holding mechanism that folds and holds the end portion of the blank material at the convex portion and the concave portion by inserting the convex portion into the concave portion with the punch relatively approached, and among the blank material, by the holding mechanism by pushing the area inside the bent portion into the recess in the convex portion, provided the stretching mechanism stretching while pressing the blank to the forming surface, the folding of the blank In a state where the region outside the bent portion is sandwiched between the convex portion and the concave portion, the die and the punch are relatively approached to stretch the blank material, and the region outside the bent portion of the blank material is sandwiched. The wall surface of the convex portion and the wall surface of the concave portion facing the convex portion have a waveform shape having the same phase in which peaks and troughs appear alternately along the circumferential direction of the molding surface .

  In this press molding die, the end of the blank material is bent and held by inserting the convex portion into the concave portion, thereby restricting the blank material from being drawn to the molding surface side. After the end portion is bent and held in this manner, the blank material is pressed against the molding surface and stretched by pushing the region inside the bent portion of the blank material into the concave portion by the convex portion. Thus, since the blank material can be held and stretched only by the die (convex portion) and the punch (concave portion), the blank holder becomes unnecessary, the number of parts is reduced, and the driving energy for driving the blank holder Is no longer necessary. In addition, the force that holds the blank material by the bending mechanism depends on the dimensional accuracy of the mold, especially the dimensional accuracy of the protrusions formed on the punch and the recesses formed on the die, so there is little variation and stable processing quality. Can be made.

  In the above press molding die, if the region outside the bent portion of the blank material is sandwiched between the convex portion and the concave portion, the end portion of the blank material can be reliably held. At this time, the in-phase corrugated shape in which peaks and valleys alternately appear along the circumferential direction of the molding surface between the wall surface of the convex portion and the wall surface of the concave portion that sandwich the outer region of the bent portion of the blank material. Then, for example, compared with the case where both wall surfaces are formed parallel to the circumferential direction of the molding surface, the effect of restricting the blank material from being drawn into the molding surface side is enhanced, and the end of the blank material is held more securely. can do.

  As described above, according to the press molding die of the present invention, since the blank holder can be omitted, the manufacturing cost and driving energy of the die can be reduced, and the processing quality of press molding can be stabilized.

It is sectional drawing of a press molding die (die opening state). It is sectional drawing of a press molding die (state which hold | maintained the edge part of a blank material). It is sectional drawing to which the edge part vicinity of the blank material of FIG. 2 was expanded. It is sectional drawing of the horizontal direction in the XX line of FIG. It is sectional drawing of a press-molding metal mold (during an overhang molding). It is sectional drawing to which the edge part vicinity of the blank material of FIG. 5 was expanded. It is sectional drawing of a press molding die (clamping state). It is sectional drawing to which the edge part vicinity of the blank material of FIG. 7 was expanded. It is sectional drawing of the press molding die which concerns on other embodiment. It is sectional drawing of the conventional press molding die (before stretch forming). It is sectional drawing of the conventional press molding die (clamping state).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a press molding die 1 according to an embodiment of the present invention. This press mold 1 is a mold used for overhang molding, for example, for molding a door outer of an automobile. The press-molding die 1 includes a punch 10, a die 20, and a drive mechanism (for example, a cylinder or a servo motor, not shown) that moves the die 20 closer to or away from the punch 10. In this embodiment, the case where the punch 10 is a fixed side and the die 20 is a moving side and the die 20 is moved up and down above the punch 10 is shown. In the following description, the left-right direction in FIG. 1 is referred to as “width direction”, and the center side (molding surface 11 side) of the mold in the width direction is “inside”, and the side away from the center of the mold is “outside”. "

  The punch 10 has a molding surface 11 for molding a design surface of a product (door outer). In the punch 10, a recess 12 is formed so as to surround the outer periphery of the molding surface 11, and in this embodiment, an annular recess 12 that surrounds the molding surface 11 over the entire periphery is formed. A contact surface 13 is formed over the entire periphery of the recess 12 (side away from the molding surface 11), and the contact surface 13 is disposed above the molding surface 11 in the illustrated example.

  The recess 12 includes a bottom surface 12a, an outer wall surface 12b, and an inner wall surface 12c. The bottom surface 12 a is formed substantially horizontally and is disposed below the molding surface 11. The outer wall surface 12b rises upward from the outer end of the bottom surface 12a, and rises vertically upward from the bottom surface 12a in this embodiment. The inner wall surface 12c rises upward from the inner end portion of the bottom surface 12a, and in this embodiment, the inner wall surface 12c rises inwardly from the bottom surface 12a. As shown in FIG. 4, the outer wall surface 12 b is formed in a corrugated shape in which peaks and valleys appear alternately in the circumferential direction of the molding surface 11 (vertical direction in the drawing). As for the waveform shape of the outer wall surface 12b, for example, the pitch P is set to about 10 to 20 mm, and the height difference H between the peak and valley is set to about 3 to 5 mm.

