METHOD AND MACHINE FOR CUTTING BARS OR TUBES

Abstract: The method consists of rotating the work piece, e.g. a bar or a tube, while feeding the cutter into engagement with the work piece. Cutter feeding continues at most to a depth equal to half of the diameter of the work piece. The machine consists of a T-shaped main body (1) has at its front end a cutting device (9). A work piece conveyor (4) is located at the back end of the main body (1). A rotary chuck (8) is placed between the cutting device (9) and the conveyor (4). The rotary chuck (8) consists of a DC motor (25) connected to a worm (26) and a worm wheel (27) secured to a carrier (28), which in turn secured to a carrier body (29) and a cover (30) by means of bearings, and there is hydraulically operated work piece clamping assembly (31-35) in said carrier (28).

Description: METHOD AND MACHINE FOR CUTTING BARS OR TUBES FIELD OF THE INVENTION The invention disclosed herein refers to a method and machine for cutting bar stock which may find application in cutting blanks prepared from solid or hollow bar stocks of different length. BACKGROUND OF THE INVENTION There are known a method and a machine for cutting pipes especially for pipes of big diameters, which find application particularly in machining of concrete pipes. The method consists of initially fixing the pipe at a desirable angle between the pipe axis and the plane of cutting, and driving the cutting instrument into a compound (both progressive and rotary) motion towards the surface of the pipe, following either circular or elliptic trajectory. Cutting continues until the upper part of the pipe is cut off, at least 1/2 of the diameter of the pipe, after which the pipe is turned at an angle of 180 around its axis and the cutting continues. Cutting is accomplished after several passes of the cutter through the other half of the pipe. 2 The machine working in accordance with the method described heretofore consists of main frame upon which the pipe 10 be machined is fixed. At the upper part of the frame carriers are fixed to which a guide is secured with bearings on a traverse. The cutting instrument, comprising a cutting disk (1), is mounted on a holder on the guide above the pipe. There is known another machine for cutting rigid bodies , in particular pipes, consisting of main body, at the back end of which a feeder is mounted and the pipe TO be machined is placed next to it. and supporting rollers are placed laterally along the axis of the main body. There is a piston head mounted at the back end of the pipe with an opening in iτ ? and a mobile body inside the pipe which can be selected in accordance with the diameter of the pipe, said body being attached to a rope coiled on a drum. The body moves within the pipe by means of compressed air fed by a compressor through the opening of the piston, the compressor being fixed near the piston. The cuttmg mechanism mounted at the front end of the main body consists of a horizontal and a vertical beam, a pneumatic cylinder is bound to the horizontal one and a mobile beam - to the vertical one. Under the cutting disk there is a rubber ring engaging the shaft of the cutting mechanism and pressing tightly against the outer surface of the pipe thus making it rotate with the rotation of the shaft. The dιameτer of the rubber ring is bigger than the diameter of the cutting disk, the ring being elastic in radial direction (2). SUMMARY OF THE INVENTION Taking into account the prior state of art, the main object of the invention is to provide a method and a machine for cutting bar stock, by means of which a greater productivity of the process of cutting is achieved because of the regulation of the parameters ot cutting, and longer operating life of the cuttmg instrument. The object of the invention is achieved by a method for cutting bar stock consisting of the following steps: fixing the bar stock to be cut, driving the cutting mechanism and feeding it towards the outer surface of the bar stock. According to the invention after fixing the bar stock to be cut, it is rotated simultaneously with the linear progressive motion of the cutting mechanism and its feeding towards the outer surface of the bar stock, the cutting being performed 3 with variable number of revolutions, following a spiral trajectory and continuing at most to a depth equal to 1/2 of the diameter of the bar stock. According to a variant embodiment of the method for cutting hollow bar stock cutting continues to a depth equal to the thickness of the pipe wall. The method for cutting bar stock is embodied by a machine for cutting bar stock consisting of main body, where a feeder is mounted, the blank (pipe or bar stock) being fixed next to it along the axis of the main body on laterally placed supporting rollers and the cutting mechanism being mounted a? the iron! end o_ The main body. According to the invention a frame bearing the cutting mechanism v. situated at the front transverse end of the T-shaped main body and a rotary clamping de . ice is disposed between the cutting mechanism and the feeder. According to another embodiment of the cutting machine the cutting mechanism is an endless band saw disposed between two stretching rollers and is oriented in a vertical plane in the area of its working T-section by means of two pairs of twisting rollers mounted on the bearing frame. In another embodiment of the cutting machine the feeder is a step feeder, comprising α mobile carriage mounted on cylindrical guides and secured to the end of the piston bar of a feeding hydraulic cylinder, a supporting hydraulic cylinder is also immovably fixed on the mobile carriage with its supporting piston bar lying on one end