JP2002098211A - Linear actuator - Google Patents

Abstract

(57) Abstract: In a linear motion actuator in which an operation output section is driven forward and backward, the operation output section itself is linearly moved in a constant posture, and friction between relative movement sections is reduced to achieve high speed and high accuracy. To be able to move. The operation output section is an output sleeve (4) which is housed so as to be able to advance and retreat with respect to a fixed sleeve (3) and has a work mounting section at an output end, and an inner peripheral surface of the fixed sleeve (3). A flat portion extending in the longitudinal direction is formed at a plurality of locations and at positions facing each other in parallel with each other on the outer peripheral surface of the output sleeve (4), and between the fixed sleeve (3) and the output sleeve (4). A plurality of linear bearings including a plurality of rollers (30) interposed in a pre-pressed state between the opposing flat portions and a roller retainer (6) for rotatably holding these rollers. That you are.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-acting actuator, and more particularly to a direct-acting actuator in which an input shaft is driven to rotate by a drive unit and an output shaft interlocked with the input shaft is driven linearly.

[0002]

2. Description of the Related Art As this kind of linear actuator,
Japanese Patent Laid-Open No. 10-285867 has been proposed, which comprises a screw shaft connected to a rotation output shaft of a motor, a nut externally fitted to the screw shaft, and a cylindrical operating rod integral with the nut. And a fixed sleeve holding the operating rod movably via a ball bearing type linear bearing, and a movable table or the like that linearly moves in a fixed posture is connected to the tip of the operating rod. Thus, the operating rod is linearly driven by the screw pair of the screw shaft and the nut according to the rotation of the motor.

At this time, the operating rod is rotatable with respect to the fixed sleeve. However, since the operating rod R is connected to a movable table whose movement posture is regulated so as to move linearly, the nut is screwed. The rotation of the screw shaft is converted into a linear movement of the operating rod without rotating together with the rotation of the shaft. Furthermore, since a ball bearing type linear bearing is interposed between the linear rod and the fixed sleeve, the movement resistance of this part is small and the rotational output of the motor is smoothly converted to linear movement of the linear rod. You.

However, in this conventional device, in order to prevent co-rotation between the linear motion rod and the screw shaft, the driven portion to be mounted on the linear motion rod is regulated so as to move linearly. This is indispensable, and there is a problem that this linear motion rod cannot be used as an operation output unit that reciprocates in a fixed posture as it is. In order to solve this problem, it is conceivable to hold the linear motion rod in a detent state by a fixed sleeve, but in this case, the sliding resistance in the holding part for the detent remains as another problem. .

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for driving an operation output section with respect to the fixed sleeve (3) by rotating a screw shaft (1) coaxial with the fixed sleeve (3). It is an object of the present invention to provide a "linear motion actuator" in which the operation output unit itself is linearly moved in a precise and accurate posture, and at the same time, the friction of each part of the relative movement is reduced to enable high-speed movement.

[0006]

Means for Solving the Problems * 1 The technical means of the present invention for solving the above-mentioned problem is as follows: "The operation output portion is an output sleeve (3) accommodated in a movable manner with respect to the fixed sleeve (3). 4) and said fixed sleeve (3)
A flat portion extending in the longitudinal direction is formed at a plurality of locations and at positions opposed to each other in parallel with each other on the inner peripheral surface of the output sleeve (4) and the outer peripheral surface of the output sleeve (4). Between the fixed sleeve (3) and the output sleeve (4), a plurality of rollers (30) interposed in a pre-pressed state between the opposing flat portions, and these rollers. And a plurality of linear motion bearings comprising a roller retainer (6) for rotatably holding. "

The above technical means operates as follows. According to the above means, a plurality of linear motion bearings are interposed between the output sleeve (4) and the fixed sleeve (3) at positions corresponding to the respective sides of the polygonal cross section between the flat portions facing each other. Because
The output sleeve (4) and the fixed sleeve (3) relatively linearly move, but do not rotate (smooth-even relationship). Therefore, when the screw shaft (1) is driven to rotate, the output sleeve (4) is linearly moved in a constant posture in accordance with the direction of the rotation, and the work attached to the output sleeve (4) responds to the rotation. Is moved linearly. The rotation of the screw shaft (1) generates a rotational torque on the output sleeve (4),
This is supported by the roller (30) which is in a pre-pressed state between the flat portions facing the fixed sleeve (3),
The output sleeve (4) does not rattle in the rotational direction due to transmission from the screw shaft (1).

* 2. In the above item 1, "the screw groove formed on the inner peripheral surface of the output sleeve (4) is provided between the inner peripheral surface of the output sleeve (4) and the screw shaft (1). 41), a screw groove (11) formed on the outer peripheral surface of the screw shaft (1), and a ball screw including a plurality of balls (10) inserted in a preloaded state between the screw grooves. The output sleeve (4) is fixed with the rotation of the screw shaft (1) by the action of the ball screw.
It moves linearly with respect to (3). The relative movement between the output sleeve (4) and the screw shaft (1) is accompanied by the rolling of the ball (10) held between the screw grooves (41) and (11).

