JP4932423B2 - Press working apparatus and press working method - Google Patents

Description

  The present invention relates to a pressing apparatus and a pressing method for pressing a molded product.

Conventionally, a member having a curved surface, such as a bonnet or a roof panel, is used in an automobile. The member having such a curved surface is formed, for example, by pressing a plate-like workpiece with an upper mold and a lower mold having a mold surface based on the surface shape of the molded product. Specifically, it is formed by pressing with an upper mold and a lower mold in a state where the periphery of the work is held by a holder (see Patent Document 1).
JP-A-2002-224758

  However, spring back may occur in the press work as described above. Springback is a phenomenon in which a plate-like workpiece is deformed by applying a force, and when the force applied to the workpiece is released, the plate is slightly restored to its original shape by an elastic recovery force.

  When such a springback occurs, the shape freezing property decreases, and therefore, the molding surfaces of the upper mold and the lower mold need to have a curvature larger than the curvature of a desired molded product in view of the springback. As a result, it takes time to manufacture the mold, which may increase the manufacturing cost.

  An object of this invention is to provide the press processing apparatus and press processing method which can reduce a spring back.

  The press working apparatus of the present invention is a press working apparatus for press-working a work, and includes a first die and a second die that are arranged with the work sandwiched therebetween and press-mold the work, and the first die. Control means for advancing and retreating with respect to the second mold, and the control means raises the first mold after drawing the workpiece by causing the first mold to reach a bottom dead center. And then let the first mold reach the bottom dead center again.

  According to this invention, after the first die reaches the bottom dead center and the workpiece is drawn, the first die is raised, and then the first die again reaches the bottom dead center. Therefore, the work is pressed again with the first mold and the work is sufficiently adapted to the first mold and the second mold, so that the spring back can be reduced.

  In this case, the apparatus further comprises a holder for holding the workpiece, and the control means holds the workpiece with the holder while the first die reaches the bottom dead center and the workpiece is drawn. It is preferred to release the holder while raising the mold of 1 and then reaching again bottom dead center.

  According to the present invention, since the holder is released while the first die is raised to reach the bottom dead center again, the tension by the holder can be prevented from acting on the workpiece, and the spring back can be reliably reduced. .

  In this case, it is preferable that the control means repeats a cycle in which the first mold is raised and then the first mold reaches the bottom dead center again a plurality of times.

  According to the present invention, the cycle in which the first mold is raised and then the first mold is again reached to the bottom dead center is repeated a plurality of times, so that the workpiece is adapted to the mold a plurality of times. Spring back can be further reduced.

  The press working method of the present invention is a press working method for pressing a workpiece by moving a first die forward and backward with respect to a second die, and the workpiece is moved by causing the first die to reach a bottom dead center. A first drawing step of drawing, and a second molding step of raising the first die and then reaching the bottom dead center again.

  According to the present invention, in the first draw step, the first die is made to reach bottom dead center and the workpiece is drawn, and then in the second forming step, the first die is raised, and then the first die Let the mold reach the bottom dead center again. Therefore, the work is pressed again with the first mold and the work is sufficiently adapted to the first mold and the second mold, so that the spring back can be reduced.

  In this case, it is preferable that a wrinkle holding force is applied to the workpiece in the first draw step, and a wrinkle holding force of the workpiece is released in the second molding step.

  According to the present invention, the wrinkle holding force of the work is released while the first mold is raised and again reaches the bottom dead center, so that the tension is prevented from acting on the work and the spring back is surely secured. Can be reduced.

  In this case, it is preferable to repeat the second molding step.

  According to this invention, the first mold is raised, and then the second molding step for allowing the first mold to reach the bottom dead center again is repeated a plurality of times, so that the workpiece is adapted to the mold a plurality of times. As a result, springback can be further reduced.

  According to the present invention, after the first die reaches the bottom dead center and the workpiece is drawn, the first die is raised, and then the first die reaches the bottom dead center again. Therefore, the work is pressed again with the first mold and the work is sufficiently adapted to the first mold and the second mold, so that the spring back can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a press working apparatus 10 according to an embodiment of the present invention.

  The press working apparatus 10 includes a lower mold mechanism 20 having a lower mold 52 as a second mold disposed below the steel plate 12 as a workpiece, and an upper mold as a first mold with respect to the lower mold 52. And an upper mold mechanism 18 for moving 38 close and away, and a control apparatus 16 for controlling the lower mold mechanism 20 and the upper mold mechanism 18.

  The upper mold mechanism 18 includes a servo motor 24, a reduction gear 26 that is rotationally driven by the servo motor 24, a rotary plate 28 that is rotationally driven by the reduction gear 26 with a large torque, and an upper end on the side surface of the rotary plate 28. The part has a connecting rod 30 that is pivotally supported.

