CA1127938A

CA1127938A - Reversible removable tip for sawtooth

Info

Publication number: CA1127938A
Application number: CA352,193A
Authority: CA
Inventors: Derek A.G. Silver; Grant Macfarlane
Original assignee: Spear and Jackson Canada Ltd
Current assignee: Spear and Jackson Canada Ltd
Priority date: 1980-05-16
Filing date: 1980-05-16
Publication date: 1982-07-20

Abstract

ABSTRACT OF THE DISCLOSURE
This invention is directed to an insertable tooth for saw blades that has a hardened cutting tip which can be inverted or reversed to expose a fresh cutting edge, thereby doubling the life of the cutting tip. The cutting tip, which is used in association with a tooth that can be inserted into the periphery of a saw body, comprises:
(a) a first sharp cutting edge located on one side of the tip;
(b) a second sharp cutting edge located on another side of the tip; and (c) means for securing the tip to the tooth, which means is functional regardless of whether the first or the second cutting edge of the tip is placed in position on the tooth for cutting use.

Description

~Z7938 FIELD OF THE INVENTION
This invention is directed to an insertable tooth for a toothed wood cutting saw blade. More particularly, the invention is directed to an insertable tooth for such blades that has a hardened cutting tip which can be inverted or reversed to expose a fresh cutting edge, thereby doubling the life of the cutting tip.
BACKGROUND OF THE INVENTIO~
Insertable teeth have been used in wood cutting saw blades for many years. One advantage of this arrangement is that the teeth can be made of a hardened metal suitable for wood cutting while the tooth carrier, such as a disc, can be made of a metal suitable for withstanding stresses encountered in high speed service. Another advantage is that the teeth can be removed for sharpening, or can be replaced, without handling or replacing the entire saw blade.
Insertable teeth have typically been generally elongated plate-like members constructed of tool steel.
In circular saws, they are set around the circumference of a disc-shaped carrier and ex-tend in a radial direction from the axis of the dlsc. In use, the disc and peripheral teeth rotate axially about the axis of the disc.
The insertable teeth are typically beveled to form a cutting edge in one plane and are alternately arranged and slightly offset so as to cut a kerf in the wood somewhat wider than the lateral-thickness of the insertable tooth and the disc. This prevents ~amhina ~27938 of the teeth and disc in the wood. In some embodiments, the offset arrangement of each tooth is caused by the presence of grooves on the leading and following edges of each insert. These grooves cooperate with beveled members that are present in slots found in the disc-shaped carrier to receive the insertable tooth.
One or more apertures in the insertable teeth and disc are also typically provided to enable the insertion of rivets to hold the inserted tooth in place in the disc carrier.
One continuing problem with the insertable teeth disclosed in the prior art is that they have tended to become dull when used for only a few hours as slashers for paper pulp manufacture. This has caused high maintenance costs incurred in removing and sharpening the insertable teeth.
Canadian Patent No. 1,051,321, granted March 27, 1979 to Jack K. Reed, discloses and claims a design of insertable tooth for slasher service that allegedly can be used continuously for periods of up to sixty days with no noticeable decline in performance.
The cost of producing each insertable tooth, according to Canadian Patent No. 1,051,321, is said to he considerably more than in the prior art but the extended life of the teeth and the savings experienced from reduced down time and upkeep is said to result in an overall lowering Gf costs.
The insertable tooth design disclosed in Canadian Patent No. 1,051,32, w'nich is also said to significantl~ reduce frictivnal heat generation ~Z7938 problems, comprises a flat elongated plate of steel of even thickness having a rounded base, substantially parallel leading and following edges with a V-shaped groove extending along a lower major portion of the leading and following edges engaging the edges of the slots, and a planar top angularly extending from an inner point on the following edge of the tooth toward an outer point near the leading edge of the tooth, with the inner and outer points being radially outside of the outer edge of the disc. A notch at the outer point receives a cutting blade in the form of a cubic trapezoid, the base of which is arranged ahead of the leading edge substantially parallel to a radial line extending from the center of the disc, and perpendicular to the plane of the disc. The width of the base is greater than the thickness of the plate and the sides of the blade are relieved from the base at an angle. The upper surface of the blade is arranged essentially co-planarly with, but radially outwardly from the planar top, with the blade being retained in the notch by brazing the blade to the plate.
