GB1573403A

GB1573403A - Provision of handle mounts for hand tools

Info

Publication number: GB1573403A
Application number: GB5093275A
Authority: GB
Original assignee: DOBSON PARK CONSUMER PROD
Current assignee: DOBSON PARK CONSUMER PROD
Priority date: 1976-10-26
Filing date: 1976-10-26
Publication date: 1980-08-20

Description

(54) PROVISION OF HANDLE MOUNTS FOR HAND TOOLS (71) We, DOBSON PARK CONSUM ER PRODUCTS LIMITED, a British Company of Colwick Industrial Estate, Colwick, Nottingham, NG4 2BX 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 the provision of handle mounts for hand tools such as spades or shovels.

In one relatively expensive way of manufacturing spades and shovels, solid steel blanks are subjected to hot forging processes including rolling operations for producing varying cross-sectional shapes of the blade portion that enable efficient distribution and transmission of loading between a shaft attachment portion as a handle mount to a load-bearing blade portion. The greatest cross-sectional changes take place in the frog area where the blade portion meets the attachment portion and load transmission is required with minimum distortion. The resulting implement has a satisfactorily shaped blade which is strong but expensive to make.

An alternative and cheaper method of manufacture uses steel strips of uniform thickness from which integral blade and socket blanks are cut prior to bending and finish-forming. To take satisfactory loads the blade portion is stiffened in the frog area by formation of a rib at the base of the socket portion which is swaged over to make a socket after preforming on stamping tools.

The resulting "open-socket" type of implement is cheaper but not as strong or stiff as the solid, hot-forged type, and has the disadvantage of a raised rib on its front surface with a corresponding indentation of the rear face.

Previous attempts to improve the strength of the open-socket type implements without undue increase in manufacturing costs have been directed to using sheet material and tube, but the problems of making joints of satisfactory strength between the tube and the sheet material have proved to be great particularly as these joints are needed at the frog area where the loading transmission requirements are most severe.

It is an object of the invention to provide an alternative way of providing attachment means that will result in cost reductions compared with the hot forging process discussed above and yet will have advantages as to appearance and/or strength compared with the open socket type.

According to the invention there is provided a method of making a hand tool that, in use, will be subjected, at a junction between a handle mount and a working part such as a blade, primarily to bending forces, the method comprising the step of providing a handle mount on a working part of a hand tool wherein the handle mount is cast onto the working part with fusion therebetween in a casting step.

As used herein the term "fusion" is intended to require merging of the materials of the working part and the handle mount resulting from some degree of melting of the former by the latter in the casting step.

The working part may be placed in a die with an attachment area of the portion extending into a cavity in the die, and molten metal is then introduced into the cavity during the die casting step to be shaped to form at least part of the attachment means.

Any bending or forging of the working part as a whole to achieve a desired shape will generally, but not necessarily, be performed after the pressure die casting step, as will any required heat treatment.

Methods of the invention may therefore be readily put into effect using a die within which a preferably, though not necessarily, flat blade portion is clamped between two surfaces, preferably leaving free only the area to be covered by the frog, at which position the die will form a cavity to receive molten metal in the pressure die casting step. The cavity may, if desired, place frog stiffening material only on the front, that is the load-bearing face, of the blade portion.

In the die casting step for a steel blade, molten steel can be forced into the cavity to cause local melting of the blade material so that, on cooling, the blade material and the molten steel merge to form a solid mass.

Other aspects concern hand tools made by methods of the invention, namely with handle mounts pressure die cast onto a working part.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows a cut away, part-sectional and part perspective view of a desired form for one embodiment of the invention; Figure 2 is a section on lines II-II of Figure 3 but also showing diagrammatically die casting details; Figure 3 is a front view of the embodiment of Figure 1; Figure 4 is a section on lines IV-IV of Figure 5 and showing diagrammatically die casting details; and Figure 5 is a front view of an embodiment showing an alternative tang-type arrangement.

