JP3692261B2 - Bottom dead center correction device by servo press load - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bottom dead center correction device by detecting a load in a servo press that uses an AC servo motor or a linear servo motor as a drive source and moves a slide up and down by a screw mechanism. This is effective when you want to improve product accuracy by press molding by correcting bottom dead center in response to variations in molding load caused by uneven hardness of workpieces.
[0002]
[Prior art]
Servo press bottom dead center compensator is a servo press frame, screws and other structural members due to molding load fluctuations, bottom dead center fluctuations resulting from deformation of the mold, servo press moving parts heat generation and molding die Various improved devices have been developed in order to cope with the fluctuations in the bottom dead center resulting from the deformation of the respective parts due to the heat generation of and to correct these fluctuations.
[0003]
As one of the devices, the distance from the upper surface of the bed or bolster to the lower surface of the slide is directly measured with a linear scale to correct the variation of the bottom dead center caused by the deformation due to the molding load of the structural member and the deformation due to heat. There is one that corrects the variation of the length one after another.
[0004]
The improved device corrects not only the deformation of the servo press structural member but also the variation of the bottom dead center due to the deformation of the mold. For example, the workpiece to which the upper die punch is fed on the lower die There is an apparatus according to the invention of the inventor that detects a touch point in contact with a material, measures the distance from the upper surface of the bed or bolster to the lower surface of the slide at the time of detection, and successively corrects the variation of the distance. With this device, it is possible to correct for changes in the plate thickness of the workpiece.
[Problems to be solved by the invention]
[0005]
Among the above-described conventional techniques, in the former method of correcting the variation of the bottom dead center due to the deformation of the servo press structural member or mold due to the forming force or heat, the bottom dead center accuracy is maintained at 5 to 10 microns. Can do. Further, in the latter method, the method of correcting the variation of the bottom dead center by adding the method of correcting the variation of the bottom dead center due to the change in the thickness of the workpiece, the bottom dead center accuracy can be improved by several microns. .
[0006]
However, there remains a problem that it is not possible to correct the bottom dead center variation caused by the variation of the molding load due to the variation in the hardness of the workpiece. The work material usually uses a coil material, but even if it is a coil material manufactured in a well-controlled situation with respect to plate thickness and hardness, it should not be constant at the beginning, middle and end of winding of the coil. Therefore, it is desired to improve the product accuracy by preventing the variation of the molding amount due to the variation of hardness, further improving the bottom dead center accuracy from the conventional 5 to 10 microns.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a bottom dead center correction device using a servo press load capable of correcting a variation in bottom dead center due to deformation of a structural member of a servo press and a mold caused by a variation in hardness of the workpiece. Is to provide.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, in the present invention, first, a slide from the upper surface of a bed or a bolster is used as a bottom dead center correction device by detecting a load in a servo press that uses a servo motor that can be numerically controlled as a drive source to move the slide up and down. A scale detector that detects the distance to the bottom surface (hereinafter referred to as “slide position”) and outputs an electrical position signal, and a current value supplied to the servomotor in correspondence with the load value of the slide. A current detector to be detected and an NC control device for controlling the vertical movement of the slide by controlling the current value supplied to the servo motor in accordance with a preset slide motion.
[0009]
Then, the NC control unit may store the set value of the load value and the slide position, respectively, either the slide position location is input from the load value or the scale detector slides obtained from the load detector When the set value is reached, the difference generated between the other value and the other set value is obtained, and the set bottom dead center of the slide is determined based on the bottom dead center correction value corresponding to the previously stored difference. The point is corrected, and the slide is lowered to the corrected bottom dead center and formed .
[0010]
In such a bottom dead center correction device, the NC control device, said slide load value is have you at the time it reaches the set value set Me pre, slide position outputted from the scale detector was set Me pre Position If it is higher than that, it is determined that the hardness of the workpiece is high, and the set bottom dead center of the slide is corrected by the correction value to be lowered and lowered to the corrected bottom dead center. If less than determines that the hardness of the workpiece is low, the setting bottom dead center of said slide is corrected the only correction value high, it may be one which is lowered to the bottom dead point as the correction.
