JP2018123927A - Rotary actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary actuator which has a simple structure, can be reduced in a radial dimension and can rotate at a high speed.SOLUTION: A rotary actuator comprises: a boss member 2 formed with a cylindrical slide surface therein; a rotary head 3 having a cylindrical shape and formed with a slide surface on an outside surface; an air drive type actuator 4 installed on a top surface of the rotary head 3; an actuator air supply passage supplying air from the boss member 2 to the rotary head 3 and supplying the air from the rotary head 3 to the actuator 4; and a floating air supply passage supplying the air from the boss member 2 to a gap between the slide surface 2A of the boss member 2 and the slide surface 3A of the rotary head 3. The air is partially supplied from the air supply passage and is introduced between the slide surface of the boss member and the slide surface of the rotary head, so that the rotary head 3 rotates in a state of air-floating. Therefore, high-speed rotation becomes possible.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotary actuator. More specifically, the present invention relates to an air-driven rotary actuator.

The rotary actuator is a device that operates an actuator by sending a working medium to the actuator via a rotary joint.
The rotary joint itself is a mechanism member that sends a working medium such as hydraulic oil or air from the fixed member side to the rotating member side, and is known as shown in Patent Document 1.

As a kind of rotary actuator, there is a technique of Patent Document 2 showing a processing tool for rotating a blade. In this prior art, a path for taking in air as a working medium from an outer stationary member to an inner rotating member is formed. However, the support shaft for the stationary member of the rotating member is borne by the bearing.
As described above, the conventional technique using the bearing has a drawback that the structure is complicated and the apparatus has a large radial dimension.

  Therefore, a technology for supporting the rotating shaft with a bush using a material having high slipperiness has been developed. This technique simplifies the structure and reduces the size, but the support by the bush is limited by friction and cannot increase the rotational speed. Generally, the limit was several hundred rpm. If the maximum number of revolutions was to be increased, the load would have to be considerably lighter, and the lifetime revolution number was not long.

  Therefore, there has never been a rotary actuator that can be operated for a long time under a normal load and that enables high-speed rotation.

JP 2005-249008 A JP-A-9-29529

  In view of the above circumstances, an object of the present invention is to provide a rotary actuator that has a simple structure, can have a small radial dimension, and can rotate at high speed over a long period of time even under a normal load.

A rotary actuator according to a first aspect of the present invention is a boss member having a cylindrical sliding surface formed therein, a rotating member, a rotating head having a cylindrical shape and a sliding surface formed on an outer surface, and the rotating head An air-driven actuator attached to the top surface of the actuator, an air supply path for an actuator that supplies air from the boss member to the rotary head, and further supplies air from the rotary head to the actuator, and from the boss member A levitation air supply path for supplying air to a gap between the sliding surface of the boss member and the sliding surface of the rotary head is provided.
A rotary actuator according to a second aspect is the porous actuator according to the first aspect, wherein the rotary actuator is formed on the exit side of the levitation air supply path formed in the boss member and at a location facing the sliding surface of the rotary head. An annular ring is fitted.
The rotary actuator of a third invention is characterized in that, in the second invention, a gap between the sliding surface of the boss member and the sliding surface of the rotary head is 5 to 15 μm.

According to the first invention, since the air from the air supply path for levitation is guided between the sliding surface of the boss member and the sliding surface of the rotary head, the rotary head rotates in a state where the air floats. For this reason, since the rotary head can be rotated without friction, high-speed rotation is possible and a long life can be achieved. In addition, since there is no need to insert mechanical parts such as bushes and bearings between the rotary head and the boss member, the radial dimension can be reduced and a simple configuration can be achieved.
According to the second aspect of the invention, when the air sent through the levitation air supply path is ejected from a large number of holes in the ring, the air is uniformly filled between the sliding surface of the rotating head and the sliding surface of the boss member. Stable air floating rotation of the rotary head.
According to the third invention, since the gap between the sliding surface of the boss member and the sliding surface of the rotary head is as small as 5 to 20 μm, it is difficult for air to leak out, and the air floating rotation of the rotary head is prevented. Stabilize.

It is a longitudinal cross-sectional view of the rotary actuator which concerns on one Embodiment of this invention. FIG. 2 is a top view of a boss member and a rotary head shown in FIG. 1. It is explanatory drawing of the air supply path for levitation | floating. It is explanatory drawing of the air supply path for actuators. It is explanatory drawing of the air supply point at the time of rotation of a rotating head.

Next, an embodiment of the present invention will be described with reference to the drawings.
First, based on FIG. 1 and FIG. 2, the basic structure of the rotary actuator A according to an embodiment of the present invention will be described.
The rotary actuator A includes a boss member 2, a rotary head 3 that rotates within the boss member 2, and an actuator 4 that is attached to the rotary head 3.

