WO1997024544A1

WO1997024544A1 - Rotary valve

Info

Publication number: WO1997024544A1
Application number: PCT/IL1996/000193
Authority: WO
Inventors: Dov Sheffer
Original assignee: Rsr Adtec, Ltd.
Priority date: 1995-12-29
Filing date: 1996-12-29
Publication date: 1997-07-10
Also published as: AU1107697A; IL116618A0; IL116618A

Abstract

A rotary valve (100) including a stationary member (102) comprising an interfacial surface, and a rotatable member (104) attachable to a spindle (156) of a machine tool (150). The rotatable member (102) has an axis of rotation (130) and includes a rotatable surface in fluid communication with the interfacial surface of the stationary member (104), such that the working gas is conductible from the stationary member (102) to the rotatable member (104) via communication ports (122, 124) in the stationary member (102) and communication ports (134, 135) in the rotatable member (104) to actuate a portion of the machine tool (150), wherein the working gas flowing from the interfacial surface to the rotatable surface imparts a pressure therebetween, thereby creating a lubricating film therebetween.

Description

ROTARY VALVE FIELD OF THE INVENTION The present invention relates to rotary valves generally, and particularly to pneumatic rotary valves used with rotating machine tools

BACKGROUND OF THE INVENTION Pneumatic rotary valves used with rotating machine tools are known in the art In general, a prior art rotary valve includes a stationary member and a rotating member The stationary member is generally concentrically located within the rotating member, and typically includes two inlet ports, each in fluid communication with a source of compressed air

One of the inlet ports is typically in fluid communication with a first longitudinal channel formed in the rotating member, while the other inlet port is in fluid communication with a second longitudinal channel formed in the rotating member The channels are generally mutually parallel and are separated from each other by a thin wall. The two longitudinal channels thus provide two separate paths for the air flow. Air may flow through the first longitudinal channel in order to open the jaws of a chuck ofthe machine tool, for example, while air flowing through the second longitudinal channel may be used to close the jaws ofthe chuck

A disadvantage of the prior art rotary valve stems from the fact that the rotating member is inserted into the stationary member and a narrow gap separates the two members. During rotation, the rotating member may become increasingly hotter and expand, thereby increasing friction between the rotating and stationary members and possibly causing malfunction of the rotary valve. The construction is also generally prone to malfunction due to contamination by dirt and dust Only relatively small diameter bars may be inserted through the stationary and rotating members, thereby limiting the scope of use of the rotary valve In addition, the prior art valve may be prone to relatively large leaks of compressed air

SUMMARY OF THE INVENTION The present invention seeks to provide a novel rotary valve which allows a relatively large workpiece to extend therethrough and which allows attaining relatively higher 2 rotational speeds than prior art rotary valves The rotary valve of the present invention also has apparatus for controlling the air leak between the stationary and rotatable members

There is thus provided in accordance with a preferred embodiment of the present invention, a rotary valve including a stationary member comprising an interfacial surface, and a rotatable member attachable to a spindle of a machine tool, a portion of the machine tool being actuable by a working gas, the rotatable member having an axis of rotation and including a rotatable surface, the rotatable surface being in rotatable fluid communication with the interfacial surface of the stationary member, such that the working gas is conductable from the stationary member via the rotatable member to actuate the portion of the machine tool, wherein the working gas flowing from the interfacial surface to the rotatable surface imparts a pressure therebetween, thereby creating a lubricating film therebetween

In accordance with a preferred embodiment of the present invention, the axis of rotation is not parallel to and does not lie along the interfacial surface and the rotatable surface. Preferably the axis of rotation is generally peφendicular to the interfacial surface and the rotatable surface.

Further in accordance with a preferred embodiment of the present invention, there is provided a control device for controlling the rotatable fluid communication between the rotatable surface and the interfacial surface.

In accordance with a preferred embodiment of the present invention, the rotational member has an aperture formed generally along the axis of rotation, such that a workpiece may pass therethrough.

