JP4234874B2 - Frictionless air cylinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of an air cylinder, in particular, a frictionless air cylinder having no sliding resistance when moving a piston.
[0002]
[Prior art]
Conventionally, air cylinders have been widely used as drive actuators for industrial equipment and robots. The general air cylinder adjusts the pressure of the drive air supplied to the pressure chambers formed on both sides of the piston that can move inside the cylinder tube whose inner wall is movable (generally, the air pressure is applied to one of the pressure chambers). And the air in the other pressure chamber is exhausted) to move the piston in a desired direction at a desired timing. A rod is connected to the piston, and a mechanical element such as a table or an arm to be driven connected to the tip of the rod is desired by moving forward and backward in the axial direction of the cylinder tube according to the movement of the piston. Can be performed.
[0003]
[Problems to be solved by the invention]
However, in the case of air cylinders, the inner wall of the cylinder tube and the outer periphery of the piston are very concentric and have a slight gap between them in order to compensate for stable operation while avoiding leakage of drive air. Need to be processed to slide. As a result, there is a problem that manufacturing cost increases because high processing accuracy is required. Since the cylinder tube and piston are generally made of metal such as aluminum, the cylinder tube and piston undergo thermal expansion and contraction due to changes in ambient temperature, and the cylinder tube and piston face each other (contact state). Changes, leading to an increase or decrease in sliding resistance, resulting in variations in piston operation. Further, since there is sliding resistance between the cylinder tube and the piston, there is a problem that the drive energy is lost and the response to the operation signal is lowered.
[0004]
The present invention has been made in view of the above-described conventional problems, and its purpose is not to require high machining accuracy, and is not affected by changes in the ambient temperature, and further to drive energy loss and operation signals. It is an object of the present invention to provide a frictionless air cylinder in which there is no decrease in responsiveness.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a cylinder tube, a piston capable of moving in the axial direction within the cylinder tube by air pressure control, and having ring-shaped flanges on both end surfaces, an outer peripheral surface of the piston, A ring that is loosely fitted in a non-sealed space formed by a flange and an inner wall of the cylinder tube and moves together with the piston, and a plurality of rings are formed on the outer peripheral surface at a predetermined interval to eject air toward the inner wall of the cylinder tube A centering ring that has an air outlet and aligns the cylinder tube, and an air supply unit that supplies alignment air to the centering ring are included.
[0006]
The aligning ring is loosely fitted to the piston so as to be movable in a direction perpendicular to the moving direction of the piston, and aligning air is supplied to the cylinder tube from a plurality of outlets formed on the outer peripheral surface of the aligning ring. By ejecting toward the inner wall, the piston moves in a direction perpendicular to the moving direction of the piston, and the whole piston is aligned. At this time, the air pressure ejected from the outer peripheral surface of the aligning ring is set higher than the operating pressure for moving the piston.
[0007]
According to this configuration, the cylinder tube and the aligning ring are always in a non-contact state (floating state) by the aligning air, and the piston including the aligning ring is always in contact with the cylinder tube by the aligning air. To be aligned. Therefore, there is no contact resistance with respect to the cylinder tube during the operation of the piston, so that there is no loss of driving energy or responsiveness. Further, since the cylinder tube, the piston, and the aligning ring are not in contact with each other, high concentricity is not required, that is, high machining accuracy is not required. In addition, the cylinder tube, piston, and alignment ring are always non-contact, so even if thermal expansion or contraction occurs due to changes in ambient temperature, the operation of the piston is not affected. Since the centering operation is performed in a floating state, stable operation of the piston can be secured.
[0008]
In order to achieve the above object, the present invention is characterized in that, in the above configuration, the air outlet is formed in a recess formed at a predetermined interval on an outer peripheral surface of the aligning ring.
[0009]
According to this structure, since the action area of the blowing air with respect to a cylinder tube inner wall can be expanded, stable and favorable alignment operation | movement can be performed.
[0010]
In order to achieve the above object, according to the present invention, in the above configuration, the aligning ring has a through hole along a moving direction of the piston, and the flange has a ring groove at a height facing the through hole. It is characterized by having.
[0011]
According to this configuration, the pressure is the same at both ends of the aligning ring, and even if air pressure for piston movement (drive) is applied to the aligning ring, the aligning ring is urged against the flange. Therefore, the alignment operation of the alignment ring can be performed satisfactorily.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention (hereinafter referred to as embodiments) will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a main part of a frictionless air cylinder 10 of the present embodiment. Inside the cylinder tube 12 having a cylindrical inner wall, a piston 16 fixed to a rod 14 indicated by a well-known air bearing (not shown) is movable in the axial direction (arrow A direction) of the cylinder tube 12. Has been placed. Further, flanges 18 are disposed on both end faces of the piston 16, and pressure chambers 20 and 22 are formed on the left and right sides of the piston 16. Then, the air for driving the piston 16 is supplied to the pressure chamber 20 or the pressure chamber 22 via a regulator or a valve from an air supply device (not shown), so that a differential pressure is generated between the pressure chamber 20 and the pressure chamber 22. The piston 16 moves with the rod 14 in the desired direction. For example, when driving air is supplied to the pressure chamber 20, the pressure chamber 22 is in an exhaust state, and the piston 16 moves in the left direction in the figure. Conversely, when driving air is supplied to the pressure chamber 22, the pressure chamber 20 is in an exhaust state, and the piston 16 moves to the right in the drawing. As a result, the rod 14 moves back and forth, and mechanical elements (not shown) such as a table and an arm connected to the rod 14 are driven, and the equipment and robot on which the frictionless air cylinder 10 is mounted are driven.