of the bar stock, the opposite end of said piston bar being fixed on the mobile carriage. In another embodiment of the cutting machine the rotary clamping device consists of an engine connected to a worm, and a worm-wheel is immovably fixed on a carrier, which in turn is connected to a carrier body and a cover with bearings, while a second supporting hydraulic cylinder also resides in the carrier, its supporting piston bar lying on the bar stock on one end. the opposite end of said piston bar being secured on a second bearing mounted en the carrier. According to another embodiment of the machine the second bearing located on the rotary-clamping device is immobile. The application of the method and the machine for cutting bar stock, subject of the invention, provides increasing of the productivity with reduced material 4 consumption. The above advantages come as a result of optimisation of the process of cutting, where automatic control and regulation of the parameters of the cutting are possible in order to keep constant working power for a given son ot material. This is done by rotating the bar stock with adjustable revolutions, which change automatically with the decreasing of the diameter of the pipe in the process of cutting while keeping a constant, peripheral speed in the zone of cutting, as well as by automatically changing the speed of ieeding el the band saw as a function ol its changeable contact length with the section being cut and hence changing the cutting power. The cutting continues to a depth equal to the radius of the cross section in the case when solid bar stock is to be CUT, while when cutting pipes the cut is equai to the thickness of the pipe wall. Another advantage of the invenrion is the reduction of material consumption since the automatic optimisation of the process of cutting makes it possible to use a thinner band saw and ensures its longer lite of operation. The invention also provides considerable decreasing ol noise and pollution, as well as reducing the reject and accidents among personnel. The invention finds application in cuttmg bar stocks of different diameters and length. The preferred embodiment of the method for cutting bar stock is presented with the drawings enclosed herein as follows: Brief description of the Drawings Fig.l - Top plan view of the machine Fig.2 - Side view of the endless band saw Fig.3 - Cross- sectional view taken along the line A-A of Fig.l Fig.4 - Top plan view of the leeder Fig.5 - Cross-sectional view taken along the line B-B of Fig.4 Fig.6 - Top plan view of the rotary clamping device Fig. 7 - Cross-sectional view taken along the line C-C of Fig.6 Fig.8 - Top plan view of the band saw and the rotary clamping device with the bar stock being cut 5 DESCRIPTION OF THE PREFERRED EMBODIMENTS Further in the description an embodiment of the method for cutting bar stock in accordance with the invention will be described which can be used for cuttmg hollow or solid bar stock, a^ well as i n τ other materials such as concrete pipes, stoneware pipes, etc. The method for cutting bar stock is implemented in the following sequence: the bar stock to be cut is placed upon supporting rollers and is moved lor setting up in the rotary clamping device. Then the bar stock to be cut is rotated after fixing simultaneously with setting of the cutting mechanism in linear progressive motion and Ieeding it Towards the outer surface of the bar stock. The cutting is performed with variable number of revolutions with feeding the cutter along a spiral path, and continues m most to a depth equal to 1/2 of the diameter of the bar stock. When cutting hollow bar stock is to be done cutting continues to a depth equal to the thickness of the pipe wall. The method described heretofore can be performed by a machine in accordance with the invention, the machine consisting of T-shaped main bodyf 1). at the front end (2) of which a bearing frame (3) is disposed. A step feeder (4) is secured on the main body (1) and engages the bai stock to be cut(5). which in turn is set up along the longitudinal axis of the main body(l) on supporting rollers(6). A cutting mecnarasm ( Q ) with an endless band saw(14) is mounted on the bearing frameι ' 3), the rotary clamping deviee(8) being disposed between the band saw (14. and the feeder (4). A cooling system(lθ) is installed at the front end(2) of the main body ( I) and on both sides of the main body (1 ) an eiectricf 11 ) and a hydraulics 12 ) systems are mounted, and a lubricating system is disposed near them. According to a preferred embodiment the cutter is accomplished as an endless band saw (T4 ) stretched between the outer surfaces of two stretching roller3(15),and its working T-section being vertically oriented by means of two pairs of twisting rollers(16) mounted on the bearing frame(3). The feeder(4), preferably a step feeder, is mounted on the prolonged part of the main body(l). It consists of a mobile carriage (17) placed upon cylindrical guides i 16) and is fixed detachably to the piston bar (19) of a feeding hydraulic 6 cylinder (20). There is a supporting hydraulic cylinder (21) with a lid (22) immovably secured to the carriage(17). The front end of the piston bar (23 ) of the supporting hydraubc cylinder! 