JPH077837U - Dust-proof structure of linear actuator - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a direct-acting actuator with a dustproof device that is highly rigid, compact, and lightweight. A linear motion actuator includes a linear motion guide device 10 provided inside a housing 1, a carriage 20 guided by the linear motion guide device 10 and a drive device for axially driving the carriage 20 via a ball screw. Carriage 20 on one side
Has a slit S that is long in the moving direction. Pulleys 50 are arranged at both ends of the housing 1, and the carriage 2
0, a loop of a seal band 60 is attached to allow the carriage 20 to linearly move and circulate through the pulley 50.
Cover. Since it is not necessary to pass the seal band 60 inside the carriage 20, it is possible to reduce the size and weight with a simple structure and high rigidity.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement in a dustproof structure structure of a linear motion actuator having a carriage incorporated in a housing and linearly driven in the axial direction.

[0002]

[Prior art]

 Examples of this type of actuator include those shown in FIGS. 6 and 7. In this system, a pair of parallel linear guide devices (linear guide devices) 102 are arranged on an elongated base 101, a carriage 105 is fixedly attached to a slider 104 which linearly moves on a guide rail 103, and a carriage for the carriage 105. 105 is connected to a ball nut 107 of a ball screw device 106 which is a rotation-linear conversion drive mechanism. Then, by rotating the ball screw shaft 109 by the AC servo motor 108, the carriage 105 is linearly moved in the axial direction along the guide rail 103. The work W, which is a driven body, is fixed to the work mounting seat surfaces 110 on both sides of the carriage 105 by screws, and the linear movement and the precision positioning operation are repeated with high accuracy.

In the above actuator, most of the outer circumference is covered with a side cover 111, an upper cover 112, an end face cover 113, and the like to ensure safety and aesthetics, and to secure precision parts such as a linear guide device 102 and a ball screw device 106. We are trying to prevent dust. However, since the workpiece mounting seat surface 110 of the carriage 105 must be exposed to the outside, an axial gap (slit) S between the side cover 111 and the upper cover 112 over the entire length of the moving range L of the carriage 105. Is open. Therefore, dust and the like enter and exit through the opening of the slit S, which is not perfect in terms of dust prevention.

On the other hand, conventionally, for example, a linear motion actuator in which a slit opening in a moving range of a carriage is covered with a movable belt has been proposed as disclosed in Japanese Utility Model Application Laid-Open No. 4-60642 by the present applicant. There is. As shown in FIGS. 8 and 9, a carriage 121 is mounted on a cylinder tube 120 having a long axial slit S on one side surface (upper surface) slidably in the axial direction. Is connected to a ball nut 124 screwed to a screw shaft 123 of a ball screwing device 122, and is linearly driven in the axial direction by an AC servomotor 125.

A table body 126 is projectingly provided on the upper portion of the carriage 121, penetrates the slit S and is exposed to the outside of the cylinder tube 120, and the upper surface of the table body has mounting bolt holes 127 at four corners. It is a surface 128. As shown in FIG. 9, an insertion hole 130 for the screw shaft 123 is formed in the carriage 121 in the axial direction, and a nut accommodating space 131 for accommodating the feed ball nut 124 is formed in the center of the insertion hole 130. Has been done. The nut storage space 131 is provided with a square groove 131a at the center of its ceiling, and is open downwardly. In the nut storage space 131, a ball nut 124 having a square anti-rotation projection 132 is incorporated by fitting the projection 132 into the square groove 131a.

The left and right sides of the carriage 121 are each projected in a V shape, and they are fitted to the inner surface of the rhombus inside the cylinder tube 120 via sliding members (not shown) attached to both outer edges thereof. The table body 126 projecting from the carriage 121 has a band insertion hole 136 through which the seal band 135 is inserted. The band insertion hole 136 has a band guide surface 137 formed in a gentle mountain shape that curves in an upward warp, and opens in the front and rear of the lower surface of the table body. A thin steel seal band 135 is inserted through the opening and inserted into the band insertion hole 136.

After the carriage 121 is assembled in the cylinder tube 120, the opening of the slit S on the upper surface of the cylinder tube 120 is covered with the above-mentioned seal band 135. A strip-shaped rubber magnet is attached along the opening side edge of the slit S, and its magnetic force attracts the seal band 135 to enhance the sealing performance. Both ends of the seal band 135 are fixed to the end cap 140 and the head cap 141, respectively, and the middle part of the seal band 135 is placed on the curved band guide surface 137 of the carriage 121.

Now, when the AC servomotor 125 is driven in forward / reverse rotation, the screw shaft 123 rotates accordingly, and the ball nut 124 moves in the front / rear direction. As a result, the carriage 121 is moved forward and backward while being guided by the cylinder tube 120, and the work attached to the work mounting seat surface 128 of the table 126 is arbitrarily moved in the axial direction of the linear motion table device to a predetermined position. Can be stopped exactly.

At this time, the seal band 135 prevents dust from entering the inside through the slit S of the cylinder tube 120. The table body 126 moves while pushing up the seal band 135 by the curved surface of the band guide surface 137 during its movement.

[0010]

[Problems to be solved by the device]

 However, in the above-mentioned conventional example in which the slit S of the cylinder tube 120 is closed by the seal band 135, while the high dustproof effect is obtained, the following problems occur. Since the seal band 135 is passed through the carriage 121, the carriage structure is complicated and the rigidity of the carriage 121 cannot be increased.

Since the band insertion hole 136 is provided so as to penetrate through the central portion of the table body 126 provided on the carriage 121, the position of the mounting bolt hole 127 of the work mounting seat surface 128 is advantageous in terms of rigidity in the central portion. However, the carriage 121 becomes large in size because it cannot be provided at the four corners and must be arranged at four corners. By the way, in the case of a large class linear motion actuator with a large load capacity, it is most important to have high rigidity in order to convey the work at high speed and to position it with high accuracy. The carriage of the linear motion actuator is a member that connects the linear motion guide part and the work, and is one of the important factors that determine the rigidity of the linear motion actuator, and there is no structure that cannot increase the rigidity. Appropriate.

[0012] Therefore, the present invention has been made by paying attention to the dust-proof structure of the above-mentioned conventional linear motion actuator. A seal band for sealing a slit for allowing the carriage to move in the axial direction is provided on the outside of the carriage. It is an object of the present invention to solve the above-mentioned conventional problems by providing a dustproof structure that is movable in the axial direction in cooperation with mounting, a seal band and a carriage.

[0013]

[Means for Solving the Problems]

 To achieve the above object, the present invention provides a housing which is long in the axial direction, a linear motion guide device provided in the housing, and a housing which is axially movable through the linear motion guide device. The carriage is provided with a drive device that drives the carriage in the axial direction via a ball screw. A slit that is long in the moving direction of the carriage is provided on one surface of the housing. In a linear actuator that has a workpiece mounting seat surface that penetrates and projects to the outside of the housing, place pulleys on both axial ends of the housing and fix one end of the seal band to one end of the carriage. Then, fold the other end of the seal band through the pulley and fold it back at one end of the housing. The movable loop seal band is formed by fixing the other end of the Yarijji, characterized dustproof structure so as to seal the opening of the slit in the mobile loop of the sealing band.

Here, the main body of the housing may be an extruded product to form hollow holes or grooves in the axial direction, and the lower part of the movable loop of the seal band may be passed through these holes or grooves. . In addition, a concave groove that engages with the side edge of the seal band can be formed in the side edge portion of the slit opened on one surface of the housing.

Further, a guide plate is attached to a lower part of the movable loop of the seal band which is passed through the hollow hole or groove of the main body of the housing, and the guide plate is engaged with the hollow hole or groove. Can be made. Further, a pair of protrusions having an L-shaped cross section and facing each other may be provided on the inner surface of the cover that covers the upper surface of the housing, and the sound absorbing material may be attached between these protrusions.

[0016]

[Action]

 The dust-proof structure of the linear actuator of this invention has pulleys at both ends of the housing in the axial direction, the seal band is fixed to one end of the carriage, and is folded back through the pulley to move the seal loop. And the other end of the band was fixed to the other end of the carriage. The loop of the seal band is integrated with the carriage that linearly moves back and forth in the axial direction, and circulates and reciprocates in the axial direction to seal the opening of the slit. Therefore, it is not necessary to pass the seal band inside the carriage, and therefore the carriage can be solid and have a simple structure and high rigidity, and can be easily miniaturized.

In addition, the hollow structure for achieving both high rigidity and light weight of the housing can be effectively used by passing the lower part of the movable loop of the seal band through the hollow hole or groove formed in the housing. . Further, if a concave groove that engages with the side edge of the seal band is formed in the side edge portion of the slit of the housing, the sealing action of the seal band is promoted and the dustproof and soundproof effect is increased.