[0013]
The characteristic matter of this embodiment is that the piston 16 maintains a non-contact state with respect to the inner wall of the cylinder tube 12 and the moving body including the piston 16 performs a centering operation with respect to the cylinder tube 12. is there.
[0014]
2A and 2B are sectional views illustrating the piston 16 and the surrounding structure. FIG. 2A and FIG. 2B show the cross-sectional positions shifted.
[0015]
As shown in FIGS. 1 and 2A, flanges 18 are fixed to both ends of the piston 16, and a non-sealed space 24 is formed by the outer peripheral surface of the piston 16, the flange 18, and the inner wall of the cylinder tube 12. is doing. A ring-shaped aligning ring 26 is arranged in the non-sealed space 24 in a loosely fitted state (a rattling state). That is, the aligning ring 26 is freely moved in the non-sealed space 24 at least in a direction (arrow B direction) orthogonal to the movement direction (arrow A direction) of the piston 16 by aligning air described later. It arrange | positions so that alignment operation may be performed with respect to the inner wall face of the cylinder tube 12. FIG. Note that a predetermined gap is formed between both end faces of the aligning ring 26 and the flange 18 so that the aligning operation (movement) of the aligning ring 26 in the direction of arrow B is easily performed.
[0016]
A plurality (for example, three or five, preferably an odd number) of concave portions 26a are formed on the outer peripheral surface of the aligning ring 26 at equal intervals. An air ejection port 28 for ejecting commercial air is formed. The air ejection port 28 extends inward of the alignment ring 26 and receives compressed air supplied from an alignment air supply port 30 (air supply unit) formed on the surface of the piston 16. Spouts toward the inner wall. The alignment air supply port 30 is connected to an air supply source (not shown) via an air flow path 32 formed inside the rod 14, and at least while the piston 16 is moving in the arrow A direction, Alignment air at a predetermined pressure is always supplied. A groove 34 is formed in the outer peripheral surface of the piston 16, and at least one alignment air supply port 30 is connected to the groove 34 so that alignment air is supplied to the entire groove 34. .
[0017]
In FIG. 2A, the gap between the cylinder tube 12 and the alignment ring 26 is, for example, 5 μm in the alignment state in which the alignment air is blown out, and the clearance between the alignment ring 26 and the flange 18 is, for example, 2 μm. The alignment air passes between the cylinder tube 12 and the flange 18 and is discharged to the pressure chamber 20 or the pressure chamber 22 side.
[0018]
Next, the operation of the aligning ring 26 will be described. In the operable state of the frictionless air cylinder, a predetermined pressure (for example, 5 kg / cm ² ) is always supplied to the air flow path 32, and air is ejected from the alignment air supply port 30 and supplied to the groove 34. Yes. As a result, alignment air is constantly ejected from the air ejection port 28 toward the inner wall surface of the cylinder tube 12. In the present embodiment, the tip of the air ejection port 28 has a reduced diameter, and the air pressure is reduced to, for example, 3 kg / cm ² .
[0019]
At this time, for example, if the gap between the cylinder tube 12 and the aligning ring 26 is smaller than a predetermined amount (for example, 5 μm), the amount of leakage of the aligned aligning air decreases and the pressure in the recess 26a increases. Then, the aligning ring 26 is pushed downward in FIG. As described above, since a plurality of the recesses 26a including the air outlets 28 are arranged at equal intervals on the outer peripheral surface of the aligning ring 26, when the aligning ring 26 is pushed downward in FIG. On the opposite side, the gap between the cylinder tube 12 and the aligning ring 26 is reduced, and a pressing operation similar to that described above occurs. By performing this push-down operation all around the aligning ring 26, the aligning ring 26 is aligned with the cylinder tube 12, and as a result, the piston 16 is aligned with the cylinder tube 12. At this time, the cylinder tube 12 and the aligning ring 26 can be maintained in a non-contact state (floating state) by the blowing force of the aligning air, and the cylinder tube 12 and the aligning ring 26 are not in direct contact with each other. An air cylinder can be configured. Note that the pressure of the alignment air that is ejected from the air ejection port 28 is preferably set higher than the drive air pressure that actually drives the piston in the direction of arrow A. By setting the pressure of the aligning air high, an air seal can be formed between the cylinder tube 12 and the aligning ring 26, and the pressure loss of the drive air can be reduced.
