JP3174232B2 - Actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator for moving a slider in an appropriate direction by a rotary drive unit, and more particularly, to a circuit for circulating a plurality of rolling elements for moving a slider without load. Regarding the improved one.

[0002]

2. Description of the Related Art A conventional actuator has, for example, the following configuration. First, there is a base, on which a ball screw as a feed screw is rotatably arranged. The ball screw is connected to an output shaft of a servomotor as a rotation drive unit, and is rotated in the same direction by rotating the servomotor in an appropriate direction. A ball nut as a feed nut is screwed into the ball screw, and a slider is fixed to the ball nut. When the ball screw is rotated in an appropriate direction by the servo motor, the ball nut and the slider move in an appropriate direction. Thus, various devices mounted on the slider move in the same direction.

The slider moves along a base. That is, a pair of guide portions is provided on the base side, and the slider is movably disposed between the pair of guide portions. A groove is formed in each of the pair of guide portions. On the other hand, a pair of grooves are also formed on the slider side so as to correspond to the above-mentioned grooves, and ball-unloaded circulating paths respectively connecting to the grooves are formed.
A plurality of balls as rolling elements are accommodated in the ball no-load circulation path and between the groove on the guide portion side and the groove on the slider side so as to roll and circulate. That is,
The slider moves along a pair of guide portions while rolling and circulating the plurality of balls.

[0004] Conventionally, the base and the slider are usually made of steel, and naturally the ball is also made of steel. On the other hand, in order to reduce the weight of the apparatus, the base and the main body of the slider are made of a light metal such as an aluminum alloy or a light alloy, and the base-side groove portion and the slider-side groove portion are A configuration in which a steel rail provided with a rolling element rolling groove is mounted and fixed has been considered (this is separately filed by the applicant of the present application).

[0005]

According to the above-mentioned conventional configuration, there are the following problems. That is, as described above, in order to reduce the weight of the apparatus, the base and the main body of the slider are made of a light metal such as an aluminum alloy or a light alloy, and the base-side groove portion and the slider-side groove portion are formed. To
When steel rails with rolling element rolling grooves are installed and fixed, obtain the mechanical strength required for steel balls to roll and circulate in the rolling element rolling grooves. However, since the circulation path formed in the main body of the slider is made of a light metal such as an aluminum alloy or a light alloy similarly to the main body, when the steel ball rolls and circulates, Has poor durability, and is expected to be worn, etc., and cannot maintain its soundness over a long period of time. In the case of a steel slider, when a hole is formed by machining, the ratio (L / D) of the hole diameter (D) to the hole depth (L) is large, and machining is difficult. In addition to the above problem, in order to realize smooth rolling and circulation of the ball, there is a processing difficulty that the inner surface of the hole must be finished smoothly. Further, when the main body of the slider is made of a light metal such as an aluminum alloy or a light alloy, a circulation path is formed by plastic working utilizing the characteristics of the extrusion processing. It has been extremely difficult to accurately form a circuit.

SUMMARY OF THE INVENTION The present invention has been made based on such a point, and it is an object of the present invention to provide a rolling element no-load circuit which can obtain a required durability without a difficult machining operation. An object of the present invention is to provide an actuator having:

[0007]

