GB1586984A - Chisel - Google Patents

Description

(54) CHISEL (71) We, STANLEY TOOLS LI MITED, of Woodside, Sheffield, S3 9PD, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a chisel, particularly but not solely a wood chisel, that is, a chisel for chiselling wood.

In our co-pending patent application No.

18292/77 (Serial No. 1586983) (from which the present patent application is divided) there is claimed a chisel comprising a metal blade, a metal bolster, a metal tang, a metal washer and a plastics handle, the blade being integral with the bolster and the tang, the washer being made separately from the blade, bolster and tang, the tang being held in the handle, the washer being between the handle and the bolster, the tang being of rectangular or square cross-section, the tang end remote from the blade being formed as a nose which as seeen in one plane is rounded and bulges outwardly of the part of the tang adjacent the nose.

Preferably the blade, the bolster and the tang are formed from rolled metal strip, which is an economical way of forming them, given the availability of good quality metal strip. The rolled metal strip may be flat or of bevelled section.

Preferably there is a blend (which may or may not be a radius) between the bolster and the tang and a corresponding blend between one end face of the washer and the hole in the washer. The blends avoid undue stress concentration which would occur at a sharp corner. Preferably the washer is at least four millimetres thick. in order to provide adequate buffering between the bolster and the handle.

Preferably the handle is formed by a moulding process to have a tapered hole therein into which the tang is subsequently inserted, the outer end of the hole in the handle being wider than the nose of the tang, so that insertion of the tang into the tapered hole is facilitated. The hole may be formed with longitudinally extending ribs or may be of cruciform section, for correctly locating the tang.

Alternatively, the handle may be moulded around the tang, but this is not the preferred method.

Preferably, one pair of opposite sides of the tang taper towards each other in a direction away from the blade within the handle along at least part, and preferably the whole of the length of the tang, said one plane (in which the nose is seen as mentioned above) being perpendicular to the other pair of opposite sides of the tang (so that the taper of the one pair of opposite sides of the tang is or would, but for the handle, be visible when the nose is seen as mentioned above).

According to the present invention there is provided a chisel comprising a metal blade, a metal bolster, a metal tang, a metal washer and a plastics handle, the blade being integral with the bolster and the tang, the washer being made separately from the blade, bolster and tang, the tang being held in the handle, the washer being between the handle and the bolster, the tang being of rectangular or square cross-section, in which there is a blend between the bolster and the tang and in which there is a corresponding blend between one end face of the washer and the hole in the washer.

The invention will be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a side elevation of a chisel embodying the invention; Figure 2 is an exploded view of the chisel of Figure 1; Figure 3 is a side elevation of part of the chisel of Figures 1 and 2, showing part of the blade, the tang, the bolster, and part of the handle, the bolster being sectioned and the handle being cut away; Figure 4 is a section on line IV-IV of Figure 3; Figure 5 is a section corresponding to Figure 4 of a modification; Figure 6 is a part section of the blade, bolster and handle of another modification; and Figure 7 is a diagrammatic illustration of a modified nose of the tang.

Referring to Figures 1 to 4, the illustrated chisel 10 comprises a metal blade 11, a metal bolster 12, a metal tang 13, a metal washer 14 and a plastics handle 15. The tang 13 is held in the handle 15 in a manner described herein after. As shown in Figure 4, the tang 13 is of rectangular or square cross-section.

The tang end remote from the blade 11 is formed as a nose 16 which, as seen in Figure 3, is rounded and bulges outwardly of the part 17 of the tang adjacent the nose 16.

The blade 11, bolster 12 and tang 13 are formed integrally from rolled metal strip which is flat.

The metal washer 14 is at least four millimetres thick, made separately from the blade 11, bolster 12 and tang 13. The tang 13 extends through a hole in the washer 14 as shown in Figure 3.

There is a blend 18 in the form of a radius between the bolster 12 and tang 13, for the purpose of avoiding undue stress concentration which would occur if the blend were replaced by a sharp corner. There is a corresponding blend between the bottom end face 19 of the washer 14 and the hole in the washer 14, as shown in Figure 3.

The handle 15 is formed by a moulding process to have a tapered hole 20 therein into which the tang 13 is subsequently inserted. The outer end of the hole 20, that is, the lower end of the hole 20 in Figure 3, is wider than the nose 16 of the tang so that a person making or assembling the chisel 10 can insert the tang 13 loosely into the hole 20. The smooth profile of the nose 16 should avoid broaching of the sides of the hole 20 upon insertion of the tang 13 into the hole 20.

As seen in Figure 3, one pair of opposite sides 22 and 23 of the tang 13 taper towards each other in a direction away from the blade 11, within the handle 15, along the whole of the length of the tang 13.

The washer 14. being at least four mm thick, prevents the bolster 12 from being moved further into the handle 15 in use.

should the handle 15 be subjected to heavy hammer blows. as is quite likely.

Upon insertion of the tang 13 into the hole 20, the nose 16 induces a wave of elastic deformation 24 around itself. When the tang 13 is driven fully home into the handle 15, during manufacture of the chisel, the highly stressed areas of the handle, at 25, are located in a sufficiently bulky part of the handle 15 to avoid excessive stressing of any part of the handle. This enables the handle 15 to be made of polypropylene, which otherwise exhibits the disadvantage of relaxing due to time and/or temperature if excessively stressed.Also, another disadvantage of excessively stressed plastics materials is avoided, that of marking in the form of for example whitened areas which would disfigure the product, an effect which would be pronounced if the bulk of stressed plastics material were relatively low, such as at the bolster end of the handle, which would be the case if the hole 20 at that end were not wider than the nose 16.

The material 26 immediately under the nose 16 induces a highly satisfactory degree of tang retention.

Because the width (w.l) of the tang nose 16 is narrower than the width (w.2) of the hole 20 at the bolster end of the handle 15, the tang 13 can be loosely fitted into the handle 15 as a first stage in the insertion of the tang 13 into the handle 15. When the tang 13 is forced further into the handle hole 20, interference between the nose 16 and the tapered sides 22 and 23 of the hole 20 then commences, producing the wave 24 of elastic deformation referred to above, the interference increasing progressively as the nose 16 is pushed further along the hole 20 until the bolster 12 abuts the washer 14 to inhibit further insertion.

In describing the nose 16 as being rounded, it is of course the portions 27 (which engage the sides of the hole 20) which are rounded.

For locating the tang 13 in its correct angular position, longitudinally extending ribs 28 are moulded at the sides of the hole 20.

An advantage of making the hole 20 tapered is that it is easier to produce in a moulding process due to its inherent draft.

Normally, wood chisels are wider than they are thick but on very narrow chisels, say 5 mm or less it is desirable to make the chisel blades thicker than they are wide.

Referring to the modification shown in Figure 5, by replacing the hole 20 by a hole 29 of cruciform shape, both types of blade can be fitted to a common handle.

The provision of the blend between the washer end face 19 and the washer hole to correspond with the blend at 18 between the bolster 12 and the tang 13 maximizes the area of contact between the bolster 12 and the washer 14 for the washer 14 to resist pounding forces tending to drive the bolster 12 into the handle 15. Preferably the washer 14 is made using a process such as (prefer ably) fine blanking or (less preferably) cold forming casting or hot forming, which allows the forming of a profile on the washer 14 matching the profile of the blade to tang blend.

As shown in Figure 3, the washer 14 is seated in a recess 30 in the end of the handle 15, to conceal the interface between them.

In the modification shown in Figure 6, the bolster 12 is likewise seated in a recess 31 in the end face 19A of washer 14, to conceal the interface between them.

Figure 7 illustrates a modified nose 32 of the tang, the modified nose 32 still having the rounded leading end 27, but having less of an undercut at 33 than the nose 16.

In a modification, not shown, portions of the tang sides 22 and 23 may be parallel, along about a quarter of the length of the tang 13, adjacent the bolster 12, the sides 22 and 23 tapering (as shown) only along the remaining three-quarters of the length of the tang (except at the nose 16). This may ease manufacture, since the parallel portions of the sides 22 and 23 can readily be held by a machine while shaping the blend between the blade 11 and bolster 12.

WHAT WE CLAIM IS: 1. A chisel comprising a metal blade, a metal bolster, a metal tang, a metal washer and a plastics handle, the blade being integral with the bolster and the tang, the washer being made separately from the blade, bolster and tang, the tang being held in the handle, the washer being between the handle and the bolster, the tang being of rectangular or square cross-section, in which there is a blend between the bolster and the tang and in which there is a corresponding blend between one end face of the washer and the hole in the washer.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   ably) fine blanking or (less preferably) cold forming casting or hot forming, which allows the forming of a profile on the washer 14 matching the profile of the blade to tang blend.

   As shown in Figure 3, the washer 14 is seated in a recess 30 in the end of the handle 15, to conceal the interface between them.

   In the modification shown in Figure 6, the bolster 12 is likewise seated in a recess 31 in the end face 19A of washer 14, to conceal the interface between them.

   Figure 7 illustrates a modified nose 32 of the tang, the modified nose 32 still having the rounded leading end 27, but having less of an undercut at 33 than the nose 16.

   In a modification, not shown, portions of the tang sides 22 and 23 may be parallel, along about a quarter of the length of the tang 13, adjacent the bolster 12, the sides 22 and 23 tapering (as shown) only along the remaining three-quarters of the length of the tang (except at the nose 16). This may ease manufacture, since the parallel portions of the sides 22 and 23 can readily be held by a machine while shaping the blend between the blade 11 and bolster 12.

   WHAT WE CLAIM IS:

   1. A chisel comprising a metal blade, a metal bolster, a metal tang, a metal washer and a plastics handle, the blade being integral with the bolster and the tang, the washer being made separately from the blade, bolster and tang, the tang being held in the handle, the washer being between the handle and the bolster, the tang being of rectangular or square cross-section, in which there is a blend between the bolster and the tang and in which there is a corresponding blend between one end face of the washer and the hole in the washer.