阅读说明：本技术 测量设备和轴承 (Measuring device and bearing ) 是由 林田秀二 辻胜三郎 于 2019-12-30 设计创作，主要内容包括：测量设备和轴承。测量设备(S)包括：外筒(22)；轴体(23),其能够在外筒(22)的内表面侧沿长度方向移动；多个轴承滚珠(24),其布置在外筒(22)的内表面与轴体(23)的外表面之间；以及测量部(3),其测量外筒(22)与轴体(23)之间的相对位置,并且第一区域(222)中的轴承滚珠(24)的第一密度比第二区域(223)中的轴承滚珠(24)的第二密度大,其中第一区域(222)从外筒(22)的一端开始并且具有比外筒(22)在长度方向上的全部长度短的第一长度(L1),第二区域(223)具有比外筒(22)的全部长度短的第二长度(L2),第二区域(223)以外筒(22)在长度方向上的中心位置为中心。(A measuring device (S) includes an outer cylinder (22), a shaft body (23) movable in a length direction on an inner surface side of the outer cylinder (22), a plurality of bearing balls (24) arranged between the inner surface of the outer cylinder (22) and an outer surface of the shaft body (23), and a measuring section (3) that measures a relative position between the outer cylinder (22) and the shaft body (23), and a first density of the bearing balls (24) in a first region (222) is greater than a second density of the bearing balls (24) in a second region (223), wherein the first region (222) starts from one end of the outer cylinder (22) and has a first length (L1) shorter than a total length of the outer cylinder (22) in the length direction, the second region (223) has a second length (L2) shorter than the total length of the outer cylinder (22), and the second region (223) is centered at a center position of the outer cylinder (22) in the length direction.)

1. A measurement apparatus, comprising:

an outer cylinder;

a shaft body movable in a longitudinal direction on an inner surface side of the outer cylinder;

a plurality of bearing balls disposed between an inner surface of the outer tub and an outer surface of the shaft body; and

a measuring portion that measures a relative position between the outer tub and the shaft body, wherein

A first density of the bearing balls in a first region starting from one end of the outer cylinder and having a first length shorter than an entire length of the outer cylinder in a length direction is greater than a second density of the bearing balls in a second region having a second length shorter than the entire length of the outer cylinder, the second region being centered on a central position of the outer cylinder in the length direction.

2. The measurement device of claim 1,

a third density of the bearing balls in a third region is greater than the second density, the third region starting from the other end of the outer tube and having a third length shorter than the entire length of the outer tube in the longitudinal direction.

3. The measurement device of claim 2,

the first density and the third density are the same.

4. A measuring device according to claim 2 or 3,

the bearing balls are not provided in the second region, and

the length in the lengthwise direction of the second region is greater than (i) the spacing between adjacent bearing balls in the first region and (ii) the spacing between adjacent bearing balls in the third region.

5. A measuring device according to claim 2 or 3,

the bearing balls are not provided in the second region, and

the length in the lengthwise direction of the second region is greater than at least one of (i) the spacing between adjacent bearing balls in the first region and (ii) the spacing between adjacent bearing balls in the third region.

6. The measurement device according to any one of claims 1 to 3,

the plurality of bearing balls are provided at positions symmetrical with respect to a center position in the longitudinal direction.

7. The measurement apparatus according to any one of claims 1 to 3, further comprising:

a holder including a plurality of holding portions for holding the plurality of bearing balls, wherein

The density of the plurality of holding portions that the holder has in the region corresponding to the first region is greater than the density of the plurality of holding portions that the holder has in the region corresponding to the second region.

8. The measurement device of claim 7,

a third density of the bearing balls in a third region which starts from the other end of the outer cylinder and has a third length shorter than the entire length of the outer cylinder in the longitudinal direction is greater than the second density, and

the density of the plurality of holding portions that the holder has in the region corresponding to the third region is greater than the density of the plurality of holding portions that the holder has in the region corresponding to the second region.

9. A bearing, comprising:

an outer cylinder;

a shaft body movable in a longitudinal direction on an inner surface side of the outer cylinder; and

a plurality of bearing balls disposed between an inner surface of the outer tub and an outer surface of the shaft body, wherein

A first density of the bearing balls in a first region starting from one end of the outer cylinder and having a first length shorter than an entire length of the outer cylinder in a length direction is greater than a second density of the bearing balls in a second region having a second length shorter than the entire length of the outer cylinder, the second region being centered on a central position of the outer cylinder in the length direction.

Technical Field

The invention relates to a measuring device and a bearing.

