US3756216A

US3756216A - Method for cutting stone with pressure operated means

Info

Publication number: US3756216A
Application number: US00138476A
Authority: US
Inventors: R Fletcher
Original assignee: FLECHTER H CO
Current assignee: FLECHTER H CO
Priority date: 1971-04-29
Filing date: 1971-04-29
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04

Abstract

In producing dimension stone, an actuated cutter is progressively directed against a surface of a mineral body to remove material and form a V-shaped indentation which constitutes a rectilinear parting extending inwardly for an appreciable distance along a desired plane of separation. The mineral body is thereafter engaged at points above and below the parting by pressure operated cutting means to form dimension stone pieces. The parting, especially when employed at two opposite sides of the mineral body, controls the cutting action to form the pieces with vertical corners each of whose surfaces intersect the Vshaped indentation to provide arrises which are characterized by sharply defined rectilinearity. Rectilinear partings at two sides of a mineral body may be formed simultaneously by means of a pair of actuated cutters and cutter supporting structures and the cutters may be moved in reversing paths of travel at opposite sides of a mineral body in opposed synchronized relationship. The actuated cutters and their supporting structures may be combined with the pressure operated cutting means as an integral part thereof or they may be employed independently.

Description

United States Patent 1 Fletcher et al.

[451 Sept. 4, 1973 METHOD FOR CUTTING STONE WITH PRESSURE OPERATED MEANS [75] Inventors: Ralph A. Fletcher, Bedford, NH;

Joseph R. Oliver, Lowell, Mass.

[73] Assignee: H. E. Fletcher Co., Weitford, Mass.

[22] Filed: Apr. 29, 1971 [21] Appl. No.: 138,476

2,627,640 2/1953 Gamich 125/23 R 1,534,353 4/1925 Besser 125/1 2,188,318 l/l940 Siderit 125/23 C Primary Examiner-Harold D. Whitehead Attorney-Munroe H. Hamilton [57] ABSTRACT In producing dimension stone, an actuated cutter is progressively directed against a surface of a mineral body to remove material and form. a V-shaped indentation which constitutes a rectilinear parting extending inwardly for an appreciable distance along a desired plane of separation. The mineral body is thereafter engaged at points above and below the parting by pressure operated cutting means to form dimension stone pieces. The parting, especially when employed at two opposite sides of the mineral body, controls the cutting action to form the pieces with vertical comers each of whose surfaces intersect the V-shaped indentation to provide arrises which are characterized by sharply defined rectilinearity.

Rectilinear partings at two sides of a mineral body may be formed simultaneously by means of a pair of actuated cutters and cutter supporting structures and the cutters may be moved in reversing paths of travel at opposite sides of a mineral body in opposed synchronized relationship. The actuated cutters and their supporting structures may be combined with the pressure operated cutting means as an integral part thereof or they may be employed independently.

4 Claims, 18 Drawing Figures [451 Sept. 4, 1973 United States Patent [1 1 Fletcher et al.

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PATENTEB SEP 4 I975 SHEET 10 [1F 10 .l nun METHOD FOR CUTTING STONE WITH PRESSURE OPERATED MEANS BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates to a method and means for processing granite and other mineral bodies to produce desired mineral shapes, and more particularly, the invention is concerned with cutting blocks of granite especially with guillotine type machines, to provide dimension stone pieces of the class commonly made and sold in the granite industry for use as granite curb, ashlar pieces, veneer and other products.

2. DESCRIPTION OF THE PRIOR ART An important development in the granite industry in processing large blocks of granite and other stone has been the utilization of a guillotine type machine" to cut up the blocks to form smaller pieces of desired shapes. The term guillotine or guillotine type" as employed in the specification refers to a machine having vertically movable cutting means which may, in some cases, include a powered set of chisels engageable against top and bottom surfaces of a block of stone to carry out vertical cutting. One typical machine of the guillotine type referred to is the Hydrasplit machine manufactured and sold by the Park Tool Company of St. Cloud, Minn.

