JP3824038B2 - Electric vendor home position return method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides an origin return for an electric bender that performs bending of a plate material using an upper mold mounted on a ram having three or more drive shafts driven by an electric motor and a lower mold mounted on a fixed table. The present invention relates to a method and apparatus.
[0002]
[Prior art]
Conventionally, a ram (movable table) is driven by an electric motor, and a plate material is bent by an upper mold mounted on the ram and a lower mold mounted on a fixed table arranged opposite to the ram. Formula vendors are known. This electric vendor usually has a plurality of servo axes (generally referred to as “DS axes”) for controlling the positioning of the ram in the vertical direction.
[0003]
By the way, in this type of electric vendor, the position where the ram is moved downward and in contact with the fixed table in a state where no mold is mounted is defined as the mechanical origin of the ram. Further, the position where the rams are moved downward and the dies come into contact with each other with the upper die and the lower die attached to the ram and the fixed table is defined as the working origin of the ram. The mechanical origin is set by determining the servo origin of the DS axis servo system. Here, the servo origin of the DS axis is at a position where the ram is raised from the position of the work origin, and the positional relationship (relative distance L) between the servo origin and the machine origin is a unique value determined at the time of assembling the machine. However, it is an invariable value except in special cases. When the electric vendor is started, the servo origin of each DS axis is first established (hereinafter referred to as “origin return”) after the power is turned on. When this return to origin is completed, the origin offset value (corresponding to the relative distance L) stored in the counter of each axis is substituted to establish the coordinate system, thereby establishing the machine origin and the work origin.
[0004]
Generally, an electric vendor is composed of a plurality of control axes as DS servo axes in order to control ram ascending / descending, and it is impossible to shift to bending work unless the origin return work of these multiple axes is performed. This home return operation is extremely important work performed at the start of the electric vendor.
[0005]
Next, the origin return sequence of the conventional electric servo will be described with reference to FIG.
[0006]
As shown in the figure, an origin deceleration dog 51 and a position detector 52 having a Z pulse are mounted on the ram, an origin deceleration limit switch for detecting the origin deceleration dog 51 on the machine body side, and the position A detector for detecting the detector 52 is fixed. During the return to origin operation, the ram is raised at a preset approach speed, and when the origin deceleration limit switch detects the origin deceleration dog 51 during this elevation, the ram is decelerated to a preset creep speed and the origin deceleration dog 51 When it is out of the range, the search for the Z pulse (Z1 pulse to Z4 pulse) of the position detector 52 is started. After this, when a Z pulse is detected, the motor stops decelerating, returns by an excessive amount, and stops at the Z pulse position. At this time, when the position near the Z pulse is reached, the origin offset value is substituted into the counter to continue to return to the Z pulse position. This origin return sequence is performed simultaneously for a plurality of ram drive axes (DS axes).
[0007]
Further, as a prior art related to the present invention, there is one disclosed in JP-A-7-93034. In this prior art, in a positioning control device that positions two axes in parallel and drives each axis to position a load attached to those axes, when the encoder of the first axis outputs a timing signal The count value of the first counter is set to 0, and when the encoder of the second axis outputs a timing signal, the count value of the second counter is set to a preset predetermined offset value, The movable body is moved by rotating the first and second motors until the count value of the second counter becomes zero.
