Bearing support structure and actuator

Abstract

To provide a bearing support structure and an actuator which can be constructed at low cost using a resin mold and can prevent slipping of a bearing.SOLUTION: A bearing support structure includes: a bearing holding part made of resin and formed in a projection shape, with a bearing housing recess part for holding a bearing being provided inside; a bearing housed and held in the bearing housing recess part; and an elastic holding member that is provided on an outer peripheral side of the bearing holding part and presses and holds the bearing through the bearing holding part. The bearing holding part is provided with a through hole for the elastic holding member which communicates with the bearing storage recess part. The elastic holding member includes a fixing projection part which projects into the bearing housing recess part through the through hole for the elastic holding member. The bearing is pressed and held via the fixing projection part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a bearing support structure for holding a shaft that drives a moving body, and an actuator, and in particular to an actuator that can be constructed inexpensively using a resin molded product and is designed to prevent bearing slippage. [Background technology]

[0002] A conventional bearing support structure is disclosed in, for example, Patent Document 1. The Cartesian coordinate assembly robot described in Patent Document 1 has a movable body movably installed on a casing via a guide rail. Ball bearings are press-fitted into both ends of the casing, and the ball screw shaft is rotatably supported by the ball bearings via a tapered shaft. The moving body is provided with a ball screw mechanism, and when the ball screw shaft is rotated, the moving body is moved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-135187 Summary of the Invention [Problem to be solved by the invention]

[0004] The above conventional configuration has the following problems. In a configuration such as the Cartesian coordinate type assembly robot described in Patent Document 1, the components that hold the ball bearings in the casing have traditionally been made of die-cast metal, for example, to ensure precision, but it is also possible to use resin molded components as cheaper components. However, in resin molded products, the fitting tolerances at the locations where the ball bearings are held are large, and there is a concern that the ball bearings may slip relative to the members of the casing that hold the ball bearings.

[0005] The present invention has been made based on these points, and its object is to provide a bearing support structure and actuator that can be constructed inexpensively using resin molded parts and that can prevent bearing slippage. [Means for solving the problem]

[0006] In order to achieve the above object, the bearing support structure according to claim 1 of the present invention comprises a bearing retaining portion made of resin, which is formed in a convex shape and has a bearing accommodating recess inside which a bearing is held, a bearing that is accommodated and held within the bearing accommodating recess, and an elastic retaining member that is installed on the outer periphery of the bearing retaining portion and passes through the bearing retaining portion to press and hold the bearing, wherein the bearing retaining portion has a through hole for elastic retaining member that communicates with the outer periphery and the inside of the bearing accommodating recess, and the elastic retaining member has a fixing protrusion that passes through the through hole for elastic retaining member and protrudes into the bearing accommodating recess, and the bearing is held by being pressed via the fixing protrusion. A bearing support structure according to claim 2 is the bearing support structure according to claim 1, characterized in that the through hole for the bearing holding member extends in the circumferential direction of the bearing holding portion. Furthermore, the bearing support structure according to claim 3 is characterized in that in the bearing support structure according to claim 1, a groove for an elastic retaining member into which the elastic retaining member engages is provided on the outer periphery of the bearing retaining portion. A bearing support structure according to claim 4 is the bearing support structure according to claim 1, characterized in that the elastic holding member is provided with a plurality of the fixing protrusions. A bearing support structure according to claim 5 is the bearing support structure according to claim 4, characterized in that the fixing protrusions are provided at equal intervals in the circumferential direction of the elastic holding member. A bearing support structure according to claim 6 is characterized in that in the bearing support structure according to claim 1, the fixing convex portion is formed so as to widen from the base side toward the tip side. Furthermore, a bearing support structure according to claim 7 is the bearing support structure according to claim 1, wherein the bearing comprises an outer ring held by the bearing holding portion, an inner ring rotatably installed within the outer ring, and rolling elements interposed between the outer ring and the inner ring, and the fixing convex portion presses against the outer ring. Furthermore, a bearing support structure according to claim 8 is the bearing support structure according to claim 1, characterized in that the shaft rotatably supported by the bearing is a screw shaft. An actuator according to claim 9 is characterized in that it is provided with the bearing support structure according to claims 1 to 8. [Effects of the Invention]

