JP3238524B2 - Bending machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending machine provided with a plate thickness detecting function.

[0002]

2. Description of the Related Art Conventionally, for example, in a press brake as a bending machine, a target value operation is known irrespective of the thickness of a work. In this target value operation, for example, the work is placed and fixed on a die provided on the lower table, and the upper table equipped with the punch is lowered at a high speed so that the tip of the punch comes into contact with the work at a low speed. The bending is performed by switching.

[0003] However, even when the same work or the same shape of a work is bent, if the lot of the work is changed, for example, even if the thickness is the same 1.6 mm, the tendency of the thickness variation is changed. There is. In addition, even in the same work, the thickness may vary at the left end, the center, and the right end. For this reason, there has been a problem that an accurate bending angle cannot be obtained in the target value operation described above.

[0004] Therefore, in order to obtain an accurate bending angle even if the thickness of the workpiece varies, a bending machine having a thickness detecting function has been developed and used. In the thickness detection operation by the bending machine equipped with this thickness detection function, the upper table is moved down at high speed, switched to low speed halfway until it comes into contact with the work, and lowered. In addition to detecting the thickness, the work is bent based on the detected thickness.

[0005]

By the way, the work W as shown in FIG. 6 can be bent at the A and B places by the thickness detection operation, but at the C place, the thickness can be detected. Bending cannot be performed during operation. As described above, if there is at least one part (that is, a process) where the bending process cannot be performed in the plate thickness detection operation, the entire processing program of the work W must be bent by the target value operation processing program. That is, the thickness detection operation data can be used only for the thickness detection operation, and the target value operation data can be used only for the target value operation, and the bending operation in which the data is mixed cannot be bent by the thickness detection operation. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems by performing a work of detecting a thickness when a work requiring a thickness detection operation and a process not requiring the operation are mixed when bending a workpiece. It is an object of the present invention to provide a bending machine in which a thickness detection operation is performed as it is in a simple process, and a target value operation can be performed in a process where the thickness detection operation is not necessary, so that the working efficiency can be slightly improved.

[0007]

Means for Solving the Problems Conventional problems as described above
In view of the above, the present invention provides a method for bending a workpiece.
Lower table with die and upper table with punch
The die and the punch perform an approaching / separating operation between the die and the punch.
And a driving device for controlling the operation of the driving device.
Providing an NC device for controlling, and
Detects that the punch has contacted the workpiece and
Bending machine with sheet thickness detection function to detect sheet thickness
In the NC device, the punch may be attached to the workpiece.
Switch to the thickness detection speed halfway until contact
When the punch touches the work, it switches to the bending speed.
Thickness inspection that stores a program for performing bending in advance
The operation program memory and the punch
When approaching the workpiece at high speed and contacting the workpiece, the bending speed
A program for switching and performing bending is stored in advance.
The operation program memory and the work
Process data file containing bending process data
Display means; and the step data displayed on the display means.
The process data in the data file
Use the operation program of the operation program memory
Or the operation of the operation program memory according to the target value
A selection means for inputting whether to use the program;
It is a configuration provided with.

[0008]

[0009]

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

First, a bending machine provided with a sheet thickness detecting function will be described. Referring to FIG. 5, in the bending machine 1, a lower table 5 as a fixed table having a die 3 mounted on an upper end surface is fixed to a frame. An upper table 9 as a ram in which a punch 7 facing the die 3 is mounted on a lower end surface is provided to be vertically movable.

On the left and right of the upper table 9, ball screws 11 are provided.
The upper end of the ball screw 11 is screwed, and a pulley 13 is attached to each of the ball screws 11 below. Pulley 13
Is a timing belt 1 to an AC servomotor 17 as a driving device controlled by an NC device 15 as a control unit.
9, the upper table 9 is moved up and down by the AC servomotor 17 driving the ball screw 11 to rotate. In addition,
The AC servomotor 17 is provided with an encoder 17E.

Therefore, the AC servomotor 17 drives the ball screw 11 to rotate and lowers the upper table 9, thereby lowering the punch 7 and bringing it closer to and engaging with the die 3. The bent work W is subjected to bending.

The upper table 9 has left and right linear scales 33 as external position detecting means for detecting the vertical position of the upper table 9 from outside.

On the other hand, the outline of the control contents of the NC unit 15 will be described with reference to FIG. The NC device 15 is a main control unit 25
And a deviation counter 27 connected to the main controller 25.
And a loop gain calculator 29 connected to the deviation counter 27, a speed controller 31 connected to the loop gain calculator 29, and the like.
The rotation of the AC servomotor 17 is controlled via the.