The guillotine type cutting operation described produces slabs or sections with cutting being initiated along relatively straight lines extending across top and bottom surfaces of the block. However, a very troublesome difficulty is experienced in controlling the planes of separation extending between the top and bottom sides of the block and it frequently happens that separation may take place in an irregular manner with jagged corner portions being fonned.

When this occurs, some of the irregular projecting portions are required to be cut away to produce a satisfactory product and there is thus entailed the operation of dressing each of the stone sections with a stone cutting tool usually operated by hand. Thus a loss of material and workman's time may take place and the production cost of the finally formed dimension stone is undesirably increased.

It has also been found that the naturally occurring grain or crystal formation of granite and various other classes of stone may be of considerable importance, and if the plane of cutting by the guillotine is not properly oriented with respect to the grain, difiiculty may be encountered while the grain acts as a deterrent to the formation of satisfactory dimension stone products.

SUMMARY OF THE INVENTION It is a chief object of the invention to provide improved methods cutting mineral bodies and to devise means for forming in such mineral bodies one or more partings or fissures which are capable of defining and controlling planes of separation along which cutting may be carried out by pressure operated cutting means.

Another object is to provide improved method applying partings at two opposite sides of a mineral body simultaneously.

Another object of the invention is to provide a method of processing a relatively large block of granite or other stone to cut off sections or slabs which are of a desired size and which are characterized by the formation of corner portions each of whose surfaces intersect to provide arrises of sharply defined rectilinearity.

It is a further object of the invention to devise a method preforming successive portions of a block of granite, as it enters the cutting station of the guillotine machine, with vertical partings which can provide for subsequent separation taking place in substantially vertical planes of separation.

Another object of the invention is to provide improved method for simultaneously forming partings in a block of granite in timed relation to the operation of a guillotine machine cutter mechanism.

Another object of the invention is to provide a method of cutting which is not limited in the orientation of the plane of cutting with respect to the grain structure of the stone.

The nature of the invention and its other objects and novel features will be more fully understood and appreciated from the following description of selected embodiments of the invention shown in the accompanying drawings in which:

FIG. 1 is a front elevational view of a typical guillotine machine showing a block of granite being advanced through the machine and further indicating the apparatus of the invention employed in firming partings at two opposite sides of the block;

FIG. 2 is a fragmentary elevational view showing portions of one side of the guillotine machine and the tool means of the invention combined therewith;

FIG. 3 is a plan cross-sectional view taken on the line 33 of FIG. 1;

FIG. 4 is a detail plan view of one of a pair of tool units employed in the invention;

FIG. 5 is a front elevational view showing details of the tool mechanism of FIG. 4;

FIG. 6 is a side elevational view of the tool mechanism shown in FIGS. 4 and 5;

FIG. 7 is a fragmentary perspective view illustrating portions of a guillotine machine and further indicating one of the tool units of the invention mounted thereon;

FIG. 8 is a detail elevational view of the structure of FIG. 6 viewed from an opposite side thereof;

FIG. 9 is a detail elevational view of the structure shown in FIG. 5 but viewed from an opposite side thereof;

FIG. 10 is a diagrammatic view illustrating wiring details and components for the control circuitry employed in operating the tool mechanism in a suitably timed relationship to operation of the guillotine machine;

FIG. 11 is a plan view illustrating diagrammatically a block of granite which has been formed with partings by means of the cutter mechanism of the invention.

FIG. 12 is a detail cross sectional view of the upper side of the block illustrated in FIG. 11 and further showing the guillotine cutting means moving downwardly to make a cut;

FIG. 13 is a fragmentary view showing the block of FIGS. 11 and 12 cut into two sections along the plane of the partings and illustrating vertical comer portions which are formed with arrises of sharply defined rectilinearity.

FIG. 14 is a composite perspective view illustrating granite sections, one conventionally cut and the same section cut in accordance with the method of the invention;

FIG. 15 is an elevational view showing assembled blocks in a structure;

FIG. 16 is a diagrammatic view illustrating a method of cutting a block of granite while supported in an inclined position to produce an angled cut;

FIG. 17 is another diagrammatic view illustrating a method of cutting a block supported in an oppositely inclined position to that of FIG. 16;

FIG. 18 is a detail perspective view of a block cut by the method of the invention.