[0007] As described above, the bearing support structure according to claim 1 of the present invention comprises a bearing retaining portion that is made of resin and is formed in a convex shape, and that is provided with a bearing accommodating recess within which a bearing is held; a bearing that is accommodated and held within the bearing accommodating recess; and an elastic retaining member that is installed on the outer periphery of the bearing retaining portion and passes through the bearing retaining portion to press and hold the bearing, the bearing retaining portion is provided with an elastic retaining member through hole that connects the outer periphery with the inside of the bearing accommodating recess, and the elastic retaining member is provided with a fixing protrusion that passes through the elastic retaining member through hole and protrudes into the bearing accommodating recess, and the bearing is held by being pressed via the fixing protrusion, so that the structure can be constructed inexpensively using a resin molded product and slippage of the bearing can be prevented. According to a second aspect of the present invention, in the first aspect of the bearing support structure, the through-hole for the bearing holding member extends in the circumferential direction of the bearing holding portion, thereby effectively preventing the bearing from slipping. Furthermore, according to the bearing support structure of claim 3, in the bearing support structure of claim 1, a groove for an elastic retaining member into which the elastic retaining member engages is provided on the outer periphery of the bearing retaining portion, thereby preventing the elastic retaining member from falling off. According to a fourth aspect of the bearing support structure, in the first aspect of the bearing support structure, the elastic holding member is provided with a plurality of fixing protrusions, so that slippage of the bearing can be more effectively prevented. According to a fifth aspect of the present invention, in the bearing support structure of the fourth aspect, the fixing projections are provided at equal intervals in the circumferential direction of the elastic holding member, so that slippage of the bearing can be more effectively prevented. Furthermore, according to the bearing support structure of claim 6, in the bearing support structure of claim 1, the fixing convex portion is formed so as to widen from the base side toward the tip side, thereby preventing the elastic holding member from falling off. Furthermore, according to a bearing support structure of claim 7, in the bearing support structure of claim 1, the bearing is composed of an outer ring held by the bearing holding portion, an inner ring rotatably installed within the outer ring, and rolling elements interposed between the outer ring and the inner ring, and the fixing convex portion presses against the outer ring, thereby preventing the bearing from slipping while ensuring smooth operation. Furthermore, according to the bearing support structure of claim 8, in the bearing support structure of claim 1, the shaft rotatably supported by the bearing is a screw shaft, so even if an axial force is applied to the screw shaft, smooth operation can be ensured while preventing the bearing from slipping. Furthermore, according to the actuator of claim 9, the bearing support structure of claims 1 to 8 is provided, so that it can be constructed inexpensively using a resin molded product, bearing slippage can be prevented, and the actuator can be made lighter. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams showing an embodiment of the present invention, in which FIG. 1A is a cross-sectional view of an actuator provided with a bearing support structure, and FIG. 1B is an enlarged view of a portion Ib in FIG. 1A. [Figure 2]2(a) is a perspective view of the front cover and ball screw shaft of an actuator provided with a bearing support structure, with an enlarged view of the vicinity of the front end cover; and FIG. 2(b) is an exploded perspective view of the front cover and ball screw shaft of an actuator provided with a bearing support structure, with an enlarged view of the vicinity of the front end cover. [Figure 3] 3(a) and 3(b) are perspective views of the front cover as seen from the inside, the front cover as seen from the outside, the front cover as seen from the outside, the front cover as seen from the inside, and the front cover as seen from the outside. FIG. 3(c) is a plan view of the front cover, and FIG. 3(d) is a cross-sectional view taken along line IIId-IIId in FIG. 3(c). [Figure 4] 4(a) and 4(b) are views showing an embodiment of the present invention, in which FIG. 4(a) is a perspective view of an elastic holding member, FIG. 4(b) is a front view of the elastic holding member, and FIG. 4(c) is a cross-sectional view taken along line IVc-IVc of FIG. 4(b). DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will now be described with reference to FIGS. As shown in Figure 1, the actuator 1 according to this embodiment has a base 3. The base 3 extends in the front-rear direction (left-right direction in Figure 1(a)), and guide rails 5 are installed on both sides of the inner width direction (both sides in the direction of the page in Figure 1(a)). The guide rails 5 are formed with guide grooves 7, 7 that extend in the front-rear direction.

