GB2367022A

GB2367022A - Apparatus for shaping and/or sharpening saw blades

Info

Publication number: GB2367022A
Application number: GB0018424A
Authority: GB
Inventors: Anthony Graham Ogden
Original assignee: DEAN SAWS Ltd
Current assignee: DEAN SAWS Ltd
Priority date: 2000-07-28
Filing date: 2000-07-28
Publication date: 2002-03-27
Also published as: GB0018424D0

Abstract

An apparatus for shaping and/or sharpening saw blades 3 comprises a support 1 for an elongate saw blade, means 7 for retaining the saw blade in position on the support, and grinding means 19 for shaping and/or sharpening the saw blade. The grinding means 19 is positioned on mounting means 9, 11, 13 which is pivotable about an axis through hinge 13 which is substantially parallel to the longitudinal direction of the saw blade 3. Means may also be provided for securing hardened tips to the saw blade teeth.

Description

APPARATUS FOR SHAPING AND/OR SHARPENING SAW BLADES This invention relates to an apparatus for shaping and/or sharpening saw blades, such as gang saws, frame saws and band saws.

Known apparatus for shaping and/or sharpening saw blades is complicated, generally fully automatic, and therefore expensive for small to medium sized enterprises to purchase and operate. Such known apparatus is also correspondingly bulky and heavy and is not readily portable for on-site use. A further problem is that the width of saw blades is progressively reduced by grinding in the gullet between adjoining teeth.

It is therefore an object of the present invention to provide an apparatus for shaping and/or sharpening saw blades which overcomes or at least ameliorates the above problems.

According to the present invention there is provided an apparatus for shaping and/or sharpening saw blades, comprising a support for an elongate saw blade, means for retaining the saw blade in position on the support, and grinding means for shaping and/or sharpening the saw blade, the grinding means being positioned on mounting means which is pivotable about an axis substantially parallel to the longitudinal direction of the saw blade.

The support may be provided with a scissor mechanism for adjusting the working extent of the support to a range of saw blade widths.

The retaining means may comprise an over-centre clamping mechanism.

The mounting means may comprise a primary member secured to the support and a secondary member which is pivotably mounted on the primary member. The degree of pivoting may be determined by an adjustable stay. Retaining means may be provided to limit the degree of pivoting.

The grinding means may be positioned on the mounting means in such a way as to permit constrained relative movement therebetween. Relative movement may be permitted in three orthogonal directions. Thus, the grinding means may be movable in a plane which is substantially perpendicular to the body of the saw blade and which extends substantially perpendicular to the edge of the saw blade, the plane being movable in the longitudinal direction of the saw blade.

The grinding means may comprise a substantially cylindrical grinding wheel.

The grinding means may be rotatably by way of a variable speed motor.

The apparatus may include means pivotably mounted relative to the support for applying a hard metal carbide tip to a tooth of the saw blade and means for securing the tip to the tooth. The pivotably mounted means may comprise a plate having a recess formed therein for receiving the tip.

The pivotable means may be biased so as to urge the tip against the tooth. The tip may be secured to the tooth by a high frequency or resistance welder or by a gas torch. The welder or torch may be movable towards and away from the tip and may be pivotable about one or more axes.

The apparatus according to the invention can be adjusted to sharpen all lengths, widths, thicknesses and variable tooth pitches.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is an end elevational view of one embodiment of an apparatus according to the present invention; Figure 2 is a plan view of a table portion of the apparatus shown in Figure 1;

Figure 3 is an elevational view of a grinding wheel mount forming part of the apparatus of Figure 1 and taken in the direction of the arrow A in Figure 1; Figure 4 is a plan view of part of the mount shown in Figure 3; and Figure 5 is a plan view of a part of the apparatus of Figure 1 adapted to apply hard metal carbide tips to the teeth of the saw blade.

The saw blade shaping and/or sharpening apparatus shown in Figures 1 to 4 comprises a saw blade table 1 for supporting an elongate saw blade 3 in a substantially horizontal configuration. As best shown in Figure 2, the table 1 is provided with a scissor mechanism 5 which permits adjustment of the working extent of the table to the width of a variety of saw blades such that the cutting edge of the blade extends beyond and generally parallel to the edge of the table, the scissor mechanism 5 ensuring the rear edge of the saw blade 3 is supported parallel to the edge of the table. A clamping mechanism 7, such as an overcentre mechanism, is provided for releasably clamping the saw blade to the table. The legs of the table may be demountable or foldable to assist portability of the apparatus.

