JPS61229421A - Bending method for plate like body - Google Patents

Abstract

PURPOSE:To increase the bending accuracy by measuring the pressure quantity and bending angle of the punch which is on the way of bending and by measuring the bending angle of after removing the load. CONSTITUTION:A bending fulcrum 2 and punch 3 are provided on a press and bending angle detecting device 4 and punch pressure quantity measuring instrument 5 are arranged as well. When the punch 3 is pushed in by the press, the pressure quantity is displayed by punch pressure quantity measuring instrument 6. On the other hand a movable base 8 is pressed to the material 1 to be worked via rod 9 and the rotary angle thereof as well is displayed on the right and left displayers. When the push force is removed with the retreat of the punch 3, the deformation of the material 1 to be worked is restored by the spring back. By this work the springback quantity against the pressure quantity of a fixed quantity can be estimated correctly. With this method therefore the bending accuracy is increased because of the bending angle of after the springback being able to be found with its correct correction from the pressure quantity of the punch 3.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for bending plate-like objects such as panel tube bending and plate bending by pressing.

<Prior art and problems to be solved by the invention> In conventional press bending, a panel tube or plate is placed on a metal surface, and a punch is used to press the center of the plate to bend it. The bending angle is adjusted by adjusting the amount of push of the punch through the gap between the backing plate above the workpiece.

FIG. 6 is an explanatory diagram of the conventional method. A workpiece 1 is set on a bending fulcrum 2, and a punch 3 is moved downward to bend the workpiece 1. The amount of bending of the workpiece l is adjusted by the amount of movement of the punch 3, and after bending with a slightly smaller amount of movement, a template with the final shape is applied to bend it.) While checking the condition, gradually bring it to the final shape. A number of methods have been adopted.

For this reason, the machining work is highly dependent on the operator's intuition, and only certain operators can perform the work, and the bending time is long, with repeated pushing of small widths to avoid excessive bending. 4. Some bending correction was required.

Accordingly, a seventh object of the present invention is to provide a method for bending a plate-shaped object which not only improves the bending accuracy but also facilitates the work and does not take a long time.

Means for Solving the Problems〉 The present invention achieves the above object by measuring the amount of punch depression during bending and measuring the bending angle of the workpiece in press bending of a plate-like object. The present invention is characterized in that the bending angle of the workpiece after loading is measured, and the final push-in amount of the punch is estimated based on the results of the above-described method to obtain an accurate bending angle of the workpiece.

<Example> Here, the present invention will be explained in detail. In Figures 1 to 5, the press, etc.

It has a bending fulcrum 2, a punch 3, and a bending angle detector ft.
4 and a punch pushing amount measuring device 5. The punch push amount measuring device 5 is equipped with a punch push amount measuring device 6 such as a direct-acting pulse oscillator, a differential transformer, and a potentiometer at a position facing three punches (the part where there is space for installing the measuring device 6 is preferably placed on the punch side). If there is space and it does not interfere with the work, it can be mounted on the punch side.) The amount of depression of the punch 3 from the beginning to the end of bending is measured.

The bending angle detector [4] includes a pin 7 incorporating an angle detector (not shown) as shown in FIG. This rod 98 has an air cylinder 10 for lightly pressing the workpiece 1 and a rod support part 11, which are arranged on both sides of the punch 30. An angle detector such as a rotary encoder or a potentiometer is attached to the movable base 8 via a pin 78, and the pin 7 fixed to the clamp 9 and the movable base 8
Measure the rotation angle with. In addition, since the movable table 8 moves toward the punch 3 side as the workpiece 1 is bent, rollers are used to prevent any force from acting in the lateral direction on the edge 9. In addition, as the movable base 8, it is also possible to use a link mechanism as shown in FIG. 3Gl)lb).

[With the above structure] To explain the method of this embodiment, punch 3 is used.
When the punch is pushed into the press 8, the punch push amount measuring device 6 displays the punch push amount Fi on the display (not shown). on the other hand,
As the workpiece 10 is bent, the movable base 8 is pressed against the workpiece 1 by the rod 9 and rotates along the workpiece 1, so this rotation angle can be calculated separately for the left and right sides or by adding the right and left sides together. Displayed on the display.

Therefore, if a CRT or the like is provided as a display, the X-axis is the pushing force, and the Y-axis is the bending angle, the relationship between the punch push amount and the bending angle can be displayed and visually expressed.

Furthermore, when the punch 3 is moved backward to remove the pushing force, the deformation returns due to the springback of the workpiece l, and the output of the angle detector also changes. The amount of springback changes depending on variations in the strength and shape of the workpiece, and by knowing the amount of springback when a certain amount of punch is pushed in, it is possible to estimate the amount of punch push to obtain the final shape. becomes. In other words, the bending angle when the punch 3 is pushed in is determined by the radius of the punch 3, the radius of the fulcrum 2, and the center-to-center distance between the two centers, and the relationship between the pushing amount of the punch 3 and the bending angle 7 is determined geometrically. Ru. On the other hand, the bending angle after springback after eliminating the pressing force from the punch 3 is as follows.

It is expressed as the sum of the angle detectors placed on the left and right sides of punch 3.
Ru. Therefore, as shown in FIG. 4, the punch pushing amount P and angle θ at the time of pressing are obtained.

In this way, springback information can be obtained by unloading at a certain pushing position and measuring the ξ bending angle. Therefore, as shown in FIG. 5, once the load is unloaded at a slightly smaller bending angle than the final bending angle '/711F'', the bending angle after springback will be:

The value #E is sufficiently satisfying even if the pushing amount is approximated by a second approximation.
becomes. Furthermore, if you want accuracy, you can use a 2nd or 3rd order approximation by examining the changes during the springback two or three times, or in practical terms, you can use a trend line from past data. It may be corrected using that value. In any case, it is only necessary to determine the gradient of springback correction. This amount of springback is.

For example, it changes slightly depending on the welding sensitivity and thickness, so it is important to remove the load once during the process, check the bending angle under no load, and make corrections in order to maintain bending accuracy.

In this way, once the pushing amount of the punch 3 is determined, the bending angle of the workpiece after springback can be easily corrected.
Since it is estimated with sufficient accuracy, bending can be performed by making it possible for the operator to read it on a digital display, or by specifying the push amount in the case of automatic operation. There are two angle detectors on both sides of the punch 30, but if the width of the plate becomes wider, there may be a difference at both ends, so it is desirable to measure on both sides.

<Effects of the Invention> Due to the above-mentioned effects, machining with good surface accuracy can be easily carried out. As a result, correction work after bending can be eliminated, and one work only needs to be instructed numerically, which requires sufficient experience. It is possible to do it without it, and it can be done very well.

[Brief explanation of drawings]

Figures 1 to 5 show embodiments of the present invention; Figure 1 is a configuration diagram of the device; Figure 2 is a top view of the bending angle detection device;
Fig. 3 G1) ←) is a configuration diagram showing two types of OIJ links of the movable table, Figs. 4 and 5 are characteristic curves of the bending angle and pushing amount, and Fig. 6 is the conventional bending process. FIG. Inside the drawing. 2 is the bending fulcrum. 3 is punch. 4 is a bending angle detection device. 5 is a punch pushing amount measuring device. 7Fi pin. 8 is a movable platform. 9 is a rad. 10 is an air cylinder.

Claims (1)

[Claims] In press bending of a plate-shaped object, the punch depth during bending is measured, the bending angle of the workpiece is measured, and the bending angle of the workpiece after unloading is measured, and based on these results. A method of bending a plate-like object by estimating the final depth of the punch to obtain an accurate bending angle of the workpiece.