Reference numeral 1 denotes a fixed plate, which includes a lower fixed plate 1a and an upper fixed plate 1b. A cylindrical boss member 2 is fixed to the fixed plate 1. However, it is not fixed at all and is fixed so as to allow a slight displacement. Specifically, the pin 31 fixed to the upper fixing plate 1b is inserted into the hole 32 formed in the boss member 2, and the hole 32 has a slightly larger diameter than the pin 31, so that the boss member A slight displacement of 2 is allowed. The boss member 2 is a stationary member in the sense that it does not move greatly.
A cylindrical sliding surface is formed inside the boss member 2 as will be described later.

The rotary head 3 is a cylindrical member, and a sliding surface 3A is formed on the outer surface thereof.
The rotary head 3 has an integrally formed shaft 5. A separate shaft 5 may be coupled to the rotary head 3.
The shaft 5 receives rotational power from the outside and rotates the rotary head 3. Since the shaft 5 is supported by a bearing, the rotary head 3 rotates at a fixed position.

  As will be described later, the rotary head 3 rotates in the air levitation state in the boss member 2. However, since the rotary head 3 is fixed in position by the bearing support of the shaft 5, the entire sliding surface necessary for air levitation is provided. The uniform gap is ensured by a slight displacement of the boss member 2. The slightly loose attachment of the boss member 2 by the pin 31 and the hole 32 described above is a means for realizing this uniform clearance.

An actuator 4 is attached to the top surface (upper surface in FIG. 1) of the rotary head 3 via an attachment plate 6.
Any actuator 4 can be used as long as it is an air drive type actuator. Although the illustrated actuator is an air cylinder, the invention is not limited to this, and an air swing motor or the like may be used.

There may be one actuator 4 or a plurality of actuators. In the illustrated embodiment, six air cylinders are arranged radially from the center of the rotary head 3.
Both the expansion operation and the reduction operation of the air cylinder may be operated by air supply / discharge, and either one of the expansion operation or the reduction operation may be operated by air supply / discharge.

  As shown in FIGS. 2 and 4, the sliding surface 2 </ b> A of the boss member 2 and the sliding surface 3 </ b> A of the rotating head 3 face each other, and are in sliding contact with each other while the rotating head 3 is rotating. The gap g between the sliding surfaces 2A and 3A is an important element in the present invention, and the gap g is in the range of 5 to 20 μm, preferably 8 to 15 μm, and most preferably 10 μm.

  The numerical range of the gap g has the meaning of causing the rotary head 3 to float by air supplied into the gap g as will be described later. If the gap is less than 5 μm, air cannot float and contact resistance increases and the rotary head 3 becomes difficult to rotate. On the other hand, if it exceeds 20 μm, the air is removed, the contact resistance is increased, and the rotary head 3 is difficult to rotate.

When the gap g is in the range of 5 to 20 μm, the air supplied between the sliding surface 3A of the rotary head 3 and the sliding surface 2A of the boss member 2 causes some leakage, while the sliding surface 2A, Fill between 3A. For this reason, the sliding surfaces 2A and 3A can be rotated in a state where the rotary head 3 is floated on air without causing physical contact.
The air floating rotation of the rotary head 3 described above is more stable when the gap is in the range of 8 to 15 μm, and is most stable when the gap is 10 μm.

  There are no particular restrictions on the outer diameter of the rotary head 3 and the inner diameter of the boss member 2 to which the preferred range of the gap g is applied, but it is suitable for the range of 50 to 100 mm.

Next, the levitation air supply path will be described with reference to FIGS.
An elbow pipe 14 is attached to the boss member 2, and an internal passage 15 is formed in the cross section of the boss member 2. The internal passage 15 communicates with the elbow pipe 14 and is divided into upper and lower portions and is formed so as to communicate with the sliding surface 2 </ b> A inside the boss member 2.

  On the sliding surface 2A on the inner side of the boss member 2, an annular step is formed at two upper and lower openings of the internal passage 15, and an annular ring 25 is fitted to the step. The ring 25 is made of a sintered metal having a porous character.

  Both the upper and lower rings 25 are in sliding contact with the sliding surface 3 </ b> A of the rotary head 3. Air is supplied to the back surface of the ring 25 from the internal passage 15, and the air is dispersed through a large number of holes in the ring 25 to fill the gap g between the sliding surface 2 </ b> A and the sliding surface 3 </ b> A. For this reason, since the air is filled evenly, the air floating rotation of the rotary head can be stably performed.

Next, an actuator air supply path for supplying operating air to the actuator 4 will be described with reference to FIGS.
The boss member 2 is formed with an arbitrary number (six in the drawing) of holes 11 extending in the radial direction, and elbow pipes 12 and 16 connected to external pipes extending from an air supply source are attached to the outer ends thereof. ing. Of these six elbow tubes, four are for air supply and two are for pressure measurement. Note that the number of elbow tubes 12 for supplying air is not limited to four, and any number of three or less or any number of five or more can be selected.

