GB2331268A

GB2331268A - Rotary cutting device

Info

Publication number: GB2331268A
Application number: GB9723756A
Authority: GB
Inventors: Gary Anthony Hayes; Darren Douglas Holtam
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-11-12
Filing date: 1997-11-12
Publication date: 1999-05-19
Also published as: GB2331268A9; GB9723756D0

Abstract

A rotary cutter is mounted in a mounting which is pivotally connected to an elongate housing so as to be pivotable transversely to the housing. Transmission is provided to transmit a rotary drive from the housing to the cutter in the mountihg, the transmission being operable to permit drive of the cutter with the mounting orientated in a number of differing pivotal orientations relative to the housing.

Description

2331268 Rotary Cutting Devic The present invention is concerned with

rotary cutting devices. and particularly, but not exclusively a hand-holdable motor-driven circular saw.

There have been many previous designs for motor-driven rotary cutting devices (known as circular saws), amongst which are the arrangements described and illustrated in US Patents 4644835 and 5012582. While' such designs are generally satisfactory for many purposes, they suffer from the disadvantage that they cannot be used in some circumstances where there is spatially restricted access to the workpiece to be cut.

I have now devised an improved rotary cutting device, which permits access in a range of locations to a workpiece being cut, which helps to alleviate the disadvantage mentioned above.

According to the invention, there is provided a manually operable rotary cutting device, which device comprises: (a) an elongate housing having a longitudinal dimension; (b) drive means disposed in said housing; (c) a rotary cutting member arranged to be rotatably driven by said drive means in a first position, in which said cutting member has a drive axis transverse to said longitudinal dimension; (d) a mounting element having said cutting member mounted thereto f or rotation of said cutting member about said drive axis; (e) pivot means for permitting said mounting element to be pivoted relative to said housing about a pivot axis which is transverse both to said drive axis and to said longitudinal dimension, such that said cutting member can be moved from said first position to a second position in which said drive axis is at an acute angle to said longitudinal dimension; and (f) transmission means for connecting drive of said drive means to said cutting member, said transmission means being arranged to permit said cutting member to be driven by said drive means both in said f irst position and said second position, and in positions intermediate thereto.

It is preferred that the cutting device according to the invention is a so-called "cordless" device, in which both a battery power supply and a d. c. electric motor are provided in the housing. Typically, the battery may be of a rechargeable type. In this embodiment, the housing is preferably provided with a switch (generally an electro-mechanical switch) permitting connection between the battery power supply and the electric motor.

The housing is preferably provided with manual gripping means (which may be formed as part of the exterior surface of the housing itself). Typically the housing comprises a substantially cylindrical body.

The cutting member is typically a standard cutting disc; the disc is preferably provided with a removable blade cover or guard; such a guard can be spring-loaded to permit retraction during operation.

Bevelled gear teeth are preferably provided on the axis of the cutting member; such teeth are arranged to engage with complementary bevelled gear teeth on a free end of the transmission means.

The transmission means typically comprise a drive shaft operatively connected to the drive end of the motor, generally by means of gearing to permit a suitable choice of speed reduction f or the motor output. At least part of the drive shaft is preferably a flexible drive member, such as a helical flexure coupling.

1-1 The cutting member is preferably mounted on a nose element for rotation of the cutting member about an axis which is substantially perpendicular to the longitudinal axis of the housing. The nose element itself is pivotally mounted to the housing, typically by a pivot pin which is closer to the motor than the flexible part of the flexible drive member is. The pivot pin or other pivot connection for the nose element is preferably such that the nose element can pivot about an axis which is substantially perpendicular both to the longitudinal axis of the housing and to the axis of rotation of the cutting member.

The invention will now be further described in a specific embodiment by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a cutting device according to the invention in a first configuration; Figure 2 is a perspective view similar to that of Figure 1 showing the cutting device in a second configuration; Figure 3 is a cut-away view showing the internal working parts of the cutting device of Figures 1 and 2; Figure 3a is a detailed view of a part of the cutting device as shown in Figures 1 to 3;-- Figure 4 is a longitudinal sectional view of the cutting device of Figures 1 to 3a; and Figure 5 is a sectional view perpendicular to the sectional plane of Figure 4.

Referring to the drawings, there is shown a rotary cutting device 1 comprising a hand holdable motor driven circular saw.

The device comprises a main elongate cylindrical housing 2 carrying an electric drive motor 3. A battery power pack 4 is mounted to the rear of cylindrical housing 2. The 1 1 forward portion of housing 2 is provided with a nose 6 which is pivotally mounted relative to the housing 2 and provided with a lock 5 arranged to secure nose 6 relative to the axis of housing 2 in a selected pivotal orientation relative to the longitudinal axis of housing 2.

Nose 6 carries a circular rotatably driven cutting disc 7 secured by a releasable threaded bolt 8. A cutter guard 9 Is provided which is generally annular in configuration having ends spaced ends permitting a sector of the disc 7 to be exposed. Housing 2 is provided with an electrical switch 10 controlling operation of the drive motor 3.

The drive transmission from motor 3 to the rotary cutting disc 7 comprises appropriate step down gearing 12,13 mounted in the housing on suitable bearings. The input shaft 16 to the step down gearing extends to a helical f lexure coupling 15 which connects with a rotatable,output shaft 14, but permits relative angular movement of output shaft 14 relative to input shaft 16 as nose 6 pivots relative to housing 2. The end of shaft 14 is provided with a first bevelled gear 17a which meshes with a second bevelled gear 17b pt6vided with an output lug 18 to which cutting disc 7 is 'secured. The rotational axis of output lug 18 and output shaft 14 are oriented substantially at right angles as a result of the bevelled gear 17a, 17b arrangement.

The arrangement permits the drive to cutter disc 7 to be maintained whilst nose 6 is pivoted relative to housing 2 for a range of cutting applications.

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Claims

Claims:

A manually operable rotary cutting device, which devi comprises:

(a) an elongate housing having a longitudinal dimension; (b) drive means disposed in said housing; (c) a rotary cutting member arranged to be rotatably driven by said drive means in a first position, in which said cutting member has a drive axis transverse to said longitudinal dimension; (d) a mounting element having said cutting member mounted thereto for rotation of said cutting member about said drive axis; (e) pivot means for permitting said mounting element to be pivoted relative to said housing about a pivot axis which is transverse both to said drive axis and to said longitudinal dimension, such that said cutting member can be moved from said first position to a second position in which said drive axis is at an acute angle to said longitudinal dimension; and, (f) transmission means for connecting drive of said drive means to said cutting member, said transmission means being arranged to permit said cutting member to be driven by said drive means both in said first position and said second position, and in positions intermediate thereto.

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2. A device according to claim 1, wherein a battery power supply and a d. c. electric motor are provided in the housing.

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3. A device according to claim 2, wherein the battery is rechargeable.
4. A device according to any preceding claim, wherein the housing is provided with manual gripping means comprising part of the exterior surface of the housing itself.
5. A device according to any preceding claim, wherein the housing comprises a substantially cylindrical body.
6. A device according to any preceding claim, wherein the cutting member comprises a cutting disc.
7. A device according to any preceding claim, wherein the cutting inember is provided with a removable blade cover or guard.

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8. A device according to claim 7, wherein the guard is spring-loaded to permit retraction during operation.

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9. A device according to any preceding claim wherein the transmission means includes a bevelled gear arrangement.
10. A device according to any preceding claim, wherein the transmission means comprises a flexible drive member.
11. A device according to claim 10, wherein the flexible drive member permits a portion of the transmission means to flex transversely to the longitudinal direction of the housing, in concert with the mounting element.

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12. A device according'to claim 10 or claim 11, wherein the flexible drive member comprises an elongate member arranged to flex transverse to its longitudinal direction whilst simultaneously being capable of transmitting a rotary drive between spaced portions thereof.
13. A device according to any of claims 10 to 12, wherein the flexible drive member comprises a helical flexure coupling.
14. A device according to any preceding claim, wherein the cutting member is mounted on a nose element for rotation of the cutting member about an axis which is substantially perpendicular to the longitudinal axis of the housing.
15. A device according to any preceding claim, wherein the drive means comprises a drive motor having a drive shaft extending in the longitudinal direction of the housing.
16. A device according to any preceding claim, further comprising lock means arranged to secure the mounting element relative to the elongate housing in a selected relative pivotal orientation.
17. A device according to claim 16, wherein the lock means is arranged to secure the mounting element relative to the housing in a range of differing pivotal orientations.
18. A device substantially as herein described, with reference to the accompanying drawings.