JP2021110344A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator configured to be able to move a rod in an axial direction and rotate in a circumferential direction, which is easy to assemble. An actuator 100 has a cylinder 102, a piston 104 slidably housed in the cylinder 102, a rod 106 extending from the piston 104 and projecting to the outside of the cylinder 102, and the rod coaxially with the rod 106. A rotational drive source for rotationally driving and a support portion 108 for rotatably supporting the rod 106 are provided. The support portion 108 is configured to allow the central axis of the rod 106 to deviate from the central axis of the support portion 108. [Selection diagram] Fig. 1

Description

The present invention relates to an actuator.

Patent Document 1 discloses a fluid pressure actuator that slides a rod in the axial direction using a fluid as an operating medium. This fluid pressure actuator is configured to rotate the rod in the circumferential direction by a driving force transmitted from the rotational drive via the belt.

Japanese Unexamined Patent Publication No. 2017-133593

An actuator as disclosed in Patent Document 1 is generally difficult to assemble, and even if it is assembled, the piston may bite (contact) the cylinder.

The present invention has been made in view of such a situation, and one of the exemplary purposes of the embodiment is an actuator configured to move the rod in the axial direction and rotate in the circumferential direction. The purpose is to provide an actuator that is easy to assemble.

In order to solve the above problems, the actuator of an embodiment of the present invention rotationally drives a cylinder, a piston slidably housed in the cylinder, a rod extending from the piston and projecting to the outside of the cylinder, and a rod. , A rotary drive source having a rotary shaft coaxial with the rod, and a support portion for rotatably supporting the rod. The support portion is configured to allow the central axis of the rod to deviate from the central axis of the support portion.

It should be noted that any combination of the above components and those in which the components and expressions of the present invention are mutually replaced between methods, devices, systems and the like are also effective as aspects of the present invention.

According to the present invention, it is possible to provide an actuator configured to be able to move the rod in the axial direction and rotate in the circumferential direction, which is easy to assemble.

It is a figure which shows typically the actuator which concerns on 1st Embodiment. It is a figure which shows typically the actuator which concerns on 2nd Embodiment.

Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and redundant description will be omitted as appropriate. Further, the embodiment is not limited to the invention but is an example, and all the features and combinations thereof described in the embodiment are not necessarily essential to the invention.

(First Embodiment)
FIG. 1 is a diagram schematically showing an actuator 100 according to the first embodiment. The actuator 100 is a fluid pressure actuator that uses a fluid as an operating medium. In the following, a case where air is used as an operating medium will be illustrated.

The actuator 100 includes a cylinder 102, a piston 104, a rod 106, a support portion 108, a pressure adjusting portion 110, a rotation drive source 112, and a controller 114.

Hereinafter, the direction parallel to the central axis of the cylinder 102 is referred to as an axial direction, and the direction along the circumference of the circle perpendicular to the central axis centered on the central axis of the cylinder 102 will be described as the circumferential direction.

The cylinder 102 includes a cylinder portion 116, a bottom portion 118, and a cover portion 120. The hollow portion 116a of the tubular portion 116 has a circular cross section. The central axis of the cylinder 102 described above specifically refers to the central axis of the hollow portion 116a of the cylinder portion 116. The outer shape of the tubular portion 116 is not particularly limited, but has, for example, a quadrangular cross section. The bottom portion 118 closes one end of the tubular portion 116 (the left end in FIG. 1), and the cover portion 120 closes the other end of the tubular portion 116 (the right end in FIG. 1). The bottom portion 118 and the cover portion 120 may be formed integrally with the tubular portion 116, or may be formed separately from the tubular portion 116 and then coupled to the tubular portion 116. The cover portion 120 is formed with a rod insertion hole 120a that penetrates the cover portion 120 in the axial direction.

The piston 104 is housed inside the cylinder 102. The piston 104 includes a columnar first piston head 122, a columnar second piston head 124, and a connecting portion 126 that connects the first piston head 122 and the second piston head 124. Even if the connecting portion 126 is integrally formed with the first piston head 122 and the second piston head 124, the connecting portion 126 is formed separately from at least one of the first piston head 122 and the second piston head 124 and is connected to the connecting portion 126. May be good. The piston 104 is housed in the cylinder 102 so that the first piston head 122 is located on the bottom 118 side and the second piston head 124 is located on the cover 120 side.

Due to the piston 104, the space inside the cylinder 102 is divided into a first cylinder chamber 128 located on the opposite side (that is, the bottom 118 side) of the piston 104 (specifically, the first piston head 122) from the rod 106. It is partitioned into a second cylinder chamber 130 located on the rod 106 side (that is, the cover portion 120 side) with respect to the piston 104 (specifically, the second piston head 124). The cylinder portion 116 includes a first port 132 for supplying and discharging compressed gas to and from the first cylinder chamber 128, and a second port 134 for supplying and discharging compressed gas to and from the second cylinder chamber 130. Is formed.

