GB2239831A

GB2239831A - Cutting blade and device

Info

Publication number: GB2239831A
Application number: GB9013071A
Authority: GB
Inventors: Arthur John Harbach
Original assignee: BURNTSTONE CERAMIC Ltd
Current assignee: BURNTSTONE CERAMIC Ltd
Priority date: 1989-06-13
Filing date: 1990-06-12
Publication date: 1991-07-17
Also published as: GB9013071D0; GB8913543D0

Abstract

A composite cutting blade (2) comprises an elongate stool carrier (4) to which is attached an elongate ceramic strip (5) having a cutting edge (6). The invention also includes a hand tool incorporating such a blade, a hinged cutting device incorporating such a blade, a pair of scissors incorporating two such blades, and a gardening tool incorporating two such blades. The carrier may be recessed to receive the strip 5 which may be formed of zirconia and adhesively secured to the carrier. <IMAGE>

Description

CUTTING BLADE AND DEVICE This invention relates to a cutting blade, to a hand tool incorporating such a blade and to a hinged cutting device or tool, such as a pair of scissors, a guillotine, or gardening tools such as shears, pruners, edge trimmers incorporating such a blade(s).

Scissors for instance are known to have composite cutting blades in the form of a steel cutting blade rivetted to a cast or forged metal backing which is formed integrally with finger loops. Conventionally, the blades require not only a cutting edge (produced by grinding) but also a slightly bowed end-to-end shape (produced for instance by hand bending in a vice) so that the point of contact between the blades travels progressively from an area adjacent the fulcrum towards the tips of the blades remote from the fulcrum, and frequently the blades are inclined with respect to each other.

For certain heavy duty applications, such as poultry portioning, or the cutting of materials such as Kevlar (trade mark), steel bladed scissors require frequent re-sharpening e.g., every two days.

It is known that ceramic (zirconia) blades have a sharpness life some 1 to 4 times better than a conventional steel blade, and attempts have been made to substitute ceramic blades for steel blades in scissors, with a known proposal being for ceramic blades to be a push-fit into plastic loop handles or to have handles moulded around them.A difficulty however is the relatively brittle nature of a ceramic blade compared with a steel blade, and customer resistance to purchase such scissors, following the need to depart from a classical scissor profile in producing ceramic scissors, particularly in low-duty applications such as hairdressing where aesthetic appearance, light weight and ease of use are significant, According to a first aspect of the present invention, there is provided a composite cutting blade comprising ceramic cutting edge mounted on a carrier of non-ceramic material.

According to a second aspect of the invention of independent signif icance, there is provided a hand tool incorporating a composite cutting blade comprising ceramic cutting edge mounted on a carrier of non-ceramic material.

According to a third aspect of the invention, of independent significance there is provided a hinged cutting device comprising ceramic cutting edge mounted on a carrier of non-ceramic material.

According to a fourth aspect of the invention, of independent significance, there is provided a pair of scissors, each blade thereof being a composite cutting blade comprising ceramic cutting edge mounted on a carrier of nonceramic material and each carrier being attached to a fulcrum zone in turn attached to a looped handle.

According to a fifth aspect of the invention, of independent significance, there is provided a gardening tool, comprising a pair of composite cutting blades hinged together, each blade comprising ceramic cutting edge mounted on a carrier of non-ceramic material and each carrier being attached to a fulcrum zone, in turn attached to a handle or spigot or tang upon which a handle is mounted.

The carrier is preferably of steel, while the ceramic is preferably zirconia. Preferably the carrier is elongate and an elongate ceramic strip having a cutting edge is attached to the carrier.

Preferably, with the fourth and fifth aspects of the invention, the carrier is formed integrally with the fulcrum zone, which is formed integrally with the looped handle in the case of the third embodiment, or the handle, spigot or tang in accordance with the fourth embodiment, while the inclination of one blade with respect to the other is established by ceramic, metal or other bearing pieces at the fulcrum zone.

In the case of scissors, shears etc., the composite nature of the blade enables these products to retain their classical profiles and hence provides the elegance and familiarity of classical profiles together with the much improved edge retaining properties of ceramic blades, while a steel carrier gives mechanical protection to the ceramic blade from maltreatment such as twisting or other stressing which otherwise might result in premature failure or fracture, which may occur in some cutting applications, whilst enhancing the appearance of the ceramic strip.

Furthermore, the use of steel also for the fulcrum zone of each blade enables the pivotal connection between two blades, whether of scissors, shears etc., to be made in a conventional and hence proven manner, while the use of a ceramic bearing improves the life of this part and hence adds to the cutting life of the device.