[0011]
Meanwhile, the NC control device, the slide position scale detector outputs are have you at the time it reaches the slide position set Me pre, than the load value load value is set Me pre calculating the NC control device If it is larger, it is determined that the hardness of the workpiece is high, and the set bottom dead center of the slide is corrected to be lower by the correction value and lowered to the bottom dead center ,
Conversely, when lower than the load value set in advance, be those lowering determined that the hardness of the workpiece is low, to the bottom dead center set bottom dead center of the slide with high corrected by the correction value May be .
[0012]
Furthermore, the NC control device detects the touch point where the upper die that is lowered with the slide contacts the workpiece supplied on the lower die at the rising edge of the current value output by the current detector, and detects this. Based on the output of the scale detector at that time , an error from the reference value of the thickness of the workpiece is obtained, and the correction value of the set bottom dead center of the slide is further corrected by the amount of the error to obtain a bottom dead center. or it may be Ru is lowered to. That is, the set bottom dead center of the slide is corrected in accordance with the change in the plate thickness of the workpiece.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 to FIG. 4 show an embodiment of a bottom dead center correcting device by detecting a load in a servo press according to the present invention. FIG. 1 shows a configuration of a bottom dead center correction device by detecting a load in the servo press 1. The slide 3 guided to the frame 2 of the servo press 1 so as to be movable up and down is supported by the frame 2 and is engaged with the lower end portion of the screw shaft 4 which is movable up and down and rotatable.
[0014]
Further, the slide 3 is driven by a servo motor 5 through rotation of the screw shaft 4. The servo motor 5 is driven and controlled by the current supplied from the NC controller 6. The current circuit 7 is provided with a current detector 8 that detects a current value supplied to the servomotor 5. Further, a scale detector 9 made of a linear scale or the like for detecting the slide position is installed on the frame 2 so as to be close to the slide 3. The scale detector 9 can detect the position of the slide 3 in units of 1 micron.
[0015]
FIG. 2 shows a control system of the servo motor 5 that controls the vertical movement of the slide 3. The NC control device 6 includes an NC device 6A that outputs a preset NC signal, and a driver 6B that drives and controls the servo motor 5 by outputting a current corresponding to the NC signal output from the NC device 6A. Yes.
[0016]
Further, the NC device 6A is fed back with a current value detected by the current detector 8 and indicating a slide load and a signal indicating the slide position detected by the scale detector 9 and is output as a correction value obtained by calculating them. The current corresponding to the NC signal is output to the driver 6B and used for rotation control of the servo motor 5.
[0017]
The molding load of the slide 3 may be calculated by attaching a strain meter to the frame 2 and inputting the output of the strain meter due to the molding load into the NC device 6A. Or you may detect by another method.
[0018]
An upper mold 10A is attached to the lower surface of the slide 3, and a lower mold 10B is attached to the upper surface of the bolster installed on the bed of the frame 2. At the touch point where the upper die 10A reaches the workpiece supplied on the lower die 10B, the current detector 8 detects the rise of the current value due to the start of molding, and inputs it to the NC device 6A to rotate the servo motor 5. Used for control.
[0019]
FIG. 3 shows a servo press 1 according to the embodiment described above. The slide 3 is guided up and down by guide bars 11 provided at four places on the lower surface thereof by guides 12 provided on the bed portion of the frame 2 and can be moved up and down. Since the lower end portion of the screw shaft 4 rotatably supported by the frame 2 is installed on the slide 3, it engages with the screw 3A.
[0020]
A timing pulley 14 attached to the upper end portion of the screw shaft 4 is connected to a timing pulley 15 attached to an output shaft of a servo motor 5 fixed to the frame 2 and a timing belt 16 to transmit the rotation. An encoder 17 is directly connected to the servo motor 5, and a rotation angle signal from the encoder 17 is fed back to the NC device 6A and used for rotation control of the servo motor 5.
[0021]
Next, a detailed bottom dead center correction method in the servo press 1 will be described. The bottom dead center correction method for the change in the hardness of the workpiece by the detection of the first load is as follows. First, the slide 3 descends to start forming, and the load value of the slide 3 calculated by the NC device 6A is set in advance. When the load value is reached, the slide position detected by the scale detector 9 is compared with a preset slide position.