[0008]
[Problems to be solved by the invention]
However, the conventional origin return method shown in FIG. 6 may cause the following problems, particularly when there are three or more DS servo axes (for example, four axes). In other words, if origin return is started at the same time for the four axes when the power is turned on, the position of the Z pulse (Z1, P2, Z3, Z4) on each axis is not strictly the same height, so the lowest Z pulse (Z3 pulse in the example of FIG. 6) is detected first, and its axis (DS3 axis) decelerates and stops to return to the position of the Z3 pulse. On the other hand, since the Z pulse has not been detected for the other three axes, the home position return operation is continued to try to raise the ram. Next, the ram rises to detect the next Z pulse (Z1 pulse in the example of FIG. 6), and the DS1 axis decelerates and stops to return to the position of the Z1 pulse. In this way, the DS1 axis to DS4 axis will complete the home return in order from the lowest Z pulse position, and the axis that has completed the home return will stop at the Z pulse position and the home return is complete. Axis that is not doing will continue to rise. As a result, the ram receives a downward external force from the DS axis whose origin return has been completed, and receives an upward external force from the DS axis whose origin return has not been completed, and is distorted. In addition, the control system for each DS axis cannot accurately return to the position of each Z pulse due to the influence of disturbance from the other DS axes, causing a shift in the coordinate system.
[0009]
In the technique disclosed in the above publication (Japanese Patent Laid-Open No. 7-93034) cited as the prior art related to the present invention, the number of drive shafts is limited to two, and each of these axes Since the two-step process of detecting the origin pulse and substituting the reference value and the offset value during the movement of the moving object is necessary, there is a problem that the processing time is required and the control accuracy is inferior. In addition, when such a processing method is applied to a system having three or more drive axes, control is inevitably caused.
[0010]
The present invention has been made to solve such problems, and an origin return method for an electric vendor capable of performing origin return operation with high accuracy without applying an excessive external force to the ram and its The object is to provide an apparatus.
[0011]
[Means for solving the problems and actions / effects]
In order to achieve the above object, the method of returning to the origin of the electric vendor according to the first invention is as follows:
An origin return method for an electric bender that performs bending of a plate material by an upper mold mounted on a ram having three or more drive shafts driven by an electric motor and a lower mold mounted on a fixed table. ,
(A) a first step of driving all drive shafts in the ram ascending direction at a preset approach speed based on the origin return activation signal;
(B) a second step of decelerating the ram ascent speed by driving all the drive shafts to a creep speed smaller than the approach speed when a deceleration signal is detected during ram ascent at the approach speed;
(C) a third step of starting detection of a reference position for each drive shaft after a predetermined time has elapsed since the deceleration to the creep speed or after a predetermined distance of movement;
(D) a fourth step of detecting the reference position for each drive axis and storing the reference position of the corresponding axis at the time of detection;
(E) a fifth step of simultaneously decelerating and stopping all the drive shafts after the detection of the reference positions in all the drive shafts; and (f) a deceleration stop position of each drive shaft at the deceleration stop position and the reference position. Based on this, a sixth step of performing origin correction for each drive shaft is provided.
[0012]
In the present invention, when an origin return start signal is issued when performing an origin return operation, all the drive shafts are driven in a ram ascending direction at a preset approach speed (first step), and then decelerated during the ram ascending. When the signal is detected, the ram rising speed is decelerated to a creep speed smaller than the approach speed, and the ram rising is continued (second step). After this, after a predetermined time has elapsed since the deceleration to the creep speed or after a predetermined distance of movement, in other words, after waiting for the ram ascent speed to settle down to the creep speed, the reference position (Z pulse position) for each drive shaft is set. Detection is started (third step), and when this reference position is detected, the reference position of the corresponding axis is stored (fourth step). In this way, when the reference positions of all the drive shafts are detected, all the drive shafts are decelerated and stopped (fifth step), and the respective drive shafts are decelerated and stopped based on the deceleration stop position and the reference position. Origin correction is performed by calculating the origin correction value for each axis (sixth step). According to the origin return method of the present invention, even when applied to a system having three or more drive shafts, an excessive external force from each drive shaft is not applied to the ram, and each drive shaft is Since the reference position can be accurately detected, the origin can be returned with extremely high accuracy.
