USRE24660E - dessureau - Google Patents

Description

June 16, 1959 J -T DESSUREAU mp4,. Re. 24,660-

s'roms sums WIRE 0rig1 na'1 Filed July 22,1981

Servicoble Wearing one 20 FIG. 7 FIG. 8

INVENTORS JOSEPH -T. DESSUREAU 8r 7 JOHN B. DESSUREAU ATTORNEYS United States Patent Olfice Re. 24,660 Reissued June 16, 1959 STONE SAWING WIRE Joseph T. Dessureau and John B. Dessureau, Barre, Vt.

Original No. 2,856,914, dated October 21, 1958, Serial No. 673,226, July 22, 1957. Application for reissue February 20, 1959, Serial No. 794,791

2 Claims. (Cl. 125-21) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specifi cation; matter printed in italics indicates the additions made by reissue.

This machine relates to endless wire saws for stone cutting machines.

Stone cutting or sawing machines are now being extensively used to cut blocks of granite, marble and other stone by means of one or more endless abrasive wires or cables which pass over large pulleys on a carriage usually fed downwardly as the cut is made. To the cutting stretch of the wire saw is fed water and an abrasive material such as emery. These saws are usually composed of two or more strands of wire of hard drawn abrasive resistant steel or an alloy, that are twisted so that spiral channels or grooves are formed by the strands along the cable to carry the abrasive.

We have found that the fastest and most effective cutting action of the saw on the stone takes place when the outer peripheral areas of the strands that might contact the stone is large and the spiral channels between. the strands are sufficiently large in cross section to effectively carry the abrasive along the cut and feed the grit between such outer areas and the stone. The most ex tensively used cutting cables are formed of either two or three strands of round wire spirally twisted. When two round strands are used, the abrasive carrying channels are large but until the outer peripheral portions of the strands have been worn down to form larger wearing areas the cutting action of the cable is very slow. When the cable is composed of three round strands, the capacity of the abrasive carrying channels is substantially less, and before the serviceable wearing areas of the strands have been consumed the channels are too small to carry the abrasive along the cut and feed it between the stone and the outer peripheral areas of the strands.

In the type of fast sawing being done in the stone industry at the present time, on hard stone such as granite and marble, these cutting cables travel at a speed of about 4,500 feet per minute over pulleys or sheaves having a diameter of a few feet. Due to the rapid flexing of the cables it is, practically speaking, necessary to make them with a diameter of not more than A of an inch in order to prevent rapid crystallization of the metal of the strands. It is also important that the cables retain their tensile strength throughout their cutting life.

One object of the invention is to provide a stone sawing wire which has a considerably longer wearing life than the now known and used cables and which will cut eifectively at the beginning of its use and continue to cut at substantially the same rate until it is worn out, with the result that substantially more stone is cut per foot of wire,

Another object is to provide a stone sawing cable which not only has the above stated long and uniform fast cutting life but which also is easy to twist, will retain its twisted shape and will have sufiicient tensile strength throughout its useful life.

With the above and other objects and advantages in view, the invention resides in the novel combinations and arrangements of parts and the novel features of construction hereinafter described and claimed, and illustrated in the accompanying drawings which show the present preferred embodiment of the invention.

In the drawings:

Fig. 1 is a side view of a portion of our improved stone sawing wire or cable;

Fig. 2 is a cross sectional view on an enlarged scale;

Fig. 3 is a perspective view of an end portion of one of the two strands from which the cable is made;

Fig. 4 is a diagrammatic sectional view similar to Fig. 2 on a further enlarged scale;

Fig. 5 is a view of a portion of the old two strand cable made of round wires;

Fig. 6 is a cross section of Fig. 5;

Fig. 7 is a view showing the two strand round wire cable of Fig. 5 after it has been worn out; and

Fig. 8 is a cross section of Fig. 7.

The above stated objects of the invention are attained by making our improved cable of two strands of wire the cross sectional shape of which is half-round and half-square, the strands being spirally twisted together so that the central longitudinal portions of the halfround inner sides or faces of the two strands are in contact at the center of the cable and the square sides or faces form the outer peripheral portion of the cable. In the drawings the strands are designated generally by the numeral 10, and as seen in Fig. 3, each has flat parallel side walls 11 the inner portions of which merge into the half-round or semi-circular inner wall or face 12, and the outer portions of which terminate at the edges of the outer fiat wall or face 13 to form the halfsquare outer peripheral parts of the cable. While the outer wall 13 may be tangent to the circle struck on the radius of the curved inner wall 12, it is preferably spaced slightly away from that circle to provide a slightly greater amount of serviceable wearing material at the outer peripheral portion of the cable. That outer wall or face 13 is shown as fiat, but it may be slight-1y convex or concave crosswise of the strand. The preferred diameter of the cable formed by the two twisted strands is A of an inch so that the parallel side walls 11 of each strand are M; of an inch apart and the radius of the half-round portion 12 is A of an inch. When the two strands are twisted together the central points 14 of the curved or half-round inner sides of the two strands contact along the longitudinal axis of the cable; as seen in Fig. 2. That forms along the opposite sides of the strands spiral channels or grooves 15 which are large in cross sectional area and which extend inwardly to the axis of the cable. Thus the channels or spaces 15 have large abrasive carrying capacity and permit of the use of coarser abrasive grains for more economical operation of the saw. It is to be noted that the two strands have the same cross sectional shape and area, and since the wear is only at the peripheral portion of the cable, the tensile strength of one strand will continue to be equal to that of the other throughout the useful life of the cable.

