JP3720216B2 - Press mold forming aid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
Some press-molding steel sheets are used in combination with a cushion mechanism that partially sandwiches the blank against the blank holder. And the function which shape | molds the specific location of a blank is provided to this cushion mechanism. The present invention belongs to the technical field of such a cushion mechanism.
[0002]
[Prior art]
In press forming of steel plates, etc., the periphery of the steel plate is first pressed with a blank holder, and then the press die is advanced to form. In addition, as a supplement to this blank holder, a blank is provided with a separately provided cushion mechanism. Is being done. And the specific location, for example, a difficult-to-form part, is also molded using this cushion mechanism. This cushion mechanism also has a function to push up the molded product, and the push-up time is generally the time when the press die is retracted and the blank holder is opened, so that the workpiece is not restrained. Is. By selecting such a time, even if the cushion mechanism comes into contact with the workpiece, the workpiece moves easily, so that the workpiece is not damaged or deformed. In this cushion mechanism, a control mechanism is generally provided in a bolster of a press machine, and the operation timing is selected as described above.
[0003]
[Problems to be solved by the invention]
In the system as described above, the drive mechanism portion that is a part of the entire cushion mechanism is incorporated in the bolster, and the members that act on the other blanks are incorporated in the press die. Therefore, the drive mechanism and the member acting on the blank must be connected in some form. Therefore, when replacing the press die, the above mechanism must be connected each time, which is disadvantageous in terms of labor and time for replacement.
[0004]
[Means for solving the problems and their functions]
The present invention has been devised to solve the above-described problems, finds a method unrelated to the bolster, and causes the driving means employed therein, that is, the cushion mechanism unit to perform a special behavior. That is the basic idea. The invention of claim 1, cushion mechanism attaching the blank partially sandwiched press die having a blank holder is used in combination, in which the molding auxiliary member of the cushion mechanism is configured to perform shaping of the specific portion of the blank The driving means for the forming auxiliary member is incorporated in the press die, and the driving means retracts the forming auxiliary member to a predetermined position in conjunction with the movement of the press die during the forming process of the workpiece, and the press die moves backward after forming. At the same time, the blank holder is provided with a function of maintaining the retracted position until the workpiece is released. At least a cylinder fixed to the press die, a piston sliding in the cylinder, and the molding auxiliary member are provided. A spring means that pushes out the forming auxiliary member is installed on one side of the piston. A means for restraining the elasticity of the spring means is installed on the other side of the ton, and the means for restraining the elasticity of the spring means is an oil for supplying hydraulic oil to an oil chamber provided on the other side of the piston. A check valve arranged in a direction allowing oil flow to the oil chamber in the path, and through the check valve as the molding auxiliary member moves back to a predetermined position in conjunction with the movement of the press die. The hydraulic oil is sucked into the oil chamber.
Therefore, when the forming auxiliary member has to be retracted, the retracting is allowed and retracted to a predetermined position by the elastic reduction of the spring means. Simultaneously with this retraction, the restraining function on the other side of the piston prohibits displacement by the spring means, that is, the movement of the forming auxiliary member to return to the advance direction, so that the predetermined retraction position of the forming auxiliary member is linked to the movement of the press die. And is reliably maintained.
[0005]
The invention of claim 2 is characterized in that, in claim 1, the spring means is an enclosed gas.
Therefore, when the spring function is obtained by the compressibility of the gas and the forming auxiliary member is retracted, the reaction force when the forming auxiliary member is retracted is set to an appropriate value by appropriately selecting the pressure value of the gas. Can be easily done.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail according to the illustrated embodiment. An upper bolster 1 and a lower bolster 2 that form a part of the press machine are arranged so as to face each other vertically, and the lower side 2 is in a stationary state and the upper side is stroked up and down. The press mold is composed of an upper mold 3 and a lower mold 4, which are firmly coupled to the upper bolster 1 and the lower bolster 2, respectively. The forming auxiliary member 5 is controlled to advance and retreat by the driving means 6 and also functions as an auxiliary press die in the press die. The driving means 6 is provided with a function of retracting the forming auxiliary member to a predetermined position at the time of forming the workpiece, and maintaining the retracted position until the press die moves backward after the forming and the blank holder opens the workpiece. .