A primary support 9 for a shaping and/or sharpening mechanism extends generally horizontally from the edge of the table 1 beyond the cutting edge of the saw blade. Pivotably mounted on the primary support 9 is a secondary support 11, the secondary support being pivotable about a hinge 13 adjacent to the edge of the table 1, the axis of the hinge extending generally parallel to the edge of the table and therefore generally parallel to the longitudinal direction of the saw blade. An adjustable stay 15 is provided (ideally at each side of the secondary support 11) to secure the secondary support at a selected angle relative to the primary support 9. The stay 15 may comprise a bolt or the like threaded through the secondary support and engageable with the primary support. The stay 15 may engage with the primary support in a manner which inhibits movement in the axial direction of the hinge, for example the stay may engage in a slot provided in the primary support and extending in a direction perpendicular to the axial direction of the hinge 13. A retaining member (not shown), such as a hold-down bolt, may be provided for limiting pivoting movement of the secondary support 11 such that, in combination, the stay and the retaining member can lock the secondary support in a desired orientation.

As best shown in Figures 3 and 4, a grinding wheel mount 17 is provided on the secondary support 11 for mounting a grinding wheel 19 which is rotatable by way of a variable speed electric motor 21 in a manner such that the grinding

wheel can be adjusted in the X-, Y-and Z-directions (i. e. with three degrees of freedom of movement). This enables the grinding wheel to be adjusted vertically, to be adjusted laterally towards and away from the edge of the table, and laterally along the edge of the table in the axial direction of the hinge.

Although other means allowing relative movement may be employed, in the illustrated embodiment the grinding wheel mount 17 comprises a pair of parallel dovetail-shaped recesses 23 formed in the secondary support 11 and extending perpendicular to the axial direction of the hinge. A first mount member 25 is provided with corresponding dovetail-shaped projections 27 to constrain the first mount member to movement towards and away from the edge of the table (or the hinge 13). A threaded member (not shown) may extend between the secondary support 11 and the first mount member 25 to control relative movement therebetween.

The first mount member 25 is provided with an upright portion 35 having formed therein a pair of parallel dovetail-shaped recesses 29 which extend in the axial direction of the hinge 13. A second mount member 31 is provided with corresponding dovetail-shaped projections 33 to constrain the second mount member to movement in the axial direction of the hinge. A threaded member (not shown) may extend between the first mount member 25 and the

second mount member 31 to control relative movement therebetween.

The second mount member 31 is provided with a pair of parallel dovetail-shaped recesses 37 which extend in a substantially vertical position. A third mount member 39 is provided with corresponding dovetail-shaped projections 41 to constrain the third mount member to up and down movement in a vertical direction (dependent on the angle of inclination of the secondary support 11). A threaded member (not shown) may extend between the second mount member 31 and the third mount member 39 to control relative movement therebetween.

The electric motor 21, and therefore the grinding wheel 19, is secured to the third mount member 39.

Thus the pivotable mounting of the secondary support 11 allows the axis of rotation of the grinding wheel to be adjusted in a substantially vertical plane, that is a plane which is substantially perpendicular to the body of the saw blade and to the table, which extends substantially perpendicular to the edge of the saw blade and of the table.

The grinding wheel 19 as shown is a cylindrical wheel. It will be understood the relative dimensions of the wheel,

and indeed the configuration thereof, can be varied as required.

As shown in Figure 2, an indexing pin 43, which can be raised and lowered as required, is positioned adjacent to the edge of the table 1 so as to engage with a tooth of the saw blade in order to locate the saw blade in the required position for shaping and/or sharpening.

The apparatus as described can be used to dress the sides of teeth which have been subjected to a swaging operation to increase the width of the tips of the teeth relative to the remainder of the saw blade, or to shape teeth upon which a hard alloy such as that known as STELLITE (RTM) has been deposited, or to finish teeth to which hard metal carbide tips have been applied, or to sharpen any of the above types of teeth. The ability of the angle of the grinding wheel to be adjusted in a plane perpendicular to the plane of the saw blade (and of the table) and perpendicular to the edge of the saw blade (and of the edge of the table) allows the wheel to be adapted to a wide range of saw blades not only to shape or sharpen the teeth, but also to re-shape the gullet of a blade.

