GB2254580A

GB2254580A - Cutting element

Info

Publication number: GB2254580A
Application number: GB9206297A
Authority: GB
Inventors: Ernest Holland; Peter Simpson Kirkwoo Grossart
Original assignee: VL Churchill Ltd
Current assignee: VL Churchill Ltd
Priority date: 1991-03-23
Filing date: 1992-03-23
Publication date: 1992-10-14
Also published as: GB9106222D0; GB9206297D0

Abstract

A cutting and spreading implement comprises a pair of arms 10 and 11 pivoted at 12 and capable of being moved towards and away from each other by a pivot linkage 31, 32 attached to hydraulic ram means, 33, 34. The piston 37 of the hydraulic drive is double acting under the control of a spool valve 50 operated by ballbearing elements 49 and a manually rotatable cam sleeve 48. The arms have replaceable cutting elements 15 each having a central projecting discontinuity 17 to grip and cut. The arms 10 and 11 have removable spreader tips 19, 20 having serrated outer edges 24 adapted to prise apart members on separation of the arms. The implement is used for rescue and salvage purposes. <IMAGE>

Description

CUTTING IMPLEMENT This invention relates to a cutting implement and in particular to a high powered cutting implement suitable for heavy duty purposes in, for example, the cutting up of vehicles damaged in collisions.

Cutting implements have hitherto comprised a pair of arms pivoted to be brought together by power operated means and having cutting edges along their inside edges. Similar devices have been provided for prising apart a small opening, the tips of the arms being inserted into the opening and the arms being moved apart to widen the opening. In some cases the cutting and prising apart functions have been combined in a single device.

It is an object of the invention to provide a new or improved cutting apparatus.

According to the invention there is provided a cutting implement comprising a pair of arms pivotally mounted at pivot means, drive means connected to the arms to cause the arms to pivot relative to the pivot means, each arm having a cutting element on its edge facing the other arm, the cutting elements being adapted to overlap scissor fashion when the arms are pivoted towards each other, wherein the cutting elements are removable and replaceable.

Each cutting element may have a discontinuity in its cutting edge, the two discontinuities being disposed to cooperate with each other.

Each discontinuity may comprise a projection which may be pointed or a notch, or a combination of one or more projections and notches.

The discontinuities may be spaced from the pivot means and from the free ends of the arms.

The cutting implement may advantageously be a combination cutting and spreading implement.

To this end, each arm may be provided with a narrow spreader tip whereby, when the arms are pivoted together the tips may be inserted in an aperture and, when the arms are pivoted apart the spreader elements force apart the sides of the aperture.

Preferably, each spreader tip is provided on a spreader element which is removable and replaceable from the arm.

Each spreader tip may be provided with outer and/or inner serrated edges.

The drive means for the arm may comprise a fluid operated piston and cylinder assembly.

The piston and cylinder assembly may be pivotally attached to a pair of links, each link being pivotally attached to a respective arm at a pivot point spaced from said pivot means.

The piston and cylinder assembly may be hydraulic. It may be double acting for powered opening and closing of the pivoted arms.

The double acting piston and cylinder assembly may be controlled by reversing valve means comprising a linear spool valve moveable between two extreme positions by a pair of ballbearing elements engaged by manually operated rotary cam means.

Further features of the invention will appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings, in which: Fig. 1 shows a plan view of a cutting implement with part in section, and Fig. 2 shows an end view on the line 2-2 in Fig. 1.

Referring to the drawings a cutting implement is illustrated which can also serve to prise apart or spread two adjacent members. The illustrated implement is particularly intended for cutting up and bending parts of vehicles during rescue operations to free persons trapped in the vehicles following collisions, but the implement can have other applications.

For this purpose the implement should be relatively lightweight and compact whilst being able to undertake heavy duty cutting and spreading operations. Moreover the implement should be capable of operating in arduous conditions and be easily maintained should it become damaged.

The implement includes a pair of arms 10 and 11 which are pivoted together about an axis 12, the arms being driven by drive means 13. One of the arms 11 is shown in its closed position 11' in addition to its open position 11.

Each of the arms 10 and 11 provides a seating 14 for a replaceable cutting element 15 arranged so that, during a cutting operation, the cutting edges of the cutting elements 15 are able to overlap in the manner of scissors. Along each of the cutting edges of the cutting elements 15 is formed a discontinuity 17 comprising a pointed projection integral with the element 15.

The elements 15 are releasably carried on the arms 10 and 11 by fixing means 18 such that should the members 15 become blunted or damaged they may be easily replaced. They may be made of different material than the arms, and as hardened steel or may be coated for example to reduce friction or increase wear resistance.

At the outer ends of the arms 10 and 11 are located spreader elements 19 and 20, each having a boss 22 located in a recess in the ends of the arms and being releasably secured by a spring biased location member 21. The spreader elements 19 and 20 are of generally tapered form converging to a tip or point 23 located along the line of the leading edge of the associated arm. Serrations are formed on the outer and inner edges of the spreader elements as at 24 and 25.

