JP2003094119A - Press tool and press molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press tool and a press molding method which increase or decrease a crease restraining force in one forming process and further can increase or decrease the crease restraining force in each place, by devising a mold, instead of using an expensive pressing machine with a crease restraining force controller. SOLUTION: In a press tool comprising a punch 3, a die 1 and a crease restrainer 2, a pressure cylinder 5 is installed as a mechanism for generating the crease restraining force in addition to a cushion pin. The pressure cylinder 5 is set in the range of 0.5(dc+D)<L<=3(dc+D): Where dc: diameter of cushion pin, D: outer diameter of pressure cylinder, and L: center distance between the pressure cylinder and the nearest cushion pin. The pressure cylinder and crease restrainer can increase the crease restraining force in one forming process by touching in an optional stroke and commencing pressurization after commencing forming.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press-molding die and a press-molding method. More specifically, the wrinkle-holding force is increased / decreased in one molding process, and the wrinkle-holding force is increased / decreased at each place. The present invention relates to a press molding die and a molding method capable of performing the above.

[0002]

2. Description of the Related Art Conventionally, attempts have been made to suppress the occurrence of press molding defects by increasing or decreasing the wrinkle holding force in one molding process. For example, as disclosed in Japanese Unexamined Patent Publication No. 02-37922, increasing wrinkle holding force in one molding process prevents occurrence of body wrinkles, and is disclosed in Japanese Unexamined Patent Publication No. 9-38728. As described above, a molding method has been proposed in which breakage is avoided by reducing the wrinkle holding force in one molding process.

On the other hand, as an apparatus for increasing and decreasing the wrinkle holding force in one molding step as described above, Japanese Patent Laid-Open No. 10-
As disclosed in Japanese Patent No. 76323 and Japanese Utility Model Laid-Open No. 61-190316, a hydraulic pressure or pneumatic circuit composed of a control valve such as an electromagnetic proportional relief valve and a detection device for detecting the stroke position of the press slide and the wrinkle holding force are optional. A method of installing a control device that electrically controls the wrinkle holding force by the stroke is proposed.

[0004]

However, if the wrinkle holding force control device as described above is installed, there is a problem that the press machine is large and expensive. In addition, even if the press machine is prepared to be large and expensive, and it is good to newly manufacture it, a large-scale modification is required to assemble the wrinkle holding force control device to the already used press machine, It requires a long period of facility outage, which is almost impossible from a cost perspective. Further, the expensive wrinkle pressing force control device is not necessary for press molding of all the parts to be manufactured, and there is a high possibility that the investment efficiency will be extremely poor.

The present invention has been made in view of the above circumstances, and an object thereof is to perform one molding by devising a die without using an expensive press machine having the wrinkle holding force control device. An object of the present invention is to provide a press-molding die and a molding method capable of increasing / decreasing the wrinkle holding force during the process and further increasing / decreasing the wrinkle holding force at each place.

[0006]

In order to achieve the above object, in the invention of claim 1, in a press-molding die comprising a punch, a die and a wrinkle retainer, a mechanism other than a cushion pin is used as a mechanism for generating a wrinkle retaining force. Install the pressure cylinder within the range of 0.5 (dc + D) <L ≦ 3 (dc + D) (cushion pin diameter: dc, pressure cylinder outer diameter: D, between the pressure cylinder and the closest cushion pin center). Distance: L) The pressurizing cylinder and the wrinkle retainer make it possible to increase the wrinkle retaining force in one molding process by contacting at an arbitrary stroke after the start of molding and starting pressurization. According to a second aspect of the present invention, in order to achieve the above object, in a press-molding die including a punch, a die and a wrinkle retainer, a cylinder, which is a pressure generating portion of a hydraulic cam, is installed between the die and the wrinkle retainer. Install the cam pump outside the wrinkle holder and under the die, install a cylinder that pressurizes the hydraulic cam pump at a position facing the hydraulic cam pump of the die, and install it on the die at any stroke after the start of molding. When the pressurizing cylinder comes into contact with the pump, the cylinder between the die and the wrinkle presser starts pressurizing, so that the wrinkle holding force can be reduced in one molding process. According to the invention of claim 3, in order to achieve the above object, the mechanism of claim 1 or 2 is incorporated into one mold, and it is possible to increase or decrease the wrinkle holding force in one molding step. According to the invention of claim 4, in order to achieve the above object, the wrinkle retainer is divided, and the mechanism according to any one of claims 1 to 3 is incorporated into all or a part of the divided portions, so that wrinkles are formed at each place. It is possible to increase or decrease the pressing force. In order to achieve the above-mentioned object, the invention of claim 5 uses the press die according to any one of claims 1 to 4 to increase or decrease the wrinkle holding force in one molding step, and further The press forming method is characterized by increasing and decreasing the wrinkle holding force for each.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
First, the invention of claim 1 will be described with reference to FIG. 1, which is a schematic diagram of the concept. In FIG. 1, in the initial stage of molding, the work piece is sandwiched between the die 1 and the wrinkle retainer 2, and the wrinkle holding force applied to the work piece is applied by the cushion pin that is in contact with the wrinkle retainer below. . When the molding progresses and the wrinkle retainer 2 comes into contact with the pressurizing cylinder 5, the wrinkle retaining force increases to a value obtained by adding the force of the pressurizing cylinder to the force of the cushion pin. At this time, the timing for increasing the wrinkle holding force is to consider the height position of the wrinkle holding at the start and the end of molding and the height and stroke of the pressurizing cylinder 5 by inserting a spacer under the pressurizing cylinder 5, The installation position height of the pressurizing cylinder 5 is adjusted by a method such as forming a recess in the mold (the punch 3 in FIG. 1) and installing the pressurizing cylinder 5 in the recess. It can be arbitrarily set by adjusting the contact position of the presser 2. Furthermore, it is also possible to increase the wrinkle holding force in multiple stages by disposing a plurality of pressure cylinders 5 and changing the contact timings of these with the wrinkle holding member 2.

