WO1992016337A1

WO1992016337A1 - Hand-held tool

Info

Publication number: WO1992016337A1
Application number: PCT/GB1992/000505
Authority: WO
Inventors: Paul Warmingham Hodgson
Original assignee: British Technology Group Ltd
Priority date: 1991-03-22
Filing date: 1992-03-20
Publication date: 1992-10-01
Also published as: IE72190B1; GB9106130D0; GB2253805B; IE920905A1; GB2253805A; GB9206061D0

Abstract

A hand-held holder for edge tools in which the holder includes a butt-portion (B) shaped for gripping in the hand by the fingers, a tool holder portion (H) at a work angle to the butt-portion (B) together with a thumb pad (T) across the tool holder portion (H) for action by the thumb to exert force along the tool holder through an edge tool (20) held extending from the tool holder portion (H). The tool carrier (1) can include a resilient portion (9), at which the carrier (1) can bend to be engaged with a catch (5) in the holder in the extended position, so long as thumb action is maintained.

Description

HAND-HELD TOOL This invention relates to hand-held tools and particularly to a hand-held holder for edge tools such as those for cutting, sawing, shaping, slicing, marking or scoring where a sharp edge is used and needs to be changed and, preferably, kept covered when not in use, to protect the edge as well as a person handling the tool .

Many proposals have been made, and produced as devices, for hand tools in which a blade carrying the sharp edge is housed in an elongate handle and in many examples can be caused to project, and be retracted, lengthwise of or at an angle to the handle by operation of a knob which may be controlled by a ratchet or like device. In use the handle is gripped by being surrounded by the fingers and thumb of the whole hand and the tool used somewhat in the manner of a table-knife with some variation depending on the blade edge type. The action of the tool is achieved by the grip of the whole hand and the force and direction of the action by the flexing of the wrist. This action is not very efficient in terms of the amount of force that can be exerted and furthermore is relatively clumsy and the control of force not very finely variable.

It is an object of the invention to provide a hand-held holder for edge tools in which such shortcomings in the exertion of force are mitigated.

According to the invention there is provided a hand-held holder for edge tools in which the holder includes a butt-portion shaped for gripping in the hand by the fingers, a tool holder portion at a work angle to the butt-portion together with a thumb pad across the tool holder portion for action by the thumb to exert force along the tool holder through an edge tool held extending from the tool-holder portion. Preferably the edge tool is extendable from the tool-holder portion for use and retractable after use, conveniently on a tool carrier.

Advantageously the carrier includes a resilient portion at which the carrier can bend to be engaged with a catch in the holder in the extended position, so long as said thumb action is maintained.

Conveniently the thumb pad is formed at least in part by a tool extending element such as a tool carrier. Preferably the holder includes bias means to return an extended edge tool within the holder portion. Desirably the bias means returns an extended edge tool when force is not exerted on the thumb pad.

Advantageously when the edge tool is extendable a latch is operable to release the tool for extension. Embodiments of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows an outline plan view of a tool holder, Figure 2 shows a plan view of the opened holder with an edge tool, in this case a knife blade, retracted in to the holder, Figure 3 is a view similar to Figure 2 but with the tool extended from the holder, and

Figures 4 and 5 show an edge tool carrier forming part of the holder shown in the earlier Figures on a larger scale and respectively in plan and part cross-section along V-V. Figure 1 shows a tool holder embodying the invention of a butt portion B with a finger grip G, a thumb pad T and a tool holder portion H and blade aperture A. A screw S holds together components of the holder.

Figures 2 and 3 show an example of an interior arrangement of the tool holder of Figure 1. The references of Figure 1 are applied to the relevant portions together with more detailed references now referred to. The holder is formed of two similar parts generally symmetrical about a plane of separation parallel to the plane of Figure 1. Suitable lugs and the like for interlocking the parts when assembled are provided. This general type of construction is well-known in the art and 1s only described in detail where needed, only one part being shown.

The holder parts can be of metal or plastics with surface texture in appropriate places to provide grip.

Housed between the "sandwich" of the generally symmetrical parts in a guide way 2 is a tool carrier 1, shown in more detail in Figures 4 and 5. A spring 6 links the tool carrier 1 to the tool holder via respective pins 61, 62 on the carrier and holder.

In this specific embodiment the tool is a cutting blade with a point and a cutting edge either side of the point. As mentioned above the tool can be any one of many types and appropriate adjustments will be apparent to those skilled 1n the art.

The tool carrier 1, specifically a blade carrier, is freely slidable in guide way 2 under the action of spring 6 and thumb pressure at 3. The guide way 2 has a catch face 51 to cooperate with blade carrier 1 as described below.

Referring to in Figure 4 the blade carrier 1 has a region 8 to receive and supportingly retain a blade 20. The blade must be retained so that in use it does not wobble or otherwise move around. For example the blade may be trapped between the holder parts when these are put together. Conveniently the holder parts lock together around blade aperture A. A peg or screw 81 may fit through a hole in the blade 20. Suitable arrangements for retaining the blade are well known and will be readily apparent to those skilled in the art. A very important feature of the blade carrier is the arrangement by which the carrier is held to the holder when the carrier is pushed by pressure at 3 to extend the blade and is released for spring-urged blade retraction when the pressure is removed. In the embodiment illustrated in Figure 2 this is achieved by the hingeing provided by a slot 12, a clearance hole 11 and a resilient neck 9. When pressure is applied at 3 blade carrier 1 slides forwards in guide 2 to meet stop 21. Continued pressure bends portion 14 about neck 9 closing slot 12 and tilting portion 14 into the widened portion of guide 2 where catch face 51 is inclined to the line of guide 2. Catch part 5 of carrier 1 can then engage face 51. A relatively small pressure maintained at 3 against the resilient spring action of neck 9 holds the carrier part 5 against face 51 to give a steady support for the extended blade 20 permitting its accurate use. The closure of slot 12 effectively makes carrier 1 a single piece for force transmission in the carrier and then, through the abutting faces 5 and 51, onwards through the holder to the user's hand. The use of the thumb to maintain pressure at 3 (and 31) while the fingers of the same hand grip at G both keeps the blade extended and enables the thumb, generally the strongest digit, to exert ample force, together with the grip at G by the fingers, which grip is transmitted through the butt portion B to give the blade a good cutting action. Conveniently the ball of the thumb is used to exert the force. The whole arrangement maximises the transmission of force and the angle between the butt-portion and the tool holder is set with this in mind. This arrangement is more effective in force and control than the grip around a generally tubular body with fingers and thumb which is known at present, including those where the blade is at an angle to the handle. When thumb pressure at 3 is released the resilient neck 9 is able to turn part 14 to remove catch part 5 from catch face 51 and permit spring 6 to return blade carrier 1 to retract blade 20. The grip G is formed so that it is comfortable and effective for different sizes of hand, being wide enough not to cramp a large hand and thin enough for a small hand to encircle.

The included angle at face 5 is about 135°. This angle must not be too steep, otherwise the carrier may jam against the holder, or too shallow, when there will not be enough support.

The angle needed may depend on the materials used and should be chosen with regard to the above guidance.

Conveniently blade carrier 1 is of a plastics material, for example polypropylene, which 1s capable of repeated flexing at neck 9, without breakage. As a safety feature the angle chosen for parts 5 and 51 should not lock the carrier if neck 9 should break and destroy the hinge action but should allow the return of the blade into the housing. If required another safety feature can be provided in the form of a latch 83 which flexes at 82 to release carrier 1 in the body so that thumb pressure at 3 can then push the carrier forward. This latch can be operated by an extended finger of the hand holding the tool.

A recess 7 can be provided to hold spare blades inside the butt B.

The embodiment described above permits extension of the blade or other tool for use and automatic retraction for safety when not in use. If retraction of the blade is not required the blade can be fixed 1n the holder without the use of a blade carrier while still providing a pad area without the projecting part T (similar in overall form to Figure 3) for the thumb to exert force as described above.

The tool holder thus provides improved control of the tool with, if required, the automatic retraction of the tool into the holder for safety and tool protection and the better transmission of force from the user's hand through the thumb to the blade edge.

Claims

CLAIMS 1. A hand-held holder for edge tools in which the holder includes a butt-portion shaped for gripping in the hand by the fingers, a tool holder portion at a work angle to the butt-portion together with a thumb pad across the tool holder portion for action by the thumb to exert force along the tool holder through an edge tool held extending from the tool-holder portion.

2. A hand-held holder for edge tools according to Claim 1 in which the edge tool is extendable from the tool-holder portion for use and is retracted when thumb action ceases.

3. A hand-held holder for edge tools according to Claim 2 in which the edge tool is on a tool carrier.

4. A hand-held holder for edge tools according to Claim 3 in which the tool carrier includes a resilient portion at which the carrier can bend to be engaged with a catch in the holder in the extended position, so long as said thumb action is maintained.

5. A hand-held holder for edge tools according to Claim 2 in which the thumb pad is formed at least in part by a tool extending element such as a tool carrier.

6. A hand held holder for edge tools according to Claim 2 in which the holder includes bias means to return an extended edge tool within the holder portion.

7. A hand-held holder for edge tools according to Claim 6 in which the bias means returns an extended edge tool when force is not exerted on the thumb pad.

8. A hand-held holder for edge tools according to Claim 2 in which when the edge tool is extendable a latch is operable to release the tool for extension.