No one of the insertable teeth of the prior art as discussed above is believed to address itself to solving two fundamental continuing problems in the field of woodcutting. One problem is that only one edge of an expensive hardened cutting tip, such as that disclosed in Canadian Patent No. 1,051,321, is used for cutting purposes. Either the tip is discarded when the edge becomes dull or the tip on the one edge can be sharpened only a fixed number of times before the tip is 1~27938 discarded.
Another shortcoming is that the hardened tip is brazed in place and it is not possible to remove the tip without heating it to melt the brazing. m is is time consuming and troublesome.
SUMMARY OF THE INVE~TIO~
We have invented an insertable tooth having a hardened tip which has a sharpenable cutting surface on both the top and bottom of the tip and therefore can be used for cutting purposes on either of the two sides merely by inverting the tip. While the new tip can be used with brazing, it can also be used without brazing and can be replaced without applying heat to the tip to melt the brazing.
An advantage of the tip is that it can be discarded after both cutting edges have been used to full extent, and a new double cutting edge tip can be inserted in its place. The double cutting edge permits double the life that can be obtained from one tip. With the discardable tip, no maintenance or sharpening is required. Maintenance in the field is often difficult to conduct and the double life permitted by the invention reduces maintenance accordingly.
m e top and bottom halves of the hardened tip of the invention may be symmetrical with one another.
The hardened tip is either of a generally symmetrical trapezoidal shape for cross-cut use, or a rectangle, for rip saw use, when viewed from the front and a generally symmetrical pentagonal shape when viewed from the top.
The top and bottom surfaces of the tip have sharp ~127938 cutting edges. The front surface of the tip is perpendicular in a vertical direction but is angled laterally to one side in a horizontal direction, for cross-cut use, or is square, when the tip is used for ripping wood. The rear side of the tip in either case protrudes to form an inverted V edge that fits closely in a similarily angled vertically extending V-shaped groove located in the front top edge of the body that forms the insertable tooth. The tip, regardless of whether it has an angled or square cutting edge, can be inverted top to bottom in the V-shaped groove to enable either the top or bottom edge of the tip to be used for cutting purposes. The tip is held in place in the V-shaped groove of the tooth body by brazing or by a suitable securing mechanism such as a set screw, or an eccentric bearing pin.
The invention is directed to a cutting tip for use in association with a tooth that can be inserted into the periphery of a saw body comprising:
(a) a first sharp cutting edge located on one side of the tip;
(b) a second sharp cutting edge located on another side of the tip; and (c) means for securing the tip to the tooth, which means is functional regardless of whether the first or the second cutting edge of the tip is placed in position on the tooth for cutting use.
In the cutting tip according to the invention, the securing means may be a V-shaped projection at the il27938 rear face of the tip that cooperates with and fits in a V-shaped groove cut in the edge of the tooth and the V-shaped projection of the tip is secured in place in the V-shaped groove of the tooth by a suitable securing mechanism.
The tip securing means may be any suitable means or technique such as silver brazing, a set screw or an eccentric bearing means.
The invention is directed to a cutting tip for use in association with a tooth that can be inserted into the periphery of a saw body comprising:
(a) a sharp cutting edge located at the top of the tip;
(b) a sharp cutting edge located at the bottom of the tip;
(c) a vertically extending front face angled laterally and horizontally to one side of the tip, when viewed from above or below;
(d) two parallel opposed side surfaces, each intersecting at its front with the respective sides of the front face; and (e) a protruding rear face made up of two parallel intersecting vertically extending planes which when viewed from above or below form a V configuration.
A cutting tip according to the invention wherein the top half of the tip is a symmetrical reflection of the bottom half of the cutting tip.
A cutting tip according to the invention wherein the front face of the cutting tip is planar and when viewed from the front is a symmetrical trapezoid.
A cutting tip according to the invention wherein a hole with a countersunk rim is provided in the front face of the cutting tip.
A cutting tip according to the invention wherein the V-shaped rear face of the cutting tip is mounted in a congruent V-shaped groove cut in the front edge of a saw tooth body which supports the tip.
The tip may be secured to the saw tooth body by means of a removable countersunk set screw.
DRAWINGS
In the drawings:
FIGURE 1 illustrates a front elevation view of an insertable tooth with the invertable hardened tip;