[0020]
Thus, by arranging the aligning ring 26 that can maintain a non-contact state with the cylinder tube 12, the contact resistance with respect to the cylinder tube 12 during the operation of the piston 16 can be eliminated. As a result, drive energy loss and responsiveness are not reduced. Further, since the cylinder tube 12, the piston 16, and the aligning ring 26 are not in contact with each other, high concentricity is not required, that is, high processing accuracy is not required, so that the manufacturing cost can be reduced. Further, since the cylinder tube 12 and the alignment ring 26 are not in contact with each other at all times, the operation of the piston 16 is not affected even if the constituent members undergo thermal expansion or contraction due to a change in ambient temperature or the like. And since the aligning operation is always performed, the stable operation of the piston 16 can be ensured.
[0021]
By the way, in FIG. 2A, the alignment ring 26 protrudes slightly toward the cylinder tube from the flange 18 (for example, 1 mm). Therefore, the driving air for moving the piston 16 (flange 18) also acts on the alignment ring 26. As a result, the aligning ring 26 may be urged against the flange 18 disposed on the moving direction side of the piston 16 to obstruct the aligning operation of the aligning ring 26. Therefore, in the present embodiment, as shown in FIG. 2B, the aligning ring 26 is formed along the axial direction of the aligning ring 26 (moving direction of the piston 16) through the through-hole 36 (the air outlet port). The ring groove 38 is formed at a height (position) facing the through hole 36 of the flange 18. By providing the through-hole 36 in the aligning ring 26, the pressure is the same at both end faces of the aligning ring 26. Further, by forming the ring groove 38, the pressure is made uniform over the entire surface of the aligning ring 26. Thus, the biasing force due to the influence of the driving air of the piston 16 can be reduced. As a result, it is possible to avoid the aligning ring 26 from being strongly biased by the flange 18, and the aligning operation of the aligning ring 26 is not hindered. It is sufficient to form several through holes 36 (about 2 to 4) with respect to the aligning ring 26, and it is sufficient to form 2 to 3 ring grooves 38 as required.
[0022]
Thus, by providing the through hole 36, the floating state of the aligning ring 26 can be further improved, and a favorable aligning operation can be performed.
[0023]
In this way, the constructed frictionless air cylinder has no sliding resistance, so it can achieve high response to drive signals and high drive accuracy. For example, semiconductor manufacturing that requires high drive accuracy It is suitable for driving an XY table and a driving arm.
[0024]
In this embodiment, the rod 14 and the piston 16 are integrated, and the flange 18 is shown as a separate member with respect to the piston 16, but the rod 14 and the piston 16 may be separate members. The piston 16 and the flange 18 may be configured as an integrated member.
[0025]
【The invention's effect】
As described above, according to the present invention, the cylinder tube and the aligning ring are always in a non-contact state by the aligning air, and the piston including the aligning ring is always in the cylinder tube by the aligning air. Aligned against. Accordingly, there is no contact resistance to the cylinder tube during the operation of the piston, and drive energy loss and responsiveness are not reduced. In addition, since the cylinder tube, the piston, and the aligning ring are not in contact with each other, high concentricity is not required, that is, high processing accuracy is not required, so that the manufacturing cost can be reduced. In addition, since the cylinder tube and the aligning ring are not in contact with each other at all times, the piston operation is not hindered even if the constituent members undergo thermal expansion or thermal contraction due to a change in ambient temperature or the like. In addition, by forming a through-hole in the aligning ring and making the pressure at both ends of the aligning ring the same, the effect of piston drive air is reduced, achieving good aligning operation, and stable piston operation Can be secured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a frictionless air cylinder according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a piston and a surrounding structure of a frictionless air cylinder according to an embodiment of the present invention.
[Explanation of symbols]
10 Frictionless Air Cylinder, 12 Cylinder Tube, 14 Rod, 16 Piston, 18 Flange, 20, 22 Pressure Chamber, 26 Alignment Ring, 26a Recess, 28 Air Blowout Port, 36 Through Port, 38 Ring Groove.

Claims (3)

A cylinder tube (12), a piston (16) that is movable in the axial direction by air pressure control in the cylinder tube, and an air supply part (30) that sprays toward the inner wall of the cylinder tube,
Ring-shaped flanges (18) are provided on both end faces of the piston to form a non-sealed space (24) by the outer peripheral surface of the piston and the inner wall of the cylinder tube, and are adjusted in a loosely fitted state in the non-sealed space. A center ring (26) is arranged, and a plurality of air ejection ports (28) are formed at predetermined intervals on the outer peripheral surface of the alignment ring, and air is ejected from the air ejection port toward the inner wall of the cylinder tube. A frictionless air cylinder, characterized in that aligning air is supplied to the aligning ring for aligning the tube . The air cylinder according to claim 1,
The friction-less air cylinder according to claim 1, wherein the air outlet is formed in a recess (28) formed at a predetermined interval on an outer peripheral surface of the aligning ring. In the air cylinder according to claim 1 or 2,
The alignment ring has a through hole (36) along the moving direction of the piston, and the flange has a ring groove (38) at a height facing the through hole. Cylinder.

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