[0022]
If the detected slide position is higher than the set position, it is determined that the hardness of the workpiece is higher than the reference hardness, and a difference in the slide position corresponding to the difference from the reference value of the hardness is detected to detect the slide 3 The set bottom dead center is corrected to be low, and the slide 3 is lowered to the corrected bottom dead center and molded. Incidentally, the load value and the slide position to be set in advance, determines the data which was molded in advance hardness reference value and the reference value differs from the workpiece in use and stored in the NC device 6.
[0023]
On the contrary, when the slide position is lower than the set position, it is determined that the hardness of the workpiece is lower than the reference hardness, and the difference in the slide position corresponding to the difference from the reference hardness value is detected to set the slide 3 The bottom dead center is corrected to be higher, and the slide 3 is lowered to the corrected bottom dead center and molded. Note that the bottom dead center correction value corresponding to the difference from the hardness reference value is determined by the hardness reference value and data obtained by molding a workpiece different from the reference value in advance, as in the case of the set value described above. . By this correction, the bottom dead center accuracy of the slide 3 can be set to 1 to several microns.
[0024]
The bottom dead center correction method for the change in the hardness of the workpiece by the detection of the second load is as follows. First, the slide 3 descends to start forming, and the slide position detected by the scale detector 9 is a preset slide position. At this point, the load value calculated by the NC device 6A based on the current value detected by the current detector 8 is compared with a preset load value.
[0025]
If the calculated load value is higher than the preset load value, it is determined that the hardness of the workpiece is higher than the standard hardness, and the slide is detected by detecting the difference in the load value corresponding to the difference from the standard hardness value. The set bottom dead center of 3 is corrected so as to be lowered, and the slide 3 is lowered to the corrected bottom dead center and molded. Note that the preset load value and slide position are determined based on the hardness reference value and data obtained by molding a workpiece different from the reference value in the same manner as described above.
[0026]
On the contrary, when the load value is lower than the set load value, it is determined that the hardness of the workpiece is lower than the reference hardness, and the difference in the load value corresponding to the difference from the reference hardness value is detected, and the slide 3 The set bottom dead center is corrected so as to increase, and the slide 3 is lowered to the corrected bottom dead center and molded. In addition, the hardness of the workpiece is often slightly higher at the front and rear ends of the coil material, and the intermediate portion is almost uniform and may be partially low.
[0027]
The standard hardness of the work material is the hardness of the substantially uniform part in the middle of the coil, the hardness is judged to be high or low, and the bottom dead center correction value corresponding to the fluctuation of the load value due to the difference in hardness is as described above. In the same manner as described above, it is determined based on a hardness reference value and data obtained by molding a workpiece different from the reference value. Also by this correction, the bottom dead center accuracy of the slide 3 can be set to 1 to several microns.
[0028]
So far, the plate thickness of the workpiece has been described as being uniform, but the plate thickness of the coil material may vary slightly. If the plate thickness changes, the molding load value at the same bottom dead center position also changes. Therefore, first, the touch point at which the upper mold 10A reaches the workpiece supplied on the lower mold 10B while the slide 3 is descending is detected at the rising point of the current detector 8 when the current value is formed. .
[0029]
If the slide position detected by the scale detector 9 at this time is a reference value, that is, if the plate thickness is a reference value, the slide is lowered to a preset bottom dead center without correcting the set bottom dead center of the slide 3. Mold. On the other hand, if the slide position is higher than the reference value, it is determined that the plate thickness is thick, the set bottom dead center of the slide 3 is corrected, and the slide 3 is lowered to the corrected set bottom dead center and molded. On the other hand, when the slide position is lower than the reference value, it is determined that the plate thickness is thin, the set bottom dead center of the slide 3 is corrected, and the slide 3 is raised to the corrected set bottom dead center.
[0030]
The correction of the set bottom dead center according to the change in the plate thickness of the workpiece can be performed in combination with any of the bottom dead center correction methods for the change in the hardness of the workpiece by the detection of the first and second loads. Can be used. Accordingly, the combination can be selected and used by the setting device provided in the NC control device 6 of the servo press 1.
[0031]
FIG. 4 shows a slide motion until the slide 3 descends and rises. The X axis is a time (SEC) axis and the Y axis is a slide position (MM) axis, and the curve shown as the slide motion before correction is a curve with a bottom dead center accuracy of 5 to 10 microns according to the conventional example. .