[0010] A front end cover 9 is attached to the front end of the base 3 (the left end in FIG. 1(a)). The front end cover 9 is made of resin and is provided with a cylindrical convex bearing holding portion 11 as shown in FIGS. The inside of the bearing holder 11 is the bearing accommodating recess 13. As shown in FIGS. As shown in FIG. 1(b), the bearing 15 has an outer ring 17, an inner ring 19 rotatably housed inside the outer ring 17, and a plurality of steel balls 20 as rolling elements installed so as to be able to roll between the outer ring 17 and the inner ring 19.

[0011] As shown in FIGS. 2 and 3, an annular groove 21 for an elastic holding member is provided on the outer peripheral surface of the bearing holding portion 11. 2 and 3, the bearing holder 11 is provided with an elastic retaining member through hole 23 that communicates with the outer periphery and the inside of the bearing accommodating recess 13. As shown in Fig. 3(c), the elastic retaining member through hole 23 extends in the circumferential direction (left-right direction in Fig. 3(c)) of the bearing holder 11. For example, as shown in Fig. 3(d), one elastic retaining member through hole 23 is provided at each of opposing positions on the upper and lower sides of the bearing holder 11 in Fig. 3(d).

[0012] As shown in FIGS. 1 to 3, an elastic holding member 25 made of, for example, rubber is engaged and installed in the groove 21 for the elastic holding member of the bearing holding portion 11. As shown in Fig. 4, the elastic retaining member 25 is provided with fixing protrusions 27 that penetrate the elastic retaining member through holes 23 of the bearing retaining portion 11 and protrude into the bearing accommodating recess 13. As shown in Fig. 4(b), the fixing protrusions 27 are provided one on each of the upper and lower positions facing each other in Fig. 4(b) in correspondence with the elastic retaining member through holes 23 of the bearing retaining portion 11. The bearing 15 is held by the outer ring 17 being pressed by the fixing projection 27 .

[0013] The fixing protrusions 27 are formed so as to widen from the base side (the upper side in FIG. 4(b) for the fixing protrusion 27 on the upper side in FIG. 4(b) and the lower side in FIG. 4(b) for the fixing protrusion 27 on the lower side in FIG. 4(b)) toward the tip side (the lower side in FIG. 4(b) for the fixing protrusion 27 on the upper side in FIG. 4(b) and the upper side in FIG. 4(b) for the fixing protrusion 27 on the lower side in FIG. 4(b)). Therefore, the fixing protrusions 27 are unlikely to come out when inserted into the elastic retaining member through-holes 23. Furthermore, the tip end surface 28 of the fixing projection 27 has a curved shape so as to fit the shape of the outer peripheral surface of the outer ring 17 of the bearing 15 when pressed against the outer ring 17 of the bearing 15 . The bearing holder 11, the elastic holder member 25, and the bearing 15 as described above constitute a bearing support structure 29.

[0014] A bearing holder 31 is installed at the rear end (right end in FIG. 1(a)) of the base 3. Two bearings 33 are installed inside the bearing holder 31. A ball screw shaft 35 is rotatably supported by the bearing 15 and the bearing 33. A spiral groove 36 is formed on the outer circumferential surface of the ball screw shaft 35.

[0015] As shown in Fig. 1, a slider 37 as a moving body is movably installed on the base 3. Slider-side guide rails (not shown) are provided on both sides of the slider 37 in the width direction (toward the surface of the page in Fig. 1(a)). Similar to the guide rail 5, the slider-side guide rails (not shown) are also provided with guide grooves (not shown).