If a guide plate is attached to the lower part of the movable loop of the seal band, stable running of the seal band can be ensured even with a large actuator having a long seal band. Also, if a pair of protrusions having an L-shaped cross section are provided on the inner surface of the cover that covers the upper surface of the housing and a sound absorbing material is attached between these protrusions, the rigidity of the cover can be increased and at the same time, the soundproof performance Can be improved.

[0019]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention, FIG. 1 is a transverse sectional view of a linear actuator, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a front view showing a cutaway view of a part of the linear guide device.

In the linear motion actuator of this embodiment, a linear motion guide device (linear guide device) 10 is provided in a housing 1 which is long in the axial direction, and moves linearly through the linear motion guide device 10. A carriage 20 freely attached is provided. Further, in order to accurately convey the carriage 20 in the axial direction at a selected speed to a selected position, a drive device 40 for driving the carriage 20 in the axial direction via a ball screw device 30 is provided.

The housing 1 is provided with a slit S that is long in the moving direction of the carriage 20 on the upper surface, and the carriage 20 has a work mounting seat surface 24 a that penetrates the slit S and projects to the outside of the housing 1. ing. The dustproof structure of the linear actuator having such a structure is as follows. Pulleys 50 are arranged at both ends of the housing 1 in the axial direction, one end of the seal band 60 is fixed to one end of the carriage 20, and the pulley 50 is folded back at one end of the housing 1 to reach the other end of the housing 1. It is folded back through another pulley 50 and fixed to the other end of the carriage 1 to form a movable loop of the seal band 60, and the opening of the slit S is closed by the movable loop of the seal band 60.

A more detailed description will be given below. The housing 1 includes a housing main body 2, a pair of left and right side covers 3 and 3, an upper cover 4, an end cover 5 that has a bearing built in and covers one end, and a motor bracket 6 that has a bearing built in and covers the other end. It consists of In the case of this embodiment, the housing body 2 is an extruded product made of aluminum and has a substantially chevron cross-section with an open upper part. The bottom of the housing main body 2 to which a load is applied is required to have rigidity so that it is not deformed under the influence of the load and the accuracy of conveyance of the linear motion actuator is deteriorated. In this embodiment, the bottom wall of the housing body 2 has a hollow structure having a large number of through holes 7 in the axial direction to ensure both rigidity and weight reduction.

A step portion 8 extending over the entire length is formed symmetrically on the left and right sides of the floor surface of the housing body 2, and a pair of left and right straight portions are formed on the floor surface of the left and right step portions 8. The guide rails 11 of the dynamic guide device 10 are fixed by bolts (not shown). A slider 12 is movably mounted on the guide rail 11 along the rail. In this embodiment, two sliders 12 are arranged for each guide rail 11.

Here, a schematic structure of the linear motion guide device 10 will be described. As shown in an enlarged view in FIG. 4, the guide rail 11 has a rectangular cross section and is formed on both left and right side surfaces thereof so as to extend in the axial direction. It has a rolling element rolling groove 13. The slider 12 has a U-shaped cross section including an upper plate portion 14 and sleeve portions 15 extending downward from both side portions thereof, and the left and right inner side surfaces of the sleeve portions 15 have rolling element rolling grooves of the guide rail 11. A rolling element rolling groove 16 is formed at a position opposed to 13. Further, a circulation path 17 is formed in the sleeve portion 15 so as to communicate with the rolling element rolling grooves 13 and 16, and the rolling path and the circulating path 17 formed by the rolling element rolling grooves 13 and 16 are formed. A large number of balls 18, which are rolling elements, are held by a cage 19 and are rotatably inserted. The guide rail 11 is provided with rail mounting bolt holes 11a at a plurality of positions at intervals in the length direction, and mounting slider bolt holes 12a are provided at four corners on the upper surface of the slider 12.

The carriage 20 has a top plate 21 having a width slightly smaller than the inner width of the housing 1 and a length of about two slides 12, and a ball formed so as to protrude downward from the lower surface thereof. And a nut mounting body portion 22. Then, both the left and right sides of the top plate 21 are placed on the upper surfaces of the sliders 12 of the left and right linear motion guide devices 10, and fixed by the mounting bolts 27 screwed into the bolt holes 12a, so that the four sliders 12 are mounted. It is supported and is installed in the housing 1 so as to be movable in the axial direction.

On the upper surface of the top plate 21, a concave groove 23 is formed in the central portion over the entire length, and convex portions 24 extending over substantially the entire length are formed on both left and right sides of the concave groove 23. The upper surfaces 24a of the protrusions 24 are work mounting seat surfaces that are slightly higher than the upper cover 4 and project outward. Further, stepped portions 24b lower than the work mounting seat surface 24a are formed at both ends of the convex portion 24 in the length direction.

The protrusions 24 are formed such that the left and right protrusions 24 are located right above the guide rails 11 of the left and right linear motion guide devices 10, respectively. This is to make the thickness of the carriage top plate 21 as thin as possible by arranging the work mounting surface 24a of the carriage 20 on the axis of the linear motion guide device 10 which is most advantageous in terms of rigidity. Is.

The ball screw device 30 includes a ball screw shaft 31 and a ball screw nut 32. The ball screw shaft 31 has a spiral groove on the outer peripheral surface, one end is supported by the end cover 5 via a bearing, and the other end is supported by the motor bracket 6 via a bearing. It is arranged in the center of the width of the housing 1 in parallel with the rail 11. One shaft end of the ball screw shaft 31 supported by the motor bracket 6 projects outward from the motor bracket 6 and is connected to the output shaft of the drive motor 40.

The ball screw nut 32 has a spiral groove facing the spiral groove of the ball screw shaft 31 on its inner peripheral surface, and the ball screw shaft 31 is rotated through a large number of balls rolling in both spiral grooves facing each other. It is screwed to. The ball screw nut 32 of this embodiment is, for example, an end cap circulation system, and ball circulation members (end caps) 35 are detachably joined to both end surfaces of the nut. In addition, a ball return passage formed of an axial through hole is provided in the thick portion of the nut body. The ball circulation member 35 is provided with a curved path on the end surface on the side where it is joined to the nut body, which connects the opposing spiral grooves and the ball return path.

When the ball screw shaft 31 and the ball screw nut 32 rotate relative to each other, a steel ball advances while rolling in both ball screw grooves of the ball screw shaft 31 and the ball screw nut 32 facing each other. Circulation returning to the original position is repeated through a curved path provided in the ball circulating member 35 at the end and a ball return path provided in the nut body.

However, the ball screw nut 32 is not limited to the end cap circulation type, and may be a tube circulation type or a top type. In the case of the tube circulation system, a U-shaped ball circulation tube is installed above the nut body as a ball circulation path for guiding and circulating the balls. The ball rolls in the opposite spiral grooves and is scooped up by the rear ball circulation tube, diagonally rides over the land portion of the ball screw shaft 31 along the tube and returns to the spiral groove again to infinitely circulate. It has a circular structure.

In the case of the top type, a top having a ball circulation groove is fitted in the thick part of the nut body, and the ball diagonally crosses over the land portion of the spiral groove of the ball screw shaft 31 along the top groove. It is a circulation system that returns between both spiral grooves facing each other. In this embodiment, as the drive unit 40, an AC servomotor is fixed to the outer surface of the motor bracket 6 with bolts. The output shaft of the AC servomotor 40 is connected to a ball screw shaft 31 rotatably supported in the housing 1 via a bearing via a coupling ring 39.

The ball screw nut 32, which is screwed to the ball screw shaft 31 via a ball, is fitted and fixed to the ball screw nut mounting body portion 22 of the carriage 20 so that the carriage 20 and the ball screw device 30 are connected to each other. Are connected. The carriage 20 needs to be moved in the axial direction in conjunction with the operation of the ball screw device 30 by the AC servomotor 40 and the ball screw nut 32. Therefore, a slit S is provided between the side cover 3 and the upper cover 4 as a passage for the convex portion 24 of the carriage 20 with a space therebetween. In this case, the slits S are provided in a pair of left and right corresponding to the pair of left and right convex portions 24 of the carriage 20.

The side cover 3 and the upper cover 4 forming the opening of the slit S are both extruded products made of aluminum, and the opposite end faces of a little thickness are Grooves 3a and 4a are formed respectively. In addition, a pair of left and right protrusions 4b having an L-shaped cross section are provided in the central portion of the lower surface of the upper cover 4 so as to face each other with a space therebetween. The facing distance is set to a size corresponding to the width of the ball screw nut 32 of the ball screw device 30. A sponge-like sound absorbing material 70 is fitted in a space surrounded by the protrusions 4b and 4b and the lower surface of the upper cover.

