JPH05150819A - Malfunction detecting method at the time changing tool or work - Google Patents

Abstract

PURPOSE:To confirm whether a tool or work change operation is executed correctly or not before starting the change operation, in an NC machine tool for executing an automatic tool change or an automatic work change by utilizing a motion of a feed shaft for NC working. CONSTITUTION:Before starting a tool or work change operation, a feed shaft is moved by a prescribed amount from a reference position, an actual position of the feed shaft after the movement, and a scheduled position to which the shaft is to be moved at the time of normal operation are compared, and when both the positions coincide with each other, it is decided that there is no hindrance in a normal change operation and the change operation is executed. On the other hand, when both the positions do not coincide with each other, it is decided that a malfunction occurs, and there is the possibility of a collision, damage, etc., of the tool, etc., the execution of a tool or work change program is suspended, and an alarm is generated.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a malfunction detecting method for exchanging a tool or a work in an NC machine tool, and more particularly to a moving shaft and a work for exchanging the tool or the work. The present invention relates to a malfunction detection method when a tool or a work shared with an axis is replaced. FIG. 3 shows an NC equipped with an automatic tool changer.
Shows a milling machine. A table 22 has left and right (X-axis) and vertical (Z-axis) NC feed shafts with respect to the base 20, and a tool spindle 24 has front and rear (Y-axis) NC feed shafts. The lower end of the tool spindle 24 has a shape in which the tool T is mounted, and its clamp device is 26. A so-called egg pot type tool magazine 28 accommodating a plurality of tools T in the front-rear direction is provided at the left end of the table 22, and is covered with an openable / closable cover 30. This NC milling machine performs an automatic tool change operation on an empty tool spindle 2
A case where the tool T in the tool magazine 28 is mounted on the No. 4 will be described as an example. First, the Z axis is positioned at a predetermined position, and the cover 30 is opened. The X axis is moved to the right and the Y axis is also moved, and the tool T is positioned so as to be directly below the tool spindle 24. When the Z axis rises and the tool T is fitted with the tool spindle 24, the tool T is clamped by the clamp device 26.
Is gripped by the tool spindle 24. Then, when the X axis moves to the left, the tool T is removed from the tool magazine 28, the cover 30 is closed, and processing is started. NC like this
The automatic tool change is performed by utilizing the movements of the feed axis for machining, X, Y and Z. FIG. 4 is a plan view of a horizontal machining center equipped with an automatic work changing device. The table 32 has a left and right (X axis) NC feed shaft and a column 34 with respect to the base
Is the front and rear (Z axis) NC feed axis, and the tool spindle 36 is the column 3
Each has an NC feed shaft that moves up and down in 4 (Y axis). The work is fixed on the pallets 38 and 40, and the pallets 38 and 40 are alternately placed on the table 32.
The work on the pallet is processed. On the other hand, stockers 42 and 44 are provided in front of the table 32. The pallet 38 is on the stocker 42, and the pallet 40 is on the stocker 4.
4 can be placed on. An automatic work exchange, that is, a pallet exchange operation in this machining center will be described. When the machining of the work of the pallet 38 on the table 32 is completed, the X axis is moved to the right and the pallet 38 is positioned so as to stop immediately in front of the stocker 42. The pallet 38 is slid on the stocker 42 on the horizontal plane by the grip claws 46 which are driven back and forth by an air cylinder or the like. After that, the X-axis moves to the left, and the table 32 is positioned in front of the stocker 44. The pallets 40 on the stocker 44 are transferred onto the table 32 by the grip claws 48, and the pallet exchange is completed. In this way, the automatic workpiece exchange is performed by utilizing the movement of the feed shaft X for NC machining. Such a system is called a shuttle type work changing device. The operations for automatic tool change and automatic work change are instructed by the NC program. That is, the automatic tool change and the automatic work change process are executed together with machining by a series of NC programs. In the so-called egg pot type automatic tool change or shuttle type automatic work change shown in FIGS. 3 and 4, the NC feed axis is provided with control information such as a mirror image and scaling. In some cases, it may be necessary to replace the tool or the work during the operation. In this case, in the NC program created in advance, the control information such as the mirror image and scaling is once invalidated before commanding the tool change or the work change, and the control information is re-commanded after the command for the tool change or the work change. It was annoying. If neglected, there is a concern that the feed axis may move in the opposite direction or move in an unnecessarily large amount when performing a tool change or work change operation, leading to a serious accident.
The same can be said when the operator manually inputs the control information such as the mirror image and scaling from the operation panel. In this case, the control information is automatically invalidated before the tool change or the work change operation. There was no way to get or give an alarm. As described above, conventionally, there have been problems that the creation of the NC program is complicated and there is a risk of causing an accident. Therefore, an object of the present invention is to provide a method for surely and quickly detecting whether or not a tool or work is normally replaced before the tool or work is automatically replaced by a simple method. In order to solve the above-mentioned problems, a malfunction detecting method at the time of exchanging a tool or a work according to the present invention utilizes an operation of a feed shaft for NC machining to automatically change a tool. Alternatively, in an NC machine tool for automatic work change, at the start of a tool or work change program, after positioning the feed shaft at a predetermined reference position, the feed shaft is moved by a predetermined amount, and the feed shaft position after this movement is performed. When,
The movement is compared with an expected position to be originally moved, and when the two positions do not match, the execution of the tool or work replacement program is interrupted and alarm information is output. According to the present invention, the feed shaft is moved from the reference position by a predetermined amount before the tool or work changing operation is started, and the actual position of the feed shaft after the movement and the planned position to be moved during the normal operation are set. If both positions match, it is judged that there is no hindrance to the normal replacement operation, and the replacement operation is performed.If the two positions do not match, there is a risk of malfunction, tool collision, damage, etc. Judge, interrupt the exchange program,