  As shown in FIG. 1, the die 20 has a pressing surface 21 that forms a predetermined shape by sandwiching the blank W between the forming surface 11 of the punch 10. The holding surface 21 is opposed to the molding surface 11 in the vertical direction and has a shape corresponding to the molding surface 11. In the die 20, a convex portion 22 is formed so as to surround the outer periphery of the pressing surface 21, and in the present embodiment, an annular convex portion 22 that surrounds the pressing surface 21 over the entire periphery is formed. A contact surface 23 is formed on the outer side of the convex portion, and the contact surface 23 is disposed above the holding surface 21 in the illustrated example.

  The convex portion 22 includes a tip surface 22 a, an outer wall surface 22 b, and an inner wall surface 22 c, and has a shape corresponding to the concave portion 12 of the punch 10. The front end surface 22a is formed substantially horizontally and faces the bottom surface 12a of the concave portion 12 of the punch 10 in the vertical direction. The outer wall surface 22b rises upward from the outer end portion of the distal end surface 22a, and rises vertically upward from the distal end surface 22a in the present embodiment. The inner wall surface 22c rises upward from the inner end portion of the distal end surface 22a, and in the present embodiment, the inner wall surface 22c rises upward and inward from the distal end surface 22a. The outer wall surface 22b is formed in a shape corresponding to the outer wall surface 12b of the recess 12, and is formed in a corrugated shape in which peaks and valleys appear alternately in the circumferential direction of the pressing surface 21 (see FIG. 4). The corrugated shapes of the outer wall surface 12b of the concave portion 12 and the outer wall surface 22b of the convex portion 22 are formed in the same phase and face each other through a minute gap.

  Below, the press molding method (extrusion molding method) using the press molding die 1 of the said structure is demonstrated.

  First, as shown in FIG. 1, the blank material W is disposed between the punch 10 and the die 20 in a state where the die 20 is separated from the punch 10 (that is, the die 20 is raised). In the illustrated example, the blank material W is placed on the contact surface 13 formed at the outer end of the punch 10.

  Next, as shown in FIG. 2, the die 20 is lowered and the convex portion 22 of the die 20 is inserted into the concave portion 12 of the punch 10 from above. Thereby, as shown in an enlarged view in FIG. 3, the blank material W is pressed from above by the tip surface 22 a of the convex portion 22, and the corner portion 22 d outside the convex portion 22 and the outer wall surface 12 b of the concave portion 12 are The end portion of the blank W is bent. When the bent portion W1 of the blank material W is wound around the corner portion 22d of the convex portion 22, the drawing of the blank material W into the inside is restricted. A region W2 outside the bent portion W1 of the blank W is sandwiched between the outer wall surface 12b of the concave portion 12 and the outer wall surface 22b of the convex portion 22, and rises upward. In the present embodiment, as shown in FIG. 4, both wall surfaces 12 b and 22 b are formed in the same phase corrugated shape, and the blank material W is sandwiched between them to ensure that the blank material W is drawn into the inside. Can be regulated. At this time, if the minute gap between the outer wall surface 22b of the convex portion 22 and the outer wall surface 12b of the concave portion 12 is too large, the effect of holding the blank material W cannot be obtained, and if it is too small, the blank material W is cut. Therefore, the thickness is set to be equal to or slightly smaller than the thickness of the blank material. For example, in the case of processing a blank material W having a thickness of 0.6 mm, the minute gap between the wall surfaces 12b and 22b is set to about 0.55 to 0.6 mm. Further, as shown in FIG. 3, the blank material W can be reliably prevented from being cut by forming the outer corner portion 22 d of the convex portion 22 into a rounded curved surface.

  When the die 20 is further lowered, the convex portion 22 is further inserted into the concave portion 12 as shown in FIG. At this time, by pushing the blank material downward over the molding surface 11 at the tip surface 22a of the convex portion 22, the central portion W0 of the blank material W is pressed against the molding surface 11 and stretched. Specifically, as shown in an enlarged view in FIG. 6, a region inside the folded portion W1 of the blank material W while holding the folded portion W1 of the blank material W and the outer region W2 thereof by the convex portion 22 and the concave portion 12. (Pressed portion) W3 is pushed downward by the tip surface 22a of the convex portion 22. At this time, an inclined portion W4 is formed inside the pressed portion W3 of the blank material W due to a difference in height between the forming surface 11 and the tip surface 22a of the convex portion 22 through a gap in the width direction. . By pushing down the pressed portion W3 of the blank material W with the convex portion 22, the central portion W0 of the blank material W is pressed against the molding surface 11 and stretched while the inclined portion W4 is stretched.

