GB2206527A

GB2206527A - Powered cutting tool

Info

Publication number: GB2206527A
Application number: GB08715453A
Authority: GB
Inventors: Phillip William Harold Livesey
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-07-01
Filing date: 1987-07-01
Publication date: 1989-01-11
Anticipated expiration: 2007-07-01
Also published as: GB2206527B; GB8715453D0

Abstract

A powered cutting tool (10) comprises a frame (12) and handle (14), and a motor housing (16) with a reciprocating saw blade (22) pivotably attached thereto at point (18). Jaws (34) are adjustably mounted upon the frame (12) on either side of the blade (22) and are adapted to engage a workpiece such as a pipe (30). Despression of a trigger (24) activates the blade (22) and causes the housing (16) to pivot downwards such that the blade (22) passes through the pipe (30). The workpiece engaging jaws may be magnetic, and may be self locking on the workpiece. The cutting tool may be portable or in the form of a fixed machine. The cutting may alternatively be effected by a circular saw, a band saw, a laser or a plasma cutter. <IMAGE>

Description

"Powered Cutting Tool" The present invention relates to powered cutting tools and is concerned particularly, but not exclusively, with a portable power tool for cutting tubing, such as plumbing pipes or the like, in situ; and which may operate on relatively inaccessible workpieces.

Difficulties are often encountered in curing materials such as piping, tubing, electrical conduits or the like which are positioned close together or in close proximity to walls, other equipment or materials etc.

Such difficulties arise since the design of conventional hand saws and power tools requires a relatively large amount of free space around the workpiece. Accordingly, there is a requirement, particularly in the plumbing trade, for a powered cutting tool which is capable of operating in a confined space without damaging surrounding material.

It is an object of the present invention to obviate or mitigate the aforesaid difficulties and to provide a tool fulfilling such a requirement.

Accordingly, the invention provides a powered cutting tool comprising powered cutting means, means for fixedly engaging a workpiece, and means for moving said cutting means relative to said workpiece engaging means so as to pass through said workpiece.

Preferably, said workpiece engaging means comprises first and second means for engaging the workpiece on either side of said cutting means.

Preferably also, said workpiece engaging means are adapted to be spatially adjustable relative to said cutting means.

Preferably also, said first and second workpiece engaging means comprise adjustable and/or interchangeable jaws, clamps or the like adapted to grip a generally elongate workpiece, such as a tube.

It is particularly preferred that the cutting means is a linear, reciprocating saw blade extending between said first and second jaws, clamps or the like.

In a preferred embodiment, said first and second workpiece engaging means are adjustably mounted on a frame and said cutting means is mounted on a housing pivotably attached to said frame such that the cutting means may be moved controllably between said first and second workpiece engaging means.

Alternatively, the tool may comprise an existing powered cutting tool, such as.a jig-saw, adapted by the attachment of first and second workpiece engaging means on either side of the blade thereof such that the tool is movable relative to the workpiece engaging means.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein, Figs. 1 and 2 are, respectively, side and plan views of a tool embodying the invention; Fig. 3 is a further side'view of the tool of Figs.

1 and 2 after completing a cut; Fig. 4 is a side view of the tool of Figs 1 to 3 re-adjusted for a smaller workpiece; Fig. 5 is a side view of an alternative embodiment of the invention; and Fig#. 6 is a side view of a jig-saw adapted to embody the invention by means of an attachment.

Referring now to the drawings, Figs. 1 to 4 show a power tool, generally designated 10, comprising an elongate frame 12 having a handle assembly 14 at the rear end thereof and beneath which is a motor housing 16 pivotally connected to the frame 12 at a point 18 between yoke arms 20. A powered reciprocating cutting blade 22 is mounted at the forward end of the motor housing 16 and is driven by an electric motor (not shown) located therein. In use the blade 22 reciprocates in a fore and aft direction relative to the frame 12 and the motor is preferably disposed with its shaft (not shown) extending parallel to the blade 22 to minimise the width of the motor housing 16.

The handle assembly 14 includes an actuating trigger 24 which is connected to the motor housing 16 by a link member 25 pivotably connected to the lower end of the trigger 24 at a point 26 and to the motor housing 16 at a point 28 on the under side and towards the rear thereof.