In Figure 1, a blade element 10 is formed of a generally rectangular stamping from steel stock, and is indicated in Figure 1 by the continuous hatching lines as being consolidated with upwardly extending attachment means 11 to form a generally triangular solid stiffened mass at the frog portion 12. The upward extension of the handle mount is shown forming an integral socket 13. As drawn, the relatively rearwardly extending parts of the implement are shown in solid lines whereas the other, cut away, parts are indicated by dashed lines with part of the original blade element 10, that is before consolidation, having its position indicated by chain dash lines.

Figure 1 also shows a curved edge profile for the blade 10 at its end remote from the frog portion 12 and this may be cut at the stamping step. Any bending operations to achieve a desired blade conformation are, with advantage, preformed after a pressure die-casting step in which the handle mount 11 is provided on the blade element 10.

Figure 3 shows a front view from which it will be apparent that the blade 10 is stamped from the sheet with its end arcuate. It is, however, to be understood that other shapes of blade are possible, for example, round or heart shaped.

Figure 2 includes a section on the lines II-II of Figure 3 but distinguishes between the blade element 10 and the frog portion 12 in order to indicate the way in which the latter is die cast onto the blade element. It is however repeated that the materials of these elements are effectively fused together.

Figure 2 also shows two opposed die parts 16 and 17 which, at their lower portions, are shown engaging the front and rear faces of the blade element 10. Any suitable means may be used for clamping these die parts together to closely engage the blade 10. The rear die part 17 is formed to define both the frog portion 12 and one half of the upstanding socket portion 13. The front die part 16 may be formed only to present a matching part of the upstanding socket portion 13. As this socket portion 13 will normally be of generally circular section, however, and the die parts 16 and 17 will need to separate on the centre line of the upstanding socket portion, it is best for the front die part 16 to be formed to accommodate the blade element 10 and, possibly, an interfitting portion of the rear die part 17.

Figure 2 also shows an internal or male die part 18 by which the interior of the socket is formed. This internal die part 18 is shown displaced axially from the position at which it defines the interior of the upstanding socket portion 13. It is not essential that this relative movement be possible in practice but it may be preferred in order to facilitate disassembly of the die parts 16, 17 and removal of the finished implement.

In operation, tapered surfaces 19 at the upper part of the internal die member 18 will engage and seal against correspondingly radiused surfaces 20 of the die parts 16 and 17. Feed and vent channels for the introduction of molten metal under pressure are not specifically shown in Figure 2 as these may be at any desired positions acceptable in the pressure die moulding art. Also, of course, it may be preferred to preheat blade element 10 either directly or via the die parts 16, 17.

Figure 5 shows an alternative embodiment in which a blade element 10' has diverging side edges and a substantially square or straight end. The handle mount 11 has its upwardly extending portion 13' in the form of a tang. As shown in Figure 4 such a structure is readily cast using only front and rear die parts 16' and 17' that are suitably formed to make the frog 12 and the spigot 13', and to break on the centre line of the latter.

The diverging side edges of the blade element 10' will, for a shovel, normally be bent towards the front of the blade element.

Bending operations to achieve this will, as with any bending operations required for the embodiment of Figures 1 to 3, be performed after the pressure die casting step, as indeed will any heat treatment steps desirable to achieve the required physical characteristics of the blade element 10 and 10' and/or of the frog portions 12.

The effect of the process is to form a fusion or weld between an attachment area of the blade material and the cast-on handle mount, where the materials of each run together to make a solid frog area having an upward integral extension.

The attachment extension such as a socket, tang or straps, is integral with a stiffening, cast-on overlap onto and down a blade constituting the working part. Holes, grooves or other indentation or preformation of a sheet metal blade may assist the cast-on "welding" effect, and subsequent heat treatment can be utilized to impart a desirable strength and rigidity. The holes, grooves, cut-outs, or other indentations or preformations to receive molten metal during the die casting step are preferably made in the blade element 10, 10' at least to the rear thereof in the region of the frog portion 12, and present increased surface area to the fusion or welding action of the pressure die casting step. Especially where the handle mount material is cast into opposed portions of both faces of the blade, the holes or indentations may be adapted to provide additional mechanical interlocking.

Other casting method, may result in desired localised melting and fusion as desired, for example investment casting.

WHAT WE CLAIM IS: 1. A method of making a hand tool that, in use, will be subjected, at a junction between a handle mount and a working part such as a blade, primarily to bending forces, the method comprising the step of providing a handle mount on a working part of a hand tool wherein the handle mount is cast onto the working part with fusion therebetween in a casting step.

2. A method as claimed in claim 1, wherein molten metal used in the casting step causes local melting of metal constituting the working part.

3. A method as claimed in claim 1 or 2, wherein the handle mount is cast onto the working part by a pressure die-casting step.

4. A method as claimed in any preceding claim, wherein the working part is placed in a die with an attachment area of the part extending into a cavity in the die, and molten metal is introduced into the cavity to be shaped to form at least part of the handle mount.

5. A method as claimed in claim 4, wherein a working part in the form of a blade is located between two surfaces, the attachment area comprising a frog portion of the blade extending into the cavity which is so shaped to form, from the molten metal, an overlap part of the handle mount to extend along and stiffen the blade.

6. A method as claimed in claim 5, wherein the molten metal is applied to one side only of the blade.

7. A method as claimed in claim 5, wherein molten metal is applied to both sides of the blade.

8. A method as claimed in any preceding claim, wherein the molten metal used in the casting step is the same as the material of the working part.

9. A method as claimed in any preceding claim, wherein the working part is preformed with holes and/or indentations to recieve molten metal during the casting step.

10. A method of providing a handle mount on a working part of a hand tool substantially as described herein with reference to the accompanying drawings.

11. A hand tool having a handle mount die-cast onto a working part by a method as claimed in any preceding claim.

12. A hand tool as claimed in claim 11, wherein the handle mount comprises a socket.

13. A hand tool as claimed in claim 11, wherein the handle mount comprises a tang.

14. A hand tool as claimed in claim 11, wherein the handle mount comprises straps.

15. A hand tool substantially as described herein with reference to and as shown in the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. rear die parts 16' and 17' that are suitably formed to make the frog 12 and the spigot 13', and to break on the centre line of the latter. The diverging side edges of the blade element 10' will, for a shovel, normally be bent towards the front of the blade element. Bending operations to achieve this will, as with any bending operations required for the embodiment of Figures 1 to 3, be performed after the pressure die casting step, as indeed will any heat treatment steps desirable to achieve the required physical characteristics of the blade element 10 and 10' and/or of the frog portions 12. The effect of the process is to form a fusion or weld between an attachment area of the blade material and the cast-on handle mount, where the materials of each run together to make a solid frog area having an upward integral extension. The attachment extension such as a socket, tang or straps, is integral with a stiffening, cast-on overlap onto and down a blade constituting the working part. Holes, grooves or other indentation or preformation of a sheet metal blade may assist the cast-on "welding" effect, and subsequent heat treatment can be utilized to impart a desirable strength and rigidity. The holes, grooves, cut-outs, or other indentations or preformations to receive molten metal during the die casting step are preferably made in the blade element 10, 10' at least to the rear thereof in the region of the frog portion 12, and present increased surface area to the fusion or welding action of the pressure die casting step. Especially where the handle mount material is cast into opposed portions of both faces of the blade, the holes or indentations may be adapted to provide additional mechanical interlocking. Other casting method, may result in desired localised melting and fusion as desired, for example investment casting. WHAT WE CLAIM IS:

1. A method of making a hand tool that, in use, will be subjected, at a junction between a handle mount and a working part such as a blade, primarily to bending forces, the method comprising the step of providing a handle mount on a working part of a hand tool wherein the handle mount is cast onto the working part with fusion therebetween in a casting step.