JPS6110702A - Automatic work measuring apparatus - Google Patents

Abstract

PURPOSE:To make the chance of occurrence of errors, few, in an NC machine tool, by contacting a probe, which is mounted on a main spindle, to a material to be machined on the table of the machine tool after the finish of machining at a medium speed, returning the probe once after the measurement, contacting the probe again at a very slow speed, and performing the measurement. CONSTITUTION:The shape of a work 20 after the finish of cutting is to be measured on a table 2 of an NC machine tool. A cross rail 4 is mounted on a column (not shown), which is freely moved in the direction of the X axis. A saddle 15 is mounted on the rail 4 so that the saddle can be moved freely in the direction of the Y axis. A probe 10 is attached to a main spindle 17 of a ram head 16, which is mounted on the saddle 15 so that the head can be moved freely in the direction of the Z axis. An ON signal when the probe 10 is contacted to the work 20 is transmitted to an NC device 43 through a receiver 40 and a machine control board 41. The error between the signal and a reference value is outputted to an output printer 47. At this time, at first, the probe 10 is contacted to the work 20 at a medium speed, and the coarse measurement is performed. The probe is returned once, and it is contacted again at a very slow speed and the measurement is performed. Thus the error between the present position and the mechanical position of the NC apparatus can be made few.

Description

Detailed Description of the Invention (a) Technical field: Mounting a workpiece on a machine tool table without removing the workpiece from the table after cutting is completed.
The present invention relates to a method of measuring a workpiece by attaching a measuring stylus to a machine tool spindle and repeating a cycle of sequentially bringing the measuring stylus into contact with a plurality of pre-programmed specific points.

(B) Conventional technology After the cutting of the workpiece is completed, in order to precisely measure the shape of the workpiece (hereinafter referred to as the object to be measured), the object to be measured is removed from the machine tool table and transferred to the measurement table. This has drawbacks such as measurement errors due to removal, reading errors due to the use of a meter, and long measurement times.

(c) Purpose of the Invention The shape of a completed workpiece mounted on a machine tool table is measured by attaching a probe to the tip of the machine tool spindle, and using the main program of the NC device of the machine tool to measure the target value of the workpiece. By simply commanding P65 P13001 The purpose is to compare, output the error to a printer, repeat this cycle, and obtain the shape error of the object to be measured.

(D) Structure of the Invention The structure of the present invention is such that a measuring point is attached to the tip of the main spindle of a machine tool, and the object to be measured mounted on the machine tool table is measured while the measuring point is brought into contact with the object to be measured. in,
Examples thereof will be described below.

(e) Description of examples FIG. 1 shows a front view of a machine tool in which this method was implemented.

A table 2 is placed on the bed 1 and an X-axis servo motor 6
The columns 3, which are inverted and protrude from both sides of the bed, are connected and fixed so that the upper part is closed by the top beam 5, and a cross rail 4 is installed between both columns, and both columns are mounted movably. Attach the cross rail 4 to any position on the column using the screw 12 attached to the column.
can be positioned. In addition, a saddle 1 is mounted on the cross rail 4 so that it can be moved left and right by a Y-axis servo motor 7.
A ram head 16 is mounted on the saddle 15 and is driven by a Z-axis servo motor 8 so as to be movable up and down. Furthermore, on the right side of the front view, a tool magazine 12 for storing tools, measuring points, etc. is provided, and at the right end of the cross rail 4, a tool changing device 11 is provided for exchanging the tools and measuring points to the main shaft 17 of the ram head. There is.

Figure 1 shows a workpiece 20 placed on a table, and a workpiece 20 that has been completely cut by a command from a numerical control device (not shown).
0 shows the state in which the probe 10 attached to the main shaft 17 is attached. The system configuration is shown in Figure 2. The workpiece 20 (hereinafter referred to as the object to be measured) that has been placed on the table 2 and has been subjected to force machining is placed on the tip of the main shaft 17 of the ram head 16 by the tool changer 11, and the gauge head 10 is placed on the tip of the main shaft 17 of the ram head 16.
0 has a stylus attached to its tip, and when it comes into contact with the object to be measured 20 and is displaced, the contacts inside the probe operate, and when the operating signal is input to the skip terminal of the NC device 43, its current position data is displayed. This is a structure in which X, Y are stored in the register of the NC device.

The contact point 10 is brought into contact with the object to be measured 20 according to a program command by the Z-axis servo motor, and the contact-on signal is transmitted from the receiver 40 (using an optical signal not shown) to the machine control panel 41 and sent to the NC device 43. The reference value and the measured value are compared, and the error is outputted as data 4 by the printer 47.
It is formed by a system that prints out 8.

(f) Means to solve the problem This automatic workpiece measuring device uses the NC device of the machine tool, and the main program is G65P8001X-Y-Z-
3 and 4, a method for making a measurement by simply instructing Dd; by using a custom macro of the NC device function to bring the reference coordinate value and measuring tip into contact with the object to be measured will be explained.

