US914303A - Dividing marble slabs. - Google Patents

Description

J. PBIRCE. DIVIDING MARBLE SLABS.

. APPLIOATION FILED JUNE 13 Patnted Mar. 2, 1909.

a sHEE'TssHEET 1.

INVHW OR 2- .WITNESSES:

J. RpPEIRCE.

DIVIDING MARBLE SLABS. APPLIOATION FILED JUNE13,1907.

Patented Mar.2,1909.

3 SHEETS-SHEET 2.

INVENTOR X44 2 Mk Alto/721% J. R. PEIRGE.=

'DIVIDIN G MARBLE SLABS' APPLICATION- FILED JUNI 113, 1907. v

Patented Main 2, 1909.

'3 SHEETS-SHEET a.

. Y. m M A 7 l/ WITNESSES:

UNITED STATES PATENT OFFICE.

JOHN ROYDEN PEIRGE, OF NEW YORK, N. Y., ASSIGNOR TO ROYDEN MARBLE MACHINERY- COMPANY, OF NEW YORK, N. Y., A. CORPORATION OF NEW JERSEY.

DIVIDING MARBLE SLABS.

Specification of Letters Patent.

Patented March 2, 1909.

Application filed June13, 1907. Serial No. 313,741.

analogous to the operation ,of a steel circularsaw with fixed teeth cutting through a hard wood plank. For this purpose a rapidly revolving thin wheel of carborundum agglom erated with a firm (preferably a vitrified) bond is used, the sharp particles of which act like the fixed teeth of a steel saw instead of being easily torn out of their matrix and acting as a loose sharp abradant. The bond is so hard. and strong as to facilitate the making of the wheel of minimum thickness. This possibility of using a very thin wheel not only cheapens the wheel and insures the removal of a com aratively insignificant quantity of marble, ut also calls for the expenditure of a minimum amount of power to drive it, and permits the wheel to be forced through the marble at a high speed for a given power. Notwithstanding its thinness, the wheel cannot be substantially deflected by the usually oblique irregularities of the marble even when forced through the marble at a rapid rate, and will make a straight out at comparatively high speed without stunning the marble or breaking the wheel. The rapid revolution of the carborundum wheel introduces a gyroscopic effect which immensely strengthens its resistance to lateral deflection, and permits the use of a wheel so thin (fivesixteenths 5/16 of an inch or less) in practice for wheels of 10, 12 or 14 inches diametcrthat it would be easily broken by a slight pressure when at rest. Such wheels, however, when in rotation, withstand a series of lateral blows or pressures such as are necessarily encountcrcdby reason of the lack of homogcncity of the marble, and the necessary imperfections of even the best machinery. The bonding of the particles so that they act as has. teeth instead of as a loose abradant, makes the wheel durably effective, the particles not being torn from their matrix before they have done approximately all the work which they are capable of doing, and have become so dulled that they are practically worthless.

The particular field of usefulness of the invention, namely, the dividing of comparatively thin slabs, makes possible the use of wheels of the smallest diameter and consequently of the highest efficiency and the greatest thinness. The diameter is neces-. sarily limitedby the impossibility of molding inte rally of large diameter, a wheel which shall be so thin. as to satisfy the commercial 4 requirements of low initial ex ense, low consumption of power and smal waste of marble, and the techincal requirement of sufficient lateral strength to revent deflection. Concerning the possibility of deflection, I have observed that the use of wheels with a soft; bond operating at commercially possible speeds, results in the cutting of a ine which is far from straight, and which would not be accepted by builders for the edges of wall facing slabs or the like. As such a wheel runs into an extra hard portion of the marble at a good speed, it is materially deflected out of a straight line; and it would require impracticably slow and careful feeding to be worked through the'marble in a substantially straight line, as well as resulting in a less sharp edge on the marble. The invention is also restricted to the use of a wheel of the materials and structure described.

Marble cutby this process is left with a clean sharp edge and a perfect arris. There is' little or no subsequent rubbing or polishing of the edge, such as is always necessary with An additional feature of great importancev is the flaring of the edge of the carborundum wheel. I have found that such flaring reduces the number of breakages of the coping wheels to a negligible point, whereas without such flaring the wheels are in danger of breaking more or less often. The exact reason Whyflaring 0f the edge should reduce the tendency of the wheel to break is not clear, especially as the flaring wheels used have their greatest thickness, their thickness at lofi the edge, no greater than the thickness of the flat wheels, and the material removed from the flared edge inward to the hub would panying drawings of apparatus for carry ng out the process of the invention.

seem to lessen their capability of resisting lateral pressures. Nevertheless the differpnce in this respect is clear and very much in avor of the flared wheels.

