JP7286512B2 - test indicator - Google Patents

Description

The present invention relates to test indicators.

Test indicators (so-called lever type dial gauges) are known (for example, Patent Documents 1 to 4). Test indicators are used for minute displacement measurements such as circumferential runout, total runout, flatness, and parallelism, as well as precision comparison inspections such as machining errors of a processed product against a masterwork (or block gauge).

The test indicator has a measurement arm rotatably supported on the body case, and the rotation of the measurement arm is magnified by the principle of leverage, and the displacement is transmitted by the gear train. Then, minute measured values are magnified and displayed by rotating the pointer at the final stage.

JP 2008-309687 A Japanese Patent No. 6447997 Japanese Utility Model Publication No. 61-017363 JP-A-53-140053

Since the conventional test indicator is a mechanism that transmits displacement using a lever or gear train, the accumulation of mechanical errors remains an unavoidable problem. Further, the rotation of the measuring arm is converted into the displacement amount d of the probe, and this conversion ratio is a value fixed by the lever ratio and gear ratio. Therefore, in order to change the length of the measuring arm according to the work, it was necessary to prepare a plurality of test indicators for measuring arms of different lengths.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a test indicator that minimizes accumulated mechanical errors and improves detection accuracy.

The test indicator of the present invention is
a measuring arm having a probe at one end;
a head section that pivotally supports the other end side of the measurement arm with an axis orthogonal to the axial direction of the measurement arm as a rotation axis;
a transmission shaft member inserted through the head portion so as to linearly advance and retreat in the head portion in conjunction with the rotation of the measurement arm;
a body housing portion that holds the head portion so as to rotate about the transmission shaft member;
a linear encoder that is provided in the body housing portion, has a movable body that linearly advances and retreats in conjunction with the advance and retreat of the transmission shaft member, and detects displacement of the movable body;
a displacement conversion unit that converts the displacement of the movable body into displacement in a direction perpendicular to the axial direction of the measurement arm of the probe;
a display unit for displaying the displacement of the stylus calculated by the displacement conversion unit.

In one embodiment of the invention,
The displacement conversion unit is provided with a measurement arm length storage unit for setting and storing the length of the measurement arm,
It is preferable that the displacement conversion section changes the conversion ratio according to the length of the measurement arm.

In one embodiment of the invention,
The linear encoder is preferably an absolute encoder.

1 is an external view of a first embodiment of a test indicator; FIG. Fig. 10 is a front view of the test indicator; FIG. 10 is a cross-sectional view of the test indicator; FIG. 4 is a diagram showing a cross-sectional view taken along line IV-IV in FIG. 3; 3 is a functional block diagram of an electrical component; FIG. It is the figure which illustrated a mode that a measurement arm displaces. FIG. 4 is a diagram illustrating how a test indicator measures a surface to be measured; It is a figure which illustrated a mode that there exists angle theta between a measurement arm and a to-be-measured surface.

(First embodiment)
FIG. 1 is an external view of a first embodiment of a test indicator 100 according to the invention.
This test indicator 100 is a so-called universal type test indicator 100, and as illustrated in circles 1A and 1B in FIG. that can be changed. The test indicator 100 of the first embodiment is a digital display type test indicator 100 that digitally displays the displacement (measured value) of the tracing stylus 240 on the display section 400 .
The configuration of the test indicator 100 of the present invention will be described below with reference to the drawings.

FIG. 2 is a front view of the test indicator 100. FIG. The test indicator 100 includes a head portion 200 , a body housing portion 300 and a display portion 400 .

The head portion 200 is attached to one end side of the body housing portion 300 . At this time, the head section 200 pivotally supports the measurement arm 230 so as to allow the rotation of the measurement arm 230, and the head section 200 itself is also attached so as to rotate with respect to the main body housing section 300. . As shown in FIG. 2, the head portion 200 has a pair of opposing pieces at one end thereof, with a predetermined gap between the two opposing pieces. These two opposing pieces on one end side of the head portion 200 are called outer frame opposing pieces 210 . An arm support shaft 220 is provided so as to pass through the two outer frame facing pieces 210 .

The measurement arm 230 has a probe 240 at one end, as shown in FIG. The other end side of the measuring arm 230 is U-shaped when viewed from the front side in FIG. 2 and has two opposed pieces. These two opposing pieces on the other end side of the measuring arm 230 are called inner frame opposing pieces 250 . The inner frame facing piece 250 is inserted inside the outer frame facing piece 210 and is pivotally supported by the arm support shaft 220 so as to be rotatable. This arm support shaft 220 is a shaft perpendicular to the axial direction of the measurement arm 230 .

FIG. 3 is a cross-sectional view of test indicator 100. As shown in FIG.
As shown in the cross-sectional view of FIG. 3, the head portion 200 has a through hole 260 penetrating from one end side to the other end side. A transmission shaft member 270 is provided in the through hole 260 so as to be slidable in the axial direction. One end of the transmission shaft member 270 is divided into two and has two legs 275 straddling the arm support shaft 220 . Also, the transmission shaft member 270 is always biased toward one end by a spring 261 .