Further, the installation position on the plane perpendicular to the height direction of the pressure cylinder is set to 0.5 (dc + D) <L in order to avoid interference with the cushion pin, and the work piece is loaded by the wrinkle holding force. In order to prevent non-uniformity of the surface pressure, L is within the range of 3 (dc + D). Where dc
Is the diameter of the cushion pin, D is the outer diameter of the pressure cylinder,
L is the center distance between the pressure generator and the closest cushion pin. The degree of increase in the wrinkle holding force can be adjusted by adjusting the load capacity of the installed cylinder or by selecting the cylinder having the required pressurizing capacity.

Next, the invention of claim 2 will be described with reference to FIG. 2, which is a schematic diagram of the concept. In FIG. 2, in the initial stage of molding, the work piece is sandwiched between the die 1 and the wrinkle retainer 2, and the wrinkle holding force applied to the work piece is applied by the cushion pin that is in contact with the wrinkle retainer below. . When the molding progresses and the pressurizing cylinder 9 embedded in the die comes into contact with the pump portion 7 of the hydraulic cam, the cylinder portion 6 of the hydraulic cam exerts a force in a direction to widen the gap between the die 1 and the wrinkle retainer 2 to cause wrinkling. The pressing force decreases to the value obtained by subtracting the force applied by the pressurizing cylinder from the force applied by the cushion pin. At this time, the reduction timing of the wrinkle holding force is adjusted by adjusting the contact position between the pump portion 7 of the hydraulic cam and the pressurizing cylinder 9 embedded in the die 1.
It can be set arbitrarily. Further, it is also possible to reduce the wrinkle holding force in multiple stages by disposing a plurality of hydraulic cams and changing the contact timing between the pump portion 7 of each hydraulic cam and the pressurizing cylinder 9 embedded in the die 1. . The degree of reduction of the wrinkle pressing force is adjusted by adjusting the load capacity of the pressurizing cylinder 9 installed in the die 1 and the cross-sectional area ratio of the hydraulic chambers of the cylinder portion 6 of the hydraulic cam and the pump portion 7, or the required pressurizing force. This is possible by selecting a cylinder of capacity and a hydraulic cam having the required cross-sectional area ratio of the pump part and the cylinder part. Further, the installation position of the pump portion of the hydraulic cam is not essential in order to prevent uneven surface pressure, but it is preferable to be directly above the cushion pin as shown in FIG.

Next, the invention of claim 3 will be described.
By incorporating the mechanism according to claim 1 or 2 in one mold and shifting the timing of increase and decrease of the wrinkle holding force, the wrinkle holding force can be increased or decreased in one molding process. Furthermore, by incorporating two or more of either or both of the mechanisms of claims 1 and 2, it is possible to repeatedly increase and decrease the wrinkle presser.

Next, the invention of claim 4 will be described with reference to FIG. 3 which is a schematic diagram of the concept. FIG. 3 is a plan view of a 1/4 part of a mold for obtaining a molded part of a rectangular tube as viewed from a surface on which a material to be processed is placed on the mold before molding.
As shown in FIG. 3, the portion of the molded product of the wrinkle retainer 2 that is in contact with the work piece forming the vertical wall portion and the corner portion is divided. Then, by incorporating the mechanism according to any one of claims 1 to 3 into all or a part of the dividing portion,
It is possible to increase or decrease the wrinkle holding force for each place.
Of course, if a plurality of mechanisms according to claim 1 or 2 are incorporated in one divided portion, it is possible to increase, decrease, and increase or decrease the wrinkle holding force in multiple stages.

