JPH0230327A - Stroke control device press brake - Google Patents

Abstract

PURPOSE:To keep the high bending accuracy of a plate material by sensing through a load sensor a time when a punch has come into contact with the plate material, computing the contact position through a stroke sensor and controlling the amount of indentation of the punch. CONSTITUTION:The punch 3 forces the plate material 1 into a groove 20 of a die to bend the plate material 1. When the punch 3 is lowered by hydraulic pressure supplied from a hydraulic ram 4 and comes into contact with the plate material 1, the value of the hydraulic pressure increases quickly. This change is detected by the load sensor 5 and the position of the punch 3 is known by the stroke sensor 7. The control computing circuit 8 requires a distance from the upper surface of the die 2 to the tip of the punch 3 and the plate thickness and computes a suitable amount of indentation. The punch 3 is lowered by a necessary amount based on the output valve of the stroke sensor 7. A necessary, accurate bending can be carried out without providing a special plate thickness measuring device.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention is a press brake machine consisting of a punch and a die, which is used to bend a long plate material at a predetermined angle.
This relates to the position control of the press brake. Conventionally, the stroke control of the press brake involves driving the punch by a stroke set based on the mechanical origin where the press brake waits. That is, as shown in FIG. 4, the stroke X is determined by lowering the tip of the punch 3 relative to the die 2 from the origin x0 to the point Xs, thereby ensuring the required pushing amount X0 of the punch 3 against the plate material 1. so that the plate material 1 is bent.

[Problem to be solved by the invention]

In this case, there is no problem if the thickness t of the plate 1 is the same as the nominal thickness, but if the plate thickness t is thinner than the nominal thickness 70, or the plate thickness t2 is thicker than the nominal thickness to. and this plate thickness t+, L2 and nominal thickness t. The pushing amount xl+X2 of the punch 3 against the plate material 1 changes from the original value x0 by the difference between the two. Moreover, originally, if the plate thickness was smaller than the nominal plate thickness, the amount of push-in would have to be increased, and if the plate thickness was larger than the nominal thickness, the amount of push-in would have to be smaller to obtain the required bending, but the opposite is true. Therefore, there is a problem in that the accuracy of the bending angle is greatly deteriorated. JP-A-61-927 discloses that the thickness of the plate 1 is measured before setting the plate 1 on the press brake, and the stroke of the press brake is corrected based on this measurement value.
However, in this case, there is a problem in that the number of plate thickness measuring devices and processes increases. The present invention has been made in view of these points, and its purpose is to adjust the press stroke to the plate material without requiring a separate plate thickness measuring device or without the need for a plate thickness measurement process. To provide a press brake stroke control device that can automatically adjust the stroke according to the thickness of the press brake and maintain high bending accuracy for the plate material.

[Means to solve the problem]

Therefore, the present invention is a stroke control device for a press brake that includes a die and a punch that pushes a plate material into the die and bends the plate material, and includes a load sensor that detects the driving load of the punch and a press stroke that detects the press stroke. The present invention is characterized in that it includes a stroke sensor and a control means that controls the amount of push of the punch based on the contact position between the punch and the plate material obtained from the output of the load sensor. [Function] According to the present invention, the thickness of the plate material is measured in real time during bending of the plate material, and the stroke is controlled according to the measured thickness, so that the amount of pushing of the plate material by the punch can be adjusted. It can be made according to the plate thickness. [Example 1] The present invention will be described below in detail based on the illustrated embodiment. A die 2 having a single-shaped groove 20, and a punch that bends the plate material 1 by pushing the plate material 1 into the W42θ of the die 2. 3, a load sensor 5 is attached to a hydraulic ram 4 for driving the punch 3, and a load sensor 5 is attached to the hydraulic ram 4 for measuring the driving load of the punch 3 by measuring the hydraulic pressure value P. A drive unit 6, which drives the punch 3 up and down by supplied hydraulic pressure, is provided with a stroke sensor 7 consisting of a linear scale or the like that measures the amount of movement of the punch 3, that is, the press stroke. The sensors 5 and 7 are connected to a control calculation circuit 8 that controls the operation of the press brake.
9 in the figure is an A/D converter inserted between the oil pressure sensor 7 and the control calculation circuit 8. In this press brake, the plate material 1 is set on the die 2, and the punch 3 is lowered by the hydraulic pressure supplied from the hydraulic ram 4 to push the plate material 1 into the groove 20 of the die 2. At this time, the hydraulic pressure P supplied from the hydraulic ram 4 to the drive unit 6 is detected by the load sensor 5.
Measure the driving load of punch 3. If the punch 3 now descends and comes into contact with the surface of the plate 1 as shown in Figure 3(a), it will be clear from the change in the hydraulic pressure P shown by the broken line in Figure 2. From this point on, the oil pressure value P rapidly increases. The control calculation circuit 8 sets the position of the punch 3 at this point as the reference X0, and
The plate thickness t is the distance from the top surface of the die 2 to the tip of the punch 3.
, find the indentation ilx suitable for this plate thickness t, and further lower the punch 3 by the above-mentioned indentation amount X from this position based on the output value of the stroke sensor 7, as shown in Fig. 1143 (b). In this way, the plate material 1 is bent. As a result, the pushing amount X given to the plate material 1 is always the optimal value for the plate thickness t of the plate material 1, and since the above measurement is performed during the bending process of the plate material 1 with the press brake, it is necessary to measure separately. It does not require any process. Note that although the case of a hydraulically driven device has been described here, similar stroke control can be performed for a device driven by another drive source by similarly detecting the driving load.

【Effect of the invention】

As described above, in the present invention, the thickness of the plate material can be measured during the whitening process of the press brake, and the plate material can be bent with a stroke according to the measured value. Thickness measurement! If! This allows the required bending to be performed accurately without requiring a separate measurement process.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an embodiment of the present invention, FIG. 2 is a time chart explaining the same operation, and FIGS. 3(a) and (b).
) is an end view of the same as above, and FIG. 4 is an end view showing the problems of the conventional example, where 1 is a plate material, 2 is a die, 3 is a punch, 5 is a negative arm sensor, 7 is a stroke sensor, and 8 is a control. The arithmetic circuit is shown. Agent Patent Attorney Mr. Ishi 1) 71i13■

Claims (1)

[Claims] (1) A press brake stroke control device consisting of a die and a punch that bends the plate material by pushing the plate material into the die, and includes a load sensor that detects the driving load of the punch, and a stroke sensor that detects the press stroke. What is claimed is: 1. A stroke control device for a press brake, comprising: a control means for controlling the pushing amount of the punch based on the contact position between the punch and the plate obtained from the output of a load sensor.