Accordingly, the linear motion bearing between the outer peripheral surface of the output sleeve (4) and the fixed sleeve (3) and the ball screw are both rolling bearings having rollers or balls interposed in a preloaded state. Therefore, backlash does not occur between one of the relative moving parts and the other. Therefore, the linear movement distance of the output sleeve (4) accurately corresponds to the rotation angle of the screw shaft (1). For example, when the rotation angle of the screw shaft (1) is accurately controlled by a servomotor or the like, the linear movement distance of the output sleeve (4) becomes an accurate value according to the rotation angle. Further, since the ball screw and the linear motion bearing both employ rolling bearings, the resistance between the relative moving parts is small. Therefore, the rotational movement force of the screw shaft (1) is efficiently converted to the linear movement force of the output sleeve (4).

* 3. In the item (2), the item “The ball screw is attached to the ball (1
0) Cylindrical ball retainer that holds each group so that it can rotate freely
In the configuration having (5), the ball (10) group moves while being held by the ball holder (5), so that a mechanism for returning the ball is not required, and the whole can be miniaturized.

* 4. In the above-mentioned item 1 to item 3, the “inner surface of the fixed sleeve (3) and the outer surface of the output sleeve (4) may be three or more substantially identical members provided at equal intervals in the circumferential direction. The roller retainer (6) is a cylindrical retainer that integrally retains a group of rollers (30) interposed between the opposing flat portions where the flat portions oppose each other. Is the roller
(30) are arranged on each side of the cross section of the output sleeve (4) formed in a regular polygon, so that each of the pre-pressed pressure from the roller (30) is applied to the center of the cross section of the output sleeve (4). Acts toward. Accordingly, the movement trajectory of the output sleeve (4) is maintained so as to coincide with the axis of the output sleeve (4) by the preload from the rollers (30) arranged along the plane portion. Therefore, when the output sleeve (4) moves, the output sleeve (4) does not run out, and the accuracy of the linear movement is high.

(5) In the item (3) or (4), the ball retainer (5) is a cylindrical body having a through-hole (51) group corresponding to the ball (10) group, At both ends in the direction, concave portions (52) that are open in the circumferential direction are formed on an extension of the arrangement direction of the through holes (51), and are located at both end positions of the movement area of the ball retainer (5) on the screw shaft (1). The pin (12) abutting on the concave portion (52) is formed so as to protrude from the screw groove (11). " In this device, the pin (12) provided on the screw shaft (1) comes into contact with the concave portion (52), preventing further movement of the ball retainer (5), and the reciprocating movement range of the output sleeve (4). Can be determined in advance in a predetermined range.

* 6. In the above items 3 to 5, "the ball retainer (5)
It is formed by cutting a blank (50) having a shape expanded and cut at the boundary between two groups of the through-holes (51) arranged in the axial direction into a cylindrical shape, and contacting the boundary at the boundary. Blank (50)
Both butting edges (55) are engaged with each other in a state of preventing relative movement '', in which the ball retainer (5) is formed by bending a punched plate into a cylindrical shape. The ball retainer (5) can be manufactured at low cost. Further, since both edges are meshed with each other, for example, when a metal plate is punched into the blank (50) having a predetermined shape and bent into a cylindrical shape, as long as the mating edges (55) mesh with each other. Thus, a precise cylindrical shape without displacement of the through-hole group (51) is obtained.

[0014]

According to the present invention having the above configuration, the following specific effects are obtained. Since the output sleeve (4) moves linearly while maintaining a fixed posture with respect to the fixed sleeve (3), the work attached to the output sleeve (4) does not need to keep the moving posture constant with other members. It is easy to use for a transfer device or an assembly device that moves a work in a fixed posture.

Since the output sleeve (4) is supported by a rolling bearing composed of a group of rollers (30) interposed in a preloaded state between the output sleeve (4) and the fixed sleeve (3), the output sleeve (4) is driven by the screw shaft (1). The output sleeve (4) can move at high speed,
There is no rattling in the direction of rotation. Therefore, the robot moves while maintaining the constant posture, and the linearity of the movement locus is high.

In the item (2), since there is no backlash in the relative moving portion of the ball screw, the linear moving distance of the work becomes an accurate value according to the rotation angle of the screw shaft (1). Also, the relative movement of both the linear motion bearing and ball screw is
Since the movement is based on the rolling movement, the operation of the output sleeve (4) can be accelerated, and the rotational movement force of the screw shaft (1) is efficiently converted to the linear movement force of the output sleeve (4).

According to the third aspect, in addition to the above effects, the ball screw does not require a mechanism for returning the ball, so that the overall size can be reduced.

According to the fourth aspect, in addition to the above effects, the output sleeve (4) does not oscillate during linear movement and has high linear movement accuracy.

In the item (5), when the ball retainer (5) is provided, the reciprocating range of the output sleeve (4) can be determined in advance to a predetermined range, and overrun of the output sleeve (4) can be prevented.