[0032]
In addition, the slide motion curve in which the correction for the change in the hardness of the workpiece by the load detection and the correction by the plate thickness is performed is a curve as indicated by a dotted line. Accordingly, the bottom dead center accuracy can be improved to 1 to several microns as described above by the correction. The correction amount is displayed on the screen as “current correction value”.
[0033]
In the above, one embodiment of the method for detecting the load by the current of the servo motor has been described. However, for example, the actual load may be detected by a load cell or the like. That is, it goes without saying that the configuration and the detailed design change based on the above technical idea are all included in the present invention.
[0034]
【The invention's effect】
As is clear from the above description, according to the present invention, the bottom dead center accuracy by the bottom dead center correction device that detects the change in the slide position and corrects the set bottom dead center is 5 to 10 microns. On the other hand, the correction of the set bottom dead center due to the variation of the molding load can correct the fluctuation of the set bottom dead center due to the deformation of not only the servo press but also the mold, and the bottom dead center accuracy It can be said that the effect that can be improved to 1 to several microns is extremely large.
[Brief description of the drawings]
[Fig. 1] Configuration diagram of the bottom dead center correction device by the load of the servo press [Fig. 2] Block diagram showing the control system of the servo motor of the servo press [Fig. 3] Front view of the main part of the servo press [Fig. Illustration of press slide motion 【Explanation of symbols】
1 is a servo press, 2 is a frame, 3 is a slide, 3A female screw, 4 is a screw shaft, 5 is a servo motor, 6 is an NC control device, 6A is an NC device, 6B is a driver, 7 is a power circuit, and 8 is a current. Detector, 9 is a scale detector, 10 is a mold, 10A is an upper mold, 10B is a lower mold, 11 is a guide rod, 12 is a guide, 13 is a bolster, 14 is a timing pulley, 15 is a timing pulley, and 16 is a timing. Belt, 17 is encoder, 18 is load cell, etc.

Claims (4)

In the bottom dead center correction device by detecting the load in the servo press that gives the slide a lifting motion using a servo motor that can be controlled numerically,
(A) a scale detector that detects the vertical position of the slide and outputs an electrical position signal;
(B) a current detector for detecting a current value supplied to the servo motor or a load detector such as a load cell;
(C) A current value to be supplied to the servo motor is controlled in accordance with a preset slide motion, and the lift movement of the slide is controlled.
Leave each stored set value of the load value and the slide position, at the time when either the slide position location input from the load value or the scale detector slides obtained from the load detector reaches the set value The difference generated between the other value and the other set value is obtained, the set bottom dead center of the slide is corrected based on the bottom dead center correction value corresponding to the difference stored in advance , and the slide is NC controller that lowers to the corrected bottom dead center and molds ,
Bottom dead center correction device according formed Katachini heavy detection in a servo press, characterized in that to equip. The NC controller is
It said slide load value is have you at the time it reaches the set value set Me pre, wherein when the output slide position of the scale detector is higher than the position set Me pre determines that the hardness of the workpiece is high , Lower the set bottom dead center of the slide by the correction value and lower it to the bottom dead center ,
On the contrary, when the position is lower than the preset position, it is determined that the hardness of the workpiece is low, and the set bottom dead center of the slide is corrected to be higher by the correction value and lowered to the bottom dead center. A bottom dead center correction device by detecting a molding load in the servo press according to claim 1. The NC controller is
The slide position scale detector outputs are have you at the time it reaches the slide position set Me pre, when the load value calculated in the NC control device is greater than the load value set Me pre is the workpiece It is determined that the hardness is high, the set bottom dead center of the slide is corrected to be lower by the correction value and lowered to the bottom dead center ,
Conversely, when the load value is lower than a preset load value, it is determined that the hardness of the workpiece is low, and the set bottom dead center of the slide is corrected by the correction value to be lowered to the bottom dead center. A bottom dead center correction device by detecting a molding load in the servo press according to claim 1. The NC controller is
The touch point where the upper die that descends with the slide contacts the workpiece supplied on the lower die is detected at the rise of the current value output by the current detector, and the scale detector at the time of detection is detected. based on the output, obtains the error from the reference value of the thickness of the workpiece, and wherein Rukoto is lowered to the bottom dead center by further correcting the correction value of the slide set bottom dead center in minutes of the error A bottom dead center correction device by detecting a molding load in the servo press according to claim 1.

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