GB2294975A

GB2294975A - Valve Assemblies

Info

Publication number: GB2294975A
Application number: GB9421011A
Authority: GB
Inventors: Brian Arthur Julian Ellis
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-10-18
Filing date: 1994-10-18
Publication date: 1996-05-15
Anticipated expiration: 2014-10-18
Also published as: GB9421011D0; GB2294975B

Abstract

A valve assembly (10) is movable along a cylinder (14) by air presure in the cylinder for the controlled feeding of a bar (11) to a lathe. The valve assembly (10) comprises a valve body (12) defining a passageway (20) for a pressurised fluid and a valve head (30) capable of being open and closed. When the valve head is in the closed position, the pressurised fluid can apply a force to the valve assembly (10) to drive the assembly along the cylinder (14). When the valve head is open, the pressurised fluid is released. The valve head opens when it passes beyond the end of the cylinder or when the valve body (12) contacts a stop (44). <IMAGE>

Description

Improvements in or relating to valve assemblies This invention relates to controlled feeders for use particularly, but not exclusively, in the controlled feeding of an elongate bar from a lathe machine.

Computer numerical controlled (CNC) lathes require the use of a feeder to feed an elongate bar to the tools to work the bar. At present, the operator has to monitor the feeding of the bar to determine when the end has been reached. This is disadvantagequs.

It is an object of this invention to obviate and/or mitigate this disadvantage.

According to one aspect of this invention, there is provided a valve assembly movable along a cylinder for the controlled feeding of an article therealong, the valve assembly comprising a main body defining a passageway for a pressurised fluid, and release means capable of being opened and closed, whereby when the release means is closed, the pressurised fluid can apply a force to the valve assembly to drive the assembly along the cylinder and, when the release means is open, the pressurised fluid can be released to remove the force from the valve assembly.

In this specification, the word cylinder is intended to mean an elongate conduit along which the valve assembly can move. It will be appreciated that the cylinder can be of any suitable cross section, for example circular or square.

In a first embodiment of this invention, the release means comprises a valve head seatable against a valve seat defined in the passageway. Preferably, the valve head is movable between opened and closed positions. The passageway may extend substantially longitudinally of the valve body from an opening at a rear end of the valve body to an opening at the forward end of the valve body. Preferably, the valve seat tapers outwardly towards the forward end of the valve body.

Urging means may be provided to urge the valve head to the closed position. The urging means may comprise a spring, preferably a compression spring. The urging means may be mounted upon an elongate support connected to the valve head. The support may comprise a valve stem extending through the recess.

In the first embodiment, the valve head is frusto-conical in configuration and the valve seat is preferably of a corresponding configuration. Sealing means may be provided to seal the valve head against the valve seat when the release means is in the closed position. The sealing means may be in the form of an O-ring provided on the valve head.

The valve body may be so formed as to be sealed against the cylinder to prevent leakage of said pressurised fluid. Preferably, the valve body is formed of a suitable material to effect said sealing, for example, acetal. Alternatively, a sealing element may be provided, preferably in the form of a further O-ring seal.

In a second embodiment of the invention, the passageway extends from a rear end of the valve body to an aperture in the side wall of the valve body.

Preferably, sealing means are provided to seal the valve body against the cylinder thereby to prevent release of the pressursed fluid. Preferably, the pressursed fluid is released when said aperture reaches an opening in the cylinder. The second embodiment of valve assembly may further include a valve head suitable against a valve seat defined in the passageway. The second embodiment may include urging means to urge the valve head against the valve seat.

In the second embodiment, the urging means extends between the valve head and the closed end of the forward end of the valve body. In this embodiment, the valve head is provided to assist in the retrieval of the valve assembly after use. A valve stem may extend substantially longitudinally through the valve body upon which the valve head can ride. The valve head may be sealed against the valve seat by appropriate sealing means, for example, an O-ring seal.