In the case of item 6, in addition to the above effects, the ball retainer (5) can be manufactured with high precision and at low cost.

[0021]

Next, embodiments of the present invention will be described in detail with reference to the drawings. The linear actuator according to this embodiment is driven by an output shaft (21) of a servomotor M for applying a rotational driving force, as shown in FIGS. For this reason, the output shaft (21) of the servomotor M
The fixed sleeve (3) is connected to a ring-shaped mounting base (31) connected to the end face from which the protrusion is made. The output sleeve (4) held by this fixed sleeve (3) to be able to move forward and backward.
The output shaft (21) is connected to a screw shaft (1) for driving the shaft forward and backward by a shaft coupling (22). The mounting base (31) is concentric with the output shaft (21), and the input side end (13) of the screw shaft (1) is formed in a cylindrical shape, and is formed with respect to the output shaft (21). And is in a transmission state via the tubular coupling (22).

In the shaft coupling (22), the inner peripheral surface and the outer peripheral surface are both serration surfaces. These serration surfaces are formed on the surface of the output shaft (21) and the input end. The torque transmission is performed by engaging the serration surface formed on the inner peripheral surface of the portion (13) so as to mesh with the serration surface, and sufficient torque transmission is possible even with a small size. Further, two bearings (32) are provided in the axial direction between the input side end (13) and the mounting base (31), and the end of the fixed sleeve (3) is connected to the bearing (32). And is connected and fixed to the mounting base (31) so as to fit over a part of the mounting base.

[Linear Bearing] In this example, the inner peripheral surface of the fixed sleeve (3) is formed in a regular hexagonal cross section as shown in FIG. 4, and the outer shape of the output sleeve (4) has a corner portion. It is a regular hexagonal section that has been removed. Therefore, the fixed sleeve
A substantially uniform interval is generated between (3) and the output sleeve (4), and the flat portion (32) of the fixed sleeve (3) and the flat portion (42) of the output sleeve (4) The six gaps are mutually constant.

In each of the six gaps between the flat portion (32) and the flat portion (42), a number of rollers (30) are in rolling contact with the flat portions so that they can roll in the axial direction. It is interposed at regular intervals. Then, a group of rectangular through-holes (61) accommodating these rollers (30) separately are divided into six flat portions (62).
A roller holder (6) having a substantially hexagonal cylindrical shape is formed between the fixed sleeve (3) and the output sleeve (4).
According to this roller holding notation (6), a large number of rollers (30) interposed between the respective flat portions allow the flat portions (3) to pass through the through holes (61).
Rolling is exposed in the side of (2) and (42) and comes into rolling contact, and linearly rolls in such a manner that the moving distance does not shift and the rolling posture is kept constant. The thickness of the roller retainer (6) is determined by the fixed sleeve (3) and the output sleeve.
The roller holder (6) is set to be smaller than the gap between the roller holder (4) and the roller holder (6) hardly becomes a sliding resistance during the relative movement.

[Ball Screw] The ball screw having the above configuration is provided between the inner peripheral surface of the output sleeve (4) and the screw shaft (1). On the inner peripheral surface of the output sleeve (4), a certain range is formed thick from the mounting table (31), and a thread groove (41) is formed in the thick part. On the other hand, a screw groove (11) is formed on the outer peripheral surface of the screw shaft (1) penetrating the output sleeve (4), and between these screw grooves (11) and (41),
A group of balls (10) is interposed at a constant pitch. These balls (10) are arranged in a pre-pressed state between the screw grooves at a predetermined pressure, that is, in a pre-pressed state.
There is no backlash in the even part of the screw between (1) and the output sleeve (4).

These balls (10) group are held by a thin-plate cylindrical ball holder (5) having through holes (51) formed in accordance with their arrangement pitch. The portion exposed inside and outside from the through hole (51) is in contact with the screw groove. A certain gap is formed between the threads of the screw grooves (11) and (41), and the thickness of the ball retainer (5) is set smaller than this gap. vessel
(5) is relatively movable with respect to the screw thread, and moves with the movement of the ball (10) group.

When the screw shaft (1) is rotated, the rotation is transmitted to the output sleeve (4) via the ball (10), and the output sleeve (4) can be moved linearly by the fixed sleeve (3). Since the rotation of the screw shaft is maintained, the output sleeve (4) linearly moves in the axial direction according to the rotation of the screw shaft. The ball retainer (5) also moves in the axial direction, but moves along a spiral path along the screw groove (11) with respect to the screw shaft.
In order to determine both end positions of the movement range on this trajectory, in this example, stopper pins (12) protruding at predetermined positions on the proximal and distal ends of the screw groove (11) of the screw shaft (1) are used. Provided.
Also, the edge (53) of the other ball retainer (5) is
The torsion line is formed along the line (1), and the ends of the torsion line are formed so as to be continuous with a step (54) parallel to the axial direction. The step (54) has a recess (52) that opens in the direction along the screw groove (11).

