JP2012218061A - Press molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press molding apparatus capable of molding seat face shape with a deep step in one stroke while suppressing the occurrence of a molding failure.SOLUTION: The press molding apparatus includes: a punch 21 having a punch body 213, and a movable punch 211 built in the punch body 213 and movable from a projecting position into a recessed position with respect to a molding surface 213a of the punch body 213; and a die 31 having a molding surface shaped to correspond to the molding surface 21a of the punch 21 when the movable punch 211 is in the most recessed position with respect to the molding surface 213a of the punch body 213. A steel sheet 10 is preliminarily worked into shape to correspond to the molding surface 21a of the punch 21 when the movable punch 211 is in the projecting position by lowering a lower blank holder 23 to press the steel sheet 10 to the punch 21, and then the die 31 is lowered and brought close to the punch 21 to draw the steel sheet 10 while moving the movable punch 211 into the most recessed position with respect to the molding surface 213a of the punch body 213.

Description

  The present invention relates to a press molding apparatus. More specifically, the present invention relates to a press forming apparatus that performs a drawing process on a workpiece.

  2. Description of the Related Art Conventionally, a stepped shape (hereinafter referred to as “seat surface shape”) in which a hole is provided in a recess, such as a component mounting seat surface, is formed by a press molding apparatus.

  For example, a press forming apparatus has been proposed in which a recess is formed in a workpiece by drawing and then a hole is formed in the recess by punching (see Patent Document 1).

Japanese Utility Model Publication No. 59-165725

  However, in the technique of Patent Document 1, since the drawing is performed before the hole punching that can give a degree of freedom to the elongation of the material, there is a limit to the elongation of the material during the drawing. For this reason, when molding of a seating surface shape with a deep step, molding defects such as cracks may occur.

  In order to avoid molding defects as described above, when drawing is performed with a plurality of strokes, it is necessary to change the molding die for each process, and the molding accuracy decreases. In addition, the processing cost increases due to an increase in the number of strokes and a change in the molding die.

  The present invention has been made in view of the above, and an object of the present invention is to provide a press molding apparatus that can form a seat surface shape with a deep step with one stroke while suppressing the occurrence of molding defects.

  In order to achieve the above object, a press forming apparatus (for example, a press forming apparatus 1 described later) according to the present invention is a press forming apparatus for drawing a workpiece (for example, a steel sheet 10 described later), and includes a punch body. (For example, a punch body 213 which will be described later) and a movable punch which is built in the punch body and is movable from a position protruding from a molding surface of the punch body (for example, a molding surface 213a described later) to a recessed position. For example, a punch provided with a movable punch 211 described later (for example, punch 21 described later), and blank holders (for example, a lower blank holder 23 and an upper blank holder 33 described later) for sandwiching the end of the workpiece. The punch forming surface when the movable punch is located in the most recessed position with respect to the punch body forming surface (example) For example, a die (e.g., a die 31 described later) having a molding surface (e.g., a molding surface 31a described later) having a shape corresponding to a molding surface 21a described later, and a control means (e.g., the blank holder and the die are moved up and down). And a control device 40 to be described later, wherein the control means lowers the blank holder and presses the workpiece against the punch, whereby the movable punch protrudes from the molding surface of the punch body. The workpiece is preliminarily processed into a shape corresponding to the molding surface of the punch when the die is lowered and brought close to the punch, so that the movable punch can be moved to the molding surface of the punch body most. The workpiece is drawn while being moved to a recessed position.

According to the present invention, when drawing a workpiece, first, the blank holder holding the end portion of the workpiece is lowered to press the workpiece against the punch. Thereby, a workpiece | work is shape | molded in the shape corresponding to the shaping | molding surface of a punch when the movable punch exists in the position which protruded with respect to the shaping | molding surface of the punch main body. That is, preliminary processing for once forming a convex portion on the workpiece is performed.
Then, the movable punch is moved to the most recessed position with respect to the molding surface of the punch body by lowering the die and bringing the die close to the punch. Thereby, the drawing of the workpiece is performed while the convex portion formed by the preliminary processing is conversely formed into the concave portion.
Thus, according to the present invention, after forming the convex portion once by preliminary processing, the drawing is performed while forming the convex portion into the concave portion, so that the material can be sufficiently stretched. For this reason, molding defects such as cracks do not occur even when a deep stepped bearing surface shape is molded. Moreover, since preliminary processing and drawing are performed with a single stroke, high molding accuracy can be obtained, and processing costs can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the press molding apparatus which can shape | mold the seat surface shape of a deep level | step difference with one stroke can be provided, suppressing generation | occurrence | production of a molding defect.

