JP5544129B2 - Linear gauge - Google Patents

Description

  The present invention relates to a linear gauge that includes a shaft body that slides in the axial direction and measures the axial displacement of the shaft body.

  Conventionally, a linear gauge to which a ball spline structure is applied has been proposed (for example, see Patent Document 1). The linear gauge (linear scale) described in Patent Document 1 includes a spline shaft, an outer tube, a ball, and a cage that is disposed between the spline shaft and the outer tube and holds the ball. This suppresses the spline shaft from rotating about its axis while reducing the size of the linear scale in the width direction (described in paragraph [0012] of the specification of Patent Document 1).

JP 2004-1117060 A

  In the linear scale described in Patent Document 1, since a ball spline structure is adopted, a ball rolling groove is formed in the axial direction on the spline shaft. Therefore, foreign matter such as dust may enter the linear scale from the outside via the ball rolling groove. In that case, the accuracy of sensing deteriorates due to foreign matter adhering to the sensor and scale.

  In view of the circumstances as described above, an object of the present invention is to provide a linear gauge capable of preventing foreign matters such as dust from entering the linear gauge.

  Another object of the present invention is to provide a linear gauge capable of reducing the sliding resistance of a shaft body.

In order to achieve the above object, a linear gauge according to an embodiment of the present invention includes a shaft body, a scale, a main body, a sensor, and a packing material.
The shaft body has a spline groove.
The scale is provided on the shaft body.
The main body has an open end portion and a ball spline bearing structure, and the shaft body is supported by the ball spline bearing structure so that the shaft body slides through the opening of the open end portion.
The sensor is disposed in the body and reads the scale.
The packing material has a convex portion that contacts the spline groove, and is provided at the opening end of the main body.

  By adopting a ball spline for the linear gauge, foreign matter tends to enter through the spline groove of the shaft body. However, the foreign material can be prevented from entering when the convex portion of the packing material comes into contact with the spline groove. Further, for example, even when a foreign matter is accumulated on the spline groove in a portion exposed from the main body, the foreign matter can be removed so as to be scraped out from the spline groove by the convex portion.

  The contact between the convex portion of the packing material and the spline groove is a one-point contact. As a result, the frictional resistance between the convex part and the spline groove can be reduced compared to the case where the contact between the convex part and the spline groove is a multipoint contact, and as a result, the sliding resistance of the shaft body can be reduced. .

  The contact between the balls of the ball spline bearing structure of the main body and the spline grooves is a one-point contact. Thereby, compared with the case where the contact of a ball | bowl and a spline groove | channel is a multipoint contact, those frictional resistance can be reduced and the sliding resistance of a shaft body can be reduced.

  Further, the contact between the ball and a spline groove provided on the inner peripheral surface of the outer cylinder of the main body, which will be described later, can be a one-point contact. Thereby, the sliding resistance of a shaft body can be reduced.

  The main body includes an outer cylinder having an inner peripheral surface and an inner peripheral spline groove formed in the inner peripheral surface. In that case, the ball spline bearing structure of the main body includes a ball and a holder. The holder has a thickness smaller than the diameter of the ball, and holds the ball so that the ball is disposed between the spline groove of the shaft body and the inner peripheral spline groove of the outer cylinder.

  By providing the spline groove in the outer cylinder of the main body, it is possible to reduce the outer diameter of the outer cylinder at least in the portion where the ball spline bearing structure is provided, and to realize a reduction in the size of the linear gauge.

  The linear gauge further includes a cylinder mechanism provided in the main body for driving the shaft body by fluid pressure. In the present invention, since the space in the main body can be afforded, a cylinder mechanism can be provided in the main body. In particular, by sealing the inside of the main body with the packing material, the pressure loss of the fluid pressure when the cylinder mechanism is driven can be reduced, and the pressure transmission efficiency is improved. By providing the packing material, a synergistic effect of reducing the pressure loss is exhibited in addition to the effect of preventing the entry of foreign matter.

