JPH05138254A - Method and equipment for measuring plate thickness in bender - Google Patents

Abstract

PURPOSE:To provide a plate thickness measuring equipment for a bender which can measure a work automatically with a high accuracy even when it is small in size or thin in plate thickness. CONSTITUTION:A positional deviation between the position of an upper table 9 detected by an inner position detecting means 22 provided in an AC servo motor(driving means) 17 to vertically move an outer table(ram) 9 and the position of the upper table 9 and the position of the upper table 9 detected by a linear scale (outer position detecting means) 21 provided at the outer part of the upper table 9 is found. The speed of the upper table is found in accordance with the positional deviation found in this way and the thickness of the work is measured based on the point of change of the upper table speed. Accordingly, since the point of reference is decided more clearly than when the point of change of the torque of the AC servo motor 17 is used as a reference as in the past method of measurement, the plate thickness can be measured with a high accuracy even when it is thin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness measuring method and measuring device in a bender, and more particularly to a thickness measuring method and measuring device in a bender controlled by a full closed loop system.

[0002]

2. Description of the Related Art Conventionally, the most rudimentary plate thickness measuring method is to directly measure the plate thickness using a measuring instrument such as a caliper. However, since it is necessary to measure each time the work is bent, it takes time, which hinders automation of machining work.

Therefore, a so-called semi-closed loop for automatically detecting the position of the punch die by detecting the position of the punch die from the rotary shaft of the servomotor or by detecting the rotation angle of the ball screw for moving the ram up and down. By adopting the method, it is no longer necessary to measure the thickness of the work piece by piece.

However, in this measuring method, the positional accuracy of the machine varies depending on the accuracy of the ball screw, and since the position is detected before the ram which is the final control target, the accuracy is poor. is there.

Therefore, a method of measuring the plate thickness by utilizing the deviation of the position when the punch die mounted on the ram of the bender comes into contact with the work (so-called full closed loop method)
Is proposed. That is, using the deviation between the detection position of the punch die by the encoder installed in the servo motor that moves the ram up and down and the detection position by the linear scale that is installed on the ram and directly measures the vertical movement of the ram, the workpiece plate is used. Since it is a method of automatically measuring the thickness, highly accurate measurement is possible.

[0006]

However, in such a conventional technique, when the pressure when the punch die comes into contact with the work is small (in the case of a small work or a thin work), the time of the contact occurs. Since it was not clear and it was difficult to judge the detection position, it was not always possible to measure with high accuracy.

The object of the present invention has been made in view of such a conventional technique, and it is possible to automatically and accurately measure a plate of a bender even if the work is small or the plate is thin. A thickness measuring device is provided.

[0008]

In order to achieve the above-mentioned object, the plate thickness measuring method in the bender according to the present invention moves the ram up and down by controlling the drive means by the command pulse from the control section. By using the thickness measurement method in a bender that performs bending, the positional deviation between the ram position detected by the internal position detection means provided in the drive means and the ram position detected by the external position detection means provided outside the ram is determined. It is characterized in that the ram speed is obtained based on the obtained position deviation and the plate thickness of the work is measured with reference to the point where the ram speed changes.

The measuring device is provided with a ram provided with a punch die or a die die so as to be vertically movable, and a die die or a die die opposed to the punch die or the die die. A bender equipped with a mounted fixed table, a driving means for moving the ram up and down, and a control section for controlling the driving means, which is equipped with an internal position detection means for detecting the position of the ram. An external position detecting means for detecting the ram position from the outside is provided, and a ram speed is calculated by comparing the ram position detected by the internal position detecting means with the ram position detected by the external position detecting means. A part is provided in the control part.

