JPS6161745A - Work-uncentering compensator - Google Patents

Abstract

PURPOSE:To compensate a form error in a probe as well as to calculate the centering of a work, by making the prove of a touch sensor come into contact with a four-point work per one-axis direction. CONSTITUTION:A touch sensor probe is moved on an X-axis, turning the probe itself at one side of a work W, and a mean value X1 of two-point contact at 0 deg. and 180 deg. is secured and likewise a mean value X2 at the opposite side is secured. That is, X1=(B1+B2).1/2...(1) X2+(A1+A2).1/2-...(2), and next, in order to measure a direction (a Y direction) orthogonal with a moving direction of the probe P measured in an X direction, the probe P is situated on the Y- axis, and with movement in the Y-axis direction, it is secured likewise Y1=(D1+D2).1/2...(3) Y2=(C1+C2).1/2...(4), therefore a distance from a reference position in the Y-axis direction to the work center is Lx=(X1+X2).1/2...(5), and likewise it comes Ly=(Y1+Y2).1/2, thus the work center positions Lx and Ly are found out of a machine zero position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides contact calculation methods for machine tools such as NC lathes and vertical machining centers. jtl+ device, particularly a workpiece misalignment correction device that approximates the center of a touch sensor probe and the center of a workpiece used in vertical machining centers that control the X, Y, and Z axes to obtain highly accurate measured values. .

Conventionally, measurement devices using touch sensors in machine tools such as NC lathes and machining centers have been configured to form electrically closed circuits and obtain signals through contact between the workpiece and the probe. is normal. That is, in a vertical machining center as shown in Fig. 1,
The machining work is carried out using a table T on which the workpiece W is placed and movable on a horizontal plane, a tool inserted into the end of the spindle H, a machining head Z attached to a column L so as to be movable up and down, and the workpiece W within the horizontal plane. It is performed with relative movements in two directions.

Tools attached to spindle H are magazines M to A.
It can be automatically replaced via a TC (not shown), and when measuring a workpiece, etc., the touch sensor TS can be called out from the magazine M and attached.

FIG. 2(A) is a plan view showing an example of a measurement method using a conventional device. In the same figure, the spindle center axis 11
The outer circumferential surface of the workpiece W is brought into contact with the probe P of the touch sensor TS and measured by the movement in the X and Y directions passing through the workpiece W. At this time, the spindle center axis 11 and the center of the probe P are not necessarily aligned. Further, the spindle center axis 11 does not necessarily coincide with the center 12 of the workpiece. If the contact surface S-8 between the outer circumferential surface of the workpiece and the probe P attached to the spindle end perpendicular to the plane of the paper is always orthogonal to the axis 22 of the measurement operation of the touch sensor TS, then the contact surface S-8 is perpendicular to the workpiece W. Centering can be performed by bringing the probe into contact with the probe from both directions of the two axes, that is, from four directions, measuring each coordinate value, and calculating the average value. However, as shown in FIG. 2(b), if there is a case where the tangent surface s-s' is not necessarily perpendicular to the axis 22 of the measurement operation, the calculation of the average value will not be centered. In other words, the moving axis 22 of the probe of the touch sensor does not necessarily pass through the center of the workpiece, and the shape of the probe is not necessarily completely concentric spherical. Also, the center of the probe does not coincide with the central axis of the main spindle, making measurement using conventional equipment difficult. However, when centering the hole or boss of the workpiece, a measurement error occurs and a highly accurate measurement value cannot be obtained.

The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the axial force of the probe when centering a hole or boss of a workpiece, even if the axial force of the probe does not coincide with the center of the hole or boss. It is an object of the present invention to provide a workpiece misalignment correction device that can obtain a high-N degree measurement value with little measurement error even if any of them do not match.

To achieve this objective, the present invention provides a central control means 1
, a workpiece centering measuring means 2, a calculating means 3 for calculating the average value of the measured values by the measuring means 2,
A reversing positioning device 4 that performs 80° positioning, an input device 5 that inputs data such as machining position, and a motor control device 6 that positions the machining head relative to the workpiece.
Two orthogonal axes are set near the intersection of the X and Y directions that pass through the spindle center axis using a correction device equipped with a One probe for each direction of the measurement operation.
Rotate 80 degrees, take each measurement, move the probe in the opposite direction, and repeat the same operation, making a total of 4 measurements per axis.
The feature is that the average value is calculated from the measurement results.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a plan view showing a measuring operation of a touch sensor in an example of a workpiece misalignment measuring method using the apparatus of the present invention. In the same figure (a), since the spindle center axis 22X is not necessarily aligned with the center 12 of the workpiece W itself, centering measurement is first performed in order to apply the machining data.

However, it is assumed that the axes of the measuring operation of the touch sensor 2 to be measured, that is, the central axes 22X and 22y of the spindle, are also offset from the workpiece center 12, and high accuracy of measurement is intended. The principle of the present invention is to set two orthogonal axes x-x' and Y-Y' near the center of the workpiece, and to move the touch sensor 2 for measurement in parallel and bidirectionally along these two axes. Bye.

