Movement device

Abstract

A device for moving an object relative to a surface, for example for pushing a bar in a bar feed mechanism, comprises a piston mounted for reciprocation within a chamber (2), and a piston rod (8) extending from one end of the chamber. Front and rear locking devices (12, 10) respectively associated with the piston rod (8) and chamber (2) are activated alternately in synchronism with the movement of the piston in opposite directions respectively in the chamber (2).

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a device for moving an object relative to a surface, for example, pushing, pulling, feeding, carrying, moving over or lifting an object.

BACKGROUND OF THE INVENTION

[0002] Bar feed machines are used to feed metal bars to machines in the engineering industry. In known bar feed machines, a bar is placed inside a length of tubular steel, which is the bar feed and is fixed to the turning machine. A small piston pusher is placed at the back of the bar feed and energy, such as pneumatic, hydraulic or electric, is transferred into the bar feed to force the pusher to move along the bar feed. The pusher in turn pushes the bar forward towards the turning machine where the metal is processed.

[0003] However, there are several disadvantages associated with such known bar feed mechanisms. Known mechanisms are expensive and pneumatic or hydraulic mechanisms in particular require the same amount of energy to be constantly fed into the bar feed. Thus, as the bar gets smaller and lighter it is pushed at a quicker rate against the turret of the turning machine. This can cause the turret to go off line.

[0004] Known pneumatic and hydraulic bar feeds are wasteful since the whole bar feed must be filled with air or oil. In addition, the distance through which the bar can be moved is limited by the inherent physical limitations on the movement of the hydraulic cylinder. The known systems are prone to wear and tear which can lead to leakage of air or oil which is wasteful and undesirable. Some of the known mechanisms are slow.

[0005] The present invention has been made from a consideration of the disadvantages associated with known feeding mechanisms and, in particular, in order to provide a movement device which overcomes one or more of those disadvantages.

SUMMARY OF THE INVENTION

[0006] According to the present invention there is provided a device for moving an object relative to a surface, the device comprising a piston mounted for reciprocation within a chamber, a piston rod extending from one end of the chamber, a first locking device associated with the chamber for locking the chamber relative to the surface, a second locking device associated with the piston rod for locking the piston rod relative to the surface, drive mean for effecting reciprocating movement of the piston in the chamber, and means for activating alternate locking devices in synchronism with the movement of the piston in opposite directions respectively in the chamber.

[0007] In connection with bar feed machines the device of the present invention avoids the constant energy requirement of known systems by only feeding the amount of energy required to move the bar forward at any given time. In addition, the device of the invention only requires energy to move the piston in the central chamber in order to move a bar forward. Thus, the device of the invention has a much lower energy requirement than the conventional hydraulic ram mechanism. The device is not as prone to wear and tear or leakage and the device has a fast response, for example it can be controlled to feed bars within microseconds of the chuck opening.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention will now be described further, by way of example only, with reference to the accompanying drawings, in which:

[0009] FIG. 1 is a side view of an embodiment of a device of the invention in the unextended, pressure-off configuration;

[0010] FIG. 2 is a side view of the device of FIG. 1 in the part-extended, pressure-on configuration;

[0011] FIG. 3 is a side view of the device of FIG. 1 in the fully extended, pressure-on configuration;

[0012] FIG. 4 is a side view of the device of FIG. 1 in the fully extended, pressure-off configuration;

[0013] FIG. 5 is a side view of the device of FIG. 1 in the part-extended, air exhaust configuration;

[0014] FIG. 6 is a view showing the internal components of the device of FIG. 1 in the pressure-on FIG. 4 configuration;

[0015] FIG. 7 is a view showing an example of a device of the invention in use;

[0016] FIG. 8 is a series of schematic views of alternative bore/bearing configurations suitable for use on a device of the invention;

[0017] FIG. 9 is a side view of an embodiment of the device of the invention adapted for pulling an object;

[0018] FIG. 10 is a side view of an embodiment of the device of the invention adapted for lifting an object; and

[0019] FIG. 11 is a schematic side view of a multi-jointed embodiment of a device of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Referring initially to FIGS. 1 and 6, the embodiment of device there shown is designed to move linearly along and within a bar feed tube 30 (FIG. 7) of circular cross-section, pushing a bar 42 ahead of it. The device comprises a relatively long tubular fluid-tight chamber 2 of circular cross-section having an external diameter slightly less than the inside diameter of the tube 30. The chamber 2 contains a piston 50 for reciprocating movement in the chamber. The piston 50 is fixed to a piston rod 8 which extends from one end of the chamber. A compression spring 56 within the chamber 2 biases the piston 50 towards the opposite end of the chamber.