[0010]

According to the plate thickness measuring method and the measuring device in the bender according to the present invention, the ram position detected by the internal position detecting means provided in the driving means for vertically moving the ram and the external position provided outside the ram. A position deviation from the ram position detected by the detecting means is obtained. Then, the computing unit obtains the ram speed based on the obtained position deviation, and the plate thickness of the work is measured based on the point where the ram speed changes. Therefore, as in the case of the conventional measurement method, the reference point is clearly determined as compared with the case where the change point of the torque of the driving means is used as the reference, so that the plate thickness can be measured with high accuracy even when the plate thickness is thin. it can.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

5 and 6 show the entire structure of the vendor 1. In this bender 1, the die mold 3 is attached to the upper end surface.
The lower table 5 mounted with is fixed to the frame. An upper table 9 having a punch die 7 facing the die die 3 mounted on the lower end surface is provided so as to be movable up and down. The work W placed between the dies 3 and 7 is bent.

An upper end portion of a ball screw 11 is screwed onto the upper table 9, and a pulley 13 is attached to the ball screw 11 below. The pulley 13 is connected to an AC servomotor 17 controlled by an NC device 15 as a control unit via a timing belt 19 and a pulley 20.
The upper table 9 moves up and down by rotationally driving.

The upper table 9 is provided with linear scales 21 on the left and right as external position detecting means for detecting the vertical position of the upper table 9 from the outside. The AC servomotor 17 is provided with an internal position detecting means 22 such as an encoder for detecting the position of the upper table 9 from the rotation of the AC servomotor 17.

On the other hand, the outline of the control contents of the NC device 15 will be described with reference to FIG. The NC device 15 has a main controller 23.
And a position control unit 25 including a calculation unit, a speed control unit 27, and the like. The rotation of the AC servomotor 17 is controlled via the speed control unit 27. AC servo motor 1
7 includes a speed detector 29 such as a tacho generator.
Is provided, and the speed of the upper table 9 is detected and fed back to the speed control unit 27. The position of the upper table 9 which moves up and down by the AC servomotor 17 is measured by the above-mentioned linear scale 21 provided independently of the upper table 9. The position of the upper table 9 detected by the linear scale 21 is fed back to the position controller 25 as a position feedback pulse RP.

In the so-called full-closed-loop type servomechanism constructed in this way, control is performed as follows. The main controller 23 issues a position command for the upper table 9 to the position controller 25, and the position controller 25 sends the speed command for the upper table 9 based on the commanded position.
Depart to 7. Then, the speed control unit 27 controls the rotation speed and the like of the AC servomotor 17 according to the speed command. On the other hand, the position of the upper table 9 detected by the linear scale 21 is used as the position feedback pulse RP in the position controller 25.
The position deviation amount is obtained by calculating the difference between the position detected by the linear scale 21 and the command issued from the main control unit 23 to the position control unit 25. The position control unit 25 calculates the speed by the following formula based on this position deviation amount, and the speed = position deviation amount × 60 × loop gain ... 1 The speed command is issued to the speed control unit 27 to output the AC servo motor 1
The rotation speed of 7 is controlled.

Here, the loop gain represents the characteristic of the servo mechanism, and the higher the loop gain value, the better the adaptability.

With reference to FIG. 2 as well, changes in the position and speed of the upper table 9 due to the aforementioned control will be described. Here, the solid line in the figure indicates the work W having a thick plate,
The broken line shows the case where the work W having a small plate thickness is bent. Since the upper table 9 descends from the top dead center P0 at a constant speed, there is no change in speed and the position drops linearly. When the punch die 7 contacts the work W (point P1 in the figure), the lowering of the upper table 9 is temporarily stopped, so that the value of the linear scale 21 does not change and the position feedback pulse RP stops. This is due to the gap between the gears, so-called backlash, as shown in FIG. Therefore, the amount of position deviation increases, so
The speed increases from the equation. In the figure, the change point of the position of the upper table 9 is not so clear, but the change point of the speed is clearly seen. As a result, the changing point of this speed is used as the reference point for the plate thickness measurement. Then, when the upper table 9 starts descending again, the speed returns to the original speed again.