Further advantages in detail are referred to hereinafter in connection with the accom- Figures 1, 2 and. 3 are respectively a plan, side elevat on, and. cross section of an apparatus in whichthe cutting wheel is mounted underneath the slab; Fig. 4 is an enlarged detail in cross-section of the same machine; Fig. 5 is a longitudinal section of another type of machine in which the Wheel is mounted above the slab; Fig. 6 is an enlarged d'e-- tail in cross-section of the same. I

Referring to the embodiment of the invention illustrated, the marble slab A may be mounted upon a movable bed B having a slotted center through which projects upand need not be here described in further do tail. The wheel C in each case is carried upon a comparatively small shaft rotated rapidly in antifriction bearings, so as to secure maximum speed without the necessity for high pressure such as necessarily accompanics the use of'steel tools on marble. The wheels for example may be rotated at about 2,000 revolutions per minute, or a peripheral s eed of approximately a mile a minute.

i he wheels are preferably of 10, 12 or 14 inches diameter, the smallest diameter being the most efficient. As the diameter of the wheel is increased the area of contact with the marble increases, and the total pressure on the wheel necessary to secure a given unit pressure between the wheel and the marble, or to secure the desired penetration of the cutting edges into the marble, increases; and at the same time the lateral strength of the wheel to resist'such total pressure, decreases as its diameter is increased. The maximum thickness of the wheels which I use is about a half inch. For most work, wheels of fivesixteenths (5/16) of an inch in thickness will stand the strain satisfactorily, and in especially light work 1 have even used wheels of one-quarter of an inch in' thickness with success. The rate of feed of the .wheel longitu- 'dinall throughthe marble varies between wide 'mits byreason ofthe wide variations in the hardness and degree of uniformity en countered in marbles, and from other causes. Thejmachineswhich I have used are designed for speeds from six inches to: thirtys1x inches a mmute, and this range will cover most of the .cases arising in practice.

The material of the wheels is carborundum of a degree of coarseness depending upon various conditions. An increase in the coarseness pfthe grain increases up to a certain point the rapidity of cutting. On the other andthe grain must be so me as to permit of the molding of the wheel with a number of grains across 'its thickness, and this, with the thin wheels which are essential to success, restricts the size of the grains. Furthermore the finer grains have a supplementary advantage i leaving a better edge andarris than the coarser grains. I prefer for most classes of work to useapproxunately 10-grit or IO-mesh carborundum, that is to say carborundumwhose grains will pass through a sieve of 10 meshes tothe linear inch.

The wheels are formed by molding them in the usual way with a bond which must hold the particles of carborundum so firml that they out like the fixed teeth of the ord Iia steel saws used in sawing hard wood, are durabl efficient, so that they do substantially al their work while bound in to the Wheel. -This is very important in connection with the dividing of thin slabs, because after the particles are once torn out from their matrix, they can-remain in operative position, that is between the wheel and the marble, for only the briefest moment of time. In common stone sawing machines where-a steel or other flat non-toothed blade revolves or reci roe-ates in the groove in a thick stone bloc while a loose abradant is fed into the same groove with water, the abradant is held in cutting position between the blade and the stone for a substantial period of time; furthermore with such rooesses it is customary only to use abrat ants which become dulled much more ra idly than carborundum, sinceit is impossib le to assure the abradants being in the operative osition for a period of such length as would e necessary to utilize all the cutting power of carborundum. But for dividing slabs inthe manner contemplated by" the iresent invention, it is important to carry "the cutting particles lof carborundum within the matrix of the wheel during their-life so to J' speak that is to say, during the entire pfirio'd during which they are -0iliciently s a1 Tl ie bond is not only "such as to hold the teeth firmly,-but it is itself hard and strong, so that notwitlistandin the thinness of the wheel it cannot be su stantially deflected. In Fig. 1 there is indicated in dotted lines a portion G such as frequently occurs in marble, and which may be materially harder than the rest of the slab. The wheel may strike this hard portion'G at a ver slight angle, so that the tendency" to de set the wheel will be very great. Nevertheless the bond must be so hard and strong'as to prevent anydefiection which will be noticeable to the eye, otherwise the slab could not be laid on a wall with joints of the perfection which are demanded in practice. Furthermore such hard spaces G in the marble tend to break the wheel, but my experiments have shown that by the use of a hard bond, such foi' example as a vitrified bond, and by reason of the added strength due to the gyrosco ic action of the rapidly revolving wheel, may employ wheels of the dimensions stated in practically all classes of work.