[0021] A first, or rear, locking device 10 is fixed to the chamber 2 at the end opposite to that from which the piston rod 8 emerges. The locking device 10 comprises a housing 4 forming a second fluid-tight chamber which contains a frusto-conical piston 58. The housing 4 is much shorter than the main chamber 2 but has substantially the same external tubular dimensions as the chamber 2 and is coaxial therewith. The piston 58 is biased by a compression spring 90 towards the main chamber 2.

[0022] The housing 4 has side and rear ports 14, 16 respectively, either of which may be used to supply air (or other fluid) under pressure into the device. Each port communicates with a conduit 94 passing through an axial bore 92 in the piston 58, such that the fluid pressure is applied between the pistons 50 and 58 (O-rings 96 prevent the fluid pressure from being transmitted back through the gap between the bore 92 and conduit 94). Thus, when fluid pressure is applied to port 14 or 16 the piston 50 is driven in the chamber 2 towards the left (as seen in FIG. 6) against the bias of the spring 56, while the piston 58 is simultaneously driven towards the right in the housing 4 against the bias of the spring 90. When the fluid pressure is removed each piston 50, 58 returns to its initial position under the action of the spring 56 or 90.

[0023] The locking device 10 also comprises a plurality of ball bearings 21 equiangularly distributed around the axis of the piston rod 8, each captured in a respective aperture 19 in the housing 4 so that the ball bearings are constrained against axial movement relative to the housing 4 but can move radially relative to the axis of the piston rod 8. As seen, the ball bearings 21 are disposed around the frusto-conical surface of the piston 58.

[0024] A second, or front, locking device 12 is attached to the free end of the piston rod 8. This comprises a frusto-conical member 52, similar in shape to the piston 58, which is rigidly fixed to the free end of the piston rod. A housing 6 freely surrounds the member 52 and, like the housing 4, is much shorter than the main chamber 2 but has substantially the same external tubular dimensions as the main chamber 2 and is coaxial therewith. The piston rod 8 passes freely through the front wall of the housing 6 and a compression spring 54 biases the base of the housing 6 axially away from the member 52. A plurality of ball bearings 20 are equiangularly distributed around the axis of the piston rod 8, each captured in a respective aperture 18 in the housing 6 so that the ball bearings are constrained against axial movement relative to the housing 6 but can move radially relative to the axis of the piston rod 8. As seen, the ball bearings 20 are disposed around the frusto-conical surface of the member 52.

[0025] In operation, the device is inserted into one end of the tube 30, FIG. 7, in the unextended configuration shown in FIG. 1 (if the lateral port 14 is present the tube 30 will have a longitudinal slot to accommodate the port 14 as the device moves along the tube 30).

[0026] Now, fluid pressure is applied to the port 16 (or 14). This forces the piston 50 to the left (in the orientation shown in FIGS. 1 to 7) to extend the piston rod 8, and also forces the piston 58 to the right. Movement of the latter forces the ball bearings 21 radially outwards of the apertures 19 by the wedge action of the frusto-conical surface of the piston 58 on the ball bearings. This causes the ball bearings 21 to engage hard against the inside surface of the tube 30, thereby locking the housing 4 and chamber 2 against movement relative to the tube 30. Although the fluid pressure to move the piston 50 and activate the rear locking device 10 is applied at the same time, the rear locking device 10 will in practice lock first before the piston 50 starts to move.

[0027] With the device 10 locked, the piston rod 8 carrying the locking device 12 at its forward end moves forwardly in the tube 30, as indicated by the arrow in FIG. 2. The forward locking device 12 is not locked during such forward movement of the piston rod 8 because, during such movement (which is very rapid), the spring 54 is under greater compression than in a stationary state due to the inertia of the housing 6. Thus the ball bearings 20 are not forced into hard engagement with the interior of the tube 30 like the ball bearings 21.

[0028] After the piston rod 8 has reached its maximum stroke, FIG. 3, the fluid pressure is removed, FIG. 4. This deactivates the rear locking device 10 because the compression spring 90 returns the piston 58 to its initial position, releasing the ball bearings 21. However, removal of the fluid pressure activates the front locking device 12, for the following reason. The spring 56 rapidly attempts to withdraw the piston rod 8 onto the chamber 2. Due to the inertia of the housing 6, this causes the frusto-conical member 52 to move away from the base of the housing 6. Movement of the member 52 relative to the housing 6 thus forces the ball bearings 20 radially outwards of the apertures 18 by the wedge action of the frusto-conical surface of the member 52 on the ball bearings. This causes the ball bearings 20 to engage hard against the inside surface of the tube 30, thereby locking the housing 6 and piston rod 8 against movement relative to the tube 30. Thus, the chamber 2 is drawn forwardly along the now stationary piston rod 8, as shown by the arrow in FIG. 5.

