AU755052B2

AU755052B2 - Saw

Info

Publication number: AU755052B2
Application number: AU44467/99A
Authority: AU
Inventors: Neil Andrew Murray
Original assignee: QED Pty Ltd
Current assignee: Qed Pty Ltd
Priority date: 1998-08-13
Filing date: 1999-08-12
Publication date: 2002-12-05
Anticipated expiration: 2019-08-12
Also published as: NZ337170A; CA2279657A1; AU4446799A; GB9918932D0; GB2340444A; GB2340444B

Description

Page 2 BACKGROUND OF THE INVENTION This invention relates to a saw which is suitable for use in the timber industry.

The scope of the invention is however not confined to this particular application.

15 0* o .o o oo otlo oe 1 o• e o• o o• go oil Logs come with different cross-sectional dimensions and in a timber mill the logs are sawn into planks or beams of suitable thicknesses which, generally speaking, are standard thicknesses. Prior to sawing, the logs may be scanned using any suitable technique and a decision is made, in respect of each log or block or plank, on the way in which the log is to be sawn in order to maximise the quantity of dimensioned timber which can be extracted from the log or block.

It therefore becomes necessary to adjust the position of one or more saw blades relatively to a saw table, carriage or reference point or plane in an attempt to ensure that each log or block is cut in the most efficient manner.

Circular saws are commonly used for the aforementioned sawing operations.

The circular saw blades are however relatively thick and, merely by the cutting operation, a substantial amount of sawdust or waste material is produced. Band saws are thinner and produce a smaller quantity of waste material but the position of a band saw relatively to a cutting table is not as easily adjustable as P.18666.au Page 3 is the case with a circular saw blade.

It is highly desirable to be able to adjust the cutting position of a blade, relatively to a saw table, in a reasonably short time interval for the down time while the saw is being adjusted in this way has a cost implication.

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o 1 logo go oeol o lO o*l. 2 15 oe te SUMMARY OF INVENTION The invention provides a saw which includes a first circular member mounted for rotation about a first axis, a second circular member mounted for rotation about a second axis, the first axis being spaced from the second axis, an endless saw blade which is looped around and which is frictionally engaged with the first and second members and which has a first section extending between the members on one side of a line which passes from the first to the second axis, and a second section which extends between the members on an opposed side of the said line, means for moving at least a portion of the first section laterally relatively to the line, and tension means for adjusting or substantially maintaining tension in the blade.

The moving means may cause the said portion of the first section to move relatively to a cutting table. In one form of the invention the first section is moved towards or away from the cutting table.

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Page 4 The moving means may take on any suitable form and may for example include at least two spaced guides which are movable in unison. The said portion of the blade, between the guides, may be substantially parallel to an upper surface of the table, or if required may be spaced to produce material with one or more surfaces which are not parallel to the table.

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o* ao oooo o ee o oo oooo oa. a oooe *e a cooe The guides may be movable using any suitable mechanism which, for example, may be mechanically, electrically or hydraulically operated. Preferably use is made of at least one pneumatic cylinder which acts on the guides in a controlled way.

According to requirement the moving means may be movable between two or more predetermined positions relatively to the said surface of the table. Each position corresponds to a predetermined plank or beam thickness which will be cut from a log or block on which the saw of the invention operates.

The tension means may take on any suitable form. In one example of the invention the first axis is allowed to move relatively to the second axis so that the spacing between the two axes is variable in a manner which depends on the extent to which the said portion of the first blade section is moved relatively to the said line. Thus as the said portion is displaced away from the line the axes P.18666.au Page and hence the circular members are allowed to move by a corresponding amount e.g. towards each other, and vice versa. Such movement of the circular members may be against the action of a biassing means which acts to urge the members apart so that, within acceptable limits, a substantially constant tensioning force is exerted on the blade.

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1*55 In a different form of the invention the tension means acts on the said second section of the blade in such a way that as the said portion is displaced away from the said line the second section is allowed to move towards the line, and vice versa. The means for moving the said portion of the first section may simultaneously cause a corresponding movement of the second section.