  The servo motor 24 is, for example, an AC type, and has high responsiveness and small torque unevenness. The shaft rotation position of the servo motor 24 is detected by an encoder (not shown), and the servo motor is feedback-controlled based on the detected shaft rotation position.

  The upper mold mechanism 18 further includes a slider 32 pivotally supported on the lower end of the connecting rod 30 and an upper mold 38 provided on the lower surface of the slider 32.

  The upper die 38 is pressed by sandwiching the steel plate 12 together with the lower die 52, and a die surface (molding surface) 38a for contacting the upper surface of the steel plate 12 is provided on the lower surface. The upper mold 38 is a concave curved surface. Also. An annular holder 40 slightly protrudes around the upper mold 38. Therefore, the holder 40 comes into contact with the steel plate 12 ahead of the mold surface 38a. The front end surface of the holder 40 is set to a horizontal plane.

  The lower mold mechanism 20 includes a fixed base 50 that serves as a base, a lower mold 52 provided on the upper part of the fixed base 50, an annular blank holder 54 that supports the periphery of the steel plate 12, and the blank holder 54 that moves up and down. A die cushion mechanism 56.

  The lower mold 52 is pressed by pressing the steel plate 12 together with the upper mold 38, and a mold surface (molding surface) 52a for contacting the lower surface of the steel plate 12 is provided on the upper surface. The mold surface 52a has a shape corresponding to the mold surface 38a, here, a bulged curved surface.

  The blank holder 54 is provided at a position facing the holder 40 and sandwiches the end portion of the steel plate 12 together with the holder 40 in order to prevent wrinkles and displacement when the steel plate 12 is pressed.

  The die cushion mechanism 56 includes a plurality of pins 60 that pass through the fixing base 50 and the lower mold 52 from below and are fixed to the lower portion of the blank holder 54, and a hydraulic lifting mechanism (not shown) that lifts and lowers the pins 60. Have

  The lifting mechanism includes a hydraulic cylinder (not shown) connected to the pin 60 and a servo device (not shown) that drives the hydraulic cylinder. This servo device is connected to the control device 16, thereby pressing the peripheral portion of the steel plate 12 with an appropriate pressure by the blank holder 54 together with the holder 40 while performing a predetermined pressure control to suppress wrinkles. be able to.

  The control device 16 rotationally drives the servo motor 24 to move the upper die 38 forward and backward relative to the lower die 52 and drives the die cushion mechanism 56 to raise and lower the blank holder 54.

  A procedure for processing the steel plate 12 as a workpiece using the above press working apparatus 10 will be described with reference to the flowchart of FIG. 2 and the cross-sectional views of FIGS.

  First, in step S1, initial setting is performed. That is, as shown in FIG. 3, the blank holder 54 is raised to a predetermined position, and the blank steel plate 12 is supported by the blank holder 54. The upper die 38 is raised to the top dead center. In step S2, under the action of the control device 16, the servo motor 24 is rotationally driven to lower the slider 32.

When the slider 32 is lowered to some extent, as shown in FIG. 4, the holder 40 comes into contact with the upper surface of the steel plate 12, and the steel plate 12 is sandwiched between the holder 40 and the blank holder 54.
From this point, as shown in FIG. 5, the blank holder 54 is lowered under the action of the control device 16 (step S3). Specifically, under the action of the control device 16, the blank holder 54 generates an appropriate force so that the lower surface of the steel plate 12 appears to be pressed, and pressure control is performed so as to descend while securely holding the steel plate 12. I do. That is, the blank holder 54 is pressed through the steel plate 12 by the holder 40 and is pressed down while applying an appropriate pressure to the steel plate 12 (hereinafter, this pressure is referred to as a wrinkle pressing force). As a result, the steel sheet 12 descends while the peripheral portion is held (clamped) by the holder 40 and the blank holder 54 and is gradually drawn into a product shape by the upper mold 38 and the lower mold 52.

In step S4, as shown in FIG. 6, the control device 16 causes the position of the slider 32 to reach the bottom dead center (that is, the lowest point during one stroke of the upper mold 38).
In step S5, the blank holder 54 is lowered under the action of the control device 16 to release the wrinkle pressing force. In step S6, the servo motor 24 is rotationally driven under the action of the control device 16 as shown in FIG. Then, the slider 32 is raised to a predetermined position.

  In step S7, under the action of the control device 16, the servo motor 24 is rotationally driven to lower the slider 32 at a predetermined position, and in step S8, the slider 32 reaches the bottom dead center as shown in FIG. And molding again.

  In step S9, the servo motor 24 is rotationally driven under the action of the control device 16 to raise the slider 32 to the panel transport position. In step S10, it is confirmed whether or not the position of the slider 32 has reached the panel transport position. If it has reached, the process proceeds to step S11, and if not reached, the slider 32 continues to rise.