In order to achieve the above object, an actuator according to the present invention comprises a bottom wall and a pair of side walls erected from both right and left sides of the bottom wall and has a substantially U-shaped cross section. A base having at least a base-side rolling element rolling groove on the inner surface of each of the pair of side walls, and a base having at least a portion of the base-side rolling element rolling groove made of steel, and a base inside the base. A slider-side rolling element rolling groove is provided at a position corresponding to the pair of base-side rolling element rolling grooves movably disposed along the longitudinal direction, and at least a portion of the slider-side rolling element rolling groove is made of steel. A pair of insertion paths extending and formed in parallel with the slider-side rolling element rolling grooves between the pair of slider-side rolling element rolling grooves in the slider, and a pair of insertion paths in the pair of insertion paths. each arranged both ends inserted in a state where Mashimashi the gap A pair of cylinders made of a material having abrasion resistance to the rolling and circulation of the steel rolling elements, which are protruded and arranged by a predetermined amount, and one slider-side rolling element rolling groove adjacent to each other; A pair of return caps for positioning and holding one end of the cylindrical body protruded from the insertion path by the cylindrical body receiving portion while communicating with one cylindrical body at both ends, and the other slider side adjacent to each other A pair of return caps that allow the rolling element rolling groove and the other cylindrical body to communicate with each other at both ends thereof, and position and hold an end of the cylindrical body that is protruded and arranged from the insertion path by the cylindrical body receiving portion. It is characterized by having done. At this time, the base is made of light metal or light alloy, base side grooves are provided on the inner side surfaces of the pair of side walls, and steel rails provided with rolling element rolling grooves in the base side grooves are mounted and fixed respectively. It is possible to do. Further, the slider is made of a light metal or a light alloy, the slider side grooves are provided at positions corresponding to the pair of base side grooves, and the steel rails provided with the rolling element rolling grooves are mounted and fixed to the slider side grooves. It is possible. Further, a return cap, the rolling elements and having a return path having a radius (R ₅₎ to the rolling groove side, continuously return path by a predetermined amount than the radius (R ₅₎ to the cylinder-side small radius (R ₆₎ It is conceivable to have a straight portion having a length of (R ₅ -R ₆ ) as a cylinder receiving portion.

[0008]

That is, the rolling element no-load circulation path formed in the slider is constituted by a pair of cylindrical bodies made of a material having wear resistance, and these pair of cylindrical bodies are formed in the insertion path formed in the slider. Are inserted and arranged in a non-contact state, and are positioned and supported by a return cap. Thereby,
First, the abrasion resistance of the rolling element no-load circulation path in the slider is improved to prevent the rolling element from being damaged by rolling and circulation, and to maintain a stable function for a long period of time. Further, since the cylindrical body is not positioned with respect to the insertion path, but is positioned in relation to the return cap, the dimensional accuracy of the insertion path can be relaxed and processing and assembly can be facilitated. . In addition, the base and the slider have at least the rolling element rolling grooves made of steel. For example, the main body portion is made of a light metal such as aluminum alloy or a light alloy, and the rolling element rolling grooves are made of steel. It is conceivable to attach and fix the rail. Further, the return cap has a return path with a radius (R ₅ ) on the rolling element rolling groove side and a return path with a radius (R ₆ ) smaller by a predetermined amount than the radius (R ₅ ) on the cylindrical body side. It is conceivable that the rolling element has a smoother rolling / circulation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, there is a base 1, and this base 1
As shown in FIG. 4, the cross-sectional shape is substantially U-shaped, and comprises a bottom wall 1a and a pair of side walls 1b, 1c erected from both left and right sides of the bottom wall 1a. ing.
The base 1 is formed by extruding a light metal or light alloy, for example, an aluminum alloy, and its weight is reduced. The bottom wall 1a is hollow as shown in FIG. 4, and is designed so that its rigidity can be increased as well as its weight can be reduced. In the figure, hollow portions of the bottom wall 1a are indicated by reference numerals 3, 5, and 7, respectively. In addition, boundaries between the bottom wall 1a and the side walls 1b, 1c are inclined surfaces 1d, 1e, which are configured to reduce the concentration of stress in those portions. As the light metal or light alloy, for example, a magnesium alloy, a titanium alloy, or the like is assumed in addition to the aluminum alloy.

The base 1 is formed as a long object having a predetermined length as shown in FIGS. 1 and 2, and a housing 9 is connected to the right end in FIGS. 1 and 2. In the housing 9, a servo motor 1 as a rotation drive unit is provided.
1 are accommodated and arranged. The servo motor 11
Stator (stator) arranged on the inner peripheral side of housing 9
13 and a rotor (rotor) 15 rotatably accommodated inside the stator 13. The rotor 15 is fixed to an output shaft 17 integrated with a ball screw. A ball screw 19 is provided on the outer peripheral portion on the left side in FIGS. 1 and 2 of the output shaft 17.

