JPH0976020A - Method and device for bending - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a safe bender not rising the pressure under the condition sandwiching no work and also to prevent the elevation of the temperature. SOLUTION: One of either a lower table 5 provided with a lower die D or an upper table 9 provided with an upper die P is relatively moved to the other one by ram operating cylinders 13L and 13R to start bending under cooperation between the upper die P and the lower die D. When the pressure Pf of ram operating cylinders 13L and 13R become >= a given value α bending is performed by operating the crowning pressure to crowning cylinders 45C, 45L and 45R provided on the lower table 5. In addition to this method, the bender 1 for bending is also obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending method and apparatus for bending a work by cooperation of an upper die and a lower die.

[0002]

2. Description of the Related Art Conventionally, one of a lower table having a lower die and an upper table having an upper die is moved relative to the other by a ram operating cylinder to cooperate with the upper die and the lower die. The work is bent to bend the work. Moreover, so that the bent work does not have a boat shape,
In order to make the bending angle uniform in the bending width direction of the workpiece, the crowning cylinder provided on the lower table is operated, and the bending pressure is applied from the start of the bending operation to perform the bending operation.

[0003]

By the way, in the above-mentioned conventional technique, since the crowning pressure is applied to the lower table from the start of bending, the crowning pressure is applied to the work on the lower die before the upper die intervenes, The oil temperature will rise. In addition, the lower table is distorted more than necessary, which adversely affects the bending process.

If the crowning pressure is applied to the lower table after the bending work, the crowning may not be effective, and the crowning correction may not be sufficient.

It is an object of the present invention to provide a bending method and an apparatus therefor in which the pressure does not rise and the oil temperature is prevented from rising while the work is not clamped.

[0006]

In order to achieve the above object, the bending method of the present invention according to claim 1 is such that one of a lower table having a lower die and an upper table having an upper die is the other. When the pressure of the ram operating cylinder reaches a certain value or more by moving the ram operating cylinder relative to The crowning cylinder provided on the lower table is caused to exert a crowning pressure.

The bending method of the present invention according to claim 2 is the bending method according to claim 1, wherein when the pressure of the ram operating cylinder exceeds a certain value, the upper die is the upper die. It is characterized in that when the work in (1) is sandwiched, or a predetermined time has elapsed after the start of pressurization.

In the bending apparatus of the present invention according to claim 3, one of the lower table having the lower die and the upper table having the upper die is moved by the ram operating cylinder relative to the other. A bending device for bending a work in cooperation with the upper die and the lower die, a crowning cylinder provided on the lower table for applying a crowning pressure to the lower table, and a pressure for the ram operating cylinder. A pressure detector for detecting the pressure, a comparing means for determining whether or not the detected value of the pressure detector is a certain value or more, and a supply for supplying the crowning pressure to the crowning cylinder based on the output from the comparing means. Means and are provided.

In the bending method and apparatus of the present invention according to claims 1, 2 and 3, one of the lower table having the lower die and the upper table having the upper die is relatively positioned with respect to the other. The work is bent by the movement of the ram cylinder and the cooperation of the upper die and the lower die.

When bending work is started and the pressure of the ram working cylinder is set to a certain value or more, for example, the work having the upper die on the lower die is sandwiched, or after the start of pressurization for a predetermined time, When the comparison means detects that the detection value detected by the pressure detector has exceeded a certain value, crowning pressure is applied to the crowning cylinder provided on the lower table through the supply means.

When the work is not clamped, the crowning pressure is not applied to the lower table, so that the pressure is not increased and it is safe. Further, the oil temperature is prevented from rising.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, for example, a press brake 1 as a bending apparatus is provided with an upright side frame 3, and a lower table 5 is fixed to the lower front side of the side frame 3. It is provided. A die D as a lower die is provided on the lower table 5 via a die holder 7.

An upper table 9 which is vertically movable is provided on the front side of the upper portion of the side frame 3. A punch P as an upper die is provided below the upper table 9 via a plurality of intermediate plates 11. The side frame 3
The ram operating cylinder 13
L and 13R are provided, and the lower end of the piston rod 15 mounted on the ram operating cylinders 13L and 13R is fixed to the upper table 9.