Ball retainer (5) by rotation of screw shaft (1)
When the shaft rotates and moves in the axial direction to reach both end positions, the concave portion (52) comes close to the pin (12), and finally they come into contact with each other. Therefore,
The combination of the pin (12) and the edge (53) having the concave portion (52) can prevent the screw shaft (1) of the ball screw from excessive rotation.

The ball retainer (5) can be made by bending a metal plate into a cylindrical shape. In this case, as shown in FIG. 6, a group of through-holes (51) corresponding to the screw grooves (11) and (41) is punched out, and four parallel sides surrounded by an edge (53) and a joining edge (55). A blank (50) having a shape is manufactured by punching, and then the cylindrical blank (50) is bent so that the butt edges (55) overlap. In this example, since the butting edges (55) are formed as wavy edges that mesh with each other, as long as these butting edges are correctly meshed, the through holes (51) are formed into a precise cylindrical shape without displacement. Become. Further, the position of the concave portion (52) formed on the edge (53) is also correct.

[Example of use and operation] The mounting base (31) of this linear motion actuator is mounted, for example, on the output end (100) of a transfer device capable of controlling the horizontal drive trajectory as shown in FIG. Then, by attaching the work W to the flange portion (43) as an operation output portion provided at the tip of the output sleeve (4) and controlling the transfer device and the servomotor M, the output sleeve (4) is leveled. This output sleeve (4) is moved in the direction
As described above, the work W is connected to the fixed sleeve (3) fixed to the mounting base (31), so that the work W is connected to the output shaft (21) of the servomotor M by the screw shaft.
It is driven up and down at a predetermined timing in accordance with the rotation of (1).

As described above, the work W can be accurately transferred along a predetermined trajectory under the control of the transfer device and the servomotor M. In the case of using the ball screw as described above, the movement resistance at the time of the elevating operation can be reduced and the movement can be accelerated. Further, since the ball (10) of the ball screw is preloaded and interposed between the screw grooves (11) and (41), there is no backlash, and the accuracy in controlling the moving distance can be increased.

In the above embodiment, the screw mechanism between the output sleeve (4) and the screw shaft (1) is a ball screw. Moreover,
Although a ball screw having a configuration in which the ball (10) group is rotatably held by the ball holder (5) is used, the ball screw may be a ball screw of a type in which the ball (10) group circulates through a return path. Further, a normal screw mechanism that does not use a ball may be used. The ball retainer of the ball screw of the above embodiment is a member formed by molding a blank (50) made of a metal plate into a cylindrical shape, but this may be an injection molded product made of a cylindrical synthetic resin.

The inner peripheral surface of the fixed sleeve (3) and the output sleeve
The outer peripheral surface of (4) does not have to be a regular polygon, but may be any sectional shape in which a plane portion is located on each side of the polygon. Further, the roller holder (6) may be separated for each area holding a group of rollers (30). The pin may be on the output sleeve output sleeve (4) side. The shaft coupling (22) may be a different type of shaft coupling from the type in which the serration surfaces mesh.

[Brief description of the drawings]

FIG. 1 is a sectional view of a linear actuator according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state in which an output sleeve (4) of FIG. 1 has advanced.

FIG. 3 is an enlarged sectional view of a linear actuator part;

FIG. 4 is a sectional view taken along line XX.

FIG. 5 is a sectional view taken along line YY.

FIG. 6 is a plan view of a blank (50).

FIG. 7 is an explanatory diagram of a usage example.

[Explanation of symbols]

(1): Screw shaft, (10): Ball, (11): Screw groove, (12): Pin, (13): Input end, (100): Output end, (2): Nut,
(21): Output shaft, (22): Shaft coupling (3): Fixed sleeve, (30): Roller, (31): Mounting base, (3
2): Flat part, (33): Bearing bearing, (4): Output sleeve, (41): Screw groove, (42): Flat part, (43) Flange part (5): Ball retainer, (50) : Blank, (51): Through-hole, (5
2): recess, (53): edge, (54): step, (55): butt edge (6): roller holder, (61): through hole, M: servo motor, W: work

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[Procedure amendment]

[Submission date] May 28, 2001 (2001.5.2)
8)

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Linear actuator

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion actuator, and more particularly, to a linear motion actuator in which an input shaft is rotationally driven by a drive unit and an output shaft interlocked with the input shaft is linearly driven.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 10-285867 has already been proposed as a linear motion actuator of this kind, which comprises a screw shaft connected to a rotation output shaft of a motor, and an external fitting fitted to the screw shaft. A movable table that linearly moves in a fixed posture, comprising a nut to be fixed, a cylindrical operating rod integrated with the nut, and a fixed sleeve holding the operating rod movably forward and backward via a ball bearing type linear motion bearing. Are connected to the distal end of the operating rod. Thus, the operating rod is linearly driven by the screw pair of the screw shaft and the nut according to the rotation of the motor.