The ball screw 19 has a ball nut 21.
Are screwed together with their rotation restricted, and a slider 23 is fixed to the ball nut 21. For example, various devices (not shown) are mounted on the slider 23. The slider 23 is also made of a light metal or light alloy,
For example, it is made of an aluminum alloy and has a configuration that greatly contributes to weight reduction of the device. The output shaft 17
Are bearing members 25 on both sides of the servomotor 11,
27, while being rotatably supported by bearing members 29, respectively, at the left end of the base 1 in FIGS.
It is rotatably supported by a bearing member 33. or,
On the right side of the bearing member 29 in FIG. 1, a detecting means 35 for detecting the rotation amount of the servomotor 11 is provided.
A cover 37 is covered and fixed to the right end of the housing 9 in FIGS. 1 and 2.

As shown in FIG. 5, base side grooves 41 and 43 are formed on the inner side surfaces of the pair of side walls 1b and 1c of the base 1, respectively. Each of the base-side grooves 41 and 43 has a rectangular cross-sectional shape. Steel base rails 45 and 47 are mounted and fixed to the base grooves 41 and 43, respectively. Rolling element rolling grooves 51 and 53 in which balls 49 as rolling elements roll are formed in these base side rails 45 and 47, respectively.

On the other hand, a pair of slider grooves 55 and 57 are formed on both left and right sides of the slider 23, respectively. The slider-side grooves 55 and 57 are formed at positions corresponding to the base-side grooves 41 and 43, respectively, and have the same shape, size, and the like as the base-side grooves 41 and 43. These slider-side grooves 55 and 57 have
Steel slider-side rails 59 and 61 are mounted and fixed respectively. Roller rolling grooves 63 and 65 are formed in the slider-side rails 59 and 61, respectively.

As shown in FIGS. 4 and 5, the slider 23 has cutouts 71 and 73 as insertion paths. These notches 71 and 73 are provided in the slider-side groove 5.
5 and 57, the bottom portion (the upper side in FIGS. 4 and 5) is formed in an arc shape. Cylindrical bodies 75 and 77 are inserted and arranged in the notches 71 and 73, respectively. As shown in FIG. 5, the outer diameters of the cylindrical bodies 75, 77 are smaller than the inner diameters of the notches 71, 73, and gaps 79, 81 are provided between the notches 71, 73.
Is formed. That is, the cylindrical bodies 75, 7
7 is inserted and arranged in the notches 71 and 73 in a non-contact state. The cylindrical bodies 75 and 77 are made of a stainless seamless steel pipe. Further, as shown in FIGS. 1 and 3, both ends of the cylindrical bodies 75 and 77 project and are disposed by a predetermined amount from both ends of the notches 71 and 73 on the slider 23 side.

The cylindrical body 75 corresponds to the rolling element rolling groove 63 of the slider side rail 59, and the cylindrical body 77 corresponds to the rolling element rolling groove 65 of the slider side rail 61. Therefore, looking at the cylindrical body 75 and the rolling element rolling groove 63 side, return caps 81 are attached to both ends of the cylindrical body 75 and the rolling element rolling groove 63, respectively, as shown in FIG. (Indicated by an imaginary line in FIG. 1),
The rolling element rolling groove 63 and the return caps 81 constitute a circulation path for the ball 49 to roll and circulate. The same applies to the cylindrical body 77 and the rolling element rolling groove 65 side.
1 and 81 (shown in FIG. 6)
The rolling element rolling groove 65 and the return caps 81 constitute a circulation path for the ball 49 to roll and circulate.

The return cap 81 includes, as shown in FIGS. 3 and 7, a return cap body 83 and a middle piece 8.
5 and a rubber seal 87. And
The return cap body 83 and the middle piece 85 constitute a return path for the ball 49, and through the return path,
The rolling element rolling groove 63 communicates with the cylindrical body 75 side. Although FIG. 7 shows only the configuration of the return cap 81 at one end of the cylindrical body 75, the same configuration is applied to the other end of the cylindrical body 77 and the other end of the cylindrical body 77. The return cap main body 83 has a shape as shown in FIGS. Also, as shown in FIG.
Return cap body 83, the arc portion 89 of radius R ₁
When it than comprise in succession and the arc portion 91 of the predetermined amount smaller radius R _2, by successive portions thereof arcuate portion 89 and 91, so as to constitute an outer wall of the return path. The right end in FIG. 8 on the side of the arc portion 89 is a scooping portion 93.

