Patent GB-1332869-A (GB)
Title: Control arrangements for napped cloth shearing  machines
IPC: D06C13/00
Filed: 1971-01-15
Abstract: 1332869 Shearing fabrics DRABERT SOHNE 15 Jan 1971 [21 Jan 1970] 2012/71 Heading D1S A control arrangement is a machine for shearing a fabric having a base layer and a pile surface comprises means 4 for sensing continuously the thickness of the base layer and generating a signal having a value dependent upon that thickness, a device 9 for measuring the actual size of the shearing gap of the machine and for generating a signal dependent upon that size, regulating means 6 connected to receive both the signals and to generate a difference signal, and a re-set device 10 connected to receive the difference signal and to adjust the shearing gap of the machine until the difference signal reaches zero magnitude. A digital time delay operable independently of the speed of the fabric may be interposed between the means 4, 6 and a device is provided to damp the sensing means 4 during the time delay period. The shearing machine comprises a rotary cutter 23 cooperating with a ledger blade 8 to shear a fabric passing over a bar 7.  In one embodiment, Fig. 4, the device 10 operates to displace a stop 11, in the form of a hydraulically-operated edge follower, which hydraulically limits the gap between the blade 8 and the bar 7 and also displaces the device 9 with which, by means of a sensing device 14 the displacement value is converted into an electrical or pneumatic magnitude. The device 14 bears against a bracket 15 the setting of which can be altered by a spindle 16 with a locknut 17. The stop 11 is operatively connected to cylinders 18, 18a through a lever 19 pivoted at 20. If the stop 11 is displaced, the cylinders 18, 18a produce a new shearing gap which is limited by the lever 19 engaging the stop 11. When a seam 3 is reached, a control valve 21 causes a cylinder 22 to raise the cutter 23 and the blade 8 about the pivot 20 away from the bar 7. As this movement takes place, the pistons of the cylinders 18, 18a are moved downwards while the stop 11 moves to its terminal position and opens a path for the replacement flow of oil to the cylinders 18, 18a. Excess oil arising from the difference in cross-seotional area of the cylinders 18, 18a flows away through a bypass valve 24. The lowering of the cutter 23 is effected by the cylinders 18, 18a, the valve 21 cutting off oil to the cylinder 22 and opening a path for the escaping oil. In another embodiment, Fig; 5, the device 10 operates a cam 25 to bring a mechanical stop 12 into use. When the seam 3 passes through, the cutter 23 is raised by a pneumatic cylinder 22 controlled by a valve 26. After the seam has passed, the cutter 23 is lowered by switching over the valve 26. To prevent violent lowering, damping cylinders 27, 27a are fitted to the lever 19. After passage of the seam, the cam 25 displaces the stop 12 until the shearing gap corresponds to the fabric thickness.  In a further embodiment, Fig. 6, the cutter 23 and the blade 8 are stationary. On the passage of the seam 3, the bar 7 is lowered by a cylinder 22. The bar 7 is mounted between two guides 28 and its movement is limited by a stop 29 thereon engaging a hydraulic stop 11. After passage of the seam, the device 10 adjusts the stop 11 to the new fabric thickness. Alternatively, a mechanical stop may be provided. In a still further embodiment, Fig. 7, to allow a seam 3 to pass, the bar 7 is swung about a pivot 29 on an eccentric spindle 30. A spring 37 urges the bar 7 upwardly.