Actuator

To provide an actuator with which side face covers can be easily attached and detached without damaging a top face cover, and workability is enhanced, and cost can be reduced without upsizing the actuator, by fastening and fixing the actuator to a base stand from above the actuator in a state in which the side face covers are removed.In an actuator having a long screw shaft with a first roller rolling groove in a spiral shape formed on an outer periphery, an inner block where a screw hole through which the screw shaft penetrates is formed, and which has a second roller rolling groove that is formed on an outer periphery to be parallel with the screw shaft, an outer rail that faces the second roller rolling groove, and a plurality of rollers that are respectively arranged between the screw shaft and the inner block, and between the inner block and the outer rail, side face covers that are laid between a pair of end portion members that are installed at both end portions of the screw shaft, and a top face cover that is disposed to close an opening portion that is formed between the side face covers and is opened parallel with the screw shaft are included, the side face covers each includes a top plate that is formed to be parallel with the top face cover, and a side plate that hangs from one end of the top plate, and the end portion members each has posture retaining device that contacts a corner portion of the top plate and the side plate.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a National Stage of International Application No. PCT/JP2014/063820 filed May 26, 2014, claiming priority based on Japanese Patent Application No. 2013-120844 filed Jun. 7, 2013, the contents of all of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to an actuator, and particularly relates to a full cover type actuator including a dustproof mechanism.

BACKGROUND ART

Conventionally, there has been known a full cover type actuator including a dustproof mechanism, with the entire surface of the actuator structure section covered with a cover or the like. Further, as the form of an actuator like this, various forms are known, such as a rod type having a rod that is assembled to be extendable and contractible from the end portion of the actuator, and a slider type having a slider that moves along a longitudinal direction, on the top face of the actuator.

A full cover type actuator like this can be fixed to a base stand such as a worktable by various fixing methods, but has the problem that workability is unfavorable when a worker crawls under a base stand and attaches the actuator from below. In order to solve the problem like this, the actuator described in Patent Literature 1 has such a configuration that by removing the cover, the actuator is attached to a base stand with bolts from above the actuator.

CITATION LIST

Patent Literature

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, in the rod type actuator as described in Patent Literature 1, the cover can be easily removed, but a slider type actuator has the configuration in which an opening portion is formed on the actuator top face so that a slider can move, and the opening portion is closed with a top face cover. The top face cover is composed of a stainless steel tape in a thin film form, and therefore, is easily damaged when a stress along the width direction of the top surface cover is applied to the end portion of the top face cover. Consequently, a slider type actuator has the problem that unless positioning of the side face cover is performed accurately, when the side face cover is attached to the side face of the actuator, the side face cover contacts the top face cover which is stretched across the top face of the actuator, and the stress along the width direction is applied to the end portion of the top face cover, and thereby damages the top face cover. Further, since the side face cover cannot be easily attached and detached for the reason like this, the actuator cannot be fastened and fixed to the base stand from above the actuator with bolts or the like, at the time of installing the actuator on a base stand or the like, and there is no other choice but to adopt such a configuration that the actuator is fixed from below the base stand as hitherto, or such a configuration that flanges are formed on the side faces of the actuator, and the actuator is fastened and fixed to the base stand with bolts from above the actuator via the flanges, whereby a slider type actuator has the problem that attaching workability is still unfavorable, and in the case of forming the flanges, the actuator itself is upsized to make cost reduction difficult.

The present invention is made to solve the above described problem, and has an object to provide an actuator with which side face covers can be easily attached and detached without damaging a top face cover, workability is enhanced, and cost can be reduced without upsizing the actuator, by fastening and fixing the actuator to a base stand from above the actuator in a state in which the side covers are removed.

Means for Solving the Problems

An actuator according to the present invention is an actuator having a long screw shaft with a first roller rolling groove in a spiral shape formed on an outer periphery, an inner block where a screw hole through which the screw shaft penetrates is formed, and which has a second roller rolling groove that is formed on an outer periphery to be parallel with the screw shaft, an outer rail that faces the second roller rolling groove, and a plurality of rollers that are respectively arranged between the screw shaft and the inner block, and between the inner block and the outer rail, including a pair of side face covers that are laid between a pair of end portion members that are installed at both end portions of the screw shaft, and a top face cover that is disposed to close an opening portion that is formed between the side face covers, and is opened parallel with the screw shaft, wherein the side face covers each includes a top plate that is formed to be parallel with the top face cover, and a side plate that hangs from one end of the top plate, and the end portion members each has a posture retaining device that contacts a corner portion of the top plate and a side plate of the side face cover.