[0029] At the end of the return piston stroke the device has returned to the FIG. 1 configuration but has moved along the tube 30 by the length of the stroke. Now, if the fluid pressure is re-applied the entire cycle as described occurs again and the device moves once more along the tube 30 by the length of the piston stroke. Therefore, by applying fluid pressure intermittently to the port 14 or 16, the device can be made to move intermittently along the tube 30, the locking devices 10 and 12 being activated alternately in synchronism with the reciprocating movement of the piston 50 in opposite directions respectively in the chamber 2. It will be observed, though, that activation of the forward locking device 12 is “passive”, in the sense that it occurs automatically due to movement of the member 52 relative to the housing 6 due to the inertia of the latter, whereas the activation of the rear locking device as positively effected by the application of fluid pressure. Effectively the forward locking device 12 is a passive device which allows one-way movement of the piston rod 8 relative to the tube 30.

[0030] FIG. 7 shows the application of a device of the invention to a bar feed machine. Referring to FIG. 7, the bar feed device is shown by the cut away detail A located within a bar tube 30. The device is controlled by a control unit 32 which includes a 24V solenoid 34, an oil reservoir 36, an air inlet 38 and an exhaust outlet 40. The control unit 32 is connected to the side entry port 14 or the back entry port 16 of the device. The control unit successively activates the device 1 so that the device proceeds forwardly along the tube 30 pushing feed bar 42 out the remote end of the tube. Each signal from the control unit may give, for example, approximately 25 mm of travel.

[0031] Sample programme operations of the device may be as follows:

[0032] Programme (1) to obtain a single travel distance movement:

[0033] Chuck open;

[0034] Feeder on with dwell if required;

[0035] Chuck close;

[0036] Feeder off.

[0037] Programme (2) to obtain a three times travel distance movement:

[0038] Chuck open;

[0039] Feeder on;

[0040] Feeder off;

[0041] Feeder on;

[0042] Feeder off;

[0043] Feeder on;

[0044] Chuck close;

[0045] Feeder off.

[0046] Referring to FIGS. 8, (a) to (d) show that the external cross-section of the device may be varied to accommodate tubes 30 of various internal cross-sections. Thus, for example, the device may be provided with a hexagonal, square, circular or triangular cross-section.

[0047] FIG. 8(e) shows an alternative arrangement wherein a device having two opposite halves 44 pivoted together can be secured with a clamp around the outside of a tube and the required grip is provided by bearings 46 protruding through apertures provided on the internal wall of the two halves. Again, the two halves of the device may have any cross-sectional shape. FIG. 8(f) is a cross-section of a device for movement across a flat surface wherein grip means 48 can protrude and retract through apertures provided linearly along an external surface of the device. It will be appreciated that any other suitable locking devices may be used.

[0048] Referring to FIG. 9, the device described above can be adapted for pulling an object by extending the piston rod 8 back through the rear of the rear housing 4. The device comprises a chamber 2 and housings 4, 6 as previously described. In addition, the device comprises a repositioned side port 60 and the piston rod 8 extends through the rear of the rear chamber 4 as extended rod portion 8′. Suitable pulling connections 62 are provided on a pulling support 64 which incorporates a rear port 66. In use, the object to be pulled is attached to the pulling connections 62 and the device is activated.

[0049] Referring to FIG. 10, the device described above can be adapted for lifting an object by extending the rod 8 forwardly through the front of the front housing 6, by means of an end button or the like. The device comprises a chamber 2 and housings 4, 6 as previously described. In addition, the device comprises an extension means or button 70 connected to the rod 8. The extension means, which is shown more clearly in FIG. 10(b), comprises a platform 72 supported by a shaft 74, a threaded portion 76 of which engages with a corresponding threaded aperture provided in the front end of the piston rod 8. In use, an object can be lifted upwardly by the platform 72.

[0050] As an alternative to fluid-pressure operated device the front and rear locking devices may be activated in any other suitable manner, for example by electromagnetic means. By suitable choice of the design of the device it can push, pull, lift or carry objects relative to a surface, by bodily moving itself intermittently along surfaces of various shapes.

[0051] The device has several advantages. The device can interface internally or externally with an object to move over its surface. When the device is powered, it is capable of moving itself forward at a rate and speed predetermined by the size of the shafts and frequency at which the device is powered. The device will push forward any objects that are placed in its path or will pull or carry objects that are connected to it.