The head portion 200 is attached to the body housing portion 300 so as to rotate around the transmission shaft member 270. As shown in FIG.

FIG. 4 is a diagram showing a sectional view taken along line IV-IV in FIG.
As shown in FIGS. 3 and 4 , a cam member 280 is provided between the measuring arm 230 and the transmission shaft member 270 to transmit the rotation of the measurement arm 230 to the transmission shaft member 270 .
The cam member 280 is a substantially semicircular flat plate, and is placed between the inner frame opposing pieces 250 of the measuring arm 230 and supported by the arm support shaft 220 . The cam member 280 has a substantially semicircular shape, but if the original perfect circle is hypothetically considered, it is supported by the arm support shaft 220 so that the center of this imaginary circle becomes the center of rotation.

A spherical or hemispherical contactor 281 is provided on a linear portion corresponding to the diameter (or chord) of the substantially semicircular cam member 280 . The contacts 281 are provided on both sides of the arm support shaft 220 (rotation center). As described above, two legs 275 are provided on one end side of the transmission shaft member 270 so as to straddle the arm support shaft 220 . An end of each leg 275 abuts on a contact 281 of the cam member 280 .

A disk spring 285 is interposed between the cam member 280 and one of the inner frame facing pieces 250 of the measuring arm 230, as shown in FIG. The disc spring 285 presses the cam member 280 against the other inner frame facing piece 250 of the measuring arm 230 . As a result, friction is generated between the other inner frame facing piece 250 and the cam member 280, and the measuring arm 230 and the cam member 280 are rotated integrally.

Suppose now that the probe 240 and the work are in contact with each other in the direction perpendicular to the axis of the measuring arm 230, and the probe 240 is pushed by the work (for example, see FIG. 6). Then, the measurement arm 230 rotates about the arm support shaft 220, and the cam member 280 rotates together with the measurement arm 230. As shown in FIG. Since the leg portion 275 of the transmission shaft member 270 is in contact with the contactor 281 of the cam member 280, the transmission shaft member 270 is pushed by the contactor 281 of the cam member 280, and the transmission shaft member 270 moves to the other end side by that amount. move to

Inside the body housing portion 300, as shown in FIG. 3, a linear encoder (linear encoder) 310 and an electrical component portion 340 are provided.
The linear encoder 310 is a so-called linear encoder (linear encoder) that has a scale 320 and a detector 330 and detects relative displacement between the scale 320 and the detector 330 . Here, the scale 320 is a movable body, and the other end surface of the transmission shaft member 270 and the one end surface of the scale 320 are in contact with each other. The end surface of the other end of the transmission shaft member 270 and the end surface of the one end of the scale 320 may be fixedly connected by screwing or adhesion so that they do not separate, or the scale 320 may be attached to the one end by a spring or the like. You can force it.

The scale 320 advances and retreats together with the advance and retreat of the transmission shaft member 270 . The detection unit 330 is fixedly installed in the main housing unit 300 as a fixed body. The detection unit 330 detects the displacement (or absolute position) of the scale 320 and sends it to the electrical equipment unit 340 .

As an encoder, various methods such as a capacitance type, a photoelectric type, and an electromagnetic induction type may be adopted.
However, in order to maximize the advantage of this embodiment, it is preferable to use an absolute type (absolute position detection type) linear encoder (linear encoder) rather than an increment type.
The test indicator 100 of this embodiment is of a universal type, and has the advantage of being able to rotate the head portion 200 to change the operating direction of the probe 240 and to set the angle of the measuring arm 230 arbitrarily. be. For example, as shown in 1A and 1B in FIG. 1, the unevenness of the workpiece may be measured with the posture of the measuring arm 230 set at 90 degrees. (Of course, the angle of the measuring arm 230 is arbitrary and may be other than 90 degrees.) In this case, it is necessary to set the zero point (origin setting). ) is desirable.

FIG. 5 is a functional block diagram of the electrical unit 340. As shown in FIG.
The electrical component section 340 includes a displacement conversion section 350 and a display control section 370 .
The displacement conversion unit 350 converts (converts) the linear displacement of the transmission shaft member 270 into a displacement amount d of the probe 240 in the direction perpendicular to the axial direction of the measurement arm 230 .
Let L1 be the length from the probe 240 to the center of rotation of the measurement arm 230 (see FIG. 6). The length L1 of the measurement arm 230 is set and stored in the measurement arm length storage section 360 attached to the displacement conversion section 350 . Also, in the cam member 280, the distance from the rotation center to the contactor 281 is r (see FIG. 6). Let Ds be the value detected by the linear encoder 310 . (Ds corresponds to the amount of displacement of the transmission shaft member 270.)
At this time, the displacement conversion unit 350 obtains the displacement amount d of the tracing stylus 240 as follows.
d = (L1/r) Ds
This displacement amount d is displayed on the display unit 400 as a measured value.