It is a figure for demonstrating the drawing processing which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the press molding apparatus which concerns on the said embodiment. It is a longitudinal cross-sectional view of the press molding apparatus which performs the preliminary process which concerns on the said embodiment. It is a longitudinal cross-sectional view of the press molding apparatus which performs the drawing process which concerns on the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Drawing according to an embodiment of the present invention is performed by a press molding apparatus 1 described later. As shown in FIG. 1, the drawing process of the present embodiment is performed by performing a preliminary process for once forming a convex part on a steel plate 10 as a work, and then forming the convex part formed into a concave part on the contrary. The seat surface shape is formed.

FIG. 2 is a longitudinal sectional view of a press forming apparatus according to an embodiment of the present invention.
The press forming apparatus 1 controls a lower mold mechanism 20 disposed on the lower side of the steel plate 10 as a workpiece, an upper mold mechanism 30 disposed on the upper side of the steel plate 10, and the lower mold mechanism 20 and the upper mold mechanism 30. And a control device 40 as control means.
The lower mold mechanism 20 and the upper mold mechanism 30 are disposed to face each other with the steel plate 10 interposed therebetween.

  The lower die mechanism 20 includes a fixed base 27, a punch 21 provided on the upper surface of the base 27, an annular lower blank holder 23 provided around the punch 21, and the lower blank holder 23 as a punch 21. A die cushion mechanism 25 that moves up and down relatively.

The punch 21 supports the steel plate 10 at the time of forming, and draws the steel plate 10 with a die 31 described later. Formed on the upper surface of the punch 21 is a molding surface 21 a that contacts the lower surface of the steel plate 10.
The punch 21 includes an annular movable punch 211 and an annular punch body 213 fixed to the upper surface of the base 27 and provided around the movable punch 211.

The movable punch 211 is built in the punch body 213. The movable punch 211 has an annular large-diameter portion 211c having a large outer diameter and an annular small-diameter portion 211b provided on the upper end side thereof and having a small outer diameter. The annular large diameter portion 211c and the annular small diameter portion 211b have the same inner diameter.
The movable punch 211 can be moved up and down relatively with respect to the punch body 213 by a movable punch lifting mechanism 215 provided on the upper surface of the base 27. More specifically, the movable punch 211 has a position recessed from a position protruding relative to the upper surface (molding surface) 213a of the punch body 213 (that is, the upper surface (molding surface) 211a of the annular small diameter portion 211b is the upper surface of the punch body 213). (Molding surface) It can move up and down from a position above 213a to a position below.
The upper edge of the annular small diameter portion 211b is chamfered to form a curved surface.

The punch main body 213 includes a main body portion 213c and a flange portion 213b that is provided around the annular small diameter portion 211b of the movable punch 211 and protrudes radially inward on the upper end side of the main body portion 213c. The above-described movable punch 211 is restricted from moving upward by the upper surface of the annular large-diameter portion 211c of the movable punch 211 coming into contact with the lower surface of the flange portion 213b of the punch body 213.
In addition, the upper end outer edge of the collar part 213b is chamfered and becomes a curved surface.

  The lower blank holder 23 has a horizontal upper surface, and sandwiches the end of the steel plate 10 together with an upper blank holder 33 described later. The lower blank holder 23 moves down together with the upper blank holder 33 during preliminary processing, and presses the sandwiched steel sheet 10 against the forming surface 21 a of the punch 21, thereby forming a convex portion on the steel sheet 10. In addition, wrinkles and misalignments are prevented during drawing.

  The die cushion mechanism 25 and the movable punch lifting mechanism 215 each include a hydraulic cylinder (not shown) connected to a pin (not shown) and a servo device (not shown) that drives the hydraulic cylinder. The servo device is connected to a control device 40 to be described later, whereby predetermined pressure control is performed.

  The upper mold mechanism 30 includes a base 35, a main lifting mechanism 37 that raises and lowers the base 35, a die 31 provided on the lower surface of the base 35, and an annular shape that is fixed to the lower surface of the base 35 and provided around the die 31. The upper blank holder 33 is provided.

  Formed on the lower surface of the die 31 is a forming surface 31 a that contacts the upper surface of the steel plate 10. The molding surface 31 a has a shape corresponding to the molding surface 21 a of the punch 21 when the movable punch 211 is at the most recessed position with respect to the upper surface (molding surface) 213 a of the punch body 213.

  The die 31 is provided coaxially with the center axis X of the movable punch 211 and the punch body 213 described above. The die 31 includes a columnar fixed die 311 fixed to the base 35, and an annular movable die 313 provided around the fixed die 311.

  The fixed die 311 has a large diameter part 311c and a small diameter part 311b provided on the lower end side thereof. The diameter of the large diameter portion 311c is set slightly smaller than the inner diameter of the flange portion 213b of the punch body 213 described above, and the diameter of the small diameter portion 311b is slightly smaller than the inner diameter of the annular small diameter portion 211b of the movable punch 211. Is set. The lower surface of the small diameter portion 311b is disposed so as to be positioned above the lower surface of the upper blank holder 33 described later. Further, a trim blade 311a is provided at the lower end edge of the small diameter portion 311b, and the small diameter portion 311b functions as a punch for forming a hole in the concave portion of the seating surface.

