Abstract:
An apparatus for sawing a stone block to be severed into a plurality of slabs. The apparatus comprises a plurality of saw blades characterized by arranging said blades in series in the cutting plane of said blades. The cutting depth of each blade in the series is progressively deeper from the first blade to the last one so that a stone block which is successively fed to said series of saw blades may be efficiently severed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for sawing a stone block, and more particularly to an apparatus for severing the stone block into a plurality of slabs. 
     2. Prior Art 
     Recently there has been an increased demand for slabs of stone such as marble, granite and the like to be used for flooring, walling and the like. Conventionally the stone blocks cut at the mine or quarry are transferred to the processing factory where said stone block is severed into a plurality of slabs which may be finished by grinding. 
     In a conventional processing factory there is provided a work bed on which the stone block is fixedly laid, onto which a rotary cutting wheel having a peripheral portion embedded with finely divided particles of any hard material such as diamond is manually pressed downwards and forwards. When the saw blade has been advanced along the stone block length to the opposite side thereof after having cut the stone block by a predetermined depth, the saw blade is retracted to the initial position for repeating the advance-cutting work. During the repeated reciprocal travels of the rotary cutting wheel along the length of the stone block, the cutting depth is gradually deepened to complete the cutting work. Such method has been widely adopted and used for a long time despite fact that the retractive travels of the saw is obviously inefficient for the cutting work. It is sometimes possible of course to cut the stone block in a single stroke, namely without repeating said reciprocal travels of the saw, but the feeding rate of the saw must be considerably slower in view of incrementally increased resistance. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is, thus, to provide an apparatus for successively and effectively sawing the stone block to be cut into a plurality of slabs. 
     This object and other objects as well as various advantages of the invention may be readily appreciated by studying the following detailed explanation. The objects may be attained by providing a plurality of saw blades arranged in series in the cutting plane of the saws. The cutting depth of each blade in the series is progressively deeper from the first saw to the last one. Means are provided for successively feeding a plurality of stone blocks one by one on the work table towards the saws. 
     Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a schematic fragmentary side elevation of the first embodiment of the present invention; 
     FIG. 2 is a schematic fragmentary top plan view of the above embodiment with the top casing frame removed to show the arrangement of the saws; 
     FIG. 3 is a view similar to FIG. 1 but of a modification of the above embodiment; 
     FIG. 4 is a schematic side elevation of means for successively feeding the stone blocks one by one towards the saws and of auxiliary means for feeding said stone blocks when a new stone block is being supplied and said main feeding means is in the inoperative status; 
     FIG. 5 is a schematic side elevation similar to FIG. 1 but with a different feeding means; 
     FIG. 6 is a view similar to FIG. 5 but with a further different feeding means; and 
     FIG. 7 is a schematic perspective view of a means for turning the stone block around to be used for the feeding means shown in FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 illustrate the first embodiment of the invention, three stone blocks 1A, 1B and 1C, each being a granite block from the Inada District and being 20 cm width, 30 cm height and 120 cm in length, are longitudinally laid on a work bed 2 and positioned one after another. The first work piece 1A fragmentarily illustrated is urged towards the left in the drawing at the trailing end thereof by means of a push member 3 fixed at the free end of a piston 4 to be cooperated with a cylinder 5 of the hydraulic pressure apparatus. In this manner the work pieces 1B and 1C are also urged and fed towards the left on said work bed 2. It is preferable for the work bed 2 to have a plurality of longitudinal slits 2&#39; for obvious reasons which will readily be appreciated. 
     In the first step, there are provided twelve saw blades 10A, each of 50 cm in diameter, mounted on a shaft transversely extended from a gearing casing 12A and driven by an electric motor 13A of 75 h.p. Said saw blades 10A are each equally separated from adjacent blades by a spacer 11 of which thickness is adapted to comply with the desired thickness of the slab. The casing 12A is suspended from a machine frame 14 to be adjustable relative to the workpiece positioned on the work bed 2. 
     The above description also applies to the second and third saw groups 10B and 10C, except that the diameter of each saw blade of the last group 10C is 64 cm. As a matter of course, the exact dimension of these saw blades is not critical. In view of the three groups of saws provided in this embodiment, the level or positioning relative to the work piece and work bed of each saw group is so adjusted that the first 10A may cut the stone block by about 10 cm in depth or by approximately a third, the second 10B may cut the stone block by about 20 cm in depth or by approximately two thirds, and the third 10C may cut through the total thickness of 30 cm. In view of the fact that the first and second saw blades are both of 50 cm in diameter, the casing 12A is set higher than the casing 12B. By feeding the stone blocks at a rate of 5 cm/min. about 11 m 2  of cutting ability could be realized. 