An air pad 162 as a hydrostatic air bearing is provided on the outer peripheral surface 122a of the first piston head 122. The air pad 162 is provided with an air supply hole (not shown). Through the air supply holes, compressed air supplied from an air supply system (not shown) is supplied to the first gap 136, which is a gap between the inner peripheral surface 116b of the cylinder portion 116 and the outer peripheral surface 122a of the first piston head 122. NS. As a result, a high-pressure gas layer is formed in the first gap 136, and the air pad 162 and thus the first piston head 122 rise from the cylinder 102.

The rod 106 is an elongated member, which is inserted into the rod insertion hole 120a, one end of which is connected to the piston 104, and the other end of which protrudes to the outside of the cylinder 102. The rod 106 may be formed integrally with the piston 104, or may be formed separately from the piston 104 and then coupled to the piston 104. The rod 106 has a polygonal (for example, rectangular) cross section.

The pressure adjusting unit 110 adjusts the pressure in the first cylinder chamber 128 and the pressure in the second cylinder chamber 130. The pressure adjusting unit 110 supplies air decompressed and adjusted by a servo valve to the first cylinder chamber 128 via the first port 132, and supplies constant pressure air to the second cylinder chamber 130 via the second port 134. .. The pressure adjusting unit 110 is not limited to such a configuration, and for example, the pressure of the air supplied to the first cylinder chamber 128 and the pressure of the air supplied to the second cylinder chamber 130 are controlled by a servo valve. It may be configured to adjust.

The rotation drive source 112 is a drive source that rotates the rod 106 in the circumferential direction within a predetermined angle range. In particular, the rotation drive source 112 has a rotation axis coaxial with the central axis of the rod 106 to be rotationally driven, and thus directly rotates the rod 106 without a transmission mechanism. As a result, as compared with the case where the rotation of the rotation drive source having a rotation axis non-coaxial with the central axis of the rod is transmitted by the belt to rotate the rod as in the conventional actuator as described in Patent Document 1. The positioning accuracy of the rod 106 in the rotation direction is improved, and the responsiveness is also improved.

The rotary drive source 112, in the illustrated example, is a direct drive motor and includes a rotor 144 and a stator 146 that surrounds the rotor 144. The rotor 144 is a magnet and is fixed to the outer periphery of the first ring member 166. The first surrounding member 166 has an inner peripheral surface 166a having a polygonal cross section corresponding to the rod 106, and an outer peripheral surface 166b having a circular cross section. The first ring member 166 surrounds the rod 106 and is fixed to the rod 106. The stator 146 is provided with a coil 160 so as to face the rotor 144 in the radial direction. A magnetic field is generated around the coil 160 by supplying a drive current to the coil 160, and the rotor 144 and thus the rod 106 and the piston 104 are rotationally driven by the electromagnetic action between the coil 160 and the rotor (magnet) 144 facing the coil 160. NS. Although the first ring member 166 is separate from the rod 106, the first ring member 166 may be formed integrally with the rod 106. That is, the first surrounding member 166 may be a part of the rod 106.

The support portion 108 is provided between the cylinder 102 and the rotary drive source 112. The support portion 108 supports the rod 106 so as to be slidable in the axial direction and rotatably in the circumferential direction. The support portion 108 includes a housing 148, a single bearing 150 housed in the housing 148, and a second ring member 168 that is internally fitted in the bearing 150 and surrounds the rod 106.

The housing 148 is a tubular member, and the hollow portion 148a thereof has a circular cross section. The outer shape of the housing 148 is not particularly limited, but has a rectangular cross section. The hollow portion 148a of the housing 148 is connected to the cylinder portion 116 so that the hollow portion 148a is coaxial with the central axis of the cylinder 102.

The bearing 150 is a ball bearing in the illustrated example, and is arranged inside the housing 148 so that its central axis is coaxial with the central axis of the cylinder 102.

The second ring member 168 has an inner peripheral surface 168a having a polygonal cross section corresponding to the rod 106, and an outer peripheral surface 168b having a circular cross section corresponding to the inner ring 150a of the bearing 150. An air pad 164 as a hydrostatic air bearing is provided on the outer peripheral surface 106a of the rod 106 so as to face the inner peripheral surface 168a of the second ring member 168. The air pad 164 is provided with an air supply hole (not shown). Through the air supply holes, compressed air supplied from an air supply system (not shown) is supplied to the second gap 138, which is a gap between the inner peripheral surface 168a of the second ring member 168 and the outer peripheral surface 106a of the rod 106. NS. As a result, a high-pressure gas layer is formed in the second gap 138, and the air pad 164 and thus the rod 106 rise from the second surrounding member 168. The second surrounding member 168 receives a rotational force from the rod 106 via the high-pressure gas layer formed in the second gap 138, and rotates together with the rod 106 in a non-contact state with the rod 106.