  The movable die 313 can be moved up and down relative to the fixed die 311 and the upper blank holder 33 by a sub-lifting mechanism 315 provided on the lower surface of the base portion 35. The lower surface of the movable die 313 is disposed so as to be positioned above the lower surface of the small diameter portion 311b.

  The lower surface of the upper blank holder 33 is horizontal, and sandwiches the end portion of the steel plate 10 together with the lower blank holder 23. The upper blank holder 33 is lowered together with the lower blank holder 23 at the time of preliminary processing and presses the sandwiched steel plate 10 against the punch 21 to form a convex portion on the steel plate 10. In addition, wrinkles and misalignments are prevented during drawing.

  The main lifting mechanism 37 and the sub lifting mechanism 315 each include a hydraulic cylinder (not shown) connected to a pin (not shown) and a servo device (not shown) that drives the hydraulic cylinder. The servo device is connected to a control device 40 to be described later, whereby predetermined pressure control is performed.

  The control device 40 is electrically connected to the die cushion mechanism 25, the movable punch lifting mechanism 215, the main lifting mechanism 37, and the sub lifting mechanism 315, and controls these mechanisms.

Operation | movement of the press molding apparatus 1 provided with the above structures is demonstrated with reference to FIGS.
First, initial setting of the upper mold mechanism 30 and the lower mold mechanism 20 is performed.
About the upper mold | type mechanism 30, the main raising / lowering mechanism 37 is driven by the control apparatus 40, and the die | dye 31 and the upper side blank holder 33 are raised to a top dead center. Further, the control device 40 drives the sub elevating mechanism 315 so that the lower surface of the movable die 313 is higher than the lower surface of the small-diameter portion 311b of the fixed die 311 according to the depth of the step of the seating surface shape to be molded. The movable die 313 is raised with respect to the fixed die 311.
With respect to the lower mold mechanism 20, the control device 40 is configured such that the upper surface (molding surface) 211a of the annular small diameter portion 211b of the movable punch 211 is positioned above the upper surface (molding surface) 213a of the flange portion 213b of the punch body 213. Thus, the movable punch lifting mechanism 215 is driven to raise the movable punch 211. Specifically, the upper surface of the annular large diameter portion 211c of the movable punch 211 contacts the lower surface of the flange portion 213b of the punch body 213 according to the depth of the stepped shape of the seating surface to be molded, for example, as shown in FIG. The movable punch 211 is raised to the position where it comes into contact, that is, the position that protrudes most with respect to the upper surface (molding surface) 213a of the punch body 213. Further, the die cushion mechanism 25 is driven by the control device 40 so that the upper surface of the lower blank holder 23 is positioned above the upper surface (molding surface) 211a of the annular small diameter portion 211b of the movable punch 211, so that the lower blank holder 23 is driven. The holder 23 is raised.

Next, the steel plate 10 is set in the press forming apparatus 1.
Specifically, the raw steel plate 10 is supported on the upper surface of the lower blank holder 23, and in this state, the main lifting mechanism 37 is driven by the control device 40 to lower the die 31 and the upper blank holder 33. Then, the lower surface of the upper blank holder 33 comes into contact with the upper surface of the steel plate 10, and the end portion of the steel plate 10 is sandwiched between the lower blank holder 23 and the upper blank holder 33 as shown in FIG. 2.

Next, preliminary processing is performed on the steel plate 10.
Specifically, as shown in FIG. 3, the main lifting mechanism 37 is driven by the control device 40 to further lower the die 31 and the upper blank holder 33. More specifically, the die cushion mechanism 25 is driven by the control device 40 while maintaining the lowering of the die 31 and the upper blank holder 33, and the end of the steel plate 10 is appropriately adjusted by the lower blank holder 23 and the upper blank holder 33. The lower blank holder 23 is lowered so as to be held with a sufficient pressure. Then, the lower surface of the sandwiched steel plate 10 contacts and is pressed against the forming surface 21a of the punch 21, and the steel plate 10 is preliminarily processed into a shape corresponding to the forming surface 21a of the punch 21. As a result, as shown in FIG. 3, the steel plate 10 is convexly extended upward and is once formed into a shape having a convex portion.
At this time, since the trim blade 311a is provided at the lower end edge of the small-diameter portion 311b of the fixed die 311, the lower surface of the small-diameter portion 311b comes into contact with the convex portion of the steel plate 10 as shown in FIG. Thus, a part of the convex part is cut off, and a hole is formed in the convex part. This increases the degree of freedom of material elongation in the next drawing process.
In addition, since the upper end outer edge of the annular small diameter portion 211b of the movable punch 211 and the upper end outer edge of the flange portion 213b of the punch main body 213 are chamfered, it is possible to suppress damage to the lower surface of the steel plate 10 during preliminary processing. The