  On the other hand, an annular groove 21 is formed on the outer periphery of the rotary head 3, and an internal through hole 22 communicating with the groove 21 is formed inside the rotary head 3. Further, a port 23 is formed on the top surface of the rotary head 3, and the internal through hole 22 communicates with the port 23.

As clearly shown in FIGS. 4 and 5, the groove 21 formed on the outer periphery of the rotary head 3 includes an upper groove 21a and a lower groove 21b. Accordingly, the hole 11 formed in the boss member 2 also includes an upper hole 11a and a lower hole 11b.
The internal through hole 22 formed in the rotary head 3 is also divided into a through hole 22a communicating with the upper groove 21a and a through hole 22b communicating with the lower groove 21b.

  Therefore, as shown in FIGS. 5 (A) and 5 (B), while the rotary head 3 is rotating, some of the plurality of actuators 4 have air through the upper hole 11a and the upper groove 21a. Air is supplied to the remaining units through the lower hole 11b and the lower groove 21b.

  According to the present embodiment, since the air is guided from the air supply path for levitation between the sliding surface 2A of the boss member 2 and the sliding surface 3A of the rotating head 3, the rotating head 3 moves the air in the boss member 2. Rotates in a floating state. Since the actuator attached to the rotary head 3 is operated by the air supplied from the actuator air supply path, the actuator can perform an expansion / contraction operation while rotating as the rotary head 3 rotates.

  The actuator 4 of the present embodiment operates along with the rotation of the rotary head 3. For such applications, there is a workpiece re-chucking chuck in a machine tool, but the invention is not limited to this.

  The upper limit of the rotational speed of the rotary head 3 is not particularly limited, but according to the present invention, it can be sufficiently realized at about 3000 rpm. Moreover, since no wear occurs, a long life can be achieved.

  According to the embodiment of the present invention, since it is not necessary to insert mechanical parts such as a bearing between the rotary head 3 and the boss member 2, the radial dimension can be reduced and a simple configuration can be achieved.

2 Boss member 3 Rotating head 4 Actuator 6 Mounting plate 11 (11a, 11b) Hole 15 Internal passage 21 (21a, 21b) Groove 25 Ring 31 Pin 32 Hole

A rotary actuator according to a first aspect of the present invention is a boss member having a cylindrical sliding surface formed therein, a rotating member, a rotating head having a cylindrical shape and a sliding surface formed on an outer surface, and the rotating head An air-driven actuator attached to the top surface of the actuator, an air supply path for an actuator that supplies air from the boss member to the rotary head, and further supplies air from the rotary head to the actuator, and from the boss member A floating air supply passage for supplying air to a gap between the sliding surface of the boss member and the sliding surface of the rotary head, and the sliding surface of the boss member slides on the rotary head. It is characterized by being attached to the fixed plate via loose attachment means for maintaining a uniform gap with the moving surface .
A rotary actuator according to a second aspect is the porous actuator according to the first aspect, wherein the rotary actuator is formed on the exit side of the levitation air supply path formed in the boss member and at a location facing the sliding surface of the rotary head. An annular ring is fitted.
The rotary actuator of a third invention is characterized in that, in the second invention, a gap between the sliding surface of the boss member and the sliding surface of the rotary head is 5 to 15 μm.

According to the first invention, the following effects are obtained.
a) Since air from the air supply path for levitation is guided between the sliding surface of the boss member and the sliding surface of the rotary head, the rotary head rotates in a state where the air floats. For this reason, since the rotary head can be rotated without friction, high-speed rotation is possible and a long life can be achieved.
b) Since the boss member is attached to the fixed plate through loose attachment means, the gap between the sliding surface of the boss member and the sliding surface of the rotating head is kept uniform, and the rotating head rotates. Can be performed stably.
According to the second aspect of the invention, when the air sent through the levitation air supply path is ejected from a large number of holes in the ring, the air is uniformly filled between the sliding surface of the rotating head and the sliding surface of the boss member. Stable air floating rotation of the rotary head.
According to the third aspect of the present invention, the clearance between the sliding surface of the boss member and the sliding surface of the rotary head is as small as 5 to 15 μm. Is stable.

Claims (3)

A boss member having a cylindrical sliding surface formed therein;
A rotating member, a rotating head having a cylindrical shape and a sliding surface formed on the outer surface;
An air-driven actuator attached to the top surface of the rotary head;
An air supply path for an actuator for supplying air from the boss member to the rotary head, and further supplying air from the rotary head to the actuator;
A rotary actuator, comprising: a floating air supply path for supplying air from the boss member to a gap between a sliding surface of the boss member and a sliding surface of the rotary head. An annular ring made of a porous material is fitted on the exit side of the floating air supply path formed in the boss member and facing the sliding surface of the rotary head. The rotary actuator according to claim 1. The rotary actuator according to claim 2, wherein a gap between the sliding surface of the boss member and the sliding surface of the rotary head is 5 to 15 μm.

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