After machining is completed, measurement head 1 is placed on spindle 17 by automatic measurement start.
2, set the measurement coordinate system, and position the probe 10 at the measurement origin a of the object to be measured. At this time, Dd specifies the final traveling direction during measurement, and the specification method is: Direction Specification Direction Specification Direction Specification +X D+1. +Y D+2 -Z D-3
-X D-1-Y D-2 is as shown in the table above, so the five Ds of ±X, 10Y, and -Z
By determining the value, three-dimensional measurement can be performed without commanding the measurement path. The D value is determined, the temporary measurement point position is calculated, the measurement point is moved to the temporary measurement position by fast forwarding, and the measurement cycle is performed. The measurement cycle is l)-+C- in Figure 3.
+ d - + e - + f. However, generally, simply touching the probe 10 to the object to be measured 20 and measuring based on the contact signal will include a measurement error, so the next measurement operation is performed.

The details of part a in Fig. 3 are shown in Fig. 5. From point b, the skip function is used to start rough measurement at a medium feed speed, and when the probe 10 comes into contact with the object to be measured 20 at point C. , a skip signal is sent to the NC device, but at this time the NC device memorizes its current position (however, this value deviates from the machine position by the amount of stagnation in the servo system, which is one of the major factors in measurement error, and this Since the amount of deviation is proportional to the feed speed, once the measuring stylus 10 is brought into contact with the object to be measured 20, as shown in Fig. 5, the same measuring point is measured again at a slow speed, so the current position of the NC device and the machine position are The error will be small. Contact the object 20 to be measured at very low speed, read the measured value, correct the measurement error, calculate the measurement error, print out the data 48, measure any point, and complete one cycle. Completed, but this cycle can be executed at multiple arbitrary points P specified by the main program.
, , P2 . . . , Pn are repeatedly measured to measure the shape error.

Next, in addition to the amount of accumulated pulses in the servo system mentioned above, measurement errors are affected by variations in the skip signal, delay in the sequence, dead zone of the probe 20, etc., so in order to correct these measurement errors, the machine tool On the table, shape dimensions (x, y
, z), which has already been measured, is measured using the program and measurement method described above, and the printed data 48 becomes the correction value, so this data is corrected by x, y, and z. Y axis of NC device as value,
It is stored in the Y-axis and Z-axis registers, and after reading the measurement coordinates ZM in the flowchart of FIG. 4, it is subtracted from the value of the current position stored as the measurement error correction Zm+ε, thereby improving measurement accuracy.

(g) Effects of the invention By using this method, the object to be measured conventionally had to be removed from the machine tool table and measured with a measuring instrument, but it is now possible to use the NC device of the machine tool. By simply attaching the machining completed layer to the main spindle on the machine tool table, when the workpiece is machined using the program commands of the NC device, the measurement program is commanded in the same coordinate system, and the measurement target is measured using the main program. Measurement can be carried out simply by commanding the reference coordinate values of the object, and the printout does not require any skill, and the printout of measurement errors makes it easy to check program errors and tool wear conditions.

In addition, by specifying D value discrimination in the program, it is possible to specify the measurement direction during measurement without commanding the measurement path, allowing three-dimensional measurement, and the stylus of the measuring point contacts the object to be measured at medium and slow speeds. By doing so, it was possible to reduce the variation in the amount of stagnation in the servo system and the amount of deviation, thereby achieving an improvement in measurement accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a machine tool according to an embodiment, and FIG. 2 is a system configuration diagram of an automatic workpiece measuring device. FIG. 3 shows the measurement operation by the probe, and FIG. 5 shows the details of the measurement cycle. FIG. 4 shows a flowchart of automatic measurement. bed, 2: table, 6: X-axis servo motor, 7:
X-axis servo motor, 8: Z-axis servo motor, 9: Spindle motor, 11: Tool changer, 16: Spindle head, 12:
Tool storage magazine, 15: Saddle, 17: Spindle, 40 receiver, 41: Machine control panel, 43: NC device, 47
:Output printer, 48:Data

Claims (1)

[Claims] 1. In an NC machine tool, after completing machining of a workpiece placed on the machine table, a probe is attached to the spindle, and the function of the NC device is used to machine the workpiece. Regarding the method of measuring the shape after completion (hereinafter referred to as the object to be measured), when bringing the measuring point into contact with the object to be measured, the measuring point is brought into contact with the object to be measured at medium speed, then returned once, and then returned to the same measuring point again at slow speed. A measuring method characterized by contacting and measuring. 2. A measurement method characterized in that a measurement path is specified by instructing a program to determine a measurement direction using the method according to claim 1. 3. Place the model having the reference value determined in advance in claim 1 on the machine tool table;
Measure the model for each axis with a measuring stylus using the measurement method described above,
A measuring method characterized in that the difference between a reference value and a measured value is stored in a register of an NC device as a correction value for each axis, and is used for correcting the measurement of an object to be measured.