Alternatively biassing means of any appropriate type may act on the second section to ensure that, within acceptable limits, a desired tension is maintained in the saw blade.

The invention also extends to a saw arrangement which includes a cutting table, first and second circular members which are respectively mounted for rotation about first and second axes which are located on a line which is substantially fixed relatively to a surface of the cutting table, an endless band saw blade which passes around the circular members, and means for displacing at least one portion of the saw blade relatively to the cutting table surface.

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18 666.au Page 6 1 The invention further provides a method of setting an endless band saw blade relatively to a cutting table which includes the steps of deflecting a portion of the saw blade to a desired position relatively to the cutting table and adjusting or maintaining tension in the saw blade at a substantially constant value.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further described by way of examples with reference to the accompanying drawings in which: Figure 1 is a schematic side view of a saw according to one form of the invention; Figure 2 is a view similar to Figure 1 illustrating a variation according to the invention, Figure 3 is a view similar to Figure 1 illustrating a further variation of the invention, and Figure 4 is a schematic side view of another saw arrangement according to the invention.

DESCRIPTION OF PREFERRED

EMBODIMENTS

Figure 1 of the accompanying drawings schematically illustrates a saw according to the invention which, in general terms, is in the nature of a band saw.

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The saw includes a circular wheel or pulley 12 which is mounted for rotation about a first axis 14, a second wheel or pulley 16 which is mounted for rotation about a second axis 18, an endless band saw blade 20 which is looped around the wheels 12 and 16, an adjusting mechanism 22 which is engaged with the saw blade 20, and a cutting table 24.

The wheel 12 is driven by means of a motor, not shown, using techniques which are known in the art and which for this reason are not further described herein.

The wheel 16 is freely rotatable about its axis. In this example of the invention the spacing between the axes 14 and 18 is substantially fixed, although slightly cushioned by a spring or accumulator or similar device to allow the axis to move slightly relatively to each other. The axes lie on a centre line 26.

The blade 20 passes, in known manner, around the wheel 12 and around the wheel 16 and forms a first section 28 which extends between the wheels on one side of the line 26 and a second section 30 which extends between the wheels on an opposing side of the centre line 26.

The adjusting mechanism 22 has a supporting frame 32 which is located between the sections 28 and 30. Two pairs of guide wheels, respectively designated 34 and 36, are engaged with the section 28 with the saw blade P.18666.au Page 8 passing between the respective pairs of wheels. In this way a portion 38 of the blade is formed between the wheels 34 and 36 opposing an upper surface of the table 24. The portion 38 is parallel to the surface 40, or at any other desired angle relatively to the surface. Guide wheels 42 and 44 on an opposing side of the frame 32 are engaged with the second section a a 9* a.

The frame 32 is movable laterally relatively to the centre line 26, as is indicated by means of a double-headed arrow 46, by means of any suitable device 48 which acts on the frame and which is mounted to a suitable supporting structure, not shown. The device 48, in this example of the invention, is a pneumatically operated piston and cylinder arrangement which is preferably set to move the frame 32 to a position selected from two or more predetermined positions relatively to the table 24. When this takes place the distance 50 between the surface 40 and the portion 38 of the first section of the blade is adjusted.

The spacing between the portion 38 and the opposing portion of the blade in the second section 30 thereof, designated 51 in Figure 1, is such that a desired and suitable tension is created in the saw blade. This is necessary for operating reasons which are known in the art. If the portion 38 is moved towards the surface 40 the section 30 of the blade is allowed to move towards the line 26 so that the tendency for the blade tension to be increased by movement of the P.18666.au Page 9 portion 38 is countered by a corresponding movement of the section 30 and, within reason, the tension in the blade is effectively maintained. A similar process applies when the portion 38 is moved away from the surface By moving the portion 38 of the blade, in the manner described, it is possible without changing the spacing between the wheels 12 and 16 and without moving the position of the table 24 to adjust the cutting thickness 50, within limits, according to requirement. The adjustment is effected merely by operating the device 48. As indicated the device 48 may be preset to move the frame 32 to a position selected from two or more predetermined positions which correspond with predetermined cutting thicknesses 50. It is therefore possible to adjust the saw in a rapid and effective manner to take account of the dimensions of a particular log or block which is being cut so that the efficiency of timber recovery is increased. It is effective and fast to move a small section of the blade, as opposed to moving at least a substantial part of the machine or the entire table.