Although not shown, for example, a permanent magnet is fixed to the lower surface side of the carriage 20, while a proximity switch such as a Hall element facing the permanent magnet is attached to the inner surface of the housing body 2. The proximity switch and the permanent magnet detect the origin position of the carriage 20 in the direction of the linear movement axis, and by controlling the rotation of the AC servomotor 40, which is a drive unit, based on the origin detection signal, the position of the linear movement is detected. It is configured so that the decision can be made with high accuracy.

Although not shown, a contact position detector such as a limit switch for preventing overrun of the carriage 20 may be installed at the end of the housing 1. In that case, the wiring of the limit switch is Alternatively, it may be housed in a groove 2A provided on the outer side surface of the housing body 2 so as not to get in the way. In the linear actuator having the above structure, the housing 1 has a substantially sealed structure except for the opening of the slit S, and dust is prevented by closing the opening of the slit S with a movable seal band 60.

Since the left and right slits S have basically the same seal structure, only one side will be described and the other side will be omitted. Pulleys 50 for guiding the seal band 60 are arranged at four corners of the housing 1 as shown in FIG. That is, the pulley 50a at the upper corner of the motor bracket 6 is attached to the extended position of the slit S. The pulley 50b at the lower corner of the same motor bracket 6 is mounted directly under the pulley 50a. Further, the pulley 50c at the upper corner of the end cover 5 at the opposite end is attached to the extension position of the slit S. A pulley 50d at the lower corner of the same end cover 5 is attached directly under the pulley 50c.

The seal band 60 hung around the pulleys 50 at four positions is a flat band made of polyurethane-impregnated canvas, one end of which is fixed to the step portion 24 b provided on one end side of the carriage 20 with a set screw 61. Are locked. The other end of the seal band 60 is similarly fixed and locked to the step portion 24b provided on the other end side of the carriage 20 by a set screw 61. As a result, a loop of the seal band 60 that extends from one end of the carriage 20 to the other end of the carriage 20 via the pulley 50a, the pulley 50b, the pulley 50c, and the pulley 50d is formed.

At the opening of the slit S, both side edges of the seal band 60 are inserted into the groove 3a on the end surface of the side cover 3 and the groove 4a on the end surface of the upper cover 4 to enhance the sealing performance and effectively seal. I am trying to do it. The lower part of the loop of the seal band 60, that is, the part between the lower corner pulley 50b of the motor bracket 6 and the lower corner pulley 50d of the end cover 5 penetrates the housing body 2 in the axial direction. It passes through the inside of the through hole 7a directly below the guide rail 11 of the linear guide device 10 among the plurality of through holes 7 that are formed. A rectangular guide plate 63 is fixedly attached at a position just in the middle of the loop of the seal band 60, that is, at a position directly below the carriage 20 when the carriage 20 is located at the center of the housing 1 in the axial direction. . A slight gap is maintained between the side surface of the guide plate 63 and the inner wall of the through hole 7a to prevent the seal band 60 from lateral displacement.

The operation of locking the end portion of the seal band 60 to the step portion 24 b of the carriage 20 is performed after the carriage 20 is assembled to the slider 12 of the linear motion guide device 10, and the loop of the seal band 60 is formed. It After that, the side cover 3 and the upper cover 4 are attached. Next, the operation of the above embodiment will be described.

First, a work (not shown), which is a to-be-conveyed object, is attached to the pair of left and right work mounting seat surfaces 24 a of the carriage 20 which is projected from the upper cover 4 of the housing 1 and exposed, and is fixed with a bolt. Now, it is assumed that the carriage 20 is stopped at a position close to the motor bracket 6 in FIG.

In this state, the AC servomotor 40, which is a drive device, is rotated in the normal direction. When the AC servomotor 40 normally rotates in this manner, the rotational force thereof causes the ball screw shaft 31 of the ball screw device 30 to rotate normally. When the ball screw shaft 31 is rotated, the rotation of the ball screw shaft 31 is transmitted to the ball screw nut 32 via the ball 33 interposed between the spiral groove 31a of the ball screw shaft 31 and the spiral groove 32a of the ball screw nut 32. Then, the ball screw nut 32 responds to move in the axial direction. As a result, the carriage 20 fixed to the ball screw nut 32 moves together in the axial direction.

When the ball screw nut 32 moves, the steel balls move spirally while rolling in both ball screw grooves of the ball screw shaft 31 and the ball screw nut 32 facing each other. Further, since the ball screw device of this embodiment is of the end cap circulation type, after reaching the nut end, the ball screw device is returned to the original position through the curved path provided in the ball circulation member 35 and the ball return path provided in the nut body. Repeat the cycle back. Also, in the case of the tube circulation system, the balls roll in both spiral grooves facing each other and move in a spiral shape to make one and a half to three and a half turns in the spiral groove, and then the ball circulation tube in the nut. The ball is scooped up, and the land of the ball screw shaft 31 is obliquely climbed along the tube, and the circulation returning to the spiral groove is repeated.

As described above, since many balls made of hard steel roll in both spiral grooves and repeat circulation in the ball screw nut 32, the ball screw nut of the ball screw device 30 is in operation. It is unavoidable that continuous noise is generated at the portion 32. The noise blocking will be described later. The carriage 20 is supported on the left and right sides by the sliders 12 of the pair of left and right linear motion guide devices 10. Then, as the carriage 20 moves, the slider 12 moves along the guide rail 11 of the linear motion guide device 10. That is, the movement of the carriage 20 is guided to the guide rail 11 via the movement of the slider 12 of the linear motion guide device 10. In this way, the smooth movement of the carriage 20 is hindered, so that an accurate linear movement of the workpiece mounted on the carriage 20 is ensured.

When the slider 12 moves, a large number of steel rolling elements 18 move while rolling in the rolling element rolling grooves 13 of the guide rail 11 and the rolling element rolling grooves 16 of the slider 12. Suru Then, a U-turn is made on the curved path provided at one end of the slider 12, and the other end of the slider 12 is reached through the circulation path 17 formed in the slider sleeve portion 15, and then at the curved path provided there. Is reversely U-turned and returns to the opposite rolling element rolling grooves 13 and 16 again to repeat the circulation.

As described above, a large number of rolling elements 18 made of hard steel roll in the rolling element rolling grooves 13 and 16 and repeat the circulation in the slider 12, so that the linear motion guide device is operated during operation. Even at the 10 slider 12 portion, continuous noise is still generated. The interception of those noises is as follows. In the present embodiment, the continuous noise generated in the portion of the slider 12 of the linear motion guide device 10 and the portion of the ball screw nut 32 of the ball screw device 30 described above causes the sponge attached to the lower surface of the upper cover 4. It is absorbed by the sound absorbing material 70 in the shape of a circle. Further, as will be described later, by sealing the slit S, which is the only opening of the closed housing 1, with the seal band 60, noise is prevented from leaking out of the housing 1. In this case, the sound absorbing material 70 is disposed immediately above the ball screw nut 32 of the ball screw device 30 in which noise is most likely to be generated, thereby enhancing the effect of noise prevention. As a structure for holding the sound absorbing material 70, since a pair of left and right protrusions 4b, 4b having an L-shaped cross section are provided over the entire length of the lower surface of the upper cover 4, the rigidity of the cover 4 is improved. is there.

In this way, when the carriage 20 is driven by the drive device 40 via the ball screw device 30 and moves in the housing 1 in the axial direction while being guided by the linear motion guide device 10, from the surface of the upper cover 4. The protrusion 24 of the carriage to which the protruding work is attached moves axially within the opening of the slit S. Along with the movement of the convex portion 24 of the carriage, the seal band 60 whose end is locked to the convex portion 24 and which forms a loop also moves. For example, when the carriage 20 moves to the right in FIG. 2, the seal band 60 is diverted from the traveling pulley 50c to the pulley 50d, and vice versa from the opposite end pulley 50b to the pulley 50a. And move clockwise while rotating in FIG. In this rotation, the guide plate 63 attached to the lower portion of the seal band 60 moves inside the through hole 7a of the housing body 2 in the direction opposite to the traveling direction of the carriage 20. The moving distance of the guide plate 63 is the same as the stroke length of the carriage 20, and there is no risk of collision with the end cover 5 and the motor bracket 6 at the end.

Since there is a slight gap between the guide plate 63 and the inner wall of the through hole 7a, the guide plate 63 can effectively prevent the lateral displacement of the loop of the elongated seal band 60. Thus, the loop of the seal band 60 seals the opening of the slit S of the housing 1 in the movement range of the workpiece mounting seat surface 24a of the carriage 20 while rotating with the movement of the carriage 20 in a very stable state. The sealing is performed by engaging both side edges of the seal band 60 with the groove 3a on the end surface of the side cover 3 and the groove 4a on the end surface of the upper cover 4, respectively. Therefore, the inside and the outside of the housing 1 are communicated with each other through the extremely narrow and U-shaped bent gap that is interposed between the seal band 60 and the side cover 3 and the upper cover 4 to prevent dust. It is possible to effectively prevent the intrusion of fine foreign matters such as the above, and to effectively block the leakage of noise generated from the linear motion guide device 10 and the ball screw device 30.