[0013]
Next, the origin return device of the electric vendor according to the second invention is:
An origin return device for an electric bender that performs bending processing of a plate material by an upper die attached to a ram having three or more drive shafts driven by an electric motor and a lower die attached to a fixed table. ,
(A) a deceleration start position detecting means for detecting a deceleration start position of the ram while the ram is rising at a preset approach speed;
(B) The detection of the reference position for each drive axis is started after a predetermined time has elapsed after the deceleration start position is detected by this deceleration start position detection means or after a predetermined distance has been moved, and the reference positions of all the drive axes are detected. A reference position detecting means for detecting completion of the operation,
(C) Drive each drive shaft to raise the ram at the approach speed, and decelerate the ram to the creep speed when the deceleration start position is detected by the deceleration start position detecting means during the increase at the approach speed. A ram drive control means for controlling the drive of the ram so as to decelerate and stop all the drive shafts when the reference positions of all the drive shafts are detected by the reference position detection means during the increase in the creep speed, and ( d) A reference position for each drive axis detected by the reference position detecting means is stored, a deceleration stop position of each drive axis is stored, and each drive axis is determined from the stored reference position and deceleration stop position. Origin correction value calculating means for calculating the origin correction value is provided.
[0014]
The origin return device for an electric vendor according to the present invention relates to a device for specifically realizing the origin return method according to the first invention. In the present invention, when performing the origin return operation, if the deceleration start position is detected by the deceleration start position detecting means while all the drive shafts are being driven in the ram ascending direction at a preset approach speed, The ram rising speed is reduced to a creep speed smaller than the approach speed, and the ram is further raised. Thereafter, after a predetermined time elapses after the deceleration start position is detected by the deceleration start position detection means or after a predetermined distance of movement, in other words, after waiting for the ram rising speed to settle to the creep speed, each reference position detection means Detection of a reference position (Z pulse position) for each drive axis is started, and when this reference position is detected, the reference position of the corresponding axis is stored. Thus, when the reference positions of all the drive axes are detected by the reference position detection means, all the drive axes are decelerated and stopped. At the deceleration stop position of each drive axis, the deceleration correction position and the reference are calculated by the origin correction value calculation means. Origin correction is performed by calculating an origin correction value for each drive axis based on the position. According to the origin return device of the present invention, even when applied to a system having three or more drive shafts, an excessive external force from each drive shaft is not applied to the ram, and each drive shaft is Since the reference position can be accurately detected, the origin can be returned with extremely high accuracy.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, a specific embodiment of a method for returning to the origin of an electric vendor according to the present invention and an apparatus therefor will be described with reference to the drawings.
[0016]
FIG. 1 is a partial perspective view of an electric vendor according to an embodiment of the present invention.
[0017]
The electric vendor according to this embodiment includes a ram (upper movable table) 1 that is driven up and down, and a fixed table (lower fixed table) 2 that is fixedly disposed facing the ram 1. A punch (upper die) (not shown) is attached to the lower portion of the fixing table 2 via a punch holding device 3, and a die (none of which is shown) is attached to the upper surface of the fixed table 2 via a die holding device.
[0018]
A pair of side frames 5, 5 are integrally provided on both sides of the fixed table 2, and a support frame 6 is provided so as to connect the upper ends of the side frames 5, 5. A plurality of (four in this embodiment) ram driving devices 7 are attached to the support frame 6, and the ram 1 is swingably connected to the lower end of these ram driving devices 7. In this way, the ram 1 is moved up and down by the operation of the ram driving device 7, whereby the plate material (work) inserted between the punch and the die is bent.
[0019]
Each ram driving device 7 transmits an AC servo motor 8 controlled by a servo control device, which will be described later, to a ball nut (not shown) via a timing belt 9 as a driving source, and a ball screw connected to the ball nut. The ram 1 connected to the ball screw 10 is driven up and down by moving the 10 up and down.