It is to be noted that during the adjustment process the position of the centre line 26, relatively to the cutting table surface, remains unaltered.

Figure 2 illustrates a modified saw 10A which has a number of components which are similar to those shown in Figure 1 and which bear similar reference numerals. These components are not elaborated on in the following description P.18668.au.

Page *i oe o6O oo oo o oooo oo oe o o o ooeo 15 oo oe o ooe but instead emphasis is placed on the differences between the two embodiments of the invention.

In the Figure 1 embodiment the spacing between the axes 14 and 18 is substantially fixed but cushioned using a spring or similar device. In the Figure 2 embodiment this spacing, designated 52, is variable. On the other hand the frame 32 acts only on the first section 28 of the blade. The opposing section extends linearly between wheels 12 and 16. Thus as the portion 38 is moved towards or away from the surface 40 of the table no corresponding movement in the section 30 takes place to maintain the tension in the blade. Instead the axis of the wheel 16 is allowed to move towards or away from the axis 14, in the appropriate direction, to ensure that the required degree of movement of the portion 38 can take place. Tension is maintained in the blade 20 by allowing the wheel 16 to move against the action of any appropriate biassing device 54 which acts on the axis 18. The biassing device may be a pneumatic cylinder, a bellows, any suitable pressure accumulator, a spring or any equivalent mechanism which, within reason, has a substantially constant characteristic of deflection versus biassing force.

Figure 3 illustrates a further example of a saw 10B according to the invention.

Again like reference numerals are used to designate like components and the P.1866.eu Page 11

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o. oeoo o o oooo *e o° o *o following description is intended to highlight the differences between the Figure 3 embodiment and what has been described hereinbefore.

With the saw 10B the spacing 52 between the axes 14 and 18 is fixed but cushioned and the frame 32 which is substantially similar to what is shown in Figure 2 acts only on the first section 28 of the blade. Tension is maintained in the blade 20 by means of a biassing device 56 which acts on the second section 30. The biassing device preferably has characteristics similar to those of the biassing device 54 in that, within reason, the relationship between deflection force and extent of deflection is substantially linear. Thus as the portion 38 is moved towards the surface 40 of the table the device 56 allows the section to move towards the line 26 whilst exerting a biassing force on the section which maintains a substantially constant tension in the blade. A corresponding movement takes place, but in the opposite sense, when the portion 38 is moved away from the table The essence of the invention thus lies in the ability of the saw to be adjusted relatively to the surface 40 of the table in a rapid manner to allow planks or beams of desired thicknesses to be sawn from logs so that the timber recovery rate is enhanced.

P.1 8 666.8au Page 12 Figure 4 illustrates a blade arrangement 60 of two saws, with each saw being according to any one of the previous examples. The blade arrangement includes a blade portion 38A of a first saw (not shown in full) and a blade portion 38B of a second saw (not shown in full) arranged opposing, and parallel to, each other. The portions 38A, 388 are at right angles to the upper surface 40 of the cutting table 24, and are individually movable in directions 46 as previously described herein.

The portions 38A, 38B are simultaneously used to cut a log 70 which is on the cutting table 24. The portions 38A, 388 are adjusted beforehand, according to the dimensions of the uncut log, to a spacing 72 between them for optimal wood .•oo oo recovery from the log 70. Two outer portions 74A, 74B are cut simultaneously from the log as the log 70 passes between the portions 38A, 388.

*"It is to be noted that the drawings are not to scale but schematically illustrate the 20 principles of the invention.

For the purposes of this specification the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning. Also a reference within this specification to a document is not to be taken as an admission that the disclosure therein constitutes common Sgeneral knowledge in Australia.