For scissors, shears etc., the ceramic may be preformed to a bowed shape or a straight ceramic cutting edge may be fixed to a curved backing and be under tension and may be provided with mounting recesses or holes.

The carrier is preferably recessed to accommodate the strip. The recessing may be formed by forging, blanking or machining.

Preferably, the strip is secured to its steel backing or support by a suitable adhesive e.g., a high strength polymer adhesive.

The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a pair of scissors in accordance with the fourth aspect of the invention incorporating cutting blades in accordance with the first aspect of the invention; Figure 2 is a sectional view through the two blades of Figure 1; Figure 3 shows one scissors blade and part of a handle of a second embodiment; Figure 4 is a section on the line IV-IV of Figure 3; Figure 5 corresponds to Figure 3 but shows a third embodiment; and Figure 6 is a section on the line VI-VI of Figure 5.

In Figure 1, a pair of scissors 1 comprises a pair of composite blades 2 hinged together by a ceramic bearing for rotation about a pivot point 3.

Each blade 2 comprises an elongate, steel carrier 4 constituting a support or backing for an elongate ceramic strip 5 having a cutting edge 6, and being attached to a fulcrum zone 7, in turn attached to a loop handle 8, each strip extending from a tip 9 of each blade 2 to an end 1 beyond the pivot point 3, so that the entire cutting action is between the ceramic cutting edges 6.

As shown in Figure 2, each blade 2 is recessed to accommodate its strip 5, the recess being defined by two orthogonal faces 11, 12. It follows that the strip 5 is provided with complementary orthogonal faces 13, 14, and a height strength polymer adhesive is applied to faces 11, 12, and /or 13, 14, before the blade 2 and its strip 5 are brought together. Also indicated in Figure 2 are contiguous passing faces 15 on the blade 2 and 16 on the strip 5, both faces 15, 16, being formed with straight sides.

In the second embodiment illustrated in Figures 3 and 4, the blade 2 and strip 5 are formed with more complex crosssections, the strip 5 being attached to its blade 2 mechanically by at least one dove tail projection and groove arrangement 17, in addition to adhesive, the passing faces 15, 16, again being formed with straight sides.

In the third embodiment illustrated in Figures 5 and 6, yet further cross-sections for the blade 2 and strip 5 are employed, still with a dove tail arrangement 17, but also indicating how the "ride" can be developed by a lug 18, e.g.

of ceramic, in the fulcrum zone 7, thus avoiding the need to have the whole fulcrum zone 7 profiled to provide ride. As an alternative to the lug 18, the lug can be provided by the head of a retaining screw 19 or by a metal or plastics nib(s).

Figure 6 also indicates that, compared with Figures 2 and 4, no metallic passing face 15 exists, the ceramic passing face 16 being extended across the entire blade 2, and furthermore being curved in contrast to the planar embodiments of Figures 2 and 4.

Claims

1. A composite cutting blade comprising a ceramic cutting edge mounted on a carrier of non-ceramic material.

2. A blade as claimed in Claim 1, wherein the carrier is of steel.

3. A blade as claimed in Claim 1 or Claim 2, wherein the ceramic is zirconia.

4. A composite cutting blade as in any one of Claims 1 to 3, wherein the carrier is elongate and an elongate ceramic strip having a cutting edge is attached to the carrier.

5. A blade as claimed in any preceding Claim, wherein the carrier is recessed to accommodate the ceramic cutting edge.

6. A blade as claimed in any preceding Claim, wherein the ceramic cutting edge is secured to its carrier by a suitable adhesive.

7. A hand tool incorporating a composite cutting blade comprising a ceramic cutting edge mounted on a carrier of non-ceramic material.

8. A hand tool as claimed in Claim 7, wherein the carrier is of steel.

9. A hand tool as claimed in Claim 7 or Claim 8, wherein the ceramic is zirconia.

1. A hand tool as claimed in any one of Claims 7 to 9, wherein the carrier is elongate and an elongate ceramic strip having a cutting edge is attached to the carrier.

11. A hand tool as claimed in any one of Claims 7 to 18, wherein the carrier is recessed to accommodate the ceramic cutting edge.

12. A hand tool as claimed in any one of Claims 7 to 11, wherein the ceramic cutting edge is secured to its carrier by a suitable adhesive.

13. A hinged cutting device comprising a composite cutting blade comprising a ceramic cutting edge mounted on a carrier of non-ceramic material.