With the foregoing problems and objectives in mind, we have conceived of an improved method and means for controlling the forces exerted by pressure actuated cutting means such as is employed in a guillotine type machine. Our improved method, in one preferred embodiment, is based on the concept of locating a block of granite in a guillotine machine and subjecting the block to the action of actuated cutters to form partings simultaneously along two opposite sides of the block. We have discovered that by progressively moving the cutters along the block in a reversing path of travel and by repeatedly applying the cutters at a high rate of speed and with sufficient intensity, two results are realized. First, the cutters remove material to form relatively straight V-shaped indentations which can be located in predetermined orientation to the plane of cutting of a guillotine machine. Secondly, rapidly impacts of the actuated cutters along extended paths of travel provide shock forces which are transmitted through the stone and which open up minute fissures or cracks extending transversely inwardly of the stone for appreciable distances. These indentations and the fissures or cracks constitute partings which are characterized by a high degree of rectilinearity. The dual partings thus initiated operate, we find, to control in a highly effective manner the cutting action of a guillotine machine when applied across top and bottom surfaces extending between two such partings. As a result, pieces cut off are formed with corners each of whose surfaces meet to form arrises of uniform and sharply defined rectilinearity, adding greatly to the value of the product while avoiding costly processing.

An important feature of the method consists in traveling a pair of the actuated cutters progressively downwardly along a desired path of travel in synchronized relationship, and then traveling the tools upwardly along the same path in order to deepen the partings achieved. As noted above, a further important feature of our method consists in orienting the dual cutting paths with a predetermine plane of downward travel of guillotine cutter means so that the partings and the plane of guillotine travel coincide with one another and each of the two operations, namely, forming the partings and then cutting off sections can be carried out in rapid sequence without requiring adjustment of the granite block in the guillotine machine.

In carrying out the method of the invention, therefore, a block of granite is located on a conveyor member and a section of the block is advanced through the guillotine machine into predetermined register with the guillotine cutting means. In this position of register, the block is engaged at two opposite sides by actuated stone cutter mechanisms which are horizontally moved from a normally spaced or home position into a contact with the sides of the block. Thereafter, the cutters in each cutter mechanism are simultaneously actuated while the two mechanisms are travelled downwardly along opposite sides of the block, then upwardly, and then back to the home positions of each of the mechanisms. The cutter mechanisms are shown in respective home? positions in FIG. I in dotted lines closely adjacent to the machine sides 2 and 4. A second dotted line, also shown in this FIGURE indicates the positions of the cutter mechanisms at the end of their downward travel.

For these several operations, we have devised a special apparatus which in one preferred form may be mounted on opposite sides of a guillotine type machine and operated in combination with a guillotine machine in a desirable manner.

In the form of apparatus noted and hereinafter described in detail, reference is made to the use of twin cutter mechanisms mounted in a guillotine machine at either side of a conveyor member on which the block of stone is supported and moved as required. However, it is not intended that the invention be limited to the use of a twin cutter mechanism, and we may, in some instances, desire to utilize one of the twin cutter mechanisms either in conjunction with a guillotine machine or separately of the guillotine on a block of stone received on a supporting structure so that cuts may, if desired, be made along any one or all of four sides of the block of stone.

Referring more in detail to the drawings, FIGS. 1 3 inclusive, illustrate a stone cutting machine of the guillotine type generally indicated by the arrow R. The machine R includes vertically disposed side portions 2 and 4 which have hydraulic rams contained therein. Located between the side portions 2 and 4 is an upper frame part 6 and a lower frame part 8. Mounted for reciprocating movement in the upper housing part 6 is a set of loading blocks or chisels indicated by the numeral 10. Also mounted in the lower housing 8 is a second set of loading blocks or chisels indicated by the numeral 12 and arranged in vertically spaced alignment with the chisels l0.