At this time, the operating rod is rotatable with respect to the fixed sleeve. However, since the operating rod R is connected to a movable table whose movement posture is regulated so as to move linearly, the nut is screwed. The rotation of the screw shaft is converted into a linear movement of the operating rod without rotating together with the rotation of the shaft. Furthermore, since a ball bearing type linear bearing is interposed between the linear rod and the fixed sleeve, the movement resistance of this part is small and the rotational output of the motor is smoothly converted to linear movement of the linear rod. You.

However, in this conventional device, in order to prevent co-rotation between the linear motion rod and the screw shaft, the driven portion to be mounted on the linear motion rod is regulated so as to move linearly. This is indispensable, and there is a problem that this linear motion rod cannot be used as an operation output unit that reciprocates in a fixed posture as it is. In order to solve this problem, it is conceivable to hold the linear motion rod in a detent state by a fixed sleeve, but in this case, the sliding resistance in the holding part for the detent remains as another problem. .

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for driving an operation output section with respect to the fixed sleeve (3) by rotating a screw shaft (1) coaxial with the fixed sleeve (3). It is an object of the present invention to provide a linear motion actuator in which the operation output section itself is accurately linearly moved in a fixed posture, and also enables high-speed movement by reducing the friction of each of the relative movement sections.

[0006]

Means for Solving the Problems * 1 The technical means of the present invention for solving the above-mentioned problem is as follows: "The operation output portion is an output sleeve (3) accommodated in a movable manner with respect to the fixed sleeve (3). 4) and said fixed sleeve (3)
A flat portion extending in the longitudinal direction is formed at a plurality of locations and at positions opposed to each other in parallel with each other on the inner peripheral surface of the output sleeve (4) and the outer peripheral surface of the output sleeve (4). Between the fixed sleeve (3) and the output sleeve (4), a plurality of rollers (30) interposed in a pre-pressed state between the opposing flat portions, and these rollers. And a plurality of linear motion bearings comprising a roller retainer (6) for rotatably holding. "

The above technical means operates as follows. According to the above means, a plurality of linear motion bearings are interposed between the flat portions facing each other between the output sleeve (4) and the fixed sleeve (3) at positions corresponding to the respective sides of the polygonal cross section. Because
The output sleeve (4) and the fixed sleeve (3) relatively linearly move, but do not rotate (smooth-even relationship). Therefore, when the screw shaft (1) is driven to rotate, the output sleeve (4) is linearly moved in a constant posture in accordance with the direction of the rotation, and the work attached to the output sleeve (4) responds to the rotation. Is moved linearly. The rotation of the screw shaft (1) generates a rotational torque on the output sleeve (4),
This is supported by the roller (30) which is in a pre-pressed state between the flat portions facing the fixed sleeve (3),
The output sleeve (4) does not rattle in the rotational direction due to transmission from the screw shaft (1).

* 2. In the above item 1, "the screw groove formed on the inner peripheral surface of the output sleeve (4) is provided between the inner peripheral surface of the output sleeve (4) and the screw shaft (1). 41), a screw groove (11) formed on the outer peripheral surface of the screw shaft (1), and a ball screw including a plurality of balls (10) inserted in a preloaded state between the screw grooves. The output sleeve (4) is fixed with the rotation of the screw shaft (1) by the action of the ball screw.
It moves linearly with respect to (3). The relative movement between the output sleeve (4) and the screw shaft (1) is accompanied by the rolling of the ball (10) held between the screw grooves (41) and (11).

Accordingly, the linear motion bearing between the outer peripheral surface of the output sleeve (4) and the fixed sleeve (3) and the ball screw are both rolling bearings having rollers or balls interposed in a preloaded state. Therefore, backlash does not occur between one of the relative moving parts and the other. Therefore, the linear movement distance of the output sleeve (4) accurately corresponds to the rotation angle of the screw shaft (1). For example, when the rotation angle of the screw shaft (1) is accurately controlled by a servomotor or the like, the linear movement distance of the output sleeve (4) becomes an accurate value according to the rotation angle. Further, since the ball screw and the linear motion bearing both employ rolling bearings, the resistance between the relative moving parts is small. Therefore, the rotational movement force of the screw shaft (1) is efficiently converted to the linear movement force of the output sleeve (4).

* 3. In the item (2), the item “The ball screw is attached to the ball (1
0) Cylindrical ball retainer that holds each group so that it can rotate freely
In the configuration having (5), the ball (10) group moves while being held by the ball holder (5), so that a mechanism for returning the ball is not required, and the whole can be miniaturized.

* 4. In the above-mentioned item 1 to item 3, the “inner surface of the fixed sleeve (3) and the outer surface of the output sleeve (4) may be three or more substantially identical members provided at equal intervals in the circumferential direction. The roller retainer (6) is a cylindrical retainer that integrally retains a group of rollers (30) interposed between the opposing flat portions where the flat portions oppose each other. Is the roller
(30) are arranged on each side of the cross section of the output sleeve (4) formed in a regular polygon, so that each of the pre-pressed pressure from the roller (30) is applied to the center of the cross section of the output sleeve (4). Acts toward. Accordingly, the movement trajectory of the output sleeve (4) is maintained so as to coincide with the axis of the output sleeve (4) by the preload from the rollers (30) arranged along the plane portion. Therefore, when the output sleeve (4) moves, the output sleeve (4) does not run out, and the accuracy of the linear movement is high.