  The linear gauge further includes an installation portion formed by integral molding with the main body and provided with the sensor. Thereby, the number of parts of the linear gauge is reduced, and the linear gauge can be reduced in size. Also, the rigidity of the sensing area is improved.

  The body includes a first portion having a first thickness and a second portion having a second thickness that is greater than the first thickness. The user installs the linear gauge in a predetermined posture at a predetermined installation location by using a fixture for fastening the main body to fix it at the predetermined installation location. At this time, the second portion, which is a thick portion, is provided, whereby the rigidity of the second portion can be higher than that of the first portion. For example, even if the user tightens the second portion with a fixing tool, the user can solve the problem that the main body is deformed at the second portion.

  Further, for example, by adopting a ball spline for the linear gauge, it is not necessary to provide a separate rotation prevention mechanism such as a rotation prevention pin. Therefore, the space in the main body can be afforded, and the second portion having a large thickness can be formed in the main body without making the outer diameter of the main body larger than that of the conventional product.

  The second portion is provided closer to the opening end than the first portion. Thus, the installation state (fixed state) of the linear gauge can be stabilized by providing the second portion, which is a thick portion, as much as possible on the opening end side that is the side on which the shaft body operates.

A linear gauge according to another embodiment of the present invention includes a shaft body, a main body, a scale, a sensor, and a packing material.
The shaft body has a spline groove.
The main body has an open end portion and a ball spline bearing structure, and the shaft body is supported by the ball spline bearing structure so that the shaft body slides through the opening of the open end portion.
The scale is disposed in the main body.
The sensor is provided on the shaft body and reads the scale.
The packing material has a convex portion that contacts the spline groove, and is provided at the opening end of the main body.

  In the present invention, the scale is fixed in the main body, and the scale is read by a sensor that moves with the shaft. Also in the present invention, as in the case of the above-described invention, the protrusion of the packing material comes into contact with the spline groove, thereby preventing entry of the foreign matter. Further, for example, even when a foreign matter is accumulated on the spline groove in a portion exposed from the main body, the foreign matter can be removed so as to be scraped out from the spline groove by the convex portion.

  As described above, according to the present invention, it is possible to prevent foreign matters such as dust from entering the linear gauge.

It is sectional drawing which shows the linear gauge which concerns on one Embodiment of this invention. It is a perspective view which shows the ball spline structure mounted in this linear gauge. It is sectional drawing in the surface perpendicular | vertical to the axial direction. It is sectional drawing which shows the structure of the ball spline which concerns on a reference example. It is an expanded sectional view near the opening end of the outer cylinder. It is a perspective view which shows the state which the packing material removed from the opening edge part of an outer cylinder. It is a perspective view which shows a packing material. It is a front view which shows a packing material. It is a table | surface which shows the result which this inventor measured the sliding resistance of the shaft body by experiment. It is sectional drawing which shows the opening edge part vicinity of the linear gauge which concerns on other embodiment of this invention. It is sectional drawing which shows the linear gauge which concerns on another embodiment of this invention.

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

  FIG. 1 is a cross-sectional view showing a linear gauge according to an embodiment of the present invention.

  The linear gauge 100 includes a shaft body 3 and a main body 1 that supports the shaft body 3 so that the shaft body 3 slides in the axial direction that is the longitudinal direction of the shaft body 3 by the ball spline bearing structure 20. The main body 1 includes an outer cylinder 11 and a cover case 12 attached to the outer cylinder 11, and a ball spline bearing structure 20 is provided on the outer cylinder 11. The shaft body 3 is configured to slide so as to expand and contract with respect to the main body 1 via the open end 11 a of the outer cylinder 11 of the main body 1.