The linear motion actuator of this embodiment is a linear motion actuator for transporting a large and heavy work, and in order to transport such a work at a high speed and position it with high accuracy, High rigidity is required for the actuator. In particular, since the carriage that connects the work and the linear motion guide is a member that directly receives the load of the work, it is an important factor that determines the rigidity of the linear motion actuator. Therefore, in the present embodiment, the intention is particularly to make the structure suitable for increasing the rigidity of the linear motion actuator.

One of them is that a large number of through holes 7 in the axial direction are provided in the thick portion of the bottom of the housing body 2 to form a hollow structure. This makes it lightweight and highly rigid. Secondly, the work mounting seat surface 24a on which the work weight is directly loaded on the carriage 20 is formed so as to be located right above the guide rail 11 of the linear motion guide device 10. As a result, the work weight applied to the work mounting seat surface 24a can be supported on the axis of the linear motion guide device 10 which is most advantageous in terms of rigidity, and as a result, the thickness of the carriage 20 can be made thin and lightweight. The realization of both high efficiency and substantially high rigidity of the linear motion actuator.

Thirdly, as a dust-proof structure for sealing the opening of the slit S on the upper surface of the housing 1 required for the movement of the carriage 20, a movable seal band skillfully and effectively utilizing the through hole 7a provided in the housing body 2 is used. 60 is used. That is, the seal band 60 is looped and its end is locked to the carriage 20, and the seal band 60 is circularly moved along with the movement of the carriage 20 through the through hole 7a. It is much simpler than. As a result, the rigidity of the carriage 20 can be increased and the size can be reduced.

FIG. 5 shows another embodiment. The dust-proof structure of the linear motion actuator of this embodiment is suitable for a linear motion actuator for a relatively light load application. The housing 1 is a box-shaped body in which a bottom portion, a side surface portion, and an upper surface portion are integrally extruded and is long in the axial direction, and an axial slit S is opened in the upper surface portion. In the center of the floor surface, a shallow groove 80 that extends in the axial direction and serves as a passage for the seal band 60 is formed.

A guide rail 11 of the linear motion guide device 10 is provided on the floor surface of the housing 1. The guide rail 11 has a concave shape with an open upper side, and a pair of left and right ball rolling grooves 13 extending in the axial direction are formed on the inner surfaces facing each other. A ball screw nut 32 of a ball screw device 30 is fitted in the guide rail 11 having a concave shape so as to be movable in the axial direction. In this case, the ball screw nut 32 also serves as the slider 12 of the linear motion guide device 10.

That is, ball rolling grooves (not shown) are formed on both the left and right side surfaces of the ball screw nut 32 so as to face the ball rolling grooves 13 of the guide rail 11. A ball screw nut 32 is fitted to the guide rail 11 via a large number of balls (not shown) rolling in the ball rolling path. In addition, a ball circulation path formed of a through hole parallel to the ball rolling groove on the outer surface is formed in the thick portion on the inner side of both the left and right outer surfaces of the ball screw nut 32. Further, a curved ball groove that connects the ball rolling groove on the outer surface and the ball circulation path is provided on an end cap 32E fixed to the front and rear end surfaces of the ball screw nut 32 with bolts 32B. An infinite ball circulation path is formed by the ball rolling groove, the ball circulation path, and the curved ball groove, and the ball screw nut 32 is rotated through the rolling of a large number of balls rotatably mounted in the infinite ball circulation path. Is guided by the guide rail 11 and smoothly moves straight.

The ball screw shaft 31 to which the ball screw nut 32 is screwed via a ball is rotatably supported by a bearing by an end cover (not shown) at the end of the housing 1 and a motor bracket. And is driven to rotate by the drive motor. Accordingly, the ball screw nut 32 linearly moves in the axial direction. In the carriage 20 attached to the ball screw nut 32, a top plate 21 projects out of the housing 1 via a neck portion 20A having a width narrower than the opening width of the slit S of the housing 1.

The dustproof device has only one seal band 60, and its end portion is locked to the end portion of the neck portion 20A of the carriage 20 to form a loop. At the end of the housing 1, four pulleys are arranged as in the case of the first embodiment, and the loop of the seal band 60 suspended on these four pulleys is moved to move the carriage 20. Together with this, the opening of the slit S is sealed by rotating it. The lower part of the loop is housed in the groove 80 on the floor of the housing 1, but the guide plate 63 shown in the first embodiment is unnecessary in this embodiment where the length of the housing 1 is short. Yes, not installed.

In the opening of the slit S, both side edges of the seal band 60 are engaged with the groove 1a formed on the opening end surface of the slit S to enhance the sealing performance. According to this embodiment, the work weight loaded on the workpiece mounting seat surface 24a of the carriage 20 is supported on the axis of the linear motion guide device 10 which is the most advantageous in terms of rigidity as in the first embodiment. In addition, since the carriage 20 is not provided with a cavity through which the seal band 60 is passed, high rigidity of the linear motion actuator is ensured.

Further, in addition to the linear motion guide device 10 and the ball screw device 30 provided in the housing 1, there is only one set of dustproof structure such as a dustproof seal band 60 and a pulley for supporting the sealband 60. Since the ball screw nut 32 of the screw device 30 also serves as the slider of the linear motion guide device 10, there is an advantage that the entire device can be made extremely small and lightweight.

In each of the above embodiments, the seal band 60 is a flat band made of polyurethane-impregnated canvas, but the present invention is not limited to this, and a steel band or a plastic band is used. be able to. In addition, for example, a ventilation device such as a small blower is attached to the motor bracket 6 at the end of the housing, and air is forcedly forced into the housing 1 to make the internal pressure of the actuator higher than the outside and to further invade dust. Can be prevented. On the other hand, the air inside the actuator is discharged to the outside, and the inside of the actuator is set to a negative pressure, so that a fine dust-free actuator such as metal fine particles or lubricant fine particles inside the actuator can be used. You can also do it. In these cases, according to each of the above-described embodiments, the opening area of the housing is very small, so that the required air amount can be extremely reduced.

Further, in each of the above embodiments, the ball screw nut 32 is shown to have a square outer shape, but the present invention is not limited to this, and it may be formed into a cylindrical shape or the like.

[0061]

[Effect of device]

 As described above, according to the present invention, the housing elongated in the axial direction, the linear motion guide device provided in the housing, and the housing movably in the axial direction via the linear motion guide device. And a drive device that drives the carriage in the axial direction via a ball screw, and a slit that is long in the moving direction of the carriage is provided on one surface of the housing. In a linear actuator that has a workpiece mounting seat surface that penetrates through the slit and projects to the outside of the housing, place pulleys on both ends of the housing in the axial direction, and attach one end of the seal band to the carriage. Fixed to one end side, the other end of the seal band is folded back at one end of the housing through the pulley and reaches the other end of the housing. Fixed to the other end of the carriage is folded through over Li to form a movable loop Sea Rubando, has a structure which seals the opening of the slit in the mobile loop of the seal band. Therefore, it is not necessary to pass a seal band inside the carriage, and therefore the carriage can be a solid and simple structure with high rigidity, can be easily downsized, and has high rigidity as a whole. The effect is that a small and lightweight linear motion actuator with a dustproof device can be provided.

[Submission date] June 2, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content] [Detailed description of the device]

[0001]

[Industrial applications]

This invention relates to an improvement in dustproof structure of the linear actuator have a carriage that is linearly driven built-axially to the housing.

[0002]

[Prior art]

 Examples of this type of actuator include those shown in FIGS. 6 and 7. In this system, a pair of parallel linear guide devices (linear guide devices) 102 are arranged on an elongated base 101, a carriage 105 is fixedly attached to a slider 104 which linearly moves on a guide rail 103, and a carriage for the carriage 105. 105 is connected to a ball nut 107 of a ball screw device 106 which is a rotation-linear conversion drive mechanism. Then, by rotating the ball screw shaft 109 by the AC servo motor 108, the carriage 105 is linearly moved in the axial direction along the guide rail 103. The work W, which is a driven body, is fixed to the work mounting seat surfaces 110 on both sides of the carriage 105 by screws, and the linear movement and the precision positioning operation are repeated with high accuracy.