In my efforts to provide an o erative machine with the very thin whee s which are essential to commercial success, I have found that with thin wheels of the style in the market (and previously used only for sharpening small tools and similar work), that is, having flat faces, the number of breakages in a Weeks running of the machine amounted to a substantial item of expense, this disadvantage however being insufficient to overcome the technical and commercial advantages of using a thin wheel. I have, however, succeeded in practically eliminating this disadvantage also by dishing the faces ofthe Wheels slightly, so that their edges flare as indicated in Figs. l and 6. This feature of construction while removing the last obstacle to commercial si'iccess of the wheels, adds practically nothing to their cost. In the ordinary manufacture of the wheels they are molded and then baked,

and theirfaces are afterward dressed to a plane. The dressing of the faces to the dished shape shown is no more expensive than the dressing of them to a flat surface, it being necessary only to feed the dresser progressively deeper into the face of the wheel as it moves toward the center thereof.

This feature of construction is claimed in a prior application for patent No. 260,792, led May 17, 1905, independently of the qualifications of the present invention. 3

For keeping marble as cool as possible and reducing the friction of the wheel, it is preferable to employ jets of water projected upon the edge and side faces of the wheel. Preferably the bond used is so hard that particles of carborundum cannot be torn out 'tiall which consists in cutting through it with a wheel of carboruno um rotating rapidly with slight pressure, said wheel having a diameter of approximately twelve inches, and being agglomerated with such a firm vitrified bond that the sharp particles out like fixed teeth, and the bond being so hard and strong that notwithstanding the thinness of the wheel it cannot be substantially deflected by the oblique irregularities of the marble while operating with a rapid feed, said wheel being approximately five-sixteenths of an inch thick at its edge and having its side. faces dished.

2. The process of dividing a marble slab which consists in cutting through it with a rapidly rotating wheel of carborundum, said wheel having a maximum thickness of not more than approximately half an inch, and being agglomerated with such a firm bond that the sharp particles cut like fixed teeth, and the bond being so hard and strong that notwithstanding the thinness of the wheel it-cannot be substantially deflected by the oblique irregularities of the marble while operating with a rapid feed.

3. The process of dividing a marble slab which consists in cutting through it with a rapidly revolving thin wheel composed of carborundum agglomerated with such a firm bond that the sharp particles out like fixed teeth, and the bond being so hard and strong that the wheel notwithstanding its thinness cannot be substantially deflected by the oblique irregularities of the marble while operating with a rapid feed.

'4. An apparatus for dividing a marble slab including a wheel composed of carborunslight pressure and for moving it through theslab, said wheel having a diameter of approximately twelve inches, and being agglomerated with such a firm vitrified bond that the sharp particles out like fixed teeth,

and the bond being so hard and strong that I the wheel notwithstanding its thinness cannot be substantially deflected by the oblique irregr-ilaritics of the marble while operatlng with a rapid feed, said wheel being a proxi- 1 mately five-sixteenths of an inch thic at its edge and having its side faces dished.

5. An apparatus for dividing a marble slab including a wheel composed of carborundum, and means for rotating it rapidly and for moving it through the slab, said wheel having a maximum thickness of approxi- 'matcly half an inch, and being agglomerated with such a firm bond that the sharp particles out like fixed teeth, the bond being so hard and strong-that notwithstanding the thinness of the wheel it cannot be substandeflccted by the oblique irregularities pf t c marble while operating with a rapid eed.

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6. An avparatus for dividing a marble {by the oblique irregularities of the marble 1Q slab inclu ing a thin Wheel composed of while operating Witharapid feed. carborundum, and means for rotating it In witness whereof, I have hereunto rapidly and for moving it through the slab, signed my name in the presence of two subthe carborundum being agglomerated with I scribing witnesses.

sucha firm bond that the sharp particles cut JOHN R0 YDEN PEl R CE. like fixed teeth, the bond being so hard and Vl-"itnesses: 1 V 1 strong that the Wheel notwithstanding its 5 l)()MINGO A. USINA,

thinness cannot be substantially deflected I THEODORE T. SNELL.

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