By generating the alarm, it is possible to prevent the cancellation of the control information before the exchange operation and to ensure safe and reliable exchange. The present invention will now be described with reference to the drawings. FIG. 1 is a configuration block diagram showing an NC device to which a tool or work replacement malfunction detecting method according to the present invention is applied, by way of example of a case of tool replacement. The NC data 1 recorded on a recording medium such as a paper tape is read by the reading unit 2, is interpreted, and is sent to the calculation unit 3. The calculation unit 3
Upon receipt of the NC data, a predetermined calculation is performed and the calculation data is supplied to the positioning command unit 4 for positioning each axis. A control signal for positioning is sent from the positioning command unit 4 to the servo unit 5, and the feed motor 6 is controlled via the servo function. The current position information is supplied from the feed motor 6 to the display unit 10 and displayed. When the NC program includes a tool replacement command, the computing unit 3 performs the following computation to detect a malfunction of the replacement. That is, at the start of the tool change program, a command signal for moving each feed shaft by a predetermined amount (a minute amount) is sent to the positioning command unit 4, and the feed motor 6 is driven through the operation of the servo unit 5. On the other hand, the calculation unit 3 sends to the comparison unit 7 a sum signal of the reference position indicating the planned position information of each feed shaft to be moved and the minute movement amount. A signal indicating the current position information from the feed motor 6 is supplied to the comparison unit 7, and the planned position information, which is the sum signal from the calculation unit 3, is compared with the current position information from the feed motor 6, and both are compared. When the information matches, the tool change operation unit 8 is informed that the normal tool change operation is possible because the control information such as the above-mentioned mirror image is not included during the operation of the tool change program and the tool change operation is possible. The exchange operation is performed. When the comparison unit 7 detects a discrepancy between the two pieces of information, the control information such as the mirror image is still valid, and the feed axes are not moved to the normal positions when the tool is exchanged, so that the tool exchange operation is performed as it is. There is a risk of tool damage. Therefore, in this case, the subsequent tool changing operation is not performed, but a mismatch signal is sent to the alarm output unit 9 and an alarm is output by visual / audible means to that effect. FIG. 2 shows a flowchart of a processing procedure for detecting a malfunction at the time of changing the tool. Referring to FIG. 2, when the NC program interprets the automatic tool change command, the tool change subprogram starts (step S
1) First, in FIG. 3, for example, the Z axis is positioned at a reference point (step S2). As this reference point, a point such as the lowermost position where there is no work interference is set. Next, each feed axis is moved by a predetermined amount from this reference point (step S
3) Read the current position of each feed axis (step S
4). The predetermined amount in step S3 is preferably selected to be about 100 times the minimum movement unit, and the movement of the feed axis is in the X, Y, and Z axis directions. In this manner, it is determined whether or not the current position read when each feed shaft is moved by a predetermined amount is equal to the position indicated by the planned position (reference point + commanded predetermined amount) (step S
5) If they are not equal to each other, an alarm is generated so that it is possible to output a visual / audible means indicating that it is dangerous to perform the tool change program processing as it is (step S7).
With that, the subsequent processing is stopped. When it is determined that they are equal in step S5, it means that the feed axis is moved normally, so the tool change operation is started (step S6), and the subprogram is ended (step S).
8). In this way, since the sequence in which the malfunction detection operation is always performed is inserted at the beginning of the tool exchange subprogram, this detection is performed every tool exchange operation. Although the above description of the embodiment has been made with respect to the tool replacement process, it goes without saying that the present invention is naturally applicable to not only the tool replacement but also the work replacement process. As described above, the method for detecting malfunctions during tool or work replacement according to the present invention allows the feed shaft to be moved from the reference position by a predetermined amount before the start of tool or work replacement, and after the movement. The actual position of the feed axis is compared with the planned position to move during normal operation.If both positions match, it is judged that there is no hindrance to the normal replacement operation, the replacement operation is performed, and both positions match. If there is no error, an alarm is generated because it is judged that there is a risk of collision, damage, etc. of tools etc., so before the replacement operation of the function such as mirror image and scaling set during normal processing program processing It is possible to prevent cancellation cancellation. Moreover, these operations can be performed quickly with a simple configuration.
Safe and reliable replacement is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration block diagram of an NC device to which an embodiment of a method for detecting a malfunction when a tool or a work is replaced according to the present invention is applied. FIG. 2 is a flowchart showing a processing procedure of a malfunction detecting method at the time of tool or work replacement according to the present invention. FIG. 3 is a front view of an NC milling machine having an egg pot type automatic tool changing device. FIG. 4 is a plan view of a horizontal machining center having a shuttle type automatic tool changer. [Explanation of symbols] 1 NC data 2 Reading unit 3 Computing unit 4 Positioning command unit 5 Servo unit 6 Feed motor 7 Comparison unit 8 Tool change operation unit 9 Alarm output unit 10 Display unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B23Q 17/22 Z 8612-3C

Claims (1)

What is claimed is: In an NC machine tool that performs automatic tool change or automatic work change using the movement of the feed axis for NC machining, when the tool or work change program is started, the feed axis is set to a predetermined reference position. After positioning, the feed shaft is moved by a predetermined amount, and the position of the feed shaft after this movement is compared with the planned position to be originally moved by the movement. If the two positions do not match, the tool or work replacement program The method for detecting malfunctions when exchanging tools or workpieces is characterized by suspending the execution of and executing alarm information.