It will be understood that the hydraulic rams referred to as being located in the side portions 2 and 4, although not shown in the drawings, are of conventional type and are operatively connected in a well-known manner to the chisels 10 to provide for moving the chisels downwardly against a block of stone located therebelow. Preferably the block of stone is supported in a raised position and for this purpose the guillotine machine R may be provided with a multiple roller conveyor for receiving and advancing a block of stone into a desired position relative the chisels 10 and 12. As shown in FIGS. 1 3, the conveyor may comprise a lead-in conveyor section Vi and a second lead-out conveyor section V2.

In accordance with the invention, we combine with the guillotine type machine construction described a pair of actuated stone cutter mechanisms. Each of the cutter mechanisms includes, as principal components thereof, a wedge-shaped actuated cutter element and actuating means for impacting the cutter with considerable shock force, a tool supporting structure for moving the cutting element into and out of contact with the block of stone, and means in the supporting structure for advancing the cutter element along a reversible path of travel while in contact with the block of stone.

In one preferred embodiment of the invention, we may provide for mounting the cutter mechanisms at a front side of the guillotine machine R on a pair of slide bars T20, T20-', solidly secured as by welding or other means to the upper frame section 6 of machine R.

These slide bars are most clearly shown in FIG. 1, and slide bar T is also indicated in dotted lines in FIG. 2. As shown in this latter figure, the bar T20 extends above and below a rib portion 21 of frame section 6 to form retaining edges and similar edges are comprised by the bar 20..

Slidably engaged about these retaining edges of the slide bar portions T20 and T20 are respective horizontally adjustable channel slides 22, 22', more clearly shown in FIGS. 4 9, inclusive.

As one means of carrying out horizontal adjustment of the channel slides 22 and 22' on bars T20 and T20, we provide pressure operated cylinders C and C solidly fastened along outer sides of the bars T20, T20 as shown in FIGS. 1, 4 and 5. These cylinders act through plunger rods 26 and 26' attached at respective ends of the slides as suggested in FIG. 4.

Supported at inner sides of the slides 22, 22' are vertically disposed cutter frame pieces 28, 28' which consist of elongated bars of rectangular cross section constructed with lengths such that they extend down to the lower conveyor sides of the conveyors V1 and V2 as shown in FIG. 7.

In combination with the frame pieces, we provide respective cutter supporting slides 30 and 30', arranged for vertically adjustable travel and mounted at side portions of the slides 30, 30' are cutter members generally indicated at F, F as shown for example in FIGS. 5 9 inclusive. Vertical travel of slides 30, 30' on respective frame pieces 28, 28' is carried out by attaching the slides to sprocket chains 32, 32'. The

sprocket chains

32, 32 have their lower ends engaged around idler sprockets 34, 34' rotatably received on shaft means 36, 36', in turn located in the frame 28, 28', as shown most clearly in FIGS. 5, 6, 7 and 9. Upper ends of the chains 32, 32' are engaged around driver sprockets now shown in the drawings but received on shafts of the hydraulic motors J, .I'. The motors J, J are horizontally supported on bracket structures 38, 38' solidly secured to respective vertical frame pieces 28, 28'.

As shown in FIG. 8 cutter slides 30, 38 have fixed thereto projecting sleeves P, P through which are slidably received vertical pull rods 50, 50'. Each of these pull rods has at their lower portions coiled

springs

52, 52 which are bottomed on

respective collars

50a, 50a fast on respective pull rods. The coil springs are of a diameter suitable for being engaged and compressed by sleeves P, P at points in the downward travel of the slides 30, 30'.

An important feature of the invention may be to control the length of the indentation which is made by adjusting the

collars

50a and 50a on their respective pull rods into higher or lower positions as required. When thus adjusted, these collars limit the extend of cutting according to the positions of the collars on the rods.

Upper portions of the pull rods 50, 50' are slidably contained in tubular bearing 50b, 50b which are solidly fastened as by welding to vertical plates 50:, 50c, in turn attached to respective portions of the motor bracket 38, 38'. The upper extremity of the pull rods 50, 50' have transverse arms 54, 54' secured by

screw elements

50d, 50d. Located between the arms 54, 54'

and the tubular bearing 50b, 50b around the pull rods are coiled

springs

50a, 50a which in a normally extended position maintain the pull rods and transverse arms in a raised position such that angled ends of the arm are held out of contact with valve actuator buttons Ha, Ha on valve H, H. During downward travel of the

slides

30, 30, sleeves P, P engage the springs 52, 52', and at one point begin to force the pull rods downwardly compressing springs c, 50c and moving the angled ends of arms 54, 54' to depress the valve actuator buttons Ha, Ha.

