"BAND SAW APPARATUS" DESCRIPTION

The present invention relates to a band saw apparatus. FIELD OF THE INVENTION

Band saws are known in the prior art that consist of a single cutting unit. In such band saws, the item to be cut is held stationary, whilst the cutting unit travels along a frame and cuts the item. However, such single cutting unit band saws have drawbacks, e.g. they can be relatively slow in the cutting operation.

The present invention seeks to provide a band saw apparatus which has improved performance, e.g. in which the speed of the cutting operation is improved.

SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a band saw apparatus comprising: a pair of cutting units, each said cutting unit having a frame supporting a pair of wheels with an endless saw blade arranged thereon; frame means arranged to support said cutting units, said cutting units arranged to travel toward one another along said frame means; alignment means for aligning said cutting units for relative angular displacement about a horizontal axis which is substantially parallel to the cutting plane of said apparatus and for relative horizontal/lateral displacement, wherein a cutting zone is defined between said cutting units which is arranged to receive an item to be cut and said cutting units are alignable to align said endless saw blades in said cutting plane by said alignment means such that when said cutting units move toward one another a said item in said cutting zone is cut by said saw blades.

In accordance with another aspect of the present invention there is provided a tilting apparatus for a cutting unit of a band saw apparatus comprising slide means having a first

part and a second part, wherein said first part is arranged to be fixed to a frame means of said apparatus and said second part is arranged to be fixed to said cutting unit such that said second part is movable relative to said first part to thereby tilt said cutting unit about a tilt axis. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of an embodiment of a band saw apparatus in accordance with an aspect of the present invention; Figure 2 is a front end view of a cutting unit of the band saw apparatus of Figure 1 incorporating a first embodiment of a track or rails provided on opposite sides of the band saw apparatus;

Figure 3 is a front end view of a cutting unit of the band saw apparatus of Figure 1 incorporating a second embodiment of the track or rails provided on the same side of the band saw apparatus;

Figure 4 is a first elevation view showing an alignment mechanism at one location of a cutting unit of the band saw apparatus shown in Figure 2;

Figure 5 is a second elevation view of the alignment mechanism shown in Figure 4;

Figure 6 is an end view of the alignment mechanism shown in Figure 5 with the sub-frame and track;

Figure 7 is a side view of a cutting unit of the band saw apparatus of Figure 1 showing an embodiment of a tilting arrangement of the cutting unit;

Figure 8 is a front end view of the cutting unit shown in Figure 7; and,

Figure 9 and Figure 10 show first and second embodiments, respectively, of the slide assembly of the tilting arrangement of the cutting units shown in Figures 7 and 8.

DESCRIPTION OF THE INVENTION

In Figure 1 there is shown a band saw apparatus 10 comprising a pair of cutting units 12 and 14. The cutting units 12 and 14 are substantially identical. Each cutting unit 12,14

comprises a frame 16 supporting a pair of wheels 18 and 20. An endless saw blade 22 is supported on the wheels 18 and 20 of each cutting unit 12 and 14 and is driven by rotation of the wheels 18 and 20. The cutting units 12 and 14 are supported by a frame 24 of the apparatus 10, with the cutting units 12 and 14 arranged to travel along the frame 24. Alignment mechanisms 26 (shown in Figures 4,5, -and 6) are provided on each cutting unit 12, 14. The alignment mechanisms 26 enable the cutting units 12,14 to be aligned for relative angular displacement (adjustment) about a horizontal axis which is substantially parallel to the cutting plane of the apparatus 10 and for relative horizontal/lateral displacement (adjustment), i.e. about two axes (or planes) that are substantially at a right angle to one another..

Angular adjustment ensures that the saw blades 22 of the two cutting units 12 and 14 cut parallel to one another. The horizontal/lateral adjustment ensures that the cutting planes of the cutting units 12 and 14, once parallel, are aligned in the same plane. The frame 16 of each cutting unit 12 and 14 supports the wheels 18 and 20 with the wheel 18 disposed above the wheel 20 and with the wheels 18 and 20 aligned substantially parallel to the cutting plane. The wheels 18 and 20 are rotatable about axes 30 and 32, respectively, substantially perpendicular to the cutting plane. The cutting plane is the plane in which the saw blades 22 cut and is substantially parallel to the plane of the drawing sheet depicting Figure 1. Each cutting unit 12,14 is provided with guides 34 and 36 at the front (of the cutting unit 12,14) for its saw blade 22. The guides 34 and 36 are provided above and below, respectively, the level of a cutting zone 38 (shown in broken lines in Figure 1) between the cutting units 12 and 14. The guides 34 may be raised or lowered according to the height of an item 40 to be cut (shown lateral in Figure 1). The cutting zone 38 is arranged to receive an item 40 to be cut by the saw blades 22 of the cutting units 12 and 14.

