JPH06304662A - Method for controlling bending position of work in nc press brake - Google Patents

Abstract

PURPOSE:To enable a bending, in which a highly accurate bending angle is required, by bending with a bending position for a programmed thickness compensated for a bending position suitable for the determined thickness. CONSTITUTION:A distance from the die table C of a position controllable ram D is registered as an absolute position. A punch B with its length set is attached to the ram D. A die A with its length set is attached to the die table C, and the operation of the ram D is controlled during the bending operation. When the tip end of the punch B is abutted on the work E that is loaded on the die A and the ram D is stopped, the position of the ram D at that point of time is measured. From this measured value and the set length of the punch B and the die A, the thickness t1 of the work E is predetermined. Then, the bending position R for the programmed thickness is compensated before bending for the bending position S that is suitable for the predetermined thickness, and the bending is performed. Thus, a wrong program input and the consequential generation of defective products are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC press brake, in which the thickness of a work plate material is measured immediately before bending, and the bending position is calculated based on the measured value to perform bending work. The present invention relates to a method for controlling a bending position by adding a correction to the previously programmed bending position.

[0002]

2. Description of the Related Art Conventionally, in the bending work by NC press brake, the bending work is carried out by a pre-programmed work plate thickness. This method is
If the dimensional accuracy of the work is high, the plate thickness is uniform, and there is no variation, there will be no particular problem.However, if the work has low dimensional accuracy and there is variation in the product thickness, the target angle according to the programmed thickness will be obtained. Even if the work is performed at the calculated bending position in order to realize, the accuracy of the bending angle of the bent work is unavoidably low.

For this reason, conventionally, since the bending angle is measured after bending and the bending position is recalculated, or the operator empirically corrects and sets the bending position, the work efficiency is poor. Therefore, there is a problem that the bending angle accuracy becomes unstable.

[0004]

In view of the above-mentioned prior art, the present invention automatically measures the work thickness of the NC press brake during bending even if the work thickness varies. However, it is an object to provide a method of controlling a bending position by calculating a bending position suitable for this measured value.

[0005]

The present invention has been made for the purpose of solving the above-mentioned problems, and its constitution is N
In the C press brake, the position of the ram whose position is controllable is registered as the absolute position, the punch having the set length is attached to the ram, and the die having the set length is attached to the die table. When the ram stops when the tip of the punch comes into contact with the work placed on the die and the ram stops, the position of the ram at that time is measured and the measurement is performed. The wall thickness of the work is calculated from the value and the set length of the punch and die, and the bending position based on the programmed plate thickness before bending is set to the bending position suitable for the calculated plate thickness. It is characterized in that it is corrected and bent.

[0006]

The distance from the die table of the ram whose position can be controlled by a hydraulic servo or the like is registered as an absolute position, and a punch having a set length is attached to the ram.
On the other hand, since the die table has a die with a set length set, if the tip of the punch comes into contact with the work placed on the die during the bending operation and the ram stops, then By measuring the position of the ram in, the work plate thickness is calculated, the bending position suitable for the measured plate thickness calculated above is recalculated, and the bending position is controlled It is possible to perform highly accurate bending.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.
Figure 1 shows the positional relationship between the die table and the ram, which are initially set to measure the work thickness, the length of the punch attached to the ram, and the length of the die attached to the die table. Fig. 2 is a diagram showing a state in which the thickness of the work is being measured, and Fig. 3 is a bending suitable for the measured thickness of the work with respect to the bending position programmed before the bending work. It is a figure which shows a place which corrects so that it may become a position, and controls a bending position.

In the figure, A is a die having a length m set and attached to a die table C, D is a ram whose position can be controlled by a hydraulic servo or the like, and a distance z from the die table C is absolute. The location is registered as a location. B is the ram D
The length z is set and the punch is attached. The distance z and the lengths m and n are preset for measuring the plate thickness t of the work E.

In order to measure the plate thickness of the work E placed on the die A, the ram D is operated and controlled so as not to apply a bending pressure as shown in FIG. The die table C of the ram D at the time Q when the tip of the punch B is brought into contact with the work E and the ram D is stopped by the reaction force from the work E.
The actual plate thickness t1 of the work E can be calculated by the following formula by measuring the distance z1 from. In addition, P indicates the time when the ram D stops because the tip of the punch B contacts the work E when the plate thickness of the work E is t. t1 = z1− (m + n)

Further, in order to control the bending position suitable for the actual plate thickness of the work E, the work position calculated by the above with respect to the bending position R by the plate thickness t programmed before the bending process is controlled. Only t2 needs to be corrected so that the bending position S is suitable for the plate thickness t1 of E. The correction amount t2 is t2 = S−R.

As described above, the actual plate thickness t1 of the work E is measured, and the bending position by the plate thickness t programmed before bending is corrected by t2 to obtain the plate thickness t1.
Since the bending is performed by controlling the bending position S to a suitable bending position S, even if the work E has a variation in plate thickness, stable bending can be performed with high angular accuracy.

[0012]

As described above, the present invention registers the position of a ram whose position is controllable from the die table as an absolute position, attaches a punch having a set length to the ram, and When a die with a set length is attached to the bull and the operation of the ram is controlled during the bending operation and the tip of the punch comes into contact with the work placed on the die to stop the ram, The wall thickness of the work was calculated by measuring the position of the ram and subtracting the sum of the set lengths of the punch and the die from this measured value. Even if there is, it can be detected well and the actual thickness can be measured. Also, by correcting the bending position of the work to a position suitable for this actual thickness and bending it, bending with high angular accuracy Is possible. Further, by actually measuring the plate thickness of the work during bending, it is possible to confirm the input of the plate thickness value set by the program before the processing, so that it is possible to prevent an erroneous program input and generation of a defective product due to this.

[Brief description of drawings]

FIG. 1 is a positional relationship between a die table and a ram, which are initially set to measure a work thickness, a length of a punch attached to the ram, and a length of a die attached to the die table. The figure which shows it.

FIG. 2 is a diagram showing a state in which the plate thickness of the work is being measured.

FIG. 3 is a diagram showing a bending position controlled by correcting the bending position programmed before bending to a bending position suitable for the actual plate thickness of the work.

[Explanation of symbols]

A die B punch C die table D ram E work m Die setting length n Punch setting length z Distance from die die table to ram z1 The tip of the punch contacts the work and the ram stops. Distance from die table to ram t when work is done t Work thickness t1 Measured work thickness R R Bending position when plate thickness is t S Bending position when plate thickness is t1

Claims (3)

[Claims] 1. In an NC press brake, the position of a ram whose position is controllable is registered as an absolute position, and a punch having a set length is attached to the ram and the length of the die table is adjusted. Attach the set die and control the operation of the ram during the bending operation.When the tip of the punch comes into contact with the work placed on the die and the ram stops, change the ram position at that time. The thickness of the work is calculated from this measured value and the set length of the punch and die, and the bending position based on the thickness set by the program before bending is calculated as the above calculated thickness. A method for controlling a bending position of a work in an NC press brake, which is characterized in that the bending position is corrected to a suitable bending position. 2. The bending position control method according to claim 2, wherein the position of the ram is controlled by a hydraulic servo. 3. The bending position control method according to claim 1, wherein the ram is stopped by the reaction force of the work when the tip of the punch comes into contact with the work placed on the die.