Note that the measurement arm 230 may be replaced according to the workpiece. Assuming that the length of the measurement arm 230 after replacement is L2, the length of the measurement arm 230 after replacement is set and input to the measurement arm length storage unit 360 . At this time, the displacement amount d of the probe 240 is obtained as follows.
d = (L2/r) Ds

Further, the displacement conversion unit 350 corrects the displacement amount d to a value in the direction perpendicular to the surface to be measured (that is, unevenness or undulation of the surface to be measured) according to the angle θ between the surface to be measured and the measurement arm 230. may have a function to
In order to accurately measure the unevenness of the surface to be measured, it is desirable to install the test indicator 100 so that the measuring arm 230 and the surface to be measured are parallel, as illustrated in FIG. 7A. However, due to unavoidable circumstances (for example, the workpiece has a special shape), it may be necessary to form an angle θ between the measurement arm 230 and the surface to be measured, as shown in FIG. 7B. In this case, the angle θ between the measurement arm 230 and the surface to be measured is set and input to the displacement conversion section 350 . Then, the displacement conversion unit 350 multiplies the displacement amount d of the stylus 240 by the correction coefficient (cos θ) to obtain a correct measurement value (unevenness of the surface to be measured).

The display unit 400 is a display panel such as liquid crystal or organic EL. The display control unit 370 causes the display unit 400 to display the measured values.

According to the test indicator 100 of this embodiment having the above configuration, the following effects can be obtained.
(1) Conventional test indicators transmit minute rotations of the measurement arm 230 while magnifying them with a gear train to rotate the pointer at the final stage, so the accumulation of mechanical errors affects the measured values. There was a problem of giving Although it has been proposed to incorporate a rotary encoder into the test indicator, if the minute rotation of the measuring arm 230 is magnified by the gear train to the extent that it can be detected by the rotary encoder, the accumulation of mechanical errors still becomes a problem. was
In this regard, in this embodiment, the rotation of the measurement arm 230 is converted into linear displacement, and then the displacement of the transmission shaft member 270 is detected by the linear encoder 310 . As a result, the accumulated mechanical error in the displacement transmission path from the measuring arm 230 to the encoder is minimized, improving detection accuracy.

(2) In the conventional test indicator, minute rotation of the measurement arm 230 is transmitted while being magnified by the gear train, and the rotation of the measurement arm 230 is transmitted in a direction perpendicular to the axial direction of the measurement arm 230 according to the gear ratio. was converted into the displacement amount d of the tracing stylus 240 at . Since the gear mechanism once assembled cannot be replaced by the user, the length of the measuring arm 230 is determined for each individual test indicator and cannot be changed. However, some users did not realize that the conversion rate was fixed, and erroneously changed the long measurement arm 230 and the short measurement arm 230 depending on the workpiece.
In this regard, in this embodiment, if the length L of the measurement arm 230 is set in the displacement conversion section 350, the measured value can be correctly converted according to the length of the measurement arm 230. FIG. Therefore, the user only needs to prepare measuring arms 230 having different lengths according to need without preparing multiple types of test indicators 100 according to the workpiece. This not only reduces costs for the user, but also reduces the number of product types for the manufacturer, thereby reducing manufacturing and management costs.

It should be noted that the present invention is not limited to the above-described embodiments, and configurations appropriately modified without departing from the spirit of the present invention belong to the technical scope of the present invention.

100... test indicator,
200 ... head part,
210... Outer frame opposing piece, 220... Arm support shaft,
230... Measuring arm, 240... Probe,
250... Inner frame opposing piece,
260...Through hole, 261...Spring,
270... transmission shaft member, 275... leg portion, 280... cam member, 281... contactor, 285... disc spring,
300 ... body housing portion,
310... linear encoder,
320... scale, 330... detector,
340... Electrical part,
350... Displacement conversion unit, 360... Measurement arm length storage unit, 370... Display control unit,
400... Display unit

Claims (3)

a measuring arm having a probe at one end;
a head section that pivotally supports the other end side of the measurement arm with an axis orthogonal to the axial direction of the measurement arm as a rotation axis;
a transmission shaft member inserted through the head portion so as to linearly advance and retreat in the head portion in conjunction with the rotation of the measurement arm;
a body housing portion that holds the head portion so as to rotate about the transmission shaft member;
a linear encoder that is provided in the body housing portion, has a movable body that linearly advances and retreats in conjunction with the advance and retreat of the transmission shaft member, and detects displacement of the movable body;
a displacement conversion unit that converts the displacement of the movable body into displacement in a direction perpendicular to the axial direction of the measurement arm of the probe;
and a display unit that displays the displacement of the stylus obtained by the displacement conversion unit. A test indicator according to claim 1, wherein
The displacement conversion unit is provided with a measurement arm length storage unit for setting and storing the length of the measurement arm,
A test indicator, wherein the displacement conversion section changes the conversion ratio according to the length of the measurement arm. The test indicator according to claim 1 or claim 2,
A test indicator, wherein the linear encoder is an absolute encoder.

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