14. A device as claimed in Claim 13, wherein the carrier is of steel.

15. A device as claimed in Claim 13 or Claim 14, wherein the ceramic strip is zirconia.

16. A device as claimed in any one of Claims 13 to 15, wherein the carrier is elongate and an elongate ceramic strip having a cutting edge is attached to the carrier.

17. A device as claimed in any one of Claims 13 to 16, wherein the carrier is recessed to accommodate the ceramic cutting edge.

18. A device as claimed in any one of Claims 13 to 17, wherein the ceramic cutting edge is secured to its carrier by a suitable adhesive.

19. A pair of scissors, each blade thereof being a composite cutting blade comprising a ceramic cutting edge mounted on a carrier of non-ceramic material, and each carrier being attached to a fulcrum zone in turn attached to a looped handle.

2. A pair of scissors as claimed in Claim 19, wherein the carrier of each blade is of steel.

21. A pair of scissors as claimed in Claim 19 or 2, wherein the ceramic of each blade is zirconia.

22. A pair of scissors as claimed in any one of Claims 19 to 21, wherein the carrier is elongate and an elongate ceramic strip having a cutting edge is attached to the carrier.

23. A pair of scissors as claimed in any one of Claims 19 to 22, wherein the carrier is recessed to accommodate the ceramic cutting edge.

24. A pair of scissors as claimed in any one of Claims 19 to 23, wherein the ceramic cutting edge is secured to its carrier by a suitable adhesive.

25. A pair of scissors as claimed in any one of Claims 19 to 24, wherein the carrier of each blade is formed integrally with the fulcrum zone, which is formed integrally with the looped handle.

26. A pair of scissors as claimed in any one of Claims 19 to 25, wherein the fulcrum zone of each blade is of steel.

27. A pair of scissors as claimed in any one of Claims 19 to 26, comprising a ceramic bearing between the two blades.

28. A pair of scissors as claimed in any one of Claims 19 to 27, wherein each blade is preformed to a bowed shape.

29. A pair of scissors as claimed in any one of Claims 19 to 27, wherein each blade comprises a straight ceramic cutting edge fixed to a curved backing.

3. A pair of scissors as claimed in Claim 29, wherein the ceramic cutting edge is under tension.

31. A pair of scissors as claimed in any one of Claims 19 to 3, wherein each blade is provided with mounting recesses or holes.

32. A pair of scissors as claimed in any one of Claims 19 to 31, wherein the inclination of one blade with respect to the other is established by ceramic, metal or other bearing pieces at the fulcrum zone.

33. A pair of scissors substantially as hereinbefore described with reference to the accompanying drawings.

34. A gardening tool, comprising a pair of composite cutting blades hinged together, each blade comprising a ceramic cutting edge mounted on a carrier of non-ceramic material, and each carrier being attached to a fulcrum zone, in turn attached to a handle or spigot or tang upon which a handle is mounted.

35. A gardening tool as claimed in Claim 34, wherein the carrier is of steel.

36. A gardening tool as claimed in Claim 34 or Claim 35, wherein the ceramic is zirconia.

37. A gardening tool as claimed in any one of Claims 34 to 36 wherein the carrier is elongate and an elongate ceramic strip having a cutting edge is attached to the carrier.

38. A gardening tool as claimed in any one of Claims 34 to 37, wherein the carrier is recessed to accommodate the ceramic cutting edge.

39. A gardening tool as claimed in any one of Claims 34 to 38, wherein the ceramic cutting edge is secured to its carrier by a suitable adhesive.

4. A gardening tool as claimed in any one of Claims 34 to 39, wherein the carrier is formed integrally with the fulcrum zone which is formed integrally with the looped handle.

41. A gardening tool as claimed in any one of Claims 34 to 4, wherein the fulcrum zone of each blade is of steel.

42. A gardening tool as claimed in any one of Claims 34 to 41, comprising a ceramic bearing between the two blades.

43. A gardening tool as claimed in any one of Claims 34 to 37, wherein each blade is pre-formed to a bowed shape.

44. A gardening tool as claimed in any one of Claims 34 to 42 comprising a straight, ceramic cutting edge fixed to a curved backing.

45. A gardening tool as claimed in Claim 44, wherein the ceramic cutting edge is under tension.

46. A gardening tool as claimed in any one of Claims 34 to 45, wherein each blade is provided with mounting recesses or holes.

47. A gardening tool as claimed in any one of Claims 34 to 46, wherein the inclination of one blade with respect to the other is established by ceramic, metal, or other bearing pieces at the fulcum zone.