In the above actuator, most of the outer circumference is covered with a side cover 111, an upper cover 112, an end face cover 113, and the like to ensure safety and aesthetics, and to secure precision parts such as a linear guide device 102 and a ball screw device 106. We are trying to prevent dust. However, since the workpiece mounting seat surface 110 of the carriage 105 must be exposed to the outside, an axial gap (slit) S between the side cover 111 and the upper cover 112 over the entire length of the moving range L of the carriage 105. Is open. Therefore, dust and the like enter and exit through the opening of the slit S, which is not perfect in terms of dust prevention.

On the other hand, conventionally, for example, a linear motion actuator in which a slit opening in a moving range of a carriage is covered with a movable belt has been proposed as disclosed in Japanese Utility Model Application Laid-Open No. 4-60642 by the present applicant. There is. As shown in FIGS. 8 and 9, a carriage 121 is mounted on a cylinder tube 120 having a long axial slit S on one side surface (upper surface) slidably in the axial direction. Is connected to a ball nut 124 screwed to a screw shaft 123 of a ball screwing device 122, and is linearly driven in the axial direction by an AC servomotor 125.

A table body 126 is projectingly provided on the upper portion of the carriage 121, penetrates the slit S and is exposed to the outside of the cylinder tube 120, and the upper surface of the table body has mounting bolt holes 127 at four corners. It is a surface 128. As shown in FIG. 9, an insertion hole 130 for the screw shaft 123 is formed in the carriage 121 in the axial direction, and a nut accommodating space 131 for accommodating the feed ball nut 124 is formed in the center of the insertion hole 130. Has been done. The nut storage space 131 is provided with a square groove 131a at the center of its ceiling, and is open downwardly. In the nut storage space 131, a ball nut 124 having a square anti-rotation projection 132 is incorporated by fitting the projection 132 into the square groove 131a.

The left and right sides of the carriage 121 are each projected in a V shape, and they are fitted to the inner surface of the rhombus inside the cylinder tube 120 via sliding members (not shown) attached to both outer edges thereof. The table body 126 projecting from the carriage 121 has a band insertion hole 136 through which the seal band 135 is inserted. The band insertion hole 136 has a band guide surface 137 formed in a gentle mountain shape that curves in an upward warp, and opens in the front and rear of the lower surface of the table body. A thin steel seal band 135 is inserted through the opening and inserted into the band insertion hole 136.

After the carriage 121 is assembled in the cylinder tube 120, the opening of the slit S on the upper surface of the cylinder tube 120 is covered with the above-mentioned seal band 135. A strip-shaped rubber magnet is attached along the opening side edge of the slit S, and its magnetic force attracts the seal band 135 to enhance the sealing performance. Both ends of the seal band 135 are fixed to the end cap 140 and the head cap 141, respectively, and the middle part of the seal band 135 is placed on the curved band guide surface 137 of the carriage 121.

Now, when the AC servomotor 125 is driven in forward / reverse rotation, the screw shaft 123 rotates accordingly, and the ball nut 124 moves in the front / rear direction. As a result, the carriage 121 is moved forward and backward while being guided by the cylinder tube 120, and the work attached to the work mounting seat surface 128 of the table 126 is arbitrarily moved in the axial direction of the linear motion table device to a predetermined position. Can be stopped exactly.

At this time, the seal band 135 prevents dust from entering the inside through the slit S of the cylinder tube 120. The table body 126 moves while pushing up the seal band 135 by the curved surface of the band guide surface 137 during its movement.

[0010]

[Problems to be solved by the device]

 However, in the above-mentioned conventional example in which the slit S of the cylinder tube 120 is closed by the seal band 135, while the high dustproof effect is obtained, the following problems occur. Since the seal band 135 is passed through the carriage 121, the carriage structure is complicated and the rigidity of the carriage 121 cannot be increased.

Since the band insertion hole 136 is provided so as to penetrate through the central portion of the table body 126 provided on the carriage 121, the position of the mounting bolt hole 127 of the work mounting seat surface 128 is advantageous in terms of rigidity in the central portion. However, the carriage 121 becomes large in size because it cannot be provided at the four corners and must be arranged at four corners. By the way, in the case of a large class linear motion actuator with a large load capacity, it is most important to have high rigidity in order to convey the work at high speed and to position it with high accuracy. The carriage of the linear motion actuator is a member that connects the linear motion guide part and the work, and is one of the important factors that determine the rigidity of the linear motion actuator, and there is no structure that cannot increase the rigidity. Appropriate.

[0012] Therefore, the present invention has been made by paying attention to the dust-proof structure of the above-mentioned conventional linear motion actuator. A seal band for sealing a slit for allowing the carriage to move in the axial direction is provided on the outside of the carriage. It is an object of the present invention to solve the above-mentioned conventional problems by providing a dustproof structure that is movable in the axial direction in cooperation with mounting, a seal band and a carriage.

[0013]

[Means for Solving the Problems]

 To achieve the above object, the present invention provides a housing which is long in the axial direction, a linear motion guide device provided in the housing, and a housing which is axially movable through the linear motion guide device. The carriage is provided with a drive device that drives the carriage in the axial direction via a ball screw. A slit that is long in the moving direction of the carriage is provided on one surface of the housing. In a linear actuator that has a workpiece mounting seat surface that penetrates and projects to the outside of the housing, place pulleys on both axial ends of the housing and fix one end of the seal band to one end of the carriage. Then, fold the other end of the seal band through the pulley and fold it back at one end of the housing. Forming a movable loop seal band are fixed to the other end of the Yarijji In addition, the guide means prevents lateral displacement of the seal band. The dust-proof structure is characterized in that the opening of the slit is sealed by a movable loop of the seal band.

Here, the main body of the housing may be an extruded product to form hollow holes or grooves in the axial direction, and the lower part of the movable loop of the seal band may be passed through these holes or grooves. . In addition, a concave groove that engages with the side edge of the seal band can be formed in the side edge portion of the slit opened on one surface of the housing.

Further, a guide plate is attached to a lower part of the movable loop of the seal band which is passed through the hollow hole or groove of the main body of the housing, and the guide plate is engaged with the hollow hole or groove. Can be made. Further, a pair of protrusions having an L-shaped cross section and facing each other may be provided on the inner surface of the cover that covers the upper surface of the housing, and the sound absorbing material may be attached between these protrusions.

[0016]

[Action]

 The dust-proof structure of the linear actuator of this invention has pulleys at both ends of the housing in the axial direction, the seal band is fixed to one end of the carriage, and is folded back through the pulley to move the seal loop. And the other end of the band was fixed to the other end of the carriage. The loop of the seal band is integrated with the carriage that linearly moves back and forth in the axial direction, and circulates and reciprocates in the axial direction to seal the opening of the slit. Therefore, it is not necessary to pass the seal band inside the carriage, and therefore the carriage can be solid and have a simple structure and high rigidity, and can be easily miniaturized.

In addition, the hollow structure for achieving both high rigidity and light weight of the housing can be effectively used by passing the lower part of the movable loop of the seal band through the hollow hole or groove formed in the housing. . Further, if a concave groove that engages with the side edge of the seal band is formed in the side edge portion of the slit of the housing, the sealing action of the seal band is promoted and the dustproof and soundproof effect is increased.

If a guide plate is attached to the lower part of the movable loop of the seal band, stable running of the seal band can be ensured even with a large actuator having a long seal band. Also, if a pair of protrusions having an L-shaped cross section are provided on the inner surface of the cover that covers the upper surface of the housing, and a sound absorbing material is attached between these protrusions, the rigidity of the cover can be increased and at the same time, the sound insulation performance can be improved. Can be improved.

[0019]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention, FIG. 1 is a transverse sectional view of a linear actuator, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a front view showing a cutaway view of a part of the linear guide device.

In the linear motion actuator of this embodiment, a linear motion guide device (linear guide device) 10 is provided in a housing 1 which is long in the axial direction, and moves linearly through the linear motion guide device 10. A carriage 20 freely attached is provided. Further, in order to accurately convey the carriage 20 in the axial direction at a selected speed to a selected position, a drive device 40 for driving the carriage 20 in the axial direction via a ball screw device 30 is provided.

The housing 1 is provided with a slit S that is long in the moving direction of the carriage 20 on the upper surface, and the carriage 20 has a work mounting seat surface 24 a that penetrates the slit S and projects to the outside of the housing 1. ing. The dustproof structure of the linear actuator having such a structure is as follows. Pulleys 50 are arranged at both ends of the housing 1 in the axial direction, and one end of the seal band 60 is fixed to one end of the carriage 20. The pulley 50 is folded back at one end of the housing 1 to reach the other end of the housing 1. It is folded back through another pulley 50 and fixed to the other end of the carriage 1 to form a movable loop of the seal band 60, and the opening of the slit S is closed by the movable loop of the seal band 60.

