JP5219480B2 - Workpiece machining method - Google Patents

Description

The present invention relates to a numerically controlled machine tool machining a workpiece how to machine the workpiece mounted on the workpiece mount.

  When a workpiece is machined by a numerically controlled machine tool, a position as a machining reference is obtained, the origin of the workpiece coordinate system is set based on the obtained position, and the workpiece is machined. In general, a measuring means such as a touch probe is attached to the spindle of a numerically controlled machine tool, and a position to be used as a reference for processing a workpiece attached to a table or a workpiece fixture is obtained by a workpiece measuring function.

  In Patent Document 1, when centering a workpiece mounted on a workpiece mounting base, first, a touch probe is attached to the spindle, and a workpiece centering desired by an operator is selected from preset workpiece centering patterns. When a pattern is selected, a guidance screen for the workpiece centering pattern is displayed, and a numerical control device is disclosed in which the centering position is obtained by setting the origin by measuring by the operator according to the guidance screen. Patent Document 2 uses three position detectors, places a workpiece on a table that rotates in the θ direction within the XY plane, and linearly moves X and Y in two orthogonal axes. The position of the specific surface is detected by the position detector, the amount of position deviation on the table of the workpiece is calculated based on the output signal from this position detector, and the table is driven to eliminate the calculated amount of position deviation A centering device is disclosed in which a control signal for output is output from a calculation control unit to a table, and a position from a predetermined fixed point in the table is corrected.

Japanese Patent Laid-Open No. 1-301042 JP 59-152046 A

  The technique of Patent Document 1 automates the origin setting work of the workpiece coordinate system as much as possible, but when machining a workpiece with a numerically controlled machine tool, the touch probe must be attached to and detached from the spindle prior to machining, An exchange time between the tool and the touch probe and a measurement time by the touch probe are required. Therefore, there is a problem that non-processing time is extended and productivity is poor.

  The technique of Patent Document 2 detects a positional shift in the Y-axis direction with one position detector, and detects a positional shift in the X-axis direction and the θ direction with the other two position detectors. The table is centered by moving the table in the X, Y, and θ directions. This method also has a problem that the apparatus becomes complicated and time for moving the table in the X, Y, and θ directions is required, and the non-processing time is extended and the productivity is poor.

An object of the present invention is to solve the problems of the prior art, and an object of the present invention is to simplify an apparatus for obtaining a position to be used as a reference for machining a workpiece mounted on a workpiece mounting base, and to provide a workpiece coordinate system. by shortening the time to set the origin, it is to provide a workpiece machining how to improve the productivity of machining of the workpiece.

According to the present invention, in a workpiece processing method for a numerically controlled machine tool that processes a workpiece by relatively moving a tool mounted on a spindle and a workpiece mounted on a workpiece mounting base, a reference block for contacting the workpiece is provided. Position measuring means provided on the work mounting base and measuring the side surface of the work abutting on the reference block is provided on the work mounting base, and the shape and position of the reference surface for contacting the work of the reference block are stored in advance. Then, a master piece having a known size is brought into contact with the reference surface of the reference block and attached to the work mounting base, and a measuring piece of the position measuring means is brought into contact with a side surface of the master piece to measure the master piece, Measurement values are stored in advance, the work is brought into contact with the reference surface of the reference block and attached to the work mounting base, and the position measuring unit measures the measurement value. The workpiece is measured by bringing a child into contact with the side surface of the workpiece, the measured value of the stored master piece, the measured value of the workpiece, and the center position of the master piece and the center of the workpiece determined in advance for the difference between the measured values. A workpiece machining method is provided in which the position of the workpiece relative to the workpiece mounting base is obtained from the relationship with the position, the origin of the workpiece coordinate system is set based on the obtained workpiece position, and the workpiece is machined.

  A master piece having a known dimension is brought into contact with the reference surface of the reference block, the side surface of the master piece is measured by the position measuring means provided on the work mounting base, and the measured value is stored in advance. The position of the workpiece with respect to the workpiece mount is obtained by calculation using the difference from the measured value, and the origin of the workpiece coordinate system is set based on the obtained workpiece position.

  According to the present invention, when a workpiece is mounted on the workpiece mounting base, the position of the workpiece relative to the workpiece mounting base can be obtained by the contact operation of the position measuring means provided on the workpiece mounting base with the side surface of the workpiece. As a result, the non-machining time was reduced as much as possible to improve the work machining productivity. Moreover, the apparatus configuration could be simplified.

  Preferred embodiments of a workpiece machining method, a numerically controlled machine tool, and a workpiece fixture according to the present invention will be described below with reference to the accompanying drawings. First, a first embodiment will be described with reference to FIGS. A column 5 and a table 7 are provided on the bed 3 of the numerically controlled machine tool 1, a spindle head 9 is provided on the column 5, and a spindle 11 is rotatably supported on the spindle head 9. Is configured to be relatively movable in three axial directions of X, Y, and Z. The relative movement is controlled by the numerical controller 57.