Effects of the Invention

According to the present invention, the top face cover can be prevented from being damaged at the time of attaching and detaching the side face covers to and from the end portion members, workability can be enhanced and cost can be reduced without upsizing the actuator.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of an actuator according to the present invention will be described with reference to the drawings. Note that the following embodiments do not restrict the invention according to each of claims, and all of combinations of features described in the embodiments are not always essential to the solution of the invention.

First Embodiment

FIG. 1is a perspective view of the actuator according to a first embodiment of the present invention,FIG. 2is an exploded view of the actuator according to the first embodiment of the present invention,FIG. 3is a partially exploded perspective view for explaining a configuration of an end portion member of the actuator according to the first embodiment of the present invention,FIG. 4is an arrow view in a direction L inFIG. 3,FIG. 5is a sectional view in a longitudinal direction of the actuator according to the first embodiment of the present invention, andFIG. 6is an assembly explanatory view showing a method for attaching a side face cover of the actuator according to the first embodiment of the present invention, in which (1) shows a state in which the side face cover is inserted, (2) shows a state in which the side face cover is rotated around a rotation axis parallel with a screw shaft, and (3) shows a state in which the side face cover is fastened and fixed.

As shown inFIG. 1, an actuator1according to the present embodiment is formed into a lean and long box shape having a pair of side face covers40that extend along a longitudinal direction, and are laid between a first end portion member31and a second end portion member that will be described later, a pair of end portion members formed of the first end portion member31and the second end portion member32which are installed at both ends of the side face covers40, and a top face cover50that closes an opening portion51that is formed along a longitudinal direction between facing surfaces of the side face covers40. The second end portion member32is covered with a side lid33, and forms an external shape of the actuator1according to the present embodiment, and in the first end portion member31and the second end portion member32, posture retaining devices70that will be described later are formed. Further, an inner block20that reciprocates along the opening portion51is attached via a detour device60for causing the top face cover50which is located in a position that is superimposed on the inner block20to make a detour.

As shown inFIG. 2, inside the actuator1according to the present embodiment, a screw shaft10where a first roller rolling groove11in a spiral shape is formed on an outer surface, and which extends along the longitudinal direction is supported in a rotatable state between the first end portion member31and the second end portion member32, and one end thereof is connected to a drive motor not illustrated that is disposed inside a drive device housing portion34that is formed in the first end portion member31. Further, the screw shaft10is inserted through a ball screw nut22that is formed at a lower end of the inner block20, and is engaged, with a ball screw roller not illustrated interposed between the screw shaft10and the inner block20. Further, in the inner block20, two second load roller rolling grooves25that are formed parallel with the screw shaft10are formed on each of both side surfaces, four in total. Further, a roller return passage26that is bored parallel with the screw shaft10is formed to correspond to the second load roller rolling groove25. Furthermore, a pair of lid bodies24are attached to both end surfaces of the inner block20.

The inner block20has reciprocating movement thereof guided by an outer rail80that is disposed at a lower end, and the outer rail80has a bottom portion83that extends along the longitudinal direction, and a pair of side wall portions82that are vertically provided from both ends of the bottom portion83and face both side faces of the ball screw nut22. Further, a moving plate21is attached to the inner block20in such a manner as to sandwich the top face cover50from above and below. Further, in the side wall portion82, a second roller rolling groove82ais formed to face the second load roller rolling grooves25, and the second load roller rolling grooves25and the second roller rolling groove82aform a roller rolling path. Further, in a lid body24, a through-hole24athrough which the screw shaft10is inserted, and direction changing paths24bthat cause the roller rolling path and the roller return passage26to communicate with each other are formed.

The inner block20is assembled to the outer rail80via a plurality of rollers not illustrated, and the rollers endlessly circulate by rolling in an endless track that is constituted of the roller rolling path, the direction changing paths24band the roller return passage26to guide the inner block20to be capable of reciprocating along the outer rail80.