The cutter members F, F include V-shaped cutting vtools of the type commonly employed in pneumatic stone cutters and indicated in the drawings by the

numerals

40, 40. The

cutting tools

40 and 40 are mounted in horizontally disposed support arms 42, 42' which are adjustably mounted around vertical pivot elements 44, 44'. A standard type of pneumatically operated

mechanism

46, 46 reciprocates the cutting tool in the customary manner. Spring means 48 (FIG. 8) serves as a cushioning device when reciprocating movement is taking place.

Also included in the cutter mechanisms now described are a number of control devices including valves, switches and cam devices and these control members may be conveniently considered in connection with a description of a typical cutting operation to form partings on two sides of a block of granite.

A first step in the cutting operation of the invention is to locate a block S of stone such as granite in a desired position to position a required section of the block in suitably registered relation with the cutting means of the guillotine machine. During this first operation, the pair of cutter mechanisms are in retracted or home position at either side of the guillotine machine R as shown in dotted lines in FIG. 1.

Considering one of the cutter mechanisms, for example, the cutter mechanism'at the left hand side of the machine as viewed in FIG. 1, it will be observed that there are provided on the front side of the guillotine machine valve units generally indicated by the reference characters B, B.

With the block of stone S suitably located, as described above, an operator moves valve A (FIG. 10) connected to a compressed air line capable of furnishing a pressure of, for example, p.s.i. Compressed air from valve A is led through suitable conduit means to the valve units B, B. Attention is directed to the horizontal cutter mechanism occurring at the left hand side of machine R as viewed in FIG. 1. With reference to this cutter mechanism, flow of compressed air to valve means B pressurizes a large pilot which shifts a valve spool in a well-known manner to let air out of a valve port in B into the pneumatically operated cylinder C. This causes cylinder C, through its plunger attached to the cutter mechanism, to move the cutter slide 22 from its home position, shown in dotted lines at the left hand side of FIG. 1, into the full line position indicated in that FIGURE. The slide 22 moves into contact with an adjacent surface of the block of stone S and is held there firmly by the constantly maintained pressure of air cylinder C.

As the slide 22 moves into contact with the block S, a pivotally mounted projecting arm 31 on the slide strikes the stone and is rotated through a short are of travel to force an angled tip portion 31a against a valve button aD. As shown in FIG. 10, valve button aD delivers air to valve D which furnishes air to the cutter means F. The cutter element 40 is caused to move in and out at a rapid rate providing a series of repeated impacts at a speed of as high as 2,000 cycles per minute exerting an impact force of from I to S p.s.i. and

greater. Simultaneously with the cutter element 40 being activated, compressed air from the opened valve D is also furnished to a small pilot on valve G indicated diagrammatically in FIG. 10 and also shown in FIGS. 5 and 6. Valve G is thereby placed in a position to feed a hydraulic fluid such as oil to the motor J which drives the chain 32 together with a cutter slide 30 and cutter mechanism F downwardly along the side of the block S.v Movement of the chain and cutter slides continues downwardly until the projecting sleeve P engages with and compresses spring 52. At a point approximately at the bottom of the downward travel of the cutter slide, the rod P is pulled downwardly against the resistance of spring 50c and arm 54 contacts and opens valve H.

When thus opened, valve H feeds air to a large pilot on valve G and another pilot on valve A. The large pilot on valve G shifts the spool against a small pilot and causes the motor I to be reversed, thus starting the chain operated slide in a reverse path of travel upwardly of the stone. The pilot on valve A resets this valve in its initial position.

It will be observed that the projecting sleeve P and slide is attached to the chain 32 in a position such that the slide 30 is at the bottom of the block S when the motor J is caused to reverse the movement of the chain.