Background

Conventionally, a measuring apparatus having a spline bearing is used. Japanese patent application laid-open publication No. 2011-053046 discloses a linear meter having a ball spline bearing.

Disclosure of Invention

In the conventional linear meter, if an external force is applied to a shaft of a main shaft sliding through a bearing, the shaft is inclined in a length direction and accuracy of a measuring apparatus is lowered. Therefore, there is a need for a linear meter using bearings with little inclination of the spindle axis.

The present invention focuses on these aspects, and an object of the present invention is to provide a measuring apparatus in which a shaft of a main shaft sliding through a bearing is hardly inclined.

A first aspect of the present invention provides a measuring apparatus comprising: an outer cylinder; a shaft body movable in a longitudinal direction on an inner surface side of the outer cylinder; a plurality of bearing balls disposed between an inner surface of the outer tub and an outer surface of the shaft body; and a measuring section that measures a relative position between the outer cylinder and the shaft body, wherein a first density of the bearing balls in a first region starting from one end of the outer cylinder and having a first length shorter than an entire length of the outer cylinder in a length direction is greater than a second density of the bearing balls in a second region having a second length shorter than the entire length of the outer cylinder, the second region being centered on a central position of the outer cylinder in the length direction.

Further, a third density of the bearing balls in a third region starting from the other end of the outer cylinder and having a third length shorter than the entire length of the outer cylinder in the longitudinal direction may be greater than the second density. Further, the first density may be the same as the third density.

In addition, the bearing balls are not necessarily provided in the second region, and the length in the length direction of the second region may be larger than (i) the interval between the adjacent bearing balls in the first region and (ii) the interval between the adjacent bearing balls in the third region. In addition, the bearing balls are not necessarily provided in the second region, and the length in the length direction of the second region may be larger than at least one of (i) the interval between the adjacent bearing balls in the first region and (ii) the interval between the adjacent bearing balls in the third region.

Further, the plurality of bearing balls may be provided at positions symmetrical with respect to the center position in the longitudinal direction. Further, the measuring apparatus may further include a holder including a plurality of holding portions for holding the plurality of bearing balls, wherein a density of the plurality of holding portions which the holder has in a region corresponding to the first region may be greater than a density of the plurality of holding portions which the holder has in a region corresponding to the second region. In addition, a third density of the bearing balls in a third region starting from the other end of the outer cylinder and having a third length shorter than the entire length of the outer cylinder in the longitudinal direction may be greater than the second density, and the density of the plurality of retaining portions that the retainer has in a region corresponding to the third region may be greater than the density of the plurality of retaining portions that the retainer has in a region corresponding to the second region.

A second aspect of the present invention provides a bearing comprising: an outer cylinder; a shaft body movable in a longitudinal direction on an inner surface side of the outer cylinder; and a plurality of bearing balls arranged between an inner surface of the outer tube and an outer surface of the shaft body, wherein a first density of the bearing balls in a first region is greater than a second density of the bearing balls in a second region, wherein the first region starts from one end of the outer tube and has a first length shorter than a total length of the outer tube in a length direction, the second region has a second length shorter than the total length of the outer tube, and the second region is centered on a central position of the outer tube in the length direction.

According to the present invention, in the measuring apparatus, the shaft of the main shaft sliding through the bearing is hardly inclined.

Drawings

Fig. 1 shows a configuration of a measuring apparatus according to an embodiment.

Fig. 2 shows a configuration in the vicinity of the spline bearing according to this embodiment.

Fig. 3 shows an example of a configuration of a plurality of bearing balls.

Fig. 4 shows an example of the arrangement of a plurality of bearing balls as a comparative example.

Fig. 5 shows a structure of a spline bearing as a first modification.

Fig. 6 shows a structure of a spline bearing as a second modification.

Detailed Description

[ outline of the measuring apparatus S according to the present embodiment ]

Fig. 1 shows the configuration of a measuring apparatus S according to the present embodiment.

The measuring device S is for example a linear meter. The linear meter has the function of measuring length and is used, for example, to measure the geometry of an object. The measuring apparatus S includes a housing 1, a moving part 2, a measuring part 3, and a power supply part 4.

The housing 1 accommodates an electronic circuit, a scale, and the like of a measuring unit 3 described later in the measuring device S. When a force in the longitudinal direction is applied, the moving portion 2 moves in the longitudinal direction. The moving part 2 includes a spline bearing 21, an outer cylinder 22, and a shaft body 23.

