Patent GB-704629-A (GB)
Title: Automatic saw-blade planishing, stretching and straightening machine
IPC: B23D63/18
Filed: 1951-07-20
Abstract: 704,629. Making saws. SENARD, P. July 20, 1951 [July 20, 1950; June 28, 1951], No. 17256/51. Class 83 (4) Bending; rolling.-In a machine for straightening a band saw blade 3, Fig. 1, the blade is continuously fed longitudinally through a series of pressing rolls D intermittently engaging points across the width of the strip under the control of sets of feelers A, B which detect swells on the blade over straight and curved portions of its path. The set A comprises two rows of cranked feelers 22, 29 engaging opposite faces of the blade and supported on knife edges 21. Each feeler has a friction point 23 at one end engaging the blade and an adjustable set screw 25 at the other end which normally engages an electrical contact member 26 but is disengaged when the friction point 23 detects a swell in the blades. The blade 3 is guided between the feelers by guide rolls 14, 15, the rolls 14 being mounted directly on a vertical member 2 of the machine frame and the rolls 15 and feelers 22, 29 being mounted on a frame 10 which is vertically adjustable by a handwheel 12. The feelers 22, 29 are mounted on a slide 16 (not shown) in the frame 10 adjustable across the width of the blade by a handwheel 17. At the base of the machine the blade passes over a pair of discs 30, 31, Fig. 2, the disc 31 having a ridge 32 engaging the back of the blade. Releasable stationary guides 33 with hardened inserts engage the cutting edge of the blade. Rollers 38 adjustably engaged against the blade by a handwheel 42 maintain it in position. Axial adjustment of the disc 31 by a handwheel 34 permits accommodation of different widths of blade. Feelers 49 supported in two rows on knife edges 48 engage the outer curved face of the blade. The knife edges 48 are mounted on a support 41 which is vertically adjustable by a handwheel 44. The edge of the blade is further supported by rollers 45, 46 on the support 41 the roller 46 being transversely adjustable by a handwheel 47 to accommodate different widths of blade. The rolling device D for the blade comprises twenty sets of opposed rolls 64, 65, Fig. 5, the rolls 64 being alternately disposed on either side of a gap 59 in the machine frame and driven through shafts 62 interconnected by pinions 63 to an electric motor drive. The lower set of ten rollers 64 have three ridges opposed by three freely rotatable rolls 65 each of which is mounted on the end of a push rod 66 normally held in a retracted position by springs 67 and actuated by one of the rams 68 under the control of one of the thirty feelers 22, 29 in the set A. The next nine rolls 64 of the upper set of ten rolls have only two ridges opposed by pairs of rolls 65 similarly arranged and actuated by rams 68 each of which is under the control of one of the twenty feelers 49 in the set B. Each of the feelers 22, 29, 49 controls its corresponding ram 68 through an electronic circuit comprising a thyratron valve which passes a current to actuate a solenoid operated hydraulic valve for the ram at a pre-set time after the circuit through the corresponding feeler has been opened or closed. The apparatus also incorporates means for detecting and correcting edgewise curvature of the blade. The detecting unit C comprises a pair of photo-electric cells opposite light sources with beams passing near the edge of the blade arranged so that when the blade is straight one beam is cut off and the other passes to its cell. When the blade is convex on its edge both beams are cut and when concave both beams are uncovered. The cells control the actuation of a roll 65b  mounted on a carriage 101 at the top of the machine and engaging the surface of the blade near the back edge and also control the upper set of three rolls 65 engaging the blade surface near the toothed edge. The rolls 65 and 65b respectively correct the blade for convex and concave curvature at the back edge. The roll 64b on the carriage 101 is driven from the drive for the rolls 64 and the carriage is transversely adjustable by a hand wheel 102 (not shown) to accommodate the rolls 64b, 65b to different widths of blade. In a modified form of the machine rolling of the full width of the strip is performed by only three pairs of opposed rolls 64<SP>1</SP>, 65<SP>1</SP>, Fig. 10, mounted one above the other in a block 83 which is progressively moved across the width of the band, the rollers being operated to engage the strip under the control of three feelers which are also progressively moved across the band. In this machine the block 83 carrying the rollers 64<SP>1</SP>, 65<SP>1</SP> is mounted in slideways 84 and the rollers 64<SP>1</SP> are driven through shafts 62<SP>1</SP> which are axially slidable in driving pinions 63<SP>1</SP>. The band saw blade has a catch mounted thereon which actuates a hydraulic valve 89 after each complete revolution of the blade. The valve 89 controls a ram 88 which moves a lever 85 having a pawl 90 engaging a rack 93 on the block 83 causing it to be moved by one notch. When the block 83 has moved across the full width of the band a catch (not shown) on the machine frame is engaged to actuate a valve 95 controlling a ram 94 which returns the block 83 to its initial position. Single feelers are mounted at positions corresponding to those of the multiple rows, one on either side of the band over a straight portion and another on the outer side of a curved portion. Each feeler controls the engagement of one of the three rolls 65<SP>1</SP> with the band through an electronic time-lag relay. The lower feeler 49<SP>1</SP>, Fig. 12, is mounted on a slide 96 which is progressively moved across the width of the blade by a chain 97 coupled at its ends to the slide and running over sprockets 98, 99. The sprocket 98 is driven by a ratchet and pawl 100, 101 which is actuated by an electromagnet 104 energized on each revolution of the saw blade by the catch carried thereon. After the feeler has traversed the full width of the strip it is returned to its initial position by a hydraulic ram 105 controlled by an electromagnetic valve 106 which is actuated by a catch (not shown) on the slide support 43<SP>1</SP>. The remaining pair of opposed feelers on the straight part of the blade are mounted and moved across the blade in a manner similar to that of the feeler 49<SP>1</SP>. Specification 632,693 is referred to.