GB2330097A

GB2330097A - Tool mount

Info

Publication number: GB2330097A
Application number: GB9721134A
Authority: GB
Inventors: Paul Chalfont Fryer; Richard Paul Fryer; Jeremy Edward Fryer
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-10-07
Filing date: 1997-10-07
Publication date: 1999-04-14
Also published as: GB9721134D0

Abstract

A tool 20 for machining a work piece 30 is mounted on automated machinery 50 using a multi-part sleeve 52. The parts 54, 56 of the sleeve 52 are ordinarily coupled together, but the parts are separable if a sheer or bending force is generated in the sleeve 52. Thus, if movement of the machinery 50 in the direction of the arrow results in the tool 20 colliding with step 28 in the work piece 30, the parts 54,56 de-couple, exposing cabling 58 which controls the tool 20. The de-coupling enables the positioning of the tool 20 to change, reducing the risk of damage to the tool, and the cabling 58 prevents the tool 20 dropping onto the work piece 30. Once the step 28 is removed, the parts 54,56 are coupled back together to enable further machining of the work piece. Preferably, the tool mount further comprises sensing means (100, figure 5B) to sense whether the parts 54,56 are coupled together, each part 54,56 including electrical contacts which are connected when the parts 54,56 are coupled together, and disconnected when the parts 54,56 are separated. The sensing means may then provide a warning signal to the operator or may automatically shut down the power to the tool 20. The parts 54,56 are preferably coupled together using interfitting profiles, which may be a snap-fit mechanism (figures 5A to 9B). Alternatively or additionally, the coupling between the parts 54,56 may be biassed by a resilient member (90, figures 8A,B; or 96, figure 10) urging the parts together. Alternatively, the coupling between the parts 54,56 may comprise magnetic or adhesive means.

Description

TITLE : TOOL MOUNT The present invention relates to means for mounting a tool on to a support, particularly but not exclusively where the tool is of relatively high value and is readily damaged by coming into contact with a work piece.

Tools used for cutting, joining or marking of material are widely used in combination with automated machinery.

In the thermal cutting industry, for example, a plasma arc torch is typically used in combination with XY translating equipment 22 or a five axis industrial robot 24 as shown in figures 1 and 2 respectively. The plasma torch 20 is mounted on the machinery using a non-conductive rigid sleeve which both positions the torch and insulates the machinery from the high voltages and currents delivered to the torch. (The insulating properties of the sleeve are not required when welding or using adhesive applicators; in such applications electrically conductive materials are often used). However, during operation, it is not uncommon for the torch to come into contact accidentally with the work piece. Such "collisions" might occur through operator error, machine error, incorrect positioning of the work piece or unforseen movement of the work piece during operation.

Collision incidents risk damage to the torch, and sometimes result in fracture of the sleeve attaching the torch to supporting machinery. Commonly, the sleeve is somewhat sacrificial, being designed to fracture rather than allow the costly torch to be damaged. Sleeve fracture is illustrated schematically in figure 3. The torch 20 is mounted in sleeve 26 which is supported by machinery (22,24). Movement of the machinery in the direction of the arrow results in the torch 20 colliding with step 28 which may have been produced by an earlier cut made in the work piece 30. The movement of the torch 20 (but not the machinery) is arrested by the step 28, inducing sheer forces or bending movements in the sleeve which result in the breakage 32.

An object of the present invention is to reduce the risk of tool collision damage. Another object of the present invention is to reduce the down time associated with replacing a part or parts damaged during collision of the tool with the work piece.

In accordance with the present invention, there is provided means for mounting a tool on a support, comprising at least two parts which, in use, are releasably coupled together, the coupling between adjacent parts being such that the parts are separable by a force (eg shear or bending moment) induced between the parts by lateral movement of the tool relative to the support.

By definition, the coupling between the two parts has to be strong enough to withstand forces generated simply by the weight of the mounted tool. However, the two parts are designed to separate without breaking as soon as the induced force therebetween rises above a threshold value which is indicative of the tool colliding with an obstruction. De-coupling of the parts enables at least a portion of the impact of the collision to be absorbed by the mounting means and allows the tools to swing clear of the obstruction and out of harms way. Once the obstruction is removed, the parts may be coupled back together, allowing resumption of tool use.

The parts may have interfitting profiles, with the profile of one part fitting inside the profile of the other when the parts are coupled together. For example, the profiles may have corresponding step-like configurations.

The interfitting profiles assist in registering the parts in order to couple them together by providing a positive locating action.

The profiles may have interengaging portions for coupling the parts together. For example, the interengaging portions may screw together by mating threadings or have other releasable interfitting profiles, say of bayonet type. Preferably, the interengaging portions engage with a snap-fitting action, rather than a mere friction-fitting action. Such profiles advantageously provide a locating and coupling action.

The parts may be releasably coupled together with the aid of magnetic means or adhesive which has low strength or has limited substrate adhesion.

In a highly specialised embodiment, one of the interfitting profiles may straddle the other in order to provide a substantially waterproof coupling. The two parts of the mounting means may form a sleeve for encasing cabling used to control the tool. If water is used during tool operation, for example to cool the work piece, it is clearly desirable to prevent the ingress of water through the coupling to avoid contact with any cabling.

The coupling between the parts may be biased by a resilient member urging the parts together. The resilient member, eg a spring, may also provide a force urging the parts back into registration once they have been separated by the force induced by collision etc.