The guides 34 and 36 of the cutting units 12 and 14 turn the saw blades 22 into the cutting plane between the guides 34 and 36. The saw blades 22 pass around and behind

the wheels 18 and 20 at right angles to the cutting plane. This can be seen in Figure 1 where the saw blades 22 are seen side-on between the guides 34 and 36 of each cutting unit 12,14 and edge on where they pass around and behind the wheels 18 and 20 of each cutting unit 12,14. Between the wheels 18 and guides 34 and between the wheels 20 and the guides 36, the saw blades 22 twist from the edge-on to side-on orientation.

The frame 24 is provided with tracks or rails 41 which support the cutting units 12 and

14 and along which the cutting units 12 and 14 move as they travel along the frame 24.

The cutting units 12 and 14 are each provided with sub-frames 42 (as can be seen in

Figures 2 and 3) which support the cutting units 12 and 14 via the frames 16 on the tracks or rails 41 at selected locations.

An alignment mechanism 26 is provided at each location at which the cutting units 12 and

14 are supported on the tracks or rails 41.

Typically, the cutting units 12 and 14 are supported at three or four locations on the tracks or rails 41. In the embodiment shown in Figures 1 and 2, the cutting unit 12 is supported at two locations on each side. In the embodiment shown in Figure 3, the cutting unit 12 is supported at four locations on the same side.

Figure 2 shows an embodiment in which a set of tracks or rails 41 is provided on each side of the apparatus 10.

Figure 3 shows an embodiment in which two sets of tracks or rails 41 are provided on the same side of the apparatus 10.

In Figure 2, the alignment mechanisms 26 are provided on opposed sides of the cutting units 12 and 14.

In Figure 3, the alignment mechanisms 26 are provided on the same side of each cutting unit 12,14. Figure 4 shows, in more detail, one of the locations at which the cutting unit 12 shown in Figure 2 is supported on the tracks or rails 41 by a sub-frame 42, along with the alignment mechanism 26 at that location. Figures 5 and 6 show aspects of the alignment mechanism 26 shown in Figure 4.

Figure 4,5 and 6 also depict one of the upper support locations and the corresponding alignment mechanisms 26 of the cutting unit 12 shown in Figure 3. The lower support locations and corresponding alignment mechanisms of the cutting unit 12 shown in Figure 3 are rotated through substantially 90° relative to the upper support locations and corresponding alignment mechanisms 26 of the cutting unit 12 shown in Figure 3.

Each sub-frame 42 supports a shaft 44. Each shaft 44 supports an engagement member, such as a flanged wheel 45 or a cluster of partially opposed wheels (not shown) or a slide (not shown), which sits on the tracks or rails 41 with reference to Figure 4, this provides lateral restraint of the alignment mechanism 26 with respect to the tracks or rails 41. In this way, the shafts 44 and flanged wheels 45, which are supported by the sub-frames 42, mount the cutting units 12 and 14 via the frames 16 on the tracks or rails 41. The alignment mechanisms 26 will now be described.

A screw-thread 46 is provided on each shaft 44. A nut 47 is provided around the screw-thread 46 in engagement with the screw-thread 46. The nut 47 is provided eccentrically around the screw-thread 46. This can be best seen in Figure 6, where the shaft 44 is shown in two positions, one in broken lines and one in solid lines, to show a relative displacement D. The displacement D represents the displacement between two positions of the nut 47, due to its eccentric mounting, when it is rotated on the shaft 44. A nut 47 is fixed to a respective sub-frame 42 that supports a cutting unit 12, 14. In this way, a nut 47 is fixed to each sub-frame 42 at selected locations at which the cutting units 12 and 14 are supported on the tracks or rails 41 by the sub-frames 42. For the embodiment shown in Figure 2, the angular displacement of the cutting units 12 and 14 about a horizontal axis approximately within the cutting plane can be adjusted using the nuts 47 of their alignment mechanisms 26. The shaft 44 (and the screw-threads 46) are maintained stationary with respect to the nuts 47, and one or more of the nuts 47 are turned as required. Due to the eccentric mounting of the nut 47 on the shaft 44 and since the nut 47 is fixed to a sub-frame 42 this causes the relevant support locations of the cutting units 12,14 to move up or down independently of one another thereby controlling

the angle of the frame/s 16 of the cutting units 12,14 relative to the frame 24, i.e. the angle of the cutting plane relative to the frame 24. One or more of the alignment mechanisms 26 of each cutting unit 12,14 may be adjusted in this manner.

The shafts 44 may be locked so that they are held stationary relative to the nuts 47 by means of lock nuts 50 provided on the screw threads 46 and bearing on the nuts 47. This can be seen in Figure 4.