  A workpiece fixture 13 is fixed on the table 7, and the workpiece fixture 13 has an scale 15 as a workpiece fixture. The work mounting surface 17 of the scale 15 is provided with a reference block 21 for contacting the side surface of the work 19 having a circular cross section and a fixing means 23 for clamping the work 19 to the scale 15. In the present embodiment, two cylindrical reference blocks 21 that are spaced apart from each other and three hydraulic fixing means 23 that press the end surface of the work 19 against the work mounting surface 17 of the scale 15 are used. . A tool 27 is attached to the tip of the main shaft 11. In FIG. 1, instead of the two cylindrical reference blocks 21, two prismatic reference blocks are arranged in a valley shape, for example, with the reference plane 45 ° upward and 45 ° upward relative to the horizontal. (See FIG. 4), or a V block having an opening angle of 90 ° arranged with the opening angle facing upward can be used (see FIG. 3).

  Next, the position measuring means 31 will be described. An inverted L-shaped probe 33 is provided above the workpiece mounting surface 17 of the scale 15 so as to be movable back and forth in the direction of the up and down arrows A in parallel with the workpiece mounting surface 17 so as to be guided and driven by an actuator 35 such as a pneumatic cylinder. It is done. The reason why the measuring element 33 is formed in an inverted L shape is that the displacement sensor 39 is arranged in parallel with the measuring element 33 to shorten the length of the position measuring means 31 in the arrow A direction. The direction of arrow A is preferably a direction of a perpendicular bisector of a straight line connecting the centers of the two reference blocks 21. In the case where the reference block is a rectangular column arranged in a V block or a valley shape, the direction of the bisector of the opening angle is preferable. In the case of a circular workpiece or a square workpiece, the center is always on a bisector, so there is an advantage that the calculation of the center position of the workpiece 19 by the calculation means 53 can be simplified.

  At the lower end of the measuring element 33, there is a contact portion 37 that contacts the side surface of the work 19. As the shape of the contact portion 37, a triangular prism is employed as shown in the present embodiment, but a flat plate, a spherical shape, or a needle shape may be employed depending on the portion to be measured. A displacement sensor 39 for measuring the displacement of the probe 33 in the direction of the arrow A above and below is provided. In this embodiment, an eddy current type non-contact sensor that measures the gap distance from the probe 33 is used. Other types of non-contact sensors and contact-type displacement sensors can also be used, and the attachment position of the displacement sensor 39 is not limited to the position of the present embodiment. The probe 33, the actuator 35, and the displacement sensor 39 are covered with a cover 41 with only the contact portion 37 exposed. An opening / closing door is provided at the lower part of the cover 41. Normally, all of the probe 33, the actuator 35, and the displacement sensor 39 are covered, and the door of the cover 41 is opened only at the time of measurement so that the contact portion 37 contacts the workpiece 19. Good.

  Next, a series of operations for attaching the workpiece 19 to the workpiece fixture 13, obtaining a position serving as a reference for machining the workpiece 19, and machining the workpiece 19 will be described. In the present embodiment, the reference position of the work 19 is the center position of the work 19 because the work has a circular cross section. First, the center position of the reference block 21 is measured, and a mathematical formula of a circle representing the reference block 21 on the XY plane is stored in the storage unit 51 together with the known dimensions of the reference block 21. In the case where the reference block 21 is a prism or V block arranged in a valley shape, a straight line expression that represents a surface that abuts the side surface of the work 19 on the XY plane is stored. The shape and position of the reference plane may be stored as mathematical formulas as described above, or may be stored in the form of a data table that defines the reference plane. Further, the position of the contact portion 37 of the probe 33 is measured and stored in the storage means 51 together with the output value of the displacement sensor 39 at that time. Then, the work 19 is pressed against the work mounting surface 17 of the scale 15 and brought into contact with the reference block 21, and the work 19 is fixed to the scale 15 by the fixing means 23.

  Next, the actuator 33 moves the probe 33 closer to the workpiece 19, and outputs the measured value of the displacement sensor 39 when the contact portion 37 contacts the side surface of the workpiece 19 to the computing means 53. The calculation means 53 receives the data of the shape and position of the reference block 21 and the data of the position of the contact portion 37 of the measuring element 33 from the storage means 51, and formulas of two circles representing the reference surface in contact with the work 19 and the side surface of the work The center position of the work 19 can be obtained from the position data of one point. The origin setting means 55 sets the work coordinate system so that the obtained center position is the origin. In the present embodiment, the storage means 51, the calculation means 53, and the origin setting means 55 are incorporated in the numerical control device 57, and the numerical control device 57 performs the numerical control machine tool 1 so as to machine the workpiece 19 according to a given machining program. To control. The storage unit 51 and the calculation unit 53 may be incorporated in another device such as a machine control device or a personal computer, and send the obtained center position of the workpiece 19 to the origin setting unit 55 of the numerical control device 57.