The AC servomotor 17 is provided with a speed detector 33 such as a tachometer, for example, and detects the speed of the upper table 9 and feeds it back to the speed controller 31. Thereby, the AC servomotor 17
In this case, the speed commanded by the speed control unit 31 is accurately implemented.

The position of the upper table 9 moved up and down by the AC servomotor 17 is measured by the aforementioned linear scale 23 provided independently of the upper table 9. The position of the upper table 9 detected by the linear scale 23 is fed back to the deviation counter 27 as a position feedback pulse RP.

The main control section 25 stores the shape and dimensions of the punch 7 and the die 3 and processing data and the like, and performs NC control of the bending processing.

The deviation counter 27 is configured to control the command position (feed pulse) sent from the main control unit 25 and the linear scale 2.
The position error amount is detected by counting error pulses from the position feedback pulse RP sent from No.3. Therefore, this position deviation amount is obtained as a digital amount. Further, the deviation counter 27 has a loop gain calculator 29.
Is connected, and the position deviation amount in the normal state is obtained based on the following equation (1).

In the servo mechanism of the so-called full closed loop system configured as described above, control is performed as follows.

First, normal movement is performed with a fixed deviation given by the following equation between the command position from the main control unit 25 and the detection position of the upper table 9 by the linear scale 23.

Positional deviation amount = feed speed (mm) / 60 / loop gain (1 / sec) (1) Here, the loop gain represents the characteristic of the servo mechanism, and the higher the value of the loop gain, the higher the value of the loop gain. It indicates that the adaptability is good.

When the punch 7 comes into contact with the work W, the lowering of the upper table 9 is hindered by the resistance of the work W, and the rotation of the motor is absorbed by the play of the machine such as a backlash. Therefore, the deviation between the position command from the main control unit 25 and the detected position of the upper table 9 detected by the linear scale 23 increases. That is, the deviation amount counted by the deviation counter 27 from the feed pulse from the main control unit 25 and the position feedback pulse RP from the linear scale 23 increases.

On the other hand, the "deviation" during the constant speed movement is the above-mentioned 1
Since it is theoretically obtained by the equation, when the deviation amount is exceeded, it is detected as a pinching point (contact point), that is, a position where the punch 7 comes into contact with the work W and the lowering of the upper table 9 is temporarily stopped. be able to.

The main control unit 25 estimates the thickness of the punch 7 and the die 3 based on the information on the shape of the punch 7 and the die 3 stored on the basis of the pinching point obtained as described above, and stores the upper table 9 in the bending process. Is corrected, and control is performed so that a desired bending angle is obtained.

FIG. 4 shows changes over time such as the torque value and speed of the AC servomotor 17 and the position of the upper table 9. In the figure, there is a slight time difference between the point PT at which the torque changes and the point PV at which the speed changes. This is because the speed change has a delay in the software processing as compared with the torque change. In the thickness measurement according to this embodiment, since the position deviation amount higher than the speed is used, more accurate detection can be performed than when the thickness is detected based on the change in speed. .

In FIG. 4, the portion where the speed rises indicates that the position deviation amount has increased from the above-mentioned equation (1).

As described above, the detected "position deviation amount" is a digital amount obtained by counting error pulses. Since the thickness is detected based on this digital amount, the torque of the AC servomotor 17 is reduced as in the prior art. An accurate value can be obtained as compared with a method of detecting a change.

Also, in the detection method using torque,
The processing of the small workpiece W is difficult to detect because the bending pressure is small and the torque change is very small. However, the bending machine in this embodiment can detect accurately.

Further, in the servo loop, since the delay in the soft processing time of the feedback system is small, the pinching point can be detected in real time as compared with the method using torque and speed.

In the case where the bending machine 1 having the above-described plate thickness detecting function performs bending at the A, B, and C locations of the work W as shown in FIG. The plate thickness detection operation can be performed at the C point to perform the target value operation.

That is, the NC device 15 has a CPU 3
The CPU 35 is connected to input means 37 such as a keyboard for inputting the width and length of the work W, and display means 39 such as a CRT for displaying data and the like. Also, an execution / non-execution selection means 41 for determining whether or not to perform the thickness detection step is connected.