Claims

1. A saw which includes a first circular member mounted for rotation about a first axis, a second circular member mounted for rotation about a second axis, the first axis being spaced from the second axis, an endless saw blade which is looped around and which is frictionally engaged with the first and second members and which has a first section extending between the members on one side of a line which passes between the first and second axes, and a second section which extends between the members on an opposite side of the said line, means for moving at least a portion of the first section laterally relatively to the line from a first cutting position to at least a second cutting position spaced from the first cutting position, and tension means for adjusting or substantially maintaining tension in the blade.

2. A saw according to claim 1 wherein the moving means causes at least the said 15 portion of the first section to move relatively to a cutting table.

3. A saw according to claim 2 wherein the said portion of the first section is substantially parallel to an upper surface of the cutting table.

4. A saw according to claim 2 or 3 wherein the said portion of the first section is movable towards or away from the cutting table.

A saw according to claim 2 wherein the said portion of the first section is substantially at right angles to an upper surface of the cutting table.

6. A saw according to any one of claims 1 to 5 wherein the moving means includes ,\at least two spaced guides which are movable in unison. 14

7. A saw according to claim 6 wherein the moving means includes a mechanism which is mechanically, electronically or hydraulically operated.

8. A saw according to claim 6 wherein the moving means includes at least one pneumatic cylinder which acts on the guides.

9. A saw according to any one of claims 1 to 8 wherein the moving means is movable between two or more predetermined positions.

10. A saw according to any one of claims 1 to 9 wherein the tension means allows movement of the first axis relatively to the second axis so that the spacing between the two axes is variable in a manner which depends on the extent to which the said portion of the first blade section is moved relatively to the said line. S 15

11. A saw according to claim 10 wherein as the said portion is displaced away from the line and hence the circular members are allowed to move by a corresponding amount, towards each other, and vice versa.

12. A saw according to claim 11 wherein the said movement of the circular members towards each other is against the action of a biassing means which acts to urge the members apart so that, within acceptable limits, a substantially constant tensioning force is exerted on the blade.

13. A saw according to any one of the claims 1 to 9 wherein the tension means acts on the said second section of the blade in such a way that as the said portion is displaced away from the said line, the second section is allowed to move towards the line, and vice versa. 26/09/2002 15:38 +61-8-82723255 APT PAGE 12/13

14. A saw according to claim 13 wherein, as the second section is allowed to move, the moving means causes a corresponding movement of the second section.

A saw according to any one of claims I to 9 wherein the tension means includes biassing means which acts on the second section to ensure that, within acceptable limits, a desired tension is maintained in the saw blade.

16. A saw arrangement which includes a cutting table, first and second circular members which are respectively mounted for rotation about first and second axes which are located on a line which is substantially fixed relatively to a surface of the cutting table, an endless band saw blade which passes around the circular members, and means for displacing at least one portion of the saw blade relatively to the cutting table surface from a first cutting position to at least a second cutting position spaced from the first cutting position.

17. A saw arrangement according to claim 16 wherein, as the said portion of the saw blade is displaced towards the cutting table surface the first and second axes are allowed to move towards each other and, as the said portion of the saw blade is displaced away from the cutting table surface, the first and second axes are allowed to move apart, thereby to maintain the tension in the saw blade at a substantially constant value.

18. A saw arrangement according to claim 16 wherein as a portion of the saw blade on a first side of the said line is displaced towards the cutting table surface, at least one portion of the saw blade on a second side of the said line is displaced towards the cutting table surface. 26/09/2002 15:38 +61-8-82723255 PAGE 13/13

19. A saw substantially as disclosed herein with reference to the accompanying drawings. A saw arrangement substantially as disclosed herein with reference to the accompanying drawings. Dated this 26th day of September

2002. Q.E.D. (PROPRIETARY) LIMITED By their Patent Attorneys A. P. T. Patent and Trade Mark Attorneys 9* 0 9 C C 9*eC 0000 0000 0* 9*