Further sealing means may be provided at either side of the aperture to seal the valve body against the clyinder to prevent release of the pressurised fluid until said aperture reaches said opening in the cylinder.

According to another aspect of this invention, there is provided an arrangement for the controlled feeding of an article, the arrangement comprising a valve assembly as described in paragraphs 4 to 12 above and a cylinder means for supplying pressurised fluid to the cylinder to apply a force to the valve assembly and a means of detecting when the pressure applied to the cylinder has been released to prevent further supply of pressursed fluid.

According to a further aspect of the present invention there is provided a feed arrangement for the controlled feeding of an article, the arrangement comprising a valve assembly as described in paragraphs 4 to 12 above and a cylinder, means for moving the valve assembly in one direction in the cylinder whereby to feed said article along he cylinder, and release means capable of being opened and closed, whereby when the release means is closed, the pressurised fluid can apply a force to the valve assembly to drive the assembly along the cylinder and, when the release means is open, the pressurised fluid can be released to remove the force from the valve assembly.

The pressurised fluid supply may be compressed air from a suitable compressor source.

Preferably the controlled feeding of the article may be interrupted by the intervention of a collet acting on the said article such that only a discrete measure of the article is fed between interruptions.

The invention also provides a method for the controlled feeding of an article, in which the movement of a valve assembly driven along a cylinder in the first direction by a pressurised fluid feeds the article at a controlled rate through the cylinder, when the valve assembly reaches a predetermined location in the cylinder the valve assembly operates to release the pressurised fluid and prevent further movement of the article the release of pressurised fluid is detected by detecting means and further supply of pressurised fluid prevented.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figs. 1 and 2 are sectional views illustrating a first embodiment of the apparatus in different positions; Fig. 3 is a cross-sectional view of the first embodiment of the apparatus along line A-A; Figs. 4 and 5 are sectional views illustrating a second embodiment of the apparatus in different positions; and Figs. 6 and 7 are sectional side views illustrating a third embodiment in different positions.

In both embodiments, a valve assembly 10 is shown for the controlled feeding of an article such as an elongate bar 11 to a lathe machine, for example a computer numerical controlled (CNC) lathe machine. The valve assembly 10 comprises a valve body 12 slidably movable within a cylinder 14 of circular cross-section having first and second ends 46 and 48.

In a first embodiment of the apparatus as shown in Fig. 1, the valve body 12 is formed to effect a slidable seal between the valve body 12 and the cylinder 14. The valve body is formed of a suitable plastics material, for example acetal. If desired an 0-ring seal (not shown) can be located within an annular recess (not shown) in the peripheral surface of the valve body 12.

The valve body 12 has a through aperture 20 of circular cross-section opening onto respective end faces 22, 24 of the valve body 12. From the end face 22, the aperture 20 has a section 26 of constant diameter leading onto a section 28 which continuously increases in diameter towards the end face 24, thereby defining a frusto-conical recess.

A valve head 30 is provided in the section 28 and is of frusto-conical configuration to correspond with the shape of the section 28. Extending rearwardly from the valve head 30 there is provided a valve stem 32 terminating at an end portion 34 of greater diameter than the valve stem 32. The valve head 30 has a forwardly projecting portion 33 defining a substantially conical recess 35 to receive the end of the bar 11 and hold the bar 11 concentrically with the cylinder 14.

A compression spring 36 extends between the end portion 34 and an annular projection 38 extending inwardly of the section 26 within the valve body 12.

The spring 36 urges the valve head 30 against the section 28. The valve head 30 is seated against the section 28 by an 0-ring seal 40 mounted in a recess 42.

As can be seen from Figs. 1 and 2, there is provided an abutment 44 towards the second end 48 of the cylinder 14 defining a stop against which the valve assembly 10 can abut, as will be explained below.

Assembly 10 abuts the abutment 44, the valve body 12 is prevented from further movement, but the valve head 30 is capable of extending past the abutment 44.

