KR100918619B1 - Roller screw type linear actuator - Google Patents

Abstract

PURPOSE: A roller screw type linear actuator is provided to simplify a power transmission structure by arranging an output axis inside a plurality of rotation screws. CONSTITUTION: A rotary motion unit includes a rotation screw(141). A thread is formed in an outer circumference along the length direction of the body of the rotation screw. A plurality of rotation screws are arranged around an output axis(151). The rotation screw generates thrust with regard to the output axis by rotating when a motor is driven. A motor power transmission member(130) is combined in the end of the axis of the motor. The motor power transmission member is installed in the center of the plurality of rotation screws. The motor power transmission member transmits the power of the motor to the plurality of rotation screws. The output axis of a linear motion unit is geared with the threads of the plurality of rotation screws and linearly reciprocates when the plurality of rotation screws rotate.

Description

Roller Actuator Linear Actuator {ROLLER SCREW TYPE LINEAR ACTUATOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator for use in various industrial machinery, and more particularly, to a roller screw type linear actuator having a simple driving structure and no need for using a hollow shaft, thereby reducing processing costs.

In general, factory automation transfer, transfer supply and assembly, conveying line, industrial Cartesian robot, conveying machine and lift device, automatic door and conveying device of CNC machine tool, industrial automatic door field, packing, welding, painting machine Linear actuators for linearly moving objects are used in various industrial machines such as linear motion devices.

Such linear actuators are known rack and pinion, hydraulic / pneumatic cylinders, lead screws, ball screws and roller screw types.

The lead screw type linear actuator is composed of a drive shaft that is rotated by the drive of a motor and a driven body (output shaft) meshed with the drive shaft and linearly reciprocated. This type of linear actuator has a large sliding friction area between the drive shaft and the driven body, which makes it difficult to move at high speeds and has a short life due to malfunctions caused by damage to the sliding parts. There is a disadvantage in that the working load cannot be increased.

The ball screw type linear actuator is composed of a drive shaft that is rotated by the drive of a motor and a driven member that is linearly reciprocated by threaded engagement with the drive shaft, and a ball bearing is inserted between the drive shaft and the driven body to provide frictional resistance. It is intended to reduce. Such a ball screw type linear actuator is used where the point contact is made between the ball bearing and the driven body so that the frictional resistance is low and the precise position control is made, but it is difficult to use when the load applied from the driven body is large.

On the other hand, in the roller screw type linear actuator, a roller is used instead of a ball bearing in the ball screw type linear actuator. 1 is a view showing a cross-sectional structure of a roller screw type linear actuator disclosed in Japanese Patent Laid-Open No. Hei 10-196756. Referring to FIG. 1, a roller screw shaft 12 which is decelerated and rotated by a drive of a motor and has a screw formed on an outer circumferential surface, a front and rear set of roller nuts 14 having a female thread formed on an inner circumferential surface, and a fraud roller screw shaft ( 12) and a plurality of planetary rollers 16 engaged with screws and female threads between the roller nut 14 and the planetary roller 16 and the roller nut 14 in accordance with the rotation of the roller screw shaft 12. The output shaft 32 which linearly moves is provided.

According to this structure, the number of contacts between the roller screw shaft 12 and the planetary roller 16 is large, so that it can withstand a large load acting on the planetary roller 16 from the output shaft 32 and has an advantage of precise position control. In small servo presses, linear actuators of roller screw type are required instead of ball screw type.

However, since the roller screw shaft 12 corresponding to the driving shaft is installed inside the driven shaft output shaft 32, the output shaft 32 should be processed into a hollow hollow shaft, which is expensive to process. There is a problem. In addition, many components such as a roller screw shaft 12, a plurality of planetary rollers 16, a roller nut 14, and an adapter 22 are required in order to convert the rotational movement into a linear movement. The roller screw shaft 12 And the planetary roller 16 and the roller nut 14 has a problem that the processing cost is high because the thread processing on the outer peripheral surface and the inner peripheral surface respectively. In the case of the patented roller nut 14, there is a problem in that the machining cost increases and the machining accuracy decreases because the machining is performed on the inner circumferential surface.