  A scale 4 is provided at one end of the shaft body 3. The scale 4 is disposed in the cover case 12 and has a scale base 4a and position information configured by patterning the scale base 4a with a fine pitch. A sensor 5 is disposed in the main body 1 at a position facing the scale base 4a. The sensor 5 is fixed to the main body 1, and is installed in an installation portion 11 b provided integrally with the outer cylinder 11, for example. For example, the installation part 11b is formed by integral molding with the outer cylinder 11. The gap between the detection surface of the sensor 5 and the surface of the scale table 4a is set to about 20 μm ± 5 μm. As the shaft body 3 slides, the sensor 5 reads the scale 4 (the position information). The sensor 5 is connected to an electric cable 8 via a flexible printed circuit board 6 and a connector 7.

  As the sensor 5, a magnetic type is typically used, but an optical type or an electrostatic type may be used.

  In the present embodiment, as described above, the installation portion 11 b of the sensor 5 is formed by integral molding with the outer cylinder 11 of the main body 1. Thereby, the number of parts of the linear gauge 100 decreases, and the linear gauge 100 can be reduced in size. Also, the rigidity of the sensing area is improved.

  Moreover, the shape of the cross section perpendicular | vertical to the axial direction of the scale stand 4a is D shape. Therefore, there is an advantage that the processing of the scale table 4a is easy and position information can be easily formed on the surface of the scale table 4a.

Further, in this embodiment, since the area between the detection surface of the sensor 5 and the surface of the scale table 4a, that is, the sensing area is substantially coaxially arranged with the shaft body 3, the Abbe error is reduced and detection is performed. Accuracy can be increased.

FIG. 2 is a perspective view showing a ball spline structure mounted on the linear gauge 100. FIG. 3 is a cross-sectional view taken along a plane perpendicular to the axial direction.

  The shaft body 3 has a spline groove 3a formed in the axial direction. As shown in FIG. 3, for example, a total of four spline grooves 3a are formed. For example, the angular interval of the arrangement of each spline groove 3a in the circumferential direction on the outer peripheral surface of the shaft body 3 is 60 to 70 ° for the upper two in FIG. 3, and the same for the lower two. Alternatively, these four spline grooves 3a may be provided at equal intervals in the circumferential direction at 90 °. Three spline grooves 3a may be provided, or two spline grooves 3a may be provided at intervals of 180 degrees. When the number of spline grooves 3a is an even number, such as two or four, as shown in FIG. 3, it becomes a vertical object (or left-right symmetry), so that the machining accuracy of the shaft body 3 when forming the spline grooves 3a is improved. To do.

  The ball spline bearing structure 20 includes balls 21 and a cylindrical holder 22 that holds these balls 21. The holder 22 is fixed to the inner peripheral surface of the outer cylinder 11. A plurality of through holes 22 a are formed in the holder 22 along the axial direction so as to correspond to the spline grooves 3 a of the shaft body 3. The balls 21 are rotatably disposed in the through holes 22a.

  An inner peripheral spline groove 11 c is also formed on the inner peripheral surface of the outer cylinder 11 at a position facing the spline groove 3 a of the shaft body 3. The thickness t1 of the holder 22 is smaller than the diameter t2 of the ball 21. Specifically, the diameter t2 of the ball 21 is such that the ball 21 is in contact with the spline groove 3a of the shaft body 3 and the inner peripheral spline groove 11c of the outer cylinder 11 in a state where the ball 21 is disposed in the through hole 22a. Is set to Typically, the wall thickness t1 of the holder 22 is 0.3 to 0.7 mm, and the diameter t2 of the ball 21 is 1 mm. The outer diameter of the outer cylinder 11 is 8 mm, for example.

  Thus, by forming the inner peripheral spline groove 11c on the inner peripheral surface of the outer cylinder 11 of the main body 1, at least the outer diameter of the outer cylinder 11 in the portion where the ball spline bearing structure 20 is provided can be reduced. . As a result, the linear gauge 100 can be reduced in size.