The old two strand round wire cable has been shown in Figs. 5 through 9 to bring out the ditferences between it and our improved cable. In those views of the drawings the round strands are designated 20 and abrasive carrying channels 21. As indicated in the enlarged and diagrammatic view Fig. 9, when such a cable is first put into use the outermost surfaces of the strands contact with the stone at single points designated 22 because the strands are round. No effective cutting is done until the strands wear down to the dotted line circle 24 in Fig. 9. By the time the strands 20 have been worn down to the inner circle 25 the abrasive carrying channels 21 become so small (the portions of 21 withinthe circle 25) that the cables ceases to cut effectively and must be discarded. That worn out condition of the cable is shown in Figs. 7 and 8. Hence the really serviceable wearing area of each strand is the portion between the circles 24 35,, and it isdesignatedby the .arrowed lead lines and'the legend serviceable Wearing which corresponds to the circle 24 in Fig. 9. When the strands 10 have been worn down .tot he inner circle 25, the abrasive carrying channels are so small that effective cutting ceases and the cable must be discarded. In Fig. 4 the arrowed leadlines andthe legend -Serviceable Wearing Area indicate the cross sectional areas of the strands which .produces rapid and effective stone cutting. It is to be noted that these cross hatched portions of the strands in Fig. 4 are substantially larger than those in Fig. 9 By actual tests we have found that a cable constructed in accordance with our invention, willcut 30 percent more hard stone such as granite per foot of wire than the old two strand round wire cable of the same size; thatit will begin effective cutting from the very beginning of the use of the cable; that 'it will cut more uniformly throughout the useful life of the cable; and that it will have suificient tensile strength throughout its useful life to prevent breakage. It will be apparent that ;the reason our improved stone sawing cable does fast and eflective cutting from the beginning of its use and also substantially uniform fosti cutting throughout its useful life, is the use of two wires of substantially the geometrical shape shown having opposite their round inner portions enlarged outer portions which provide large masses of wear-taking metal, such as masses having a generally rectangular cross-sectional shape with a radial depth of at least one-half of the diameter of the wires and a transverse thickness or width of approximately the diameter of the wires, .the width being substantially the samethroughout the radial depth. Thus there is provided a cable, not only with relatively large and deep grit-carrying channels 15 but one with initially wide cutting surfaces 13 which continues 'to have substantially the same width of cutting surfaces from the beginning to the end of the useful life of the cable. The two strands are preferably made of hard drawn abrasive resistant steel and are twisted in .the manner of the prior art cables. While the cable may be formed in any suitable summer, we preferably either use the usual wire twisting machine with stationary dies of the same shape as the cross sectional shape of the strands, the latter being fed or drawn through the dies as they are drawn through the wire twisting machine, or by providing the twister head of the machine with pairs of opposed rollers having peripheral grooves shaped to the cross sectional shape of the strands to hold them with their halfround sides in contact during the :twisting operation. Thus the dies or rollers will hold the outer fiat portions of the strands to the outside of the twisted cable and will cause the half-round portions of the strands to contact at the center of the cable.

,4 At intervals the twist may be reversed, as is common practice. The two strands are easy to twist and provide the maximum size spiral channels which will take coarser grains of abrasive material and effectively feed it along the cut and between the stone and the outer peripheral areas of the strands. It will be understood that the ends of a. suitable length .of our improved flex l cable a e v s re e her 7 otherwise joined to form the endless saw.

From the foregoing, taken in connection with the accompanying drawing, it will be seen that novel and advantageous provision has been made for carrying out the objects of the invention, and while preferences have been disclosed, attention is invited to the possibility of making, variations Within the scope of the invention as claimed.

Weclaim:

1. A flexible stone sawing cable composed of two spirally twisted strands of half-round and halfsquare wire, the two strands being of the same cross sectional size and each having flat and parallel side faces, a semicircular inner face"which merges into said side faces and forms the half-round portion of the strand and a flat outer face at right angles to said side faces and forming with the latterthe half-square portion of the strand, said half-round portions of the strands being disposed at the inner part of the cable with the central portions of said semi cylindrical faces in bearing contact along the longitudinal axis of the cable, said half-square portions of the strands being disposed at the outer part of the cable with said flat outer faces of the strands forming the peripheral portion of the cable, whereby the cable will cause effective and rapid cutting from the beginning of ,its use and will continue to so cut at substantially the same rate throughout its useful life.

2. A flexible stone sawing cable composed of two spirally twisted strands of metal wire, the two strands being of the same cross sectional size and shape, each strand being transversely rounded along one side and having along its opposite side an enlarged wear-taking mass of metal of generally rectangular cross sectional shape, said rounded portions of the strands being disposed at the inner part of the cable and being in bearing contact along the longitudinal axis of the cable, said enlarged weartaking masses being disposed at the outer part of the cable and each having a radial depth of approximately one-half of the diameter of the wires and a width which is substantially equal to the diameter of the wires, the width or transverse thickness of said masses being approximately uniform throughout their radial depth, ,whergby relatively large grit-carrying channels will .be formed between the strands and the cable will cause eflective and rapid cutting from the beginning of its use and will continue to cut at substantially the same rate throughout its useful life.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS 2,123,619 "Wienholz July 12, 1938 2,45 1,383 DAvaucourt Oct. 12, 1948 2,876,761 Stevens Mar. 10, 1 959

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