Now, as shown in the embodiment of the present invention, a measurement procedure will be described when measuring the misalignment of a workpiece in a vertical machining center by controlling the X, Y, and Z axes of the main axis into which the probe P is inserted. First, as shown in Figure 3 (a), move the probe on the X-axis to measure the diameter of the workpiece, rotate the probe itself on one side of the workpiece, and make two-point contact at 0° and 180°. Obtain the average value x 1, and similarly calculate the average value x on the opposite side of the workpiece.
Get 2.

That is, for measurement when the workpiece center 12 is located on the X-minus side with respect to the central axis of the spindle, the probe is brought into contact with it from the minus side, and then the probe itself is
Rotate 6 times and measure twice, measured values B1 and B2
get. Next, the probe is moved to the opposite X-plus side, and the measurement is repeated to obtain measured values A1 and A2.

That is, the average value of each is: X+ = (B+ "Bz) ・1/2...
...(1)X2 = <A, ÷A2)・1/
2......(2).

Next, in order to measure in the direction (Y direction) perpendicular to the moving direction of the probe P that has been measured in the X direction, the probe P is positioned on the Y axis, and the workpiece diameter is Measurements will be made. That is, as shown in FIG. 3 (0), the probe P;f: is brought into contact with the workpiece W from the Y plus side and measured twice, and then moved from the Y plus side to the Y minus direction. Therefore, the measured values C3 and C2
, and by moving in the opposite direction, the measured values 1 and 2 are obtained.

That is, each average value is Yl = (Dl + D2)・1/2...
(3) y2= (c, +C2) ・1/2...
...(4).

Next, the workpiece centering calculation will be explained according to FIG.

As shown in Fig. 4 (A), each contact point X, , X2 of the workpiece is obtained from the reference position GX, which is the origin in the X-axis direction, and the distance LX to the center of the workpiece is 2 (1), (2+).
LX = (XI +Xz)
・ 1/2 ・・・・・・・・・(5) Immediately,
Lx = (+t1+3. +Az+Bz) ・
1/4 ...(6) is obtained.

Similarly, as shown in Figure 4 (+1),
From the axial origin reference position GY to each contact point of the workpiece Y13Y
2 is obtained, and the distance L7 to the center of the workpiece is expressed by equation (3).

From (4), Lv = (Yl + Yz) ・1/2...
...(7) Ly = (CI+D+ +z+Dz)
・1/4・・・・・・(8)

The workpiece center position can be obtained from equations (6) and +8), and LX
.

Lv is the absolute value of the distance from the machine origin (absolute)
Expressed as

As described above, the centering deviation measurement using the device of the present invention is performed by contacting four points in the l-axis direction. That is, by rotating the probe P itself and turning it 180 degrees, A+, Az
, B+, and B2 are obtained in order to correct the shape error of the probe. Then, centering involves moving the probe to the facing side and measuring from both directions.

Here, a schematic configuration diagram showing an example of the coordinate system correction (work center deviation measurement) device of the present invention will be explained with reference to FIG. In the same figure, the coordinate system correction device for the machining position is the central control procedure (
(hereinafter referred to as CPU) L, workpiece centering measurement means 2, calculation means 3, and main axis measurement probe P are controlled at 0 degrees and 180 degrees.
111, and further includes a positioning means 4 for the main shaft MS, and a cp
Connected to the main lot 41 from the UL are an information manual means 5 for inputting data such as machining positions, and a morph control I means 6 for performing measurement correction and machining positioning for the workpiece W.

First, to find the center of the workpiece on the X-axis side, use a command from the CPU to move the touch sensor T5 to the
By moving the axis relative to the table T, it hits the outer periphery of the workpiece W on the B side. At this time, the distance from the reference position to the position where the signal from the touch sensor T5 is generated is taken in as position data α1. The position data α1 of B1 is input to the F2AM31 via the A N D gate as a first measurement signal.

Then, the main shaft is rotated 180 degrees by the main shaft motor M5, and the main shaft is applied to the outer periphery of the workpiece WOB side.

At this time, the distance from the reference position to the position where the signal of the touch sensor T is generated is taken in as position data α2,
The position data α2 of B2 is AN as the second constant signal.
The position data α2 of B2 is entered into the RAM 32 via the D gate.

Next, move the touch sensor T5 to the facing A side of the workpiece W, apply it to the outer circumference of A, and similarly transfer the data α3 of A1 to the RAM.
33.

Next, rotate the main axis 180 degrees, and in the same way, data α4 of A2
is taken into the RAM 34, the data in the RAMs 31 to 34 are calculated in the arithmetic circuit 35, and B8 is recorded in the correction memory in the CPU according to the X-axis correction command.

Next, the contents of RAM 31.32.33.34 are cleared, and as described above, C,, C, in the Y-axis direction.