Depression of the trigger firstly serves to connect the power supply to the motor (by any suitable switching means) and further depression causes the motor housing 16 and hence the blade 22 to pivot downwardly relative to the frame 12 about the point 18. The motor housing 16 is preferably biased towards its starting position (as shown in Fig. 1) by any suitable bias means (not shown) such as springs or the like so that it returns to the starting position automatically when the trigger 24 is released. Adjustable stop means (not shown) may also be provided to limit the downward movement of the cutting blade 22. Optionally magnets (not shown) may also be provided between the housing 16 and the frame 12 to releasably retain the housing 16 in the starting position.

The trigger mechanism of the tool 10 may be modified by incorporating a spring into the length of the link member 25. This would enable the trigger 24 to be fully depressed initially, whereafter the force of the spring would draw the blade 22 down through the workpiece at a constant pressure.

The tool 10 further includes means for engaging the workpiece to be cut, such as a tube 30, comprising first and second pairs of adjustable jaws 32 and 34 located at the forward end of rods 36 and 38 which in turn are adjustably mounted in guide members 40 and 42 depending from the forward end of the frame 12 on either side of the motor housing 16, such that the jaws 32 and 34 are disposed on either side of the cutting blade 22. The rods 36 and 38 are adjustable in the guides 40 and 42 in both the horizontal (fore and aft) and vertical directions. In use, the jaws 32 and 34 grip the tube 30 and the trigger 24 is depressed causing the cutting blade 22 to pass down through the tube 30.Prior to use, the position of the jaws 32 and 34 is adjusted such that the blade 22 lies just above the workpiece in its starting position and extends horizontally beyond the workpiece by a minimum distance necessary to allow the tool to cut properly; i.e. by a distance slightly greater than the amplitude of reciprocation of the blade 22 (typically 7 mm). This means that only a relatively small clearance is required behind the workpiece, allowing a pipe or the like fastened to a wall by a typical fastening clip to be cut in situ. The amplitude of reciprocation of the blade 22 might also be made variable such that it can be adjusted to suit a particular job.

The jaws 32 and 34 would normally be adjusted prior to being applied to the workpiece. This may be achieved by means of pre-set positions or marked points on the guides 40, 42 and rods 36, 38 giving appropriate horizontal and vertical settings of the jaws 32 and 34 for varying sizes of workpiece. The jaws 32 and 34 themselves may be sprung or otherwise self-locking when applied to the workpiece.

They may be released simply by pulling off, or a release mechanism may be provided comprising a mechanical linkage (not shown) connected to a further trigger or the like (not shown) in the handle assembly 14.

Interchangeable sets of jaws 32,34 may be provided to suit different sizes, or different ranges of sizes, of workpiece, and Fig. 4 shows the tool 10 fitted with jaws 32,34 which are smaller than those of Figs. 1 to 3 and engage a smaller diameter tube 44. In this case it can be seen that the jaws 32,34 have been extended and raised relative to the blade 22, as compared with Figs. 1, to suit the smaller diameter of the tube 44.

The use of the jaws 32,34 on either side of the blade 22 also serve to minimise any deformation of the workpiece which might otherwise trap the blade 22 during the cutting operation. The adjustable stop is so adjusted as to arrest further movement of the blade 22 once the upper edge thereof has cleared the bottom of the workpiece.

In the example illustrated the cutting blade 22 is a relatively small, rigid, linear saw blade which allows access to confined spaces and reduces the risk of damage to surrounding equipment or materials. The controlled and limited movement of the blade 22 when the tool 10 is clamped to the workpiece is also important in this respect.

Additionally the generally slim, elongate design of the tool 10 allows access to locations out of the reach of the operator and the tool 10 is suited for onehanded operation.

Fig 5 of the drawings shows an alternative embodiment of the invention. A tool 46 comprises a handle 48, trigger 50, motor housing 52, cutting blade 54 and adjustable jaws 56 as before. In this case, however, the reciprocating blade 54 is driven vertically through the workpiece 58 between an uppermost and a lower most position by suitable drive means (not shown), possibly driven by the main motor (not shown) which powers the reciprocating action of the blade 54. This embodiment allows the jaws 56 to be mounted on the sides of the motor housing 52 itself.

The invention may also be implemented by adapting a jig-saw 60 or the like using an attachment 62 as shown in Fig. 6. The attachment 62 comprises pairs of adjustable jaws 64 attached to the ends of rods 66 slidably mounted in guides 68 which are attachable to the base plate 70 of the jig saw 60 on either side of the vertical blade 72.

In use the saw would be pushed through the workpiece 74 by pressure applied to the jig-saw 60 by the operator.

Obviously, the relative bulk of this arrangement makes it unsuitable for workpieces in difficult situations, however it will function usefully in numerous applications.

It is particularly envisaged that the invention be embodied in a portable hand tool suitable for cutting materials in situ, however it could also be applied to fixed or semi-fixed machine tools of any size.

The tool illustrated is suitable for cutting pipes for plumbing installations, cutting damaged pipes in situ, (so enabling repairs to be carried out without unclipping or removing existing pipe runs), and cutting plastic pipes for rain water, soil and waste pipe systems, electrical cables, electrical conduit and trunking, or any other material capable of being held in the jaws.

A number of variations of the above examples are possible as follow. The linear blade 22 may be replaced by a circular blade, however such a circular blade would require a radius greater than the diameter of the workpiece so that the ability of the tool to operate in confined spaces would be reduced. Suitable flexible blades or cutting bands might also be used as could possible future developments such as laser or plasma cutters. The jaws may be adjustable and/or interchangeable as noted above and may be replaced by other suitable clamps, magnetic arrangements or the like. Also, the power source may be an electric motor (mains, battery or generator powered) as in the examples, or hydraulic, pneumatic or mechanical drivers might be used. Other variations and alternatives will be apparent to those skilled in the art.

The tool is also well suited to mass production techniques allowing an economic unit cost.

Claims

1. A powered cutting tool comprising powered cutting means, means for fixedly engaging a workpiece, and means for moving said cutting means along a predetermined path relative to said workpiece engaging so as to pass through the workpiece.

2. A tool as claimed in claim 1 wherein said workpiece engaging means comprises first and second means for engaging the workpiece on either side of said cutting means.

3. A tool as claimed in claim 1 or claim 2 wherein said workpiece engaging means are adapted to be spacially adjustable relative to said cutting means.

4. A tool as claimed in any of claims 1 to 3 wherein said workpiece engaging means comprise adjustable and/or interchangeable jaws, clamps or the like adapted to grip a generally elongate workpiece, such as a tube.

5. A tool as claimed in any of claims 2 to 4 wherein said cutting means comprises a linear, reciprocating saw blade extending between said first and second workpiece engaging means.

6. A tool as claimed in any of claims 2 to 5 wherein said first and second workpiece engaging means are adjustably mounted on a frame and said cutting means is mounted on a housing pivotally attached to said frame such that the cutting means may be moved controllably along said predetermined path between said workpiece engaging means.

7. A tool as claimed in claim 6, further including a handle affixed to an end of said frame remote from said cutting means and said workpiece engaging means, said handle having incorporated therein an actuating member operably connected to said housing such that movement of said actuating member causes said cutting means to move along said predetermined path.

8. A tool as claimed in claim 7 wherein said actuating member also serves to control a power source for said cutting means.

9. A tool as claimed in any of claims 6, 7 or 8 wherein said cutting means is powered by an electric motor located in said housing.

10. A tool as claimed in claims 7, 8 and 9 wherein said frame and said housing are of a generally slim, elongate construction, said cutting means and workpiece engaging means being disposed at one longitudinal end thereof and said handle being located at the opposite longitudinal end.

11. A tool as claimed in any of claims 2 to 5 comprising a housing having a handle located at a first end thereof and enclosing a power source for said cutting means, said workpiece engaging means being mounted at a second, opposite end thereof, and said cutting means being mounted at said second end between said workpiece engaging means and adapted to be driven along said predetermined path therebetween.

12. A tool as claimed in any of claims 2 to 5, comprising a powered jig-saw having said first and second workpiece engaging means slidably attached to a base plate thereof on either side of said cutting means.

13. A powered cutting tool substantially as hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings.

14. A powered cutting tool substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.

15. A powered cutting tool substantially as hereinbefore described with reference to Fig. 6 of the accompanying drawings.