GB2136340A

GB2136340A - Hand Tools

Info

Publication number: GB2136340A
Application number: GB08306379A
Authority: GB
Inventors: Ernest James Cameron-Price
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-03-08
Filing date: 1983-03-08
Publication date: 1984-09-19
Also published as: GB8306379D0

Abstract

A hand tool comprises a tubular metal support (10) and an operative part (11). A central part of the support constitutes a handle (14) while end portions of the support are partially flattened to form holders (12 and 13) which are at different orientations to the handle. The operative part (11) is of uniform thickness and may be made as a unitary whole from sintered tungsten carbide. It includes a head (17) and a tapered tongue (18) which can be wedged tightly into either of the holders. <IMAGE>

Description

SPECIFICATION Hand Tools This invention relates to hand tools. Examples of hand tools to which the present invention is applicable are scrapers, chisels and files.

A well known and widely used type of hand tool comprises an operative part, and a wooden handle, the operative part including a head for engagement with the work and a tang which is retained in a hole in the handle by friction or by other means.

An aim of the present invention is to provide an improved form of hand tool, and to enable certain advantages to be obtained, some of which are outlined below.

From one aspect the present invention consists in a hand tool comprising a support and an operative part, the support comprising a length of metal tube, at least one end portion of which has been partially flattened to form a holder, and another part of which constitutes handle means, either constituting at least part of a handle or being connected to a handle, and the operative part having a head, which in use either is brought into operative engagement with such work or carries a working component which is brought into operative engagement with such work, and a tongue at least part of which is of generally tapered shape in plan, the arrangement being such that the tongue is or can be inserted into the hollow interior of the holder or of one of the holders where it is retained, without reliance on additional retaining means, owing to a wedging action between the holder and a tapered part of the tongue.

In one form of hand tool embodying the invention only one end portion of the support is partially flattened to form a holder, in which case the other end of the support may be provided with a closure such as a plug or cap. In a preferred form of hand tool, however, both end portions of the handle part art partially flattened to form holders. In this case, the holders may be shaped to receive tongues of the same shape or of different shapes. Further, the relative orientations between the holders and the handle means may be the same or different.In one preferred arrangement the holders are shaped to receive tongues of the same shape, and the relative orientations between the holders and the handle means are different; for example one holder may be aligned with the handle means while the other holder is inclined to it, or both holders may be inclined at different angles to the handle means.

With this arrangement the operative part may be mounted in either of the two holders, the choice of holder normally being determined by the nature of the job which is to be undertaken with the aid of the tool.

The arrangement is preferably such that the operative part is connected to the support in such a manner that it can be repeatedly removed and replaced. In a typical arrangement it may be necessary to give the operative part a light blow with a mallet or the like to free it from its wedged engagement with the holder. The tightness with which the operative part is gripped by the holder usually depends to a large extent on the degree to which the tongue is tapered. A suitable degree of taper for any desired tightness of grip can readily be determined by experiment. Nevertheless, it is often preferable for the angle between the tapered parts of the tongue to be between 20 and 100, a typical angle being 50.

The holder or each holder is preferably of substantially rectangular shape. In consequence, the normal arrangement is for the wedging action to arise from contact between the tongue and the holder over relatively small areas near the open mouth of the holder and at the edges thereof and along a relatively short extent of the side edges of the tongue, where those edges are at an angle to each other to give the necessary taper.

The tongue and the hollow interior of the holder or of each holder are preferably so shaped that when the operative part is assembled with support the relatively extensive principal faces of the tongue are positively located by adjacent internal faces of the associated holder over areas extending relatively far inwards from the mouth of that holder so that in use there is strong resistance to any forces tending to tilt the main plane of the tongue relatively to that holder.

Thus, in a preferred arrangement the engagement between the tongue and the interior of the associated holder required to effect the wedging action occurs over a distance extending inwards from the mouth of that holder considerably smaller than that over which the engagement occurs that is required to resist forces tending to tilt the operative part relatively to the holder.

From another aspect the present invention consists in a support for a hand tool of the kind outlined above and comprising a length of metal tube, at least one end portion of which has been partially flattened to form a holder, the hollow interior of which can receive the tongue of an operative part.

The tube from which the support is made is preferably of circular cross-section. The tube may be made from any suitable metal; it may, for example, be made from stainless steel, in which case the handle means may constitute a handle, and there may be no need to paint the handle or to provide the handle with any other form of covering or coating. If desired, however, the handle means may form at least part of the core of a handle, the outer part of which may be, for example, formed as a plastics moulding and may be ergonomically shaped.

In the manufacture of the support the end portion or each end portion that is partially flattened is preferably shaped by means of suitable press tools applied to outside surfaces of the tube, a blade-like stop being inserted into the end portion of the tube, at least during the final stages of shaping, to prevent the opposite side walls of the end portion approaching each other too closely or actually touching each other, and to assist in shaping the side walls so that they are parallel or substantially parallel to each other.

From another aspect the present invention consists in an operative part for a hand tool of the kind outlined above and comprising a head and tongue at least part of which is of generally tapered shape in plan, for the purposes referred to above.

The head of the operative part is preferably such that in use it is brought into direct operative engagement with work to be acted on by the tool.

The operative part is preferably formed as a unitary whole, and may be formed of metal or some other hard material such as tungsten carbide. Where appropriate, as for example when tungsten carbide is employed, the operative part may be formed by sintering powdered or particulate material. The head of the operative part may be of any suitable shape, but the tongue is necessarily of restricted thickness to enable it to enter the hollow interior of the holder. In a preferred arrangement the entire operative part is of uniform thickness. Preferably the tongue of the operative part is at least approximately in the shape of a symmetrical trapezium, that is a foursided figure of which two opposite sides are parallel and the other two sides are inclined in opposite directions, but at the same angle, to the parallel sides. The head, of course, stems from the longer of the two parallel sides.The corners at the ends of the shorter of the parallel sides may be rounded off; this makes it easier to introduce the tongue into the associated holder than would otherwise be the case.

An embodiment of the present invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which Figure 1 is a side view of a hand tool embodying the present invention, Figure 2 is an end view of the tool as viewed from the left of Figure 1, Figure 3 is a plan view of a support constituting part of the tool shown in Figures 1 and 2, Figure 4 is an end view of the support as viewed from the right of Figure 3, and Figure 5 is a plan view of an operative part constituting part of the tool shown in Figures 1 and 2.

The hand tool illustrated in the accompanying drawings is intended for use as a scraper and comprises a support 10 and an operative part 11.

The support 10 is formed from a length of stainless steel tube. End portions of the tube are partially flattened to form holders 12 and 13, while most of the central part of the tube remains unaltered in shape and constitutes a handle 14.

Each end portion of the tube is deformed in turn between suitable press tools. During deformation of an end portion a stop in the form of a metal blade (not shown) with tapered sides is progressively inserted into the end portion to prevent the main side walls of the end portion approaching each other too closely or touching each other. Initially, both of the end portions are aligned with the handle 14; one of the end portions, 12, remains in alignment with the handle, while the other end portion, 13, is bent relatively to the handle so as to lie at approximately 45O to its initial position. Each of the end portions 12 and 13 is of substantially rectangular shape, the rectangular side walls 15 of each end portion being mutually parallel so that the hollow interior of each end portion is of uniform thickness.The adjacent lateral edges of the side walls 1 5 of each holder are interconnected by edge portions 16, which are integral with the side walls and are of arcuate shape in cross-section, the concave faces of the edge portions facing the interior of the holder.

The operative part 1 1 is made from sintered tungsten carbide and is in the form of a plate of uniform thickness. The operative part comprises a head 17 and a tongue 18. The head 17 is shaped approximately like a trapezium, having two parallel edges interconnected by oppositely inclined edges of equal length, but with the acute angled corners rounded off, as shown at 19. The tongue 18 is also approximately in the shape of a trapezium, but in this case it is the obtuse angled corners that are rounded off. As shown at 20. The longer of the parallel edges of the tongue is integrally connected to the central part of the shorter of the parallel edges of the head.The edges of the tongue are inclined one relative to the other at an angle of substantially 5 , that is, each of the edges of the tongue is inclined at an angle of about 230 to the centre line of the operative part 11.

The thickness of the operative part 11 is such that in assembly of the tool the tongue 18 can just be slid into a selected one of the holders. The rounding off of the obtuse angled corners of the tongue assists insertion of the tongue into the holder. When the tongue is almost fully inserted into the holder its mutually inclined edges engage the edge portions of the holder near the mouth of the holder. The operative part can be pushed or gently tapped home so that the edges of the tongue are wedged tightly against the edge portions of the holder. In this way the operative part is quite securely held in the holder. When it is desired to remove the operative part a light tap with a mallet can free the operative part again.

When the tool is assembled as described the tongue extends near to the innermost end of the holder so as to provide the maximum resistance to forces which may in use tend to tilt the operative part relatively to the holder.

The tool is intended for use as a scraper, for example a paint scraper. In use, the longer of the parallel edges of the head is used for scraping flat surfaces, and the rounded edges 19 are used for scraping concave or re-entrant surfaces.

Tools of the kind illustrated may be of any suitable dimensions, typical tools have supports made from stainless steel tube of one inch (2.54 mm) outside diameter, and a wall thickness of 0.042 inches or 0.048 inches (1.07 mm or 1.22 mm respectively). The operative part of each tool is 1.5 mm thick.

Claims

1. A hand tool comprising a support and an operative part, the support comprising a length of metal tube, at least one end portion of which has been partially flattened to form a holder, and another part of which constitutes handle means, either constituting at least part of a handle or being connected to a handle, and the operative part having a head, which in use either is brought into operative engagement with work to be acted on by the tool or carries a working component which is brought into operative engagement with such work, and a tongue at least part of which is of generally tapered shape in plan, the arrangement being such that the tongue is or can be inserted into the hollow interior of the holder or of one of the holders where it is retained, without reliance on additional retaining means, owing to a wedging action between the holder and a tapered part of the tongue.

2. A hand tool according to claim 1 in which both end portions of-the handle part are partially flattened to form holders.

3. A hand tool according to claim 2 in which the holders are shaped to receive tongues of the same shape, and the relative orientations between the holders and the handle means are different

4. A hand tool according to any one of the preceding claims in which the operative part is connected to the support in such a manner that it can be repeatedly removed and replaced.

5. A hand tool according to any of the preceding claims in which the angle between the tapered parts of the tongue is between 20 and 100.

6. A hand tool according to claim 5 in which the angle between the tapered parts of the tongue is about 5 .

7. A hand tool according to any one of the preceding claims in which the holder or each holder is of substantially rectangular shape, so that wedging action arises from contact between the tongue and the holder over relatively small areas near the open mouth of the holder and at the edges thereof and along a relatively short extent of the side edges of the tongue, where those edges are at an angle to each other to give the necessary taper.

8. A hand tool according to any one of the preceding claims in which the tongue and the hollow interior of the holder or of each holder are so shaped that when the operative part is assembled with support relatively extensive principal faces of the tongue are positively located by adjacent internal faces of the associated holder over areas extending relatively far inwards from the mouth of that holder so that in use there is strong resistance to any forces tending to tilt the main plane of the tongue relatively to that holder.

9. A hand tool according to any one of the preceding claims in which the operative part is such that in use it is brought into direct operative engagement with work to be acted on by the tool.

10. A hand tool according to claim 9 in which the operative part is formed as a unitary whole.

1 A hand tool according to claim 10 in which the operative part is formed by sintering powdered or particulate material.

12. A hand tool substantially as hereinbefore described with reference to the accompanying drawings.

1 3. A support for a hand tool as claimed in any one of the preceding claims and comprising a length of metal tube, at least one end portion of which has been partially flattened to form a holder, the hollow interior of which can receive the tongue of an operative part.

14. A support according to claim 13 and substantially as hereinbefore described with reference to Figures 1, 2, 3 and 4 of the accompanying drawings.

1 5. An operative part for a hand tool as claimed in any one of claims 1 to 12 and comprising a head and tongue at least part of which is of generally tapered shape in plan, for the purposes described.

16. An operative part according to claim 15 and substantially as hereinbefore described with reference to Figures 1, 2 and 5 of the accompanying drawings.