Additionally in accordance with a preferred embodiment of the present invention, the aperture is adapted to allow passage therethrough of a cooling fluid towards the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated from the following detailed description, taken in conjunction with the drawings in which

Fig. 1 is a simplified sectional illustration of a prior art rotary valve, Fig 2 is a simplified sectional illustration of a rotary valve constructed and operative in accordance with a preferred embodiment ofthe present invention,

Fig 3 is a more detailed illustration of a portion of the rotary valve of Fig 2, and Fig 4 is a simplified pictorial illustration of a rotatable member of the rotary valve of Fig. 2

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will be appreciated by first referring to a typical prior art rotary valve 10, as illustrated in Fig 1 Prior art rotary valve 10 includes a stationary member 12 and a rotating member 14 Rotating member 14 is rotatably supported by bearings 15 mounted in stationary member 12

Stationary member 12 includes two inlet ports 16 and 18, each in fluid communication with a source of compressed air (not shown) via a solenoid valve 20 The purpose of solenoid valve 20, inter alia, is to switch the flow of pressurized air to either of inlet ports 16 and 18

Inlet port 16 is in fluid communication with a first longitudinal channel 22 formed in rotating member 14, via an orifice 24 Inlet port 18 is in fluid communication with a second longitudinal channel 26 formed in rotating member 14, via an orifice 28 Second longitudinal channel 26 is generally parallel with first longitudinal channel 22 and is separated therefrom by a thin wall 30 Thus an air flow 32 may flow through first longitudinal channel 22 via inlet port 16 or an air flow 34 may flow through second longitudinal channel 26 via inlet port 18, depending on the switching action of solenoid 20

An end 36 of rotating member 14 is fixedly attached by means of adaptors 37A and 37B to a spindle 38 which is rotatingly supported in a machine tool 40 by a bearing 42 The air flow 32 may, for example, be used to open the jaws of a chuck (not shown) of machine tool 40, while the air flow 34 may be used to close the jaws of the chuck

As discussed above, a disadvantage ofthe prior art rotary valve 10, is that only a relatively small diameter may be inserted through a central aperture 44 of rotating member 14 Reference is now made to Fig. 2 which illustrates a rotary valve 100 constructed and operative in accordance with a preferred embodiment of the present invention.

Rotary valve 100 includes a stationary member 102 and a rotatable member

104. Rotatable member 104 is rotatably supported by bearings 105 mounted in stationary member 102.

Stationary member 102 includes two passageways 106 and 108, each in fluid communication with a source of compressed air (not shown) via a pair of fluid connectors 1 10 and 1 12, respectively, and via a solenoid valve 1 14. The puφose of solenoid valve 1 14, inter alia, is to switch the flow of pressurized air to either of passageways 106 and 108. Passageways 106 and 108 have exit ports 120 and 122, respectively, formed on an interfacial surface 124. Part of passageway 108 and exit port 122 may be seen in greater detail in Fig. 3.

Rotatable member 104 has an axis of rotation 130 and a rotatable surface 132. It is a particular feature of the present invention that axis of rotation 130 is not parallel to and does not lie along interfacial surface 124 and rotatable surface 132. Preferably, as shown in Figs. 2 and 4, axis of rotation 130 is generally perpendicular to interfacial surface 124 and rotatable surface 132. Rotatable surface 132 has formed thereon two generally annular recesses 134 and 135, as seen in Fig. 4. Recesses 134 and 135 are in rotatable fluid communication with exit ports 120 and 122, respectively, of stationary member 102. Rotatable member 104 preferably has one or more receiving ports formed therein, such as receiving ports 140 and 142 shown in Fig. 2. As seen in Fig. 2, receiving ports 140 and 142 are in fluid communication with recesses 134 and 135, respectively, such that air may be conducted therethrough to operate a part, such as a chuck (not shown), of a machine tool 150. An end 152 of rotatable member 104 is fixedly attached, preferably by means of an adaptor 154 and one or more screws 155, to a spindle 156 which is rotatingly supported in machine tool 150 preferably by a bearing 158.

