JPH0628837B2 - Machine tool with return-to-origin function - Google Patents

Description

TECHNICAL FIELD The present invention relates to a machine tool having a home position return function.

<Prior art> With a machining center type machine tool, it is detected that a machining abnormality has occurred during machining due to overload of the spindle motor, etc., and if such abnormality is detected, the machining is interrupted when the abnormality occurs. However, after that, the original position is returned to the original position by a manual operation so that the tool is replaced and the processed workpiece is discharged.

<Problems to be Solved by the Invention> As described above, in the conventional machine tool, there is a problem that unmanned operation is difficult because the original position must be returned to the original position after the machining is interrupted.

In particular, as shown in FIG.
If a machining error is detected in a state where the tool T cannot be moved to, the original position cannot be restored simply by moving the tool T in the axial direction, and after manually shifting the position of the tool in the radial direction, I had to do a return to home position.

<Means for Solving Problems> The present invention is for solving the above-mentioned problems, and is a radial movement command for moving a machining tool in the radial direction from the machining hole to restore the original position and an axial position for moving the machining tool. Storage means for storing a program for returning to the original position consisting of an axial movement command for returning, abnormality detection means for detecting an abnormality occurring during machining, and detection that the machining tool is engaged in the machining hole Engaging detection means for, and in response to the abnormality detected by the abnormality detection means, one of the radial movement command or the axial movement command of the original position return program is executed by the numerical control means, An original that executes the other of the radial movement command and the axial movement command in response to the engagement detection means detecting that the machining tool is engaged in the machining hole. A position return control means C is provided.

<Operation> When a machining abnormality is detected by the abnormality detecting means, the home position return control means operates in response to this, and the numerical control means issues a radial movement command or an axial movement command of the home position return program. And executing the other of the radial movement command or the axial movement command in response to the engagement detection means detecting that the machining tool is engaged in the machining hole. Even if the tool cannot be extracted from the machining hole unless the tool is moved in the direction orthogonal to the axis of the machining hole, the original position can be automatically returned.

<Example> An example of the present invention will be described below with reference to the drawings. In FIG. 2, reference numeral 10 is a bed of the machine body 1, and this bed 1
A table 11 on which the workpiece W is placed is guided movably in a direction perpendicular to the paper surface (X axis direction), and a spindle head 12 is movably guided in a vertical direction (Z axis direction). The column 13 is guided so as to be movable in the left-right direction (Y-axis direction). The table 11 is moved in the X-axis direction by the servomotor 14 fixed on the bed 10, and the spindle head 12 is attached to the servomotor 15 attached to the rear end of the bed 10 and the upper portion of the column 13. The servo motor 16 is used to move in the Y-axis direction and the Z-axis direction.

These servo motors 14 to 16 are drive units 5
It is connected to the numerical control device 2 via the, and is rotationally driven by the distribution pulse output from the numerical control device 2. Further, between the drive unit 5 and the servo motors 14 to 16, meter relays 22a to 22 for detecting that each axis servo motor 14 to 16 is overloaded.
c is provided.

Reference numeral 17 denotes a spindle that is vertically mounted on the spindle head 12 and is driven to rotate by a spindle motor 18, and a tool T in a tool magazine is selectively mounted by a tool changing device (not shown).

When the load torque acting on the tool T is within the allowable value, it is determined whether the load torque acting on the tool T is within the allowable value or not depending on the magnitude of the current flowing between the spindle motor 18 and the power supply line AC. Is provided with an abnormality detection circuit 19 for outputting an abnormality detection signal.

Reference numeral 2 denotes a publicly known numerical control device. In the internal memory 2a of the numerical control device 2, in addition to the processing program input by the tape reader 30 and the like, FIGS.
A pair of home position return programs ORP1 and ORP2 shown in
Is remembered. This home position return program ORP
Of the ORP2, the home position return program ORP1 is
The Z-axis original position is returned from the beginning, and the skip function code G31 is programmed in the block N200 in order to interrupt the feed when the tool T cannot be pulled out from the machining hole.

On the other hand, the original position return program ORP2 continuously performs the X-axis original position return, the Y-axis original position return, and the Z-axis original position return, but the original position return command is programmed in blocks N302, 304, 306. Is the sequence control device 3
When a skip signal is sent from the device, a skip function code G31 for interrupting the sending is programmed at that time.