  As shown by a point A in FIG. 3, the contact between the ball 21 of the ball spline bearing structure 20 and the spline groove 3 a of the shaft body 3 is a one-point contact. The contact between the balls 21 and the inner peripheral spline groove 11c of the outer cylinder 11 is also a one-point contact (point B). That is, these balls 21 are in two-point contact. As a result, for example, as shown in FIG. 4, the sliding resistance of the shaft body 3 can be reduced as compared with a general ball spline four-point contact.

  Since the shaft body 3 moves more smoothly as the sliding resistance of the shaft body 3 is smaller, for example, the air pressure of the air cylinder mechanism 25 described later does not need to be large. Therefore, the driving energy of the air cylinder mechanism 25 can be reduced, and the amount of deformation of the measurement object when the contact 9 provided at the tip of the shaft body 3 contacts a measurement object (not shown) is minimized. Can be suppressed.

  The material of the ball spline configured by the shaft body 3 and the ball spline bearing structure 20 may be, for example, iron, stainless steel, other alloys, or resin.

  In this way, by adopting the ball spline for the linear gauge 100, the rotation of the shaft body 3 can be prevented even if torque is applied to the shaft body 3 around the axial direction of the shaft body 3. By preventing the shaft body 3 from rotating, the shaft body 3 can slide while the distance between the surface of the scale base 4a and the detection surface of the sensor 5 is maintained constant. Therefore, the detection accuracy of the sensor 5 does not decrease.

  A typical example of when torque is applied to the shaft body 3 around the axial direction is when the contactor 9 is attached or detached, such as when the user replaces the contactor 9. For example, when the distal end portion of the shaft body 3 and the contactor 9 are attached and detached with a screw, a large rotational force is applied to the shaft body 3 at the time of attachment / detachment.

  Further, in the linear gauge 100 according to the present embodiment, since a ball spline is employed, there is no need to provide a separate anti-rotation mechanism provided in, for example, a conventional linear gauge. Although not shown, this anti-rotation mechanism is composed of, for example, a long hole formed in a case or the like that is long in the axial direction, and a pin that is provided in the shaft body and engages with the long hole. However, in such a conventional anti-rotation mechanism, since the pin needs to slide in the longitudinal direction of the long hole in order to slide the shaft body, it is necessary to form a gap between the pin and the long hole. Therefore, the shaft body moves in the rotation direction, that is, rattles, which causes a decrease in detection accuracy of the sensor. In addition, such a rotation prevention mechanism requires the formation and processing of parts in a direction perpendicular to the axial direction, which requires manufacturing effort and cost. In addition, there is a problem that the rigidity of the linear gauge is low due to an increase in machining in the direction perpendicular to the axial direction.

  An air cylinder mechanism 25 for driving the shaft body 3 is provided on the side of the outer cylinder 11 opposite to the side where the ball spline bearing structure 20 is provided. In the air cylinder mechanism 25, a collar 26 fixed to the shaft body 3 is movably provided in the outer cylinder 11, and a spring 27 is connected between the collar 26 and the end 11 d of the outer cylinder 11. ing. By adopting the ball spline, the space in the main body 1 can be afforded as described above, so that an air cylinder mechanism integrated with the main body 1 can be used instead of providing a bellows or the like that expands and contracts by air as in the conventional product. 25 can be provided. Thereby, the linear gauge 100 can be reduced in size.

  FIG. 5 is an enlarged cross-sectional view of the vicinity of the open end 11 a of the outer cylinder 11. A packing material 10 is attached to the open end 11 a of the outer cylinder 11. FIG. 6 is a perspective view showing a state in which the packing material 10 is detached from the opening end portion 11 a of the outer cylinder 11. FIG. 7 is a perspective view showing the packing material 10, and FIG. 8 is a front view of the packing material 10.