The spline bearing 21 has a function of smoothly moving the shaft body 23 in the longitudinal direction with respect to the outer cylinder 22, and improves slidability. Further, the spline bearing 21 has a function of making it difficult for an external force or the like (for example, the weight of the shaft body 23 itself, the weight of a member attached to the shaft body 23, or an external force) to cause a tilt in the longitudinal direction when the shaft body 23 moves in the longitudinal direction. Details of the spline bearing 21 will be described later.

The outer cylinder 22 has a cylindrical shape, and a shaft body 23 movable in the longitudinal direction is provided inside the outer cylinder. The outer cartridge 22 is connected to the housing 1. Details of the outer cartridge 22 will be described later.

The shaft body 23 is movable in the longitudinal direction on the inner surface side of the outer cylinder 22. The shaft body 23 is, for example, a main shaft. For example, when the user measures the geometry of the object to be measured using the measuring apparatus S, in the case where the tip end of the shaft body 23 comes into contact with the outer surface of the object to be measured, the shaft body 23 moves in the longitudinal direction due to the irregularity of the object. Details of the shaft body 23 will be described later.

The measuring unit 3 has a function of measuring a relative position between the outer cylinder 22 and the shaft body 23 and outputting position information corresponding to the measured relative position. Specifically, the measuring unit 3 outputs position information indicating the position of the shaft body 23 with respect to the outer cylinder 22 when the shaft body 23 moves in the longitudinal direction of the outer cylinder 22.

The power supply section 4 has a function of supplying power to the measuring device S. For example, a receptacle into which a plug provided at a distal end of the power cord is inserted is formed in the power supply portion 4.

[ Structure of spline bearing 21 ]

Fig. 2 shows a configuration in the vicinity of the spline bearing 21 according to the present embodiment. Fig. 2 (a) shows a configuration in the vicinity of the spline bearing 21. Fig. 2 (b) is a sectional view of the spline bearing 21.

The spline bearing 21 includes an outer cylinder 22, a shaft body 23, a bearing ball 24, and a retainer 25. The outer cylinder 22 has a first groove 221 formed therein. A second groove 231 is formed in the shaft body 23.

The outer cylinder 22 has a plurality of first grooves 221. The first groove 221 extends on the inner surface of the outer cylinder 22 in the length direction of the outer cylinder 22. The first groove 221 accommodates some of the bearing balls 24. A plurality of first grooves 221 are formed adjacent to each other with a predetermined interval in the circumferential direction therebetween on the inner surface of the outer cylinder 22. The number of the first grooves 221 formed in the outer cylinder 22 is arbitrary.

The bearing balls 24 are disposed between the inner surface of the outer cylinder 22 and the outer surface of the shaft body 23. Each of the bearing balls 24 is spherical, and a portion of the bearing ball 24 contacts a first groove 221 formed in the inner surface of the outer cylinder 22. A portion of the bearing ball 24 different from a portion of the bearing ball 24 contacting the inner surface of the outer cylinder 22 contacts the second groove 231 formed in the outer surface of the shaft body 23. The bearing ball 24 is rotatable around the center of the bearing ball 24, and has a function of reducing sliding resistance of the shaft body 23 moving relative to the outer cylinder 22. The sliding resistance is resistance when the shaft body 23 slides in the longitudinal direction.

The shaft body 23 has a plurality of second grooves 231. The second groove 231 extends on the outer surface of the shaft body 23 in the longitudinal direction of the shaft body 23. The second groove 231 accommodates some of the bearing balls 24. The plurality of second grooves 231 are formed adjacent to each other with a predetermined interval in the circumferential direction therebetween on the outer surface of the shaft body 23. The number of the second grooves 231 formed in the shaft body 23 is arbitrary. The plurality of second grooves 231 are located at the same position in the circumferential direction of the shaft body 23 with respect to the plurality of first grooves 221.

For example, a part of each bearing ball 24 is located in the first groove 221 of the outer cylinder 22, and a part different from the part of the bearing ball 24 is located in the second groove 231 of the shaft body 23. In this way, a part of the bearing ball 24 is located in the first groove 221 of the outer cylinder 22, and a part different from the part of the bearing ball 24 is located in the second groove 231 of the shaft body 23, thereby restricting rotation of the shaft body 23 relative to the outer cylinder 22 in the circumferential direction.

[ arrangement of a plurality of bearing balls 24 ]

Fig. 3 shows an example of the configuration of the plurality of bearing balls 24 in the spline bearing 21 according to the embodiment. Fig. 4 shows an example of the arrangement of a plurality of bearing balls 24 in a spline bearing 51 as a comparative example. In the spline bearing 51, the plurality of bearing balls 24 are arranged uniformly.