Further, the blocks N303, 3 next to the blocks N302, 304 programmed with the original position return command in the X and Y axis directions
In 05, return programs X- [A * # 1] and Y- [A * # 1] for returning in the direction opposite to the original position direction are programmed. In this program, A indicates a constant, and # 1 indicates a parameter name whose value is increased in block N301.

A sequence control device 3 is connected to the numerical control device 2, and one of a plurality of programs is selected and executed by a command from the sequence control device 3. That is, when the program control command is output in the state where the sequence control device 3 outputs the sequence number corresponding to any of the first blocks of the plurality of programs, the numerical control device 2 causes the numerical control device 2 to output the given sequence number. The block corresponding to is searched, and after that, the numerical control program after the searched block is executed when the start command is given.

The sequence control device 3 monitors the output of the abnormality detection circuit 19 when the processing of the workpiece W is started, and when an overload occurs during the processing and the abnormality detection signal is output from the abnormality detection circuit 19. A sequence program is created so as to perform the home position return process shown in the flowchart of FIG.

That is, when the occurrence of an abnormality is detected, the sequence controller 3 supplies a reset signal to the numerical controller 2 to interrupt the machining program being executed (50). And
Thereafter, the head block number 200 of the home position return program ORP1 is sent to the numerical control device 2 to instruct the program search (51), and thereafter, a start command is given to the numerical control device 2 to execute the home position return program ORP1. Let
As a result, the numerical control device 2 causes the home position return program O
The first programmed G31, F20 of RP1,
Z100 is executed to perform pulse distribution for moving the tool T in the Z-axis direction at the command speed.

The sequence control device 3, after the feeding is started,
Whether or not the servomotor 16 is overloaded depending on whether or not the overload signal is sent from the meter relay 22C is checked until the spindle head 12 returns to the original position (54). When the spindle head 12 returns to the original position without sending the overload signal and the program completion signal is sent from the numerical controller 2, the original position returning process is completed here. When the home position return is started from such a state and an overload signal is sent from the meter relay 22C, at that time, a skip signal is sent to the numerical controller 2 to interrupt the sending, and # 1000 is also sent.
Set the address output to 1 (55) and return to the original position program O
Execute RP2.

That is, the sequence control device 3 sends the sequence number 300 of the first block of the home position return program ORP2 to the numerical control device 2 to send the home position return program ORP2.
2 is searched (56), and then the execution of the home position return program ORP2 is commanded (57). In the head block N300 of the home position return program ORP2, # 1
While the output at address 000 is 1, blocks N301 to N301
Command WHILE [# 1000] to repeat program 07
EQ1] DO1 is programmed, and a command to increase the content of the parameter # 1 by 1 is programmed in the block N301. G28, G31, and X0 for returning the tool T to the origin of the X-axis are programmed in the block N302. When this program is read, the numerical control device 2 moves the tool T to the origin of the X-axis in the X direction. Distribute the pulse to the axis. As a result, the tool T moves in a direction orthogonal to the axis of the machined hole Wa, and the tool T moves in the machined hole W.
When the different parts of a are engaged, their movement is stopped. In this way, when the tool T engages with the machining hole Wa of the workpiece W and stops, the drive current of the servomotor 14 increases, and the meter relay 22a operates to output the overload signal OLX. Then, in response to the operation of the meter relay 22a, the sequence control device 3 sends a skip signal to the numerical control device 2 to interrupt the home position return movement currently being executed.

As a result, the return program X- [A * # 1] stored in the block N303 is executed. At this time, since the initial value of the parameter # 1 is zero, the return movement amount in this case is zero, and the return operation (operation in the direction opposite to the origin direction) is not performed. Further, following this, based on the programs of blocks N304 and N305, the home position return and return operations to the Y axis are executed. Also in this case, the return operation is not performed because the parameter # 1 is zero. Then, based on the program of the block N306, the original position return in the Z-axis direction is performed.