  The packing material 10 includes a ring portion 10a, a plurality of inner peripheral convex portions 10b provided on the inner peripheral side of the ring portion 10a, and a plurality of outer peripheral convex portions 10c provided on the outer peripheral side of the ring portion 10a. Have The inner circumferential convex portion 10b of the ring portion 10a has a shape corresponding to the shape of the spline groove 3a of the shaft body 3, and is fitted into the spline groove 3a and is in contact with the spline groove 3a. The outer peripheral convex portion 10c has, for example, a shape longer in the axial direction than the inner peripheral convex portion 10b and has a shape corresponding to the shape of the inner peripheral spline groove 11c of the outer cylinder 11. The outer peripheral convex portion 10c is fitted in the inner peripheral spline groove 11c and is in contact with the inner peripheral spline groove 11c. As shown in FIG. 5, the outer peripheral convex portion 10 c is formed so as to extend from the ring portion 10 a to the inside of the outer cylinder 11, that is, toward the ball spline bearing structure 20 side.

  The inner peripheral convex portion 10b of the packing material 10 is provided on the ring portion 10a so as to be inclined with respect to a plane perpendicular to the axial direction. The direction of the inclination is a direction in which the end portion of the inner circumferential convex portion 10 b faces the tip portion of the shaft body 3.

  The inner circumferential convex portion 10b and the outer circumferential convex portion 10c are provided for the number of the spline grooves 3a and inner circumferential spline grooves 11c, for example, four each.

  As shown in FIG. 6, a flange portion 11 e is formed near the open end portion 11 a in the outer cylinder 11. The packing material 10 is positioned by the ring portion 10a of the packing material 10 coming into contact with the flange portion 11e. In order to secure the outer cylinder 11 and the packing material 10, a ring-shaped fixing member 15 is disposed adjacent to the packing material 10 as shown in FIG. 5. The fixing member 15 is disposed closer to the distal end side of the shaft body 3 than the position of the packing material 10.

  Examples of the material of the packing material 10 include, but are not limited to, nitrile rubber, silicon resin, or Duracon (POM).

  By adopting a ball spline for the linear gauge 100, foreign matter tends to enter through the spline groove 3 a of the shaft body 3. However, in this embodiment, when the inner peripheral side convex part 10b of the packing material 10 contacts the spline groove 3a, the entry of the foreign matter can be prevented. Further, for example, even when foreign matter is accumulated on the spline groove 3a exposed from the main body 1, for example, when the shaft body 3 is operated, the foreign matter is removed so as to be scraped out from the spline groove 3a by the inner circumferential convex portion 10b. be able to.

  In particular, the inner circumferential convex portion 10b of the packing material 10 is provided on the ring portion 10a so as to be inclined with respect to a plane perpendicular to the axial direction. Thereby, the approach to the main body 1 of a foreign material can be prevented more effectively.

  The inside of the main body 1 is sealed in an almost airtight state by the packing material 10 according to the present embodiment. Thereby, the pressure loss of the air in the area | region 28 (refer FIG. 1) in the cylinder at the time of the drive of the air cylinder mechanism 25 can be reduced, and the transmission efficiency of a pressure improves. In other words, the provision of the packing material 10 exhibits a synergistic effect of reducing the pressure loss in addition to the effect of preventing the entry of foreign matter.

  Similarly to the ball 21 of the ball spline bearing structure 20, the packing material 10 can be in a single point contact. That is, the contact between the inner peripheral convex portion 10b of the packing material 10 and the spline groove 3a of the shaft body 3 can be a one-point contact. Thereby, compared with the case where the contact between the inner peripheral side convex portion 10b and the spline groove 3a is a multipoint contact, the frictional resistance between the inner peripheral side convex portion 10b and the spline groove 3a can be reduced. The sliding resistance of the body 3 can be reduced.

  Further, the provision of the packing material 10 prevents the shaft body 3 from coming off from the main body 1.

  Next, the operation of the linear gauge 100 configured as described above will be described.

  In FIG. 1, a measurement object (not shown) is arranged on the left side of the linear gauge 100. In the air cylinder mechanism 25, when the air in the region 28 is depressurized, the collar 26 moves to the right in FIG. 1 against the elastic force of the spring 27, whereby the shaft body 3 is retracted into the main body 1. To move. On the other hand, when the reduced pressure state of the air in the region 28 is released, the shaft body 3 advances from the main body 1 by the return force of the spring 27 and returns to the original position. Thereby, the position and displacement amount of the measurement object are automatically measured.

