WO1985001242A1

WO1985001242A1 - Saw blade or blank having self plugging stress relief means

Info

Publication number: WO1985001242A1
Application number: PCT/US1984/001440
Authority: WO
Inventors: Connell A. Wittkopp
Original assignee: The Peerless Saw Company
Priority date: 1983-09-09
Filing date: 1984-09-10
Publication date: 1985-03-28
Also published as: EP0155314B1; EP0155314A4; DE3483262D1; EP0155314A1

Abstract

In the manufacture of saw blades or saw blanks (1), radial slots terminating in a plugged circular stress hole are well known. The manufacture of such blades or blanks (1) requires multiple machining steps and separate plug elements (6). This invention provides circular saw blades or blanks (1) including a radial stress relief slot (12) in which radial stress of the slot is dissipated in a "self plugged" slot base having a curvilinear configuration (11, 13, 14) extending from the slot (12). The slot (12) does not depend upon the introduction of foreign media (6) for noise suppressing characteristics. A method of making the same is also described.

Description

SAW BLADE OR BLANK HAVING SELF PLUGGING STRESS RELIEF MEANS

FIELD OF THE INVENTION

This invention relates to improved circular saw blades and blanks from which saw blades are made.

BACKGROUND

The circular saw blade is well known. In the prior art, radial edge slots at the outer circumference of the blade have long been used to allow expansion in order to relieve thermal and other stresses. The slots also improve dynamic stability as the critical buckling speed of the saw increases. Slots have been conventionally machined into the blade during the manufacturing process. In certain instances, a radial slot extending in a saw blade terminates in a circular hole in the blade, which hole in turn may be plugged with a separate solid such as copper or another solid material of the same or different media. In this manner, the radial stresses created by a straight slot in the blade are considered to terminate and/or dissipate at the circular base hole at the end of the slot; and the plug inserted in the hole may reduce blade noise.

In this respect, while it is known that a rotating saw blade will create noise, conflicting reports exist regarding the effect of slots on radiated noise; and the basic noise mechanism associated with slots is yet to _be scientifically understood. Similarly, it is known that

O PI &?NAT\ slot configurations affect damping, noise, vibration, stability and tensioning of the saw blade while in use; however, the complex relationships and interrelationships of these parameters to various measures of saw performance and different saw geometries are likewise yet to be under¬ stood.

OBJECTS OF^'THE INVENTION t is an object of this invention to provide a stress relieving means in a circular saw blade including a radial edge slot which essentially terminates in a further intrinsically cut stress stop which may also act as a noise suppressant. Thus, an effectively "self-plugging" stress relieved saw blade is provided. It is a further object to provide a slotted blade which includes a self plugged slot which may be produced in a single continuous machining operation, thereby avoiding the separate steps of slotting, drilling, plugging and/or punching which are conventional manufacturing steps in prior art blades.