The side face cover40has a top plate41that extends parallel with the top face cover50, and a side plate42that hangs from the top plate41. Further, at an end portion of the top plate41, a sealing portion43that contacts the top face cover50is formed. The sealing portion43may contact the top face cover in any manner as long as the sealing portion43can seal the top face cover50, but the sealing portion43is preferably magnetically attached to the top face cover50by a permanent magnet or the like being attached to the sealing portion43, for example. To the top face cover50, a stainless steel tape or the like having magnetism is preferably applied. Furthermore, the side face cover40is attached and fixed by the side plate42being fastened to the outer rail80with fastening bolts81.

Next, with reference toFIG. 5, the detour device60which is formed in the inner block20will be described. The detour device60includes a first guide portion61that is attached to the inner block20, and a second guide portion62that is urged by an urging device63that is attached to a lower end of the moving plate21. Since the top face cover50is lifted by the first guide portion61, the top face cover50and the inner block20do not contact each other, and the top face cover50is laid between the moving plate21and the inner block20by passing through a lower side of the second guide portion62and an upper side of the first guide portion61from outside of the moving plate21. Since the detour device is thus configured, the top face cover50and the inner block20are configured not to interfere with each other by reciprocating movement of the inner block20. The top face cover50is formed to have a wider width than the opening portion51, and closes the opening portion51by being disposed along the opening portion51under the side face covers40.

By being configured as above, in the actuator1according to the present embodiment, the inner block20is attached to be capable of reciprocating in an axial direction of the screw shaft, with rotational movement of the screw shaft10, by rotation of the drive motor.

Further, since the opening portion51which is formed along a trajectory of movement of the inner block20can always keep a closed state by the top face cover50, by the detour device60, dust that is generated from sliding portions of the screw shaft10and the ball screw nut22, sliding portions of the ball screw nut22and the outer rail80and the like does not leak outside through the opening portion51.

As shown inFIG. 3andFIG. 4, in the first end portion member31, the posture retaining devices70which prevent the top face cover50and the side face covers40from contacting one another at a time of attaching and detaching the side face covers40are formed. In the second end portion member32, the posture retaining devices70in the same shapes are also formed to face the posture retaining devices70which are formed in the first end portion member31.

The posture retaining device70includes a base point portion71that contacts a base end side of the top plate41of the side face cover40, and an inclined surface72that extends by inclining a predetermined angle from the base point portion71. The posture retaining device70prevents damage to the top face cover50at the time of attaching and detaching the side face cover40by allowing the side plate42to rotate around the rotation axis parallel with the screw shaft10with the base end side of the top plate41of the side face cover40as a base point.

That is, as shown inFIG. 4, in the side face cover40which is attached to the outer rail80, the side plate42is allowed to rotate around the rotation axis parallel with the screw shaft10to a direction to be away from the outer rail80with the base end side of the top plate41as the base point, and the top plate41is rotated to a position parallel with the inclined surface72, whereby the top plate41and the inclined surface72abut on each other to restrict rotation of the side face cover40. By being configured like this, the side face cover40rotates around the rotation axis parallel with the screw shaft10, and thereby moves the sealing portion43in a direction to be away from the top face cover50, whereby a horizontal component stress can be reduced in the end portion of the top face cover50, and damage to the top face cover50is prevented. As above, the inclined surface72inclines the predetermined angle from a width direction of the top face cover50, and is provided to extend parallel with the top plate41when the top plate41rotates around the rotation axis parallel with the screw shaft10.

Next, with reference toFIG. 6, a method for attaching the side face cover of the actuator1according to the present embodiment will be described. Detachment of the side face cover40can be performed in a reverse procedure from the attaching method.

As shown inFIG. 6(1), the actuator1according to the present embodiment is fastened and fixed to the base stand by the fixing bolt84from above the outer rail80in the state in which the side face covers40are removed. Thereafter, the side face cover40is inserted in such a manner that the top plate41of the side face cover40is caused to slide along the inclined surface72. In the position where the side face cover40is superimposed with the inner block20, the side face cover40is inserted in a groove23which is formed in the inner block20, and is assembled to be butted to a groove bottom.