  FIG. 9 is a table showing the results of experiments conducted by the inventor on the sliding resistance of the shaft body 3. As shown in this table, a value smaller than 0.07N or 0.06N is realized in all five times.

  FIG. 10 is a cross-sectional view showing the vicinity of the open end of a linear gauge according to another embodiment of the present invention.

  In the linear gauge 200 according to the present embodiment, a thick portion 61b as a second portion is provided on the outer end 61 of the main body 51 on the opening end 61a side through which the shaft body 3 is inserted. The part other than the thick part 61b of the outer cylinder 11 as the first part is thinner than the thick part 61b. The thickness of the thick part 61b can be set to 2 mm or more, for example.

  The user installs the linear gauge 200 in a predetermined posture at a predetermined installation location using a fixture for fastening the main body 51 to fix it at the predetermined installation location. At this time, the thick part 61b is provided in the outer cylinder 61, so that the rigidity of the thick part 61b can be increased more than other parts. Thereby, even if the user fastens the thick part 61b with the fixture, the problem such as the outer cylinder 61 being deformed by the thick part 61b can be solved.

  Further, the thick portion 61b to which the fixture is attached is provided as close as possible to the opening end 61a on the side on which the shaft body 3 operates, so that the linear gauge 200 is installed (fixed) when the shaft body 3 is operated. State) can be stabilized.

  By adopting a ball spline for the linear gauge 200, there is no need to provide a separate rotation prevention mechanism such as a rotation prevention pin. Therefore, the space in the main body 51 can be afforded, and the thick portion 61b can be formed in the main body 51 without making the outer diameter of the main body 51 larger than that of the conventional product.

  FIG. 11 is a cross-sectional view showing a linear gauge according to still another embodiment of the present invention.

  The linear gauge 300 according to the present embodiment is of an air extrusion type. For example, as compared with the linear gauge 300 according to the above-described embodiment, the collar 26 fixed to the shaft body 3 is disposed on the opposite side in the outer cylinder 11. That is, in the stationary state (non-operating state) shown in FIG. 10, the collar 26 is disposed at the end of the outer cylinder 11 opposite to the opening end 11a. In such a linear gauge 300, air is supplied into the region 28 of the main body 1 from the right side of the collar 26 in the drawing, and the collar 26 is pressed by the air pressure, so that the shaft against the elastic force of the spring 27 is provided. The body 3 slides to the left in the figure.

  The packing material 10 and the fixing member 15 are also attached to the open end 11a of the linear gauge 300, as in the above embodiment.

  The embodiment according to the present invention is not limited to the above-described embodiment, and various other embodiments are conceivable.

  In the above embodiment, the sensor 5 is fixedly arranged in the main body 1 and the scale 4 provided on the shaft body 3 moves. However, the scale 4 may be fixedly arranged in the main body 1 and the sensor 5 provided on the shaft body 3 may move.

  The inner circumferential convex portion 10b of the packing material 10 is inclined in a direction in which the end portion is directed toward the distal end portion side of the shaft body 3, but the inclination is not essential.

  In the above embodiment, the inner peripheral spline groove 11c is provided in the outer cylinder 11 of the main body 1. However, the inner peripheral spline groove 11c may be omitted. In this case, the outer diameter of the outer cylinder 11 is larger than that of the above embodiment.

  Instead of the air cylinder mechanism 25 according to the above embodiment, one using another fluid may be used. Examples of other fluids include inert gases such as helium, argon, and nitrogen. Alternatively, the other fluid is not limited to gas and may be a liquid such as oil.

  In the above embodiment, the air cylinder mechanism 25 and the like may be omitted. Moreover, the form etc. in which the installation part 11b is formed by integral molding with the outer cylinder 11 are not essential elements.

