AU652491B2

AU652491B2 - Safety device for the operation of powered tools

Info

Publication number: AU652491B2
Application number: AU27200/92A
Authority: AU
Inventors: Russell Albert Finch
Original assignee: STERLANDS Pty Ltd
Current assignee: STERLANDS Pty Ltd
Priority date: 1991-10-25
Filing date: 1992-10-21
Publication date: 1994-08-25
Anticipated expiration: 2012-10-21
Also published as: AU2720092A

Description

AUSTRALIA

Patents Act 1990 A P/00/011I 6 2 9 Tegulation 3.2 U 4 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) So S '4 TO BE COMPLETED BY APPLICANT STERLANDS PTYO LIMITED N a m e o f A p p lic a n t: A ctu a l Inv e nto S.S L HAL L.IDA YS Address for Service: 44 ASHLEY STREET, HORNSBY N.S.W. 2077, AUSTRALIA SAFETY DEVICE FOR THE OPERATION OF POWERED TOOLS In V e n tio n T itle Details of Associated Provisional Applications: Nos: PK..7 h O 991) The following statement Is a full description 'of this invention, including the best method of performing it known to me:- 1 SAFETY DEVICE FOR THE OPERATION OF POWERED TOOLS This invention relates to powered tools and principally to 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 of timber. Such saws are also used for trenching into a piece of timber.

of er 0 o e Saws for the above purposes conventionally comprise "10 a saw guide on which there is linearly movably mounted a power unit and a rotating saw blade which is driven by the power unit. 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 pf -2timber 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 installation there is a timber support bench with an upstanding abutment member or 'fence' against which a piece of timber is pressed whilst the cutting or trenching takes place. There is a *0 a powered saw as previously described and the saw guide a or .0can 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 across a the timber.

toceso *0o The saw guide can be of various types but in the following description the saw guide is an elongated member with a track in its underface and a saw o "supporting carriage is movably mounted on the track. A 20 bearing means supporting a rotatable spindle is fixed to the carriage so the axis of the spindle lies at right angles to the axis of the track. The driving means for the saw spindle can be mounted on the carriage and coupled to the saw spindle, as by driving belts, or the saw spindle can be the shaft of a motor mounted on the carriage.

J

-3- Broadly stated the invention can be said to provide a safety device to provide safe working conditions for an operator of a powered tool including a stationary tool guide means and a tool assembly engaged with the guide means and manually linearly movably relative to the guide means, said safety device requiring continuously deactivation by one hand of the operator to release the tool assembly for movement along said guide means by the other hand of the operator, said safety device including an arm pivotally mounted on said tool assembly so a working end of said arm lies in juxtaposition to a surface of said guide means extending in the direction of tool assembly movement see along said guide means, the length of said arm from its working end to its pivotal connection to said tool assembly exceeding by a predetermined amount the distance from said surface to said pivotal connection, said predetermined amount being such that with said safety device activated the working end of said arm is in contact with said surface and attempted movement of said tool assembly in a first direction will cause the working end of said arm to jam against said surface to ~prevent movement in said first direction, means to bias the working end of said one arm into contact with said surface and manually operable means to overcome said bias and move the working end of said one arm away from said surface.

p cr "7 i _I 3a 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 ro

I

a o~ o ru r 2'r C; h I. t~

I

4 relationship to a workbench.

Fig.2 is a perspective view of a typical circular saw arrangement with which the invention would be used, Fig.3 is a schematic view of a first representative arrangement including the invention and Fig.4 is a schematic view of as second representative arrangement including the invention.

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

10 The equipment as illustrated and described can be 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.

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. Extending across the workbench 1 there is a an elongated tool guide 3.

On the underface of the guide 3 there is a track of the well known dovetail type including two parallel profiled ribs 4. Encircling the guide 3 there is a tool assembly including a ring frame 5 provided with a portion with rib engaging elements 6 whereby the tool assembly can be slidably moved along the guide 3.

Suspended from the underface of the frame 5 there is a bearing assembly 7 supporting a rotatable saw spindle F a L~ iL I Ri: 1 5 8. Supported on the top of the frame 5 there is an electric motor 9 connected in conventional manner by belts to the spindle 8. Between the ribs 4 there is a smooth elongated braking surface 10. A handle 11 of a suitable form is fixed to the frame 5 to facilitate the movement of the tool assembly relative to the guide 3.