The mounting means may further comprise means for sensing whether or not the parts are coupled together. The operation of the tool may be controlled in dependence on signals received from the sensing means. For example, as soon as the sensing means senses that the parts have been decoupled, power to the tool may be interrupted until the parts are recoupled. The sensing means may comprise an electrical circuit breaker which is activated as the two parts separate.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows one kind of automated machinery commonly used in combination with cutting tools and the like; Figure 2 shows another kind of automated machinery commonly used in combination with cutting tools and the like; Figure 3 illustrates a problem of mounting tools on automated machinery; Figure 4 illustrates a tool mounted using a sleeve embodying the present invention; Figures 5a and b show coupling detail of parts of the sleeve of figure 4; Figures 6a and b show different coupling detail to that shown in figure 5; Figures 7a and b show different coupling to that shown in figures 5 and 6; Figures 8a and b show different coupling detail to that shown in figures 5, 6 and 7; Figures 9a and b show different coupling detail to that shown in figures 5 to 8; Figure 10 shows in cross section sleeve parts coupled together in yet another way; and Figure 11 shows an end view of the sleeve of figure 10; Figure 4 shows a tool 20 mounted on automated machinery 50 by multi-part sleeve 52. Movement of the machinery 50 in the direction of the arrow has resulted in the tool colliding with step 28 in the work piece 30 being machined. The impact of the collision generates a shear or bending force in the sleeve 52; a force which is not parallel to the longitudinal axis of the sleeve. The force has caused parts 54, 56 of the sleeve 52 to de-couple, exposing cabling 58 which controls the tool 20. The decoupling enables the position of the tool 20 to change, reducing the risk of tool 20 damage; the cabling 58 prevents the tool 20 dropping onto the workpiece 30. Once the step 28 is removed, the parts 54, 56 are coupled back together to enable further machine operation.

The parts 54, 56 of sleeve 52 in the case of a plasma arc torch mounting are comprised of resilient insulating material such as Delrin o or PEEK. The parts 54, 56 are cylindrical and opposing surfaces 60, 62 are provided with interfitting profiles, respectively. In figures 5a and b, part 54 has a tapered recess 64 which is a snug or interference fit around the dovetailed flange 66. In figures 6a and b, parts 54 and 56 both have tapered recesses 64 into which the dovetailed flanges 72, 74 of insert 70 are a tight or spring fit. The arrangement of figures 7a and b is the reverse of figures 6a and b; the parts 54 and 56 have dove-tailed flanges 76, 78 which are a spring fit in the recess 82 of collar 80.

In the arrangement of figures 8a and b, the flange 84 of part 54 is provided with a circumferential groove 86.

The corresponding recess 88 of part 56 is provided with a spring clip 90 which is a spring fit in the groove 86 when the parts are coupled together.

In the arrangement of figures 9a and 9b, the flange 92 of part 54 fits into a recess 94 within the part 56. The neck of recess 94 is slightly narrower than the leading edge of flange 92, so once past the neck, the flange 92 is firmly held in recess 94. The sides of the recess 94 create a mini-well, effecting a seal which resists the ingress of water.

Each of the arrangements of figures 5 to 9 illustrate parts which may be said to have a snap-fitting, coupling action. Figures 10 and 11 illustrate a form of coupling where no such snap-fit action is present. A sleeve 52 consists of six parts, two of which are numbered 54 and 56.

(In itself, figure 10 shows that more than two parts may be releasably coupled together, a fact applicable to all the embodiments of the present invention) . The opposing surfaces of parts 54, 56 have corresponding stepped profiles, enabling the profile of part 54 to be nested or located inside that of part 56. A pair of springs 96, extending parallel to the central axis of the sleeve 52, are attached to the end parts of the sleeve 52. The springs 96 are in tension and provide a bias urging all the parts, including parts 54 and 56, together. Adjacent parts may be separated by stretching the springs 96.

As shown schematically in figure 5b, an electrical circuit breaker may be integrally formed in the parts 54, 56. Electrical contacts in the profiles of the parts 54, 56 are automatically connected when the parts are coupled together. As soon as the parts 54, 56 separate, the electrical contact is broken and is sensed by sensor 100.

The operation of the tool could be made dependant upon the sensor 100 indicating that the parts are coupled together.

Alternatively, the sensor 100 may be connected to an alarm, visual or otherwise, to alert the operator to whether or not the parts 54, 56 are coupled together.

Claims

CLAIMS 1. Means for mounting a tool on a support, comprising at least two parts which, in use, are releasably coupled together, the coupling between adjacent parts being such that the parts are separable by a force induced between the parts by movement of the tool relative to the support.
2. Mounting means according to claim 1, in which the parts have interfitting profiles, with the profile of one part fitting inside the profile of the other when the parts are coupled together.
3. Mounting means according to claim 2, in which the profiles have interengaging formations for coupling the parts together.
4. Mounting means according to claim 3, in which the interengaging formations engage with a snap-fit action.
5. Mounting means according to any one of the proceeding claims, in which the coupling between the parts is biased by a resilient member urging the parts together.
6. Mounting means according to any one of the preceding claims, further comprising means for sensing whether or not the parts are coupled together.
7. Mounting means according to claim 6, in which the sensing means comprises electrical contacts which are connected when the parts are coupled together and disconnected when the parts are separated.
8. Mounting means according to any of the proceeding claims, in which the coupling between adjacent parts comprises magnetic or adhesive bonding means.
9. Mounting means according to any of the preceding claims, further comprising means linking at least two parts together which limits their maximum separation.
10. Apparatus for machining a workpiece, comprising a tool mounted by mounting means according to any of claims 1-9.
11. Means for mounting a tool on a support substantially as hereinbefore described, and as illustrated, with reference to figure 4 and any of figures 5, 6, 7, 8, 9 or 10 and 11.