Fig. 4 (b) shows a state in which an external force is applied to the shaft body 23 of the spline bearing 51. When an external force is applied to the spline bearing 51, the bearing balls 24 disposed at both ends of the plurality of bearing balls 24 are deformed more than the other bearing balls 24, and contribute to suppressing the inclination of the shaft body 23. That is, it is considered that the bearing balls 24 closer to the outer side of the row of the bearing balls 24 have a larger function of suppressing the inclination of the shaft body 23, and the bearing balls 24 in the vicinity of the center of the row of the bearing balls 24 have a smaller function of suppressing the inclination of the shaft body 23. Therefore, even if the bearing ball 24 near the center is a factor that increases the sliding resistance, it is considered that the bearing ball 24 near the center contributes to a small extent to suppressing the inclination of the shaft body 23.

On the other hand, in the spline bearing 21 according to the embodiment shown in fig. 3, the density of the bearing balls 24 near both ends of the outer cylinder 22 is higher than the density of the bearing balls 24 near the center. The density is the number of bearing balls 24 per unit length in the length direction of the outer cylinder 22. As a result, the sliding resistance of the spline bearing 21 is equal to that of the spline bearing 51 shown in fig. 4, and the shaft body 23 of the spline bearing 21 is hardly inclined as compared with the spline bearing 51 shown in fig. 4. Hereinafter, the spline bearing 21 will be described in detail.

As shown in fig. 3, the outer tub 22 has a first region 222, a second region 223, and a third region 224.

The first region 222 is a region starting from one end of the outer cylinder 22 and having a first length L1, the first length L1 being shorter than the entire length of the outer cylinder 22 in the longitudinal direction, the second region 223 is a region centered on the center position in the longitudinal direction of the outer cylinder 22 and having a second length L2, the second length L2 being shorter than the entire length of the outer cylinder 22, the third region 224 is a region starting from the other end of the outer cylinder 22 and having a third length L3, the third length L3 being shorter than the entire length of the outer cylinder 22 in the longitudinal direction.

The first density of bearing balls 24 in the first region 222 is greater than the second density of bearing balls 24 in the second region 223. Further, the third density of the bearing balls 24 in the third region 224 is greater than the second density. The density is the number of bearing balls 24 per unit length in the length direction of the outer cylinder 22. By arranging the bearing balls 24 in this manner, even if an external force is applied to the shaft body 23, the shaft body 23 is hardly inclined with respect to the longitudinal direction of the outer cylinder 22.

As shown in fig. 3, the plurality of bearing balls 24 are provided at positions symmetrical with respect to the center position in the longitudinal direction of the outer cylinder 22. Since the plurality of bearing balls 24 are arranged in this manner, the shaft body 23 is hardly inclined regardless of the position where external force or the like is applied to the shaft body 23.

In the example shown in fig. 3, the first density and the third density are the same, but the first density and the third density may be different. Furthermore, the bearing balls 24 need not be provided in the second region 223. In this case, the length in the lengthwise direction of the second region 223 is greater than (i) the spacing between adjacent bearing balls 24 in the first region 222 and (ii) the spacing between adjacent bearing balls 24 in the third region 224. Further, in this case, the length in the length direction of the second region 223 may be larger than at least one of (i) the interval between the adjacent bearing balls 24 in the first region 222 and (ii) the interval between the adjacent bearing balls 24 in the third region 224.

The retainer 25 has a function of retaining the plurality of bearing balls 24. The holder 25 has, for example, a cylindrical shape, the inner diameter of the holder 25 is slightly larger than the outer diameter of the shaft body 23, and the outer diameter of the holder 25 is smaller than the inner diameter of the outer cylinder 22. The holder 25 is located outside the shaft body 23 and inside the outer cylinder 22. The thickness of the retainer 25 is smaller than the diameter of the bearing ball 24. The holder 25 is movable in the longitudinal direction in accordance with the movement of the shaft body 23 in the longitudinal direction.

The holder 25 has a plurality of holding portions 251. Each of the holding portions 251 has a function of holding one bearing ball 24 and restricting the movement of the bearing ball 24. The number of the holding portions 251 is the same as the number of the bearing balls 24. A hole 252 for accommodating the bearing ball 24 may be formed in each of the holding portions 251. In this case, the diameter of the hole 252 is, for example, slightly larger than the diameter of the bearing ball 24 and the portion of the bearing ball 24 having the largest diameter is located within the hole 252.