The alignment mechanisms 26 can be used to adjust the horizontal/lateral displacement of the cutting units 12 and 14. For the embodiment shown in Figure 2, this is done by maintaining the nuts 47 stationary and turning the relevant shafts 44 via the screw-threads 46 of one or more alignment mechanisms 26 as required. Turning the shafts 44 in this manner causes the frame/s 16 of the cutting units 12,14 to move side ways (or left to right) relative to the frame 24. This displaces the cutting unit 12,14 laterally/horizontally. The angle of rotation of the nuts 47 can be fixed relative to a frame 16 (or sub-frame 42) to maintain them stationaiy by means of a locking screw or grub screw 48 passing through the sub-frame and seated in a groove 49 in each nut 47. A groove 49 is shown in Figures 4 and 5.

For the embodiment shown in Figure 3, lateral/horizontal displacement of the cutting units 12 and 14 is achieved using the alignment mechanisms 26 at the upper and lower support locations.

Accordingly, the nuts 47 of the alignment mechanisms 26 at the upper support locations are maintained stationary (relative to the sub-frames 42) and the shafts 44 are turned relative to the nuts 47. (At the upper locations in the embodiment shown in Figure 3, turning nuts 47 has no effect on alignment as it serves only to raise or lower the sub- frames 42 relative to the tracks or rails 41.)

The alignment mechanisms 26 at the lower support locations are oriented at 90° relative to the alignment mechanisms at the upper support locations as previously hereinbefore described. Accordingly, to achieve horizontal/lateral displacement the nuts 47 are turned

relative to the sub-frames 42. (Turning the shafts 44 will have no effect on alignment or level since this will cause the wheels 45 to move vertically and there is no mechanical interlocking between the wheels 45 and the tracks or rails 41 in the vertical plane at the lower support locations. Accordingly, to effect horizontal/lateral displacement of the cutting units 12 and 14, relative to the frame 24, without angular displacement it is necessary to adjust alignment mechanisms 26 at both the upper support locations (using the shafts 44) and the lower support locations (using the nuts 47) by the same amount of movement in the same direction. Adjustment of the angular displacement of the cutting units 12 and 14 in the embodiment shown in Figure 3 can be achieved using the alignment mechanisms 26 at the upper and lower support locations. This can be achieved in the following ways:

(i) adjust the alignment mechanisms 26 at the upper support locations as for horizontal/lateral displacement described above, i.e. by turning shafts 44, without any adjustment of the alignment mechanisms 26 at the lower support locations; or,

(ii) adjust the alignment mechanisms 26 at the lower support locations as for horizontal/lateral displacement described above, i.e. by turning nuts 47, without any adjustment of the alignment mechanisms 26 at the upper support locations; or,

(iii) adjust the alignment mechanisms 26 at both the upper and lower support locations in opposite directions.

Thus, angular displacement is effected by causing the upper and lower support locations to move relative to one another.

By adjusting the alignment mechanisms 26 at the upper and lower support locations different amounts, various combinations of horizontal/lateral and angular displacement/alignment can be obtained.

In this way, the alignment mechanism 26 can be used to adjust the cutting units 12 and 14 so that their cutting planes are aligned both angularly and horizontally/laterally.

A mechanism may also be provided to control the angle of attack of each of the saw

blades 22 of the cutting units 12 and 14. This mechanism may be tilting apparatus which tilts the cutting unit 12/14 about a tilting axis. This is shown in Figures 7-10. A better understanding of this mechanism of the present invention will be obtained by first briefly reviewing prior art mechanisms. In the following description of prior art mechanisms, the same reference numbers are used for analogous parts, but are placed in parentheses.

It is known that the angle of the cutting unit (12) of a band saw may be varied in the plane of the cut about a horizontal axis perpendicular to the plane of the cut. This results in the angle of the blade (22) approaching the item (40) to be cut being adjustable within the plane of the cut.

Such prior art mechanisms rely upon a spindle or pin or similar mechanical device being positioned at the pivot point and forming the pivot about which the cutting unit (12) may be tilted. The presence of this mechanical device prevents the pivot point or axis of the tilt from being positioned above the bottom and below the top of the cutting zone (38) or item (40) to be cut. In the prior art the pivot is usually located below the cutting zone (38). One consequence of this is that when the cutting unit (12) is tilted so that the top of the cutting unit (12 or 14) is moved toward the cutting zone (38), the blade (22) moves forward towards or into the cutting zone (38) thereby effectively reducing the cutting zone (38) or interfering with the item (40) to be cut. In contrast, the present invention does not rely upon a mechanical device to form a pivot. The tilting apparatus of the present invention (an embodiment of which is shown in Figures 7-9) is provided by an arcuate slide 51 centred upon, but remote from the tilting axis 52. The cutting unit 12 shown in Figure 7 has two such slides 51. The cutting unit 14 may also be provided with two such slides 51. Each slide 51 comprises a first part 53 which is fixed to a respective sub-frame 42 or extension 54 thereof (as shown in Figure 8) and a matching second part 56 which is fixed to another part of each cutting unit 12, 14 at, for example, their frames 16. The sub-frames 42 are clamped relative to the frames 16. This clamping is illustrated

schematically in Figure 8 by the broken lines in the sub-frames 42. This clamping is released when the tilting apparatus is to be used to adjust the angle of attack. Once the angle of attack has been set, the clamping is re-engaged.