  A second embodiment will be described with reference to FIG. As a reference block, a V block 61 having an opening angle of 90 ° is provided on the scale 15 with the opening angle facing upward, and a master piece 63 is placed on the V block 61 and fixed. The master piece 63 of this embodiment has a known dimension and a circular cross section. The contact portion 37 of the measuring element 33 is brought into contact with the side surface of the master piece 63, the point B on the side surface of the master piece 63 is measured, and the measured value is stored in the storage means 51. Further, since the shape and position of the V block 61, that is, the opening angle is 90 °, the mathematical formula of the straight line on the XY plane of the two inclined surfaces is known, and the dimensions of the master piece 63 are known, the machining is performed. With respect to the difference D between the measured value of the point C on the side surface of the workpiece 19 and the stored measured value of the master piece 63 by the probe 33 when the work 19 is placed and fixed on the V block 61, the master piece 63 The relationship between the center position E and the center position F of the workpiece 19 is input to the computing means 53 as a function in advance. If the side surface of the workpiece 19 is measured, the calculation means 53 can determine the center position F of the workpiece 19 with respect to the scale 15 from the function and the position data of one point on the side surface of the workpiece. The obtained center position F of the workpiece 19 is set as the origin of the workpiece coordinate system by the origin setting means 55, and the workpiece 19 is machined by a given machining program.

  FIG. 4 shows a case where a prismatic workpiece 71 having a square shape in the XY plane is attached to the workpiece fixture 13 instead of the circular workpiece 19. Also in this case, the position measuring unit 31 measures the position of the vertex G of the work 71 on the XY plane, and the vertex is calculated from the two straight line expressions representing the reference planes of the two prismatic reference blocks 73 stored in the storage unit 51. The calculation means 53 obtains the midpoint between the intersection point G of G and the two straight lines, that is, the position of the intersection point I of the square diagonal line on the XY plane of the work 71. This position may be set as the origin of the workpiece coordinate system as a reference for machining the workpiece 71.

  As described above, according to the present invention, every time a workpiece is mounted on the workpiece mounting base, a measuring means such as a touch probe is attached to or detached from the spindle of the numerically controlled machine tool, or the table is moved in the X, Y, and θ directions for alignment. The origin of the work coordinate system can be set in a short time.

  In the above-described embodiments, a case has been described in which a workpiece attachment having a vertical workpiece attachment surface is provided on a horizontal machining center. However, the present invention is not limited to this configuration, and a vertical machining center or other numerical control is provided. A machine tool having a horizontal workpiece mounting surface on a machine tool, for example, a horizontal V block and a position measuring means are provided on a horizontal pallet upper surface, and the workpiece is fixed to the pallet upper surface while being in contact with the reference surface of the V block. Including other configurations.

It is a front view which shows 1st Embodiment of the workpiece fixture of this invention. It is the side view and block diagram of a numerical control machine tool provided with the workpiece fixture of FIG. It is a front view of the principal part which shows 2nd Embodiment of the workpiece attachment tool of this invention. It is a front view when a prismatic workpiece is attached to the workpiece fixture of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Numerically controlled machine tool 13 Work fixture 15 Escale 19 Work 21 Reference block 23 Fixing means 31 Position measuring means 33 Measuring element 35 Actuator 39 Displacement sensor 51 Storage means 53 Calculation means 55 Origin setting means 57 Numerical control device

Claims (1)

In a workpiece machining method of a numerically controlled machine tool for machining a workpiece by relatively moving a tool mounted on a spindle and a workpiece mounted on a workpiece mounting base,
A reference block for contacting the workpiece is provided on the workpiece mounting base,
A position measuring means for measuring a side surface of the workpiece that is in contact with the reference block is provided on the workpiece mounting base,
Pre-store the shape and position of the reference surface with which the workpiece of the reference block contacts,
A master piece having a known size is brought into contact with a reference surface of the reference block and attached to the work mounting base, a measuring piece of the position measuring means is brought into contact with a side surface of the master piece, the master piece is measured, and the measured value Is stored in advance,
The work is brought into contact with the reference surface of the reference block and attached to the work mounting base, and the work piece of the position measuring means is brought into contact with the side surface of the work to measure the work,
Obtaining the position of the workpiece relative to the workpiece mounting base from the relationship between the center position of the workpiece and the measurement value of the stored master piece and the measurement value of the workpiece, and the center position of the predetermined master piece with respect to the difference between the two measurement values ,
A workpiece machining method for machining the workpiece by setting an origin of a workpiece coordinate system based on the obtained workpiece position.

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