JPH10138096A - Measuring device for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine tool measuring device in which measuring precision can be improved, and in which structure is simple to reduce the number of components to achieve a low cost. SOLUTION: A device comprises such a structure that a base end side of a sensor arm 11a is rotated by combination of a rack 20 connected to a close coupled type hydraulic cylinder 21 and a pinion 19 engaged with it to position a touch sensor 10 on the main shaft side for measuring, and on the counter-main shaft side for stand-by, where the sensor arm 11a is stopped rotation by a stopper 27 to set the sensor 10 and the sensor arm 11a in measurement conditions. A spring 24 is provided between an actuator and the rack 20 to let output of the hydraulic cylinder 21 escape when rack pressure by the hydraulic cylinder 21 gets to exceed a specified value after rotation of the sensor arm 11a is stopped by the stopper 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for a machine tool, and more particularly to a measuring device for measuring a workpiece set near a spindle head.

[0002]

2. Description of the Related Art Conventionally, as a measuring device for a machine tool of this type, for example, one described in Japanese Utility Model Laid-Open Publication No. 7-17457 is known. The schematic configuration of the measuring device described in the above publication includes a turning arm (second arm) that is provided near the spindle head and is provided so that the base end can turn vertically.
It comprises a hydraulic cylinder for turning the turning arm, a slide arm (first arm) provided to be able to advance and retreat in parallel with the turning arm, and a measuring instrument attached to the tip of the slide arm. In this measuring device, the turning arm is turned to a measuring position (substantially horizontal state) away from the spindle head by the hydraulic cylinder, then the slide arm is extended forward, and the measuring device of the slide arm is brought into contact with the work. A measurement is taken. When the measurement is completed,
The slide arm is retracted, and the pivot arm is pivoted to a retracted position (substantially vertical state) close to the spindle head.

[0003]

However, the above-mentioned conventional measuring apparatus for machine tools has the following problems. When the swing arm is swiveled by the hydraulic cylinder for measurement, the swing arm is stopped at the measurement position because the locking step provided at the base end of the swing arm abuts against the stopper on the frame side. In other words, the structure is such that the force generated by the hydraulic cylinder directly acts on the stopper.
For this reason, if the hydraulic pressure supplied to the hydraulic cylinder fluctuates due to the pulsation of the hydraulic pump or the start / stop of other hydraulic equipment, the pressing force acting on the stopper fluctuates. The amount of deformation of the structure including the stopper also varies. Therefore, the position of the measuring device cannot be kept constant, and a large measurement error occurs. When the measuring device is in the measuring position, the structure for supporting the measuring device with respect to the spindle head is not rotationally symmetric with respect to the axial direction of the measuring device. For this reason, thermal deformation does not occur uniformly in the axial direction of the measuring instrument, but causes bending or warping, and the position of the measuring instrument cannot be kept constant. For this reason, a large measurement error occurs. In particular, this measurement error appears remarkably when the ambient temperature fluctuates. A movable mechanism for both the revolving part and the sliding part is provided. For this reason, the number of gap elements in the movable part increases, for example, as compared with a structure having only one of the parts, and high-precision measurement cannot be performed structurally.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to improve the accuracy of measurement, and to reduce the cost by simplifying the structure and reducing the number of parts. An object of the present invention is to provide a measuring device for a machine.

[0005]

According to the first aspect of the present invention, a measuring instrument disposed near a spindle head of a machine tool is supported by a measuring instrument supporting portion, and the measuring instrument is retracted to the spindle side during measurement. Sometimes, the base end side of the measuring device supporting portion is turned by a combination of a rack connected to a direct-acting actuator and a pinion meshed with the rack, so as to be positioned on the side opposite to the main shaft,
A measuring device for a machine tool which is positioned so that the measuring instrument support is turned into a measurement state by stopping the turning of the measuring instrument support by a stopper, wherein the measuring instrument support is positioned between the actuator and the rack. When the rack is moved by the actuator and the measuring instrument support is turned to the measurement state side, and when the measuring instrument support is stopped from turning by the stopper, the rack pressing force by the actuator attempts to exceed a certain value. A rack pressing force adjusting means for releasing the output of the actuator and keeping the rack pressing force within a certain value is interposed. The invention according to claim 2 is characterized in that the rack pressing force adjusting means is constituted by a spring. According to a third aspect of the present invention, the measuring device support is configured to be rotationally symmetric about the measuring device.

[0006]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic plan view of a machine tool provided with a measuring device according to the present invention, wherein reference numeral 1 denotes a spindle on which a tool T is mounted, and 2 denotes a spindle head. The touch sensor 10 is supported by the measuring instrument support 11 near the spindle head 2, specifically, on the side of the spindle.