The piston 104 and the rod 106 are slidably supported in the axial direction (left-right direction in FIG. 1) in a non-contact state with the cylinder 102 and the support portion 108 via air pads 162 and 164 as hydrostatic air bearings. NS. As a result, the movement of the piston 104 and the rod 106 becomes smooth, and highly accurate positioning and force control become possible. In FIG. 1, the first gap 136 and the second gap 138 are exaggerated, but in reality, the first gap 136 and the second gap 138 are, for example, about several microns.

Subsequently, although not shown, the actuator 100 of the present embodiment includes a position detection unit that detects the axial position and the rotational position of the rod 106 or the piston 104. The position detection unit detects the axial position and the rotational position of the rod 106 or the piston 104 at a predetermined cycle, and indicates an axial position signal indicating the detected axial position and a rotational position signal indicating the detected rotational position. Is output to the controller 114.

The controller 114 outputs a movement command to the pressure adjusting unit 110 so that there is no difference between the axial position signal and the position command value from the outside. The pressure adjusting unit 110 drives the servo valve based on the movement command and controls the positioning of the rod 106 in the axial direction.

Further, the controller 114 outputs a rotation command to the rotation drive source 112 so that there is no difference between the rotation direction position signal and the position command value from the outside. The rotation drive source 112 is driven based on the rotation command, and performs positioning control in the rotation direction of the rod 106.

Further, when performing load control, the controller 114 informs the pressure adjusting unit 110 so that there is no difference between the load generated by the pressure difference between the first cylinder chamber 128 and the second cylinder chamber 130 and the load command from the outside. The load command is output. The pressure adjusting unit 110 drives the servo valve based on the load command, and performs load control for applying a load (force) to the rod 106.

The above is the basic configuration of the actuator 100. Subsequently, the configuration of the support portion 108 will be described in more detail.

In reality, it is not easy to assemble the support portion 108, that is, the central axis of the bearing 150 so as to be coaxial with the central axis of the cylinder 102. The housing 148 is formed so that the hollow portion 148a has a perfect circular cross section, and the housing 148 is formed so that the central axis of the housing 148 (more specifically, the hollow portion 148a) is coaxial with the central axis of the cylinder 102. The bearing 150 must be connected to the 102 and the bearing 150 must be arranged so that the central axis of the bearing 150 is coaxial with the central axis of the housing 148 and the cylinder 102. In reality, there may be an error in these, and as a result, the piston 104 may bite (contact) the cylinder 102.

On the other hand, in a conventional actuator as described in Patent Document 1, since the rotation of a rotation drive source having a rotation axis non-coaxial with the rod is transmitted to the rod by a belt, the rod is orthogonal to the axial direction by the belt. Pulled in the direction. In order to counter the force pulled in the direction orthogonal to the axial direction, the conventional actuator is required to have high rigidity in the support portion that supports the rod. On the other hand, in the present embodiment, as described above, since the rod 106 is rotated by the rotation drive source 112 having a rotation axis coaxial with the rod 106, the rod 106 is not pulled in the direction orthogonal to the axial direction. .. Therefore, the rigidity required for the support portion 108 is relatively low.

Therefore, in the present embodiment, the support portion 108 is not provided with the plurality of bearings 150, but is intentionally provided with only one bearing 150 as described above. The bearing 150 is configured to allow the central axis of the rod 106 to deviate from the central axis of the bearing 150 within a range that does not impair the function as a bearing in design. Here, when the central axis of the rod 106 deviates from the central axis of the bearing 150, the rod 106 moves slightly in parallel in the radial direction, and the central axis of the rod 106 and the central axis of the bearing 150 do not match (heavy weight). It means that the rod 106 is slightly tilted and the central axis of the rod 106 is tilted with respect to the central axis of the bearing 150. Allowing the deviation may be realized, for example, by intentionally increasing the internal clearance of the bearing 150. As a result, even if the central axis of the bearing 150 is slightly deviated from the central axis of the housing 148 or the cylinder 102, the bearing 150 is absorbed by allowing the deviation, and the piston 104 and the rod 106 are prevented from being gnawing. NS. In addition, the actuator 100 can be relatively easily assembled, and the assembly cost can be reduced.

The actuator 100 configured as described above is used, for example, in a die bonding process or a mounting process of a semiconductor chip. Specifically, a tool for holding the semiconductor chip in the semiconductor manufacturing apparatus slides (moves) the rod 106 attached to the tip in the axial direction. Alternatively, the rod 106 is rotated within a required angle range. As a result, the semiconductor chip can be mounted on a mounting surface such as a lead frame or a substrate.

