JPS60120404A - Origin returning device - Google Patents

Abstract

PURPOSE:To return a movable element to the origin safely and quickly by discriminating whether the stop position is within an allowable range of origin return or not and stopping the origin returning operation if the stop position is outside the allowable range. CONSTITUTION:The first movable element 13 is freely slidably placed on a bed of a machine tool 10, and the second movable element 14 is slidably placed on this element 13. A tool T is set to a main shaft of the third movable element provided in the front of this element 14 to subject a work W on a work supporting table to required working. Movable elements are controlled by numerical controllers. These movable elements 13 and 14 are detected by absolute position detectors 18 and 19 and are returned to the origin automatically. With respect to this returning to the origin, it is discriminated whether stop positions of movable elements 13 and 14 are within the allowable range of origin return or not by a disriminating means 1, and the returning operation is started if they are within the allowable range, but otherwise, the returning operation is stopped by control of a control means 2.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an origin return device that automatically returns a movable element supporting a workpiece or a tool to an origin detected by an absolute position detector. .

<Prior art> In general, machine tools machine a workpiece W by moving a tool T located at the origin P1 along a line shown by an arrow, as shown in FIGS. 4 and 5, and If an abnormality occurs during the process, the tool T is stopped at that position and the subsequent operation is stopped.

However, in this abnormally stopped state, the machine tool cannot be inspected, and it is necessary to return it to the origin PL where the workpiece W and tool T do not interfere.

When returning to the origin, if the stop position of the tool T is within the allowable range for returning to the origin indicated by diagonal lines, for example P2, there is no obstacle between the stop position P2 and the origin P1, and the tool T moves linearly toward the origin P1. This allows you to return to the origin.

However, if the stop position of the tool T is outside the home return permissible range, for example P3, there is a risk of interference with the workpiece W if the tool T moves linearly from the stop position P3 toward the home point P1.

In this way, depending on the stop position of the tool T, the tool T and the workpiece W
Since there is a risk of interference with the original point P1, the return operation to the origin point P1 must be performed while being supervised by an operator, which has the drawback that the return operation to the origin point takes time.

<Object of the Invention> The present invention has been made to eliminate such conventional drawbacks, and its purpose is to safely and quickly return to the origin without causing interference between the tool and the workpiece. .

<Structure of the Invention> In order to achieve the above object, the present invention automatically moves the movable element 13.14 to the origin detected by the absolute position detector 18.19 in response to a return-to-origin command, as shown in FIG. In the origin return device configured to return the movable element to the origin, the origin return device includes a determining means 1 for determining whether the stop+L position of the movable element 13° 14 is within the allowable range for returning to the origin, and as a result of this determination, the movable element 13.L) Features include a home return operation control means 2 that starts the home return operation when the stop position of 14 is within the home return allowable range and prevents the home return operation when it is outside the home return allowable range. That is.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2, 10 is a machine tool, and a first movable element 13 consisting of a table is placed on a head 11 of this machine tool 10 so as to be slidable in the X direction.

A second movable element 14 made of a column is placed on the first movable element 13 so as to be slidable in the Y direction, and a third movable element 15 made of a spindle head is placed on the front surface of the second movable element 14.
is guided and supported so that it can be raised and lowered. This third movable element 1
A main shaft 16 is rotatably supported on the main shaft 16. i and T are attached. These first. Second. Third
Movable elements 13°, 14.15 are each servo motor MX
, M.Y.

The absolute position detector 1B is relatively moved by the MZ and the amount of movement is determined by an absolute encoder.

Detected by 19.20. Such first. Due to the relative movement of the second and third movable elements 13, 14.15, the tool T
performs required processing on the workpiece W supported on the workpiece support stand 17.

Servo motor MX provided in each axis assembly of the machine tool 10,
A drive circuit 21.2 is connected to MY and MZ by the numerical control device 20.
The pulses are distributed via 2.23. Numerical control device 2
0 is composed of a microcomputer 25 and a memory 26, and this memo IJ26 stores a cutting program and a return-to-origin program for machining the workpiece W.