A more detailed description will be given below. The housing 1 includes a housing main body 2, a pair of left and right side covers 3 and 3, an upper cover 4, an end cover 5 that has a bearing built in and covers one end, and a motor bracket 6 that has a bearing built in and covers the other end. It consists of In the case of this embodiment, the housing body 2 is an extruded product made of aluminum and has a substantially chevron cross-section with an open upper part. The bottom of the housing main body 2 to which a load is applied is required to have rigidity so that it is not deformed under the influence of the load and the accuracy of conveyance of the linear motion actuator is deteriorated. In this embodiment, the bottom wall of the housing body 2 has a hollow structure having a large number of through holes 7 in the axial direction to ensure both rigidity and weight reduction.

A step portion 8 extending over the entire length is formed symmetrically on the left and right sides of the floor surface of the housing body 2, and a pair of left and right straight portions are formed on the floor surface of the left and right step portions 8. The guide rails 11 of the dynamic guide device 10 are fixed by bolts (not shown). A slider 12 is movably mounted on the guide rail 11 along the rail. In this embodiment, two sliders 12 are arranged for each guide rail 11.

Here, a schematic structure of the linear motion guide device 10 will be described. As shown in an enlarged view in FIG. 4, the guide rail 11 has a rectangular cross section and is formed on both left and right side surfaces thereof so as to extend in the axial direction. It has a rolling element rolling groove 13. The slider 12 has a U-shaped cross section including an upper plate portion 14 and sleeve portions 15 extending downward from both side portions thereof, and the left and right inner side surfaces of the sleeve portions 15 have rolling element rolling grooves of the guide rail 11. A rolling element rolling groove 16 is formed at a position opposed to 13. Further, a circulation path 17 is formed in the sleeve portion 15 so as to communicate with the rolling element rolling grooves 13 and 16, and the rolling path and the circulating path 17 formed by the rolling element rolling grooves 13 and 16 are formed. A large number of balls 18, which are rolling elements, are held by a cage 19 and are rotatably inserted. The guide rail 11 is provided with rail mounting bolt holes 11a at a plurality of positions at intervals in the length direction, and mounting slider bolt holes 12a are provided at four corners on the upper surface of the slider 12.

The carriage 20 has a top plate 21 having a width slightly smaller than the inner width of the housing 1 and a length of about two slides 12, and a ball formed so as to protrude downward from the lower surface thereof. And a nut mounting body portion 22. Then, both the left and right sides of the top plate 21 are placed on the upper surfaces of the sliders 12 of the left and right linear motion guide devices 10, and fixed by the mounting bolts 27 screwed into the bolt holes 12a, so that the four sliders 12 are mounted. It is supported and is installed in the housing 1 so as to be movable in the axial direction.

On the upper surface of the top plate 21, a concave groove 23 is formed in the central portion over the entire length, and convex portions 24 extending over substantially the entire length are formed on both left and right sides of the concave groove 23. The upper surfaces 24a of the protrusions 24 are work mounting seat surfaces that are slightly higher than the upper cover 4 and project outward. Further, stepped portions 24b lower than the work mounting seat surface 24a are formed at both ends of the convex portion 24 in the length direction.

The protrusions 24 are formed such that the left and right protrusions 24 are located right above the guide rails 11 of the left and right linear motion guide devices 10, respectively. This is to make the thickness of the carriage top plate 21 as thin as possible by arranging the work mounting surface 24a of the carriage 20 on the axis of the linear motion guide device 10 which is most advantageous in terms of rigidity. Is.

The ball screw device 30 includes a ball screw shaft 31 and a ball screw nut 32. The ball screw shaft 31 has a spiral groove on the outer peripheral surface, one end is supported by the end cover 5 via a bearing, and the other end is supported by the motor bracket 6 via a bearing. It is arranged in the center of the width of the housing 1 in parallel with the rail 11. One shaft end of the ball screw shaft 31 supported by the motor bracket 6 projects outward from the motor bracket 6 and is connected to the output shaft of the drive motor 40.

The ball screw nut 32 has a spiral groove facing the spiral groove of the ball screw shaft 31 on its inner peripheral surface, and the ball screw shaft 31 is rotated through a large number of balls rolling in both spiral grooves facing each other. It is screwed to. The ball screw nut 32 of this embodiment is, for example, an end cap circulation system, and ball circulation members (end caps) 35 are detachably joined to both end surfaces of the nut. In addition, a ball return passage formed of an axial through hole is provided in the thick portion of the nut body. The ball circulation member 35 is provided with a curved path on the end surface on the side where it is joined to the nut body, which connects the opposing spiral grooves and the ball return path.

When the ball screw shaft 31 and the ball screw nut 32 rotate relative to each other, a steel ball advances while rolling in both ball screw grooves of the ball screw shaft 31 and the ball screw nut 32 facing each other. Circulation returning to the original position is repeated through a curved path provided in the ball circulating member 35 at the end and a ball return path provided in the nut body.

However, the ball screw nut 32 is not limited to the end cap circulation type, and may be a tube circulation type or a top type. In the case of the tube circulation system, a U-shaped ball circulation tube is installed above the nut body as a ball circulation path for guiding and circulating the balls. The ball rolls in the opposite spiral grooves and is scooped up by the rear ball circulation tube, diagonally rides over the land portion of the ball screw shaft 31 along the tube and returns to the spiral groove again to infinitely circulate. It has a circular structure.

In the case of the top type, a top having a ball circulation groove is fitted in the thick part of the nut body, and the ball obliquely crosses over the land portion of the spiral groove of the ball screw shaft 31 along the top groove. It is a circulation system that returns between both spiral grooves facing each other. In this embodiment, as the drive unit 40, an AC servomotor is fixed to the outer surface of the motor bracket 6 with bolts. The output shaft of the AC servomotor 40 is connected to a ball screw shaft 31 rotatably supported in the housing 1 via a bearing via a coupling ring 39.

The ball screw nut 32, which is screwed to the ball screw shaft 31 via a ball, is fitted and fixed to the ball screw nut mounting body portion 22 of the carriage 20 so that the carriage 20 and the ball screw device 30 are connected to each other. Are connected. The carriage 20 needs to be moved in the axial direction in conjunction with the operation of the ball screw device 30 by the AC servomotor 40 and the ball screw nut 32. Therefore, a slit S is provided between the side cover 3 and the upper cover 4 as a passage for the convex portion 24 of the carriage 20 with a space therebetween. In this case, the slits S are provided in a pair of left and right corresponding to the pair of left and right convex portions 24 of the carriage 20.

The side cover 3 and the upper cover 4 forming the opening of the slit S are both extruded products made of aluminum, and the opposite end faces of a little thickness are Guide grooves 3a and 4a as guide means of the seal band are formed respectively. In addition, a pair of left and right protrusions 4b having an L-shaped cross section are provided in the central portion of the lower surface of the upper cover 4 so as to face each other with a space therebetween. The facing distance is set to a size corresponding to the width of the ball screw nut 32 of the ball screw device 30. A sponge-like sound absorbing material 70 is fitted in a space surrounded by the protrusions 4b and 4b and the lower surface of the upper cover.

Although not shown, for example, a permanent magnet is fixed to the lower surface side of the carriage 20, while a proximity switch such as a Hall element facing the permanent magnet is attached to the inner surface of the housing body 2. The proximity switch and the permanent magnet detect the origin position of the carriage 20 in the direction of the linear movement axis, and by controlling the rotation of the AC servomotor 40, which is a drive unit, based on the origin detection signal, the position of the linear movement is detected. It is configured so that the decision can be made with high accuracy.

Although not shown, a contact position detector such as a limit switch for preventing overrun of the carriage 20 may be installed at the end of the housing 1. In that case, the wiring of the limit switch is Alternatively, it may be housed in a groove 2A provided on the outer side surface of the housing body 2 so as not to get in the way. In the linear actuator having the above structure, the housing 1 has a substantially sealed structure except for the opening of the slit S, and dust is prevented by closing the opening of the slit S with a movable seal band 60.

Since the left and right slits S have basically the same seal structure, only one side will be described and the other side will be omitted. Pulleys 50 for guiding the seal band 60 are arranged at four corners of the housing 1 as shown in FIG. That is, the pulley 50a at the upper corner of the motor bracket 6 is attached to the extended position of the slit S. The pulley 50b at the lower corner of the same motor bracket 6 is mounted directly under the pulley 50a. Further, the pulley 50c at the upper corner of the end cover 5 at the opposite end is attached to the extension position of the slit S. A pulley 50d at the lower corner of the same end cover 5 is attached directly under the pulley 50c.