The arrangement of the spreader elements 19 and 20 is such that the tips 23 can, when the arms are brought together, be inserted into a small opening. Then when the arms are driven apart the opening is enlarged or prized apart. As the opening is enlarged the elements 19 and 20 are inserted further into the opening and the notched portions 24, 25 serve to give further purchase on the materials being engaged.

The arm 11' is shown with the spreader element 20 and the cutting element 15 removed. It will be seen that the cutting element protrudes laterally beyond the inner edge of the associated arm and the arm protrudes radially outward of the outer edge of the cutting element 15.

Each of the arms 10 and 11 carries adjacent the pivot 12 but to the opposite side of the pivot 12 from the cutting elements 15, locations 30 for securing a pair of links 31 and 32, one for each of the arms 10 and 11. The opposite ends of the links are pivotally connected to a piston rod assembly 33 at 34.

The piston rod assembly 33 is movable reciprocally of a combined handle and housing 35 and includes a piston rod 36 on which is carried a piston 37. The piston 37 and piston rod 36 are double acting and located within a cylinder 38 of the housing 35. Operating fluid is supplied to the piston and cylinder device to opposite sides of the piston 37 through a fluid inlet 39 to one side of the piston and through a bore 40 in the piston rod and to an outlet 41 to the opposite side of the piston 37.

Supply of hydraulic fluid to one or other side of the piston is controlled by a spool valve arrangement 43. The valve 43 is supplied with high pressure hydraulic fluid from an external source through a hose 45. The spool 50 of the valve 43 can be actuated to admit fluid to outlet 39 or 41 by a rotary movement of a cam 47 (Fig. 2). The cam 47 is arranged as part of a knurled sleeve 48 which, upon rotation about its longitudinal axis, causes actuating ball bearings 49 to move radially in and out under the action of the cam surface 47 thereby moving the spool 50 to its extreme positions so as respectively to open and close selected fluid passages.

This arrangement provides for a quick and simple means by which the arms 10 and 11 may be opened and closed in response to the operator's requirements, the operator twisting the sleeve 48 according to the direction of operation called for.

The operating load is low compared with that of a rotary valve.

The implement described can be readily adapted for cutting operations only by removal of the spreader elements 19 and 20.

This may make it easier to achieve continuous cutting since the tips cannot meet and limit shearing effects. Moreover if the spreader elements are employed but sustain some damage they may be quickly replaced. Similarly the cutting elements 15 are readily replaced if damaged and the provision of the projections 17 ensures that during cutting the element being cut is secured by the projections 17 during a cutting operation.

The implement has a guard/handle 52 by which the implement is positioned and manipulated.

Claims

1. A cutting implement comprising a pair of arms pivotally mounted at pivot means, drive means connected to the arms to cause the arms to pivot relative to the pivot means, each arm having a cutting element on its edge facing the other arm, the cutting elements being adapted to overlap scissor fashion when the arms are pivoted towards each other, wherein the cutting elements are removable and replaceable.

2. An implement according to claim 1 wherein each cutting element has a discontinuity in its cutting edge, the two discontinuities being disposed to cooperate with each other.

3. An implement according to claim 2 wherein each discontinuity comprises a projection.

4. An implement according to claim 3 wherein each projection is pointed.

5. An implement according to claim 2 wherein each discontinuity comprises a notch.

6. An implement according to any one claims 2-5 wherein the discontinuity comprises a combination of one or more projections and notches.

7. An implement according to any one of claims 3-6 wherein the discontinuities are spaced from the pivot means and from the free ends of the arms.

8. An implement according to any preceding claim comprising a cutting and spreading element.

9. An implement according to claim 8 wherein each arm is provided with a narrow spreader tip whereby, when the arms are pivoted together the tips may be inserted in an aperture and, when the arms are pivoted apart the spreader elements force apart the sides of the aperture.

10. An implement according to claim 9 wherein each spreader tip is provided on a spreader element which is removable and replaceable from the arm.

11. An implement according to claim 9 or claim 10 wherein each spreader tip is provided with outer and/or inner serrated edges.

12. An implement according to any preceding claim wherein the drive means comprise a fluid operated piston and cylinder assembly.

13. An implement according to claim 12 wherein the piston and cylinder assembly is pivotally attached to a pair of links, each link being pivotally attached to a respective arm at a pivot point spaced from said pivot means.

14. An implement according to claim 12 or claim 13 wherein said fluid operated piston and cylinder assembly is hydraulic.

15. An implement according to any one of claims 12-14 wherein the piston and cylinder assembly is double acting.

16. An implement according to claim 15 wherein the double acting piston and cylinder assembly is controlled by reversing valve means comprising a linear spool valve moveable between two extreme positions by a pair of ballbearing elements engaged by a manually operated rotary cam means.

17. A cutting implement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.