GB2094698A

GB2094698A - A clipper blade

Info

Publication number: GB2094698A
Application number: GB8204413A
Authority: GB
Original assignee: LISTER FARM EQUIPMENT R A Ltd
Current assignee: LISTER FARM EQUIPMENT R A Ltd
Priority date: 1981-02-13
Filing date: 1982-02-15
Publication date: 1982-09-22
Also published as: GB2094698B

Abstract

A clipper blade in the form of a comb 10 is assembled, in use, with a further clipper blade in the form of a cutter 15. The comb has mounting surfaces 13, 14 which are of torroidal, preferably spherical, curvature and over which the cutter slides. The comb has a row of teeth 12 which co-operate with teeth 16 on the cutter to effect clipping and is also formed with a number of ribs 26 transverse to the row. During assembly, the comb and cutter are urged together and the comb flexes so that the curvature of the mounting surfaces diminishes. However, in view of the ribs, there is greater resistance to flexing in said transverse plane so that where the curvature in a plane parallel to the row is diminished, the curvature in the transverse plane will diminish less. <IMAGE>

Description

SPECIFICATION A clipper blade The invention relates to a clipper blade and is particularly, but not exclusively, concerned with a clipper blade for an animal clipping device.

Animal clipping devices usually include lower and upper blades known as a comb and a cutter. The comb is normally attached to a stationary body section of a handpiece and the cutter is mounted for side-to-side reciprocal movement relative to the comb; drive for the cutter being effected by drive means on or connected to the handpiece.

In order to cut efficiently the cutter and comb have to be made with great precision and, as a result, slight inaccuracies can lead to ineffective clipping action particulariy when cutting fine hair. This obviously creates manufacturing problems because the cutters and combs need to be manufactured in large quantities.

One problem in particular which can arise results from flexing of the cutter and/or comb which is intended to take place when they are assembled together; normally by means of a spring loaded screw. Excessive flexing can lead to the cutter and comb separating at their cutting edges which reduces the effectiveness of the clipper and considerable accuracy in assembling is required to ensure efficient operation. In order to ensure that each clipper operates efficiently it is common practice to test the blades before they leave the works. Whilst this ensures effective operation, it is time consuming and serves to highlight the need for improved clipper blades which will virtually ensure correct operation every time when assembled.

According to one aspect of the invention there is provided a clipper blade which, in use, is assembled with a further clipper blade co-operable therewith, said clipper blade being arranged to flex relative to the other clipper on assembly and including means which causes resistance to flexing in one direction to be greater than resistance to flexing in another direction.

Preferably a curved surface is formed on the blade which provides a surface for slidably engaging the further clipper blade and which diminishes in curvature as a result of flexing on assembly, the surface being curved in two planes and said means being arranged so that resistance to flexing in one plane is greater than the resistance to flexing in the other plane. A row of teeth may be formed along an edge of the blade and, in such a case, the means is arranged so that the resistance to flexing is relatively greater in a plane transverse to the row. The depth of the ribs is ideally around one third of the overall thickness of the clipper blade which enables the blade to flex more easily in the plane parallel to the row of teeth. We prefer to have ribs which have flat peaks that lie in a common plane before assembly.The flat peaks provide suitable surfaces for contact with an animal to be clipped. Valleys defined between the ribs preferably have flat floors. To provide smooth transitions between the valleys and the ribs and between the sides of the ribs and the peaks, curved transition surfaces may be provided.

According to another aspect of the invention there is provided a clipper including a cutter and a comb assembled therewith, the comb having a row of teeth along one edge which co-operate with a row of teeth along an edge of the cutter, the comb having surfaces along which the cutter is slidable for clipping, said surfaces prior to assembly being curved in planes transverse to and parallel with the row, the curves being diminished or eliminated during assembly by urging the cutter and comb together so that the comb will flex, the comb having stiffening means thereon so that there is greater resistance to flexing in the plane transverse to the row than in a plane parallel with the row.Preferably the curvature is substantially eliminated in the plane parallel with the row and is reduced in the plane transverse to the row so that the teeth of the cutter will be forced to climb over the teeth of the comb during use.

A clipper blade in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Figure l is a perspective view of an assembled cutter and comb shown partly broken away, the comb constituting the aforesaid clipper blade in accordance with the invention and the cutter constituting the aforesaid further clipper blade, Figure la is a cross section through the assembled cutter and comb in position on a handpiece, Figure2 is a plan view of the comb shown in Figure 1, Figure 3 is a cross section of the comb of Figure 2 on line III - lil in Figure 2 and illustrating curvature of front and rear mounting surfaces in a plane transverse to a row of teeth on the comb, Figure 4 is a view of the comb of Figure 2 in the direction of arrow IV in Figure 2 and illustrating the curvature of the rear mounting surface in a plane parallel with row of teeth, Figure 5 is an underplan view of the comb in Figures 1 to 4, drawn to a larger scale, Figure 6 is an enlarged cross section through part of the comb on the line VI - VI in Figure 5 showing the cross-sectional shape of the stiffening means, Figure 7 is a schematic side elevation of the comb and cutter arranged one below the other, Figure 8 is a view of the arrangement of Figure 7 looking in the direction of arrow VIII in Figure 7, Figure 9 is a schematic side elevation of the comb and cutter of Figure 7 in their assembled condition, and Figure 10 is a view of the assembly of Figure 9 looking in the direction of arrow X in Figures.