The experimental results of the above control are shown in FIG. 4, and it can be seen that the changing points of the speed are clear as described above.

As described above, the reference point for plate thickness measurement, that is, the point where the tip of the punch die 7 contacts the upper surface of the work W can be accurately detected. On the other hand, since the lower surface position of the work W coincides with the upper end of the die mold 3, the upper table 9 position (referred to as the lower surface position of the work) when the tip of the punch mold 7 is located at the upper end position of the die mold 3. Is a known value. Therefore, the plate thickness of the work W can be accurately obtained from the difference between the reference point position and the work bottom surface position.

Thus, the upper table 9 position and the upper table 9 detected by the internal position detecting means 22 provided in the AC servomotor 17 for moving the upper table 9 up and down.
The positional deviation from the position of the upper table 9 detected by the linear scale 21 provided outside the vehicle is calculated, and the upper table speed is calculated based on the calculated positional deviation. Measure the work thickness. For this reason, the reference point is clearly determined as compared to the case where the change point of the torque of the AC servomotor 17 is used as the reference as in the conventional measuring method, so that the plate thickness with high accuracy can be obtained even when the plate thickness is thin. You can measure.

In the above embodiment, the case where the upper table 9 is lowered to perform bending is described, but the present invention is not limited to this, and the same applies to the case where the lower table 5 is raised to perform bending. ..

[0023]

The plate thickness measuring method and measuring device in the bender according to the present invention are constructed as described above, and the ram position detected by the internal position detecting means provided in the driving means for moving the ram up and down. And the position deviation between the ram position detected by the external position detecting means provided outside the ram. Then, the ram speed is obtained based on the obtained position deviation, and the plate thickness of the work is measured with reference to the point where the ram speed changes. Therefore, as in the case of the conventional measurement method, the reference point is clearly determined as compared with the case where the change point of the torque of the driving means is used as the reference, so that the plate thickness can be measured with high accuracy even when the plate thickness is thin. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a plate thickness measuring method in a bender according to the present invention.

FIG. 2 is a graph showing temporal changes in ram position and ram speed during bending.

FIG. 3 is a schematic explanatory view showing backlash in a ball screw.

FIG. 4 is an experimental result showing changes in the ram position, the torque of the AC servo motor, and the rotation speed of the AC servo motor with respect to time.

FIG. 5 is a perspective view showing a bender using the plate thickness measuring method according to the present invention.

6 is a side view as seen from the direction of arrow VI in FIG.

[Explanation of symbols]

 1 Bender 3 Die Die 5 Lower Table (Fixed Table) 7 Punch Die 9 Upper Table (Ram) 15 NC Device (Control Unit) 17 AC Servo Motor (Drive Means) 21 Linear Scale (External Position Detecting Means) 22 Internal Position Detecting means 25 Position control unit (calculation unit) W work

Claims (2)

[Claims] 1. A method for measuring plate thickness in a bender in which a command pulse from a control unit controls a drive unit to move a ram up and down to perform bending, and an internal position detection unit provided in the drive unit detects the plate thickness. The position deviation between the ram position and the ram position detected by the external position detection means provided outside the ram is calculated, the ram speed is calculated based on the calculated position deviation, and the point at which the ram speed changes is used as a reference. A plate thickness measuring method in a bender, which is characterized by measuring a plate thickness of a work. 2. A ram provided with a punch die or a die die so as to be movable up and down, a die die opposed to the punch die or the die die, or a fixed table equipped with the punch die. And a drive unit for moving the ram up and down, and a control unit for controlling the drive unit, the bender being equipped with an internal position detection unit for detecting the position of the ram, and an external unit. The external position detecting means for detecting the position of the ram from the external position detecting means, and the control part for calculating the ram speed by comparing the ram position detected by the internal position detecting means with the ram position detected by the external position detecting means. A thickness measuring device in a bender, which is provided in the section.