[0020]
Incremental linear encoders 11 are attached to the rams 1 corresponding to the positions of the drive shafts of the respective ram drive devices 7 (hereinafter referred to as DS1 axis, DS2 axis, DS3 axis, DS4 axis from the left side), The detector 12 is attached to the extension correction bracket 13. The detection data from the linear encoder 11 is used for position feedback control of the servo motor 8. Here, the extension correction bracket 13 is composed of two side plates 13a, 13a provided along the side frames 5, 5, and a beam 13b connecting the left and right side plates 13a, 13a. . By attaching the detector 12 of the linear encoder 11 to the extension correction bracket 13 in this way, each linear encoder 11 is not affected by deformation due to load changes of the side frames 5 and 5, and each drive of the ram 1 is driven. The absolute position for each axis can be measured. In this embodiment, the linear encoder (main body) 11 is attached to the ram 1 and the detector 12 is attached to the correction bracket 13. However, these attachment positions may be reversed.
[0021]
Further, an absolute type motor encoder (not shown) for detecting the current position of each servo motor 8 is attached to the motor shaft of each servo motor 8. The detection data from the motor encoder is used for speed feedback control of the servo motor 8.
[0022]
As shown in the schematic diagram of FIG. 2, the ram 1 includes an origin deceleration dog 14 for instructing to decelerate the ascent speed of the ram 1 from the approach speed to the creep speed, and the ram 1 at the start of the origin return operation. An origin escape dog 15 for instructing lowering and an overtravel dog 16 (see FIG. 3) for emergency stop of the ram 1 when the ram 1 rises to the vicinity of the ascending end for some reason are mounted. On the machine body side, an origin deceleration limit switch for detecting the origin deceleration dog 14, an origin escape limit switch for detecting the origin escape dog 15, and an overtravel limit switch for detecting the overtravel dog 16 (for the limit switch) Neither of them is shown). FIG. 3 shows the positional relationship between the dogs 14, 15, and 16.
[0023]
Next, the processing sequence of the origin return control of the ram 1 in the present embodiment will be described with reference to the time chart shown in FIG. 5 by the flowchart shown in FIG.
[0024]
S1 to S2: When the origin escape limit switch is stepping on the origin escape dog 15 at the start of the origin return operation, the ram 1 is lowered until the origin escape dog 15 is released.
[0025]
S3 to S5: When the home escape limit switch is removed from the home escape dog 15, the ram 1 is raised at the approach speed V1, and it is determined whether or not the home deceleration limit switch falls within the range of the home deceleration dog 14 during this rise. To do. Then, once it is within the range of the origin deceleration dog 14, each drive shaft (DS1, DS2, DS3, DS4) is decelerated to the creep speed V0, and at the same time, the ram ascent speed settles to the creep speed V0. Start a timer that is set to wait.
[0026]
S6 to S7: When the timer expires, Z pulse detection is started while maintaining the rising speed of the ram 1. FIG. 3 illustrates a case where the lowest Z pulse is a Z2 pulse of the DS2 axis and is sequentially detected in the order of the Z1 pulse (DS1 axis), the Z3 pulse (DS3 axis), and the Z4 pulse (DS4 axis). Therefore, when the first Z2 pulse is detected, the current value of the DS2 axis at that time is stored, and the ram 1 is continuously increased at the creep speed to detect the Z pulse, and the DS1 axis, DS3 axis and DS4 axis are detected. Each Z pulse is detected and each current value is sequentially stored.
[0027]
S8 to S10: If it is confirmed that all Z pulses have been detected, all servo motors 8 are decelerated and stopped at the same time for all axes, and origin correction values are set for each DS axis at the deceleration stop position. Do. This origin correction is performed as follows. First, when the Z pulse latch signal is detected, the position information at that moment is set in the register A. When four Z pulses are detected and the four axes decelerate to a stop, the current value (deceleration stop position) for each axis is set in register B. The origin correction value is calculated using the stored values of the registers A and B and the origin offset value (position where the Z pulse should be) stored in advance. That is, the distance from the current position to the Z pulse position is obtained by subtracting the value of the register A from the value of the register B, and this calculated value is added to the origin offset value, so that the current position can be calculated on the basis of the origin offset value. Ask. The value thus obtained is substituted into the current value register to obtain the current value. By performing this operation for all axes, the origin correction value for each axis is obtained.