FIGURE 2 illustrates a side elevation view of an insertable tooth with the invertable hardened tip;
FIGURE 3 illustrates a top elevation view of an insertable tooth with the invertable hardened tip;
FIGURE 4 illustrates a front elevation view of an alternative embodiment of the insertable tooth with the invertable removable hardened tip;
FIGURE 5 illustrates a side elevation view of an alternative embodiment of the insertable tooth with the invertable removable hardened tip;
FIGURE 6 illustrates a top elevation view of an alternative embodiment of the insertable tooth with the invertable removable hardened tip FIGURE 7 is a front elevation enlarged view of the invertable removable hardened tip;
FIGURE ~ is a side elevation enlarged view of the invertable removable hardened tip;
FIGURE 9 is a top elevation enlarged view of the invertable removable hardened tip; and FIGURE 10 is a side elevation detailed view of a carrier body and three insertable teeth, two of which are in place in the carrier body.
FIGURE 11 illustrates a front elevation view of an alternative embodiment of an insertable tooth with the invertable hardened tip;
FIGURE 12 illustrates a side elevation view of an alternative embodiment of an insertable tooth with the invertable hardened tip;
FIGURE 13 illustrates a top elevation view of an alternative embodiment of an insertable tooth with the invertable hardened tip;
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGURE 1, the insertable tooth body 1 is constructed so that it is relatively thin in cross-section and has around three edges of its periphery a V-shaped groove 2. An invertable hardened tip 3 is mounted at the top front edge of the tooth body 1. Approximately mid-point at the front edge of the tooth body 1 is located a rivet recess 4. A drive hole 5 is punched through the width of the lower portion of the tooth body 1. The hardened tip 3 has a first cutting edge 6 at the front of its top surface, and a second cutting edge 7 at the front of its bottom surface.
Referring to FIGURE 2, which is a side elevation view of the tooth body 1, it can be seen that 1127~38 the hardened tip 3 fits at the top front edge of the tooth body 1, and the rear face of the hardened tip 3 fits in V-shaped groove 2 of the tooth body 1. The top surface 8 of the tooth body 1 slants downwardly and rearwardly away from the hardened tip 3. Accordingly, the top front surface of the hardened tip 3, which is the cutting edge 6, stands in relief of the overall tooth body 1.
Referring to FIGURE 3, it can be seen that the rear face 9 of the hardened tip 3 protrudes in a V-shape at an angle equivalent to the angle of the V
groove 2 of the tooth body 1 thereby enabling the rear face 9 of hardened tip 3 to fit securely with tooth body 1. The hardened tip 3 is normally held in place in the V-shaped groove 2 by means of silver brazing.
When cutting edge 6 of hardened tip 3 becomes dull with use, tip 3 can be inverted by melting the silver brazing and mounting the hardened tip 3 so that the second cutting edge 7 takes the place of first cutting edge 6 and becomes the active cutting edge of the hardened tip 3. The inverted tip 3 is then re-brazed in place in groove 2.
The front surface of tip 3, as seen in FIGURE 3, is angled laterally to one side in a horizontal direction. Referring to FIGURE 4, which shows a front elevation view of the tooth body 1, similar to that shown in FIGURE 1 discussed previously, it can be seen that in place of silver brazing, the hardened tip 3 is held in place by means of a set screw 10. ~e set screw 10 is countersunk in the front ~279;~8 face of the hardened tip 3 and penetrates into the front top portion of tooth body 1. The construction of hardened tip 3, with the countersunk hole for receiving set screw 10, is discussed in more detail below in association with FIGURES 7, 8 and 9.
FIGURES 5 and 6 show detailed side and top elevation views respectively of the tooth body 1 shown and discussed in association with FIGURE 4, and showing further detail of how hardened tip 3 is held in place at the top of tooth body 1 by set screw 10.
Referring to FIGURES 7, 8 and 9, which show in detail the construction of the hardened tip 3, together with a countersunk hole for receiving set screw 10, it can be seen that the construction of the hardened tip 3 is such that the top half is a symmetrical reflection of the lower half. This symmetrical construction permits the hardened tip 3 to be inverted on the tooth body 1 when first cutting edge 6 becomes dull and sharp cutting edge 7 by inversion takes the place of dull cutting edge 6.
Referring to FIGURE 9, it can be seen in detail that the front surface of hardened tip 3 is angled laterally in a horizontal direction, which provides a cutting face which is angled to the cutting direction that the hardened tip 3 travels (downwardly as shown in FIGURE 9), rather than presenting a face which is square to the direction of travel of the cuttiny edge. ~his construction improves the cutting ability of the hardened tip 3 in wood cross-cutting applications for which this design is intended.