[0016] End caps 39 are provided on both sides of the slider 37 in the front-to-rear direction (left-to-right direction in FIG. 1(a)). A return path (not shown) is provided in the end caps 39. In addition, an unloaded circulation path (not shown) is provided inside the slider 37.

[0017] A plurality of steel balls (not shown) roll and circulate in the space between the guide groove of the slider-side guide rail (not shown) and the guide groove 7 of the guide rail 5, in the return path (not shown) of the end cap 39, and in the unloaded circulation path (not shown). This allows the slider 37 to move relative to the base 3.

[0018] The ball screw shaft 35 is disposed so as to pass through the slider 37. A ball screw nut 41 is installed inside the slider 37. The ball screw shaft 35 passes through the ball screw nut 41, and there is a ball screw nut body 43 and end caps 45 installed on both sides of the ball screw nut body 43 in the front-to-rear direction (left-to-right direction in FIG. 1 ). A no-load circulation path (not shown) is provided in the ball screw nut body 43, and a return path (not shown) is formed in the end cap 45. A spiral groove 47 is formed on the inner peripheral surface of the ball screw nut body 43.

[0019] A plurality of steel balls 48 roll and circulate in the space between the spiral groove 36 of the ball screw shaft 35 and the spiral groove 47 of the ball screw nut body 43, in a return path (not shown) of the end cap 45, and in an unloaded circulation path (not shown) of the ball screw nut body 43.

[0020] As shown in Figure 1, a motor case 51 is installed at the rear end (right end in Figure 1(a)) of the bearing holder 31, and a motor 53 is installed inside the motor case 51. An output shaft 55 of the motor 53 is connected to the rear end (right end in Figure 1(a)) of the ball screw shaft 35 by a coupling mechanism 57. With this configuration, when the ball screw shaft 35 is rotated by the motor 53, the slider 37 is moved.

[0021] Next, the operation of this embodiment will be described. When the ball screw shaft 35 is rotated and driven by the motor 53, the slider 37 is moved in the front-rear direction (the left-right direction in FIG. 1).

[0022] The ball screw shaft 35 is rotatably supported by bearings 15 and 33, and the bearing 15 is held on the front end cover 9 by a bearing support structure 29. The bearing support structure 29 has an elastic holding member 25, and a pair of fixing protrusions 27 provided on the elastic holding member 25 presses the outer ring 17 of the bearing 15, preventing the bearing 15 from sliding relative to the front end cover 9 due to rotation of the ball screw shaft 35.

[0023] Next, the effects of this embodiment will be described. The bearing retaining portion 11 is formed in the front end cover 9 by resin molding, and the outer ring 17 of the bearing 15 accommodated and held in the bearing accommodating recess 13 of the bearing retaining portion 11 is held by the fixing protrusions 27 of the elastic retaining member 25 made of rubber mounted on the outer periphery of the bearing retaining portion 11 which penetrate through the elastic retaining member through hole 23 of the bearing retaining portion 11 and press against it. This allows the product to be constructed inexpensively using a resin molded product and prevents the bearing 15 from slipping relative to the front end cover 9. Furthermore, since the through-holes 23 for the elastic holding member extend in the circumferential direction of the bearing holding portion 11, slippage of the bearing can be effectively prevented. The tip surface 28 of the fixing protrusion 27 has a curved shape so as to follow the shape of the outer peripheral surface of the outer ring 17 of the bearing 15 when pressed against the outer ring 17 of the bearing 15, thereby effectively preventing the bearing from slipping.

[0024] Furthermore, the bearing holder 11 is provided on its outer periphery with an elastic holding member groove 21 into which the elastic holding member 25 is engaged, thereby preventing the elastic holding member 25 from falling off. Furthermore, since the elastic holding member 25 is provided with a plurality of fixing projections 27, it is possible to more effectively prevent the bearing from slipping. Furthermore, since the fixing projections 27 are provided at equal intervals in the circumferential direction of the elastic holding member 25, slippage of the bearing can be prevented more effectively. Furthermore, since the fixing projection 27 is formed so as to widen from the base side toward the tip side, it is possible to prevent the elastic holding member 25 from falling off.

