JPS61253403A - Inside diameter gauge - Google Patents

Abstract

PURPOSE:To measure automatically and accurately bore diameter, etc., by installing a self-aligning mechanism and introducing a measuring mechanism into a specimen hole with a receding feeler. CONSTITUTION:A spindle 7 is installed free to move forward and backward inside a cylindrical body 5, and measuring mechanism set to forward and backward motions of a stylus 10 in the direction perpendicular direction to the axis of the spindle 7, following the movement of this spindle 7, displacing mechanism allowing the stylus 10 to forward and backward in the direction perpendicular to said axis, advancing and retarding mechanism allowing the measuring mechanism to advance and recede to and from an inside diameter measuring position of the specimen hole and self- aligning mechanism are installed. When the measuring mechanism is advanced and receded by the advancing and receding mechanism, the measuring mechanism is supported in alignment with the axis line peculiar to this apparatus. Further, when the inside diameter of the specimen hole is measured, the supporting effect of the measuring mechanism is released and the measuring mechanism is aligned with the axis line of the specimen hole, following contact of the stylus 10 with the inside surface of the specimen hole. Thus, the bore diameter can be measured automatically and accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an inner diameter measuring device for measuring the hole diameter of a workpiece, and more particularly to an inner diameter measuring device equipped with a self-aligning mechanism.

[Technical background of the invention and its problems]

Conventionally, as an internal diameter measuring device for measuring the hole diameter of a workpiece, a dial gauge is attached to one end of a cylindrical body, and a spindle that pushes the measuring shaft of the dial gauge is slidably built into the body. However, there is one in which a measuring element is provided at the other end of the old main body to follow the movement of the spindle and move back and forth in a direction perpendicular to the axis of the spindle.

Normally, this inner diameter measuring device has a spring interposed between the main body and the spindle so as to always bias the probe in the direction of its protrusion, but the biasing force of this spring cannot be adjusted from the outside. There are many possibilities. For example, if you want to change the measurement pressure due to the material of the object to be measured, you have no choice but to replace the spring. Therefore, as a means of changing the bias of this spring, Japanese Patent Laid-Open No. 57-179702
The publication discloses a configuration in which the set length of the spring can be changed arbitrarily using an adjustment mechanism, but since the probe is always protruding due to the bias of this spring, the probe cannot be moved from the object to be measured. When inserting it into the hole, it had to be retracted using a manual mechanism.

Furthermore, Japanese Patent Application Laid-Open No. 59-85901 discloses a device in which the spring is biased in the opposite direction so that the probe is always in the retracted position.
After inserting the probe into the hole, the probe must be pushed out using a manual mechanism, making it difficult to maintain stable measurement pressure.

Further, in the technique disclosed in Japanese Patent Publication No. 58-32641, since the movable filler is constantly urged to protrude by a spring, a series of skilled manual operations are required, and automation is difficult.

There are also displacement meters that provide electrical output in place of dial gauges to improve reliability against misreadings and recordings, but they are still manually operated and cannot be operated automatically. Automatic measurement was impossible because it could not be inserted into the hole and it could not be self-aligned during measurement. There are internal diameter measuring devices, but their measuring range becomes narrower as they become more precise, and they also require more specialized power and are more expensive.1. It is difficult to align the air micros and electric micros with the holes, so versatility cannot be expected.

In short, conventional inner diameter measuring devices cannot automatically control the protrusion and retraction of the probe using external power, and it is difficult to change the measurement pressure from the outside.
It could not be used as an automatic measuring device. On the other hand, methods that directly and automatically measure using air microscopy or electric microscopy have a narrow measurement range, and although they can be used exclusively for specific inner diameter dimensions, they are highly versatile and can be used over a wide range of measurement ranges. Since there is no automatic measurement function, they had no choice but to rely on expensive specialized equipment.

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention is directed to configuring an inner diameter measuring device so as to be able to automatically and highly accurately measure the pore diameter of an object to be measured.

[Summary of the invention]

A measuring mechanism in which a spindle is housed in a cylindrical body so that it can move forward and backward in the axial direction thereof, and a measuring element follows the movement of the spindle and moves forward and backward in a direction perpendicular to the axis of the spindle, and the spindle. A self-aligning mechanism is provided in the inner diameter measuring device, which has a moving mechanism that moves the measuring head in a direction perpendicular to the axis of the spindle, and a moving mechanism that moves the measuring mechanism back and forth toward the inner diameter measuring position of the measuring hole. When the measuring mechanism is moved forward and backward by the advance/retreat mechanism, the measuring mechanism is aligned and supported on the axis specific to the device, and when the inner diameter of the measuring hole is measured, the support of the measuring mechanism is released and the measurement is performed. By aligning this measuring mechanism on the axis of the measuring hole as the child contacts the inner surface of the measuring hole, the hole diameter can be measured automatically and with high precision.

[Embodiments of the invention]

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

FIGS. 1 and 2 show a front and side view of an inner diameter measuring device which is an embodiment of the present invention, and FIGS.
This inner diameter measuring device, the main parts of which are shown in the figure, consists of a measuring mechanism, a moving mechanism that moves the spindle, probe, etc. that make up this measuring mechanism, an advancing/retracting mechanism that moves the entire measuring mechanism, and a self-aligning mechanism. It is comprised of a control section that controls the operations of the moving mechanism and the advancing/retracting mechanism.

Each of these configurations will be described below.

A. Measuring mechanism: □ The measuring mechanism consists of a first cylindrical body ω, a second cylindrical body ■ which is removably and coaxially screwed into one end of the first cylindrical body ■, and a second cylindrical body ■ which is screwed coaxially with the first cylindrical body ω, and the other end of the first cylindrical body ■. (to the third cylinder that is coaxially screwed together with a spacer ■ in between)
A pair of bearings (6a) and (6b) installed in the cylindrical body ■ allow the spindle ■ to move coaxially with the cylindrical body ■ and move back and forth in its axial direction. Supported. Adjacent to this spindle (in the third cylinder), a length measuring unit (2) consisting of a magnetic scale is installed via a bushing (2), and its tip (10) comes into contact with one end of the spindle (2). It looks like this. From this length measuring unit ■, as shown in Figure 3, a cable (11) connecting to a display device (not shown) is connected to the third cylinder).
The output is displayed or recorded on a display device.

Also, inside the second cylinder (2), an actuating body (1) is in point contact with the other end surface of the spindle (1) via a small diameter ball (12).
3) is slidably inserted. This operating body (13)
has a tapered surface (1
4) is formed. Also, on the outside of the tip of the second cylinder (2), as shown in FIG.

Three cylindrical bodies (15) are protruded in the radial direction with their outer surfaces equally spaced at 120@, and inside each of these cylindrical bodies (15).

A stepped columnar measuring element (16) is slidably inserted in its axial direction. Each measuring element (16) has a large-diameter end face formed into a tapered surface that makes line contact with the tapered surface (14) of the actuating body (13), and a small-diameter portion of each of the cylindrical bodies (15). ) The tapered surface of the large diameter part is always connected to the actuating body (13) by a compression coil spring (18) that passes through the end face of the cap nut (17) that is screwed into the tip of the cap nut (17) and is attached around the middle part of the cap nut (17). It comes into pressure contact with the tapered surface (14) of. In addition, at the tip of the small diameter portion protruding from the cap nut (17), extending in the same direction as the axis of the cylindrical body (2),
An anvil (19) is provided that comes into contact with the inner surface of the hole (H) of the object to be measured (W). In order to properly abut this anvil (19) on the inner surface of the hole (H), each measuring element (1
A key groove (21) is provided on the side surface of the probe (6) along the axis of the probe (16) to slidably fit with a key (20) inserted from the end face side of the second cylinder (2). It is being

B. Moving mechanism: □ The moving mechanism is, as shown in FIG.
It is provided with a pair of air cylinders (31) extending parallel to the cylindrical body 0 and attached to a pair of joint plates (30) which are screwed so as to face each other on both left and right ends of the cylinder. The tip of each rod (32) of this air cylinder (31) is located in the direction of the probe (16), and the tip of each rod (32) is connected to the outside of the first cylinder (2) via a joint (33). A ring-shaped external engagement member (34) that is slidably fitted to the side surface is connected. The side surface of the first cylindrical body (2) where this external engagement member (34) is located has a long and narrow hole (3) extending in the axial direction of this cylindrical body (2).
5) are formed symmetrically through the first cylindrical body (3), and in correspondence with the external engaging member (34), the external engaging member (34) is integrally attached to the spindle (2) by screwing, press-fitting, gluing, etc. An internal engagement member (36) is provided. This internal engagement member (36) and the external engagement member (34) are
As shown in FIG. 6, each air cylinder (31) is connected by a pair of pins (37) passing through each long hole (35).
The movement of the rod (32) is transmitted to the spindle (■).

Further, an external engaging member (3
4), a ring-shaped stopper (38) for regulating the retreating position of the rod (32) of each air cylinder (31) is screwed so that its mounting position can be adjusted, as shown in FIG. There is.

C0 self-aligning mechanism: □ The self-aligning mechanism is a first cylinder provided on the inside and outside of the first cylinder.
It consists of a centering part and a second centering part provided on the third cylindrical body.

The first Il core portion includes a tapered portion (40) that is integrally provided on the outer surface of the first cylindrical body (2) and has a large diameter in the backward direction of the rod (32) of the air cylinder (31); ■Second
A first guide hole (41) is provided with a guide hole (41) having a tapered side surface that is in close contact with the tapered surface of the tapered part (40), through which the cylinder body side end part (1) and the second cylinder part adjacent thereto are freely inserted.
It consists of a bracket (alignment seat) (42).

In addition, the second alignment part is connected to a pair of joint plates (3) on the third cylinder body).
0) A second bracket (alignment seat) (44) provided with a pair of tapered protrusions (43) located between them and erected in the same direction as the axis of the cylindrical body (2); As shown in the figure, it is screwed onto the tips of a pair of joint plates (30).

The guide plate (46) is provided with a pair of through holes (45) that fit into the large diameter portions of the pair of tapered protrusions (43).

Each bracket (42) of the first and second alignment parts, (
44) is attached to a first support plate (47) arranged behind the measuring mechanism and moving mechanism, and in particular, the second bracket (44) is attached to the guide hole (41) of the first bracket (4z). When the tapered surfaces of the tapered portion (40) are brought into close contact.

The large diameter portion of the pair of tapered protrusions (43) is connected to the guide plate (46).
), and between the substrate surface of this second bracket (44) and the guide plate (46),
It was installed so as to leave a gap between the two temples.

Further, when the measuring mechanism is installed in the vertical direction, the first bracket (42) automatically aligns and supports the lower part of the measuring mechanism by its own weight. At this time, the second bracket (44) automatically aligns the upper part of the measuring mechanism by fitting its pair of tapered projections (43) into the through holes (45) of the guide plate (46). , and the rotation around the axis of the cylindrical body (2) is restrained.

D. Advance/retreat mechanism: □ The advance/retract mechanism is parallel to the cylindrical body (■) of the measuring mechanism, and the air cylinder (31) and rod (50) of the moving mechanism are reversed in direction, and the base body (52) is moved by the joint (51). ) and the air cylinder (53) attached to this air cylinder (
and a second support plate (54) extending along the axis of the second support plate (53). This second support plate (54) is connected to the air cylinder (53).
) is connected to the rod (50) of the rod (50) via joints (55) and (56), and as the rod (50) moves forward and backward, it moves in the same direction as the rod (50) along a linear guide (not shown). It has become.

The second support plate (54) supports the measuring mechanism, the movement mechanism, and the self-aligning mechanism via the first support plate (47), and has a pair of protruding positions on the plate surface. The lock pins (57a), (57b) and the first support plate (47
), the first support plate (47) is positioned by a pair of positioning holes provided in the
8a) to (58c) are configured to removably fix this. Thus, when the first support plate (47) and this second support plate (54) are correctly positioned and fixed,
The measuring mechanism supported by the self-aligning mechanism is positioned correctly on the axis specific to this internal diameter measuring device.

E. Control unit: □ Inside the cylinder of the air cylinder (53) of the advance/retreat mechanism,
A magnet for detecting the rod position that moves together with the rod (50) is enclosed, and a reed switch (60) that cooperates with the magnet to control the forward stop position of the rod (50), and a reed switch (60) that controls the forward stop position of the rod (50), and a reed switch (60) that cooperates with the magnet to detect the rod position. Mechanism probe (1
6) is inserted into the hole (H) of the object to be measured (W) up to the measurement position (depth of the hole).
1) are attached by bands (62) and (63), respectively, and the reed switch (61) has a variable attachment position. Further, the tip of the air cylinder (53) faces a stopper (64) that is attached to the rod (50) of the air cylinder (53) in a variable mounting position to detect when the rod (50) has stopped moving backward. For example, the proximity sensor (65) is attached to the mounting bracket (66) from a magnetic sensor, etc.
) is attached.

The control device (not shown) includes the reed switch (60),
(61) and the outputs of the proximity sensor (65), the operation of the moving mechanism and the forward/backward mechanism, the input of the output from the length measuring unit (2) to the display device, etc. are controlled.

Next, the operation of this inner diameter measuring device will be described.

First, when the pair of air cylinders (31) of the moving mechanism are operated in the backward direction, the movement of the rods (32) of these air cylinders (31) is caused by the movement of the joint (33) and the external engagement member (34).
), the pin (37), and the internal engagement member (36) are transmitted to the spindle ■, ? 1! Measuring head of I-length unit (
10) and the compression coil spring (18).
The actuating body (13) is urged by the spindle (17).
) while following the movement of the probe (16) into the second cylinder ■
retreat toward the axis of

On the other hand, when the air cylinder (53) of the advancing/retracting mechanism is operated in the forward direction, the rod (50) of this air cylinder (53)
), the movement of the joints (55), (55), and the second support plate (
54).

The first and second self-aligning mechanisms are connected via the first support plate (47).
It is transmitted to the brackets (42) and (44), and the cylindrical body ■
While the measuring mechanism is supported by the first aligning part provided at the bottom of the body, the measuring mechanism is self-aligned by the first aligning part and the second aligning part provided above the cylindrical body. do.

The air cylinder (53) then stops at its forward end.

The stoppage of forward movement is detected by a reed switch (62) attached to the outside. At this time, the 1 m fixing mechanism is in a state where it is aligned and supported on the axis line unique to the device.

When the air cylinder (53) is operated in the backward direction from this state, the rod (50) of this air cylinder (53) moves and is attached to the second support plate (54) and this second support plate (54). The first support plate (47) is moved, and the first support plate (47) attached to the first support plate (47) is moved.
The measuring mechanism supported by the second brackets (42) and (44) is advanced toward the hole (H) of the object to be measured (W) positioned by a positioning mechanism (not shown).

Thus, the measuring head (1
6) reaches the measurement position in the hole (H), the reed switch (61) whose mounting position is adjusted to detect this is activated and a contact signal is sent to the control device. The control device controls the air cylinder (3) of the moving mechanism based on this contact signal.
1) issues a forward movement command to the air cylinder (
The rod (32) of 31) moves forward.

The advancement of the rod (32) of this air cylinder (31) is
Joint (33), external engagement member (34), pin (37),
It is transmitted to the spindle (2) via the internal engagement member (36), and causes the three probes (16) to respectively protrude toward the inner surface of the hole (H) via the operating body (13). On the other hand, the measuring stylus (10) of the length measuring unit (2) moves following the movement of the spindle (2).

Due to the protrusion of the three measuring points (16), each measuring point (1
When the anvil (19) provided at the tip of the anvil (19) comes into contact with the inner surface of the hole (H), the measuring mechanism stops at that position due to the frictional force generated between the anvil (19) and the inner surface.

Even if the measuring mechanism stops as described above, the air cylinder (5
3) continues to retreat, and the tapered part (40) of the first alignment part formed in the first cylindrical body (3) of the stopped measuring mechanism and the first
A gap is created between the bracket (42) and the bracket (42). At the same time, the fit between the tapered protrusion (43) provided on the second bracket (44) of the second alignment part and the guide plate (46) is also released. Thus, the rod (50) of the air cylinder (53)
) comes into contact with the end of the cylinder and stops, the measuring mechanism is released from the self-aligning mechanism and is moved by the anvil (19) provided on each measuring point (16). , are aligned and supported on the axis of the hole (H) with reference to the inner surface of the hole (H).

When the stopper (64) attached to the rod (50) of the air cylinder (53) comes into contact with the end of the cylinder as described above, the proximity sensor (65) detects the stopper (64).
Detects the approach of the proximity sensor (65), and based on the output signal sent from the proximity sensor (65), the control device latches the output of the length measuring unit (■), displays it on the display device, and further displays the output of the recording device. can be recorded.

When the measurement of the inner diameter of the hole (H) is completed, the air cylinder (
31) in the backward direction, and the air cylinder (53) in the forward direction. This air cylinder (
31) causes the probe (16) to follow the movement of the spindle (2) and retreat due to the bias of the compression coil spring (18), thereby releasing contact with the inner surface of the hole (H). This hole (
H) The measuring mechanism, which has been released from contact with the inner surface, is pulled up from the hole (H) while being supported by the first bracket (42), which is moved by the operation of the air cylinder (53), and is removed from the air cylinder (53). When the measuring mechanism stops at its forward end and the reed switch (62) is actuated, the measuring mechanism stops in a self-centered state at the first and second centering portions.

Configuring the inner diameter measuring device as described above has the following effects.

(a) When measuring the inner diameter of the hole (H) of the object to be measured (W).

This inner diameter measuring device is positioned so that the axis of the measuring mechanism aligned and supported by the self-aligning mechanism coincides with the axis of the hole (H) of the object to be measured (W) positioned by the positioning mechanism. However, when inserting the probe (16) into the hole (H), it is inserted in a backward position toward the axis of the measuring mechanism, so even if the measuring mechanism is eccentric with respect to the hole (H), it can easily be inserted. can be automatically inserted into. In other words, with conventional high-precision measuring devices using air microscopy, electric micros, etc., the gap between the inner surface of the hole and the hole is approximately several tens to 100 μs, so high-precision positioning is required. The measuring device uses a measuring tip (16 mm) with a sufficiently large stroke.
), automatic insertion is possible even if the measuring mechanism is eccentric with respect to the hole (H), and therefore the inner diameter of the hole (H) can be automatically measured even with a simple positioning mechanism.

(b) When the probe (16) reaches the measurement position in the hole (H), the moving mechanism operates to move the probe (16) into the hole (H).
At the same time, the self-aligning mechanism is released and the axis of the measuring mechanism automatically aligns with the axis of the hole (H), allowing stable and ideal measurements. be able to.

(c) When performing high-precision measurement, it is necessary to change the measurement pressure appropriately depending on the material of the object to be measured (W), but this inner diameter measuring device uses the air pressure of the air cylinder (31) to move the probe (16). Since it is brought into contact with the inner surface of the hole (H), the measured pressure can be arbitrarily and easily adjusted by changing the air pressure with a pressure regulating valve.

Compared to the conventional inner diameter measuring device having a measuring pressure adjustment mechanism using a spring, it is possible to easily perform highly accurate measurement according to the material of the object (W) to be measured.

(d) The cylindrical body ■ that constitutes the housing of the measuring mechanism is
There is a long hole (35) through which the pin (37) of the moving mechanism passes, but this long hole (35) is shielded from the outside of the cylindrical body (3) by an external engagement member (34), making the measuring mechanism a sealed structure. This prevents dust from entering the cylindrical body (2), allowing stable measurements to be made.

(e) The second cylindrical body (2) that supports the m constant (16) is configured to be detachable or replaceable, and the first support plate (47) that supports the entire measuring mechanism is detachable from the advancing/retracting mechanism. Moreover, since it is configured so that it can be easily positioned, prepare a cylindrical body with multiple types or a measuring mechanism, and select one of them that has a measurement range that corresponds to the inner diameter of the hole (H) of the object to be measured (W). Depending on the selection, a wide range of measurements can be performed.

For example, for 6 sets of cylinders with measurement intervals of 5III and 11, the inner diameter is 2.
0 to 50 WIm, 05 pairs of cylinders with a measurement interval of 10 nm, an inner diameter of 50 to 100 mm, and a measurement range of 25 to 1111 ■4 pairs of cylinders with an inner diameter of 100 to 200 mm, and matching the above measurement interval. By preparing three types of measuring mechanisms each equipped with a measuring unit (2), it is possible to measure an inner diameter range of 20 to 200 m without any problem. In this case, the cylinder ■ can be replaced by screwing it in, and the measuring mechanism can be replaced by simple positioning and tightening with a thumbscrew, so the cylinder ■ corresponding to the inner diameter of the hole (H) can be replaced. Alternatively, the measuring mechanism can be quickly and easily replaced.

Next, other embodiments will be described.

In the above embodiment, a pair of air cylinders were placed on both sides of the measuring mechanism to prevent unnecessary unbalanced torque from being applied to the spindle, but the air cylinder of this moving mechanism was placed coaxially with the measuring mechanism on its end. It may also be configured such that one piece is disposed and the connecting member is detoured and connected to the external engagement member.

In this case, since the measuring mechanism and the moving mechanism can be made thinner than those in the above embodiment, it can be applied to measuring the inner diameter of a small-diameter deep hole.

Further, the length measuring unit of the measuring mechanism is not limited to the magnetic scale, and may be of other types.

Furthermore, in the embodiment described above, the output of the length measuring unit is sent to the display device so that it can be displayed as 1 and can also be recorded.
This may be sent to an arithmetic unit for more advanced processing such as dimension and shape data.

〔Effect of the invention〕

A self-aligning mechanism is provided, and the measuring mechanism is aligned and supported on the device's own axis with the measuring point retracted, and inserted into the hole of the object to be measured. When the measurement position is reached, the above-mentioned alignment support is installed. When the measuring mechanism is released, the measuring element is made to protrude and come into contact with the inner side of the hole, and the measuring mechanism is automatically aligned on the axis of the hole, so even if the measuring mechanism is eccentric to the hole, it can be easily adjusted. It can be inserted automatically and can perform stable and highly accurate inner diameter measurements.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view of an internal diameter measuring device according to an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG.
The figure is a sectional view taken along the line ■-■ in FIG. 1, FIG. 4 is a bottom view of the measuring mechanism of the inner diameter measuring device shown in FIG. 1, and FIGS. 5 to 8 are a sectional view taken along the line ■-■ in FIG. 1. No ■－■
FIG.

Claims (7)

[Claims] (1) A measuring mechanism in which a spindle is installed inside a cylindrical body so that it can move forward and backward in the axial direction, and a measuring element follows the movement of the spindle and moves forward and backward in a direction perpendicular to the axis of the spindle. , a moving mechanism that moves the spindle in its axial direction to move the measuring head forward and backward in a direction orthogonal to the axis of the spindle, and a support that supports the measuring mechanism, and the measuring mechanism is connected to the inner diameter of the measuring hole. an advancing/retracting mechanism that moves the measuring mechanism forward and backward toward a measurement position; when the measuring mechanism is moved by the advancing/retracting mechanism, the measuring mechanism is aligned and supported on an axis specific to the device; and when an inner diameter of the measurement hole is measured, the support is released. and a self-aligning mechanism that aligns the measuring mechanism on the axis of the measuring hole when the measuring tip comes into contact with the inner surface of the measuring hole. (2) The self-aligning mechanism includes a tapered part provided on the outside of one end of the cylindrical body and a first bracket that is attached to the support of the advance/retreat mechanism and has a guide hole that fits into the tapered part and supports the measuring mechanism. a second bracket that is attached to the support of the advance/retreat mechanism and has a tapered protrusion provided above the end in addition to the cylindrical body; and a second bracket that is integrally attached to the measurement mechanism. 2. The inner diameter measuring device according to claim 1, further comprising a second centering portion made of a guide body having a hole that fits into the large diameter portion of the tapered projection. (3) The inner diameter measuring device according to claim 2, wherein the guide hole of the first bracket has a tapered side surface that comes into close contact with a tapered surface of a tapered part provided outside one end of the cylindrical body. . (4) The second bracket and the guide body of the second alignment part are formed to have a rotation stop structure that restrains the rotation of the cylindrical body about its axis. inner diameter measuring device. (5) The rotation prevention structure of the second alignment part is provided on a plurality of tapered protrusions on the second bracket and a guide body that fits into the large diameter portion of each of these tapered protrusions. The inner diameter measuring device according to claim 4, characterized in that the inner diameter measuring device comprises a plurality of holes. (6) A measuring mechanism in which a spindle is housed in a cylindrical body so as to be able to move forward and backward in the axial direction, and a measuring element follows the movement of the spindle and moves forward and backward in a direction perpendicular to the axis of the spindle. , a moving mechanism that moves the spindle in its axial direction and advances and retreats the measuring element in a direction perpendicular to the axis of the spindle; an advancing and retreating mechanism that advances and retreats the measuring mechanism toward an inner diameter measurement position of the measurement hole; a control unit that controls the operation of the mechanism and the advancing/retracting mechanism; a control unit that supports the measuring mechanism in alignment with an axis specific to the device when the advancing/retracting mechanism advances/retracts the measuring mechanism; an automatic alignment mechanism that aligns the measuring mechanism on the axis of the measuring hole when the support is released and the measuring head comes into contact with the inner surface of the measuring hole; means for controlling the operation of the advance/retreat mechanism based on the output of a sensor that detects an alignment support position of the self-aligning mechanism; and an output of a sensor that detects a support release position of the self-aligning mechanism with respect to the measuring mechanism. means for controlling the moving mechanism to start its operation based on the output of a sensor that detects an operation stop position of the advancing/retracting mechanism after the support of the self-aligning mechanism for the measuring mechanism is released; An inner diameter measuring device comprising: means for controlling the operation of the device to stop the operation of the device. (7) The inner diameter measuring device according to claim 6, wherein the advancing/retracting mechanism has a drive cylinder, and each sensor is provided along this drive cylinder.