1~793B

It will be noted that when hardened tip 3 is inverted so that second cutting edge 7 takes the place of first cutting edge 6 at the top of the tooth body 1, the angle of the front face of the hardened tip 3 is reversed. However, the same thing occurs to the other inverted hardened tips 3 carried on other saw tooth bodies 1 mounted on the same saw, and accordingly, cutting action for the various tips in series is maintained. It will also be noted that the angle of the front face of the hardened tip 3 on successive tips can be set in an alternating pattern if that is required.
It will also be noted in FIGURE 9 that the first side cutting edge 13 and the second side cutting edge 14 are formed so that they face one another in parallel and are perpendicular to the direction of travel of the hardened tip 3 when the cutting tips 3 are actively cutting wood. The lateral distance between cutting edges 13 and 14 determines the width of kerf that is cut in the wood.
FIGURE 9 also illustrates first rear face 15 and second rear face 16 which are at right angles to each other and correspond in right angle to the angle of V-shaped groove 2 in the tooth body 1.
Referring to FIGURE 10, this drawing illustrates in detail how two insertable tooth bodies 1 (shown at the right) fit with the overall saw plate (tooth carrier) 17. Two securing rivets 18 hold the two tooth bodies 1 in place in the saw plate 17. Each tooth body 1 can be separated from its appropriate slot in saw plate 17 by removing rivet 18, as shown at the left :~27938 side of FIGURE 10, whereby a third tooth body 1 is shown pulled upwardly from its pocket (receiving opening) in saw plate 17. The pocket has formed therein a rivet hole 19, which, in combination with rivet recess 4 in the tooth body 1, cooperate to receive the rivet 18 when it is inserted in place. The tooth body receiving opening in saw plate 17 has around its rim a V-shaped bevelled edge which is machined to fit dimensionally with the groove 2 in tooth body 1. Drive hole 5 is useful for enabling the insertion therein of a suitable object so that a good grip can be obtained on tooth body 1 and it can be driven downwardly or pulled upwardly to insert it in or remove it from the receptacle in saw plate 17.
Referring to FIGURE 11, which illustrates an insertable tooth that has particular application to wood ripping applications, that is, cutting wood along the grain, rather than across the grain, the insertable tooth body 21 is constructed in the same manner as for the cross-cutting teeth so that it is relatively thin in cross-section and has around three edges of its periphery a V-shaped groove 22. An invertable hardened tip 23 is mounted at the top front edge of the tooth body 21. Approximately mid-point at the front edge of the tooth body 21 is located a rivet recess 24. A drive hole 25 is punched through the width of the lower portion of the tooth body 21. The hardened tip 23 has a first cutting edge 26 at the front of its top surface, and a second cutting edge 27 at the front of its bottom surface.

~27938 Referring to FIGURE 12, which is a side elevation view of the tooth body 21, it can be seen that the hardened tip 23 fits at the top front ede of the tooth body 21, and the rear face of the hardened tip 23 fits in V-shaped groove 22 of the tooth body 21. The top surface 28 of the tooth body 21 slants downwardly and rearwardly away from the hardened tip 23.
Accordingly, the top front surface of the hardened tip 23, which is the cutting edge 26, stands in relief of the overall tooth body 21.
Referring to FIGURE 13, it can be seen that the rear face 29 of the hardened tip 23 protrudes in a V-shape at an angle equivalent to the angle of the V
groove 22 of the tooth body 21 thereby enabling the rear face 29 of hardened tip 23 to fit securely with tooth body 21. The hardened tip 23 is normally held in place in the V-shaped groove 22 by means of silver brazing.
When cutting edge 26 of hardened tip 23 becomes dull with use, tip 23 can be inverted by melting the silver brazing and mounting the hardened tip 23 so that the second cutting edge 27 takes the place of first cutting edge 26 and becomes the active cutting edge of the hardened tip 23. The inverted tip 23 is then re-brazed in place in groove 22. Other securing means such as a set screw, or an eccentric bearing pin, can be used.
The front surface of tip 23, as seen in FIGURE
13, is square to the direction of travel of the tip 23, when in wood cutting use. Similarly, the top cutting edge 26 and bottom cutting edge 27 are square cut, as shown in FIGIJRE 11.