On the other hand, the middle piece 85 has a shape as shown in FIGS. Further, as shown in FIG. 8, middle piece 85 includes an arc portion 95 of radius R _3, comprise in succession and the arc portion 97 of the predetermined amount smaller radius R ₄ than they arc portion 95, With 97 consecutive parts,
The inner wall of the return path is constituted. A predetermined return path is constituted by the outer wall on the side of the return cap main body 83 and the inner wall on the side of the intermediate piece 85 described above. Looking at the rolling center trajectory of the ball 49 on this return road, the right side in FIG.
₅ and the left side has a smaller radius R
_{It is 6} . Looking at the left side in FIG. 8, the end of the return path is provided with a cylinder 75 (the same applies to the cylinder 77).
A cylindrical body receiving portion 99 for receiving the end portion is formed.

The center piece 85 and the return cap body 83
As shown in FIG. 7, first, a pair of grooves 101 and 103 are formed on the return cap main body 83 side. On the other hand, a pair of protrusions 105 and 107 are provided on the middle piece 85 side. By inserting the protrusions 105 and 107 into the grooves 101 and 103, the
5 is set at a predetermined position on the return cap main body 83 side. The positioning of the return cap main body 83 with respect to the end surface of the slider 23 is performed first.
Are protruding. On the other hand, positioning holes 113 and 115 are formed in the end surface on the slider 23 side. Therefore, the positioning projections 109 and 111 are aligned with the positioning holes 113 and 1.
By inserting the return cap 81 into the slider 15, the return cap 81 can be positioned with respect to the slider 23. still,
Although only the configuration of the return cap 81 at one end side of the cylindrical body 75 and the rolling element rolling groove 63 and its mounting structure have been described, the same applies to the configuration of the return cap 81 at the remaining three locations and its mounting structure. ing.

According to the present embodiment, the following effects can be obtained. First, in a case where the slider 23 is made of a light metal such as an aluminum alloy or a light alloy in order to reduce the weight of the apparatus, a circulation path is provided directly in the slider 23, and the ball 49 is rolled and circulated there. On the other hand, since the ball 49 was made of steel, there was a concern about wear of the circulation path. On the other hand, in the case of this embodiment, the notches 71 and 73 are formed in the slider 23, and the cylinders 75 and 77 made of stainless seamless steel pipe are inserted and inserted therein.
The ball 49 rolls in the cylinders 75 and 77
Since the circulation path is used to circulate, the concern of the wear of the circulation path of the slider 23 as described above has been eliminated, and a stable function can be maintained for a long period of time. or,
Unlike the case where the circulation path is directly processed and formed on the slider 23, processing and assembly are simplified without requiring high dimensional accuracy. For example, considering that a through hole for forming a circulation path is directly formed in the slider 23, such a through hole having a large ratio (L / D) between the hole depth (L) and the hole diameter (D) is straightened. In such a case, a difficult processing technique is required. On the other hand, in the case of this embodiment, the cylinders 75 and 77 are inserted into the notches 71 and 73 without restriction on the positional relationship, and the cylinder receivers of the return caps 81 and 81 are not inserted. A predetermined positioning is made by inserting the plugs into 99, 99. That is, since the desired positioning is not performed using the notches 71 and 73, the dimensional accuracy of the notches 71 and 73 does not need to be so high, and the processing becomes extremely simple. The cylindrical bodies 75 and 77 are made of a stainless steel seamless steel pipe as described above, and the inner surfaces thereof are smoothed by cold plastic working such as cold drawing. Since this cylinder is used, a straight portion of the smooth no-load circuit can be easily obtained. Looking at the configuration of the return cap 81 itself, the curvature of the return path is different, for example, between the rolling element rolling groove 63 side and the cylindrical body 75 side. Thereby, on the rolling element rolling groove 63 side, a rake-up portion 93 that is more gentle than when a straight line is connected between the rolling path and the no-load circulation path is provided, and on the cylindrical body 75 side, a straight line is formed. Parts, whereby smooth rolling and circulation of the ball 49 can be realized corresponding to the cylinders 75, 77 protruding from the notches 71, 73 by a predetermined amount. it can. This will be described with reference to FIG.
The smaller radius (R ₆ ) is located on the right side in FIG. 3, that is, on the side of the cylindrical body 75, and the end of the cylindrical body 75 is located at an extended arc of just 90 °. become. Due to this positional relationship, the tangent at the end of the curved portion coincides with the straight line, and as a result, a smooth trajectory can be obtained. or,
The larger radius (R ₅ ) is located on the left side in FIG. 3, and in this case also, the ends of the rolling element rolling grooves 51 and 63 are located at a position extended by 90 °. Become. Here, the radius (R ₅ ) is larger than the case where the straight section of the rolling path and the no-load circuit is constituted by a single curve, that is, (R ₅ + R ₆ ) / 2. A gradual shape can be obtained as compared with the case of one radius, and the ball 4
9 and the change rate of the running direction of the ball 49 when returning from the no-load circulation path to the running groove can be reduced, and as a result, a smooth operation can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. That is, in the first embodiment,
The insertion paths for inserting and arranging the cylinders 75 and 77 are provided as the notches 71 and 73. In the case of the second embodiment, the insertion paths are provided as the through holes 101 and 103. It is. Other configurations are the same as those in the first embodiment. Therefore, also in this embodiment, since the through holes 101 and 103 are arranged in a non-contact state, the positions and the shape accuracy of the through holes 101 and 103 may be coarse.
The same effects as in the first embodiment can be obtained.