[0009]
The driving means 6 is incorporated in the upper die 3 and comprises at least a cylinder 7 fixed to the press die (upper die 3), a piston 8 that slides in the cylinder, and a piston rod 9 that pushes out the molding auxiliary member 5. On one side of the piston 8, a spring means 10 for pushing out the molding auxiliary member is installed, and on the other side of the piston, a means 11 for restraining the elasticity of the spring means 10 is installed. As a method for realizing the spring means 10, various methods such as a compression coil spring and an enclosed gas can be applied. Here, nitrogen gas is enclosed on one side of the piston 8. Due to this gas pressure, a force in the extrusion direction is applied to the forming auxiliary member 5. On the other hand, the restraining means 11 can be a mechanical mechanism such as a collet chuck, and can adopt a system that allows the piston rod 9 to move backward but prohibits advancing, or a system that uses an incompressible fluid. However, here is the latter type. Reference numeral 11 denotes a means for restraining, and also indicates hydraulic oil for the hydraulic equipment. The hydraulic oil 11 is sucked when the piston 8 moves backward, and is pushed out when the hydraulic oil advances by gas pressure. This fluid control will be described later with reference to FIG.
[0010]
When the part such as the door frame 12 shown in FIG. 5 is formed, the pillar portion 13 has a relatively simple shape, so that there is no problem in forming, but the intersection 15 between the roof rail 14 and the pillar portion 13 is localized. In order to achieve deep drawing, an auxiliary press die, that is, a molding auxiliary member is employed. This is a member denoted by reference numeral 5, and is connected to the piston rod 9 via a connecting shaft 16.
[0011]
The upper die 3 is provided with a receiving hole 17, in which the cylinder 7 is received and fixed firmly with fixing bolts 18, 18, and a through hole 19 is opened continuously to the receiving hole 17, The piston rod 9 faces the auxiliary press mold, that is, the molding auxiliary member 5 can be advanced and retracted.
[0012]
Reference numeral 20 denotes a blank holder, which includes a lower surface 21 formed around the upper die 3 and a holding die 22 arranged around the lower die 4, and the holding die 22 is a cushion pin 23 or a hydraulic cylinder 25. It is supported by a cushioning device made up of and the like. In addition, a stationary die 24 that is paired with the auxiliary press die 5 is disposed on the lower die 4.
[0013]
The assembly of the stationary die 24, the molding auxiliary member 5, the connecting shaft 16, the piston rod 9, the piston 8, the cylinder 7, and the fluid in the cylinder 7 described above forms a “cushion mechanism”.
[0014]
FIG. 4 is a control circuit diagram of the hydraulic oil. Nitrogen gas is sealed on the upper side of the piston 8, and the hydraulic oil is contained in the oil chamber 26 on the lower side of the piston 8. The oil chamber 26 is connected to an oil tank 29 via a check valve 27 and a pilot valve 28, and compressed air from the air pipe 30 acts on the oil surface of the oil tank 29, so that supply pressure is applied to the hydraulic oil. Yes. The check valve 27 is disposed in a direction that allows oil flow to the oil chamber 26. The pilot valve 28 is switched by introducing control air for automatic operation of the press machine through the air pipe 31. When the air is supplied to the pilot valve 28, the hydraulic oil in the oil chamber 26 returns to the oil tank 29. Therefore, the piston rod 9 (molding auxiliary member 5) is advanced by the pressure of nitrogen gas. . When the supply of air is stopped, the hydraulic oil in the oil chamber 26 is not discharged anywhere, and the piston rod 9 (molding auxiliary member 5) is relatively retracted when the upper die 3 is advanced. At this time, the hydraulic oil is only sucked into the oil chamber 26 and is enclosed in the oil chamber 26, so that the advancement of the piston 8 (advancement of the molding auxiliary member 5) by the gas pressure is prohibited.