[0025] Furthermore, the bearing 15 is composed of an outer ring 17 held by the bearing holder 11, an inner ring 19 rotatably installed within the outer ring 17, and steel balls 20 as rolling elements interposed between the outer ring 17 and the inner ring 19, and the fixing protrusions 27 press against the outer ring 17, thereby preventing the bearing 15 from slipping while ensuring smooth operation. Furthermore, since the ball screw shaft 35 is supported by the bearing 15, even if an axial force is applied to the ball screw shaft 35, smooth operation can be ensured and the bearing 15 can be prevented from slipping relative to the front end cover 9. Furthermore, since the front end cover 9 is made of resin and is used for the bearing support structure 29, the weight of the actuator 1 can be reduced.

[0026] The present invention is not limited to the above embodiment. The number of fixing protrusions of the elastic retainer and the number of elastic retainer through holes of the bearing holder may vary as long as they are provided in plural numbers. Furthermore, regardless of the number of fixing protrusions or elastic retainer through holes, they may be provided at equal intervals in the circumferential direction of the elastic retainer. The illustrated configuration is merely an example, and various other cases are possible. [Industrial Applicability]

[0027] The present invention relates to a bearing support structure and actuator that holds a shaft that drives a moving body, and in particular to one that can be constructed inexpensively using resin molded parts and is designed to prevent bearing slippage, and is suitable, for example, for a bearing support structure for an actuator used in an industrial robot. [Explanation of symbols]

[0028] 1 actuator 11 Bearing holder 13 Bearing receiving recess 15 Bearings 17 Outer ring 19 Inner Circle 20 Steel ball (rolling element) 21 Groove for elastic retaining member 23 Elastic retaining member through hole 25 Elastic retaining member 27 Fixing protrusion 28 Tip surface 29 Bearing support structure 35 Ball screw shaft (screw shaft)

Claims

1. a bearing holding portion made of resin and formed in a convex shape, the bearing holding portion having a bearing accommodating recess provided inside the bearing holding portion; a bearing accommodated and held in the bearing accommodating recess; an elastic holding member that is installed on the outer periphery of the bearing holding portion, penetrates the bearing holding portion, and presses and holds the bearing; Equipped with The bearing holder is provided with an elastic holding member through hole that communicates the outer periphery with the inside of the bearing accommodating recess, The elastic holding member is provided with a fixing protrusion that penetrates the elastic holding member through-hole and protrudes into the bearing accommodating recess, A bearing support structure characterized in that the bearing is pressed and held via the fixing protrusion.

2. The bearing support structure according to claim 1, The bearing support structure is characterized in that the through hole for the bearing holding member extends in the circumferential direction of the bearing holding portion.

3. The bearing support structure according to claim 1, A bearing support structure characterized in that an elastic holding member groove, into which the elastic holding member is engaged, is provided on the outer periphery of the bearing holding portion.

4. The bearing support structure according to claim 1, The bearing support structure is characterized in that the elastic holding member is provided with a plurality of the fixing protrusions.

5. The bearing support structure according to claim 4, The bearing support structure is characterized in that the fixing protrusions are provided at equal intervals in the circumferential direction of the elastic holding member.

6. The bearing support structure according to claim 1, A bearing support structure characterized in that the fixing protrusion is formed so as to widen from the base side toward the tip side.

7. The bearing support structure according to claim 1, the bearing comprises an outer ring held by the bearing holder, an inner ring rotatably installed within the outer ring, and rolling elements interposed between the outer ring and the inner ring, The fixing protrusion presses the outer ring.

8. The bearing support structure according to claim 1, A bearing support structure characterized in that the shaft rotatably supported by the bearing is a screw shaft.

9. An actuator provided with the bearing support structure according to any one of claims 1 to 8.

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