The density of the plurality of holding portions 251 of the holder 25 in the region corresponding to the first region 222 is greater than the density of the plurality of holding portions 251 of the holder 25 in the region corresponding to the second region 223. Further, the density of the plurality of holding portions 251 that the holder 25 has in the region corresponding to the third region 224 may be greater than the density of the plurality of holding portions 251 that the holder 25 has in the region corresponding to the second region 223. With this configuration of the retainer 25, the density near both ends of the row of the bearing balls 24 is greater than the density near the center of the row of the bearing balls 24, and therefore the shaft body 23 is hardly inclined.

[ modification 1]

Fig. 5 shows a structure of a spline bearing 26 as a first modification. The spline bearing 26 differs from the spline bearing 21 shown in fig. 3 in that the density of the bearing balls 24 in the third region 224 is equal to the density of the bearing balls 24 in the second region 223, and the rest is the same. In this way, even if only the density of the bearing balls 24 in the first region 222 is greater than the density of the bearing balls 24 in the second region 223, the shaft body 23 of the spline bearing 26 can be made less prone to tilting than the shaft body of the spline bearing 51 shown in fig. 4.

[ modification 2]

Fig. 6 shows a structure of a spline bearing 27 as a second modification. In the spline bearing 27, the bearing balls 24 included in the second region 223 are removed from the spline bearing 26 shown in fig. 5, and the total number of the bearing balls 24 is smaller than the total number of the spline bearing 26 shown in fig. 5 and the total number of the spline bearing 51 shown in fig. 4. If the bearing balls 24 arranged in the second region 223 of the spline bearing 26 have a relatively small function of suppressing the inclination of the shaft body 23, the number of the bearing balls 24 can be reduced as in the case of the spline bearing 27, and the performance of suppressing the inclination of the shaft body 23 can be made larger than that of the spline bearing 51 while reducing the sliding resistance.

[ modification 3]

In the above description, the configuration of the measuring apparatus S having the spline bearing in which the bearing ball 24 is linearly arranged is exemplified, but the arrangement of the bearing ball 24 in the bearing of the measuring apparatus S is arbitrary. Further, the bearing of the measuring apparatus S is not limited to the spline bearing, and the configuration based on the same technical idea as the present embodiment can be applied to another type of bearing (such as a ball bush bearing).

[ Effect of the measuring apparatus S according to the present embodiment ]

A measuring instrument S according to the present embodiment includes an outer cylinder 22, a shaft body 23 movable in a longitudinal direction on an inner surface side of the outer cylinder 22, a plurality of bearing balls 24 provided between the inner surface of the outer cylinder 22 and an outer surface of the shaft body 23, and a measuring section 3 for measuring a relative position between the outer cylinder 22 and the shaft body 23, in the measuring instrument S, a first density of the bearing balls 24 in a first region 222 is larger than a second density of the bearing balls 24 in a second region 223, wherein the first region 222 starts from one end of the outer cylinder 22 and has a first length L1 shorter than a total length of the outer cylinder 22 in the longitudinal direction, and the second region 223 is centered on a center position of the outer cylinder 22 in the longitudinal direction and has a second length L2 shorter than the total length of the outer cylinder 22.

Therefore, when the measuring device S has the same bearing balls 24 as the conventional spline bearing, the shaft body 23 hardly tilts with the application of an external force. Further, if the number of bearing balls 24 is reduced as compared with the conventional spline bearing, the sliding resistance can be reduced and the shaft body 23 can be made to be hardly inclined. As described above, in the measuring apparatus S according to the present embodiment, since the sliding resistance and inclination of the shaft body 23 can be reduced, smooth operation and improvement in measurement accuracy can be achieved.

The invention has been explained on the basis of exemplary embodiments. The technical scope of the present invention is not limited to the scope described in the above embodiments, and various changes and modifications can be made within the scope of the present invention. For example, the specific embodiments of distribution and integration of the devices are not limited to the above embodiments, and all or part thereof can be configured with any units functionally or physically dispersed or integrated. Further, new exemplary embodiments produced by any combination thereof are included in the exemplary embodiments of the present invention. Further, the effects of the new exemplary embodiment brought about by the combination also have the effects of the original exemplary embodiment.

[ description of reference numerals ]

S … measuring equipment

A housing

Moving part

21 … spline bearing

22 … external cylinder

A first groove

A first region

A second area

A third region

Shaft body

A second groove

Bearing ball

A holder

251

Hole 252

26 … spline bearing

27 … spline bearing

3 … measurement part

A power supply part

A spline bearing