     In reference to FIG. 3, there are provided two additional saw groups 10D and 10E each to rotatably mounted on the output shaft of the gearing casing upstanding on a lower machine frame 14&#39; so as to be arranged under said saw groups 10A and 10B. Each saw group comprises 26 saw blades arranged transverse to the direction of the stone block feeding travel. The upper and lower first saw groups 10A, 10D as well as the upper and lower second saw groups 10B, 10E, include blades being of 50 cm in diameter, are adapted to cut the stone block by 5 cm in depth, but the last saw group 10C, including blades of 64 cm in diameter, are adapted to cut by 10 cm in depth. 
     When the stone block of 40 cm in width, 30 cm in height and 120 cm in length is subjected to the cutting work at a feeding rate of 10 cm/min, the cutting ability per minute was about 47 m 2 . 
     In reference to FIG. 4, there is provided an auxiliary feeder means in addition to the feeder as explained in reference to FIG. 2 in order to successively feed the stone blocks. When the main hydraulic pressure apparatus 3, 4 and 5 is retracted for preparation of receiving a new supply of the stone block 1X, said auxiliary feeder comprising a grasper 23 mounted at the free end of a piston 24 to be cooperated with a cylinder 25 as the hydraulic pressure apparatus may relievingly serve to urge the stone block 1A towards the left in the drawing. 
     In FIG. 5 there is illustrated a different feeding means for the stone blocks 1A, 1B, 1C and 1D respectively fixedly laid on carriers 32A, 32B, 32C and 32D each having four supports 33 which may be engaged with an endless belt 34 longitudinally running on a lower machine frame 35. Said supports 33 may include a wheel to roll on a rail 34 so that each carrier 32 may be separately moved by any means not shown, or the carriers 32 connected with each other may be pulled or pushed as a whole by any means not shown. 
     In FIG. 6 the three groups of saws 10A, 10B and 10C are adapted to cut the stone block by only a half of the height or thickness thereof. The stone block 1C having been severed by a half cut in depth by the third and last saw blades 10C must be turned over to be subjected to the second cutting from the reverse side. For that purpose the half depth cut stone block 1D is taken up together with the carrier 32D by a fork lift having a fixed base 41L, vertically upstanding posts 42L, sleeves 43L guidedly movable along said posts 42L, and a pallet fixed to said sleeves 43L and having rails 34L on which the wheels 33 of the carrier 32D ride. The stone block 1E having been lifted up together with the carrier 32E is on rails 34&#39; laid on the upper frame 14 and transferred from the rail 34L on the pallet. The stone block 1F having been transported to the middle of the elongated upper rails 34&#39; is lifted up from the carrier 32F and turned over by a means generally represented by 50 to be explained in reference to FIG. 7 and then repositioned on the carrier 32F again. The carrier 32G on which the turned over stone block 1G is laid is taken up onto rails 34R on the pallet of the fork lift similarly having a fixed base 41R, vertical posts 42R upstanding thereon, and sleeves 43R, guidedly movable along said posts and provided fixedly with said pallet, and lowered down to be subjected to the second cutting. 
     In FIG. 7 the turning over means 50 comprises a frame consisting of two pairs of wall members 51, 51&#39; and 52, 52&#39;. Said wall members have respectively two pairs of plate members 53, 53&#39; and 54, 54&#39; respectively mounted to the concerned wall member by means of rods 55, 55&#39; and 56, 56&#39; to be, manually or hydraulically or by any other suitable means, moved toward or away from the concerned wall member. Said frame is provided with a pair of pulleys 57, 57&#39; at the opposite wall members 52, 52&#39; so that a pair of belts 58, 58&#39; extending around the respective pulley may raise or lower the frame assembly as a whole or may tilt the frame to be turned over. 
     When said belts 58, 58&#39; are lowered, the frame 51, 51&#39;; 52, 52&#39; in which said plate members 53, 53&#39;; 54, 54&#39; having been retracted toward the respective wall members, may snugly surround the stone block 1F on the carrier 32F. By moving the plate members 53, 53&#39;; 54, 54&#39; away from the concerned wall members and consequently toward the concerned sides of the stone block 1F, this can be firmly grasped in the frame. When raising the belts 58, 58&#39; and operating them to rotate the respective pulleys 57, 57&#39; by 180°, the frame and consequently the stone block held therein is completely turned over so as to be laid on the carrier 32F. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.