  In the above embodiment, the fixing member 15 is provided. However, the fixing member 15 may not be provided as long as the packing material 10 is securely fixed to the opening end portion 11a by the shape of the inner peripheral surface of the packing material 10 or the opening end portion 11a.

DESCRIPTION OF SYMBOLS 1,51 ... Main body 3 ... Shaft body 3a ... Spline groove 4 ... Scale 5 ... Sensor 10 ... Packing material 10b ... Inner peripheral side convex part 11, 61 ... Outer cylinder 11a, 61a ... Opening end part 11b ... Installation part 11c ... Inside Circumferential spline groove 20 ... Ball spline bearing structure 21 ... Ball 22 ... Holder 25 ... Air cylinder mechanism 61b ... Thick part 100, 200, 300 ... Linear gauge

Claims (9)

A shaft having a spline groove and a contact provided at the tip ;
A scale provided on the shaft body;
An opening end portion and a ball spline bearing structure, and the ball spline bearing structure supports the shaft body so that the shaft body slides through the opening of the opening end portion;
A sensor disposed in the body for reading the scale;
A ring portion, and a convex portion in contact with the spline grooves provided on the inner peripheral side of the ring portion, provided with a packing member disposed in said open end of said body,
The convex part of the packing material is a linear gauge provided so as to protrude from the ring part so as to incline toward a contact side of the shaft body with respect to a surface perpendicular to the axial direction . A shaft having a spline groove;
A scale provided on the shaft body;
An opening end portion and a ball spline bearing structure, and the ball spline bearing structure supports the shaft body so that the shaft body slides through the opening of the opening end portion;
A sensor disposed in the body for reading the scale;
It has a convex part that contacts the spline groove, and comprises a packing material provided at the opening end of the main body ,
The body is
A first portion having a first wall thickness;
A linear gauge having a second thickness greater than the first thickness and having a second portion provided closer to the opening end than the first portion . The linear gauge according to claim 1 or 2 ,
The contact between the convex part of the packing material and the spline groove is a linear gauge which is a one-point contact. The linear gauge according to claim 1 or 2 ,
A linear gauge in which contact between the ball of the ball spline bearing structure of the main body and the spline groove is a one-point contact. The linear gauge according to claim 1 or 2 ,
The main body has an outer cylinder having an inner peripheral surface and an inner peripheral spline groove formed on the inner peripheral surface,
The ball spline bearing structure of the main body is
With the ball,
A holder that holds the ball so that the ball is disposed between the spline groove of the shaft body and the inner peripheral spline groove of the outer cylinder. Linear gauge. The linear gauge according to claim 1 or 2 ,
A linear gauge provided in the main body and further comprising a cylinder mechanism for driving the shaft body by fluid pressure. The linear gauge according to claim 1 or 2 ,
A linear gauge formed by integral molding with the main body and further comprising an installation portion on which the sensor is installed. A shaft having a spline groove and a contact provided at the tip ;
An opening end portion and a ball spline bearing structure, and the ball spline bearing structure supports the shaft body so that the shaft body slides through the opening of the opening end portion;
A scale disposed within the body;
A sensor provided on the shaft body for reading the scale;
A ring portion, and a convex portion in contact with the spline grooves provided on the inner peripheral side of the ring portion, provided with a packing member disposed in said open end of said body,
The convex part of the packing material is a linear gauge provided so as to protrude from the ring part so as to incline toward a contact side of the shaft body with respect to a surface perpendicular to the axial direction . A shaft having a spline groove;
An opening end portion and a ball spline bearing structure, and the ball spline bearing structure supports the shaft body so that the shaft body slides through the opening of the opening end portion;
A scale disposed within the body;
A sensor provided on the shaft body for reading the scale;
It has a convex part that contacts the spline groove, and comprises a packing material provided at the opening end of the main body ,
The body is
A first portion having a first wall thickness;
A linear gauge having a second thickness greater than the first thickness and having a second portion provided closer to the opening end than the first portion .

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