As shown inFIG. 6(2), after the side face cover40is inserted until the base end side of the top plate41and the base point portion71abut on each other, the side plate42is rotated around the rotation axis parallel with the screw shaft with the base end side of the top plate41as the base point. Since with the rotation, the sealing portion43moves in a direction to approach the top face cover50, the sealing portion43does not apply an unnecessary horizontal component stress to the top face cover50, and therefore, the sealing portion43contacts the top face cover50without damaging the end portion of the top face cover50and can close the opening portion51. The side face cover40rotates while sliding on the groove bottom in the range of the groove width of the groove23of the inner block20, and therefore positioning of the side face cover40can be performed easily.

As shown inFIG. 6(3), the side plate42is fastened and fixed to the outer rail80with the fastening bolt81in the state in which the sealing portion43closes the top face cover50.

In this manner, in the actuator1according to the present embodiment, the side face cover40can be easily attached and detached without damaging the top face cover50by rotating the side face cover40around the rotation axis parallel with the screw shaft10via the posture retaining device70, and the actuator1is fastened and fixed to the base stand with the fixing bolt84from above the actuator1according to the present embodiment in the state in which the side face cover40is removed, whereby workability is enhanced, and cost can be reduced without upsizing the actuator1.

Further, the posture retaining device70can allow the side plate42to rotate around the rotation axis parallel with the screw shaft10with the base end portion of the top plate41of the side face cover40as the base point, and therefore, the rotational operation of the aforementioned side face cover40can be reliably realized with the simple configuration.

Further, when the side face cover40is rotated around the rotation axis parallel with the screw shaft10, the top plate41and the inclined surface72abut on each other to restrict rotation of the side plate42, and therefore, the side face cover can be prevented from erroneously contacting the top face cover50with the rotational operation.

Further, the inclined surface72functions as a restriction section that restricts rotation of the side face cover40by abutting on the top plate41, and therefore, can contribute to enhancement in attaching workability and cost reduction due to the fact that the base point portion71and the inclined surface72can be integrally configured.

Second Embodiment

In the actuator1according to the first embodiment that is described above, explanation is made about the case where the posture retaining device70is integrally formed by the base point portion71and the inclined surface72. In an actuator of a second embodiment that will be described next, explanation will be made about an example of posture retaining device having a form different from the first embodiment. Note that the same or similar members as or to those in the case of the aforementioned first embodiment will be assigned with the same reference numerals and explanation thereof will be omitted.

FIG. 7is a partially exploded perspective view for explaining a configuration of an end portion member of the actuator according to the second embodiment of the present invention, andFIG. 8is an arrow view in a direction L inFIG. 7.

As shown inFIG. 7, in a first end portion member31′ of the actuator2according to the present embodiment, a support guide pin71′ as a base point portion is provided to protrude on a surface facing a second end portion member not illustrated. Further, a stopper73that is separated from the pin71′ and protrudes from the first end portion member31′ is attached.

As shown inFIG. 8, the stopper73is attached at a position that restricts rotation of the top plate41when the side face cover40is rotated around the rotation axis parallel with the screw shaft10similarly to the actuator1according to the aforementioned first embodiment, and thereby an operational effect similarly to the posture retaining device70of the actuator1according to the first embodiment can be provided.

According to the actuator2according to the present embodiment, since the posture retaining device is configured by the pin71′ and the stopper73, a range of a rotational operation can be finely adjusted by properly changing the size of the stopper73, and workability of attaching and detaching work of the side face cover40can be enhanced more.

The present invention is not limited to the above described embodiments, and various modifications can be made within the range without changing the gist of the present invention. For example, in the actuators1and2according to the first and second embodiments, explanation is made on the example in which the screw shaft10is assembled to the ball screw nut via balls, with respect to the shaft member and the moving member, but the screw shaft10can be also screwed into the ball screw nut without using balls.

Further, in the actuators1and2according to the first and second embodiments, explanation is made on the case where the screw shaft10is adopted, with respect to the shaft member and the moving member, but various linear guide devices such as a spline device and a linear guide can be also adopted without being limited to the screw shaft.

Further, in the actuators1and2according to the first and second embodiments, explanation is made on the case where a magnet is used for the sealing portion43, but closure of the top face cover50and the side face cover40may be performed by only contact without using a magnet, as long as the closure of the top face cover50and the side face cover40can be reliably performed. It is obvious from the statements of the claims that a mode in which such a modification or an improvement is added can be also contained in the technical range of the present invention.

REFERENCE NUMERALS