The first part 53 of each slide 51 forms a curved surface 58 at right angles to the plane of the cutting plane. The curved surface 58 represents an arc of a circle in a plane parallel to the cutting plane and centred upon the tilting axis 52. The second part 56 of each slide 51 may be formed by a matching roller/s or wheel/s 60 (Figure 9), arcuate surface 62 (Figure 10) carried by a member 63 or other mechanical means permitting the movement of the second part 56 along the arc formed by the first part 53. The rollers or wheels 60 are rotatably mounted on shafts 61.

The angle of tilt of each cutting unit 12, 14 may be adjusted by means of a threaded spindle, screw or other known mechanical or pneumatic or hydraulic means providing a tangential thrust 64 with respect to the tilting axes 52. By these means, the tilting axis 52 of each cutting unit 12/14 may be located at a point in space remote from the means of tilting and so may be located within or may pass through other parts of the apparatus 10 or cutting zone 38 without interference. Figure 7 shows the cutting unit 12 at a first position (in solid lines) and a second position (in broken lines) to show how the slides 51 enable the cutting unit 12 to pivot about the tilting axis 52 (when the clamping between the frame 16 and sub-frames 42 is released). The cutting unit 14 is similarly provided with slides 51 for pivoting about its own tilting axis 52. In this way, the slides 51 may be used to adjust the angle of attack of the saw blades 22.

The manner of operation and use of the band saw apparatus 10 of the present invention will now be described. In use, the alignment mechanisms 26 are adjusted as previously hereindescribed to ensure that the cutting planes of the saw blades 22 of the two cutting units 12 and 14 are properly aligned. Also, the angle of attack of the saw blades 22 may be set using the tilting apparatus hereinbefore described. An item 40 to be cut is placed in position in the

cutting zone 38 and is usually clamped.

The cutting units 12 and 14 then travel along the frame 24 toward one another with the item 40 therebetween. A pushing device, e.g. a pneumatic, hydraulic or mechanical pushing device (not shown), is provided to push the cutting units 12 and 14 along the frame 24 such that the saw blades 22 (which are rotating around the respective wheels 18 and 20) are pushed through the item 40 thereby cutting the item 40.

The tendency of the saw blades 22 to move off-line in the cutting operation can be controlled by adjusting the cutting force, i.e the horizontal force that pushes the cutting units 12 and 14 toward each other, and/or the blade guides 34/36, and/or the alignment mechanisms 26 and/or 28.

Additionally, means may be provided to control the tension in the saw blades 22.

Thus, each cutting unit 12,14 has its own controls for cutting pressure, tension, angular adjustment and horizontal/lateral adjustment.

The structure of the cutting units 12 and 14 of the band saw apparatus 10 provide the cutting edges of the saw blades 22 to be at substantially the very front, i.e. the leading ends, of the respective cutting units 12 and 14. This permits the cutting units 12 and 14 to come very close toward one another from opposite directions in the cutting operation to effect simultaneous cutting of the item 40.

Additionally, the guides 34 and 36 which twist the saw blades 22 into the cutting plane can be adjusted to permit the saw blades 22 to move further forward, i.e. out from the respective cutting units 12 and 14, and/or to provide further alignment of the saw blades

22.

Once the cutting units 12 and 14 have approached each other to almost complete the cut of the item 40, one of the cutting units 12,14 retracts slightly so that the other cutting unit 12, 14 continues on a slight distance to complete the cut.

The cutting units 12 and 14 then retract to their non-operational position at the respective ends of the cutting zone 38 or the item 40 (which has now been cut).

The provision of two cutting units 12 and 14 improves the speed of the cutting operation

since two cutting units are simultaneously cutting the item 40.

The alignment mechanisms 26 enable the cutting units 12 and 14 to be angularly and horizontally/laterally adjusted to ensure that the saw blades 22 of the respective cutting units 12 and 14 are properly aligned. This ensures that the cut through the item 40 is a straight and even cut notwithstanding that the cut has been made by two blades 22 approaching from opposite directions.

Typically, the item 40 to be cut is made of metal and the saw blades 22 are made of steel with hardened tips.

Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.