Moreover, the manner in which the apparatus is constructed allows the apparatus to be compact, lightweight, and therefore portable. The apparatus can therefore be transported to a location at which a saw blade requires to

be serviced or repaired rather than requiring the saw blade to be transported to the apparatus. The apparatus can be adapted additionally to apply hard metal carbide tips to the teeth of the saw blade, as illustrated in Figure 5.

Figure 5 shows a plate 45 pivotably mounted in a manner spaced from the edge of the table 1 in a plane substantially parallel to the plane of the saw blade, and curved such that a portion of the plate can be pivoted into a gullet between two adjacent teeth of a saw blade. Biasing means, such as a spring 46, is provided to bias the plate 45 into the gullet. The plate 45 is provided with a peripheral recess 47 which extends part of the thickness of the plate, the recess being dimensioned to receive a presoldered hard metal carbide tip 49 to be attached to a tooth of the saw blade. The tip can be placed in the recess 47 and the plate pivoted into position and secured in place with the tip 49 urged against the tooth. The tip and the tooth can then be heated, for example with a high frequency TIG welder (shown diagrammatically at 51), so as to attach the tip to the blade. The TIG welder may be arranged to be movable towards and away from the tip and also to be pivotable about a vertical axis and about a horizontal axis in order that the welding head can be located close to the tip to be welded. The TIG welder can then be energised for a predetermined time of about 4

seconds in order to heat the blade very locally and to attach the tip to the blade. The local heating maintains the temperature of the remainder of the blade at a low level so as to avoid any significant deterioration of the metallurgical properties of the blade. After a tip has been attached the blade can be indexed to the next tooth, or the next tooth requiring a fresh tip, and the teeth can be dressed as they are indexed past the grinding wheel.

Alternatively, a resistance welder or gas torch can be used to secure the tip.

Claims

1. An apparatus for shaping and/or sharpening saw blades, comprising a support for an elongate saw blade, means for retaining the saw blade in position on the support, and grinding means for shaping and/or sharpening the saw blade, the grinding means being positioned on mounting means which is pivotable about an axis substantially parallel to the longitudinal direction of the saw blade.

2. An apparatus as claimed in claim 1, wherein the support is provided with a scissor mechanism for adjusting the working extent of the support to a range of saw blade widths.

3. An apparatus as claimed in claim 1 or 2, wherein the retaining means comprises an over-centre clamping mechanism.

4. An apparatus as claimed in claim 1,2 or 3, wherein the mounting means comprises a primary member secured to the support and a secondary member which is pivotably mounted on the primary member.

5. An apparatus as claimed in any preceding claim, wherein the degree of pivoting of the mounting means is determined by an adjustable stay.

6. An apparatus as claimed in any preceding claim, wherein retaining means is provided to limit the degree of pivoting.

7. An apparatus as claimed in any preceding claim, wherein the grinding means is positioned on the mounting means in such a way as to permit constrained relative movement therebetween.

8. An apparatus as claimed in claim 7, wherein relative movement is permitted in three orthogonal directions.

9. An apparatus as claimed in claim 8, wherein the grinding means is movable in a plane which is substantially perpendicular to the body of the saw blade and which extends substantially perpendicular to the edge of the saw blade, the plane being movable in the longitudinal direction of the saw blade.

10. An apparatus as claimed in any preceding claim, wherein the grinding means comprises a substantially cylindrical grinding wheel.

11. An apparatus as claimed in any preceding claim, wherein the grinding means is rotatable by way of a variable speed motor.

12. An apparatus as claimed in any preceding claim and including means pivotably mounted relative to the support for applying a hard metal carbide tip to a tooth of the saw blade and means for securing the tip to the tooth.

13. An apparatus as claimed in claim 12, wherein the pivotably mounted means comprises a plate having a recess formed therein for receiving the tip.

14. An apparatus as claimed in claim 12 or 13, wherein the pivotable means is biased so as to urge the tip against the tooth.

15. An apparatus as claimed in any one of claims 12 to 14, wherein the tip is secured to the tooth by a high frequency welder.

16. An apparatus as claimed in any one of claims 12 to 14, wherein the tip is secured to the tooth by a resistance welder.

17. An apparatus as claimed in any one of claims 12 to 14, wherein the tip is secured to the tooth by a gas torch.

18. An apparatus as claimed in claim 15,16 or 17, wherein the welder or torch is movable towards and away from the tip and pivotable about one or more axes.

19. An apparatus for shaping and/or sharpening saw blades substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.