AU660863B1 - Safety device for the operation of a powered saw - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 863 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

NOTICE

1. The specification should describe the invention in full and the best method of performing it known to the applicant.

2. The specification should be typed on as many sheets of good quality A4 International size paper as are necessary and inserted inside this form.

3. The claims defining the invention must start on a new page. If there is insufficient space on this form for the claims, use separate sheets of paper.

The words The claims defining the invention are as follows" should appear before claim 1. After the claims the date and the name of the applicant should appear in block letters.

4. This form must be accompanied by a true and exact copy of the description, claims and drawings (if any) and an additional copy of the claims.

(see Pamphlets explaining formal requirements of specifications and drawings) TO BE COMPLETED BY APPLICANT STERLANDS PTY, LIMITED N a m e of A pplica nt: Inventor(s): Robert Keith DEWEY A ctua l nv e nto 1HA/ L L..DAY

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Address for Service: 44 ASHLEY STREET, HORNSBY N.S.W. 2077, AUSTRALIA SAFETY DEVICE FOR THE OPERATION OF A POWERED SAW Inv e ntio n T itle Details of Associated Provisional Applications: Nos: The following statement Is a full description of this invention, including the best method of performing it known to me:-

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1 SAFETY DEVICE FOR THE OPERATION OF A POWERED SAW This invention relates to powered saws used in the timber industry and particularly to saws used for cutting the ends from lengths of timber in order to obtain set length pieces or for squaring or angling the end of a length oZ timber. Such saws are also used for trenching into a pfece of timber. The invention does have other applications as will be clear from the following description.

Saws for the above purposes conventionally include a support means for a linearly movably power unit with an "associated rotating saw blade. The arrangement is such that the operator needs only one hand to operate the saw to make a cut.

In the industry it is well known that the hand not required to operate the saw has to be kept well clear of the saw and operators are well drilled in safety measures, Nevertheless, accidents do occur and the purpose of this invention is to ensure the operator has to use his two hands in operating the saw thereby ensuring the hand not normally used to move the saw cannot come into contact with the saw blade. Whilst the invention has particular relevance to saws for trenching and making square or angled end cuts across 2 timber it is adaptable and can be used as a safety device on most machines where there is a member which has to be moved manually along a track or guide member as part of a machine operation. For convenience however the present invention will be described with reference to a saw installation.

In a conventional saw bench installation there is a timber support with an upstanding abutment member or *'fence' against which a piece of timber is pressed Soo.

whilst the cutting or trenching takes place. There is 10 a powered saw as previously described and the saw guide e: o" can be positioned so that the saw when moved along the guide will pass laterally or at an angle across the timber on the saw bench to provide a square or an angled cut (either relative to the vertical or ie: e horizontal planes) across the timber.

.i The saw guide car be of various types but in the following description a particular form of saw unit has been described for convenience.

Broadly stated the invention can be said to provide a safety device for a powered tool comprising a stationary support and a tool assembly including a slide shaft with a power driven tool at one end, where the slide shaft is provided with first guide means engaged with co-operating further guide means in said support enabling the slide shaft 'to be manually 3 linearly movably relative to said support whilst restraining said slide shaft against rotary movement relative to said support, said safety device including a stop rod fixed at one end to said tool assembly and positioned parallel to the axis of said slide shaft and slideably engaged in a brake assembly, said brake assembly including an elongated clamp block holder mounted in said support with a long axis of the block holder transverse to the axis of the slide shaft and having an inner end disposed within said support and an outer end accessible from outside said support, a lateral stop rod receiving hole through the clamp block holder adjacent its inner end, a longitudinal hole into the clamp block holder from its outer end and intersecting said lateral hole, a clamp block housed in said longitudinal hole, a threaded spindle engaged in a threaded portion of said longitudinal hole with one end of said spindle bearing on said clamp block and *eoanother end of the spindle extending from and beyond the outer end of said clamp block holder, an arm fixed :to said other end of said spindle, a fluid powered actuator connecting said arm to said support to provide limited bi-directional rotary movement of said spindle respectively to cause said clamp block to engage as a brake with said stop rod and release said stop rod, and valve means to provide said brake engaged condition as a normal condition for said actuator and operable to provide said brake release condition.

4 A presently preferred embodiment of the invention will now be described with reference to the accompanying drawings in which: Fig.l is a perspective view of a representative setup where the safety device of the invention would be used, the setup including a circular saw mounted in working relationship to a workbench.

Fig.2 is an enlarged fragmentary perspective -view of the components for the clamp operation and Fig.3 is an enlarged fragmentary sectional view of the .eoo o 10 clamp of the invention.

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.oco S"It is to be understood that the drawings are for the purpose of making the invention readily understood.

The equipment as illustrated and described can be V..varied in many ways and for that reason details of some non-inventive aspects of the equipment have not been dealt with in precise detail.

.ooo.i In Fig.l there is shown a workpiece support bench 1 provided with a fence 2 upstanding from the top of the bench against which a workpiece is held whilst work is being carried out thereon. Mounted on the workbench there is a saw unit 3 comprising a base a column with a saw mounting assembly 6 mounted on the column The assembly 6 can be raised and lowered on the column by means of a positioning screw 7 supported in a collar 8 on the column 5 and engaged in a threaded hole in the assembly 6. The screw 7 can be rotated by 5 means of the handle 9. The assembly 6 includes a clamp means 10 in the form of a split collar 11 mounted on the column 5 and a clamp screw 12.

The assembly 6 includes a carriage 13 and a slide shaft 14 adapted in a manner to be described to slide in a substantially horizontal plane in and restrained against rotation relative to the carriage 13. The shaft 6 has parallel longitudinal ribs 15 which are ***supported by peripherally profiled rollers 46 mounted 0g** 10 in four compartments 16 of the carriage 13.

eeoc coo• e "Fixed to the front end of the shaft 14 there is a saw assembly 17 which includes an electric drive motor (not shown) with a drive shaft which has an axis at right e "angles to the axis of the shaft 14. The saw drive shaft is adjustable as to angle in relation to the horizontal plane by means of a releasable tilt mount 0* S• between the assembly 17 and the shaft 14. The motor shaft is not shown but a saw clamp washer 18 mounted on the shaft is illustrated projecting from a saw guard 0* 19. A representative saw blade 43 is shown and the blade 43 is aligned with a saw slot 44 in the fence 2.

The shaft 14 can be unbiased in its movement direction or can be spring biassed in the retracting direction.

The shaft 14 is moved by the operator grasping a handle, not shown, on the saw assembly 17. The shaft 14 can be releaseably locked in a required position 6 relative to the carriage 13. The means for locking the shaft 14 against movement is an integral part of the safety device of the present invention. The locking means comprises a stop rod 42 fixed to the assembly 17 at 19 and extending through a guiding opening through the carriage 13 and a clamp means 47 to releaseably grip the stop rod 42.

Fig.3 best illustrates the clamp means which comprises *a clamp block holder 20 located in a hole in the 10 carriage 13 so that the inner end of the holder 20 is S"within the carriage and the outer end of the holder is accessible from outside the carriage 13. The clamp block holder 20 is cylindrical and engages in a hole in the carriage which is stepped as shown 21,22 and the holder 20 has externally dimensioned portions 23,24 adapted to be supported in the hole sections 21,22 with clearance and a shoulder 25 of the holder 20 abutting a •shoulder 26 in the carriage 13. The engaging shoulders 25,26 axially position the holder 20 and only allow 20 mounting of the holder 20 from within an interior go cavity of the carriage 13. The stop rod 42 passes through a lateral hole 27 adjacent the inner end of the holder portion 24 and the hole 27 is intersected by a an axial hole 28 through holder 20. The hole 28 is threaded at 29 for part of its length to receive the threaded body of a spindle 30 with a smooth outer end 31 and a spigot inner end 32. Between the spigot end 32 and the stop rod 42 there is a clamp .lock 33 and as 7 will be readily understood by applying axial pressure to the block 33 through the screw connection 29,30 the stop rod 42 can be clamped between the block 33 and the surface of the hole 27.

A lever arm 34 is mounted on the spindle outer end 31 to effect the clamping part rotation of the spindle The lever arm 34 is coupled through an actuator to the carriage 16. The actuator is a double acting fluid too*.operated device, in this case an air operated piston in cylinder device. The piston .rod 37 is connected to a 6 10 block 36 and through a rod 35 to the lever arm 34. The piston rod 37 is connected to a piston in the cylinder 38 which is in turn pivotally connected to the carriage 13 at 48. The cylinder ends are coupled in known manner into a compressed air supply to effect movement of the piston in the cylinder 38 thereby to apply positive bi-directional part-rotary movement to the 0 CO •spindle 30 and thus apply pressure to the block 33 to cause it to respectively clamp the rod 42 and to release the pressure on the clamp block 33. Movement of the lever 34 in the anti-clockwise direction shown by the double headed arrow in Fig. 3 will apply pressure to the clamp block 33 and movement in the opposite direction will release the pressure.

In the rest position of the equipment the rod 42 is clamped by applying compressed air to the end of the cylinder 38 having the air line 40 and the air line 41 8 to the other end of the cylinder 38 is to exhaust.

The above position is reversed to release the clamp block 33 through a valve 45 on the fence 2. When an operator presses a workpiece against the fence 2 as a preliminary to making a cross-cut with the saw blade 43 he is required to operate the valve 45. If the valve is not operated to release the clamp block 33 the operator will be unable to move the member 14 relative to the carriage 13.

Does 0e* In this way both hands of the operator are needed in 10 order to make the saw operational.

The foregoing is a presently preferred arrangement and variations to detail may be made without departing from h* i the inventive concept herein disclosed.

Claims (2)

1. 4. mounted in said support with a long axis of the block holder transverse to the axis of the slide shaft and :having an inner end disposed within said support and an outer end accessible from outside said support, a lateral stop rod receiving hole through the clamp block holder adjacent its inner end, a longitudinal hole into the clamp block holder from its outer end and intersecting said lateral hole, a clamp block housed in said longitudinal hole, a threaded spindle engaged in a threaded portion of se I longitudinal hole with one end of said spindle bearing on said clamp block and another end of the spindle extending from and beyond the outer end of said clamp block holder, an arm fixed to said other end of said spindle, -a fluid powered 10 actuator connecting said arm to said support to provide limited bi-directional rotary movement of said spindle respectively to cause said clamp block to engage as a brake with said stop rod and release said stop rod, and valve means to provide said brake engaged condition as a normal condition for said actuator and operable to provide said brake release condition. 2. Safety device as claimed in claim 1 wherein the actuator is a double acting air operated piston in cylinder assembly with a cylinder pivotally connected to said support. 3. Safety device as claimed in claim 1 or claim 2 wherein said clamp block holder has 'a stepped cylindrical exterior which is mounted with clearance in a correspondingly stepped hole in said support with th shoulders at the steps on the clamp block holder and ooe said support hole abutting to axially position said clamp block holder in said support and only pern;I mounting of said clamp block holder in said suppoxt hole from within an interior cavity of said support with which said support hole communicates. 4. Safety device as claimed in any one of claims 1 to 3 where said power driven tool is a circular saw and said support is positioned in working juxtaposition to a saw bench including an elongated workpiece support and an elongated fence against which the workpiece is 11 held whilst it is cut by said saw ana said slide shaft moves on an axis which lies at an nigle to said fence work and said valve means is mounted adjacent said fence so as to be manually operable by a hand of a workman whilst that hand is holding the workpiece against said fence. 4. Safety device for a powered tool, substantially as hereinbefore described with reference to the accompanying drawings. o °STERLANDS PTY. LIMITED ByDated this 17th day of December, 1993rneys, S. S S S _III1__ 1 ABSTRACT Safety device to ensure safe operation of a powered tool having a support (13) for a manually linearly moveable tool assembly the safety device includes a stop rod (42) fixed to the tool assembly (17) and slideably engaged in a clamp means (47) on the support (13) and including a clamp block (33) which can be clamped against the stop rod (15) to prevent the tool assembly (17) moving. The application of a clamping force to the clamp block (33) and the release of the clamping force is achieved by part rotation of a threaded spindle The part rotation is provided by a double acting piston in cylinder unit (38) and an S. I associated valve means (45) to release the normally acting clamping force on the clamp block the valve means is positioned for operation by a workman w to wishing to move the tool assembly. *e S SS IT* S S G. 17 S5 5 *7 37 36 19555* *1 34 6 91 123 19 3.4
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