(5) In the item (3) or (4), the ball retainer (5) is a cylindrical body having a through-hole (51) group corresponding to the ball (10) group, At both ends in the direction, concave portions (52) that are open in the circumferential direction are formed on an extension of the arrangement direction of the through holes (51), and are located at both end positions of the movement area of the ball retainer (5) on the screw shaft (1). The pin (12) abutting on the concave portion (52) is formed so as to protrude from the screw groove (11). " In this device, the pin (12) provided on the screw shaft (1) comes into contact with the concave portion (52), preventing further movement of the ball retainer (5), and the reciprocating movement range of the output sleeve (4). Can be determined in advance in a predetermined range.

* 6. In the above items 3 to 5, "the ball retainer (5)
It is formed by cutting a blank (50) having a shape expanded and cut at the boundary between two groups of the through-holes (51) arranged in the axial direction into a cylindrical shape, and contacting the boundary at the boundary. Blank (50)
Both butted edges (55) are engaged with each other in a state of preventing relative movement. ' The ball retainer (5) can be manufactured at low cost. Further, since both edges are meshed with each other, for example, when a metal plate is punched into the blank (50) having a predetermined shape and bent into a cylindrical shape, as long as the mating edges (55) mesh with each other. Thus, a precise cylindrical shape without displacement of the through-hole group (51) is obtained.

[0014]

According to the present invention having the above configuration, the following specific effects are obtained. Since the output sleeve (4) moves linearly while maintaining a fixed posture with respect to the fixed sleeve (3), the work attached to the output sleeve (4) does not need to keep the moving posture constant with other members. It is easy to use for a transfer device or an assembly device that moves a work in a fixed posture.

Since the output sleeve (4) is supported by a rolling bearing composed of a group of rollers (30) interposed in a preloaded state between the output sleeve (4) and the fixed sleeve (3), the output sleeve (4) is driven by the screw shaft (1). The output sleeve (4) can move at high speed,
There is no rattling in the direction of rotation. Therefore, the robot moves while maintaining the constant posture, and the linearity of the movement locus is high.

In the item (2), since there is no backlash in the relative moving portion of the ball screw, the linear moving distance of the work becomes an accurate value according to the rotation angle of the screw shaft (1). Also, the relative movement of both the linear motion bearing and ball screw is
Since the movement is based on the rolling movement, the operation of the output sleeve (4) can be accelerated, and the rotational movement force of the screw shaft (1) is efficiently converted to the linear movement force of the output sleeve (4).

According to the third aspect, in addition to the above effects, the ball screw does not require a mechanism for returning the ball, so that the overall size can be reduced.

According to the fourth aspect, in addition to the above effects, the output sleeve (4) does not oscillate during linear movement and has high linear movement accuracy.

In the item (5), when the ball retainer (5) is provided, the reciprocating range of the output sleeve (4) can be determined in advance to a predetermined range, and overrun of the output sleeve (4) can be prevented.

In the case of item 6, in addition to the above effects, the ball retainer (5) can be manufactured with high precision and at low cost.

[0021]

Next, embodiments of the present invention will be described in detail with reference to the drawings. The linear motion actuator of this embodiment is driven by an output shaft (21) of a servomotor M for applying a rotational driving force, as shown in FIGS. For this reason, the output shaft (2
A ring-shaped mounting base (31) that is connected to the end face that protrudes 1)
The stationary sleeve (3) is connected to the stationary sleeve. Output sleeve held forward and backward by this fixed sleeve (3)
(4) to the screw shaft (1) for driving forward and backward, the output shaft (21)
Are connected by a shaft coupling (22). The mounting base (31)
Is concentric with the output shaft (21), the input end (13) of the screw shaft (1) is formed in a cylindrical shape, and the shaft is cylindrical with respect to the output shaft (21). It is in a transmission state via the joint (22).

In the shaft coupling (22), the inner peripheral surface and the outer peripheral surface are both serration surfaces. These serration surfaces are formed on the surface of the output shaft (21) and the input end. The torque transmission is performed by engaging the serration surface formed on the inner peripheral surface of the portion (13) so as to mesh with the serration surface, and sufficient torque transmission is possible even with a small size. Further, two bearings (32) are provided in the axial direction between the input side end (13) and the mounting base (31), and the end of the fixed sleeve (3) is connected to the bearing (32). And is fixedly connected to the mounting base (31) so as to be fitted to a part of the mounting base.

[Linear Bearing] In this example, the inner peripheral surface of the fixed sleeve (3) is formed in a regular hexagonal cross section as shown in FIG. 4, and the outer shape of the output sleeve (4) has a corner portion. It is a regular hexagonal section that has been removed. Therefore, the fixed sleeve
A substantially uniform interval is generated between (3) and the output sleeve (4), and the flat portion (32) of the fixed sleeve (3) and the flat portion (42) of the output sleeve (4) The six gaps are mutually constant.