The support structure of the touch sensor 10 will be described in detail. As shown in FIG. 3, a bracket 13 is mounted on the head body 12, and left and right bearings 15 and 15 are mounted on a support body 14 mounted on the bracket 13.
A shaft 16 is rotatably supported via 15. Axis 1
The measuring instrument support 11 is attached to an end protruding outward from one of the bearings 15 by a fastener 17 so that the measuring instrument support 11 rotates integrally with the shaft 16. . In this embodiment, an example in which the sensor arm 11a is used as the measuring device support portion 11 is shown.
The sensor arm 11a is rotationally symmetric with respect to the axial center of the touch sensor 10 (measuring device) attached to the tip.

A pinion 19 is keyed at an intermediate position between the portions of the shaft 16 supported by the bearings 15, 15.
It is mounted so as to rotate integrally with the shaft 16. The pinion 19 is, as shown in FIG.
Guide groove 14 of the support body 14 attached to
a is engaged with the rack 20 which is guided to be able to move up and down. The rack 20 is moved up and down by a hydraulic cylinder 21 supported by a holder attached to the support body 14.

A rod 21a extending from the hydraulic cylinder 21
, A shaft 22 is coaxially mounted via a coupling 23. The shaft 22 has a distal end inserted into a vertical groove 20 a formed in the rack 20. A spring 24 is interposed between the large diameter portion 22a at the tip of the shaft 22 and the spring retainer 18 attached to the upper end of the vertical groove 20a of the rack 20. When the shaft 22 is lowered by the hydraulic cylinder 21, the bottom of the vertical groove 20 a is pushed by the large-diameter portion 22 a at the tip of the shaft 22, so that the rack 20
When the shaft 22 is raised by the hydraulic cylinder 21 and the lower surface of the spring retainer 18 is pressed via the spring 24, the rack 20 is raised.

Here, the elasticity of the spring 24 is smaller than the attractive force when the hydraulic cylinder 21 retracts the rod.
The touch sensor 10 is set so as not to move with respect to a load when the touch sensor 10 comes into contact with the workpiece W and measures.

As shown in FIG. 3, a stopper arm 25 is attached to the shaft 16 so as to rotate integrally with the shaft 16 via a key (not shown) so as to straddle the pinion 19. An adjustment bolt 2 is provided on the side of the stopper arm 25.
6, a stopper 27 is attached to the upper surface of the stay 14a extending from the support body 14, and when the stopper arm 25 is integrally rotated with the shaft 16 in the counterclockwise direction in FIG. The rotation position of the stopper arm 25 and the shaft 16 that rotates integrally with the stopper arm 25 are determined by the adjustment bolt 26 of 25 being pressed against the stopper 27. 2 and 3, reference numeral 30 denotes a sensor cover,
This protects the touch sensor 10 in the standby state.

Next, the operation of the measuring device for a machine tool having the above configuration will be described. 2 and 3 show the touch sensor 10.
Indicates a state where is in the standby position. At the point of time when the preliminary processing by the tool T has been completed, the touch sensor 10 measures whether or not the desired processing has been performed.

More specifically, the measurement is performed by driving the hydraulic cylinder 21 to retract the rod 21a. At this time, the large-diameter portion 22a at the tip of the shaft 22 also rises integrally, and the lower surface of the spring retainer 18 is pushed via the spring 24, whereby the rack 20 rises. Accordingly, the pinion 19 pivots counterclockwise in FIG. 2, and the shaft 16, the stopper arm 25, and the sensor arm 11a are integrally formed with the pinion 19.
Turns in the same direction.

When the adjustment bolt 26 of the stopper arm 25 is pressed against the stopper 27 on the stay 14a, the rotation of the stopper arm 25 and the shaft 16 is stopped.
At this time, the rotation of the sensor arm 11a attached so as to rotate integrally with the shaft 16 is also stopped, and as a result, the sensor arm 11a is parallel to the rotation axis of the main shaft 1 as shown by a two-dot chain line in FIG. And eventually becomes a measurable state.