[0052] It will be appreciated that the device of the invention can be used in a variety of applications other than as described with reference to bar feed machines. For example, the device could be used to unblock drains or could be used on the outside of a lamp post or the like. The device can crawl forward without being attached to an object and can travel unlimited distances. The device can move vertically or horizontally and is not confined to linear movement. For example, the device may be in the form of a curved device or a multi-jointed device which can go around a curve or bend or in any desired direction. An example of such a general arrangement is shown schematically in FIG. 11 wherein the device is defined by a series of interengaged tapered joints 80 which allow the device to negotiate bends and generally to move non-linearly.

[0053] The device may be made from any suitable material and may have any suitable shape and size for the desired application. It can be designed to travel specific distances, for example 10 mm, as required. The device is cost effective and easy to manufacture and requires little maintenance. If desired for a particular application, the device can be operated remotely. The device may be operated or activated by any suitable means, such as pneumatic, hydraulic or electronic means. The use of a side power port allows the power cable to be fed through a slot in the tube which avoids the use of a long cable on the back going up the tube in use.

[0054] The device can readily be made to travel in reverse by powering the device from the opposite end. For example, front ports may be provided to facilitate applying pressure to the front end, or both front and rear ports may be provided so that the device can be driven in either direction or me made to change direction as desired. It will be appreciated that the device can be self-powering. For example, a compressed air container or other power source may be incorporated into the device and a remote control unit may be used to activate the power source.

[0055] It will be appreciated that the present invention is not intended to be restricted to the details of the above embodiments which are described by way of example only.

Claims

1. A device for moving an object relative to a surface, the device being characterised by a piston (50) mounted for reciprocation within a chamber (2), a piston rod (8) extending from one end of the chamber, a first locking device (10) associated with the chamber for locking the chamber relative to the surface, a second locking device (12) associated with the piston rod for locking the piston rod relative to the surface, drive means (14, 56) for effecting reciprocating movement of the piston in the chamber, and means (52, 58) for activating alternate locking devices in synchronism with the movement of the piston in opposite directions respectively in the chamber.

2. A device as claimed in claim 1, wherein the drive means comprises means (14) for applying fluid pressure intermittently to the chamber (2) on one side of the piston (50), the fluid pressure forcing the piston along the chamber from an initial position, the drive means further including means (56) to return the piston to its initial position upon removal of the fluid pressure.

3. A device as claimed in claim 2, wherein the return means comprises a resilient biasing means (56).

4. A device as claimed in claim 1, 2 or 3, wherein the first locking device (10) comprises at least one locking element (21) which upon activation of the first locking device is forced laterally outwardly, relative to the axis of the piston rod (8), into engagement with the surface.

5. A device as claimed in claim 4 when directly or indirectly dependent on claim 2, wherein the at least one locking element (21) is forced laterally outwardly by the fluid pressure applied to the chamber (2).

6. A device as claimed in claim 5, wherein the at least one locking element (21) is forced laterally outwardly by at least one wedge member (58) which is moved against a resilient bias (90) by the fluid pressure.

7. A device as claimed in claim 6, wherein there are a plurality of locking elements (21) disposed around the axis of the piston rod (8), and wherein the wedge member (58) has a conical surface which is substantially coaxial with the axis of the piston rod, the wedge member being moved substantially along its own axis by the fluid pressure to force the locking elements (21) simultaneously laterally outwardly relative to the piston rod axis.

8. A device as claimed in claim 7, wherein the wedge member (58) is contained within a housing (4), and wherein the locking elements (21) are balls which are forced outwardly through respective apertures (19) in the wall of the housing.

9. A device as claimed in any preceding claim, wherein the second locking device (12) comprises at least one further locking element (20) which upon activation of the second locking device is forced laterally outwardly, relative to the axis of the piston rod (8), into engagement with the surface.

10. A device as claimed in claim 9, wherein the at least one further locking element (20) is forced laterally outwardly by at least one further wedge member (52) which is fixed to the piston rod (8).

11. A device as claimed in claim 10, wherein the further wedge member (52) is contained within a further housing (6) which is resiliently biased for movement relative to the further wedge member in a direction substantially parallel to the axis of the piston rod (8), wherein the at least one further locking element (20) is captured for axial movement with the further housing but is free to move laterally thereof, whereby movement of the further wedge member (52) relative to the further housing (6) under the influence of the resilient bias (54) forces the at least one further locking element laterally outwardly.

12. A device as claimed in claim 11, wherein there are a plurality of further locking elements (20) disposed around the axis of the piston rod, and wherein the further wedge member (52) has a conical surface which is substantially coaxial with the axis of the piston rod (8), the further housing (6) being resiliently biased substantially along the axis of the conical surface of the further wedge member.

13. A device as claimed in claim 12, wherein the further locking elements (20) are balls which are forced outwardly through respective apertures (18) in the wall of the further housing (6).