BRIEF DESCRIPTIONS OF- THE DRAWINGS

Figure 1 shows a conventional "prior art" blade for purposes of comparison with Figure 2 which shows a saw blade in accord with the invention. Figure 2A shows a detail of the slot of the blade of Figure 2 and Figure 2B, 2C and 2D illustrate alternative slot configurations with respect to a blade or blade segment. DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the blade of Figure 1 , there is shown a circular metal disc 1 having a plurality of saw teeth 2 on the outer circumference thereof and a center mounting eye 3. In this conventional blade, a plurality of regularly spaced milled stress relief radial edge slots 4, are typically provided extending from the outer circumference of the blade ' inwardly towards the eye and terminating in a round base hole 5 between the blade eye and outer circumference. The base hole is separately plugged with material such as a copper plug 6 which can be permanently fitted into the hole. Multiple plugged slots are evenly distributed around the circumference, such as the four slots shown spaced at 90° separations on the saw blade. Other stress relief configurations varying the dis¬ tribution, spacing, number and depth of slot are also possible. Similarly, while saw blades are made in many sizes, a representative dimension, for illustration pur¬ poses in connection with this application, for a blade 12 inches (nominal) in diameter includes a mounting eye hole of 0.625 inch, a slot width of 0.065 inch extending_, 1.062 inch radially into the. blade, terminating in a copper plugged hole 0.25 inch in diameter. The appropriate depth of the slot into the radius of the blade from the outer edge and the corresponding diameter of the base relief hole are dependent upon blade diameter and suitable dimensions are known to those skilled in the art. In contrast with the conventional blade shown in Figure 1, a blade of the invention is shown at Figure 2. The blade is essentially equivalent in utility and exhibits performance characteristics comparable to the blade of Figure 1, but includes a radial relief slot 10 which terminates in a further, "self-plugging, " stress stop, 11. This saw blade is equivalent in performance to a con¬ ventionally machined blade having a linear stress relief slot, terminating in a base relief hole plugged with a separate material. In the example of Figure 2 , a con¬ tinuous cut of essentially uniform thickness is made through the blade, first in an extended radial line beginning at the outer circumference of the blade, portion 12 of the slot, and extending inwardly. At the end of the linear portion, the cut continues in an essentially circular cut portion 13 which terminates in an inward spiral segment 14 which has a considerably smaller radius of curvature than the first circular cut segment. In its most general description, the slot consists of a con¬ tinuous, stress relieving, essentially radial cut through the thickness of the blade extending inwardly from the outer circumference of the blade and terminating in an intrinsic stress stop, which dissipates radial stresses induced by the slot and which also acts as a sound sup¬ pressant without the introduction of foreign material such as a plug into the body of the blade. In Figure 2 the intrinsic stress stop extends in a cut circular segment having a radius essentially beginning at the end of the inwardly extending linear radial slot and continues to an inwardly turning spiral which preferably terminates at a point along the directional line of the radial slot. While references are made to the "beginning" and "terminating" points of the continuous cut, it is evident that these terms are relative positions and it is apparent that a line "begins" or "terminates" at either end depending upon selection of a first reference point.

In the example for a 12 inch blade, the continuous self plugging slot includes a linear cut extending 1.062 inch from the circumference, at which point a nominal 0.25 inch diameter circular cut is begun, preferably after a radial turn in the line of cutting, and continued for approximately 270° before the inwardly turning spiral segment of reduced diameter (approximately .125 inch) continues another 180° to the termination of the cut, essentially at the center of the .25 inch diameter cut, and along the linear directional line of the straight radial cut. The width of the cut into the saw body is approximately .005-.006 inch. The continuous cut into the saw blade body may be made in various manners known to those of skill in the machine tool art, such as by a fine mechanical saw, EDM (electrical discharge machine) or suitably controlled industrial laser. Thus, a radial slot terminating in a spiral is provided. A figurative des¬ cription of the slot shown in Figure 2 allows comparison of the self-plugging slot with the appearance of a question mark (?) extending into the blade. The slot need not be exactly radial and may be either positively or negatively slanted with respect to a true blade radius. Other geometric configurations may also pro¬ vide a stress relieving, self plugging slot and will be evident to those of skill in the art familiar with stress relief means used in conventional saws in view of the disclosure of this application. Thus, as shown in Figure 2B positive, or, as shown in Figure 2C, negative hook angles for the slot may be employed as shown in Figure 2D, the slot may be straight or curved; slots may be evenly or unevenly distributed around the circumference of the blade; and the depth of the slots extending from the circumference into the blade may similarly be equal or unequal with respect to multi-slotted blades; and differing numbers of slots per blade may be used. In instances of such con¬ figurations, the self-plugged stress relief slots of the invention will include an essentially continuous stress relief "slot" , extending from the blade circumference which terminates in a separately configured "stress stop" in the body of the blade between the circumference and blade eye. Thus, a linear slot plus stress stop is provided. Both the slot and the. stop are formed from the same continuous cut extending from the outer circumference of the blade, and the stop is not dependent upon the insertion of a plug or other foreign .media for the .purpose of noise suppression. In this regard, a stress stop having a curvilinear or circular segment provides a preferred stress stopping or dissipating means consistent with the geometric con¬ figuration of a continuous cut. In this connection, it is, however, apparent that the thickness of the continuous cut which combines a stress relief slot with an intrinsic a stress stop should be uniform and not exceed a dimension in which the structural integrity of the combination of the stress relief slot and stress stop, as provided by a continuous cut, is adversely affected.