  In step S <b> 11, the blank holder 54 is raised under the action of the control device 16. As a result, the blank holder 54 rises slightly later than the slider 32. In step S12, the blank holder 54 is raised to the panel transport position under the action of the control device 16. In step S <b> 13, the ascent of the blank holder 54 is temporarily stopped, and the pressed steel plate 12 is transported to a next process (for example, trim processing process) station by a predetermined transport unit.

  In step S14, the control device 16 raises the blank holder 54 again to reach the blank holder 54 to the processing standby position. In step S15, the unprocessed steel plate 12 is placed at a predetermined position. During this time, the slider 32 continues to rise. In step S16, the control device 16 causes the slider 32 to reach the top dead center.

  Next, the operation of the above press working apparatus 10 will be described with reference to FIGS. 9A and 9B with a timing chart. In FIGS. 9A and 9B, the step numbers of the above processes are given to the corresponding positions on the horizontal axis (time t).

As shown in FIG. 9A, the position X of the slider 32 first descends from the top dead center X1 and reaches the bottom dead center X0 (steps S1 to S4). Here, the steel plate 12 is drawn while the position X of the slider 32 is from X1 to bottom dead center 0.
Thereafter, the slider 32 moves up to the predetermined position Xp (steps S5 and S6), then lowers again to reach the bottom dead center X0, and is molded again (steps S7 and S8).

  As shown in FIG. 9B, the die cushion pressure P is 0 during the period from step S1 to step S3. In step S3, since the steel plate 12 is held between the holder 40 and the blank holder 54, the die cushion pressure P becomes P1, and the pressure P1 remains until the blank holder is lowered in step S5. Thereafter, the die cushion pressure P becomes zero.

According to this embodiment, there are the following effects.
(1) After the upper die 38 reaches the bottom dead center and the steel plate 12 is drawn (step S4), the upper die 38 is raised (steps S5 and S6), and then the upper die 38 is set to the bottom dead center again. Reach (steps S7, S8). Therefore, the steel plate 12 is pressed again by the upper die 38 and the steel plate 12 is sufficiently fitted to the upper die 38 and the lower die 52, so that the spring back can be reduced.

  (2) Since the holder 40 is released during the period in which the upper die 38 is raised and the upper die 38 reaches the bottom dead center again (steps S5 to S8), the tension applied by the holder 40 is prevented from acting on the steel plate 12. Thus, the spring back can be reliably reduced.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in this embodiment, the upper mold 38 is raised and then the upper mold 38 is again reached once at the bottom dead center. However, the present invention is not limited to this, and this cycle may be repeated a plurality of times. Good. In this way, the steel plate 12 is adapted to the upper die 38 and the lower die 52 a plurality of times, and the spring back can be further reduced.

It is a figure which shows schematic structure of the press work apparatus concerning one Embodiment of this invention. It is a flowchart which shows operation | movement of the said press work apparatus. It is a fragmentary sectional view which shows the initial state of the said press work apparatus. It is a fragmentary sectional view which shows the state which clamped the steel plate with the holder of the said press work apparatus. It is a fragmentary sectional view which shows the state which lowered | hung the slider of the said press work apparatus. It is a fragmentary sectional view which shows the state which lowered | hung the slider of the said press work apparatus to the bottom dead center. It is a fragmentary sectional view which shows the state which raised the slider of the said press work apparatus to the predetermined position. It is a fragmentary sectional view which shows the state which lowered | hung the slider of the said press work apparatus to the bottom dead center again. (A) is a timing chart which shows the displacement of a slider, (B) is a timing chart which shows the change of die-cushion pressure.

Explanation of symbols

10 Press working device 12 Steel plate (work)
16 Control device (control means)
38 Upper mold (first mold)
40 Holder 52 Lower mold (second mold)
54 Blank holder (holder)

Claims (4)

A press processing apparatus for press-working a workpiece,
A first mold and a second mold that are arranged with the workpiece sandwiched therebetween and press-mold the workpiece;
A holder for clamping the workpiece;
Control means for advancing and retracting the first mold relative to the second mold,
The control means causes the first die to reach bottom dead center and draws the workpiece, then raises the first die, and then causes the first die to reach bottom dead center again. ,
While the workpiece is drawn with the first die reaching the bottom dead center, the holder is clamped with the holder, the first die is raised, and then the bottom dead center is reached again. The press working apparatus characterized by releasing . In the press processing apparatus of Claim 1 ,
The press processing apparatus, wherein the control means repeats a cycle of raising the first die and then causing the first die to reach the bottom dead center a plurality of times. A pressing method for pressing a workpiece by moving a first die forward and backward with respect to a second die,
A first drawing step of drawing the workpiece by causing the first die to reach a bottom dead center;
A second molding step of raising the first mold and then causing the first mold to reach bottom dead center again ,
In the first draw step, a pressing force is applied to the workpiece, and in the second forming step, the pressing force of the workpiece is released . In the press processing method of Claim 3 ,
A press working method, wherein the second forming step is repeated.

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