In addition, since the linear actuator of the above structure has only one driving shaft for transmitting the power of the motor to the output shaft (in the case of FIG. 1, the roller screw shaft 12 corresponds to this), the precision of the linear motion due to the machining error of the driving shaft is increased. There is a problem that can be degraded.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a linear actuator of a roller screw type with a high power efficiency and a small processing cost and high efficiency. Another object of the present invention is to provide a roller screw linear actuator capable of improving the accuracy of linear motion.

The linear actuator of the present invention for achieving the above object, by converting the rotational driving force of the rotary motion portion 140 rotated by the drive source 110 into a linear motion to reciprocate the output shaft 151 of the linear motion portion 150 In the linear actuator, the rotary motion portion 140, the thread formed on the outer peripheral surface along the longitudinal direction of the body includes a plurality of rotating screws (141) disposed around the output shaft (151) around; The output shaft 151 of the linear movement unit 150 is engaged with the plurality of rotary screws 141 by a screw thread to linearly reciprocate during rotation of the plurality of rotary screws 141.

According to the present invention, the rotating screw and the output shaft can withstand a large load because the rotational motion is converted into linear motion in a state where the threads of the outer circumferential surface are in line contact. In addition, the output shaft is arranged inside a plurality of rotating screws to simplify the power transmission structure, thereby reducing the processing elements, and the processing cost is reduced because the output shaft combined with the object to be linearly moved does not need to be machined into the hollow shaft. There is. In addition, there is an effect of improving the linear motion accuracy by averaging and correcting the individual screw error by rotating the number of the rotating screw to transmit power to the output shaft.

1 is a view showing a cross-sectional structure of a roller screw type linear actuator disclosed in Japanese Patent Laid-Open No. 10-196756;

Figure 2 is a perspective view showing a linear actuator according to an embodiment of the present invention,

Figure 3 is an exploded perspective view of the linear actuator shown in Figure 2, Figure 4 is a cross-sectional view A-A of FIG.

4 is a cross-sectional view taken along line A-A of FIG.

5 is a cross-sectional view taken along line B-B of FIG. 4;

6 is a cross-sectional view taken along line C-C of FIG.

Figure 7 is a schematic cross-sectional view showing a structure in which the support is installed on the outside of the rotating screw as another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

110: drive source 120: first support block

130: motor power transmission member 140: rotary motion portion

141: rotating screw 142: rotating screw power transmission member

150: linear motion unit 151: output shaft

152: output shaft power transmission member 153: bearing

160: second support block 170: cover member

181,182,183 fastening member 190 support member

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a perspective view showing a linear actuator according to an embodiment of the present invention, Figure 3 is an exploded perspective view of the linear actuator shown in Figure 2, Figure 4 is a cross-sectional view A-A of FIG.

The present invention, the drive source 110 for generating a rotational driving force, the first support block 120 for supporting one end of the rotating screw 141, the power transmission member 130 for transmitting the rotational driving force of the drive source (110). ), The rotary movement unit 140 is connected to the power transmission member 130 to include a rotary screw 141 to rotate, the linear movement unit 150 is converted into a linear reciprocating motion of the rotary movement unit 140 The cover member 170 includes a second support block 160 for supporting the other end of the rotating screw 141 and the rotational motion 140 and the linear motion 150.

The drive source 110 is made of, for example, a motor. The rotational force of the motor is transmitted to the motor power transmission member 130 through the shaft 111. A key protrudes from the shaft 111, and a key groove is formed in the motor power transmission member 130, and a key portion of the shaft 111 is formed in the key groove of the motor power transmission member 130. It is inserted and rotates integrally.

The driving source 110 is coupled to the first support block 120 by the fastening member 181.

The motor power transmission member 130 is connected to the rotary motion 140. The rotary motion unit 140 is coupled to one end of the plurality of rotary screws 141, the rotating screw 141, the screw thread is formed on the outer peripheral surface of the rotating screw power meshed with the motor power transmission member 130 Transfer member 142, bearings (143,144) coupled to both ends of the rotating screw 141, respectively.