Data β1 of DI and RI. B2. Input B3 and B4 in RAM 4.

In order to find the center on the Y-axis side, calculations are performed in the arithmetic circuit 35 according to instructions from the CPU, and according to the Y-axis correction command Q, β7 is sent to the CPU.
recorded in the internal correction memory.

The above-mentioned misalignment measurement is performed by moving the table along the main axis in the Z direction.
Although we have explained the mechanical configuration of a vertical manning center that uses x, y, and z-axis control to move the table in the It is not limited to mechanical configuration.

Furthermore, when measuring center misalignment in a vertical machining center whose configuration is x, y, z, and C-axis control,
It is as follows.

That is, the center of the workpiece is placed on a rotary table that is movable on the X-axis and is controlled along the C-axis, with the center of the workpiece aligned approximately on the central axis of rotation, and the misalignment is measured.

In this case, as mentioned above, the average value on the X axis.

After obtaining ×2, the table was rotated 180 degrees and the probe was rotated 180 degrees to the 0 degree position and measured.
Value Δ3. A4, B:I', B4 are obtained.

The average value of each is
)Xs = (B3"B4)/2......α
O), and the distance LX 18° from the origin Gx in the X-axis direction to the center of the workpiece at this time is L81uo-(XJ-I-X4)/2...
- Obtain (11).

Next, when determining the measured value in the Y-axis direction, the table is rotated 90 degrees on the X-axis using C-axis control, and the probe is placed at the 0 degree position, since the machine's table movement cannot be controlled by the Y-axis. Then, the probe is rotated 180 degrees and measured by touching one side of the workpiece, and then moved on the X axis to measure the opposite side of the workpiece.

At that time, the respective measured values C+, C2, Dl, and Dz were obtained and their average value was 2 (31, (from 41, Yl).

Y2 is calculated, and the distance LY9° from the origin Ox to the center of the workpiece in the X-axis direction is LYQ. = (Y, +Y2)/2・・・・・・・・・・
...(12).

Next, with the table turned 180 degrees from that position, measurements were taken on the opposite side of the workpiece (direct C3, C4).
,D:l+D, is obtained.

The average value of each is Y:l = ((,3+c< )/2...
・(13)Y4 = (Dff +D4)/2...
......(14), and at this time, the distance from the origin Ox to the center of the workpiece in the X-axis direction is L7□7°, 27° = (y3 + Y4)/2...
...(15).

Here, from the initial state, that is, the average value X before table rotation and the average value LX 100 after 1806 rotations, the origin G
The distance from X to the center of the daple in the X-axis direction is L = (LX + LX +110) / 2--
-----=-<16) is calculated. The distance β111M from the origin GX to the table center in the X-axis direction, which is replaced on the X-axis in the Y-axis direction, is similarly calculated from the average value LX'lG before the table turns and the average value LY□7o after the table turns 180 degrees. M= (LY 9G+Ly zzo) / 2--・
...(17) is obtained.

Next, when determining the center misalignment of the workpiece, when the table is returned to its original position,
direction, and deviation in the Y direction ■a.

b is a=L, I, X ・・・・・・・・・・・・(18
)b=M−La,.・・・・・・・・・・・・(19
). That is, centering measurement according to the present invention is determined by contacting eight points in one axis direction.

As explained above, according to the present invention, when centering a hole in a workpiece or a boss, even if the measurement axis of the touch sensor is not completely aligned with the center of the liquid hole or boss, high precision with small measurement errors can be achieved. It is possible to provide a workpiece misalignment correction device that obtains measured values, and this device exerts a valuable effect on the control unit 11 of machine tools such as NCj 12 m and drilling machines.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of a vertical machining center, Fig. 2 is a plan view of a conventional measurement method, and Fig. 3 is a measurement operation of a workpiece centering sensor in an example of the workpiece center deviation meter Jll method using the device of the present invention. FIG. 4 is a plan view showing a method for measuring workpiece misalignment according to the present invention, and FIG. 5 is a configuration diagram of a standard reference system correction device according to the present invention. 1... Workpiece 2... Workpiece centering measurement means 3
...Calculating means 4...Positioning means 5...
Input means 6...Motor control means 1 [...Spindle center axis 12...Workpiece center 21...Probe 22...
・Measurement axis patent applicant Hitachi Seiki Co., Ltd. Figure 2 (A) Figure 3-4

Claims (1)

[Claims] In a workpiece misalignment correction device for a machine tool that performs processing by relative movement between a workpiece held on a table and a tool on a spindle, the device includes a motor control means for relative movement to the table or the spindle for positioning; 0° or 18
A positioning means for positioning the spindle angle at two positions of 0°, a workpiece centering measuring means attached to the spindle and generating a contact signal with the workpiece during measurement, and an arbitrary spindle that crosses the workpiece for measuring the workpiece. A workpiece misalignment correction device comprising a calculation means for measuring at four positions on an axis and a motor control means at that time calculating an average value of the position data of the measured values.