~127938 As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A cutting tip for use in association with a tooth that can be inserted into the periphery of a saw body comprising:
(a) a first sharp cutting edge located on one side of the tip;
(b) a second sharp cutting edge located on another side of the tip; and (c) means for securing the tip to the tooth, which means is functional regardless of whether the first or the second cutting edge of the tip is placed in position on the tooth for cutting use.

2. A cutting tip according to Claim 1 wherein the securing means is a V-shaped projection at the rear face of the tip that cooperates with and fits in a V-shaped groove cut in the edge of the tooth and the V-shaped projection of the tip is secured in place in the V-shaped groove of the tooth.

3. A cutting tip according to Claim 2 wherein the securing means is silver brazing.

4. A cutting tip according to Claim 2 wherein the securing means is a removable set screw.

5. A cutting tip according to Claim 2 wherein the securing means is an eccentric bearing pin.

6. A cutting tip according to Claim 3, 4 or 5 wherein the first cutting edge is at the top of the tip and the second cutting edge is at the bottom of the tip, - Page 1 of Claims -and a line drawn between the first and second cutting edges is parallel with the V-shaped groove of the tooth.

7. A cutting tip for use in association with a tooth that can be inserted into the periphery of a saw body comprising:
(a) a first sharp cutting edge located at the top of the tip;
(b) a second sharp cutting edge located at the bottom of the tip; and (c) a protruding rear face made up of two parallel intersecting vertically extending planes which form a V
configuration, when viewed from above or below, the line of intersection of the planes being parallel with a line drawn between the first and second cutting edges.

8. A cutting tip according to Claim 7 wherein the top half of the tip is a symmetrical reflection of the bottom half of the cutting tip.

9. A cutting tip according to Claim 8 wherein the front face of the cutting tip is planar and when viewed from the front is a symmetrical trapezoid.

10. A cutting tip according to Claim 7, 8 or 9 wherein a hole with a countersunk rim is drilled through the front face of the cutting tip.

11. A cutting tip according to Claim 7, 8 or 9 wherein the V-shaped rear face of the cutting tip is mounted and secured in a congruent V-shaped groove cut - Page 2 of Claims -in the front edge of a saw tooth body which supports the tip.

12. A cutting tip according to Claim 7, 8 or 9 wherein the rear inverted V-shaped face of the cutting tip fits in a corresponding V-shaped groove of a tooth body, and the tip is secured to the tooth body by means of silver brazing, a countersunk set screw, or an eccentric bearing pin.

13. A cutting tip according to Claim 7 wherein the tip has a front face which is vertical and angled transversely and horizontally when viewed from above or below.

14. A cutting tip according to Claim 7 wherein the tip has a front face which is vertical and is square with the direction of cut of the first and second cutting edges.

15. A cutting tip according to Claim 13 or 14 wherein the top half of the tip is a symmetrical reflection of the bottom half of the cutting tip.

16. A cutting tip according to Claim 13 wherein the front face of the cutting tip is planar and when viewed from the front is a symmetrical trapezoid.

17. A cutting tip according to Claim 14 wherein the front face of the cutting tip is planar and when viewed from the front is rectangular.

18. A cutting tip according to Claim 13, 14 or 16 wherein the V-shaped rear face of the cutting tip is mounted and secured in a congruent V-shaped groove cut in the front edge of a saw tooth body which supports the tip.

- Page 3 of Claims -

19. A cutting tip according to Claim 13, 14 or 16 wherein the rear inverted V-shaped face of the cutting tip fits in a corresponding V-shaped groove of a tooth body, and the tip is secured to the tooth body by means of silver brazing, a countersunk set screw or an eccentric bearing pin.

- Page 4 of Claims -