The present invention is not limited to the above embodiments. First, as the material of the cylindrical bodies 75 and 77, there is, for example, self-lubricating plastics in addition to the stainless steel seamless steel pipe.
It suffices if it has desired mechanical strength and wear resistance during circulation and its inner surface is smooth. In the above embodiment, the base 1 and the main body of the slider 23 are made of a light metal such as an aluminum alloy or a light alloy, and a steel rail having rolling element rolling grooves is mounted and fixed. Although the present invention has been applied, the present invention may be applied to all steel-made steels in consideration of easiness of processing and positioning.

[0022]

As described in detail above, according to the actuator of the present invention, the mechanical strength of the rolling element no-load circulation path in the slider is increased to prevent the rolling element from being damaged due to rolling and circulation, and to be used for a long time. You can now maintain stable functions. In addition, there is a gap between the cylinder and the insertion path.
Rather than positioning it in the insertion path and positioning it with respect to the insertion path, positioning is performed in relation to the return cap, so that the dimensional accuracy of the insertion path can be relaxed and processing and assembly can be facilitated. it can. In the return cap, a return path having a radius (R ₅ ) is provided on the rolling element rolling groove side, and a return path having a radius (R ₆ ) smaller by a predetermined amount than the radius (R ₅ ) is continuously provided on the cylindrical body side. In the case where the rolling element is provided, the rolling and circulating of the rolling element can be made smoother corresponding to the cylinder projecting and arranged by a predetermined amount from the insertion path. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention, with a part of an actuator being cut away.

FIG. 2 is a side view showing the first embodiment of the present invention, in which a part of the actuator is cut away.

FIG. 3 is a view showing the first embodiment of the present invention, and is a partial plan view showing the configuration of the return cap and its vicinity.

FIG. 4 is a view showing the first embodiment of the present invention, and is a sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is a view showing a first embodiment of the present invention, and is a sectional view taken along line VV of FIG. 1;

FIG. 6 is a view showing a first embodiment of the present invention, and is a perspective view of a main part of an actuator.

FIG. 7 is a view showing the first embodiment of the present invention, and is an exploded perspective view showing a relationship between a return cap and a cylindrical body.

FIG. 8 is a view showing the first embodiment of the present invention, and is a cross-sectional view of the return cap.

FIG. 9 is a view showing the first embodiment of the present invention, and is a rear view showing the outer shape of the return cap main body.