Valve H has no spring return but depends on its air pilot to return it to its off position. Therefore since the pilot is not energized it stays on even though its roller comes off cam L when the motor reverses.

Since valve A is now off, the large pilot on valve B is no longer energized and since valve B is pilot-operated only and since its small pilot is not energized either, the spool remains stationary.

As the slide 30 moves upwardly returning to its top position, a cam L on the slide moves up against a roller on a valve E supported below the valve H as shown in FIG. 8. Valve E when opened resets both valve B and valve H to their original positions by energizing their pilots.

When valve H closes it bleeds the large pilot on valve G. When valve B shifts, it causes cylinder C. to move the horizontal slide 22 away from the stone and into its home position as indicated in dotted lines at the left hand side of the machine R, as viewed in FIG. 1.

As the arm 31 moves away from the block S, button aD operates to bleed the pilot on valve D letting a spring close it which stops the cutter F and also bleeds the small pilot on valve G. Both pilots on valve G are now bled and the spool is centered by means of springs, thus stopping the motor J.

It will be seen that all of the cutter components are thus returned to their initial start position with a V- shaped indentation having been cut during both downward and upward travel of the cutter element 40.

The dual cutter mechanisms now described are further combined in interlocking relationship with the guillotine machine control mechanism by means of dual interlocking switches which are operated on the guillotine machine at its front side in a position such that they may be engaged by the

horizontal slide mechanism

22, 22 during their cycle of movement. The two interlocking switches are denoted by the reference character MV, M'V and are most clearly indicated in FIGS. 1 and 7.

Mounted for engagement with the switches MV,MV' are stop elements M1, M1 mounted at the tops of the frame pieces 28, 28' respectively, as is also most clearly shown in FIGS. 1 and 7. As indicated in the dotted line positions at opposite sides of machine R, these stop elements M1 and M1 are arranged to move against the pivotal switch arm of switch MV,MV' and in these positions, the stops actuate the switch MV,MV' to provide for the machine being operated. However, at all times when the stops are out of contact with the switches MV,MV' the guillotine is prevented from being operated and thus accidental movement of the guillotine cutting means cannot occur while the stone cutter mechanisms are in operation.

In this interlocking valve arrangement, we may also provide for a small pilot in valve B being left pressurized so that valve B, B keeps cylinder C, C pushing respective horizontal slides and stops M1, M1 against switches MV,MV' in their home positions. In these positions, therefore, the slides and their stops are activating the interlock switches. We may also provide the valve G in a form such that all parts are blocked in the center position with the result that the motors J, J are locked and thus cannot allow the vertical slides 30, 30' to fall away or jiggle down while the guillotine is being operated.

FIG. 11 illustrates diagrammatically the block of stone with V-shaped indentations W, W formed therein and also minute fissures T, T which form a continuation of the indentations. These cuts and fissures result from the cutters having been applied in the manner described in accordance with the invention and FIG. 11 also illustrates the cutter mechanisms in a retracted position after the cutting operations have been completed and the cutter mechanisms are in home positions with the interlocking switches MV, MV' closed.

When the operation of forming V-shaped indentations and fissures at the two sides of the block have been completed, the machine operator actuates controls for the hydraulically powered cutting means of the guillotine machine and the upper set of chisels or cutting members are lowered into contact with the top of the block S in register with the two V-shaped indentations as suggested diagrammatically in FIG. 12. Hydraulic pressure of substantial magnitude is then exerted through the upper set of chisels and the section of the block of stone lying between the machine stop and the cutting chisels is instantly cut off as illustrated in FIG. 13.

As may be most clearly observed from an inspection of FIG. 13, there are formed in both the block S and the cut section SC vertical corners each of whose surfaces intersect the V-shaped indentations to provide beveled arrises as Wa, Wa'. These arrises extend vertically and are characterized by sharply defined rectilinearity as indicated in the drawings. It will be appreciated that forming these corners with their beveled arrises of such a high degree of rectilinearity result in a greatly improved product which is readily marketable without further processing, and therefore substantial savings and other advantages are realized by the invention method. It is further pointed out that by combining these beveled arrises with roughened stone surface portions included therewithin, in a manner such that the roughened surfaces are exposed to view when assembled in a building structure, there is achieved a greatly enhanced architectural quality with an attractive rough-textured effect being realized.