[0015]
The operation of this embodiment will be described below. FIG. 1 shows a state in which a blank 32 is placed between the upper and lower molds 3, 4. The piston 8 is at a position where it is lowered most by the gas pressure, and the molding auxiliary member 5 protrudes slightly. When the upper mold 3 is lowered, the periphery of the blank 32 is first sandwiched by the blank holder 20, and when the upper mold 3 is further lowered, the blank 32 is molded by the molding auxiliary member 5 and the stationary mold 24. Beginning, deep drawing and molding of large bends are started in advance. Next, the other parts are molded to the state shown in FIG. As apparent from FIG. 2, the molding auxiliary member 5 moves backward relatively, whereby the nitrogen gas 10 is compressed and the hydraulic oil is sucked into the oil chamber 26. Thus, the reaction force when the molding auxiliary member 5 is pushed in is set by the pressure of the nitrogen gas and the flow path resistance value of the check valve 27. By optimizing this value, the molding by the molding auxiliary member 5 is soundly performed.
[0016]
When the upper mold 3 is returned from the state shown in FIG. 2, the hydraulic oil in the oil chamber 26 remains sealed, so the relative position between the molding auxiliary member 5 and the upper mold 3 remains unchanged. In the figure, which is in a state, since the clamping function of the blank holder 20 is maintained, the workpiece is not unconstrained. Here, when the upper die 3 is further retracted, the clamping of the blank holder 20 is released, and the workpiece is not restrained. Then, when the pilot valve 28 is switched by air supply so that the hydraulic oil in the oil chamber 26 can flow out to the oil tank 29, the molding auxiliary member 5 is pushed out by the pressure of the nitrogen gas, and the workpiece is separated from the upper mold 3. Mold. Since the above-described switching of the pilot valve 28 uses air for automatic operation of the press machine, the working air can be supplied to the pilot valve 28 at the stroke time when the blank holder 20 opens the workpiece.
[0017]
Although not described in the claims, the following matters can be described in the claims. That is, by selecting the flow passage area and gas pressure when the hydraulic oil is sucked into the oil chamber 26, the backward reaction force of the forming auxiliary member 5 according to the degree of deformation of the portion formed by the auxiliary press die 5 can be increased. It can be set to avoid the occurrence of scratches or cracks in the molded part.
On the other hand, by selecting the flow passage area when hydraulic oil flows out from the oil chamber 26, the advance output at the time of workpiece release can be optimized, so that the workpiece is not damaged. In addition, this invention also includes installing the drive means 6 in any one of the upper mold | type 3 and the lower mold | type 4, or both upper and lower sides. Furthermore, the press machine to which the present invention is applied may be either a single action system or a double action system.
[0018]
【The invention's effect】
According to the present invention, after the press molding, the press die moves backward, and the blank holder is opened, and then the molding auxiliary member pushes out the workpiece, and the driving means of the molding auxiliary member is incorporated in the press die. Therefore, all necessary functions can be satisfied inside the press die without having any mechanical relationship with the bolster. Therefore, when exchanging the press die, the exchanging work is greatly simplified without any relation to the mechanism on the bolster side.
[0019]
The above-mentioned driving means has a function of retreating the forming auxiliary member to a predetermined position at the time of forming the workpiece, and maintaining the retracted position until the press die is retreated and the blank holder opens the work after forming. Therefore, when the forming auxiliary member advances, the restraining action on the work has already disappeared, and when the forming auxiliary member hits the work, the work is immediately pushed out. Therefore, since the forming auxiliary member does not push the work strongly, the work is not damaged or deformed. This is very advantageous particularly when the appearance quality is regarded as important, such as an automobile outer plate.