In each of the six gaps between the flat portion (32) and the flat portion (42), a number of rollers (30) are in rolling contact with the flat portions so that they can roll in the axial direction. It is interposed at regular intervals. Then, a group of rectangular through-holes (61) accommodating these rollers (30) separately are divided into six flat portions (62).
A roller holder (6) having a substantially hexagonal cylindrical shape is formed between the fixed sleeve (3) and the output sleeve (4).
According to this roller holding notation (6), a large number of rollers (30) interposed between the respective flat portions allow the flat portions (3) to pass through the through holes (61).
Rolling is exposed in the side of (2) and (42) and comes into rolling contact, and linearly rolls in such a manner that the moving distance does not shift and the rolling posture is kept constant. The thickness of the roller retainer (6) is determined by the fixed sleeve (3) and the output sleeve.
The roller holder (6) is set to be smaller than the gap between the roller holder (4) and the roller holder (6) hardly becomes a sliding resistance during the relative movement.

[Ball Screw] The ball screw having the above configuration is provided between the inner peripheral surface of the output sleeve (4) and the screw shaft (1). On the inner peripheral surface of the output sleeve (4), a certain range is formed thick from the mounting table (31), and a thread groove (41) is formed in the thick part. On the other hand, a screw groove (11) is formed on the outer peripheral surface of the screw shaft (1) penetrating the output sleeve (4), and between these screw grooves (11) and (41),
A group of balls (10) is interposed at a constant pitch. These balls (10) are arranged in a pre-pressed state between the screw grooves at a predetermined pressure, that is, in a pre-pressed state.
There is no backlash in the even part of the screw between (1) and the output sleeve (4).

These balls (10) group are held by a thin-plate cylindrical ball holder (5) having through holes (51) formed in accordance with their arrangement pitch. The portion exposed inside and outside from the through hole (51) is in contact with the screw groove. A certain gap is formed between the threads of the screw grooves (11) and (41), and the thickness of the ball retainer (5) is set smaller than this gap. vessel
(5) is relatively movable with respect to the screw thread, and moves with the movement of the ball (10) group.

When the screw shaft (1) is rotated, the rotation is transmitted to the output sleeve (4) via the ball (10), and the output sleeve (4) can be moved linearly by the fixed sleeve (3). Since the rotation of the screw shaft is maintained, the output sleeve (4) linearly moves in the axial direction according to the rotation of the screw shaft. The ball retainer (5) also moves in the axial direction, but moves along a spiral path along the screw groove (11) with respect to the screw shaft.
In order to determine both end positions of the movement range on this trajectory, in this example, stopper pins (12) protruding at predetermined positions on the proximal and distal ends of the screw groove (11) of the screw shaft (1) are used. Provided.
Also, the edge (53) of the other ball retainer (5) is
The torsion line is formed along the line (1), and the ends of the torsion line are formed so as to be continuous with a step (54) parallel to the axial direction. The step (54) has a recess (52) that opens in the direction along the screw groove (11).

Ball retainer (5) by rotation of screw shaft (1)
When the shaft rotates and moves in the axial direction to reach both end positions, the concave portion (52) comes close to the pin (12), and finally they come into contact with each other. Therefore,
The combination of the pin (12) and the edge (53) having the concave portion (52) can prevent the screw shaft (1) of the ball screw from excessive rotation.

The ball retainer (5) can be made by bending a metal plate into a cylindrical shape. In this case, as shown in FIG. 6, a group of through-holes (51) corresponding to the screw grooves (11) and (41) is punched out, and four parallel sides surrounded by an edge (53) and a joining edge (55). A blank (50) having a shape is manufactured by punching, and then the cylindrical blank (50) is bent so that the butt edges (55) overlap. In this example, the butting edges (55) are formed as wavy edges that mesh with each other. Become. Further, the position of the concave portion (52) formed on the edge (53) is also correct.

[Usage Example and Operation] The mounting base (31) of this linear motion actuator is mounted on an output end (100) of a transfer device capable of controlling a horizontal drive trajectory, for example, as shown in FIG. Then, by attaching the work W to the flange portion (43) as an operation output portion provided at the tip of the output sleeve (4) and controlling the transfer device and the servomotor M, the output sleeve (4) is leveled. This output sleeve (4) is moved in the direction
As described above, the work W is connected to the fixed sleeve (3) fixed to the mounting base (31), so that the work W is connected to the output shaft (21) of the servomotor M by the screw shaft.
It is driven up and down at a predetermined timing in accordance with the rotation of (1).

As described above, the work W can be accurately transferred along a predetermined trajectory under the control of the transfer device and the servomotor M. In the case of using the ball screw as described above, the movement resistance at the time of the elevating operation can be reduced and the movement can be accelerated. Further, since the ball (10) of the ball screw is preloaded and interposed between the screw grooves (11) and (41), there is no backlash, and the accuracy in controlling the moving distance can be increased.