As shown in FIG. 2, the CPU 35 is connected to a process data file 43 in which data for each process is stored. Operation program memories 45 and 47 indicating operations are connected. In the operation program memory 45 based on the sheet thickness detection, the upper table 9 descends at a high speed in advance, and is switched to a sheet thickness detection speed (low speed) halfway before coming into contact with the work W, and descends.
, A program for switching to a bending speed (low speed) and performing a bending process is stored. Further, in the operation program memory 47 based on the target value, a program for switching the bending speed (low speed) to perform the bending process when the upper table 9 descends at a high speed and comes into contact with the workpiece W is stored in advance.

The CPU 35 is connected to a program memory 49 in which a processing program for performing bending on the work W is stored.

With the above configuration, the process data file 4
3 is displayed on the display means 39, for example, on a CRT, as shown in FIG. In the process data displayed on this CRT, whether the thickness is to be detected or
Since there is a sheet thickness detection item, the operator inputs "1" by using, for example, a keyboard of the selection means 41 when the operator detects the sheet thickness, and inputs "0" when the operator does not detect the sheet thickness.
Enter Therefore, 1, 0, 1,... Are inputted and stored for each process.

When the thickness detection is "1", the operation program stored in the operation program memory 45 by the thickness detection is "0". When the thickness detection is "0", the operation program based on the target value is used. Operation programs stored in the memory 47 are machining programs and memories 49, respectively.
And a machining program for each actual process is created. By executing this machining program,
For example, it is possible to easily perform the bending process by skillfully combining the operation at the A, B, and C locations shown in FIG. Can be improved.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes. In the above-described embodiment, the case where the upper table 9 is lowered to perform the bending is described. However, the present invention is not limited thereto, and the same applies to the case where the lower table 5 is raised to perform the bending.

[0037]

As is apparent from the above description of the embodiment, in the present invention, the NC device 15 is used for detecting the plate thickness.
Operation program memory 45 and operation program
Program memory 47 and process data
・ Bending of work W stored in file 43
In the state where the process data is displayed on the display means 39,
Operation program based on sheet thickness detection Stored in memory 45
Use the operation program that is
Operation stored in program memory 47
Enter in the process data whether to use a program
For the work W
When performing the cutting process, the operation
According to the operation program stored in the RAM memory 45,
The operation program memory 4 based on the target value
Fold the operation according to the operation program stored in 7
It can be set in advance for each grinding process.
Therefore, processes that require the thickness detection operation and processes that do not require
Easy to bend even in the bending process where the process is mixed
Which can be used for grinding
Can solve the problem.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment embodying the present invention.

FIG. 2 is an example of process data stored in a process data file in FIG. 1;

FIG. 3 is a block diagram showing an example of a sheet thickness measurement in the bending machine according to the present invention.

FIG. 4 is a relationship diagram showing a temporal change of a ram position, a torque and a speed of an AC servomotor.

FIG. 5 is a perspective view showing an embodiment of a bending machine according to the present invention.

FIG. 6 is an explanatory diagram of an example in which a work is bent.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bending machine 3 Die 5 Lower table (fixed table) 7 Punch 9 Upper table (ram) 15 NC device (control part) 17 AC servomotor (drive means) 23 Linear scale (external position detection means) 41 Selection means 43 Process data file 45 Operation program memory based on sheet thickness detection 47 Operation program memory based on target value detection 49 Processing program memory

Claims (1)

(57) [Claims] 1. A method for bending a workpiece (W).
Lower table (5) with die (3) and punch
An upper table (9) provided with (7);
A drive for performing the approaching / separating operation between (3) and the punch (7).
And a driving device (17).
An NC device (15) for controlling the operation;
The work (W) on the die (3) is punched with the punch (7).
Is detected and the thickness of the work (W) is detected.
In a bending machine with a thickness detection function
In the NC device (15), the punch (7) may
Switch to sheet thickness detection speed before contacting (W)
At the same time, the punch (7) comes into contact with the work (W).
Program for performing bending processing by switching to different bending speeds
Program memory by detecting the thickness of a sheet in which
(45) and the punch (7) is high on the work (W).
Switch to bending speed when approaching the workpiece (W) quickly
The program that stores the program for performing the bending process in advance
Work program memory (47) by standard value and work
Process data filed from the bending process data of (W)
File (43), display means (39), the display means
The process data file (4) displayed in the column (39)
Operation process by the above thickness detection for the process data of 3)
Whether to use the operation program of the gram memory (45)
Or an operation program memory based on the target value (47)
To select whether to use the operation program
And a step (41) .