In this embodiment, the number of the rotating screw 141 is composed of four. However, the present invention is not limited thereto, and may be configured as three or less or five or more in consideration of the volume and load of the device.

The motor power transmission member 130 and the rotating screw power transmission member 142 are in the form of a gear having an outer circumferential surface in contact with each other to transmit rotational force in an engaged state. In this case, the motor power transmission member 130 is positioned at the center, and four rotation screw power transmission members 142 are disposed at intervals of 90 ° along the circumference of the outer circumferential surface of the motor power transmission member 130. Therefore, when the motor power transmission member 130 rotates, the four rotating screw power transmission member 142 and the rotating screw 141 coupled thereto are also rotated together.

The bearing 143 of one side is inserted into a bearing insertion groove (not shown) formed in one side of the first support block 120 in a state of being fitted at one end of the rotating screw 141 to rotate the rotating screw 141. Support to be rotatable. In addition, the bearing 144 on the other side is inserted into the groove 161 formed on one side of the second support block 160 in a state of being fitted at the other end of the rotating screw 141 to rotatably support the rotating screw 141. . Therefore, the rotating screw 141 is to rotate in place (rotation) in a fixed position. As a result, thrust is generated with respect to the output shaft 141.

In the middle of the four rotating screws 141, a linear movement part 150 for linear reciprocating motion is installed.

The linear movement unit 150 is coupled to one end of the output shaft 151, the output shaft 151, the linear shaft reciprocating motion is coupled to the object to be linearly engaged with the four rotating screw 141 by a screw thread The output shaft power transmission member 152, and the bearing 153 is inserted into the output shaft power transmission member 152.

The output shaft power transmission member 152 is rotated when the rotating screw 141 rotates while the threads formed on the four rotating screws 141 body and the threads formed on the outer circumferential surface of the output shaft power transmission member 152 are engaged with each other. It is linearly integrated with the output shaft 151.

A bearing 153 is inserted into the output shaft power transmission member 152 to rotate freely about the output shaft 151. The bearing 153 is preferably composed of a thrust bearing capable of receiving an axial load.

In this case, due to the structure in which the four rotating screws 141 are disposed around the outer periphery of the output shaft 151, the output shaft 151 does not need to be processed into a hollow shaft as in the prior art, thereby reducing the processing cost.

In addition, four rotation screws 141 are configured to transmit power to the output shaft power transmission member 152, thereby improving the accuracy of the linear motion. In other words, when there is only one rotating screw, when the precision of machining of one of the rotating screws falls, it affects the precision of the linear motion as it is. On the contrary, in the present invention, since the four rotating screws 141 average and correct the accuracy error, the accuracy of the linear motion is improved as compared with the case of only one rotating screw.

In addition, since the frictional load acting between the rotating screw 141 and the output shaft power transmission member 152 is reduced, the energy efficiency is increased.

The output shaft 151 is installed to pass through the output shaft through hole 162 of the second support block 160.

A bearing insertion groove 161 is formed in the second support block 160 to insert the bearing 144 coupled to the end of the rotating screw 141.

Accordingly, the rotating screw 141 has bearings 143 and 144 coupled to both ends of the bearing insertion grooves (not shown) of the first support block 120 and the bearing insertion grooves 161 of the second support block 160. Are respectively rotatably supported.

The rotary motion part 140 and the linear motion part 150 are installed inside the cover member 170. The cover member 170 includes an upper first cover 171, a second cover 172 on the left and right sides, a third cover 173, and a lower fourth cover 174.

Front ends of the first to fourth covers 171, 172, 173, and 174 are fixedly coupled to the first support block 120 by the fastening member 182.

In addition, the rear ends of the first to fourth covers 171, 172, 173, and 174 are fixedly coupled by the second support block 160 and the fastening member 183.

5 is a cross-sectional view taken along line B-B in FIG. 4.

Referring to FIG. 5, the motor power transmission member 130 is disposed in the middle, and four rotating screw power transmission members 142 are installed in a square shape at intervals of 90 °.