[0020]
Further, a specific configuration of the driving means includes at least a cylinder fixed to a press mold, a piston that slides in the cylinder, and a piston rod that pushes the molding auxiliary member, and pushes the molding auxiliary member to one side of the piston. A spring means is installed, and a means for restraining the elasticity of the spring means is installed on the other side of the piston. The means for restraining the elasticity of the spring means operates on an oil chamber provided on the other side of the piston. A check valve disposed in a direction allowing oil flow to the oil chamber in an oil passage for supplying oil, and the molding auxiliary member is moved back to a predetermined position in conjunction with the movement of the press die. since the hydraulic oil through the check valve is intended to be sucked into the oil chamber, when the molding auxiliary member must retracted by elastic contraction of the spring means, the retraction Acceptable retracted to a predetermined position. Simultaneously with this retraction, the restraining function on the other side of the piston prohibits displacement by the spring means, that is, the movement of the forming auxiliary member to return to the advance direction, so that the predetermined retraction position of the forming auxiliary member is linked to the movement of the press die. And is reliably maintained.
[0021]
Since the above-mentioned spring means is a sealed gas, a spring function is obtained by the compressibility of the gas, and when the molding auxiliary member is retracted, by appropriately selecting the pressure value of the gas, It is easy to set the reaction force at the time of reverse to an appropriate value.
[0022]
Since the tip of the forming auxiliary member is an auxiliary press mold that forms a part of the workpiece, the reaction force required for the auxiliary press mold during retraction and the extrusion force during forming assist must be selected to an appropriate value. Can do. In particular, it is important that the reaction force control at the time of retraction is appropriately selected according to the degree of deformation of the steel sheet, for example, the degree of deep drawing. If this selection is not appropriate, the molding local part may be scratched or cracked, so that delicate control is required, and the present invention is also very advantageous in this respect. is there.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing an embodiment of the present invention, in which an upper mold is in a most raised state.
FIG. 2 is a longitudinal sectional side view showing a completed state of FIG. 1;
FIG. 3 is a partial vertical side view showing a transient state when the upper mold is retracted.
FIG. 4 is a circuit diagram of hydraulic oil.
FIG. 5 is a three-dimensional view of an automobile door frame.
[Explanation of symbols]
3, 4 Press mold 3 Upper mold 4 Lower mold 20 Blank holder 5 Molding auxiliary member 6 Drive means 7 Cylinder 8 Piston 9 Piston rod 10 Spring means 11 Constraint means 10 Gas 11 Liquid

Claims (2)

Cushion mechanism sandwiching the blank to the press-type partially having a blank holder is used in combination, in which the molding auxiliary member of the cushion mechanism is configured to perform shaping of the specific portion of the blank, driving of the auxiliary molding member The means is incorporated in the press die, and the driving means retracts the molding auxiliary member to a predetermined position in conjunction with the movement of the press die at the time of molding the workpiece, and after the molding, the press die moves backward and the blank holder holds the workpiece. A function of maintaining the retracted position until it is opened is provided, comprising at least a cylinder fixed to the press mold, a piston sliding in the cylinder, and a piston rod coupled to the molding auxiliary member. The spring means for pushing out the molding auxiliary member is installed on one side of the piston, and the other side of the piston Means for restraining the elasticity of the spring means is installed, and means for restraining the elasticity of the spring means is provided to the oil chamber in an oil passage for supplying hydraulic oil to an oil chamber provided on the other side of the piston. The check valve is arranged in a direction that allows oil flow of the oil, and hydraulic oil is introduced into the oil chamber via the check valve as the molding auxiliary member moves back to a predetermined position in conjunction with the movement of the press die. A press-type molding auxiliary device characterized by being inhaled . 2. The press-type molding auxiliary device according to claim 1, wherein the spring means is an enclosed gas .

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