FIG. 10 is a view showing the first embodiment of the present invention, and is a side view showing the outer shape of the return cap main body.

FIG. 11 is a view showing the first embodiment of the present invention, and is a side view showing an outer shape of the return cap main body.

FIG. 12 is a view showing the first embodiment of the present invention, and is a front view showing an inner shape of the return cap.

FIG. 13 is a view showing the first embodiment of the present invention, and is a cross-sectional view of the return cap.

FIG. 14 is a diagram showing the first embodiment of the present invention, and is a plan view of a middle piece.

FIG. 15 is a view showing the first embodiment of the present invention, and is a front view of the middle piece.

FIG. 16 is a view showing the first embodiment of the present invention, and is a front view of the middle piece.

FIG. 17 is a diagram showing the first embodiment of the present invention, and is a side view of the middle piece.

FIG. 18 is a view showing a second embodiment of the present invention and is a cross sectional view of an actuator.

[Description of sign]

 Reference Signs List 1 base 1a bottom wall 1b side wall 1c side wall 23 slider 41 base side groove 43 base side groove 45 base side rail 47 base side rail 49 ball (rolling element) 51 ball rolling groove 53 ball rolling groove 55 slider side groove 57 Slider-side groove 59 Slider-side rail 61 Slider-side rail 63 Ball rolling groove 65 Ball rolling groove 71 Notch (insertion path) 73 Notch (insertion path) 75 Cylindrical body 77 Cylindrical body 81 Return cap 83 Return cap body 85 Middle piece 87 seals

Continuation of the front page (56) References JP-A-61-136805 (JP, A) JP-A-50-6963 (JP, A) JP-A-5-27407 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) H02K 7/06 F16H 25/22

Claims (4)

(57) [Claims] 1. A bottom wall and a pair of side walls erected from both left and right sides of the bottom wall, the cross section of which is substantially U-shaped, and a base-side rolling element on each of inner surfaces of the pair of side walls. A base having a rolling groove and at least a portion of the base-side rolling element rolling groove made of steel; and a pair of the base sides which are arranged inside the base so as to be movable along a longitudinal direction of the base. A slider provided with a slider-side rolling element rolling groove at a position corresponding to each of the rolling element rolling grooves, wherein at least a portion of the slider-side rolling element rolling groove is made of steel; and a pair of the slider-side rolling element rolling elements in the slider. Between the grooves, extend parallel to the slider rolling element rolling groove.
A pair of formed insertion paths and a pair of insertion paths are disposed with a gap in the pair of insertion paths, and both ends thereof are protruded and arranged by a predetermined amount from the insertion path. A pair of cylindrical bodies made of a material having abrasion resistance and one of the slider-side rolling element rolling grooves and one cylindrical body adjacent to each other communicate with each other at both ends thereof. A pair of return caps for positioning and holding the ends of the more protruded / arranged cylinder, and connecting the other slider-side rolling element rolling groove and the other cylinder adjacent to each other at both ends thereof with a cylinder. An actuator, comprising: a pair of return caps for positioning and holding an end of a cylindrical body protruded and arranged from an insertion path by a body receiving portion. 2. The actuator according to claim 1, wherein the base is made of a light metal or a light alloy, a base-side groove is provided on each of inner surfaces of the pair of side walls, and a rolling element rolling groove is provided in the base-side groove. An actuator characterized by mounting and fixing steel rails. 3. The actuator according to claim 2, wherein the slider is made of a light metal or a light alloy, the slider side grooves are provided at positions corresponding to the pair of base side grooves, and the slider side grooves are provided with rolling element rolling grooves. An actuator characterized by mounting and fixing steel rails. 4. The actuator according to claim 3, wherein the return cap, which has a return path that radius (R ₅₎ and the center radius of the grooves in the rolling member rolling groove side, the radius (R ₅ to the cylinder-side ), A return path having a radius (R ₆ ) smaller by a predetermined amount than the center radius of the groove is continuously provided, and a straight portion having a length of (R ₅ -R ₆ ) is provided as the cylindrical body receiving portion. An actuator, characterized in that: