WO2012144371A1 - Linear motion guide mechanism - Google Patents

Abstract

A linear motion guide mechanism (1) used to guide a member which linearly moves forward and backward. The linear motion mechanism (1) is provided with a housing (2), a screw shaft (3) which is supported by the housing (2) so that the screw shaft (3) can rotate about the axis (O) and can move in the direction of the axis, and a linear motion body (5) which includes a nut (4) engaged with the screw shaft (3) and which is moved in the direction of the axis of the screw shaft (3) by the rotation of the screw shaft (3). Guide surfaces (15, 15A, 15B, 15C, 15D) extending in the direction of the axis of the screw shaft (3) are provided to the housing (2). Each two of the guide surfaces (15) are disposed as a pair. The two guide surfaces (15) of each pair are not parallel to each other and face back to back. The linear motion body (5) is provided with guided bodies (16) respectively in contact with the guide surfaces (15).

Description

Linear motion guide mechanism Related applications

This application claims the priority of Japanese Patent Application No. 2011-094670 filed on April 21, 2011, and is incorporated herein by reference in its entirety.

The present invention relates to a linear motion guide mechanism used for guiding a linear advance / retreat member that advances and retreats on a straight line in a machine tool, a measuring device, a conveyance device, and the like.

For example, as shown in FIGS. 17A and 17B, as a part used for linear motion guidance in a positioning unit such as a machine tool, a linear rail 30 and a slide unit 31 that slides along the linear rail 30 are provided. There is a linear rail guide (also called linear motion rolling bearing). A variety of products having different sizes, shapes, and the like are sold by manufacturers, and it is possible to select an appropriate linear rail guide that suits application conditions such as load load and use posture.

Currently, there are two types of linear rail guides that are widely used. One is a circulation type in which rolling elements (not shown) such as balls and rollers in the linear rail guide circulate inside the slide unit 31. The other type is a finite stroke type in which rolling elements called cross roller guides are constrained by a cage. Both types use a hardened steel material such as bearing steel for the linear rail 30 or the rolling element that serves as a guide surface, thereby improving durability. As shown in FIGS. 17 (A) and 17 (B), by combining the ball screw mechanism and the linear rail guide and installing them in parallel with each other, the radial load and the moment load do not directly act on the ball screw mechanism. Thus, it is possible to realize a linear guide with excellent durability performance and high accuracy.

As a method of linear motion guidance without using a linear guide rail, in Patent Documents 1 to 4, vertical grooves and vertical guide surfaces are provided on the inner surface of the housing, and a bearing such as a cam follower is rotated along these vertical grooves and vertical guide surfaces. Technologies have been proposed to achieve linear motion guidance by running. Patent Document 5 proposes a technique for realizing linear motion guidance by providing a plurality of bearings arranged in the circumferential direction on the housing side and applying the outer ring surface of these bearings to a linearly advancing / retracting member disposed at the center. Has been.

JP 2007-216280 A JP-A-2-186157 JP 2010-179323 A JP 2007-333046 A JP 2001-212229 A

As shown in FIG. 18, the cylinder type linear actuator 7 driven by the motor 6 is being used in production facilities and transfer facilities as an alternative to an air cylinder for the purpose of energy saving. In the cylinder type linear motion actuator, the linear motion guide mechanism to be used is important, and the linear motion guide mechanism is a main factor that determines the appearance, cost, and performance of the cylinder type linear motion actuator.

The linear motion guide mechanism using a linear rail guide has a high rigidity and straightness guide structure, but the linear rail 30 is fixed by a plurality of fixing means 32 such as bolts as shown in FIGS. 17 (A) and 17 (B). This is an obstacle to promoting space saving and cost reduction.

Also, the linear motion guide mechanism that does not use a linear rail guide has the following problems. In Patent Documents 1 to 4, the main purpose is to prevent rotation of a linear motion member in a mechanism that converts rotational motion into linear motion (Patent Documents 1 and 2), and to be able to receive a load. Although there is a main purpose (Patent Documents 3 and 4), the latter also has a limit in the load direction that can be received due to the number and arrangement of bearings. In particular, the structure cannot be applied to a load from an oblique direction.

In the case of Patent Document 5, it is possible to receive loads from various directions, but the method of fixing the bearing and the adjustment of the pressing pressure to the linear advance / retreat member of the bearing are complicated.

An object of the present invention is to provide a linear motion guide mechanism and a linear motion actuator that can receive loads from various directions, have high rigidity, have high linear motion guide accuracy, and can be configured compactly.

The linear motion guide mechanism according to the present invention includes a housing, a screw shaft supported by the housing so as to be rotatable about the axis and immovable in the axial direction, and a nut screwed into the screw shaft. And a linear motion body that is moved in the axial direction of the screw shaft. In this linear motion guide mechanism, the housing is provided with a plurality of guide surfaces along the axial direction of the screw shaft, and each of the plurality of guide surfaces forms a pair, and the two guide surfaces forming the pair are not mutually connected. A plurality of guided bodies that are parallel to each other and face each of the guide surfaces are provided on the linear motion body.

According to this configuration, by rotating the screw shaft, the linear motion body including the nut moves in the axial direction of the screw shaft. At this time, the plurality of guided bodies provided on the linear moving body are moved in contact with the plurality of guide surfaces provided on the housing, respectively, so that the linear moving body is accurately guided in the axial direction of the screw shaft. .

Each of the plurality of guide surfaces forms a pair, and the two guide surfaces that form a pair are not parallel to each other and face each other, so that the load acting on the linear motion body is distributed by each guide surface. I can receive it. Therefore, it can receive loads from various directions and large loads. In addition, the two guided bodies that are in contact with the two guide surfaces facing each other are in a state of sandwiching the portion of the housing that is sandwiched between the two guide surfaces, thereby improving the rigidity. Since the guide surface is provided on the inner surface of the housing and it is not necessary to provide a separate rail for guiding the guided body, a compact configuration can be achieved.

In the present invention, the guided body is a guide bearing including a support shaft provided to project from the outer surface of the linear motion body, and a rolling bearing attached to the support shaft and having an outer peripheral surface rolling to the guide surface. It is good. When the guided body is a guide bearing composed of a support shaft and a rolling bearing, the frictional resistance between the guide surface and the guided body is small, and the linear motion body can be moved smoothly.

A plurality of pairs of the guide surfaces may be provided so as to be positioned on both sides in the diameter direction of the screw shaft. With this configuration, the load acting on the linear motion body can be supported by each pair of guide surfaces with a good balance.

When the housing has a flat bottom surface, the guide surfaces may be inclined with respect to the bottom surface. The inclination angle of the guide surface may be determined according to the load condition.

The shaft center of the support shaft may be offset with respect to a straight line orthogonal to the axis center of the screw shaft and parallel to the shaft center of the support shaft. By adopting the above configuration, it becomes possible to receive a wider variety of loads, and it is possible to achieve load distribution and improvement of housing strength.

A plurality of the guided bodies may be provided side by side in the axial direction of the screw shaft on the linear motion body. In this case, the load capacity can be increased.

Further, the plurality of guided bodies may be arranged so as to be shifted from each other in the axial direction of the screw shaft on the linear motion body. In this case, it is possible to arrange the guided bodies that meet the load conditions.

When the guided body is composed of the nut and a moving bracket fitted to the outer periphery of the nut, the guided body on the side surface of the moving bracket is determined so that the axial center of the screw shaft does not coincide with the center of the moving bracket. You may arrange | position the said screw shaft in the location which is not provided. Even if the axis of the screw shaft does not coincide with the center of the moving bracket, the guided body is moved by rotating the screw shaft. Therefore, it is possible to arrange | position a screw shaft in the location where the to-be-guided body is not provided in the side surface of a moving bracket, and the freedom degree of arrangement | positioning of each component in a housing increases by it.

The guide bearing of the guided body may be a deep groove ball bearing. Deep groove ball bearings are easy to assemble, are easily available, and are low cost.

Further, the bearing of the guided body is an angular ball bearing, and a plurality of the angular ball bearings are arranged in the axial direction on the support shaft in a rear combination or a front combination, and preload is applied to the plurality of angular ball bearings. May be given. When the rolling bearing is a double row angular contact ball bearing, in addition to a load in a direction perpendicular to the guide surface, a load in the width direction of the guide surface can be received. Further, by applying the preload, it is possible to increase the rigidity by eliminating the gap between the bearings.

The guide bearing of the guided body may be a cam follower in which a roller that also serves as an outer ring is provided on the outer periphery of the support shaft via a rolling element. The cam follower can increase the width of the outer ring as compared with a ball bearing of a deep groove ball bearing or an angular ball bearing, and therefore can improve the load capacity of a single unit. When the rolling element is made of a roller such as a cylindrical roller, the load capacity can be further improved. Further, since the cam follower does not have an inner ring, the cam follower can be arranged in a narrow space in the diameter direction.

A resin coating may be applied to the outer peripheral surface of the outer ring of the guide bearing of the guided body. Thereby, the slidability between the outer ring of the guide bearing and the guide surface of the housing can be improved.

The guide surface may be a curved surface that is convex in an arc shape in a cross section perpendicular to the axial center of the screw shaft. In this case, the outer peripheral surface of the outer ring of the guide bearing can be prevented from making edge contact with the guide surface.

An oil sump groove extending in the axial direction may be provided within a width of the guide surface in contact with the guide bearing. In this case, the outer peripheral surface of the outer ring of the guide bearing is prevented from running out of lubricating oil, and the durability of the guide bearing can be improved.

A wear-resistant plate-like member having a surface hardness higher than that of the guide surface may be interposed between the guide surface and the rolling bearing of the guided body. For example, the plate-like member is provided by being attached to the surface of the guide surface. In this case, it is possible to improve the durability against the surface wear of the guide surface due to the rolling contact of the rolling bearing.

The surface of the guide surface may be subjected to surface hardening treatment. In this case, the durability of the guide surface can be improved.

The housing may be hardened by heat treatment. Also in this case, the durability of the guide surface can be improved.

The housing may include a housing main body and a guide surface forming member that has the guide surface and is fixed to the housing main body. In this case, the guide surface can be easily processed.

The guided body may be a sliding contact member that protrudes from the linear motion body and slides in contact with the guide surface. Even if the guided body is a sliding contact member that makes sliding contact with the guide surface, the linear motion body can be accurately guided in the axial direction of the screw shaft.

The linear motion actuator of the present invention includes any of the linear motion guide mechanisms described above and a drive source that rotates the screw shaft of the linear motion guide mechanism. Since the linear motion guide mechanism has the actions and effects described above, the linear motion actuator to which this linear motion guide mechanism is applied can receive loads from various directions, has high rigidity, and linear motion guide accuracy. Is good.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
(A) is a cutaway side view of a linear motion actuator provided with the linear motion guide mechanism according to the first embodiment of the present invention, and (B) is a cross-sectional view taken along the line IB-IB. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG.1 (B). It is a longitudinal cross-sectional view which shows the example from which the guide surface of a linear guide mechanism differs. It is a longitudinal cross-sectional view which shows the further different example of the same guide surface. It is a longitudinal cross-sectional view which shows the further different example of the same guide surface. It is a longitudinal cross-sectional view which shows the further different example of the same guide surface. It is a longitudinal cross-sectional view which shows the different example of the to-be-guided body of a linear guide mechanism. It is a longitudinal section showing a further different example of the guided body. It is a longitudinal section showing a further different example of the guided body. It is the fracture | rupture side view which abbreviate | omitted some linear motion guide mechanisms concerning 2nd Embodiment of this invention. It is the fracture | rupture side view which abbreviate | omitted a part of linear motion guide mechanism concerning 3rd Embodiment of this invention. It is a fracture front view of the linear guide mechanism concerning a 4th embodiment of this invention. It is a fracture front view of the linear guide mechanism concerning a 5th embodiment of this invention. It is a fracture front view of the linear guide mechanism concerning a 6th embodiment of this invention. It is a fracture front view of the linear guide mechanism concerning a 7th embodiment of this invention. (A) is a cutaway side view of a conventional linear motion guide mechanism, and (B) is an XVIIB-XVIIB sectional view thereof. It is a fracture side view of the conventional linear motion actuator.

A first embodiment of the present invention will be described with reference to FIGS. 1 (A), (B) to FIG. 1 (A) and 1 (B), the linear guide mechanism 1 includes a housing 2, a screw shaft 3 supported by the housing 2 so as to be rotatable about an axis O and immovable in the axial direction, And a linear motion body 5 including a nut 4 screwed onto the screw shaft 3. The linear motion guide mechanism 1 constitutes a linear motion actuator 7 together with a motor 6 that is a drive source.

The housing 2 includes a cylindrical linear motion guide portion 2a, a screw shaft support portion 2b coupled to the left and right ends of the linear motion guide portion 2a, and a coupling housing coupled to the tip of the screw shaft support portion 2b. A portion 2c, a shaft support portion 2d coupled to the other left and right ends of the linear motion guide portion 2a, and a lid portion 2e coupled to the tip of the shaft support portion 2d.

The screw shaft 3 includes a ball screw portion 3a to which the nut 4 is screwed, a cylindrical surface portion 3b extending from the ball screw portion 3a to the base end side, and a male screw portion 3c. The screw shaft 3 has a cylindrical surface portion 3b rotatably supported by a double row support bearing 8 fitted to the inner periphery of the screw shaft support portion 2b of the housing 2. The support bearing 8 is a rolling bearing such as an angular ball bearing. A retaining nut 9 is screwed onto the male screw portion 3c, and the axial movement of the screw shaft 3 is restricted. The screw shaft 3 is coupled to a rotating shaft 6 a of the motor 6 installed outside the housing 2 through a coupling 10 housed in a coupling housing portion 2 c of the housing 2.

The nut 4 is, for example, a ball nut that circulates a ball (not shown) along a contact surface with the ball screw portion 3a of the screw shaft 3, and the ball screw portion 3a and the nut 4 constitute a ball screw mechanism 11. To do. The ball screw mechanism 11 rotates the screw shaft 3 so that the linear motion body 5 including the nut 4 moves in the axial direction.

The linear moving body 5 includes the nut 4, a moving bracket 12 fitted to the outer periphery of the nut 4, and a shaft 13 extending from the moving bracket 12 in the axial direction of the screw shaft 3. The nut 4 and the moving bracket 12 are coupled to each other so as not to rotate with each other by a spline or the like, and are not movable in the axial direction with respect to a retaining means (not shown). As shown in FIG. 2, the shaft 13 has a cylindrical shape, and a distal end portion protruding from the nut 4 of the screw shaft 3 is inserted into the hollow portion. The shaft 13 is supported so as to be slidable in the axial direction of the screw shaft 3 by a linear sliding bearing 14 fitted to the inner periphery of the shaft support portion 2 d of the housing 2. The moving bracket 12 and the shaft 13 may be integrated or separate. Further, the linear motion body 5 may have the shaft 13 attached to the nut 4 without having the moving bracket 12. Further, an output member (not shown) corresponding to the shaft 13 may be provided integrally with the nut 4 without having the shaft 4 separate from the nut 4.

As shown in FIG. 1B, the linear motion guide portion 2a of the housing 2 has a cylindrical shape having a substantially square cross section perpendicular to the axial direction of the screw shaft 3, and has a constant width along the axial direction of the screw shaft 3 on the inner surface thereof. A plurality of guide surfaces 15 (15A to 15D) are provided. Each guide surface 15 is for guiding a guided body 16 described later in the axial direction of the screw shaft 3. In the example shown in the figure, a total of four guide surfaces 15 are provided, one on each side. Each of the plurality of guide surfaces 15 is arranged in pairs, that is, a guide surface 15A and a guide surface 15B, and a guide surface 15C and a guide surface 15D, respectively, and each pair of guide surfaces 15 is not parallel to each other. They are facing each other. That is, each pair of guide surfaces 15 has a width surface that intersects with each other on its extension line. Each pair of guide surfaces 15 is inclined with respect to the flat bottom surface F of the housing 2 at angles of plus 45 ° and minus 45 ° (θ _A , θ _B , θ _C , θ _D = 45 °).

The moving bracket 12 of the linear moving body 5 is provided with guided bodies 16 that are in contact with the guide surfaces 15 respectively. The guided body 16 is a guide comprising a trunnion shaft-like support shaft 17 provided to protrude from the outer surface of the movable bracket 12 and a rolling bearing 18 attached to the support shaft 17 and having an outer peripheral surface rolling to the guide surface 15. It is considered as a bearing. The support shaft 17 of each guided body 16 has its axis P intersecting the axis center O of the screw shaft 3. The rolling bearing 18 of this embodiment is a deep groove ball bearing. The guided body 16 may be provided in a portion other than the moving bracket 12 of the linear moving body 5, that is, the nut 4 or the shaft 13.

In the linear motion actuator 7 to which the linear motion guide mechanism 1 is applied, the linear motion body 5 including the nut 4 is moved in the axial direction of the screw shaft 3 by rotating the screw shaft 3 by driving the motor 6. At this time, the plurality of guided bodies 16 provided on the moving bracket 12 of the linear moving body 5 are moved in contact with the plurality of guide surfaces 15 provided on the housing 2, so that the linear moving body 5 is screw shafts. 3 is guided with high accuracy in the axial direction.

Each of the plurality of guide surfaces 15 forms a pair, and the two guide surfaces 15 that form a pair are not parallel to each other and face each other, so that the load acting on the linear moving body 5 is applied to each guide surface 15 by a load. Received in a distributed manner. Therefore, it can receive loads from various directions and large loads. In addition, the two guided bodies 16 that are in contact with the two guide surfaces 15 that face each other are pressed against the respective guide surfaces 15 to sandwich the portion of the housing 2 that is sandwiched between the two guide surfaces 15. , Rigidity can be improved. Since a plurality of pairs of guide surfaces 15 are provided so as to be located on both sides of the screw shaft 3 in the diametrical direction, the load acting on the linear motion body 5 can be supported by each pair of guide surfaces 15 with a good balance. . Since the guide surface 15 is provided on the inner surface of the housing 2 and a rail for guiding the guided body 16 does not need to be provided separately, a compact configuration can be achieved.

In this embodiment, the guided body 16 is a guide bearing including a support shaft 17 and a rolling bearing 18, and the outer ring 18 a of the rolling bearing 18 is in rolling contact with the guiding surface 15, so that the guiding surface 15 and the guided body 16 are Therefore, the linear motion body 5 can be moved smoothly. Further, the deep groove ball bearing used as the rolling bearing 18 is easy to assemble, easily available, and low cost.

As shown in FIG. 4, the guide surface 15 may be a curved surface that is convex in an arc shape in a cross section perpendicular to the axial center O of the screw shaft 3. In this case, the outer peripheral surface of the outer ring 18 a of the rolling bearing 18 can be prevented from making edge contact with the guide surface 15.

Further, as shown in FIG. 5, an oil sump groove 20 extending in the axial direction may be provided within the width of the guide surface 15 in contact with the rolling bearing 18. In this case, the outer peripheral surface of the outer ring 18a of the rolling bearing 18 is prevented from running out of lubricating oil, and the durability of the rolling bearing 18 can be enhanced.

Further, as shown in FIG. 6, a plate member 21 for wear resistance having a surface hardness higher than that of the guide surface 15 may be interposed between the guide surface 15 and the rolling bearing 18. For example, the plate-like member 21 is provided by being attached to the surface of the guide surface 15. In this case, durability against surface wear of the guide surface 15 due to rolling contact of the rolling bearing 18 can be enhanced.

Instead of providing the plate-like member 21, the surface of the guide surface 15 may be subjected to surface hardening treatment. Also in this case, the durability of the guide surface 15 can be improved. Alternatively, the entire housing 2 may be cured by heat treatment. Also in this case, the durability of the guide surface 15 can be improved.

As shown in FIG. 7, the housing 2 may be composed of a housing body 2A and a guide surface forming member 22 having a guide surface 15 and fixed to the housing body 2A. The housing body 2A and the guide surface forming member 22 are fixed by an appropriate method such as bolt fixing. In this case, the guide surface 15 can be easily processed.

As shown in FIG. 8, the rolling bearing 18 may be an angular ball bearing in which a plurality of rolling bearings 18 are arranged in the axial direction on the support shaft 17 in a combination of the back surface or the front surface. It is desirable to apply a preload to the plurality of angular ball bearings. If the rolling bearing 18 is a double-row angular ball bearing, in addition to the load in the direction perpendicular to the guide surface 15, a load in the width direction of the guide surface 15 can be received. Further, by applying the preload, it is possible to increase the rigidity by eliminating the gap between the bearings.

As shown in FIG. 9, the guide bearing constituting the guided body 16 is provided with a roller 24c that also serves as an outer ring via a rolling element 24b on the outer periphery of the support shaft 24a, instead of the combination of the support shaft 17 and the rolling bearing 18. The cam follower 24 may be used. The cam follower 24 can increase the width of the roller 24c, which is an outer ring, as compared with the rolling bearing 18 such as a deep groove ball bearing or an angular ball bearing, and therefore can improve the load capacity of a single unit. When the rolling elements 24b are made of rollers such as cylindrical rollers, the load capacity can be further improved. Moreover, since the cam follower 24 does not have an inner ring | wheel, it can be arrange | positioned in the space narrow in the diameter direction.

When the guide bearing is in rolling contact with the guide surface 15 such as the rolling bearing 18 or the cam follower 24, the outer peripheral surfaces 18a and 24c of the guide bearing may be coated with a resin such as polyurethane. Thereby, the slidability between the outer rings 18a and 24c and the guide surface 15 can be improved.

Further, the guided body 16 may be in sliding contact with the guide surface 15 as shown in FIG. The guided body 16 is provided with a sliding contact member 26 that slides in contact with the guide surface 15 on a support member 25 that is provided on the movable bracket 12 so as to protrude to the outer peripheral side. Even if the guided body 16 is in sliding contact with the guide surface 15, the linear motion body 5 can be accurately guided in the axial direction of the screw shaft 3.

As in the second embodiment shown in FIG. 11, a plurality of guided bodies 16 may be provided on the linear motion body 5 in the axial direction of the screw shaft 3. Thereby, the load capacity can be increased. Further, as in the third embodiment shown in FIG. 12, a plurality of guided bodies 16 may be arranged on the linear motion body 5 so as to be shifted from each other in the circumferential direction of the screw shaft 3. The plurality of guided bodies 16 may be paired guided bodies 16 or guided bodies 16 belonging to different pairs. In this way, by shifting the positions in the axial direction of the plurality of guided bodies 16 to form a staggered arrangement, the guided bodies 16 can be arranged in accordance with the load conditions.

In the above embodiment, the angles θ _A , θ _B , θ _C , and θ _D with respect to the bottom surface F of the housing 2 of each guide surface 15 are set to plus 45 ° or minus 45 °. Also good. The inclination angle of the guide surface 15 may be determined according to the load condition. For example, in the fourth embodiment shown in FIG. 13, the left and right pairs of guide surfaces 15 are inclined with respect to the flat bottom surface F of the housing 2 at angles of plus 30 ° and minus 30 ° (θ _A , θ _B , θ _C , θ _D = 30 °). In the fifth embodiment shown in FIG. 14, the inclination angles of the guide surfaces 15 are different, θ _A is plus 45 °, θ _B is minus 15 °, and θ _C and θ _D are plus 30 °. It is set to minus 30 °.

Further, in the fourth embodiment shown in FIG. 13 and the fifth embodiment shown in FIG. 14, the shafts 17 of all the guided bodies 16 or the shaft centers P of some of the guided bodies 16 are screwed. It is offset with respect to a straight line orthogonal to the axis O of the shaft 3 and parallel to the axis P of the support shaft 17. As a result, it is possible to receive a wider variety of loads, and it is possible to distribute the load and improve the housing strength.

The shape of the cross section orthogonal to the axial direction of the screw shaft 3 of the linear motion guide portion 2a of the housing 2 is not limited to a polygon such as a square, but is a circle or an ellipse as shown in the sixth embodiment shown in FIG. It is good also as a shape (not shown). The number of pairs of guide surfaces 15 may be three or more as shown in the sixth embodiment shown in FIG. In short, the shape and arrangement of the housing 2 and the guide surface 15 may be determined in accordance with the location where the linear guide mechanism 1 is used, the posture, the load condition, and the like.

The shaft center O of the screw shaft 3 and the center of the moving bracket 12 do not have to coincide with each other. Even in that case, the linear motion body 5 can be moved by rotating the screw shaft 3. The seventh embodiment shown in FIG. 16 is an example of a linear motion guide mechanism 1 in which the axial center O of the screw shaft 3 and the center Q of the moving bracket 12 do not coincide with each other. The screw shaft 3 is disposed at a location where the guide body 16 is not provided. Thus, since the arrangement of the screw shaft 3 can be arbitrarily determined, the degree of freedom of arrangement of each component in the housing 2 is increased.

As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily assume various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications should be construed as being within the scope of the invention defined by the claims.