By such a return movement to the original position in the X-axis direction and the Y-axis direction, the tool T is normally moved from the machined hole Wa by moving the tool T in the Z-axis direction as shown by a chain double-dashed line in FIG. Since it becomes possible to extract, subsequently, this is followed by the original position return commands G28, G3 in the Z-axis direction of the block N306.
1 and Z0 are executed, the tool T is the machining hole W of the workpiece W.
The original position is returned in the Z-axis direction after being separated from a. When it is confirmed that the return to the original position in the Z-axis direction is completed in this way, the sequence controller 3 sets the output of # 1000 to 0. As a result, the numerical control device 2 jumps to block N308 and returns to the original position return program ORP2.
Ends the execution of.

On the other hand, in the case where the home position return movement in the Z-axis direction cannot be performed by only one movement in the XY directions described above, that is, the overload of the servo motor 16 is detected by the meter relay 22c when the home position is returned in the Z-axis direction. In the case (59), the skip signal is transmitted (60), the process returns to the block N301 again, and 1 is added to the parameter # 1. Therefore, in the blocks N303 and N305, the returning operation is performed by A in the X-axis direction and the Y-axis direction. After that, as described above, the original position return in the Z-axis direction is performed, and when the original position return is still not possible, 1 is added to the parameter # 1, and therefore the return operation in the X-axis direction and the Y-axis direction is performed. Is doubled [A × 2].

After that, the original position return operation is executed again in the Z-axis direction,
By repeating these operations, the tool T is separated from the machined hole Wa and returned to the original position.

In this way, when the tool T cannot be returned to the original position by the original position return program ORP1, the original position return program ORP2 first sets the tool T on the X axis and the Y axis.
If the tool T still cannot be returned to the original position by moving it in the direction of the origin of each axis, then move the tool T by a predetermined amount in the direction opposite to the direction of the origin of the X-axis and the Y-axis, while moving the tool T. By returning to the original position, when the abnormality is detected, the tool T is positioned at a position where the original position can be returned in the Z-axis direction regardless of the positional relationship between the tool T and the machining hole Wa. become able to.

By doing so, when it is detected that the tool T is engaged with the machining hole Wa and stopped, the radial movement and the axial movement of the tool T with respect to the machining hole Wa are switched and executed, and the original position is set. Will be returned to. Then, when the processing for returning to the original position is completed, the workpiece W is automatically replaced and the machining is continued.

<Effect of the Invention> As described above, in the present invention, when the above occurs during machining, one of the command to move the machining tool in the radial direction in the machining hole and the command to move it in the axial direction is executed. After that, when it is detected that the machining tool is engaged in the machining hole, the other of the command to move in the radial direction and the command to move in the axial direction is executed to return to the original position, and Even if the tool cannot be detached from the work piece only by moving, it is possible to automatically return to the original position regardless of the shape of the drilled hole, and there is an advantage that unmanned operation can be performed more efficiently.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram for clarifying the present invention, and FIGS.
FIG. 4 shows an embodiment of the present invention, and FIG. 2 is a schematic side view of a machine tool with a block diagram of a control circuit.
FIG. 3 is a flowchart showing the operation of the sequence control device 3 in FIG. 2, and FIGS. 4 (a) and 4 (b) show the original position return program ORP1 stored in the memory 2a of the numerical control device 2 in FIG. FIG. 5 is a view showing ORP2, FIG. 5 is a view showing an engagement relationship between a workpiece and a tool in a machining state, and FIG. 6 is an enlarged view taken along the line VI-VI in FIG. 1 ... Machine body, 2 ... Numerical control device, 2a ... Memory, 3 ... Sequence control device, 12 ... Spindle head,
17 ... Spindle, 18 ... Spindle motor, 19 ... Abnormality detection circuit, 22a-22c ... Meter relay, T ... Tool,
W ... Workpiece.

Claims (1)

[Claims] 1. A machine tool having an original position return function, wherein a radial movement command for moving a machining tool from a machining hole in the radial direction to return to the original position and a shaft to move in the axial direction to return to the original position. Storage means for storing a program for returning to the original position including a direction movement command, abnormality detection means for detecting an abnormality occurring during machining, and engagement for detecting engagement of the machining tool in the machining hole In response to the detection means and the abnormality detection means detecting an abnormality, the numerical control means executes one of the radial direction movement command and the axial direction movement command of the original position return program, and the engagement is performed. A home position return control hand that executes the other of the radial movement command and the axial movement command in response to the detection means detecting that the machining tool is engaged in the machining hole. Machine tool equipped with the original position return function, characterized in that it comprises and.