(Second Embodiment)
FIG. 2 is a diagram schematically showing the actuator 200 according to the second embodiment. FIG. 2 corresponds to FIG. Hereinafter, the actuator 200 will be described focusing on the differences from the actuator 100 according to the first embodiment.

The actuator 200 includes a cylinder 102, a piston 104, a rod 106, a support portion 208, a pressure adjusting portion 110, a rotation drive source 112, and a controller 114. That is, in the present embodiment, the support portion 208 is provided instead of the support portion 108. Further, in the present embodiment, the rod 106 has a circular cross section.

The support portion 208 allows the rod 106 to be slidable in the axial direction and rotatable in the circumferential direction in a non-contact state, and further allows the central axis of the rod 106 to be displaced with respect to the central axis of the support portion 208. Support to do. In the illustrated example, the support 208 comprises a housing 148, a magnet 252 fixed to the outer peripheral surface of the rod 106, and a plurality of coils 254 provided in the housing 148 so as to surround the magnet 252. The rod 106 is supported by magnetic force. A plurality of coils may be provided on the outer peripheral surface of the rod 106, and a magnet may be fixed to the inner peripheral surface of the housing 148 so as to surround the plurality of coils.

Further, the support portion 208 includes a plurality of sensors (only one sensor is shown in FIG. 2) 256 for measuring the distance between the rod 106 and the housing 148. The plurality of sensors 256 are arranged, for example, 45 degrees apart in the circumferential direction. The plurality of sensors 256 measure the distance between the rod 106 and the housing 148 at a predetermined cycle, and transmit the measurement result to the controller 114.

Based on the measurement result, the controller 114 controls the magnitude and direction of the current flowing through the coil so that the rod 106 is fastened at a position where the central axis of the rod 106 overlaps the central axis of the support portion 208 and the cylinder 102. Since such a control method is known, further description thereof will be omitted.

The support portion 208 is not limited to such a configuration. The support portion 208 may support the rod 106 in a non-contact manner, and may be configured to support the rod 106 in a non-contact manner by forming a hydrostatic air bearing with the rod 106, for example.

According to the actuator 200 of the present embodiment, the same effect as that of the actuator 100 of the first embodiment can be obtained.

Further, in the present embodiment, the rod 106 is supported in a non-contact manner, but when the rod 106 is supported in a non-contact manner, when the rod 106 rotates, its central axis becomes the central axis of the support portion 208 or the cylinder 102. Cylinder. In this state, for example, if the rod 106 is rotated at a high rotation speed, the rod 106 vibrates. On the other hand, according to the present embodiment, the support portion 208 is controlled so as to fasten the central axis of the rod 106 at a position overlapping the central axis of the support portion 208 and thus the cylinder 102. That is, the support portion 208 is controlled so as to suppress the deviation of the central axis of the rod 106 with respect to the central axis of the support portion 208 and the cylinder 102. In this case, the deviation between the central axis of the rod 106 and the central axis of the support portion 208 and the cylinder 102 is suppressed. As a result, vibration of the rod 106 is suppressed even if the rod 106 is rotated at a high rotation speed, for example. In other words, since the deviation is suppressed, the rod 106 can be rotated at a higher rotation speed, that is, the rod 106 can be positioned in the rotation direction in a shorter time.

Further, in the present embodiment, the piston 104 and the rod 106 are supported by the first hydrostatic air bearing 140 and the support portion 208 so as to be slidable in the axial direction. In this case, since the hydrostatic fluid bearing is not required in the second gap 138, the cost can be reduced accordingly.

The present invention has been described above based on the embodiments. This embodiment is an example, and it is understood by those skilled in the art that various modifications are possible for each of these components and combinations of each processing process, and that such modifications are also within the scope of the present invention. be.

100,200 actuators, 102 cylinders, 104 pistons, 106 rods, 112 rotary drive sources, 108,208 supports.

Claims (5)

Cylinder and
A piston that is slidably housed in the cylinder,
A rod extending from the piston and projecting to the outside of the cylinder,
A rotary drive source having a rotary shaft coaxial with the rod, which drives the rod to rotate,
A support portion that rotatably supports the rod and
With
The actuator is characterized in that the support portion is configured to allow the central axis of the rod to deviate from the central axis of the support portion. The actuator according to claim 1, wherein the support portion supports the rod in a non-contact manner and is controlled so as to suppress a deviation of the central axis of the rod with respect to the central axis of the support portion. The actuator according to claim 2, wherein the support portion supports the rod in a non-contact manner by a magnetic force and is controlled so as to suppress a deviation of the central axis of the rod with respect to the central axis of the support portion. .. The first aspect of the present invention, wherein the support portion includes a bearing configured to support the rod so as to allow the central axis of the rod to deviate from the central axis of the support portion. Actuator. The actuator according to claim 4, wherein the bearing is a single ball bearing.

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