The seal band 60 hung around the pulleys 50 at four positions is a flat band made of polyurethane-impregnated canvas, one end of which is fixed to the step portion 24 b provided on one end side of the carriage 20 with a set screw 61. Are locked. The other end of the seal band 60 is similarly fixed and locked to the step portion 24b provided on the other end side of the carriage 20 by a set screw 61. As a result, a loop of the seal band 60 that extends from one end of the carriage 20 to the other end of the carriage 20 via the pulley 50a, the pulley 50b, the pulley 50c, and the pulley 50d is formed.

At the opening of the slit S, both side edges of the seal band 60 are inserted into the groove 3a on the end surface of the side cover 3 and the groove 4a on the end surface of the upper cover 4 to enhance the sealing performance and effectively seal. In addition, the seal band 60 is prevented from being displaced laterally . Further, the lower portion of the loop of the seal band 60, that is, the portion between the pulley 50b at the lower corner of the motor bracket 6 and the pulley 50d at the lower corner of the end cover 5 is arranged so that the housing body 2 is axially moved. Among the plurality of through-holes 7 passing through, the through-hole 7a immediately below the guide rail 11 of the linear guide device 10 is passed through. Then, the rectangular guide plate 63 is fixedly attached at a position just in the middle of the loop of the seal band 60, that is, a position directly below the carriage 20 when the carriage 20 is located at the center of the housing 1 in the axial direction. is there. A slight gap is maintained between the side surface of the guide plate 63 and the inner wall of the through hole 7a so as to prevent the seal band 60 from lateral displacement.

The operation of locking the end portion of the seal band 60 to the step portion 24 b of the carriage 20 is performed after the carriage 20 is assembled to the slider 12 of the linear motion guide device 10, and the loop of the seal band 60 is formed. It After that, the side cover 3 and the upper cover 4 are attached. Next, the operation of the above embodiment will be described.

First, a work (not shown), which is a to-be-conveyed object, is attached to the pair of left and right work mounting seat surfaces 24 a of the carriage 20 which is projected from the upper cover 4 of the housing 1 and exposed, and is fixed with a bolt. Now, it is assumed that the carriage 20 is stopped at a position close to the motor bracket 6 in FIG.

In this state, the AC servomotor 40, which is a drive device, is rotated in the normal direction. When the AC servomotor 40 normally rotates in this manner, the rotational force thereof causes the ball screw shaft 31 of the ball screw device 30 to rotate normally. When the ball screw shaft 31 is rotated, the rotation of the ball screw shaft 31 is transmitted to the ball screw nut 32 via the ball 33 interposed between the spiral groove 31a of the ball screw shaft 31 and the spiral groove 32a of the ball screw nut 32. Then, the ball screw nut 32 responds to move in the axial direction. As a result, the carriage 20 fixed to the ball screw nut 32 moves together in the axial direction.

When the ball screw nut 32 moves, the steel balls move spirally while rolling in both ball screw grooves of the ball screw shaft 31 and the ball screw nut 32 facing each other. Further, since the ball screw device of this embodiment is of the end cap circulation type, after reaching the nut end, the ball screw device is returned to the original position through the curved path provided in the ball circulation member 35 and the ball return path provided in the nut body. Repeat the cycle back. Also, in the case of the tube circulation system, the balls roll in both spiral grooves facing each other and move in a spiral shape to make one and a half to three and a half turns in the spiral groove, and then the ball circulation tube in the nut. The ball is scooped up, and the land of the ball screw shaft 31 is obliquely climbed along the tube, and the circulation returning to the spiral groove is repeated.

As described above, since many balls made of hard steel roll in both spiral grooves and repeat circulation in the ball screw nut 32, the ball screw nut of the ball screw device 30 is in operation. It is unavoidable that continuous noise is generated at the portion 32. The noise blocking will be described later. The carriage 20 is supported on the left and right sides by the sliders 12 of the pair of left and right linear motion guide devices 10. Then, as the carriage 20 moves, the slider 12 moves along the guide rail 11 of the linear motion guide device 10. That is, the movement of the carriage 20 is guided to the guide rail 11 via the movement of the slider 12 of the linear motion guide device 10. In this way, the smooth movement of the carriage 20 is hindered, so that an accurate linear movement of the workpiece mounted on the carriage 20 is ensured.

When the slider 12 moves, a large number of steel rolling elements 18 move while rolling in the rolling element rolling grooves 13 of the guide rail 11 and the rolling element rolling grooves 16 of the slider 12. Suru Then, a U-turn is made on the curved path provided at one end of the slider 12, and the other end of the slider 12 is reached through the circulation path 17 formed in the slider sleeve portion 15, and then at the curved path provided there. Is reversely U-turned and returns to the opposite rolling element rolling grooves 13 and 16 again to repeat the circulation.

As described above, a large number of rolling elements 18 made of hard steel roll in the rolling element rolling grooves 13 and 16 and repeat the circulation in the slider 12, so that the linear motion guide device is operated during operation. Even at the 10 slider 12 portion, continuous noise is still generated. The interception of those noises is as follows. In the present embodiment, the continuous noise generated in the portion of the slider 12 of the linear motion guide device 10 and the portion of the ball screw nut 32 of the ball screw device 30 described above causes the sponge attached to the lower surface of the upper cover 4. It is absorbed by the sound absorbing material 70 in the shape of a circle. Further, as will be described later, by sealing the slit S, which is the only opening of the closed housing 1, with the seal band 60, noise is prevented from leaking out of the housing 1. In this case, the sound absorbing material 70 is disposed immediately above the ball screw nut 32 of the ball screw device 30 in which noise is most likely to be generated, thereby enhancing the effect of noise prevention. As a structure for holding the sound absorbing material 70, since a pair of left and right protrusions 4b, 4b having an L-shaped cross section are provided over the entire length of the lower surface of the upper cover 4, the rigidity of the cover 4 is improved. is there.

In this way, when the carriage 20 is driven by the drive device 40 via the ball screw device 30 and moves in the housing 1 in the axial direction while being guided by the linear motion guide device 10, from the surface of the upper cover 4. The protrusion 24 of the carriage to which the protruding work is attached moves axially within the opening of the slit S. Along with the movement of the convex portion 24 of the carriage, the seal band 60 whose end is locked to the convex portion 24 and which forms a loop also moves. For example, when the carriage 20 moves to the right in FIG. 2, the seal band 60 is diverted from the traveling pulley 50c to the pulley 50d, and vice versa from the opposite end pulley 50b to the pulley 50a. And move clockwise while rotating in FIG. In this rotation, the guide plate 63 attached to the lower portion of the seal band 60 moves inside the through hole 7a of the housing body 2 in the direction opposite to the traveling direction of the carriage 20. The moving distance of the guide plate 63 is the same as the stroke length of the carriage 20, and there is no risk of collision with the end cover 5 and the motor bracket 6 at the end.

Since there is a slight gap between the guide plate 63 and the inner wall of the through hole 7a, the guide plate 63 can effectively prevent the lateral displacement of the loop of the elongated seal band 60. Thus, the loop of the seal band 60 seals the opening of the slit S of the housing 1 in the movement range of the workpiece mounting seat surface 24a of the carriage 20 while rotating with the movement of the carriage 20 in a very stable state. The sealing is performed by engaging both side edges of the seal band 60 with the groove 3a on the end surface of the side cover 3 and the groove 4a on the end surface of the upper cover 4, respectively. Thus, the internal and external of the housing 1, it will be in communication via a very narrow and the gap that is bent in a U-shape that is interposed between the sealing band 60 and the side cover 3 and the upper cover 4, the seal It is possible to prevent lateral displacement of the band 60, effectively prevent intrusion of fine foreign matter such as dust, and effectively block leakage of noise generated from the linear motion guide device 10 and the ball screw device 30. You can

The linear motion actuator of this embodiment is a linear motion actuator for transporting a large and heavy work, and in order to transport such a work at a high speed and position it with high accuracy, High rigidity is required for the actuator. In particular, since the carriage that connects the work and the linear motion guide is a member that directly receives the load of the work, it is an important factor that determines the rigidity of the linear motion actuator. Therefore, in the present embodiment, the intention is particularly to make the structure suitable for increasing the rigidity of the linear motion actuator.

One of them is that a large number of through holes 7 in the axial direction are provided in the thick portion of the bottom of the housing body 2 to form a hollow structure. This makes it lightweight and highly rigid. Secondly, the work mounting seat surface 24a on which the work weight is directly loaded on the carriage 20 is formed so as to be located right above the guide rail 11 of the linear motion guide device 10. As a result, the work weight applied to the work mounting seat surface 24a can be supported on the axis of the linear motion guide device 10 which is most advantageous in terms of rigidity, and as a result, the thickness of the carriage 20 can be made thin and lightweight. The realization of both high efficiency and substantially high rigidity of the linear motion actuator.

