JP7129826B2 - Digital micrometers and micrometers - Google Patents

Description

The present invention relates to digital micrometers and micrometers .

In recent years, the development and production of permanent magnet synchronous motors has been accelerated partly due to the increasing demand for hybrid vehicles and electric vehicles. Strong magnets are essential for high-performance permanent magnet synchronous motors. Therefore, the machining accuracy of the magnets incorporated in the permanent magnet synchronous motor becomes a problem.

In general, small measuring instruments such as micrometers and vernier calipers are convenient and suitable for measuring the machining accuracy of small parts, but the frames and other main parts of small measuring instruments are made of iron (cast iron). Then, just by bringing the object to be measured, which is a strong magnet, close to the small measuring instrument, the two are strongly attached to each other. Therefore, conventionally, a large-sized measuring machine such as a three-dimensional measuring machine had to be used when the part was a strong magnet, even if it was a small part. This has a not insignificant effect on production efficiency and manufacturing costs.

Various miniature measuring instruments suitable for use in magnetic fields have been proposed so far. However, there was no digital type that could stand up to practical use.

Japanese Utility Model Laid-Open Showa 51-82480 Japanese Patent Laid-Open No. 60-236001 Japanese Utility Model Laid-Open Showa 50-50053 JP 2009-243883 Patent 4072282 Utility model registration No. 3184265 Japanese Patent Laid-Open No. 58-115301

In order to make a miniature measuring instrument suitable for use in a magnetic field, it is conceivable that the main parts of the miniature measuring instrument are made of non-magnetic materials. However, strong non-magnetic materials are difficult to cut. For example, in a micrometer, it is necessary to cut a high-precision male thread on the spindle and tap a high-precision female thread on the body frame, but it is difficult to do this with non-magnetic materials.
There is a need for a digital micrometer that can measure ferromagnetic objects with practical accuracy.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital micrometer suitable for measuring ferromagnetic objects.

The digital micrometer of the present invention is
a body frame having an anvil inside one end of the U-shape;
a spindle provided on the other end side of the body frame so as to be axially advanceable and retractable so as to advance and retreat with respect to the anvil, and having a contact on one end face;
a thimble portion provided on the other end side of the main body frame for receiving the other end of the spindle and converting rotational operation into linear motion of the spindle;
A digital micrometer comprising: a main scale that moves integrally with the spindle; and an encoder that is disposed on the body frame and has a detection head that detects a relative position or relative displacement amount with respect to the main scale,
The body frame and the spindle are made of a non-magnetic metal material,
The thimble part is
an inner sleeve having a slit along the axis and fixedly provided on the other end side of the body frame;
an outer sleeve fitted around the inner sleeve so as to be rotatable in the circumferential direction and having a spiral groove on its inner peripheral surface;
An engaging pin fixedly provided on the spindle is engaged with the spiral groove through the slit.

In the present invention,
The body frame is made of austenitic stainless steel, pure aluminum, or a non-magnetic aluminum alloy,
The spindle is preferably made of austenitic stainless steel.

In the present invention,
The anvil and the contact are preferably made of ceramic.

In the present invention,
A guide bush for bearing the spindle is provided on the other end side of the body frame near the anvil,
The guide bush is preferably made of brass.

In the present invention,
The inner sleeve is preferably made of brass, pure aluminum, non-magnetic aluminum alloy, or austenitic stainless steel.

In the present invention,
The encoder is preferably a capacitive encoder, a photoelectric encoder, an electromagnetic induction encoder, or a magnetic encoder.

In the present invention,
The body frame is made of austenitic stainless steel,
The spindle is made of austenitic stainless steel,
The inner sleeve is made of brass,
The encoder is preferably a capacitive encoder.

It is a front view showing the appearance of a digital micrometer. It is a partial cross-sectional view showing the internal structure of a digital micrometer. It is an exploded perspective view of a thimble part. It is an exploded perspective view of a detection part.

An embodiment of the present invention will be illustrated and described with reference to the reference numerals attached to each element in the drawings.
(First embodiment)
A first embodiment of the digital micrometer 100 of the present invention will be described.
FIG. 1 is a front view showing the appearance of a digital micrometer 100. FIG.
FIG. 2 is a cross-sectional view showing the internal structure of the digital micrometer 100. As shown in FIG.
The digital micrometer 100 includes a body frame 200 , a spindle 300 , a thimble section 400 and a detection section 500 .

The body frame 200 is generally U-shaped, and an anvil 210 is provided inside one end of the U-shape.
A spindle 300 is provided on the other end side of the body frame 200 so as to be able to advance and retreat. At this time, on the other end side of the body frame 200 , the guide bush 220 is attached to the side closer to the anvil 210 , and the thimble portion 400 is attached to the side farther from the anvil 210 .
A display panel 201 is arranged on the front side of the body frame 200 . A digital display section 230 and a plurality of operation switches 240 are arranged on the display panel 201 . The display panel 201 is made of a non-magnetic material such as plastic or resin.

Here, the body frame 200 is preferably made of austenitic stainless steel. Austenitic stainless steel is a strong, non-magnetic material.

Alternatively, body frame 200 may be made of pure aluminum or a non-magnetic aluminum alloy.

Also, the anvil 210 is preferably made of ceramic. An example of the composition of the ceramic is zirconia.

Guide bushing 220 is preferably made of brass. Brass is a non-magnetic material and a free-cutting material.
Note that the guide bush 220 may be made of austenitic stainless steel.
However, it is considered preferable to provide a hardness difference in the relationship between the sliding shaft and the hole.
In the case of a micrometer, it is preferable to set the hardness of the spindle to be high and the hardness of the guide bush to be low so that the guide bush is worn during durability.
Austenitic stainless steel cannot be hardened. This is because quenching causes a slight magnetism or softening. Therefore, austenitic stainless steel cannot control the difference in hardness due to the difference in quenching. Therefore, different materials must be selected for the spindle and the guide bush. If the spindle 300 is made of austenitic stainless steel, the guide bush 220 is preferably made of brass.

The spindle 300 is generally a long rod-like cylindrical body that is made straight.
A contact 310 is provided on one end surface of the spindle 300 . When measuring an object to be measured, the spindle 300 is advanced and retracted to sandwich the object to be measured between the contactor 310 and the anvil 210 . A middle portion of the spindle 300 is supported by the guide bush 220 , and the other end of the spindle 300 is inserted into the thimble portion 400 .

An engaging piece member 330 is connected to the other end of the spindle 300 .
The piece member is an annular member and fixedly fitted on the other end of the spindle 300 . Specifically, a taper 320 having a reduced diameter is provided at the other end of the spindle 300 , and a tapered hole 331 for receiving the other end of the spindle 300 is provided in the engaging piece member 330 . An engagement pin 332 is press-fitted into the engagement piece member 330 so as to protrude in a direction perpendicular to the axial direction of the spindle 300 .

In this embodiment, the spindle 300 does not have a male thread, and the spindle 300 itself does not rotate. The spindle 300 advances and retreats in the axial direction without rotating.

Spindle 300 is preferably formed of austenitic stainless steel.

Also, like the anvil 210, the contactor 310 is preferably a thin chip made of ceramic.

The engaging piece member is preferably made of brass.

FIG. 3 is an exploded perspective view of the thimble portion 400. FIG.
The thimble part 400 is a generally tubular unit provided on the other end side of the body frame 200 . The other end side of the spindle 300 is received inside the thimble portion 400 .
The user advances and retreats the spindle 300 by rotating the thimble portion 400 .
The thimble portion 400 has an inner sleeve 410 , an outer sleeve 420 and a cover member 430 .

The inner sleeve 410 is a cylindrical member with both ends open and has one slit 411 along the axis. One end of the inner sleeve 410 is fixedly attached to the other end of the body frame 200 . The other end of the spindle 300 is inserted through the opening on the one end side of the inner sleeve 410 . At this time, the other end of the spindle 300 is inserted into the inner sleeve 410 and the engagement pin 332 is press-fitted into the engagement piece member 330 through the slit 411 so that the engagement pin 332 protrudes from the slit 411 .
The inner diameter of the inner sleeve 410 is designed to be the same as the outer diameter of the engagement piece member 330 .
The engagement piece member 330 slides inside the inner sleeve 410 together with the spindle 300 while the engagement piece member 330 is supported by the inner peripheral surface of the inner sleeve 410 . At this time, since the engaging pin 332 protrudes from the slit 411, the spindle 300 moves forward and backward while being prevented from rotating by the engaging pin 332. As shown in FIG.

A cap 412 is screwed into the opening on the other end side of the inner sleeve 410 .

The outer sleeve 420 is a cylindrical member with both ends opened, and the outer sleeve 420 is fitted to the outside of the inner sleeve 410 . At this time, the outer sleeve 420 is rotatable in the circumferential direction with respect to the inner sleeve 410 . A single spiral groove 421 is formed in the inner peripheral surface of the outer sleeve 420 . An engaging pin 332 is engaged with the spiral groove 421 .

The cover member 430 is a cover that covers the outer sleeve 420 and has a knurled surface. There is no slippage between the cover member 430 and the outer sleeve 420, and the cover member 430 and the outer sleeve 420 rotate integrally.

When the cover member 430 is rotated in the circumferential direction, the outer sleeve 420 rotates in the circumferential direction together with the cover member 430 . Here, the engaging pin 332 is engaged with the spiral groove 421 on the inner circumference of the outer sleeve 420 , and the rotation of the engaging pin 332 is restricted by the slit 411 of the inner sleeve 410 . Therefore, the engagement pin 332 is pushed by the spiral groove 421 and advances and retreats by rotating the cover member 430 . Since the engagement pin 332 , the engagement piece member 330 and the spindle 300 are integrated, the spindle 300 also advances and retreats as the engagement pin 332 advances and retreats.

Since the spindle 300 is made of austenitic stainless steel, it is difficult to thread the spindle itself as a mechanism for moving the spindle 300 back and forth. In this regard, the present embodiment employs a configuration in which the engagement pin 332 whose rotation is restricted is moved by the spiral groove 421 of the outer sleeve 420 .

Here, the inner sleeve 410 is preferably made of brass.
Brass is a non-magnetic material and a free-cutting material. Since the inner sleeve 410 is a bearing material, machining accuracy of the inner diameter is required. A slit 411 is formed in the inner sleeve 410, and the slit 411 secures the straightness of the movement of the spindle 300 and prevents rotation. As will be described later, in detecting the movement of the spindle 300 with the encoder 510, in this embodiment, the main scale 511 is directly or indirectly attached to the spindle. Therefore, even a slight rotation of the spindle 300 affects the detection accuracy of the encoder. From this point of view, it is considered that brass is preferable as the material for the inner sleeve 410 because it is difficult to work with austenitic stainless steel.
Alternatively, inner sleeve 410 may be made of pure aluminum or a non-magnetic aluminum alloy. Pure aluminum or aluminum alloys have large thermal expansion (large linear expansion coefficient) and slightly inferior rigidity (Young's modulus), but they have the advantage of being easy to process and lightweight. . If the body frame 200 is made of austenitic stainless steel, the inner sleeve 410 may be made of pure aluminum or an aluminum alloy in consideration of the overall weight balance. It is desirable that a small measuring instrument (small tool) has a weight that does not become a burden even if it is held in one hand for a long time, and it is also safe and less likely to be damaged when dropped.
Conversely, if the body frame 200 is made of pure aluminum or a non-magnetic aluminum alloy, the inner sleeve 410 should be made of brass.
Additionally, inner sleeve 410 may be formed of austenitic stainless steel. Among non-magnetic materials, austenitic stainless steel is preferable as a material for measuring instruments because of its small thermal expansion and high strength. However, there are problems that processing is difficult and weight increases.

Also, the outer sleeve is a resin molded product (for example, liquid crystal polymer). It is preferable that the cover member is formed of a resin molded article.

Next, the configuration of the detection unit 500 will be described.
FIG. 4 is an exploded perspective view of the detection unit 500. FIG.
The detection section 500 has an encoder 510 and a head fixing section 530 . The encoder 510 is a linear encoder 510 and has a longitudinal main scale 511 and a detection head 512 .
The main scale 511 and the detection head 512 are relatively movable along the longitudinal direction of the main scale 511 , and the detection head 512 detects the position or displacement with respect to the main scale 511 .
In this embodiment, the detection head 512 is fixedly provided with respect to the body frame 200, and the main scale 511 advances and retreats together with the spindle 300. As shown in FIG.

Here, the linear encoder 510 is capacitive. That is, the main scale 511 is provided with grid electrodes arranged at a predetermined pitch in the longitudinal direction on a glass substrate.
The detection head 512 has a plurality of sets of transmission electrodes and reception electrodes provided on a glass substrate. Then, a predetermined AC signal is transmitted from the transmission electrode of the detection head 512 to the grid electrode of the main scale 511, and the potential of the grid electrode induced by this AC signal is read by the reception electrode. Thereby, the detection head 512 detects the position or displacement with respect to the main scale 511 .

A flat surface is formed on the side surface of the spindle 300 and this flat surface serves as the scale base 520 . A main scale 511 is attached and fixed to a scale base 520 . Thereby, the main scale 511 advances and retreats together with the spindle 300 .

The head fixing portion 530 has a head holding plate 531 , a holding plate 533 and a fixing plate 534 .

A detection head 512 is attached to one surface (back surface) of the head holding plate 531 . A plurality of (three) protrusions 532 are formed on one surface of the head holding plate 531 at positions that do not interfere with the detection head 512 , and the tips of the protrusions 532 slidably contact the main scale 511 . As a result, the detection head 512 faces the main scale 511 with a predetermined gap therebetween.

The pressing plate 533 is a leaf spring that presses the other surface (front surface) of the head holding plate 531 to press the head holding plate 531 against the main scale 511 . The pressing plate 533 presses the head holding plate 531 from the front surface with a cantilever-like leaf spring.

The fixing plate 534 holds the pressing plate 533 in a cantilevered manner. Furthermore, the fixing plate 534 is screwed to the mounting seat 250 formed on the body frame 200 .

For example, the head fixing portion 530, the head holding plate 531, the pressing plate 533, and the fixing plate 534 are made of austenitic stainless steel.

A flexible printed circuit board 540 is provided inside the body frame 200, and includes an encoder 510 (main scale 511, detection head 512), an external output terminal 541, a GND terminal 542, an arithmetic processing circuit, a digital display section 230, and an operation switch 240. Wiring is done.

In the present embodiment, as a movement mechanism for the spindle 300, a configuration is adopted in which the engagement pin 332 is moved by the rotation of the spiral groove 421. As shown in FIG. However, in this configuration, since the accuracy of the spiral groove 421 is limited, it is difficult to precisely obtain the displacement amount of the spindle 300 from the rotation amount of the thimble portion 400 .
In this respect, the present embodiment employs a configuration in which the encoder 510 detects the displacement of the spindle 300 .

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention.
As an encoder, a capacitive linear encoder is exemplified.
In addition, a photoelectric encoder, an electromagnetic induction encoder, and a magnetic encoder can be used.

As for the encoder, it would be preferable to use a glass substrate for both the main scale and the detection head, as in the above embodiment.
However, only the chip of the arithmetic processing circuit may be surrounded by a magnetic shield material (for example, ferromagnetic metal). If the chip is sufficiently small, the force (magnetic force) generated between it and the object to be measured (workpiece), which is a strong magnet, will not be so large.

100... Digital micrometer,
200... body frame,
210... anvil, 220... guide bush, 230... digital display unit, 240... operation switch, 250... mounting base,
300... Spindle, 310... Contact, 320... Taper,
330... Engagement piece member, 331... Tapered hole, 332... Engagement pin,
400... Thimble part,
410... inner sleeve, 411... slit, 412... cap,
420... Outer sleeve, 421... Spiral groove,
430 ... cover member,
500 ... detector,
510... Encoder, 511... Main scale, 512... Detection head,
520... Scale pedestal,
530 ... head fixing part,
531...Head holding plate, 532...Protrusion, 533...Retaining plate, 534...Fixing plate.
540... Flexible printed circuit board.

Claims (7)

a body frame having an anvil inside one end of the U-shape;
a spindle provided on the other end side of the body frame so as to be axially advanceable and retractable so as to advance and retreat with respect to the anvil, and having a contact on one end face;
a thimble portion provided on the other end side of the main body frame for receiving the other end of the spindle and converting rotational operation into linear motion of the spindle;
A digital micrometer comprising: a main scale that moves integrally with the spindle; and an encoder that is disposed on the body frame and has a detection head that detects a relative position or relative displacement amount with respect to the main scale,
The body frame and the spindle are made of a non-magnetic metal material,
The thimble part is
an inner sleeve having a slit along the axis and fixedly provided on the other end side of the body frame;
an outer sleeve fitted around the inner sleeve so as to be rotatable in the circumferential direction and having a spiral groove on its inner peripheral surface;
an engagement pin fixedly provided on the spindle is engaged with the spiral groove through the slit ;
moreover,
The spindle is made of austenitic stainless steel,
The inner sleeve is made of brass, pure aluminum, or a non-magnetic aluminum alloy,
At the other end of the body frame, a cylindrical guide bush is provided on the side near the anvil for receiving and bearing the spindle inside, and the guide bush is made of brass.
A digital micrometer characterized by: The digital micrometer of claim 1, wherein
The body frame is made of austenitic stainless steel, pure aluminum, or non-magnetic aluminum alloy .
A digital micrometer characterized by : In the digital micrometer according to claim 1 or claim 2,
A digital micrometer, wherein the anvil and the contactor are made of ceramic. In the digital micrometer according to any one of claims 1 to 3 ,
A digital micrometer, wherein the encoder is a capacitive encoder, a photoelectric encoder, an electromagnetic induction encoder, or a magnetic encoder. In the digital micrometer according to any one of claims 1 to 4 ,
The body frame is made of austenitic stainless steel,
A digital micrometer, wherein the encoder is a capacitive encoder. body frame and
a spindle provided in the main body frame so as to move forward and backward in the axial direction and having a contact on one end face;
a thimble portion provided on the body frame for receiving the other end of the spindle and for converting rotational operation into linear motion of the spindle ;
A digital micrometer comprising an encoder that detects the position or displacement of the spindle ,
The body frame and the spindle are made of a non-magnetic metal material,
The thimble part is
an inner sleeve having a slit along the axis and fixedly provided on the other end side of the body frame;
an outer sleeve fitted around the inner sleeve so as to be rotatable in the circumferential direction and having a spiral groove on its inner peripheral surface;
an engagement pin fixedly provided on the spindle is engaged with the spiral groove through the slit ;
moreover,
The spindle is made of austenitic stainless steel,
The inner sleeve is made of brass, pure aluminum, or a non-magnetic aluminum alloy,
In the main body frame, a cylindrical guide bush is provided on the far side from the thimble portion for receiving and bearing the spindle inside, and the guide bush is made of brass.
A digital micrometer characterized by : body frame and
a spindle provided in the main body frame so as to move forward and backward in the axial direction and having a contact on one end face;
a thimble portion provided on the body frame for receiving the other end of the spindle and for converting rotational operation into linear motion of the spindle,
The body frame and the spindle are made of a non-magnetic metal material,
The thimble part is
an inner sleeve having a slit along the axis and fixedly provided on the other end side of the body frame;
an outer sleeve fitted around the inner sleeve so as to be rotatable in the circumferential direction and having a spiral groove on its inner peripheral surface;
an engagement pin fixedly provided on the spindle is engaged with the spiral groove through the slit ;
moreover,
The spindle is made of austenitic stainless steel,
The inner sleeve is made of brass, pure aluminum, or a non-magnetic aluminum alloy,
In the main body frame, a cylindrical guide bush is provided on the far side from the thimble portion for receiving and bearing the spindle inside, and the guide bush is made of brass.
A micrometer characterized by :

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