It is also found that by cutting V-shaped indentations at opposite sides of a block and then applying the guillotine cutting means at the top and bottom of the block, there is also realized horizontal arrises as W0, We. of appreciably greater rectilinearity than can be accomplished by a conventional guillotine cut.

In FIGS. 14 and there have been illustrated blocks of granite S1 and S2 illustrating in the case of granite block S1 commonly encountered irregularities in stone sections cut by conventional guillotine machines and the block S2 is intended to illustrate the same block when formed by the method of the invention to produce the arrises S3, S4, S5, etc. characterized by sharply defined rectilinearity.

FIG. 15 illustrates a series of blocks S6, S7, S8, made according to FIG. 14, and arranged with arrises in abutting relation to provide smooth joints and to present outer exposed surfaces of a building structure or facing in which roughly textured portions are included to improve architectural appearance.

The method and apparatus disclosed may be moditied in various respects and utilized for other types of cutting operations. For example, we may provide a pivotally mounted conveyor C2 which can be adjusted to assume a position of angularity as shown, and on which a block S10 may be supported in an inclined position. Cutting chisels C5 act in a plane of cutting C6 which is normal and which results in a beveled cut being produced when the cutter mechanisms of the invention are utilized to form V-shaped indentations and fissures and the chisels C5 are thereafter activated.

FIG. 17 discloses another pivotally mounted conveyor C14 on which a block S12 may be supported in a reversely inclined position to that shown in FIG. 16 and here again, cutting may proceed in a plane C7 which forms an undercut side to the block of granite. In each of these assemblies, it will be understood that the conveyors C2 and C6 are adjusted by means of a hydraulic lift cylinder such as C8 shown in FIG. 16 and C9 shown in FIG. 17.

In FIG. 18 a block S20 is illustrated with the partings formed by cutting indentations in the manner disclosed above. These parting areas are indicated at S22, S24, S26 and S28 and they function to produce uniform finished edges which extend around a central rough surfaced area S30, with the result that a contrast between a relatively even border and roughened inner surfaces is realized.

Other changes and modifications may be practiced.

We claim:

1. In a method of cutting a block of granite presenting upper and lower sides and vertical surfaces extending therebetween, the steps which include supporting the lower side of the block in a stationary position, impacting a cutter element with shock forces against one of said vertical surfaces of the block, progressively moving the impacting cutter element along a path of travel which extends from the upper side of the block to the lower side thereof to provide a vertical parting indentation, and then reversing the path of travel of the cutter element along the parting indentation to induce at innermost portions thereof formation of minute fissures which define a predetermined plane of separation of the block of granite, thereafter engaging said underside and upperside of the block with cutting means vertically movable in a plane which coincides with the said parting indentation, and then exerting pressure through the cutting means to split the stone along the said predetermined plane of separation, thereby to form dimension stone pieces with corners each of whose surfaces intersect along relatively straight lines and provide arrises which are characterized by sharply defined rectilinearity.

2. A method according to claim 1 in which both of the said vertical surfaces of the block are impacted with shock forces to form minute fissures which lie in a common vertical plane.

3. A method according to claim 2 in which the lower side of the block is supported in a stationary position in a guillotine machine and the cutting means for forming vertical indentations are moved along said vertical paths of travel within the vertical :sides of the guillotine machine.

4. A method according to claim 3 in which movement of the cutting elements along the vertical surfaces of the block opens and closes an. electrical circuit for controlling the operation of the guillotine cutting means.

* i i I ll

Claims

3. A method according to claim 2 in which the lower side of the block is supported in a stationary position in a guillotine machine and the cutting means for forming vertical indentations are moved along said vertical paths of travel within the vertical sides of the guillotine machine.

4. A method according to claim 3 in which movement of the cutting elements along the vertical surfaces of the block opens and closes an electrical circuit for controlling the operation of the guillotine cutting means.