An article, for example an elongated bar is inserted into the cylinder 14 so as to abut the end face 24 of the valve body 12. Air pressure is supplied to the first end 46 of the cylinder 14 and increased, e.g.

to 15 psi, so as to drive the valve assembly 10 along the cylinder 14 from the first end 46 towards the second end 48. The movement of the valve assembly 10 urges the elongate bar 11 along the cylinder 14 and to exit via the second end 48.

A collet 50 acting at the second end 48 periodically opens and closes to allow discrete lengths of the elongate bar 11 to be fed past the second end 48.

The collet 50 is controlled by the CNC lathe machine and is connected to the machine.

A supply 152 of compressed air is connected to the end 46 of the cylinder 14. The supply 152 is connected to a gauge 154 to measure the pressure inside the cylinder and sensing means in the form of a pressure switch 156 to switch off the supply of compressed air and the CNC lathe machine when the pressure descends below a predetermined threshold (see below).

In operation, the bar 11 is fed into the cylinder 14 via the second end 48 and the collet 50, the valve assembly 10 being arranged at the first end 46 of the cylinder 14. The bar 11 is pushed into the cylinder 14 until the bar 11 engages the forwarding extending portion 33 of the valve head 30 in the recess 35.

The supply 152 of compressed air is then switched on to apply a force to the valve assembly 10 and the bar 11 along the cylinder 14 in the direction of the arrow B (see Fig. 1). The supply of compressed air pressurises the cylinder to, for example, 15 psi which can be read on the gauge 154. Suitable guide means (not shown) engages the forward free end of the bar 11 and, when the collet 50 opens the guide means moves away from the collet 50 in the direction of the arrow B to allow the bar 11 to be pushed by the valve assembly 10 in the direction of the arrow B until a desired length of the bar 11 extends from the collet 50. The collet 50 then closes to hold the bar in position to allow the lathe to work the protruding end portion of the bar 11 in a known manner. When the working is completed, the above steps are then repeated.

Thus, the valve assembly 10 moves forward in the direction of the arrow B.

When the valve assembly 10 abuts the abutment 44, the valve body 12 is prevented from further movement, the collet opens, this action allows the valve head 30 to extend past the abutment 44 and thereby to release the air pressure within the cylinder 14.

The pressure switch 156 detects the decrease in pressure within the cylinder 14 and switches the air pressure supply off when the pressure falls below a predetermined threshold, e.g. 5 psi. When the air pressure ceases to act on the valve body 12 the valve head 30 returns to a closed position under the influence of the spring 36.

A user of the apparatus can remove the remainder of the elongated bar from the second end 48 of the cylinder 14, and can activate the supply 52 in reverse so that the valve assembly 10 is sucked back along the cylinder 14 to the first end 46, so the above described action may be repeated.

Like references have been used to indicate identical parts in all Figs.

In a second embodiment of the apparatus as shown in Figs 4 and 5, a slidable seal is effected between the valve body 12 and the cylinder 14 by means of 0-rings seals 52 located within annular recesses 54 in the peripheral surface of the valve body 12. The latter has as chamber 56 of circular cross-section with first and second ends 76 and 78. The first end 76 has an opening aperture 58 extending between the chamber 56 and a first end face 60 of the valve body 12. From the first end face 60 the opening aperture 58 has a section 62 of constant diameter leading into a section 64 which continously increases in diameter to that of the diameter of the chamber 56, thereby defining a frusto-conical recess.

A valve 66 is provided in the section 64 and is of frusto-conical configuration to correspond with the shape of the section 64. Extending through the valve head 66 from a first end face 68 to a second end face 70 is an aperture to allow the valve head 66 to slide on a valve stem 72 between open and closed positions.

The valve stem 72 extends along the longitudinal axis of the valve body 12 such that a first end having a larger diameter is retained within section 62 of the opening aperture 58 and the second end is attached to the second end 78 of the chamber 56.