Referring first to Figures 1 and la a comb 10 has locating holes 11 which receive locating pins 2 on a clipper head 3 secured to a handpiece 4. The comb has a row of teeth 12 along its front edge and is formed with front and rear upstanding mounting surfaces 13, 14. The mounting surfaces 13, 14 support a cutter 15 which has a row of teeth 16 having front undersurfaces 17 slidable along mounting surface 13 and has a rear undersurface 18 slidable along mounting surface 14. The comb and cutter are held together by means of a bolt 19 having a shank which passes through a square aperture 20 in the comb, through a slot 22 in the cutter and through a bore 5 in the clipper head 3. A nut 23 is applied to the bolt with a spring 24 disposed between the nut and the clipper head.By tightening the nut to compress the spring, the cutter is urged against two spaced bearing fingers 6, the comb is urged against a bearing surface 7 and the cutter and comb are urged against each other so as to ensure close contact of the surfaces 13, 17 for efficient clipping action. The cutter is moved from side to side over the comb by means of a drive peg 8 on a shaft 9 extending from the handpiece. The drive peg 8 locates in a drive socket 25 on the cutter. The pitch of the teeth 13 is selected so as to correspond with or to be a multiple of the pitch of teeth 16 for reasons hereinafter described.

Referring next to Figures 2 to 4, the surfaces 13 and 14 of the comb and surfaces 17, 18 of the cutter are machined (preferably by grinding) to torroidal curves (preferably spherical curves) each having a radius of curvature R of, for example, 37.5 to 47.5 metres. In Figures 3 and 4the curvature of the comb is shown exaggerated for clarity. In practice the centre of each surface 13, 14may be around 0.015 - 0.0195 mm below its sides (distance A in Figure 4), and may be around 0.003 - 0.004 mm below the uppermost surface of the centre teeth 12 (distance A' in Figure 3).

The underside of the comb 10 is corrugated so as to define alternate ribs 26 and valleys 27 extending transverse to the row of teeth 12. Typical but non-limiting dimensions (mm) for the corrugated underside (Figure 6) are as follows: B 0.55 F 5.0 - 5.2 C 1.245 G 1.45-1.55 D 2.45 Y 15 E 5.76 The ribs may be of any other convenient cross-sectional form and in depth may be around one third of the overall thickness of the comb. The ribs have flat peaks 26' which lie substantially in the same plane prior to assembly with the cutter. The valleys have flat floors 27'. Curved surfaces of radius B extend between the sides of the ribs and the peaks and floors.

The ribs providing a stiffening means for the comb which control the degree of flexing of the comb when it is assembled with the cutter as will now be described with reference to Figures 7 to 10.

Figures 7 and 8 show how the surfaces 13, 14 are disposed relative to the surfaces 17, 18 prior to assembly and screw-down of nut 23.

As the nut 23 is screwed down to compress the spring 24 as in Figures 9 and 10 the unsupported centre portions of the comb and cutter are urged towards each other and the curvatures of interengaging surfaces 13,14 and 17,18 begin to diminish. When sufficient pressure is applied by the nut and spring, the curvatures of the surfaces 13, 14 and 17, 18 in a plane parallel with the row of teeth 12, i.e. the direction of movement of the cutter, diminishes to zero as shown in Figure 10. The curvature of surfaces 17, 18 in a transverse plane will also diminish substantially to zero. However, due to the stiffening ribs 26, the curvature of the surfaces 13, 14 in the transverse plane is still present as in Figure 9 though it will have diminished slightly from its original curvature.In view of that remaining curvature, and in view of the relationship between the pitches of teeth 13 and 16, the teeth 16 will tend to drop slightly into the gaps between the teeth 12 during side-to-side movement of the cutter. During such movement, the teeth 16 are forced to climb over the adjacent teeth 12.

This interference action ensures that any hair, however fine, will be cut. Provided that a certain amount of curvature is retained in the transverse plane efficient clipping action is ensured. Bearing in mind that the amount of such residual curvature is not too critical the setting of the nut 23 is likewise not too critical and setting of the clipper blade is thereby greatly simplified. If the cutter is sufficiently stiff, its curvature may not diminish to zero during tightening of the nut which may result in the surfaces 13, 14 taking on an opposite curvature in the parallel plane as the comb is drawn towards the cutter. In such a case there will be greater interference between the outer teeth than those towards the centre of the comb and cutter.Of course, excessive screwdown of the nut could eventually reduce the residual curvature in the transverse plane to zero and the "climbing" action of the teeth 16 would be substantially reduced and possibly lost.

Nevertheless, the clipper would still be very useful for general animal clipping work.

Mere stiffening the comb overall eg by making it thicker throughout will obviously cause the comb curvature to diminish more slowly. However such construction does not provide greater resistance to flexing in the said transverse plane than in the said parallel plane.

By placing the stiffening ribs on the back of the comb they also serve to guide the clipper during use. As is well known the comb tends to warm up during use as a result of friction between itself and the cutter.

However, ribs 26 are useful in that they prevent full face contact between the warm comb and the animal.

Instead of placing the stiffening ribs on the underside of the surface they could be arranged on the upper side as indicated in broken lines at 26' in Figure 2 and the cutter would rest on them. The width of the ribs adjacent the edges of the cutter would be wider than the throw of the cutter so that the edges would not drop into the valleys inboard of those ribs.

Typical angles of inclination a, S for the teeth 13 as shown in Figure 3 are 30 and 20 respectively but they may be varied to suit the particular application of the clipper.

Although the surfaces 13, 14 of the comb and surfaces 17, 18 of the cutter 15 are shown as being curved, the surfaces 17, 18 may be left flat if the cutter is made sufficiently stiff. In such a case it would be desirable to increase the radius of curvature on the comb by an amount which may be substantially equal to the radius of curvature which would otherwise have been formed on the cutter. However the dimensions referred to in the embodiment described have assumed that both the cutter and comb are ground with substantially equal spherical curvatures.

Whilst specific reference has been made to stiffening ribs on the comb, it is envisaged that the cutter instead of the comb could be formed so that it will have greater resistance to flexing in the plane transverse to its row of teeth than in the plane parallel with its row of teeth.

As the setting of the clipper using a comb made in accordance with the invention is less critical than hitherto, the need to test all clipper blades leaving the works is reduced and wider manufacturing tolerances may be used.

Claims

1. A clipper blade which, in use, is assembled with a further clipper blade co-operable therewith said clipper blade being arranged to flex relative to the other clipper blade on assembly and including means which causes resistance to flexing in one direction to be greater than resistance to flexing in another direction.

2. A clipper blade according to claim 1 in which a curved surface is formed on the blade which provides a surface for slidably engaging the further clipper blade and which diminishes in curvature as a result of flexing on assembly, the surface being curved in two planes and said means being arranged so that resistance to flexing in one plane is greater than the resistance to flexing in the other plane.

3. A clipper blade according to claim 2 in which a row of teeth is formed along an edge of the blade and said means is arranged so that the resistance to flexing is relatively greater in a plane transverse to the row.

4. A clipper blade according to claim 3 in which said means comprises a plurality of stiffening ribs extending transverse to the row.

5. A clipper blade according to claim 4 in which the depth of the ribs is substantially one third of the overall thickness of the clipper blade.

6. A clipper blade according to claim 4 or 5 in which the stiffening ribs have flat peaks which lie substantially in a common place when the blade is unflexed.

7. A clipper blade according to claim 6 in which a convex curved surface is defined between side walls of each rib and the flat peak.

8. A clipper blade according to claim 4,5,6 or7 in which valleys are defined between the ribs, each valley having a substantially flat floor.

9. A clipper blade according to claim 8 in which a concave curved surface is defined between a side wall of each rib and the adjacent valley floor.

10. A clipper blade according to any of claims 4 to 9 in which the ribs extend between the row of teeth and an opposite edge of the blade.

11. A clipper blade according to any preceding claim, the blade being in the form of a comb arranged to be assembled with a further blade in the form of a cutter.

12. A clipper including a comb and a cutter assembled therewith, the comb having a row of teeth along one edge of the cutter and having surfaces along which the cutter is slidable for clipping, said surfaces prior to assembly being curved in planes transverse to and parallel with the row, the curves being diminished or eliminated during assembly by urging the cutter and comb together so that the comb will flex, the comb having stiffening means thereon so that there is greater resistance to flexing in the plane transverse to the row than in the plane parallel with the row.

13. A clipper according to claim 12 in which the curvature is substantially eliminated in the plane parallel with the row and is reduced in the plane transverse to the row so that the teeth of the cutter will be forced to climb over the teeth of the comb during use.

14. A clipper blade which, in use, is assembled with a further clipper blade co-operable therewith, the clipper blade being constructed and arranged substantially as described herein with reference to the accompanying drawings.