The gear teeth are formed on the outer circumferential surfaces of the motor power transmission member 130 and the rotating screw power transmission member 142 to show a state of meshing with each other. In this state, when the motor power transmission member 130 rotates, the rotation screw power transmission member 142 and the rotation screw 141 integrally coupled thereto are also rotated together.

6 is a cross-sectional view taken along the line C-C of FIG.

Referring to FIG. 6, the output shaft power transmission member 152 is disposed in the middle, and four rotation screws 141 are installed in a square shape at intervals of 90 ° around the output shaft power transmission member 152.

The outer circumferential surface of the output shaft power transmission member 152 and the rotating screw 141 is formed with a screw thread is shown to mesh with each other. In this case, when the thread is engaged with the thread, it is able to withstand a large load because of the line contact.

When the rotating screw 141 rotates in this state, the output shaft power transmission member 152 and the output shaft 151 integrally coupled thereto are linearly moved.

Figure 7 is a schematic cross-sectional view showing a structure in which the support is installed on the outside of the rotating screw as another embodiment of the present invention.

When the load of an object moving linearly coupled to the output shaft 151 is heavy, the load acting on the rotating screw 141 may be large, and thus the four rotating screws 141 may be opened to the outside.

In order to prevent this, it is preferable that the support member 190 is installed to prevent the plurality of rotating screws 141 from spreading outward.

The support member 190 has an annular shape, and a thread is formed on the inner circumferential surface thereof, and the inner circumferential surface on which the thread is formed is engaged with the outer circumferential surfaces of the four rotating screws 141 having the thread formed on the outer circumferential surface thereof. Accordingly, when the rotating screw 141 is rotated, the support member 190 is linearly reciprocated.

When the support member 190 is installed as described above, it is obvious to those skilled in the art that the shape of the cover member 170 should be changed to correspond thereto.

Claims (7)

In the roller screw type linear actuator which reciprocates the output shaft 151 of the linear motion part 150 by converting the rotational driving force of the rotary motion part 140 rotated by the drive source 110 including the motor into linear motion, The rotational movement part 140 is formed with a screw thread on the outer circumferential surface along the longitudinal direction of the body, and a plurality of the rotational movement parts are disposed around the output shaft 151 to rotate when the motor is driven. Rotating screw 141 for generating a thrust relative to); The motor power transmission member 130 is coupled to the shaft end of the motor so as to be installed at the center of the plurality of rotating screws 141 so that the power of the motor is transmitted to the plurality of rotating screws 141; The output shaft 151 of the linear movement unit 150 is engaged with the plurality of rotary screws 141 by a screw thread to linearly reciprocate during rotation of the plurality of rotary screws 141; Roller actuator type linear actuator, characterized in that. The method of claim 1, The rotary motion unit 140, the gear teeth are formed on the outer circumferential surface includes a rotary screw power transmission member 142 coupled to the motor side end of the rotary screw 141; Roller actuator type linear actuator, characterized in that arranged around the motor power transmission member 130, the plurality of rotating screw power transmission member 142 is engaged. The method according to claim 1 or 2, The linear movement unit 150, the outer peripheral surface is engaged with the screw screw 141 and the roller screw system, characterized in that it comprises an output shaft power transmission member 152 freely rotated by the bearing 153 is inserted therein. Linear actuator. The method of claim 3, The bearing (153) is a roller screw linear actuator, characterized in that the thrust bearing which can be subjected to the axial load. The method according to claim 1 or 2, The rotary screw 141 is a roller screw type linear actuator, characterized in that four are arranged around the output shaft 151 at intervals of 90 degrees. The method according to claim 1 or 2, Roller screw type linear actuator, characterized in that the support member 190 is installed to prevent the plurality of rotating screws 141 to spread outward. The method of claim 6, The support member 190 is an annular, the screw thread is formed on the inner circumferential surface, the inner circumferential surface of the support member 190 is a roller screw type linear actuator, characterized in that the threaded engagement with the outer circumferential surface of the plurality of rotating screws 141. .