With the above structure, the ram operating cylinders 13L, 13L with the work to be machined placed on the die D are placed.
When R is operated, the upper table 9 is moved up and down with respect to the lower table 5 via the piston rod 15, so that the punch P and the die D cooperate with each other to bend the work. .

An upper cylinder chamber 17 and a lower cylinder chamber 19 are provided in the ram operating cylinders 13L and 13R. Each of the upper cylinder chambers 17 has a pipe 2
One ends of the pipes 1 and 23 are connected, and the other end of the pipe 21 is connected in the middle of the pipe 23. The other end of the pipe 23 is connected to the A port of the 4-port 3-position switching valve 25.

One ends of pipes 27 and 29 are connected to the lower cylinder chamber 19, and the other end of the pipe 27 is connected to the middle of the pipe 29. The other end of the pipe 29 is connected to the B port of the 4-port 3-position switching valve 25. One ends of pipes 31 and 33 are connected to the P port and R port of the 4-port 3-position switching valve 25, respectively. The other ends of the pipes 31 and 33 communicate with the tank 35. A pump 37 is provided in the middle of the pipe 31,
A motor 39 is connected to the pump 37.

With the above structure, when the motor 39 is driven and the pump 37 is operated, the pressure oil in the tank 35 is discharged to the pipe 31. P of 4-port 3-position switching valve 25
When the port is connected to the A port and the T port is connected to the B port, the pressure oil in the pipe 31 is supplied to the upper cylinder chamber 17 of the ram working cylinders 13L and 13R via the pipes 23 and 21, so that the piston rod 15 The upper table 9 is lowered via the. At that time, the pressure oil in the lower cylinder chamber 19 flows into the pipe 33 through the pipes 27 and 29, and the tank 35
Is returned to.

P port and B of the 4-port 3-position switching valve 25
When the ports, T port and A port are made to communicate with each other, the pressure oil in the pipe 31 is supplied to the lower cylinder chamber 19 via the pipes 29 and 27, so that the upper table 9 is raised via the piston rod 15. . At that time, the upper cylinder chamber 1
The pressure oil of No. 7 flows through the pipes 21 and 23 to the pipe 33 and is returned to the tank 35.

Therefore, the ram operating cylinders 13L,
By moving the upper table 9 up and down by the operation of 13R, the punch P and the die D cooperate with each other to bend the workpiece placed on the die D.

A pipe 40 is provided in the middle of the pipes 23 and 29.
Pressure detectors 41A and 41B are provided via A and 40B. The pressure detector 41 detects the pressure of the pressure oil supplied to the upper cylinder chambers 17 of the ram working cylinders 13L and 13R. This pressure detector 41
A and 41B are connected to the control device 43. The applied pressure P _f is calculated by P _f = PG1 × A _H −PG2 × A _R (where PG1: cylinder head side pressure, PG2:
Cylinder rod side pressure, A _H : Cylinder head side area,
A _R cylinder rod side area).

Crowning cylinders 45C, 45 are provided at the lower part of the central portion and the left and right portions of the lower table 5.
L and 45R are provided. A lower cylinder chamber 47 is provided in each of the crowning cylinders 45C, 45L, 45R. One end of each of the pipes 49, 51, 53 is connected to each of the lower cylinder chambers 47, and
The other ends of the pipes 49, 51, 53 are connected in the middle of the pipe 55.

The other end of the pipe 55 is communicated with the tank 35, and a pump 57 and an electromagnetic valve 59 as a supply means are provided in the pipe 55 from the tank 35 side. Moreover, a motor 61 is connected to the pump 57.

With the above construction, when the motor 61 is driven and the pump 57 is operated, the pressure oil in the tank 35 is discharged into the pipe 55. The pressure oil discharged into the pipe 55 is supplied to the lower cylinder chamber 47 of the crowning cylinders 45C, 45L, 45R via the pipes 49, 51, 53 when the solenoid valve 59 is opened. As a result, the crowning cylinders 45C, 45L, 45R are activated to apply the crowning pressure to the lower table 5.

The solenoid valve 59 is connected to the control device 43. The control device 43 is provided with a memory 63 and a comparison means 65. The memory 63 has, for example, FIG.
In addition to the pressurization curve as shown in FIG. 1, the threshold value α is stored so that the crowning pressure is generated when the pressing force P _f becomes a constant value α or more. Further, in the comparison means 65, the actual pressure P _f detected by the pressure detector 41 and the constant value α stored in the memory 63.
Are compared with each other, and when P _f ≧ α, a command is issued from the control device 43 to open the solenoid valve 59.

