Patent GB-765332-A (GB)
Title: Improvements in or relating to presses
IPC: B42C5/00
Filed: 1952-05-02
Abstract: 765,332. Cutting-machines. HERON, J. U., and GILCHRIST, S. July 8, 1953 [May 2, 1952], No. 11118/52. Class 31 (1). [Also in Groups XV and XXIX] A guillotine comprises a support structure, a pair of reaction members fixed relative thereto, a pair of piston and cylinder assemblies between the reaction members and arranged coaxially with the cylinder heads in opposition, a pair of interconnected active elements opposed to the reaction members and operatively associated with one of the respective pistons, means supplying fluid under pressure to the piston and cylinder assemblies, and valve means controlling the flow alternately to and from the two cylinders to reciprocate the two pistons alternately to advance one active element and withdraw the other from the opposed reaction member. The supporting frame 15 in the form of a table has an opening 17 in the top, housing a cylinder block 18 which includes two coaxial back-to-back cylinders 19, 20 each fitted with a piston 21 adapted to actuate an outwardly-facing guillotine element 54-56 (Fig. 6), similar to element 22 (Figs. 2, 5), a hollow tube 23 being connected at one end to the element 54 and bearing against the piston 21 at the other, and a coil spring 24 therein assisting return of the piston 21. The elements 54 are interconnected by parallel guide-bars 25 sliding in the cylinder block 18. The two cylinders 19, 20 are alternately supplied with fluid, such as oil, so that the elements 54 are alternately urged backwards and forwards along the table 15 between side walls 39 and a base-plate 40. Fixed plates 60 (Fig. 6) similar to plates 41 (Fig. 2) are located at each end of the walls 39 and are adjustably mounted on the end frame 44 to vary the distance between the elements 54-56, 60. A pump (26, not shown) driven from an electric motor, supplies oil from a tank through a port 32 to a valve chest 30 whence it passes through inlet feed ports 31 to either cylinder 19, 20. Exhaust pipes 33 at each end of the valve chest 30 lead back to the tank through a filter. The valve chest 30 is closed at one end by a plate 34 and has a valve rod 36 sliding in the opposite end and actuating a slide valve 35 which comprises a sleeve 37 having peripheral flanges 38 at each end contacting the sides of the valve chest 30, the valve rod 36 being actuated continuously from the pump 26 through suitable gearing and connecting-rod 47. The valve 35 is constructed so that while one cylinder is receiving oil, the other is exhausting its oil through its port 31 and exhaust pipes 33 and the thickness of the flanges 38 is such that supply of oil to one cylinder begins a fraction before cutoff to the other. A pipe 52 from chest 30 lubricates the sliding valve driving mechanism 47 and a further pipe lubricates the bars 25. The guillotine mounting 54 associated with the tube 23 at its free end is adapted to slide along a rod 55 having a holding element 56 for the workpiece R placed against the plate 60 and supported on a retractive support member 61. The cutter blade 57 is secured to the mounting 54 by set-screws 58 and is urged forward with the element 22 against a spring 59. During the first part of the stroke, the tube 23 moves the holding element 56 and guillotine forward till the work R is gripped, the cutter 57 then moving to cut the work. The support 61 is retracted to allow the cut portion to drop and return just before the next cutting stroke commences. A second co-operating cutting blade may be provided in place of the fixed plate 60.