DESCRIPTION OF SYMBOLS 1 ... Linear motion guide mechanism 2 ... Housing 2A ... Housing main body 3 ... Screw shaft 4 ... Nut 5 ... Linear motion body 6 ... Motor (drive source)
7 ... Linear actuator 12 ... Moving brackets 15, 15A, 15B, 15C, 15D ... Guide surface 16 ... Guided body 17 ... Support shaft 18 ... Rolling bearing 18a ... Outer ring 20 ... Oil reservoir groove 21 ... Plate-like member 22 ... Guide Surface forming member 24 ... cam follower 24c ... roller (outer ring)
26 ... Sliding contact member F ... Bottom surface of housing O ... Axle shaft center P ... Axle shaft center Q ... Center of moving bracket

Claims (20)

The housing includes a housing, a screw shaft supported by the housing so as to be rotatable about the shaft center and immovable in the axial direction, and a nut screwed into the screw shaft, and is moved in the axial direction of the screw shaft by the rotation of the screw shaft. A linear motion guide mechanism having a linear motion body,
The housing is provided with a plurality of guide surfaces along the axial direction of the screw shaft, and each of the plurality of guide surfaces forms a pair, and the two guide surfaces that form the pair are not parallel to each other and face each other back.
Furthermore, the linear motion guide mechanism which provided the some to-be-guided body which contact | connects each said guide surface to the said linear motion body, respectively. 2. The guide bearing according to claim 1, wherein the guided body is a guide bearing including a support shaft provided to project from the outer surface of the linear motion body, and a rolling bearing attached to the support shaft and having an outer peripheral surface rolling to the guide surface. A linear motion guide mechanism. 3. The linear motion guide mechanism according to claim 2, wherein a plurality of pairs of the guide surfaces are provided so as to be positioned on both sides in the diameter direction of the screw shaft. 4. The linear motion guide mechanism according to claim 3, wherein the housing has a flat bottom surface, and the guide surfaces are inclined with respect to the bottom surface. 4. The linear motion guide mechanism according to claim 3, wherein the axis of the support shaft is offset with respect to a straight line perpendicular to the axis center of the screw shaft and parallel to the axis of the support shaft. 3. The linear motion guide mechanism according to claim 2, wherein a plurality of the guided bodies are provided side by side in the axial direction of the screw shaft on the linear motion body. The linear motion guide mechanism according to claim 2, wherein the plurality of guided bodies are arranged on the linear motion body while being shifted from each other in the axial direction of the screw shaft. The guide body according to claim 2, wherein the guided body includes the nut and a moving bracket fitted to an outer periphery of the nut, and the axial center of the screw shaft does not coincide with the center of the moving bracket, and the side surface of the moving bracket is A linear motion guide mechanism in which the screw shaft is arranged at a location where a guided body is not provided. The linear motion guide mechanism according to claim 2, wherein the guide bearing of the guided body is a deep groove ball bearing. In Claim 2, the said bearing of the said to-be-guided body is an angular contact ball bearing, this angular contact ball bearing is arranged in the axial direction on the said spindle, and two or more are provided by the back combination or the front combination, These several angular contact ball bearings Linear motion guide mechanism with preload applied to 3. The linear motion guide mechanism according to claim 2, wherein the guide bearing of the guided body is a cam follower in which a roller that also serves as an outer ring is provided on the outer periphery of the support shaft via a rolling element. 3. The linear motion guide mechanism according to claim 2, wherein the outer peripheral surface of the outer ring in the guide bearing of the guided body is resin-coated. 3. The linear motion guide mechanism according to claim 2, wherein the guide surface is a curved surface that is convex in an arc shape in a cross section perpendicular to the axial center of the screw shaft. 3. The linear motion guide mechanism according to claim 2, wherein an oil sump groove extending in the axial direction is provided within a width of the guide surface in contact with the guide bearing. 3. The linear motion guide mechanism according to claim 2, wherein a wear-resistant plate member having a surface hardness higher than that of the guide surface is interposed between the guide surface and the rolling bearing of the guided body. 3. The linear motion guide mechanism according to claim 2, wherein the surface of the guide surface is subjected to a surface hardening process. 3. The linear motion guide mechanism according to claim 2, wherein the housing is hardened by heat treatment. 2. The linear motion guide mechanism according to claim 1, wherein the housing includes a housing main body and a guide surface forming member having the guide surface and fixed to the housing main body. The linear motion guide mechanism according to claim 1, wherein the guided body is a sliding contact member that protrudes from the linear motion body and slides in contact with the guide surface. A linear motion actuator comprising the linear motion guide mechanism according to claim 1 and a drive source for rotating the screw shaft of the linear motion guide mechanism.

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