The tool assembly is conventionally designed for right hand operation and as illustrated (Fig.l) the operator will grasp the handle 11 with his right hand S 10 and draw the saw towards him to cause the saw to pass across timber resting on the bench 1 and lying against .'on the fence 2. With such an arrangement and in certain o circumstances the operator's left hand or part thereof can come to lie in the path of the saw during the sawing operation. This invention is intended to prevent this occurring and so ensure safe operation of the powered tool. This is achieved by means of a safety device which is made inoperative by the operator using his free hand, the one not used for the operation S .20 of the powered tool, to activate a safety device. The positioning of the control is such that the operator's free hand cannot lie in the path of the tool controlled by the operator's other hand. The safety device when operative will prevent the movement of the tool from a rest position to an operating position.

The safety device in the form illustrated in Fig.3 comprises an arm 12 pivotally mounted intermediate its -6ends at 13 to a bracket 14 on the ring frame 5 so a working end 15 of the arm lies in juxtaposition to the surface 10. The length of said arm from its working end 15 to the pivotal connection 13 exceeds the distance from the surface 10 to the pivotal connection 13 by a predetermined amount. The length difference ensures that with the arm end 15 in contact with the surface 10 any attempted movement of said tool assembly in the direction of the arrow B cause the arm end 15 to ID jam against the surface 10 and act as a brake against and prevent such movement.

To move the arm out of the illustrated position and allow the movement of the ring frame 5 there is a double piston and cylinder assembly 16 which is connected at one end at 17 to a bracket 18 on the ring frame 5 and at its other end at 19 to the operating end of the arm. Movement of the piston in the cylinder in a first direction A will move the arm end 15 out of engagement with the surface 10. As will be readily 20 understood positive movement in the opposite direction will result in the arm end 15 being biased into engagement with the surface 10. As an alternative, not shown, the piston and cylinder can be a single acting unit for power movement in the direction A and the bias to engage the arm end 15 with the surface can be by other means, e.g. a spring.

Fig.4 illustrates schematically an arrangement sI ii -7where the arm 12 is of a slightly different shape as would be used with a generally horizontally mounted piston and cylinder assembly rather than the generally vertical assembly of Fig.3. It is to be noted that in both cases the contact point of the arm 15 for contact with the surface 10 and the connection point 19 line on a line to one side of the pivot point 13. This is not however an essential and other configurations can be adopted.

10 This invention makes it impossible for the ring frame 5 to be moved if the normally free hand of the operator is not engaged in the release of a means for making the device described above inoperative. This is readily achieved by providing triggering means 1: whereby a supply valve for pressurised air to the piston and cylinder assembly 16 can be controlled. As illustrated in Fig.l there is a switch 20 mounted on the fence 2 and projecting in front thereof. The switch 20 is operated by urging a piece of timber against the fence and as a result the arm 12 will be pivoted to separate the arm end 15 and the surface The switch 20 would be preferably be spring loaded to the inoperative position by means sufficiently strong to ensure the timber has to be pressed against the fence. In other words the weight of the timber itself would not be sufficient to overcome the spring loading thus allowing the operator's free hand to be moved into a danger zone.

I tN- In an alternative arrangement the switch 20 can be provided for manual use. The switch would be positioned and/or constructed so that hand operation is essential thereby preventing a weight or other means being substituted for hand operation, applied to make hand operation unnecessary.

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

oo o o o o s o or a oroo ou o o on so oo oo* o roro ra ~oo r; Ir-~=i 1-

Claims

9- The claims defining the invention are as follows; i. Safety device to provide safe working conditions for an operator of a powered tool including a stationary tool guide means and a tool assembly engaged with the guide means and manually linearly movably relative to the guide means, said safety device requiring continuous±y deactivation by one hand of the operator to release the tool assembly for movement along said guide means by the other hand of the operator, said safety device including an arm pivotally mounted on said tool assembly so a worki.ng "°°end of said arm lies in juxtaposition to a surface of eu said guide means extending in the direction of tool assembly movement along said guide means, the length of said arm from its wor'iing end to its pivotal connection S0 to said tool assembly exceeding by a predetermined amount the distance from said surface to said pivotal connection, said predetermined amount being such that 0with said safety device activated the working end of oooo said arm is in contact with said surface and attempted movement of said tool assembly in a first direction °oo. will cause the working end of said arm to jam against said surface to prevent movement in said first direction, means to bias the working end of said one arm into contact with said surface and manually operable means to overcome said bias and move the working end of said one arm away from said surface. c* 11 STERLANDS R.Go 7 05.06,94 (Date) -z I; u 9a- 2. °_fety device as claimed in claim 1 wherein the means to apply and overcome said bias is a double acting fluid operated piston and cylinder assembly. 3. Safety device as claimed in claim 1 wherein the means to bias the arm is a spring and the means to o 0 Sor 0600 910 B Y /2 10 overcome the bias is a fluid operated piston and cylinder assembly. 4. Safety device as claimed in any one of claims 1 to 3 wherein said arm has the means to overcome said bias acting on said arm adjacent another end of the arm with the pivotal connection to said tool assembly intermediate said arm ends and said arm working end has an engagement portion adapted to engage said surface, the location of the connection of the bias overcoming .ooo °oo means and said engagement portion lying on a line which is offset relative to the axis of pivotal connection of said arm to said tool assembly. Safety device as claimed in any one of claims 1 to 4 wherein said tool guide includes a track and said :tool assembly is mounted in said track. 6. Safety device as claimed in claim 5 where said oeti~ track is a dovetail type slideway and said tool assembly includes a corresponding profiled dovetail S"portion slidingly engaged in said slideway. 7. Safety device as claimed in any one of claims 1 to 6 wherein said surface is a smooth surface. 8. Safety device as claimed in any one of claims 1 to 6 wherein said surface is provided along its length with a plurality of tooth like projections and said one I> 11 end of said arm is adapted in shape to engage between said projections. 9. Safety device as claimed in any one of claims 1 to 8 in combination with triggering means to operate said bias overcoming means. Safety device as claimed in claim 9 wherein said triggering means is actuated by one hand of an operator of said powered tool as part of a two hand operation of said tool nia said other operator hand moves said tool assembly along said guide means.
11. Safety device as claimed in claim 10 wherein said triggering device is actuated by the operator applying pressure to a workpiece to be machined by said tool Sassembly.
12. Safety device as claimed in any one of claims 1 to 11. as part of a saw bench comprising an elongated workpiece support and a fence against which the workpiece is held whilst work is performed on the workpiece by said powered tool, said stationary tool guide means is an elongated member which extends across said workpiece support.
13. Safety device as claimed in claim 1 as part of a saw bench comprising an elongated workpiece support and a fence against which the workpiece is held whilst work -V 12 is performed on the workpiece by said powered tool, said stationary tool guide means is an elongated member which extends across said workpiece support and includes a track extending in the length direction thereof with said surface adjacent said track, said tool assembly comprises a ring frame disposed around said elongated member with a track engaging portion allowing said ring frame to be moved along said track, a power unit mounted on said ring frame, a saw spindle rotatably mounted on said ring frame and coupled to said power unit, and where said means to move said one o a arm working end away from said surface is a fluid 6 C operated piston and cylinder assembly operated to overcome said bias by triggering means activated by an operator pressing a workpiece against said fence. o .14. Safety device to ensure safe operation of a powered tool substantially as hereinbefore described with reference to the accompanying drawings. Dated this 4th day of October, 1992 STERLANDS PTY. LIMITED By its Patent Attorneys, HALLIDAYS. A*1 t.C 1- ABSTRACT Safety device to ensure safe operation of a powered tool comprising a stationary guide and a tool assembly manually movably along the guide said device including a pivotally mounted arm (12) on the tool assembly with a working end (15) in juxtaposition to a surface (10) of the guide the length of the arm (12) from its working end (15) to its pivotal connection (13) is slightly greater than the distance from the surface (10) to the pivotal connection there is means (16) to move the arm working end (15) into and out of contact with the surface the arrangement being such that when the arm end (15) engages the surface (10) movement of the tool assembly on the guide in one direction is possible and in the opposite direction is prevented. It ~Z i \i