An air flow 160 may be conducted from solenoid valve 1 14 via connector 1 10, passageway 106, exit port 120 and receiving port 140, towards, for example, a chuck (not shown) of machine tool 150. The air flow 160 may, for example, be used to close the jaws of the chuck of machine tool 150.

An air flow 162 may flow from solenoid valve 1 14 via connector 1 12, passageway 108, exit port 122 and receiving port 142, towards, for example, the chuck of machine tool 150. The air flow 162 may, for example, be used to open the jaws of the chuck of machine tool 150.

It is a particular feature of the present invention, that compressed air flowing from exit ports 120 and 122 to recesses 134 and 135, respectively, imparts a force on interfacial surface 124 in the direction of an arrow 180, as shown in Fig. 3. The same compressed air imparts a reactive force on rotatable surface 132 in the direction of an arrow 182, as shown in Fig. 3. There is thus created a pressurized film of air 190 between interfacial surface 124 and rotatable surface 132 which provides lubrication between surfaces 124 and 132, thereby greatly reducing friction therebetween and allowing achieving high rotational speeds. In accordance with a preferred embodiment of the present invention, a control device, such as a nut ring 145, is provided for controlling the rotatable fluid communication between rotatable surface 132 and interfacial surface 124. For example, by tightening nut ring 145 against stationary member 102, the gap between surfaces 124 and 132 is reduced and air leakage from the gap is reduced. In accordance with a preferred embodiment of the present invention, rotatable member 104 has an aperture 170 formed generally along axis of rotation 130, as shown in Figs. 2 and 4. Unlike the prior art, a workpiece (not shown) of relatively large size or diameter may pass through aperture 170.

Additionally in accordance with a preferred embodiment of the present invention, aperture 170 may be adapted to allow passage therethrough of a cooling fluid (not shown) towards the workpiece (not shown). An adaptor 172 may be attached to rotatable member 104, as shown in Fig. 2. Adaptor 172 is preferably provided with a cooling fluid connector 174, supported by a bearing 176. for passage therethrough of the cooling fluid. The cooling fluid preferably flows through a recess 177 formed in adaptor 172, to an inlet port 179 formed in rotatable member 104. Inlet port 179 is at one end of a cooling fluid conduit (not seen in Fig. 2) formed in rotatable member 104. The cooling fluid conduit terminates at exit ports 178. The cooling fluid may flow from exit ports 178 towards the workpiece (not shown). It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope ofthe present invention is defined only by the claims that follow:

Claims

CLAIMS What is claimed is:

1. A rotary valve comprising: a stationary member comprising an interfacial surface; and a rotatable member attachable to a spindle of a machine tool, a portion of said machine tool being actuable by a working gas, said rotatable member having an axis of rotation and including a rotatable surface, said rotatable surface being in rotatable fluid communication with said interfacial surface of said stationary member, such that said working gas is conductable from said stationary member via said rotatable member to actuate said portion of said machine tool; wherein said working gas flowing from said interfacial surface to said rotatable surface imparts a pressure therebetween, thereby creating a lubricating film therebetween.

2. A rotary valve according to claim 1 and wherein said axis of rotation is not parallel to and does not lie along said interfacial surface and said rotatable surface.

3. A rotary valve according to claim 1 and wherein said axis of rotation is generally peφendicular to said interfacial surface and said rotatable surface.

4. A rotary valve according to any of claims 1 - 3 and comprising a control device for controlling the rotatable fluid communication between said rotatable surface and said interfacial surface.

5. A rotary valve according to claim 1 and wherein said rotational member has an aperture formed generally along said axis of rotation, such that a workpiece may pass therethrough.

6. A rotary valve according to claim 2 and wherein said rotational member has an aperture formed generally along said axis of rotation, such that a workpiece may pass therethrough.

7. A rotary valve according to claim 3 and wherein said rotational member has an aperture formed generally along said axis of rotation, such that a workpiece may pass therethrough.

8. A rotary valve according to any of claims 5 - 7 and wherein said aperture is adapted to allow passage therethrough of a cooling fluid towards said workpiece.