[0028]
According to this embodiment, even when applied to a system having three or more drive shafts, an excessive external force from each drive shaft is not applied to the ram, and the Z pulse for each drive shaft is applied. Since the position (reference position) can be detected accurately, the origin return can be performed with extremely high accuracy.
[0029]
In this embodiment, when the origin deceleration dog 14 is stepped on, each axis is decelerated from the approach speed to the creep speed and the timer is started at the same time. However, as a sequence of Z pulse search, the origin deceleration dog 14 A sequence may be set in which the length is set to an appropriate length, and after stepping on the home deceleration dog 14 and rising a predetermined distance, the Z pulse search is started when the home deceleration dog 14 is removed.
[0030]
In the present embodiment, the electric vendor having four drive shafts has been described, but the present invention can also be applied to a system having a plurality of drive shafts having two or more shafts.
[Brief description of the drawings]
FIG. 1 is a partial perspective view of an electric vendor according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a configuration of each DS axis.
FIG. 3 is a diagram illustrating a positional relationship between dogs.
FIG. 4 is a flowchart showing a processing procedure of origin return control.
FIG. 5 is a time chart of origin return control.
FIG. 6 is a time chart showing a conventional origin return sequence.
[Explanation of symbols]
1 Ram 2 Fixed Table 7 Ram Drive Device 8 AC Servo Motor 10 Ball Screw 11 Linear Encoder 12 Detector 14 Origin Deceleration Dog 15 Origin Exit Dog 16 Overtravel Dog

Claims (2)

An origin return method for an electric bender that performs bending of a plate material by an upper mold mounted on a ram having three or more drive shafts driven by an electric motor and a lower mold mounted on a fixed table. ,
(A) a first step of driving all drive shafts in the ram ascending direction at a preset approach speed based on the origin return activation signal;
(B) a second step of decelerating the ram ascent speed by driving all the drive shafts to a creep speed smaller than the approach speed when a deceleration signal is detected during ram ascent at the approach speed;
(C) a third step of starting detection of a reference position for each drive shaft after a predetermined time has elapsed since the deceleration to the creep speed or after a predetermined distance of movement;
(D) a fourth step of detecting the reference position for each drive axis and storing the reference position of the corresponding axis at the time of detection;
(E) a fifth step of simultaneously decelerating and stopping all the drive shafts after the detection of the reference positions in all the drive shafts; and (f) a deceleration stop position of each drive shaft at the deceleration stop position and the reference position. An origin return method for an electric vender comprising a sixth step of performing origin correction for each drive shaft based on the sixth step. An origin return device for an electric bender that performs bending processing of a plate material by an upper die attached to a ram having three or more drive shafts driven by an electric motor and a lower die attached to a fixed table. ,
(A) a deceleration start position detecting means for detecting a deceleration start position of the ram while the ram is rising at a preset approach speed;
(B) The detection of the reference position for each drive axis is started after a predetermined time has elapsed after the deceleration start position is detected by this deceleration start position detection means or after a predetermined distance has been moved, and the reference positions of all the drive axes are detected. A reference position detecting means for detecting completion,
(C) Drive each drive shaft to raise the ram at the approach speed, and decelerate the ram to the creep speed when the deceleration start position is detected by the deceleration start position detecting means during the increase at the approach speed. A ram drive control means for controlling the drive of the ram so as to decelerate and stop all the drive shafts when the reference positions of all the drive shafts are detected by the reference position detection means during the increase in the creep speed, and ( d) A reference position for each drive axis detected by the reference position detecting means is stored, a deceleration stop position of each drive axis is stored, and each drive axis is determined from the stored reference position and deceleration stop position. An origin return device for an electric vendor, comprising origin correction value calculation means for calculating the origin correction value.

Images