In the above embodiment, the screw mechanism between the output sleeve (4) and the screw shaft (1) is a ball screw. Moreover,
Although a ball screw having a configuration in which the ball (10) group is rotatably held by the ball holder (5) is used, the ball screw may be a ball screw of a type in which the ball (10) group circulates through a return path. Further, a normal screw mechanism that does not use a ball may be used. The ball retainer of the ball screw of the above embodiment is a member formed by molding a blank (50) made of a metal plate into a cylindrical shape, but this may be an injection molded product made of a cylindrical synthetic resin.

The inner peripheral surface of the fixed sleeve (3) and the output sleeve
The outer peripheral surface of (4) does not have to be a regular polygon, but may be any sectional shape in which a plane portion is located on each side of the polygon. Further, the roller holder (6) may be separated for each area holding a group of rollers (30). The pin may be on the output sleeve output sleeve (4) side. The shaft coupling (22) may be a different type of shaft coupling from the type in which the serration surfaces mesh.

[Brief description of the drawings]

FIG. 1 is a sectional view of a linear motion actuator according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state in which an output sleeve (4) of FIG. 1 has advanced.

FIG. 3 is an enlarged sectional view of a linear motion actuator portion.

FIG. 4 is a sectional view taken along line XX.

FIG. 5 is a sectional view taken along line YY.

FIG. 6 is a plan view of a blank (50).

FIG. 7 is an explanatory diagram of a usage example.

[Description of Signs] (1): Screw shaft, (10): Ball, (11): Screw groove, (12): Pin, (13): Input end, (100): Output end, (2) :nut,
(21): Output shaft, (22): Shaft coupling (3): Fixed sleeve, (30): Roller, (31): Mounting base, (3
2): Flat part, (33): Bearing bearing, (4): Output sleeve, (41): Screw groove, (42): Flat part, (43) Flange part (5): Ball retainer, (50) : Blank, (51): Through-hole, (5
2): recess, (53): edge, (54): step, (55): butt edge (6): roller holder, (61): through hole, M: servo motor, W: work

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 7/06 H02K 7/06 A F term (Reference) 3J101 AA13 AA24 AA32 AA44 AA52 AA64 AA72 AA85 BA34 BA44 FA60 GA60 3J104 AA13 AA19 AA25 AA37 AA67 AA69 AA75 AA76 AA79 BA41 DA06 DA13 EA10 5H607 AA12 BB01 CC03 DD19 EE52 GG07 GG08

Claims (6)

[Claims] An operation output section is driven by rotating a screw shaft (1) which is coaxial with a fixed sleeve (3).
In the linear motion actuator driven forward and backward with respect to (3), the operation output section is an output sleeve (4) housed so as to be able to move forward and backward with respect to the fixed sleeve (3). On the peripheral surface and the outer peripheral surface of the output sleeve (4), flat portions extending in the longitudinal direction are formed at a plurality of locations and at positions facing each other in parallel, and the plurality of locations are located at positions corresponding to respective sides of the polygon. The fixing sleeve
Between the (3) and the output sleeve (4), a plurality of rollers (30) interposed in a pre-pressed state between the opposed flat portions, and a roller holder (6) for holding these rollers rotatably. A linear motion actuator having a plurality of linear motion bearings. 2. The linear motion actuator according to claim 1, wherein an inner peripheral surface of the output sleeve is formed between the inner peripheral surface of the output sleeve and the screw shaft. Screw groove (41) and the screw groove (11) formed on the outer peripheral surface of the screw shaft (1)
And a ball screw having a plurality of balls (10) inserted between these screw grooves in a preloaded state. 3. A linear motion actuator according to claim 2, wherein said ball screw comprises a cylindrical ball retainer (5) for individually holding said balls (10) in a freely rotatable manner. , Linear actuator. 4. The linear actuator according to claim 1, wherein the inner surface of the fixed sleeve and the outer surface of the output sleeve are provided at equal intervals in a circumferential direction.
The above-described plurality of substantially identical flat portions face each other, and the roller retainer (6) is a cylindrical retainer that integrally holds a group of rollers (30) interposed between the opposed flat portions. Is,
Linear actuator. 5. The linear actuator according to claim 3, wherein the ball retainer (5) is a cylindrical body having a group of through-holes (51) corresponding to the group of the balls (10), and is arranged in the axial direction. A concave portion (52) that opens in the circumferential direction is provided at both ends of the through hole (5).
The concave portion is formed on an extension line in the arrangement direction of 1), and is located at both ends of the movement area of the ball retainer (5) on the screw shaft (1).
A linear actuator in which a pin (12) abutting on (52) is formed to project from the screw groove (11). 6. The linear actuator according to claim 3, wherein the ball retainers (5) are arranged in the axial direction.
It is formed by bending a blank (50) having a shape expanded and cut at the boundary of the group of through holes (51) in a row into a cylindrical shape,
A linear actuator in which both butting edges (55) of the blank (50) abutting at the boundary are engaged with each other in a state of preventing relative movement.