The constant value α is preferably set when the punch P picks up a work on the die D, or after a lapse of a predetermined time after the start of pressurization.

Next, the operation from the start of bending work to the application of crowning pressure to the lower table 5 will be described with reference to FIG.
Describing based on the flowchart shown in FIG. 1, first, in step S1, the work is bent. That is,
With the work placed on the die D, the ram operating cylinders 13L and 13R are operated to lower the upper table 9.

While the upper table 9 is descending in step S2, the pressure of the pressure oil sent to the ram operating cylinders 13L, 13R is detected by the pressure detectors 41A, 41B, and the detected actual detection value P _f is detected. Is a comparison means 65 of the control device 43
Is taken into. In step S3, the constant value α stored in the memory 63 is fetched in the comparing means 65, so that the actual detection value P _f and the constant value α are compared.

When P _f <α, the process is returned to the step before step S2, and when P _f ≧ α, the process proceeds to step S4, and the control device 43 instructs the solenoid valve 59 to generate the crowning pressure. Is sent and the solenoid valve 59 is opened. By opening the solenoid valve 59 in step S5, the crowning cylinder 45 is transferred from the pipe 55 to the pipes 49, 51, 53.
The pressure oil is sent to the lower cylinder chambers 47 of C, 45L, 45R to operate the crowning cylinders 45C, 45L, 45R, and the crowning pressure is applied to the lower table 5.

Therefore, after the start of bending, the pressure P _{f of the} ram actuating cylinders 13L, 13R is not less than a certain value α (P _f ≧
α), crowning cylinders 45C, 4
Since the crowning pressure is applied to the 5L and 45R, it is possible to prevent the generation of unnecessary pressure. That is, the pressure is not increased in the state where the punch P does not pinch the work, the work is safe, and the rise of the oil temperature can be prevented.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes. In the example of this embodiment, the lower table 5 is fixed and the upper table 9 is fixed.
Although an example in which the upper table 9 is moved up and down is described, it is also possible to fix the upper table 9 and move the lower table 5 up and down.

[0032]

As can be understood from the examples of the embodiment as described above, according to the inventions of claims 1, 2 and 3, after the start of bending, the pressure of the ram operating cylinder becomes a certain value or more. At this time, since the crowning pressure is made to act on the crowning cylinder, it is possible to prevent generation of unnecessary pressure. That is, it is safe because the pressure does not rise in the state where the upper die does not clamp the work, and it is possible to prevent the oil temperature from rising.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a bending apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a pressing force applied to a ram operating cylinder stored in a memory of a control device and time.

FIG. 3 is a flowchart of an operation of applying crowning pressure to a lower table.

[Explanation of symbols]

 1 Press Brake (Bending Machine) 5 Lower Table 9 Upper Table 13L, 13R Ram Operating Cylinder 41 Pressure Detector 43 Control Device 45C, 45L, 45R Crowning Cylinder 59 Solenoid Valve (Supply Means) 63 Memory 65 Comparison Means P Punch (Upper mold) D die (Lower mold)

Claims (3)

[Claims] 1. Cooperation between the upper die and the lower die by moving one of a lower table having a lower die and an upper table having an upper die by a ram operating cylinder relative to the other. Bending of the work is started, and the crowning pressure is applied to the crowning cylinder provided on the lower table when the pressure of the ram operating cylinder reaches a certain value or more. Method. 2. When the pressure of the ram operating cylinder exceeds a certain value, it means that the upper die is sandwiching a work on the lower die or after a predetermined time has elapsed after the start of pressurization. The bending method according to claim 1, wherein: 3. Cooperation between the upper die and the lower die by moving one of a lower table having the lower die and an upper table having the upper die by a ram operating cylinder relative to the other. With a bending device that bends the work with
A crowning cylinder provided on the lower table for applying a crowning pressure to the lower table, a pressure detector for detecting the pressure of the ram operating cylinder, and whether or not a detection value of the pressure detector is a certain value or more is determined. Comparing means for supplying the crowning pressure to the crowning cylinder based on the output from the comparing means,
A bending apparatus comprising: