JP2025156729A - Cylindrical workpiece dimension measuring device and positioning method for the device - Google Patents

Abstract

To provide a dimension measurement device having a simple structure.SOLUTION: A dimension measurement device that measures a diameter of a cylindrical workpiece (70), comprises: a pair of first contact elements (13A) that is arranged outside the cylindrical workpiece (70) and pressed against the cylindrical workpiece (70); and a pair of second contact elements (13B) that is arranged outside the cylindrical workpiece (70) separately from the first contact elements (13A) and pressed against the cylindrical workpiece (70) to measure a diameter different from that measured by the first contact elements (13A). When an axis orthogonal to a longitudinal center axis (70a) of the cylindrical workpiece (70) is defined as an orthogonal center axis (70b), a first center axis (11A) linking the pair of first contact elements (13A) and a second center axis (11B) linking the pair of second contact elements (13B) are arranged at positions line-symmetric with respect to the orthogonal center axis (70b). By pressing the cylindrical workpiece 70 by the pair of contact elements (13A, 13A) and the different pair of contact elements (13B, 13B), positioning of the cylindrical workpiece (70) becomes possible.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dimension measuring device for measuring the diameter of a cylindrical workpiece and a positioning method for the device.

[Terminology]
Over-ball diameter: Abbreviated as OBD. This is the diameter used to measure the tooth thickness of a gear.
Diameter of cylindrical workpiece: A general term for OBD, a diameter larger than OBD, and a diameter smaller than OBD.

[Conventional overball diameter measuring device]
Various dimension measuring devices for measuring the diameter of cylindrical workpieces have been put into practical use, one of which is an over-ball diameter measuring device (see, for example, Patent Document 1 (FIG. 1)).

When a gear is manufactured, the tooth thickness may be larger or smaller than the specified value. If the tooth thickness is larger or smaller than the specified value by more than the allowable value, the gear will be rejected.
In addition to directly measuring the gear tooth thickness with a caliper, a measurement method using the overball diameter is also known.

[Overball diameter measurement method]
Prepare two balls of a specified diameter. Insert the two balls into the gear tooth groove at a 180° pitch. If the tooth thickness is large, the tooth groove will be small and the balls will fit shallowly. If the tooth thickness is small, the tooth groove will be large and the balls will fit deep. Measure the outsides (or insides) of the two balls together. Based on this measurement, it can be determined whether the tooth thickness is within the specified value.

[Summary of the Prior Art]
In the over-ball diameter measuring device disclosed in Patent Document 1, a gear is attached to a main shaft (θ axis). The gear rotates around the θ axis. A pair of contacts (balls) advances and retreats along axes (XU axis, XL axis, hereinafter referred to as X axis for convenience) perpendicular to the θ axis. The pair of balls is movable along an orthogonal axis (Y axis) perpendicular to the θ axis and also perpendicular to the XU axis.

[Advantages of the prior art]
If the pair of balls were immobile along the Y axis, the balls may not smoothly fit into the gear tooth grooves because the gear is positioned by the main shaft (θ axis).
In this case, the technique of Patent Document 1 has the advantage that the ball moves along the Y axis, resulting in the ball smoothly entering the gear tooth grooves.

For convenience, the mechanism that moves the ball along the X-axis will be called the X-axis movement mechanism, and the mechanism that moves it along the Y-axis will be called the Y-axis movement mechanism.

The X-axis movement mechanism is mounted on the Y-axis movement mechanism, so if the Y-axis movement mechanism wobbles (or deforms), the X-axis movement mechanism will wobble (or deform) together.
Since the X-axis movement mechanism is a mechanism for moving the ball, it is undesirable for the position to change. Increasing the rigidity of the Y-axis movement mechanism is an effective countermeasure.

[Disadvantages of the prior art]
That is, in the technology of Patent Document 1, since an X-axis movement mechanism is added to a Y-axis movement mechanism, the over-ball diameter measurement device has a complex structure and is expensive. Furthermore, if the rigidity of the Y-axis movement mechanism is increased, the device becomes even more expensive and large in size.

In this type of dimension measuring device, the more complex the structure, the more likely it is to malfunction, and the higher the repair costs become. Such rising costs are a factor that hinders the widespread use of dimension measuring devices.
In order to promote the widespread use of dimension measuring devices, a dimension measuring device that is simple in structure and inexpensive is desired.

Patent No. 5860553

The objective of the present invention is to provide a dimension measuring device that is simple in structure and inexpensive.

After extensive research into solving this problem, the inventors came up with the idea of using two sets (two pairs) of contacts. This idea is explained based on Figures 1(a) and (b).

FIG. 1A is a diagram illustrating a comparative example.
When the outer periphery of the cylindrical workpiece 101 is pressed by a pair of contacts 102, 102, there is a possibility that the cylindrical workpiece 101 will move in a direction perpendicular to the central axis 104 (to the right or left in the figure) from the central axis 104 passing through the centers of the contacts 102, 102.
The technology that allows this movement is the technology disclosed in Patent Document 1.

A technique that replaces the technique disclosed in Patent Document 1 will be described with reference to FIG.
In Fig. 1(b), the central axis is given the reference symbol 11, and when the central axis 11 is to be distinguished as a first central axis and a second central axis, the first axis is prefixed with A and the second axis is prefixed with B, and the axes are referred to as the first central axis 11A and the second central axis 11B, respectively. The same applies to the other components below.

In Figure 1(b), the axis rotated clockwise from the Y axis by an angle θ is defined as the first central axis 11A, and a pair of first contactors 13A, 13A are arranged on this first central axis 11A. When the outer periphery of the cylindrical workpiece 70 is pressed by the pair of first contactors 13A, 13A, there is a possibility that the cylindrical workpiece 70 will move from the first central axis 11A in a direction perpendicular to the first central axis 11A.

An axis rotated counterclockwise from the Y axis by an angle θ is set as the second center axis 11B, and a pair of second contactors 13B, 13B is arranged on this second center axis 11B. When the outer periphery of the cylindrical workpiece 70 is pressed by the pair of second contactors 13B, 13B, there is a possibility that the cylindrical workpiece 70 will move from the second center axis 11B in a direction perpendicular to the second center axis 11B.
The pair of second contacts 13B, 13B presses different peripheral surfaces (surfaces with different diameters) from those of the first contacts 13A, 13A.

The movement in the direction perpendicular to the first central axis 11A and the movement in the direction perpendicular to the second central axis 11B cancel each other out, and the cylindrical workpiece 70 comes to rest when the balance is achieved. The longitudinal central axis 70a of the cylindrical workpiece 70 (the central axis extending from the front to the back of the drawing) comes to rest at a position displaced by δ from the origin 17 of the X-axis and Y-axis.
That is, the cylindrical workpiece 70 is positioned by the pair of first contacts 13A, 13A and the pair of second contacts 13B, 13B. In this state, the dimension measurement is carried out.

The invention completed based on the above findings is as follows.
The invention according to claim 1 is a dimension measuring device for a cylindrical workpiece that measures the diameter of the cylindrical workpiece,
a pair of first contactors arranged outside the cylindrical workpiece and pressed against the cylindrical workpiece; a pair of second contactors arranged outside the cylindrical workpiece separately from the first contactors and pressed against the cylindrical workpiece to measure a diameter different from that of the first contactors; and a control unit that calculates a distance between the pair of first contactors based on position information of the first contactors and calculates a distance between the pair of second contactors based on position information of the second contactors,
When an axis perpendicular to the longitudinal central axis of the cylindrical workpiece is defined as an orthogonal central axis,
The first central axis connecting the first contactors and the second central axis connecting the second contactors are arranged in line symmetry with respect to the orthogonal central axis.

In other words, as shown in FIG. 1(b), the device comprises a pair of first contactors 13A, 13A that are positioned outside the cylindrical workpiece 70 and pressed against the cylindrical workpiece 70, and a pair of second contactors 13B, 13B that are positioned outside the cylindrical workpiece 70 separately from the first contactors 13A, 13A and pressed against the cylindrical workpiece 70 to measure a diameter different from that of the first contactors 13A, 13A. When an axis perpendicular to the longitudinal center axis 70a of the cylindrical workpiece 70 is defined as an orthogonal center axis 70b, a first center axis 11A connecting the first contactors 13A, 13A and a second center axis 11B connecting the second contactors 13B, 13B are positioned in line-symmetrical positions with respect to the orthogonal center axis 70b.

The invention according to claim 2 is the cylindrical workpiece dimension measuring device according to claim 1,
the first contact and the second contact are each provided on a cylinder unit,
This cylinder unit is characterized by comprising: a long, thin cylinder that houses a piston; a piston rod that extends from the piston to the outside of the cylinder and has the first contact or the second contact at its tip; an air port that is provided in the cylinder and supplies compressed air that presses the surface of the piston away from the piston rod; a return spring that is provided in the cylinder and presses the surface of the piston facing the piston rod; and a position measurement mechanism that is housed in the cylinder and measures the position of the piston.

The invention according to claim 3 is the cylindrical workpiece dimension measuring device according to claim 1,
The cylindrical workpiece has external teeth, and of the three types of contactors, namely, a contactor that comes into contact with the tips of the external teeth to measure the large diameter, a contactor that is inserted into the tooth grooves of the external teeth to measure the overball diameter, and a contactor that comes into contact with the bottoms of the external teeth to measure the small diameter, one is the first contactor and the remaining one is the second contactor.

The invention according to claim 4 is the cylindrical workpiece dimension measuring device according to claim 1,
This device for measuring the dimensions of a cylindrical workpiece is characterized by having a turntable on which the cylindrical workpiece is placed and rotated, and also having a reference detection sensor located outside the turntable that detects the rotation reference of the cylindrical workpiece.

The invention according to claim 5 is the cylindrical workpiece dimension measuring device according to claim 4,
The turntable is characterized in that it is supported by an elevating mechanism.

The invention according to claim 6 is the cylindrical workpiece dimension measuring device according to claim 5,
When a first height from the top surface of the turntable and a second height higher than the first height are set within the height dimension of the cylindrical workpiece,
The control unit is characterized by performing a series of controls, including controlling the lifting mechanism so that the first height matches the first central axis, performing measurements at multiple locations while rotating the turntable at the first height, then raising the cylindrical workpiece so that the second height matches the first central axis, performing measurements at multiple locations while rotating the turntable at the second height, and then lowering the cylindrical workpiece so that the first height matches the first central axis.

The invention according to claim 7 is the cylindrical workpiece dimension measuring device according to claim 6,
When a master gauge is placed on the turntable and measurement values at multiple locations are obtained, the control unit corrects the measurement values of the cylindrical workpiece based on the obtained measurement values.

The invention according to claim 8 is the cylindrical workpiece dimension measuring device according to claim 3,
the first contactor is a contactor for measuring the overball diameter,
The control unit controls the insertion of the contact for measuring the overball diameter into the tooth groove at least once before measurement.

The invention according to claim 9 is the cylindrical workpiece dimension measuring device according to claim 7,
The control unit is characterized in that it displays a failure when the measured value deviates from the pass standard.

The invention according to claim 10 is the cylindrical workpiece dimension measuring device according to claim 7,
The control unit analyzes the acquired measurement value and displays a warning or an abnormality even if the measurement value is within the acceptable standard.

The invention according to claim 11 is the cylindrical workpiece dimension measuring device according to claim 6,
The control unit is characterized in that it controls to increase the number of measurement points when a command for precision measurement is received or periodically.

The invention according to claim 12 is the cylindrical workpiece dimension measuring device according to claim 4,
The turntable is driven by a rotation control motor,
The control unit controls the rotation angle and speed of the rotation control motor.

The invention according to claim 13 is the cylindrical workpiece dimension measuring device according to claim 5,
The lifting mechanism includes a nut fixed to a turntable, a screw shaft extending vertically and screwed into the nut, a support member for rotatably supporting the screw shaft, a large-diameter pulley fixed to the lower end of the screw shaft, a lifting control motor having a small-diameter pulley on its motor shaft, and a belt stretched between the large-diameter pulley and the small-diameter pulley,
The control unit controls the lifting control motor so that the cylindrical workpiece reaches a predetermined height.

The invention according to claim 14 is a positioning method for the cylindrical workpiece dimension measuring device according to claim 1, comprising:
the cylindrical workpiece dimension measuring device includes a center shaft that fits into a center hole of the cylindrical workpiece, a clamp and an L-shaped bracket that support the first contactor and the second contactor, respectively, a column that supports the L-shaped bracket, and a fixing bolt that fixes the L-shaped bracket to the column;
a step of preparing a boss that is detachably fitted onto the center shaft, a bar that passes through the boss and extends to the L-shaped bracket, and jig clamps that are the same shape as the clamps and that are detachably attached to both ends of the bar;
removing the clamp and the first and second contacts from the L-shaped bracket and removing the cylindrical workpiece from the center shaft;
loosening the fixing bolt to make the L-shaped bracket movable;
fitting the boss onto the center shaft;
Fixing a pair of L-shaped brackets to both ends of the bar via the jig clamp;
a step of tightening the fixing bolts in this fixed state to make the pair of L-shaped brackets immovable;
removing the jig clamp, the bar, and the boss;
a step of fixing the first contact to a pair of positioned L-shaped brackets via the clamp, and fixing the second contact to a pair of positioned L-shaped brackets via the clamp,
The present invention provides a positioning method for a cylindrical workpiece dimension measuring device, which positions the first contactor and the second contactor using an adjustment jig consisting of the boss, the bar, and the jig clamp.

In the invention of claim 1, two or more sets (two pairs) of contacts can be used to measure a wide variety of dimensions, including different diameters (e.g., over-ball diameter, large diameter, small diameter), using a single dimension measuring device. Furthermore, by arranging the two sets (two pairs) of contacts line-symmetrically with respect to an orthogonal central axis and pressing against the cylindrical workpiece, it is possible to position the cylindrical workpiece.

If a workpiece positioning device and a dimension measuring device were to be prepared separately, the equipment costs would be high. In contrast, in the present invention, the dimension measuring device also positions the workpiece, so the equipment costs can be reduced. Furthermore, since the dimension measuring device only has multiple pairs of contacts, the structure is simple and inexpensive.
That is, the present invention provides a dimension measuring device that is simple in structure and inexpensive.

In the invention of claim 2, the contacts are supported by an elongated cylinder unit. Because they are elongated, the contacts can be placed in narrow spaces. As a result, multiple contacts can be easily placed along the outer periphery of a cylindrical workpiece in the dimension measuring device, making it possible to measure multiple outer diameters at once.

In the invention according to claim 3, the cylindrical workpiece has external teeth, and the over-ball diameter and the large diameter, or the over-ball diameter and the small diameter, can be measured by the dimension measuring device.
Since the over-ball diameter is measured, the quality of cylindrical workpieces having tooth grooves can be improved.

In the invention of claim 4, the dimensions of the cylindrical workpiece are measured while it is being rotated on a turntable, making it possible to automatically measure the dimensions of multiple points on the outer periphery of the cylindrical workpiece.

In the invention of claim 5, the turntable is supported by an elevation mechanism, making it possible to measure dimensions at multiple locations at different heights. Therefore, for cylindrical workpieces such as clutch pulleys, which have long tooth grooves formed on the side walls created by bending the periphery of a disc, it is possible to evaluate the bending along the tooth grooves based on measurements at multiple locations at different heights, making it possible to detect defective products.

In the invention of claim 6, dimensional measurements are performed at multiple locations at a first height, then at multiple locations at a second height higher than the first height, and once the series of measurements is complete, the cylindrical workpiece is returned to its initial height. Dimensional measurements can be performed efficiently and quickly. Because measurements are completed in a short time, the dimension measuring device of the present invention can be applied to automated processing lines.

In the invention of claim 7, a correction value is determined using a master gauge and the measurement value is corrected using this correction value, thereby increasing the reliability of the measurement value.

In the invention of claim 8, the position of the cylindrical workpiece is corrected using the first contactor before measurement. This correction allows the ball of the first contactor to be inserted more reliably into the tooth groove. As a result, the reliability (measurement accuracy) of the over-ball diameter measurement is further improved.

In the invention of claim 9, a failure indication is displayed when the measured value falls outside the acceptance criteria. When applied to mass production, displaying a failure indication during mass production can prevent the outflow of defective products at an early stage.

The invention of claim 10 displays a warning or abnormality even if the measured value is within the acceptable standard, thereby preventing the release of defective products at an even earlier stage.

In the invention of claim 11, measurement accuracy can be confirmed by performing precise measurements as appropriate.

In the invention according to claim 12, the turntable is driven by a rotation control motor. The position of the cylindrical workpiece in the rotation direction is determined with high precision.

In the invention according to claim 13, the turntable is raised and lowered by an elevation control motor and a screw shaft. The vertical position of the cylindrical workpiece is determined with high precision.

According to the invention of claim 14, the positioning (particularly, axial alignment) of the contacts can be easily performed using an adjustment jig.
The adjustment jig used for this purpose is a simple jig consisting of a boss, a bar, and a jig clamp, and the jig is inexpensive and easy to procure.

1A and 1B are diagrams illustrating the basic principle of the present invention, where FIG. 1A is a diagram illustrating a comparative example, and FIG. 1B is a diagram illustrating an example. 1A and 1B are diagrams illustrating the basic structure of the contactor used in the present invention, where (a) is a cross-sectional view illustrating the structure of a cylinder unit having a contactor, (b) is an operational diagram of the first contactor, (c) is an operational diagram of the second and third contactors, and (d) is an operational diagram of the position measurement mechanism. 1 is a front view of a cylindrical workpiece dimension measuring device according to the present invention; FIG. 2 is a perspective view of an L-shaped bracket, a clamp, and a cylinder unit. 1 is a plan view of a cylindrical workpiece dimension measuring device according to the present invention; 1A is a perspective view of a cylindrical workpiece, FIG. 1B is an enlarged view of part b in FIG. 1A, FIG. 1C is a diagram illustrating the principle of the reference detection sensor, and FIG. 1D is a diagram illustrating the operation of the reference detection sensor. FIG. 2 is a block diagram of a control system. FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. 10A and 10B are diagrams illustrating the trends of measurement values. FIG. 10 is a flow chart illustrating a precision measurement mode performed by the control unit. 10A to 10D are diagrams illustrating the configuration and function of an adjustment jig. FIG. 10 is a flowchart illustrating a correction value determination mode performed by the control unit.

An embodiment of the present invention will be described below with reference to the attached drawings.

[Contact]
As shown in Fig. 2(a), the contactor 13 is provided on the cylinder unit 20. When the contactors 13 are further classified into first to third contactors, as explained above, the first contactor is designated by A, the second by B, and the third by C, and they are called the first contactor 13A, the second contactor 13B, and the third contactor 13C.

As shown in Figure 2(b), the first contactor 13A is inserted into the tooth groove of the external tooth 73 to measure the overball diameter. To this end, the first contactor 13A has a ball 14 of a predetermined outer diameter at its tip.

2C, the second contactor 13B is a contactor that measures the large diameter by contacting the tooth tips 74 of the external teeth 73. For this reason, the tip of the second contactor 13B is sharp.
The third contactor 13C is a contactor that measures the minor diameter by coming into contact with the tooth bottom 75 of the external tooth 73. For this purpose, the third contactor 13C also has a pointed tip. The pointed tip may be a truncated cone.

[Cylinder unit]
As shown in FIG. 2( a), the cylinder unit 20 comprises a long, thin cylinder 22 that houses the piston 21, a piston rod 23 that extends from the piston 21 to the outside of the cylinder 22 and has one of the first contact 13A, the second contact 13B, and the third contact 13C at its tip, an air port 24 that is provided in the cylinder 22 and supplies compressed air that presses the surface of the piston 21 away from the piston rod 23, a return spring 25 that is provided in the cylinder 22 and presses the surface of the piston 21 facing the piston rod 23, and a position measuring mechanism 30 that is housed in the cylinder 22 and measures the position of the piston 21 (i.e., the position of the contact 13).

Preferably, the air vent 24 is provided in the lid 26 that closes the opening of the cylinder 22. Furthermore, to determine the retraction limit of the piston 21, the lid 26 is opened and a cylindrical stopper 27 of a predetermined length is inserted.

For example, when a three-way air valve 28 is switched to supply compressed air from a compressed air source 29 to the air port 24, the piston 21 moves forward to compress the return spring 25, and the contact 13 moves forward together with the piston rod 23.
When the air valve 28 is switched to cut off the supply from the compressed air source 29 and open the air port 24 to the atmosphere, the return spring 25 causes the contact 13 to move backward together with the piston rod 23 and return to its original position (standby position).

Because the cylinder units 20 are long and narrow, a large number of cylinder units 20 can be efficiently arranged in a limited space.

[Position measurement mechanism]
The position measuring mechanism 30 housed in the cylinder unit 20 comprises, for example, a scale plate 31 extending from the piston 21 on the opposite side of the piston rod 23, and a light emitter 32 and a light receiver 33 arranged on either side of the scale plate 31.

As shown in Figure 2(d), the scale plate 31 has multiple slits 34, which are narrow, strip-shaped through-holes. When laser light is emitted from the light projector 32, some of the light passes through the slits 34 and reaches the light receiver 33. The light receiver 33 has a dense array of minute light-receiving elements, and the light-receiving elements are distinguished from the light-receiving elements, thereby recognizing the light-receiving lengths L1 and L2.

When the scale plate 31 moves forward or backward, the ratio of (slit 34 width/light receiving length L1) to (slit 34 width/light receiving length L2) changes. This change is monitored and the position of the scale plate 31 is calculated. As a result, the position of the contact 13 is measured by the position measurement mechanism 30.

[Cylindrical workpiece dimension measuring device]
As shown in FIG. 3, a dimensional measuring device 40 for a cylindrical workpiece (hereinafter referred to as the dimensional measuring device 40) includes a turntable 41 on which a cylindrical workpiece 70 is placed and rotated, a lifting mechanism 45 that supports the turntable 41, a clamp 42 and a stand 43 that support the contactor 13, and a base 44 that supports all of these together.

[Lifting mechanism]
The lifting mechanism 45 comprises, for example, a support 46 erected on the base 44, a screw shaft 48 attached vertically to the support 46 via a bearing 47, a nut 49 screwed to the screw shaft 48 and guided by the support 46 so that it can be raised and lowered, a shaft 51 extending upward from the nut 49, a large-diameter pulley 52 fixed to the lower end of the screw shaft 48, a lifting control motor 53 fixed to the support 46, a small-diameter pulley 54 attached to the motor shaft of the lifting control motor 53, and a belt 55 stretched between the small-diameter pulley 54 and the large-diameter pulley 52.

A stepping motor is preferably used as the lift control motor 53, but any type of control motor can be used as long as it is capable of fine control of the rotation angle and precise position control.

A longitudinal groove 56 is provided in the support member 46, and a key 57 is provided in the nut 49, and this key 57 fits into the longitudinal groove 56. The key 57 and the longitudinal groove 56 may be splines.
The lifting control motor 53 rotates the screw shaft 48 via the small diameter pulley 54, belt 55, and large diameter pulley 52. The presence of the key 57 prevents the nut 49 from rotating. Therefore, the nut 49 rises or falls. As a result, the turntable 41 rises or falls. In other words, the height of the turntable 41 is precisely controlled by the lifting control motor 53.

[Turntable]
The turntable 41 is rotatably supported on the shaft 51 via a bearing 58. A rotation control motor 61 is attached to the nut 49, and a small diameter gear 62 is attached to the motor shaft of the rotation control motor 61. The small diameter gear 62 meshes with a large diameter gear 63 that is integrally formed (or attached) to the bottom of the turntable 41.
The turntable 41 is rotated by a rotation control motor 61 via a small diameter gear 62 and a large diameter gear 63. The rotation control motor 61 precisely controls the rotation angle of the turntable 41.

A stepping motor is preferably used as the rotation control motor 61, but any type of control motor can be used as long as it is capable of fine control of the rotation angle and precise position control.

[stand]
The stand 43 that supports the contact 13 is made up of, for example, a column 64 that extends upward from the base 44, an L-shaped bracket 65 placed on the column 64, and a fixing bolt 66 that fixes the L-shaped bracket 65 to the column 64.
It is possible to omit the column 64 by making the vertical dimension of the L-shaped bracket 65 sufficiently large. However, this would lower the height of the fixing bolt 66, making it difficult to work with, so it is preferable to raise the height with the column 64 and position the fixing bolt 66 at a higher position.

[L-bracket and clamp]
As shown in Figure 4, the L-shaped bracket 65 is an L-shaped member consisting of a horizontal portion 65a and a vertical portion 65b extending upward from the horizontal portion 65a. The horizontal portion 65a has a horizontally extending elongated hole 65c. The vertical portion 65b has a female thread portion 65d.

The clamp 42 consists of a clamp body 42a, a retaining member 42b, a first bolt 42c, and a second bolt 42d. The clamp body 42a and retaining member 42b each have a groove 42e formed in them that corresponds to the cylinder unit 20.

Place the clamp body 42a on the cylinder unit 20. Next, place the retaining member 42b over the cylinder unit 20. Secure this retaining member 42b to the clamp body 42a with the first bolt 42c. The clamp 42 is now set on the cylinder unit 20.

Next, the clamp body 42a is attached to the L-shaped bracket 65 by screwing the second bolt 42d into the female thread portion 65d.
Next, the L-shaped bracket 65 is fixed to the column 64 shown in FIG.

As a result of the above, the contact 13 is fixed to the base 44 via the clamp 42 and the stand 43, as shown in FIG.
The configuration of the clamp 42 may be changed.

FIG. 5 is a plan view of the dimension measuring device.
As shown in FIG. 5, the first contactor 13A is fixed to a stand 43 by a clamp 42, and similarly, the second contactor 13B and the third contactor 13C are fixed.
The first contactors 13A, 13A are arranged on a first central axis 11A rotated clockwise by an angle θ from the Y axis, the second contactors 13B, 13B are arranged on a second central axis 11B rotated counterclockwise by an angle θ from the Y axis, and the third contactors 13C, 13C are arranged on a third central axis 11C on the X axis. In this example, the angle θ is 30°.

[Reference detection sensor]
In addition, a reference detection sensor 68 for detecting the rotation reference of the cylindrical workpiece is disposed outside the turntable 41 .

[Cylindrical workpiece]
6(a), a cylindrical workpiece 70 is made up of, for example, a peripheral wall 71, a bottom portion 72 that closes one end of the peripheral wall 71, and external teeth 73 formed on the outer surface of the peripheral wall 71. A central hole 72a is provided in the center of the bottom portion 72.
3, this center hole 72a is a hole with a gap added to the center shaft 41a extending upward from the turntable 41. Therefore, the cylindrical workpiece 70 can move horizontally by the amount of the gap.

As shown in FIG. 6B, the external teeth 73 have tooth tips 74 and tooth bottoms 75, and a small-diameter reference hole 76 is provided through the tooth bottoms 75.
As shown in FIG. 6A, the reference holes 76 are at different heights and comprise a first reference hole 76A, a second reference hole 76B, and a third reference hole 76C.

The first reference hole 76A is a hole corresponding to the "first height" described below, the second reference hole 76B set higher is a hole corresponding to the "second height", and the third reference hole 76C set higher is a hole corresponding to the "third height".

Although one first reference hole 76A is sufficient, considering that this first reference hole 76A will be detected by the reference detection sensor 68, it is desirable to provide multiple holes, such as holes at all tooth roots 75. The same applies to the second and third reference holes 76B and 76C. The more holes there are, the smaller the rotation angle required to complete reference detection, shortening the measurement time.

[Reference detection sensor]
As shown in FIG. 6C, the reference detection sensor 68 has, for example, a light emitting element 68b and a light receiving element 68c in a case 68a.
When a laser beam 68d emitted from the light-emitting element 68b is reflected by the tooth tip 74 or the tooth bottom 75, the reflected light reaches the light-receiving element 68c, which electrically recognizes the reflected light.

6(d), when the center of the reference detection sensor 68 coincides with the reference hole 76, the laser beam 68d enters the reference hole 76, and no reflected light is obtained. Even if a reflected light is obtained, it is a weak reflected light. At this time, the light receiving element 68c detects the reference hole 76.
Therefore, in FIG. 5, when the cylindrical workpiece 70 is rotated by the turntable 41 , the reference detection sensor 68 detects the reference hole 76 .

[Control unit]
As shown in FIG. 7, the control unit 80 obtains reference detection information from the reference detection sensor 68 .
The control unit 80 controls the rotation angle and speed of the rotation control motor 61 .
The control unit 80 controls the rotation angle of the lift control motor 53. By controlling the rotation angle of the lift control motor 53, the height position of the turntable is accurately controlled.

The control unit 80 controls the opening and closing of the air valve 28 to move the pair of first contactors 13A forward/backward to obtain the overball diameter measurement value, move the pair of second contactors 13B forward/backward to obtain the large diameter measurement value, and move the pair of third contactors 13C forward/backward to obtain the small diameter measurement value.
The control unit 80 compares the obtained measurement value with a reference value and makes a pass/fail determination.

Furthermore, the control unit 80 executes normal measurement mode, correction value determination mode, precision measurement mode, etc. based on the flow described below.

[Normal measurement mode]
As shown in FIG. 8, in step number (hereinafter abbreviated as ST) 01, a cylindrical workpiece is placed on a turntable by a robot (or manually).
The lifting mechanism is controlled to set the cylindrical workpiece to the "first height" (ST02), and the turntable is then rotated at a predetermined speed (ST03).
When the reference detection sensor detects the first reference hole (ST04), the turntable is stopped (ST05).

In ST06, the pair of first contacts (OBD measurement contacts) are moved forward and backward. This operation is generally performed once, but it may be repeated multiple times.
As shown in Fig. 2(b), the balls 14 enter the tooth grooves. If the cylindrical workpiece is out of phase with one another, this entry corrects the misalignment.

In ST07, the OBD is measured with the first contactor (see FIG. 2(b)), the large diameter is measured with the second contactor (see FIG. 2(c)), and the small diameter is measured with the third contactor (see FIG. 2(c)).
The obtained measured value is compared with a reference value for evaluation (ST08), and pass/fail is determined (ST09).
If the test is unsuccessful, a message indicating this is displayed (ST10), and the flow ends.

If the test passes, the turntable is rotated by a predetermined angle (for example, 120°) in ST11 and then stopped (ST12).
In ST13, the pair of first contacts (for OBD measurement) are moved forward and backward.
Then, measurements are carried out on the new location (ST14), the measured values are evaluated (ST15), a pass/fail decision is made (ST16), and if the result is unsuccessful, a failure is displayed (ST17).

In ST18, if measurement at the first height is to be continued, the process returns to ST11 and ST12 to ST17 are repeated.
This repetition provides multiple measurements at the first height.
If measurement at the first height is to be completed in ST18, the process proceeds to FIG.

In ST21 of FIG. 9, the lifting mechanism is controlled to set the cylindrical workpiece to the "second height." ST22 to ST36 of FIG. 9 are the same as ST03 to ST17 of FIG. 8, and therefore detailed explanations will be omitted.
That is, in FIG. 9, measurements are performed at the second height.
In ST37, if measurement at the second height is to be continued, the process returns to ST30 and ST31 to ST36 are repeated.
This repetition provides multiple measurements at the second height.
In ST37, if the measurement at the second height is to be completed, the process proceeds to FIG.

In ST41 of FIG. 10, the lifting mechanism is controlled to set the cylindrical workpiece to the "third height." ST42 to ST56 of FIG. 10 are the same as ST22 to ST36 of FIG. 9, so detailed explanations will be omitted.
That is, in FIG. 10, measurements are carried out at the third height.
In ST57, if measurement is to be continued at the third height, the process returns to ST50 and ST51 to ST56 are repeated.
This repetition provides multiple measurements at the third height.
If the measurement at the third height is completed in ST57, the cylindrical workpiece is removed from the turntable in ST58.
This completes the normal measurement mode.

Thus, three OBD measurements are obtained at the first elevation, three OBD measurements are obtained at the second elevation, and three OBD measurements are obtained at the third elevation, for a total of nine OBD measurements.
The first OBD measurement at the first height, the first OBD measurement at the second height, and the first OBD measurement at the third height are measurements at a common tooth space.

If the three OBD measurements in a common tooth space are the same (or nearly the same), the tooth space is straight along the vertical axis.
On the other hand, if there is a difference between the three OBD measurements for a common tooth space, an abnormality in the tooth space is suspected. Such an abnormality may include an inclined, curved, or meandering tooth space. If an abnormality is found, the cylindrical workpiece is rejected as a defective product.

In a strict sense, OBD is the dimension between the outer surfaces of the ball, but by measuring OBDs with different heights, it is possible to detect shape abnormalities in the tooth grooves.
This increases the added value of the dimension measuring device 40 according to the present invention.

The pass/fail judgment described in ST08 and ST09 in FIG. 8 may be made by comparing the measured value with a reference value, or by examining the tendency of changes in the measured value.
As shown in Figure 11(a), if a measurement value exceeds the reference value but is below the upper tolerance, the shaded area is the "difference" calculated as (measurement value - reference value).
The "differences" are arranged in chronological order in FIG. 11(b).

As shown in FIG. 11B, when the "difference" is on the rise and is expected to exceed the allowable value in the near future, it is recommended to issue a caution or warning.
That is, the control unit checks the trend of the acquired measurement values and displays a warning or abnormality even if the measurement values are within the acceptable standards.

By taking measures based on warning or abnormality indications before rejected products are produced, it is possible to prevent or reduce the occurrence of rejected products.

[Precise measurement mode]
As is well known, there are two types of inspection methods: 100% inspection and sampling inspection. 100% inspection is ideal, but it increases the inspection cost. Sampling inspection has the advantage of reducing the inspection cost.
The normal measurement mode described above corresponds to a sampling inspection.
The cylindrical workpiece 70 shown in FIG. 6A is a so-called press-formed product. That is, a die is set in a press machine, and a blank is subjected to plastic working with the die to obtain a press-formed product. During this process, the die gradually wears out. Therefore, the die is replaced periodically (for example, when a predetermined number of shots is reached).

When a mold is replaced, it is important to verify the accuracy of that mold. Therefore, it is desirable to perform precision measurements equivalent to a full inspection on the cylindrical workpiece 70 manufactured using the replaced mold.

In ST61 of FIG. 12, it is checked whether or not the precision measurement mode has been selected.
If the answer is no and the normal measurement mode is selected in ST62, the steps in FIGS. 8 to 10 are carried out (ST63).
When the precision measurement mode is selected in ST61, it is set in ST64 whether to measure N% of the number of external teeth. If N is 100%, 100% inspection is performed, and if N is 50%, 50% inspection is performed.
In ST65, N% is measured based on FIGS.

5, it is important to position (align) the first contactors 13A, 13A so that the first central axis 11A connecting the pair of first contactors 13A, 13A passes through the center (including almost the center) of the center shaft 41a. The same applies to the second contactor 13B and the third contactor 13C.
This positioning (axial alignment) work is performed very carefully and takes a long time, so it is desirable to shorten this work time.
An adjustment jig 85 capable of shortening the operation time is provided, and a method for positioning a dimension measuring device using this adjustment jig 85 will be described below.

[Adjustment jig]
FIG. 13(a) is a partial view of FIG.
In Fig. 13(a), the contact 13, the cylinder unit 20 and the clamp 42 are removed from the L-shaped bracket 65. The removed state is shown in Fig. 13(b).
As shown in FIG. 13( c), the adjustment jig 85 comprises a boss 86 that can be detachably fitted onto the center shaft 41 a, a bar 87 that passes through this boss 86 and extends to the L-shaped bracket 65, and jig clamps 88 that are fitted onto both ends of this bar 87.

The jig clamp 88 has the same structure as the clamp (FIG. 3, reference numeral 42), but the dimensions are different because the outer diameter of the cylinder unit 20 and the outer diameter of the bar 87 are different.
However, the center height ha of the jig clamp 88 shown in Fig. 13(d) is set to be the same as the center height ha of the clamp 42 shown in Fig. 13(a). This makes it possible to align the axis of the cylinder unit 20 (i.e., the contact 13) even when the jig clamp 88 is used instead of the clamp 42.

[Positioning method]
The first step in the positioning method is to prepare the dimension measuring device 40 shown in FIGS. 3 to 5 and the adjusting jig 85 shown in FIG. 13(c).
13A and 13B, the clamp 42 and the first contact 13A are removed from the L-shaped bracket 65. The second and third contacts 13B and 13C are also removed in the same manner.

As shown in Figure 3, if the cylindrical workpiece 70 is fitted onto the center shaft 41a, remove the cylindrical workpiece 70 from the center shaft 41a.

Next, in FIG. 13(b), the fixing bolt 66 is loosened to make the L-shaped bracket 65 movable.
13(d), a pair of L-shaped brackets 65 are fixed to both ends of the bar 87 via jig clamps 88. In this fixed state, the fixing bolts 66 are tightened to make the L-shaped brackets 65 immovable.

Next, in FIG. 13(d), the jig clamp 88, the bar 87 and the boss 86 are removed.
The state after removal is the same as that shown in FIG.
13(b), the first contactor 13A is fixed to the positioned L-shaped bracket 65 via the clamp 42. As a result, the state returns to that of FIG. 13(a), and the pair of first contactors 13A are accurately positioned. The second and third contactors 13B and 13C are also positioned in the same manner.

As described above, by positioning the first to third contactors 13A to 13C using the adjustment jig 85 consisting of the boss 86, bar 87, and jig clamp 88, the cylindrical workpiece dimension measuring device 40 can be positioned quickly and easily.

[Master Model]
The master model has the same appearance as the cylindrical workpiece 70 shown in Fig. 6(a). However, the master model is a machined product manufactured by cutting out a steel material. Machined products have significantly better dimensional accuracy than press-formed products.
Using such a master model, correction values can be determined.

[Correction value determination mode]
In ST71 of FIG. 14, the master model is placed on a turntable.
The lifting mechanism is controlled to set the cylindrical workpiece to a predetermined height (ST72), and the turntable is rotated at a predetermined speed (ST73).
When the reference detection sensor detects the reference hole (ST74), the turntable is stopped (ST75).

In ST76, the pair of first contacts (for OBD measurement) is moved forward and backward.
In ST77, the OBD is measured with the first contact, and the OBD correction value is determined according to the formula (OBD reference value - OBD measurement value = OBD correction value) (ST78).
In ST79, the large diameter is measured with the second contactor, and the large diameter correction value is determined by the formula (large diameter reference value - large diameter measured value = large diameter correction value) (ST80).
In ST81, the small diameter is measured with the third contactor, and the small diameter correction value is determined by the formula (small diameter reference value - small diameter measured value = small diameter correction value) (ST82).

The control unit measures the OBD and corrects the obtained measurement value with the OBD correction value. Similarly, the control unit measures the large diameter and corrects the obtained measurement value with the large diameter correction value, and measures the small diameter and corrects the obtained measurement value with the small diameter correction value (ST83).
As a result, the reliability of the measurement value can be further improved.

Note that while the dimension measuring device 40 of the present invention is suitable for cylindrical workpieces with external teeth, it can also be applied to cylindrical workpieces that do not have external teeth.

Furthermore, the structure of the cylindrical workpiece dimension measuring device 40 shown in FIG. 3 may be modified as appropriate.
Although three pairs of contacts are arranged in FIG. 5, two pairs of contacts or four or more pairs of contacts may be arranged.
Furthermore, the turntable may be configured to have an intermediate angle of 60° in addition to 120° to increase the number of measurement points.

The present invention is suitable for use in dimension measuring devices that measure the major and minor diameters on the outer periphery of cylindrical workpieces.

11A...first center shaft, 11B...second center shaft, 13...contactor, 13A...first contactor, 13B...second contactor, 14...ball, 20...cylinder unit, 21...piston, 22...cylinder, 23...piston rod, 24...air port, 25...return spring, 30...position measurement mechanism, 40...cylindrical workpiece dimension measurement device (dimension measurement device), 41...turntable, 41a...center shaft, 42...clamp, 45...lifting mechanism, 46...support material, 48 ...Screw shaft, 49...Nut, 52...Large diameter pulley, 53...Lifting control motor, 54...Small diameter pulley, 55...Belt, 61...Rotation control motor, 64...Column, 65...L-shaped bracket, 66...Fixing bolt, 68...Reference detection sensor, 70...Cylindrical workpiece, 70a...Longitudinal center axis, 70b...Orthogonal center axis, 72a...Center hole, 73...External teeth, 74...Tooth tip, 75...Tooth bottom, 80...Control unit, 85...Adjusting jig, 86...Boss, 87...Bar, 88...Jig clamp.

The movement in the direction perpendicular to the first central axis 11A and the movement in the direction perpendicular to the second central axis 11B cancel each other out, and the cylindrical workpiece 70 comes to rest when the balance is achieved. The longitudinal central axis 70a of the cylindrical workpiece 70 (the central axis extending from the front to the back of the drawing) comes to rest at a position displaced by δ from the origin 17 of the X-axis and Y-axis.
That is, the cylindrical workpiece 70 is positioned by the pair of first contacts 13A, 13A and the pair of second contacts 13B, 13B. In this state, the dimension measurement is carried out.

The invention according to claim 14 is a positioning method for the cylindrical workpiece dimension measuring device according to claim 1, comprising:
the cylindrical workpiece dimension measuring device includes a center shaft that fits into a center hole of the cylindrical workpiece, a clamp and an L-shaped bracket that support the first contactor and the second contactor, respectively, a column that supports the L-shaped bracket, and a fixing bolt that fixes the L-shaped bracket to the column;
a step of preparing a boss that is detachably fitted onto the center shaft, a bar that passes through the boss and extends to the L-shaped bracket, and jig clamps that are the same shape as the clamps and that are detachably attached to both ends of the bar;
removing the clamp and the first and second contacts from the L-shaped bracket and removing the cylindrical workpiece from the center shaft;
loosening the fixing bolt to make the L-shaped bracket movable;
fitting the boss onto the center shaft;
Fixing a pair of L-shaped brackets to both ends of the bar via the jig clamp;
a step of tightening the fixing bolts in this fixed state to make the pair of L-shaped brackets immovable;
removing the jig clamp, the bar, and the boss;
a step of fixing the first contactor to a pair of positioned L-shaped brackets via the clamp, and fixing the second contactor to a pair of positioned L-shaped brackets via the clamp,
The present invention provides a positioning method for a cylindrical workpiece dimension measuring device, which positions the first contactor and the second contactor using an adjustment jig consisting of the boss, the bar, and the jig clamp.

1A and 1B are diagrams illustrating the basic principle of the present invention, where FIG. 1A is a diagram illustrating a comparative example, and FIG. 1B is a diagram illustrating an example. 1A and 1B are diagrams illustrating the basic structure of the contactor used in the present invention, where (a) is a cross-sectional view illustrating the structure of a cylinder unit having a contactor, (b) is an operational diagram of the first contactor, (c) is an operational diagram of the second and third contactors, and (d) is an operational diagram of the position measurement mechanism. 1 is a front view of a cylindrical workpiece dimension measuring device according to the present invention; FIG. 2 is a perspective view of an L-shaped bracket, a clamp, and a cylinder unit. 1 is a plan view of a cylindrical workpiece dimension measuring device according to the present invention; 1A is a perspective view of a cylindrical workpiece, FIG. 1B is an enlarged view of part b in FIG. 1A, FIG. 1C is a diagram illustrating the principle of the reference detection sensor, and FIG. 1D is a diagram illustrating the operation of the reference detection sensor. FIG. 2 is a block diagram of a control system. FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. 10A and 10B are diagrams illustrating the trends of measurement values. FIG. 10 is a flow chart illustrating a precision measurement mode performed by the control unit. 10A to 10D are diagrams illustrating the configuration and function of an adjustment jig. FIG. 10 is a flowchart illustrating a correction value determination mode performed by the control unit.

[Cylindrical workpiece dimension measuring device]
As shown in Figure 3, the dimensional measuring device 40 for cylindrical workpieces (hereinafter referred to as the dimensional measuring device 40) includes a turntable 41 on which the cylindrical workpiece 70 is placed and rotated, a lifting mechanism 45 that supports the turntable 41, a clamp 42 and a stand 43 that support the contactor 13, and a base 44 that supports all of these together.

Claims (14)

A cylindrical workpiece dimension measuring device for measuring the diameter of a cylindrical workpiece,
a pair of first contactors arranged outside the cylindrical workpiece and pressed against the cylindrical workpiece; a pair of second contactors arranged outside the cylindrical workpiece separately from the first contactors and pressed against the cylindrical workpiece to measure a diameter different from that of the first contactors; and a control unit that calculates a distance between the pair of first contactors based on position information of the first contactors and calculates a distance between the pair of second contactors based on position information of the second contactors,
When an axis perpendicular to the longitudinal central axis of the cylindrical workpiece is defined as an orthogonal central axis,
A dimensional measuring device for a cylindrical workpiece, characterized in that a first central axis connecting the first contactors and a second central axis connecting the second contactors are arranged in a position symmetrical with respect to the orthogonal central axis. The cylindrical workpiece dimension measuring device according to claim 1,
the first contact and the second contact are each provided on a cylinder unit,
This cylinder unit is an apparatus for measuring the dimensions of a cylindrical workpiece, characterized in that it comprises a long, thin cylinder that houses a piston, a piston rod that extends from the piston to the outside of the cylinder and has the first contactor or the second contactor at its tip, an air port provided in the cylinder that supplies compressed air that presses the surface of the piston away from the piston rod, a return spring provided in the cylinder that presses the surface of the piston facing the piston rod, and a position measuring mechanism that is housed in the cylinder and measures the position of the piston. The cylindrical workpiece dimension measuring device according to claim 1,
The cylindrical workpiece has external teeth, and of the three types of contactors, namely a contactor that contacts the tips of the external teeth to measure the large diameter, a contactor that is inserted into the tooth grooves of the external teeth to measure the overball diameter, and a contactor that contacts the bottoms of the external teeth to measure the small diameter, one is the first contactor and the remaining one is the second contactor. The cylindrical workpiece dimension measuring device according to claim 1,
This device for measuring the dimensions of a cylindrical workpiece is characterized in that it comprises a turntable on which the cylindrical workpiece is placed and rotated, and also comprises a reference detection sensor that is arranged outside the turntable and detects the rotation reference of the cylindrical workpiece. The cylindrical workpiece dimension measuring device according to claim 4,
The device for measuring dimensions of a cylindrical workpiece is characterized in that the turntable is supported by a lifting mechanism. The cylindrical workpiece dimension measuring device according to claim 5,
When a first height from the top surface of the turntable and a second height higher than the first height are set within the height dimension of the cylindrical workpiece,
The control unit controls the lifting mechanism so that the first height matches the first center axis, performs measurements at multiple locations while rotating the turntable at the first height, then raises the cylindrical workpiece so that the second height matches the first center axis, performs measurements at multiple locations while rotating the turntable at the second height, and then lowers the cylindrical workpiece so that the first height matches the first center axis.This is an apparatus for measuring the dimensions of a cylindrical workpiece, characterized by performing a series of controls. The cylindrical workpiece dimension measuring device according to claim 6,
A dimensional measuring device for cylindrical workpieces, characterized in that when a master gauge is placed on the turntable and measurement values at multiple locations are obtained, the control unit corrects the measurement values of the cylindrical workpiece based on the obtained measurement values. The cylindrical workpiece dimension measuring device according to claim 3,
the first contactor is a contactor for measuring the overball diameter,
The device for measuring dimensions of a cylindrical workpiece is characterized in that the control unit controls the insertion of a contact for measuring the overball diameter into the tooth groove at least once before measurement. The cylindrical workpiece dimension measuring device according to claim 7,
The device for measuring dimensions of a cylindrical workpiece is characterized in that the control unit displays a failure when the measured value deviates from the pass standard. The cylindrical workpiece dimension measuring device according to claim 7,
The control unit analyzes the acquired measurement values and displays a warning or abnormality even if the measurement values are within the acceptable standards. The cylindrical workpiece dimension measuring device according to claim 6,
The device for measuring dimensions of a cylindrical workpiece is characterized in that the control unit controls the number of measurement points to be increased when a precision measurement command is received or periodically. The cylindrical workpiece dimension measuring device according to claim 4,
The turntable is driven by a rotation control motor,
The control unit controls the rotation angle and speed of the rotation control motor. The cylindrical workpiece dimension measuring device according to claim 5,
The lifting mechanism includes a nut fixed to a turntable, a screw shaft extending vertically and screwed into the nut, a support member for rotatably supporting the screw shaft, a large-diameter pulley fixed to the lower end of the screw shaft, a lifting control motor having a small-diameter pulley on its motor shaft, and a belt stretched between the large-diameter pulley and the small-diameter pulley,
The control unit controls the lifting control motor so that the cylindrical workpiece reaches a predetermined height. 2. A method for positioning a cylindrical workpiece dimension measuring device according to claim 1, comprising:
the cylindrical workpiece dimension measuring device includes a center shaft that fits into a center hole of the cylindrical workpiece, a clamp and an L-shaped bracket that support the first contactor and the second contactor, respectively, a column that supports the L-shaped bracket, and a fixing bolt that fixes the L-shaped bracket to the column;
a step of preparing a boss that is detachably fitted onto the center shaft, a bar that passes through the boss and extends to the L-shaped bracket, and jig clamps that are the same shape as the clamps and that are detachably attached to both ends of the bar;
removing the clamp and the first and second contacts from the L-shaped bracket and removing the cylindrical workpiece from the center shaft;
loosening the fixing bolt to make the L-shaped bracket movable;
fitting the boss onto the center shaft;
Fixing a pair of L-shaped brackets to both ends of the bar via the jig clamp;
a step of tightening the fixing bolts in this fixed state to make the pair of L-shaped brackets immovable;
removing the jig clamp, the bar, and the boss;
a step of fixing the first contact to a pair of positioned L-shaped brackets via the clamp, and fixing the second contact to a pair of positioned L-shaped brackets via the clamp,
A positioning method for a cylindrical workpiece dimension measuring device, which positions the first contactor and the second contactor using an adjustment jig consisting of the boss, the bar, and the jig clamp.