Next, the invention of claim 5 will be described.
By using the press die according to any one of claims 1 to 4, it becomes possible to provide a press molding method in which the wrinkle holding force is increased / decreased in one molding step, and further the wrinkle holding force is increased / decreased in each place. . As a result, it becomes possible to manufacture a molded part that cannot be achieved by the conventional molding method in which the wrinkle pressing force is constant. For example, the crease holding force is reduced before rupture to avoid rupture by promoting material inflow, the crease holding force is increased at the timing of wrinkle generation to avoid wrinkle generation, and the wrinkle holding force is applied immediately before the end of molding. It is possible to increase fracture resistance, avoid breakage, and eliminate shape freezing defects.

[0013]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 4 is a diagram showing a mold structure for obtaining the molded part shown in FIG. In FIG. 4, the portion of the molded product of the wrinkle retainer 2 that is in contact with the work piece forming the vertical wall portion and the corner portion is divided. At the corner, after the start of molding, the pressurizing cylinder 9 embedded in the die 1 comes into contact with the hydraulic pump 7 and the hydraulic cylinder 6 is pressed.
Has a mechanism that the wrinkle pressing force is reduced by starting the pressurization, and when the molding further proceeds, the pressurizing cylinder 5 comes into contact with the wrinkle pressing member 2 to start the pressurization and the wrinkle pressing force is increased. There is. On the other hand, the straight side portion has a mechanism in which the pressurizing cylinder 5 comes into contact with the wrinkle retainer 2 after the start of molding to start pressurization, and the wrinkle retaining force increases. By using such a mold, as shown in FIG. 6, it is possible to increase or decrease the wrinkle holding force in one molding process and change the change pattern of the wrinkle holding force at the corner portion and the straight side portion. It was From the viewpoint of improving moldability, the meaning of the example of FIG. 6 is as follows. For the corners, the initial wrinkle holding force is set higher in order to suppress the wrinkle generation, and then the wrinkle holding force is reduced to avoid breakage. After that, the wrinkle holding force is increased just before the bottom dead center to eliminate the shape freeze defect. on the other hand,
Regarding the straight side part, the wrinkle holding force is increased just before the bottom dead center in order to eliminate the shape-freezing defect.

[0014]

As described above, according to the present invention,
It is possible to perform molding with changing the wrinkle holding force during one molding process without using an expensive press molding device. as a result,
It becomes possible to mold high-tensile steel and aluminum, which are difficult molding materials, and the weight reduction of automobiles can be achieved by expanding the application of these materials.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the concept of the invention of claim 1.

FIG. 2 is a schematic diagram showing the concept of the invention of claim 2;

FIG. 3 is a schematic diagram showing the concept of the invention of claim 3;

FIG. 4 is a diagram showing a mold structure according to an embodiment of the present invention.

FIG. 5 is a diagram showing a molded product obtained in an example of the present invention.

FIG. 6 is a diagram showing a change pattern of the wrinkle holding force realized by the embodiment, where a is a change pattern of the wrinkle holding force in the corner portion and b is a straight side portion.

[Explanation of symbols]

1 die 2 Wrinkle hold 3 punches 4 cushion pins 5 Pressurizing cylinder 6 Cylinder part of hydraulic cam 7 Pump part of hydraulic cam 8 stroke end block 9 Pressurizing cylinder W Workpiece material

Claims (5)

[Claims] 1. In a press-molding die comprising a punch, a die and a wrinkle retainer, a pressure cylinder other than a cushion pin is used as a mechanism for generating a wrinkle retainer force.
c + D) <L ≦ 3 (dc + D), and install (cushion pin diameter: dc, pressurizing cylinder outer diameter:
D, distance between the center of the pressurizing cylinder and the closest cushion pin: L) The pressurizing cylinder and the wrinkle retainer come into contact with each other at an arbitrary stroke after the start of molding to start pressurization, so that the wrinkle retainer is pressed in one molding process. A press-molding die that can increase the force. 2. A press forming die comprising a punch, a die and a wrinkle retainer, wherein a cylinder, which is a pressure generating portion of a hydraulic cam, is installed between the die and the wrinkle retainer, and a pump of the hydraulic cam is provided outside the wrinkle retainer. Place it under the die,
A cylinder that pressurizes the hydraulic cam pump is installed at a position facing the hydraulic cam pump of the die, and when the pressurizing cylinder installed in the die contacts the pump at any stroke after the start of molding, the cylinder between the die and the wrinkle retainer A press-molding die that can reduce the wrinkle holding force in one molding process by starting pressing. 3. A press-molding die in which the mechanism according to claim 1 or 2 is incorporated into one die, and the wrinkle holding force can be increased and decreased in one molding step. 4. The wrinkle retainer is divided, and the mechanism according to any one of claims 1 to 3 is incorporated into all or a part of the divided portions, thereby making it possible to increase or decrease the wrinkle retainer force for each location. Press mold. 5. A press molding which uses the press die according to any one of claims 1 to 4 to increase or decrease the wrinkle holding force in one molding step and further increase or decrease the wrinkle holding force in each place. Method.