A compression spring 74 extends between the second end 78 of the chamber 56 and an annular recess 80 formed in the second end face 70 of the valve head 66. The spring 74 urges the valve head 66 against section 64.

The valve head 30 is seated against section 64 by an 0ring seal 82 mounted in a recess 84. An air exhaust aperture 86 extends through the valve body 12 into the chamber 56.

An elongate bar 11 is inserted into the cylinder 14 so as to abut the recess 35 of the forwardly extending portion 33 of the valve body 12. Air pressure is supplied to the first end 46 of the cylinder 14 by the supply 152 of compressed air to 15 psi, so as to drive the valve assembly 10 along the cylinder 14 from the first end 46 towards the second end 48. The movement of the valve assembly 10 urges the elongate bar 11 along the cylinder 14 to exit via the second end 48.

The operation of the lathe machine in controlling movement of the bar 11 the same as that described with reference to Figs. 1 to 3 with the exception that the guide means (not shown) may allow the bar to move forward a distance greater than required and then push the bar 11 back into the cylinder 14 to the required position.

The collet 50 acting on the second end 48 periodically opens and closes to allow discrete lengths of the elongated bar to feed past the second end 48.

When the valve assembly 10 reaches the end 48 of the cylinder 14 such that the 0-ring seal 54 is pushed past the end 48, the pressursed air in the chamber 56 in the valve body 12 escapes via the air exhaust aperture 86.

The pressure switch 156 detects the decrease in pressure and switches off the pressurised air supply and the CNC lathe machine when the pressure falls below a predetermined threshold, e.g. 5 psi. When the air pressure ceases to act on the valve body 12 the valve head 66 returns to the closed position under the influence of the spring 72. The user of the apparatus can remove the remainder of the elongated bar from the second end 48 of the cylinder 14, and can activate a suction supply at the first end 46 so that the valve assembly 10 is sucked back along the cylinder 14 to a first end 46, so that the above described action may be repeated.

Figs. 6 and 7 show an alternative embodiment to that shown in Figs. 4 and 5 which is generally the same as that shown in Figs. 4 and 5 with the exception that the cylinder 14 is provided with an air release aperture 88, whereby when valve assembly 10 is pushed down the cylinder 14 such that the 0-ring seal 54 is moved past the aperture 58, the air in the chamber 56 is released via the air exhaust aperture 86 in the valve body 12 and the air release aperture 88 in the cylinder 14. The release of pressure causes a drop in the pressure in the cylinder 14 resulting in the pressure switch 156 switching off the supply 152 of compressed air and the CNC lathe machine in the same way as described above.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A valve assembly movable along a cylinder for the controlled feeding of an article therealong, the valve assembly comprising a valve body defining a passageway for a pressurised fluid, and release means capable of being opened and closed, whereby when the release means is closed, the pressurised fluid can apply a force to the valve assembly to drive the assembly along the cylinder and, when the release means is open, the pressurised fluid can be released.

2. A valve assembly according to Claim 1 wherein the release means comprises a valve head seatable against a valve seat defined in the passageway.

3. A valve assembly according to Claim 2 wherein the valve head is movable between opened and closed positions.

4. A valve assembly according to Claim 2 or 3 wherein the valve head is frusto-conical in configuration and the valve seat is of a corresponding configuration.

5. A valve assembly according to Claim 2,3 or 4 wherein sealing means is provided to seal the valve head against the valve seat when the release means is in the closed position.

6. A valve assembly according to Claim 5 wherein the sealing means may be in the form of an 0-ring provided on the valve head.

7. A valve assembly according to any preceding claim wherein the passageway extends substantially longitudinally of the valve body from an opening at a rear end of the valve body to an opening at the forward end of the valve body.

8. A valve assembly according to any preceding claim wherein the valve seat tapers outwardly towards the forward end of the valve body.

9. A valve assembly according to any preceding claim further including urging means to urge the valve head to the closed position.