In order to process a workpiece W as shown in FIG. 4 using this machine program, the microcomputer 25 instructs each servo motor MX, MY,
When a pulse is output to MZ and the tool T is stopped due to an abnormality, the origin return operation is performed from the stopped position toward the origin according to the origin return program. In this origin return program, for each machining surface, for example, the origin return permissible range shown in the shaded area in Fig. 4 is determined by each coordinate data Sl, S2.
, S3. S4. It is programmed as S5, and it is determined whether the stop position is within the allowable range for returning to the origin specified by the coordinate data, and the one-point return to the origin is performed.

Next, specific processing operations of the microcomputer 25 will be explained based on the flowchart of FIG. 3 and the operation diagram of FIG. 4.

In the normal operating state of the machine tool 10, the microcomputer 25 reads the machine tool program from the memory 26, and controls each servo motor MX, MY, MZ based on this machine tool program.
Send out the necessary pulses for the first. Second. Third movable element 1
3.Move 14.15. This causes tool T to move to the fourth position.
The workpiece W is moved relative to the origin P1 shown in the figure while drawing a trajectory shown by an arrow, and the workpiece W is subjected to necessary machining.

If an abnormality occurs in the machine tool 1o such as a broken tool during this machining, the numerical control device 2o detects this abnormality and stops sending pulses to each servo motor MX, MY, MZ, and stops the operation of the machine tool 10. will be stopped. In this stopped state, the machine tool 1o cannot be inspected, so the operator presses the return-to-origin button before starting this inspection. Upon receiving this command, the microcomputer 25 executes the process shown in FIG.

That is, at the same time as the origin return command is input, the microcomputer 25 reads the Y-axis of the stop position and the absolute coordinate value in the Y-axis direction from the output of the absolute position detector 18.29, and then determines the stop position from those values as shown in FIG. It is determined whether the return to origin is within the permissible range indicated by diagonal lines (steps 100 to 102).

If the stop position is within the return-to-origin tolerance range indicated by P2, for example, then the stop position is the Y-axis.

It is determined whether the origin P1 is on the + side of each Y axis, and if it is on the + side, pulses are sent in one direction, and if on the - side, pulses are sent to the servo motors MX and MY in the child direction, respectively, and the absolute position is determined. As soon as the origin P1 is detected by the detectors 18 and 19, the sending of this pulse is stopped, and the origin return operation is completed (steps 103 to 106).

However, if the stop F position is outside the home return allowable range indicated by P3, there is a risk that the workpiece W and tool T will interfere if the home return operation is performed, so a home return impossible command is output (step 117). . Using this signal, the operator can individually move the tool T to within the allowable home return range, and then output the home return command in the same manner as described above, thereby quickly performing the home return operation.

<Effects of the Invention> As detailed above, the present invention provides a home return device with a determining means for determining whether or not the stop position of the movable element is within the home return allowable range, and as a result of this determination, a The configuration includes a home return operation control means that starts the home return operation when the stop position is within the home return allowable range and prevents the home return operation when the stop position is outside the home return allowable range. It has the advantage of being able to safely and quickly return to the origin without interfering with the

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the entirety of the present invention, Fig. 2 is a block diagram showing an embodiment of a numerical control device according to the invention and a machine tool controlled by the same, and Fig. 3 is a flow chart showing the operation of a microcomputer. , FIG. 4 is an explanatory diagram of the operation of the present invention, and FIG. 5 is a cross-sectional view taken along the line -V in FIG. 4. DESCRIPTION OF SYMBOLS 1... Determination means, 2... Home return operation control means, 1
3,14.15...1st. Second. Third movable element, 1B
, 19.20... Absolute position detector, T... Tool, W
...Workpiece, MX, MY. MZ...Servo motor. Patent applicant Toyota Machinery Co., Ltd. 9-

Claims (1)

[Claims] (1) In a home return device that automatically returns a movable element to the home position detected by an absolute position detector in response to a home return command, the home return device automatically returns the movable element to the home position. a determining means for determining whether or not the position is within the permissible range; and as a result of this determination, when the stop position of the movable element is within the permissible range for home return, the home return operation is started, and when the stop position of the movable element is outside the permissible home return range, the home position return operation is performed. What is claimed is: 1. A home-point return device characterized by comprising a home-point return operation control means for preventing the home-point return operation.