Next, the steel plate 10 is drawn.
Specifically, as shown in FIG. 4, the main lifting mechanism 37 is driven by the control device 40 to further lower the die 31 and the upper blank holder 33. At this time, since the lower surface of the fixed die 311 is in contact with the upper surface of the steel plate 10, the control device 40 drives the sub elevating mechanism 315 so that the steel plate 10 is pressed with an appropriate pressure by the fixed die 311 and the punch body 213. Then, the movable die 313 is raised.
Then, the movable punch 211 was pushed downward by the fixed die 311 and descended while being sandwiched between the large diameter portion 311c of the fixed die 311, the annular small diameter portion 211b of the movable punch 211 and the flange portion 213b of the punch body 213. The portion (the flange portion of the molded product) is drawn, and the convex portion once formed on the steel plate 10 is conversely formed into the concave portion. When the movable punch 211 is pushed downward by the fixed die 311 and is lowered, the movable punch lifting mechanism 215 is driven by the control device 40, and the upper surface of the annular small diameter portion 211 b of the movable punch 211 and the fixed die 311. The movable punch 211 is lowered so that the flange portion is appropriately drawn with the lower surface of the large diameter portion 311c. Thereby, the steel plate 10 is shape | molded by the desired seat surface shape.

  Thereafter, the main lifting mechanism 37 is driven by the control device 40 to raise the die 31 and the upper blank holder 33. Next, the die cushion mechanism 25 is driven by the control device 40, the lower blank holder 23 is raised, and the formed steel plate 10 is taken out.

According to the press molding apparatus 1 according to the present embodiment, the following effects are exhibited.
According to the present embodiment, when drawing the steel plate 10, first, the lower blank holder 23 and the upper blank holder 33 that sandwich the end portion of the steel plate 10 are lowered to press the steel plate 10 against the punch 21. . Thereby, the steel plate 10 is formed into a shape corresponding to the forming surface 21a of the punch 21 when the movable punch 211 is located at a position protruding from the forming surface 213a of the punch body 213. In other words, the steel plate 10 is preliminarily processed to temporarily form convex portions.
Thereafter, the die 31 is moved down to bring the die 31 close to the punch 21, whereby the movable punch 211 is moved to the most recessed position with respect to the molding surface 213 a of the punch body 213. Thereby, the drawing process of the steel plate 10 is performed while the convex part formed by the preliminary process is turned into the concave part.
Thus, according to this embodiment, after forming a convex part once by preliminary processing, drawing is performed while forming the convex part into a concave part, so that sufficient elongation of the material can be secured. For this reason, molding defects such as cracks do not occur even when a deep stepped bearing surface shape is molded. Moreover, since preliminary processing and drawing are performed with a single stroke, high molding accuracy can be obtained, and processing costs can be 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 the above embodiment, the small diameter portion 311b is provided on the lower end side of the fixed die 311. However, the present invention is not limited to this. When the hole is not formed in the seating surface, it is not necessary to provide the small diameter portion 311b, and the fixed die 311 may be integrated with the movable die 313 and fixed. In this case, since the hollow portion of the movable punch 211 is not necessary, the movable punch 221 may be a columnar shape instead of an annular shape.

DESCRIPTION OF SYMBOLS 1 ... Press molding apparatus 10 ... Steel plate (workpiece)
DESCRIPTION OF SYMBOLS 20 ... Lower mold mechanism 21 ... Punch 211 ... Movable punch 213 ... Punch main body 215 ... Movable punch raising / lowering mechanism 23 ... Lower blank holder (blank holder)
25 ... Die cushion mechanism 30 ... Upper die mechanism 31 ... Die 311 ... Fixed die 313 ... Movable die 315 ... Sub lift mechanism 33 ... Upper blank holder (blank holder)
37 ... Main lifting mechanism 40 ... Control device (control means)

Claims (1)

A press molding apparatus for drawing a workpiece.
A punch comprising: a punch body; and a movable punch built in the punch body and movable from a position protruding relative to a molding surface of the punch body to a recessed position;
A blank holder for clamping the end of the workpiece;
A die having a molding surface provided opposite to the punch and having a shape corresponding to the molding surface of the punch when the movable punch is at the most recessed position with respect to the molding surface of the punch body;
Control means for raising and lowering the blank holder and the die,
The control means lowers the blank holder and presses the workpiece against the punch, thereby corresponding to the punch forming surface when the movable punch is in a position protruding from the punch body forming surface. After pre-working the work into a shape, the work is drawn while moving the movable punch to the most recessed position with respect to the molding surface of the punch body by lowering the die and bringing it close to the punch. A press molding apparatus characterized by:

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