10. A valve assembly according to Claim 9 wherein the urging means comprises a spring.

11. A valve assembly according to Claim 9 or 10 wherein the urging means is mounted upon an elongate support connected to the release means.

12. A valve assembly according to Claim 11 wherein the support comprises a valve stem extending through the recess.

13. A valve assembly according to any preceding claim wherein the valve body is so formed as to be sealed against the cylinder to prevent leakage of said pressurised fluid.

14. A valve assembly according to Claim 13 wherein the valve body is formed of a suitable material to effect said sealing.

15. A valve assembly according to Claim 14 wherein the valve body is formed of acetal.

16. A valve assembly according to Claim 13 wherein a sealing element is provided to effect said seal between the valve body and the cylinder.

17. A valve assembly according to Claim 1 wherein the passageway extends from a rear end of the valve body to an aperture in the side wall of the valve body.

18. A valve assembly according to Claim 17 wherein sealing means are provided to seal the valve body against the cylinder thereby to prevent release of the pressurised fluid.

19. A valve assembly according to Claim 18 wherein the pressurised fluid is released when said aperture reaches an opening in the cylinder.

20. A valve assembly according to any of Claims 17 to 19 further including a valve head seatable against a valve seat defined in the passageway.

21. A valve assembly according to Claim 20 further including urging means to urge the valve head against the valve seat.

22. A valve assembly according to Claim 21 wherein the urging means extends between the valve head and the closed end of the forward end of the valve body.

23. A valve assembly according to Claim 20, 21 or 22 further including a valve stem extending substantially longitudinally through the valve body upon which the valve head can ride.

24. A valve assembly according to any of Claims 21 to 23 wherein the valve head is sealed against the valve seat by an appropriate sealing element.

25. A valve assembly according to any of Claims 17 to 24 including further sealing means at either side of the aperture to seal the valve body against the cylinder to prevent release of the pressurised fluid until said aperture reaches said opening in the cylinder.

26. An arrangement for the controlled feeding of an article, the arrangement comprising a valve assembly as claimed in any of Claims 1 to 25, a cylinder along which the valve assembly can move, means for supplying pressurised fluid to the cylinder to apply a force to the valve asembly and a means of detecting when the pressure applied to the cylinder has been released to prevent further supply of pressurised fluid.

27. An arrangement according to Claim 26 wherein the detecting means comprises a pressure gauge to detect a drop in pressure in said cylinder when said pressure has been released.

28. A feed arrangement for the controlled feeding of an article, the arrangement comprising a valve assembly as claimed in Claims 1 to 25, a cylinder along which the valve assembly can move, means for moving the valve assembly in one direction along the cylinder whereby to feed said article along the cylinder, and release means capable of being opened and closed, whereby when the release means is closed, the pressurised fluid can apply a force to the valve assembly to drive the assembly along the cylinder and, when the release means is open, the pressurised fluid can be released.

29. A feed arrangement according to Claim 28 wherein the pressurised fluid supply is compressed air from a suitable compressor source.

30. A feed arrangement according to Claim 28 or 29 wherein the controlled feeding of the article can be interrupted by the intervention of a collet acting on the said article such that only a discrete measure of the article is fed between interruptions.

31. A method for the controlled feeding of an article, in which the movement of a valve assembly driven along a cylinder in the first direction by a pressurised fluid feeds the article at a controlled rate through the cylinder, when the valve assembly reaches a predetermined location in the cylinder the valve assembly operates to release the pressurised fluid and prevent further movement of the article the release of pressurised fluid is detected by detecting means and further supply of pressurised fluid prevented.

32. A valve assembly substantially as herein described with reference to and as shown in the accompanying drawings.

33. An arrangement for the controlled feeding of an article substantially as herein described with reference to and as shown in the accompanying drawings.

34. A method for the controlled feeding of an article substantially as herein described with reference to and as shown in the accompanying drawings.

35. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.