Patent GB-1168733-A (GB)
Title: Improvements in or relating to Tannery Machines.
IPC: C14B1/10
Filed: 1967-02-03
Abstract: 1,168,733. Buffing. LUIGI RIZZI & C. S.p.A. 3 Feb., 1967 [4 Feb., 1966], No. 5283/67. Heading B3D. [Also in Divisions C6 and G3] A tannery machine (of the type disclosed in Specification 878,001) for processing material such as pieces of leather or hide 7, Figs. 1, 2 and 3, comprises: a bolster roller 6, a conveying roller 8 and a processing cylinder 9 peripherally carrying at least one tool, means controlled by control mechanism for moving the roller 6 towards or away from roller 8 and cylinder 9, an adjusting member for adjusting the distance between roller 6 and cylinder 9, and a device for preventing the formation of end-of-stroke marks, such as linear scratches, on the material, which device comprises a mover, which, on being activated, moves the adjusting member from a pre-selected position so as to increase the distance between cylinder 9 and roller 6, means for activating the mover concurrently with the actuation of said control mechanism, and means for delaying the activation of said mover-activating means and causing the roller 6 to withdraw with respect to the instant of time in which said control mechanism is actuated, so as to obtain a displacement of the adjusting member prior to withdrawal of the roller 6 from roller 8 and cylinder 9. A machine, Figs. 1, 2 and 3, for buffing leather according to the invention, comprises side walls 1 and 2 connected by cross-beams 3, 4 and 5, and a rubber-covered bolster roller 6 journalled between plates 11 pivoted, at 12, to the side walls. The conveying roller 8 is mounted between arms 22 pivoted, at 23, to the side walls and biased by springs 24, which exert a nip pressure on the leather 7 as it passes between the rollers 6 and 8 to the buffing cylinder 9, which is provided with an abrasive peripheral coating 10. The cylinder 9 is rotatably supported between arms 27, which are pivoted, at 28, to the side walls, and carry an arm 40, and are connected by a beam 29 resting on the stems 32 of the pistons 33 of two double-acting hydraulic jacks 31 mounted on the cross-beam 4. The arm 40 carries an adjustable screw 39, which contacts the end of the stem 38 of a twin-piston 37, which is biased by a spring 36, and can reciprocate in the cylinder 35 of a valve 34, which controls the jacks 31 and consequentially the positioning of the cylinder 9, and is adjustably secured to the cross-beam 3 by a screw 46, which passes through a tapped bore in the crossbeam 3 and is attached, at its inner end, to the cylinder 35, so that the latter is displaced longitudinally, but not rotationally, when the screw 46 is turned. A graduated disc 47 provided with a handle 48 is mounted on the outer end of the screw 46. A pump 50 pumps oil from a sump 51, through pipes 52 and 41, into the middle of the cylinder 35, which is connected, through pipes 43 and 45, respectively, to the upper and lower ends of the cylinders of the jacks 31, and is provided with outlet pipes 42 and 44, through which oil is discharged into the sump 51. The cylinder 9 is rotated by an electric motor 30, which drives the pump 50 by means of a belt 49. The pipe 52 is connected to the middle of a slide-valve or distributer 53, in which is located a reciprocable three-piston stem 54. The distributer 53 is connected through pipes 55 and 56 to opposite ends of a cylinder 21, containing a reciprocable piston 20 having a rack 19, which engages a pinion 18 on a turntable shaft 17, to which are secured the discs 16 of two eccentrics, whose straps 15 are connected, by rods 14 and pivot pins 13, to the mounting plates 11 of the roller 6. A complete stroke of the piston 20, in one direction, turns the shaft 17 through half a complete turn. The three-piston stem 54 functioning as an armature can be moved axially to and fro by electromagnets 90 and 91, which are energized, respectively, by the actuation of a foot-pedal 62, which closes contacts 92 or 93 in the energizing electric circuit. When the pedal 62 is not depressed, the contacts 92 are closed and the electromagnet 90 is energized, thus keeping the stem 54 on the left, as shown in Fig. 3, and pipe 52 in communication with pipe 56, pipe 55 in communication with an exhaust pipe 57 and piston 20 on the left, so that the roller 6 is in its " open " position, i.e. swung away from the roller 8. When the pedal 62 is depressed, the contacts 93 are closed and electromagnet 91 is energized to move the stem 54 to the right, so that pipe 52 is in communication with pipe 55, pipe 56 is in communication with an exhaust pipe 58 and the piston 20 is moved to the right to swing the roller 6 into its " closed " position, as shown in Fig. 2, and to allow pressurized oil to flow from the cylinder 21, through a pipe 63, Fig. 3, to operate a hydraulic motor 26 driving, as by a belt 25, the roller 8. When the roller 6 is in its " open " position, the pipe 63 is closed by the piston 20 and the motor 26 does not operate. The cylinder 9 is set approximately in a desired position, by manual turning of the screw 39, and then automatically and more accuratelyset by turning the graduated disc 47 by means of the device for preventing the formation of endof-stroke markings, which comprises a doubleacting hydraulic cylinder 64, Figs. 1 and 4, secured to the cross-beam 3. Within the cylinder 64 is located a piston 65 on a stem 66, one portion of which has a diameter which is larger than that of the other portion on the other side of the piston. The free end of the portion having the larger diameter is pivoted to a link 67 having a hook, which detachably engages a pin on an arm 68 secured to the disc 47. The device also comprises a magnetic valve 71, into which pressurized oil is fed, through a pipe 75, from the distributer 53, and from which the oil can be discharged through an exhaust pipe 76. The valve 71 is connected to the ends of the cylinder 64 by pipes 69 and 70. Located within the valve 71 is a double piston 72 constituting an armature, which can be moved from one end of the valve to the other end by energizing one of the associated electromagnets 73, 74. When an operator depresses the pedal 62 to commence buffing operations on the leather 7, the electromagnet 74 is energized, the double piston 72 is moved to the right and pressurized oil pushes the piston 65 to the left, as shown in Fig. 4. When buffing is about to be completed, the operator releases the pedal 62 and the electromagnet 73 is energized to move the double piston 72 to the left, so that pressurized oil pushes the piston 65 to the right, thus gradually turning the disc 47 clockwise and gradually swinging the cylinder 9 away from the leather 7 and roller 6, and avoiding the formation of end-of-stroke markings on the buffed leather.