21 ) pamallv engages the bar stock to be cut. while tne fixed carrier (24). mounted on the carriage (17), partially engages the opposite end of the bar stock(5). and can be changed depending on the diameter of the bar stock or the pressing leg placed right upon the surface of the pipe to be cut. A rυtaπ clamping device 16. is disposed berween the band saw (14) and the feeder (4) and consists of an engine(25), preferably a DC engine, connected with a worm.26), the worm-wheel (27) being stuck immovably on a carrier (28), which m turn is secured with, bearings to the carriei body (29) of the rotan clamping device (8) and to a cover (30), which is immovably fixed on the carrier body(29). A second supportmg hydraulic cybnder ( 1 ) is mounted on the earner 126 » with a piston O 1 - (32) partially engaging the outer surface of the bar stock(5) tυ be cut with its front end (34). There is a second fixed bearmg (3 ) diametrically opposing said ι ~ onι end and leg(34). According to another embodiment of the machine the bearing 1 5 ) is movable. There is a covering lid (33) on the carrier (28) and pass grooves (36) through the cover (30), the carrier (28) and the carrier body (29). OPERATION OF THE INVENTION The machine for cutting bar stock operates according to the sequence of procedures of the metnod described heretofore. The bar stock.5) to be processed, a pipe for example, is set up on the supporting rollers (6) and then automatically caught b\ the step feeder (4) by means of the first fixed bearmg (24) and the supportmg piston bar (23) of the supporting hydraulic cybnder (21 ). The mobile carriage ( 17) is then moved along the cylindrical guides (IS) by the piston bar (19) of the feeding hydraulic cylinder(20).Being set up in this way, the pipe (5) is moved to the zone ol the rotary clamping device(8), released from the feeder 4) and rotated with 5 to 50 rev/min by a DC engine (25), a worm (26) and a worm-wheel (27). The endless band saw ( 14) is simultaneousl set m motion and ted towards, the outer surface of the pipe(5), the cutting being performed with variable revolutions and feeding of the cutter along a spiral path until the pipe (5) is cut. Meanwhile the feeder (4) is 7 back in its starting position, and so is the band saw (9) after the pipe (5) is cut. Further the pipe (5) is moved forward again by the feeder 4J and fed to the rotary clamping device (S),clamped, rotated and cut. the cycle bemg repeated until the pipe is cut to the necessary number of blanks. It ii to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scone of the claims to come hereinafter. 8 L i s t o f s y m b o l s - main bodv 19 - first piston bar - front end of the main body 20 - first hydraulic cybnder - bearing frame 2 . - first supporting hydraulic cylinder - step feeder 22 - cylinder s lid - bar stock 23 - piston bar of 1st suppoiτmg cylinder - supporting rollers 24 - first fixed bearing - back end of the main body 25 - DC engine - rotary clamping device 26 - worm - cutting mechanism 27 - worm - wheel - coobng system 28 - carrier 1 - electrical system 29 - carrier body 2 - hydraulic system 30 - cover 3 - lubricating system 31 - second supporting cylinder 4 - endless band saw 32 - piston bar of 2nd supporting cybnder *. - stretching rollers 33 - covering lid 6 - twisting rollers 34 - outer end of second piston bar 7 - mobile carriage 35 - second fixed bearing 8 - cylindrical guides 36 - pass grooves

Claims: PATENT CLAIMS 1. A method for cutting bar stock, consisting of fixing the bar stock to be cut, setting a cuttin wg- mechanism in motion and feeding it towards the outer surface ot the bar stock, characterised in that the bar stock(5) is rotated after being fixed, said, cuttmg mechanism is set simultaneously in linear progressive motion and fed towards the outer surface of the bar stock and cutting is performed with variable number of revolutions, with feeding the cutter along a spiral path and continues a; most to a depth equal to 1/2 of the diameter of the bar stock. 2. A method according to claim 1, characterised in that the cutting of hollow bar stock continues to a depth equal to the thickness of the pipe wail. 3. A machine fo ~ cutting bar stock, consisting ϊ a main body upon which a feeder is mounted, the bar stock being fixed on supporting rollers mounted upon the main body, and a mobile cutting mechanism at the front end of the main body, characterised in that a bearing frame(3) of said cutting mechanism(9) is mounted at the front transverse end(2) of the T-shaped main body(l). and a rotary -clamping device (8) is disposed between the cutting mechanising) and the feeder(4). 4. A machine according to claim 3, characterised in thai said cutting mechanism 9) is an endless bano sawi 14 disposed berween TWO stretching rollers(l5) and positioned vertically in the area of its working T-section by means of two pairs of twisting rollers(16) mounted on the bearing frame(3). 5. A machine according to claim 3, further characterised in that said feeder (4) is a step feeder ana consist? o! a mopile carriage ! H . disposed on cylindrical guides (IS) and secured to the end of the piston ban' 19) of a feeding hydraulic cylinder (20) .and a supporting hydraulic cylinder(21) is immovably fixed upon the mobile carriages 17). its supporting piston hart 3 s iying on one end of the bar stock(5), the opposite end of which bes on a fixed bearing(24) mounted en the mobile carriage (17), 10 6.A machine according to claim 3. further characterised in that said rotary clamping e ice'^ consists oi a DC engme (25) connected to a worm (26) and a woi ri-wneel .27; immovably secured to a carriei (2c... which m turn is secured τo a carrier body (29) and a cover (30) by means of bearings, and there is a second supporting hydraulic cylinder (31) in said carrier(28).its supportmg piston Par ( 32) lying on one end of the bar stock(5), the opposite end which hes on a second bearing(35) mounted on the carrier(28).

Inventors: NACHEV VALENTIN RASHEV, NACHEV, VALENTIN, RASHEV
Applicants: NACHEV VALENTIN RASHEV, NACHEV, VALENTIN, RASHEV
Application year: 1998
Main classification: B23D53
IPC codes: B23D53, B23D55