Thirdly, as a dust-proof structure for sealing the opening of the slit S on the upper surface of the housing 1 required for the movement of the carriage 20, a movable seal band skillfully and effectively utilizing the through hole 7a provided in the housing body 2 is used. 60 is used. That is, the seal band 60 is looped and its end is locked to the carriage 20, and the seal band 60 is circularly moved along with the movement of the carriage 20 through the through hole 7a. It is much simpler than. As a result, the rigidity of the carriage 20 can be increased and the size can be reduced.

FIG. 5 shows another embodiment. The dust-proof structure of the linear motion actuator of this embodiment is suitable for a linear motion actuator for a relatively light load application. The housing 1 is a box-shaped body in which a bottom portion, a side surface portion, and an upper surface portion are integrally extruded and is long in the axial direction, and an axial slit S is opened in the upper surface portion. In the center of the floor surface, a shallow groove 80 that extends in the axial direction and serves as a passage for the seal band 60 is formed.

A guide rail 11 of the linear motion guide device 10 is provided on the floor surface of the housing 1. The guide rail 11 has a concave shape with an open upper side, and a pair of left and right ball rolling grooves 13 extending in the axial direction are formed on the inner surfaces facing each other. A ball screw nut 32 of a ball screw device 30 is fitted in the guide rail 11 having a concave shape so as to be movable in the axial direction. In this case, the ball screw nut 32 also serves as the slider 12 of the linear motion guide device 10.

That is, ball rolling grooves (not shown) are formed on both the left and right side surfaces of the ball screw nut 32 so as to face the ball rolling grooves 13 of the guide rail 11. A ball screw nut 32 is fitted to the guide rail 11 via a large number of balls (not shown) rolling in the ball rolling path. In addition, a ball circulation path formed of a through hole parallel to the ball rolling groove on the outer surface is formed in the thick portion on the inner side of both the left and right outer surfaces of the ball screw nut 32. Further, a curved ball groove that connects the ball rolling groove on the outer surface and the ball circulation path is provided on an end cap 32E fixed to the front and rear end surfaces of the ball screw nut 32 with bolts 32B. An infinite ball circulation path is formed by the ball rolling groove, the ball circulation path, and the curved ball groove, and the ball screw nut 32 is rotated through the rolling of a large number of balls rotatably mounted in the infinite ball circulation path. Is guided by the guide rail 11 and smoothly moves straight.

The ball screw shaft 31 to which the ball screw nut 32 is screwed via a ball is rotatably supported by a bearing by an end cover (not shown) at the end of the housing 1 and a motor bracket. And is driven to rotate by the drive motor. Accordingly, the ball screw nut 32 linearly moves in the axial direction. In the carriage 20 attached to the ball screw nut 32, a top plate 21 projects out of the housing 1 via a neck portion 20A having a width narrower than the opening width of the slit S of the housing 1.

The dustproof device has only one seal band 60, and its end portion is locked to the end portion of the neck portion 20A of the carriage 20 to form a loop. At the end of the housing 1, four pulleys are arranged as in the case of the first embodiment, and the loop of the seal band 60 suspended on these four pulleys is moved to move the carriage 20. Together with this, the opening of the slit S is sealed by rotating it. The lower part of the loop is lateral displacement of Shiruban de housed in a groove 80 of the floor of the housing 1 is prevented, the guide plate 63 shown in the first embodiment, the length of the housings 1 Is not required in this embodiment and is not attached.

[0057] In the opening of the slit S is both side edges of the seal band 60, lateral displacement of the sea Rubando is prevented engages with the groove 1a as the guide means of the seal bands are formed at the open mouth end face of the slit S It also improves the sealing performance. According to this embodiment, the work weight loaded on the workpiece mounting seat surface 24a of the carriage 20 is supported on the axis of the linear motion guide device 10 which is the most advantageous in terms of rigidity as in the first embodiment. In addition, since the carriage 20 is not provided with a cavity through which the seal band 60 is passed, high rigidity of the linear motion actuator is ensured.

Further, in addition to the linear motion guide device 10 and the ball screw device 30 provided in the housing 1, there is only one set of dustproof structure such as a dustproof seal band 60 and a pulley for supporting the sealband 60. Since the ball screw nut 32 of the screw device 30 also serves as the slider of the linear motion guide device 10, there is an advantage that the entire device can be made extremely small and lightweight.

In each of the above embodiments, the seal band 60 is a flat band made of polyurethane-impregnated canvas, but the present invention is not limited to this, and a steel band or a plastic band is used. be able to. In addition, for example, a ventilation device such as a small blower is attached to the motor bracket 6 at the end of the housing, and air is forcedly forced into the housing 1 to make the internal pressure of the actuator higher than the outside and to further invade dust. Can be prevented. On the other hand, the air inside the actuator is discharged to the outside, and the inside of the actuator is set to a negative pressure, so that a fine dust-free actuator such as metal fine particles or lubricant fine particles inside the actuator can be used. You can also do it. In these cases, according to each of the above-described embodiments, the opening area of the housing is very small, so that the required air amount can be extremely reduced.

Further, in each of the above embodiments, the ball screw nut 32 is shown to have a square outer shape, but the present invention is not limited to this, and it may be formed into a cylindrical shape or the like.

[0061]

[Effect of device]

As described above, according to the present invention, the housing elongated in the axial direction, the linear motion guide device provided in the housing, and the housing movably in the axial direction via the linear motion guide device. And a drive device that drives the carriage in the axial direction via a ball screw, and a slit that is long in the moving direction of the carriage is provided on one surface of the housing. In a linear actuator that has a workpiece mounting seat surface that penetrates through the slit and projects to the outside of the housing, place pulleys on both ends of the housing in the axial direction, and attach one end of the seal band to the carriage. Fixed to one end side, the other end of the seal band is folded back at one end of the housing through the pulley and reaches the other end of the housing. Preventing lateral displacement of the seal band by the guide means to form the movable loop Sea Rubando and folded through over Li fixed to the other end of the carriage, sealing the opening of the slit in the mobile loop of the sealing band It was composed. Therefore, it is not necessary to pass a seal band inside the carriage. Therefore, the carriage can be made of a solid and simple structure with high rigidity, easy to miniaturize, and high rigidity as a whole. In addition, it is possible to provide a small and lightweight direct-acting actuator with a dustproof device.

[Brief description of drawings]

1 is a cross-sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a front view showing the linear guide device by cutting out a part thereof.

FIG. 5 is a cross-sectional view of another embodiment of the present invention.

FIG. 6 is a plan view showing an example of a conventional linear motion actuator.

FIG. 7 is a front view showing a part of FIG. 6 by cutting out.

FIG. 8 is a vertical cross-sectional view showing a dustproof structure of another conventional linear motion actuator.

9 is an enlarged perspective view of a main part of FIG.

[Explanation of symbols]

 1 Housing 10 Linear Motion Guide Device 20 Carriage 24a Workpiece Mounting Seat Surface 30 Ball Screw Device 40 Drive Device 50 Pulley 60 Seal Band S Slit

[Procedure amendment]

[Submission date] June 2, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of device] Dust-proof structure of linear actuator

[Scope of utility model registration request]

[Brief description of drawings]

1 is a cross-sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a front view showing the linear guide device by cutting out a part thereof.

FIG. 5 is a cross-sectional view of another embodiment of the present invention.

FIG. 6 is a plan view showing an example of a conventional linear motion actuator.

FIG. 7 is a front view showing a part of FIG. 6 by cutting out.

FIG. 8 is a vertical cross-sectional view showing a dustproof structure of another conventional linear motion actuator.

9 is an enlarged perspective view of a main part of FIG.

[Explanation of reference numerals] 1 housing 10 linear motion guide device 20 carriage 24a workpiece mounting seat surface 30 ball screw device 40 drive device 50 pulley 60 seal band S slit

Claims (1)

[Scope of utility model registration request] 1. A housing which is long in the axial direction, a linear motion guide device provided in the housing, a carriage disposed in the housing so as to be axially movable via the linear motion guide device, A drive device that drives the carriage in the axial direction via a ball screw, and a slit that is long in the moving direction of the carriage is provided on one surface of the housing.
In the linear actuator, wherein the carriage has a workpiece mounting seat surface that penetrates the slit and projects to the outside of the housing, pulleys are arranged at both ends of the housing in the axial direction, and one end of a seal band is attached to the carriage. The seal band is fixed to one end side of the carriage, and the other end of the seal band is folded back at one end of the housing through the pulley, reaches the other end of the housing and is further folded back through the pulley, is fixed to the other end side of the carriage, and the seal band is movable. A dust-proof structure for a linear actuator, wherein a loop is formed, and the opening of the slit is sealed by a movable loop of the seal band.