The cut should be relatively narrow when compared to the dimensions of the slot and stop. In the blade of the example, the dimension of the width of the cut, approximately .005 inch, represents a minor proportion, 2% , of the diameter, .25 inch, of the beginning circular spiral segment, and a similar minor proportion, 4%, of the con¬ cluding inner segment of the spiral which is .125 inch in diameter.- These proportions may vary, and are not by themselves critical; however, as a general rule the width of the self plugging cut should be of a thickness which is only a minor proportion of the circular spiral if in fact a spiral configuration is used. It should be evident to those of skill in the art that the term "minor" in the context of a particular saw blade will depend upon geometric proportions of the blade itself as well as of the configuration of the continuous cut which forms the stress relieved, self plugged slot. In a similar manner, a saw blade comprising an "unfinished" saw blank (i.e. , unsharpened, or to which cutting teeth will be applied) is likewise an article of commerce to which the invention is applicable and which is not excluded from the scope of the claims.

ζ_TREAι _QMPl__

Claims

WHAT IS CLAIMED IS:

1. A circular saw blade including an inwardly directed stress relieving slot beginning at the outer circumference of the blade, extending into the blade, and terminating in an intrinsically cut stress stop including a curvilinear cut segment in the blade between the blade eye and the outer circumference of the blade, said slot and intrinsically cut stress stop consisting of the same relatively narrow continuous cut of essentially uniform width made through the blade.

2. The blade of claim 1 in which the intrinsically cut stress stop includes a segment which is circularly shaped.

3. The blade of claim 2 in which the con iguration of the circular portion of the stress stop continues in an essentially spiral configuration.

4. The blade of claim 1 in which the relatively narrow uniform thickness of the continuous cut forming the radial slot and the terminating stress stop is a minor proportion of the nominal diameter of the terminating curvilinear portion of the stress stop.

5. The blade of claim 1 including a straight radial shot.

6. The blade of claim 1 including a slot having a positive hook angle.

7. The blade of claim 1 including a slot having a negative hook angle.

8. The blade of claim 1 including a plurality of slots beginning at the outer circumference of the blade.

9. The blade of claim 8 in which the slots are equally spaced around the circumference of the blade.

10. The blade of claim 8 in which the slots are unequally spaced around the circumference of the blade.

11. The blade of claim 8 in which the slots are each of the same depth extending into the body of the blade from the circumference.

12. The blade of claim 8 in which slots of differing depths extending into the body of the blade from the circumference are distributed around the circumference of the blade.

13. The blade of claim 8 having a plurality of equally spaced stress relieving radial slots each terminating in curvilinear, intrinsically cut stress stops.

14. A circular saw blank including an inwardly directed stress relieving slot beginning at the outer cir¬ cumference of the blank, extending into the blank and terminating in an intrinsically cut stress stop including a curvilinear cut segment in the blank between the blank eye and the outer circumference of the blank, said radial slot and intrinsically cut stress stop consisting of the same relatively narrow continuous cut of essentially uniform thickness made through the blank.

15. The blank of claim 14 in which the intrinsically cut stress stop includes a segment which is circularly shaped.

-9-

16. The blank of claim 15 in which the configuration of the circular portion of the stress stop continues in an essentially spiral configuration.

17. The blank of claim 14 in which the relatively narrow uniform thickness of the continuous cut forming a radial slot and the terminating stress stop is a minor proportion of the nominal diameter of the terminating curvilinear portion of the stress stop.

18. The blank of claim 14 including a straight radial slot.

19. The blank of claim 14 including a slot having a positive hook angle.

20. The blank of claim 14 including a slot having a negative hook angle.

21. The blank of claim 14 including a plurality of slots beginning at the outer circumference of the blank.

22. The blank of claim 21 in which the slots are equally spaced around the circumference of the blank.

23. The blank of claim 22 in which the slots are unequally spaced around the circumference of the blank.

24. The blank of claim 21 in which the slots are each of the same depth extending into the body of the blank from the circumference.

25. The blank of claim 21 in which slots of differing depths extending into the body of the blank from the circumference are distributed around the circumference of the blank.

26. The blank of claim 14 having a plurality of equally spaced stress relieving radial - slots each terminating in circulinear, intrinsically cut stress stops.

27. A method of producing a noise suppressed stress relieved slot in a circular saw blade or saw blank con¬ sisting of, in a continuous operation; cutting a relatively narrow essentially radial slot into the blade or blank, which slot begins at the outer circumference and extends towards the blade or blank eye and terminating said slot in a continuingly cut essentially curvilinear segment in the area of the blade or blank between the outer circumference and eye, with a continuing cut into the blade or blank of essentially the same width as the slot, whereby "in a continuous linear cut in the saw blade or saw blank there is provided a first cut segment consisting of a stress relief slot which ends in a second curvilinear shaped stress stop.