Here, the shaft 16 and the sensor arm 1
1a and the like are turned by the attractive force of the hydraulic cylinder 21a as described above, but the pressing force when the adjusting bolt 26 attached to the stopper arm 25 presses the stopper 27 varies the hydraulic pressure supplied to the hydraulic cylinder 21. The amount of deformation of the structures such as the stopper arm 25 and the support body 14 increases and decreases due to the change in the pressing force of the adjustment bolt 26 against the stopper 27, and as a result,
It is feared that the stop position of the sensor arm 11a changes due to the fluctuation of the hydraulic pressure to the hydraulic cylinder 21 and a large measurement error occurs. However, since the spring 24 is interposed between the hydraulic cylinder 21 and the rack 20, the hydraulic cylinder 2
1 exceeds the predetermined value, the hydraulic cylinder 21
Does not directly contribute to the pressing force of the stopper 27, but the spring 24 contracts to absorb the output of the hydraulic cylinder 21 that is equal to or greater than a predetermined value. That is, the spring 2 which is held substantially constant
With the pressing force of 4, the turning position of the sensor arm 11a is determined. As a result, the measurement device supporting rigidity system (shaft 1) caused by the pressure fluctuation of the hydraulic pressure supplied to the hydraulic cylinder 21
6, bearing 15, stopper arm 25, stopper 2
7, the displacement of the stay 14a and the support body 14) is released, and the measurement position of the touch sensor 10 is kept constant, so that highly accurate measurement can be realized.

In addition, since the sensor arm 11a which is rotationally symmetric about the touch sensor 10 is used as a member for supporting the touch sensor 10, for example,
Even if the ambient temperature fluctuates, the thermal deformation generated in the sensor arm 11a only occurs in the axial direction, and no bending or warpage occurs, and as a result, the measurement accuracy is improved.

Note that even after the rotation of the sensor arm 11a is stopped by the action of the stopper 27, the operation of retracting the rod 21a upward by the hydraulic cylinder 21 is continued. Is held. When the above measurement is completed, the hydraulic cylinder 21 extends, and the lower surface of the large diameter portion of the shaft 22 is
The rack 20 is lowered by pressing the bottom of the pinion a.
9 rotates clockwise in FIG. 2, and as shown by a solid line in FIG.
0 reaches the standby position.

<Other Application Examples of the Present Invention> The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. In the above-described embodiment, the hydraulic cylinder 21 is used as an example of the actuator. However, other actuators such as an air cylinder may be used. Further, in the above-described embodiment, the touch sensor 10 is used as the measuring device, but the type of the touch sensor does not matter.

[0019]

As described above, according to the apparatus for measuring a machine tool according to the first aspect, the rack which releases the output of the actuator and maintains the rack pressing force within a certain value is provided between the actuator and the rack. Since the pressing force adjusting means is interposed, even if the fluid pressure supplied to the actuator fluctuates, the amount of deformation of the measuring device support system when stopped by the stopper does not fluctuate, and consequently the position of the measuring device Can be kept constant to improve the measurement accuracy. In addition, since only the turning portion is sufficient for the driving portion, the configuration is extremely simple, cost reduction can be achieved, and high-precision measurement can be performed. According to the measuring device for a machine tool according to the second aspect, since a spring that is relatively inexpensive and easy to control in quality is used as the rack pressing force adjusting means, the production cost can be reduced, and the measurement cost can be reduced. The position of the measuring instrument can be easily positioned with high accuracy. According to the measuring device for a machine tool according to the third aspect, since the measuring device support portion is configured to be rotationally symmetric about the measuring device, the measuring device support portion is bent or warped even when the ambient temperature fluctuates. Or measurement error can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a main part of a machine tool provided with a measuring device according to the present invention.

FIG. 2 is a side sectional view showing a measuring device of the machine tool.

FIG. 3 is a partially sectional view taken in the direction of arrow X in FIG. 2;

[Explanation of symbols]

1 spindle, 2 spindle head, 10 touch sensor (measuring device), 11 measuring device support, 11a sensor arm,
12 head body, 16 axes, 19 pinion, 20
Rack, 21 hydraulic cylinder (actuator), 24
Spring, 25 stopper arm, 27 stopper,
T tool, W work.

Claims (3)

[Claims] A measuring instrument (10) arranged in the vicinity of a spindle head (2) of a machine tool is supported by a measuring instrument supporting portion (11), and the measuring instrument is on a main spindle side during measurement and a counter-spindle when retracted. The base end side of the measuring device support is pivoted by a combination of a rack (20) connected to a linear actuator (21) and a pinion (19) meshed with the rack so as to be positioned on each side. A measuring device for a machine tool, wherein the measuring device support is stopped from turning by a stopper (27) and the measuring device support is positioned so as to be in a measurement state; When the rack was moved by the actuator between the rack and the measuring instrument support to pivot toward the measurement state, the measuring instrument support was stopped from turning by the stopper. A rack pressing force adjusting means (24) for releasing the output of the actuator and keeping the rack pressing force within the fixed value when the rack pressing force by the rear actuator exceeds a certain value is interposed. Measurement equipment for machine tools. 2. The machine tool measuring device according to claim 1, wherein said rack pressing force adjusting means comprises a spring. 3. The measuring device for a machine tool according to claim 2, wherein the measuring device support portion is configured to be rotationally symmetric about the measuring device.