  When the die 20 is further lowered, as shown in FIG. 7, the contact surface 23 of the die 20 contacts the contact surface 13 of the punch 10 and the clamping is completed. In this way, the central portion W0 of the blank W is stretched while being pressed against the molding surface 11 of the punch 10 to be plastically deformed, and the central portion W0 is sandwiched between the molding surface 11 of the punch 10 and the pressing surface 21 of the die 20. Thus, the blank material W is formed into a predetermined shape. At this time, the end portions (W1 to W4) of the blank W are sandwiched between the concave portion 12 of the punch 10 and the convex portion 22 of the die 20.

  Thereafter, the die 20 is raised and the molded product is taken out from the mold (not shown). When the mold is opened, a vacuum state is instantaneously formed between the punch 10 and the die 20. At this time, for example, when the blank holder 102 is provided as shown in FIG. 11, a gap S is formed between the punch 103 and the blank holder 102. There is a risk of intrusion. Intrusion of foreign matter can be prevented by providing a filter in the gap S. However, since the blank holder 102 is movable with respect to the punch 103 and the gap S is provided on the entire periphery of the punch 103, a filter is provided in the gap S. It is difficult to provide Therefore, by eliminating the blank holder as in the present embodiment, the gap S as shown in FIG. 11 is not formed, and there is no possibility of foreign matter entering. In this case, in order to release the vacuum state between the punch 10 and the die 20 at an early stage, a through hole 14 that penetrates the punch 10 and has one end opened on the molding surface 11 as shown in FIG. Good. In this case, it is preferable to provide a filter (not shown) in order to prevent foreign matter from entering through the through hole 14. Such a through hole may be provided in the die 20.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the contact surface 13 is provided above the molding surface 11. However, the present invention is not limited to this. For example, as shown in FIG. May also be arranged below. According to this press-molding die 1 ′, since the convex portion 22 contacts the blank material W before being inserted into the concave portion 12, the convex portion 22 and the molding surface 11 are slightly bent after the blank material is curved. 22 is inserted into the recess 12 to hold the end of the blank. On the other hand, if the contact surface 13 is arranged above the molding surface as in the above embodiment, the blank material W is formed on the molding surface 11 after the end of the blank material W is held by the convex portions 22 and the concave portions 12. It is pressed and stretched.

  Thus, the timing which hold | maintains the edge part of the blank material W can be arbitrarily set by adjusting the relative height of the contact surface 13 and the molding surface 11. FIG. That is, when the amount of deformation by press molding is large (for example, when the curvature of the molding surface 11 is relatively large as shown in FIG. 9), the contact surface 13 is provided below the molding surface 11, and the blank material is provided to some extent. By holding the end portion after the deformation, the material can be molded without breaking. On the other hand, when the amount of deformation by press molding is small (for example, when the curvature of the molding surface 11 is relatively small as shown in FIG. 1), the contact surface 13 is provided above the molding surface 11, and the blank W By holding the end and then pressing the molding surface 11, the material can be sufficiently stretched to obtain a good design surface. Moreover, when it is desired to vary the deformation amount and the stretching amount of the blank material W depending on the location, the relative heights of the contact surface 13 and the molding surface 11 may be varied, for example, in the circumferential direction of the molding surface 11. .

  In addition, the press mold as described above is not limited to the case where the bending portion W1 formed at the end portion of the blank material W completely restricts the drawing of the end portion to the design surface side, but via the bending portion W1. The end may be slightly allowed to flow into the design surface side. Even in this case, the blank material W is stretched to the outside and is formed into a predetermined shape by preventing the material from being pulled in by the bent portion W1.

  In the above embodiment, the concave portion 12 formed in the punch 10 and the convex portion 22 formed in the die 20 are formed in an annular shape so as to surround the molding surface 11 over the entire circumference. It is not necessary for the convex portion 22 to be continuous over the entire circumference. For example, the concave portion or the convex portion may be divided in the vicinity of the corner of the mold.

DESCRIPTION OF SYMBOLS 1 Press molding die 10 Punch 11 Molding surface 12 Recess 13 Contact surface 20 Die 21 Holding surface 22 Projection portion 23 Contact surface W Blank material

Claims (1)

A press-molding die used for overhang molding, which includes a punch having a molding surface and a die provided so as to be relatively close to or away from the punch, and stretches and shapes a blank material against the molding surface. There,
A punch is formed with a recess so as to surround the outer periphery of the molding surface, and a die is formed with a protrusion inserted into the recess,
A holding mechanism that folds and holds an end portion of the blank material at the convex portion and the concave portion by inserting the convex portion into the concave portion with the die and the punch relatively approached, and the holding member among the blank materials. A stretch mechanism that stretches while pressing the blank material against the molding surface by pressing the inner region of the bent portion by the mechanism into the concave portion by the convex portion ; and
With the region outside the bent portion of the blank material sandwiched between the convex portion and the concave portion, the die and the punch are relatively approached to stretch the blank material,
On the wall surface of the convex portion that sandwiches the outer region of the bent portion of the blank material and the wall surface of the concave portion that opposes the same, peaks and valleys appear alternately along the circumferential direction of the molding surface. Press mold with phase waveform .

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