Patent GB-553926-A (GB)
Title: Presses
IPC: B21D22/10
Filed: 1942-01-27
Abstract: 553,926. Hydraulic press. BLISS CO., E. W. Jan. 27, 1942, No. 1132. Convention date, Feb. 25, 1941. [Class 69 (ii)] [Also in Groups XXII, XVI and XXXVII] A press of the kind in which the blanks to be shaped are pressed into a die by a resilient pad is constructed for use in a plant which permits the production over a given period of a relatively small number of each of a large number of parts, and is applicable for the production of aeroplane parts in a factory producing say 100 planes per month. As shown in Fig. 1 a number of die carriers 35 are arranged radially of a bed 32, and the carriers are moved inwards as desired by electric motors 55, Fig. 6, which are controlled by switches operated by electric magnetic relays, the circuits being controlled in such manner than only one carrier can be moved at a time into a position to coact with the resilient pad which is mounted on ball bearings in a press slide 24 secured to the rim 26 of a hydraulic press supplied with liquid by a pump 94, Fig. 11d, under control of a sliding valve operated by electric magnets 100, 101, the energization of which is controlled by switches operated by dogs on the carriers 35 which prevent the operation of the press until the dies are positioned correctly. The motors 55 advance and retract the carriers 35 by rack-and-pinion mechanism, but at the ends of the strokes the carriers are slowed down and stopped and started by the action of rollers 64 on cam members 62, 63 attached to the carriers, which ensure that the carriers stop in the correct position. The members 62, 63 which register with radial grooves formed in the bed 32 ensure lateral register, and the carriers during the pressing operation are supported by spring-supported studs let in the bed upon which the wheels of the carriers rest when in operative position. The pressing member is preterably in the form of a soft rubber pad 69, Fig. 3, mounted in an inverted rectangular box 70, of a width slightly greater than the die-carrier 35. The box 70 is mounted in a rotatable dial 74 provided with a circular rack 84 in engagement with a pinion 83 driven by a motor 82 which is energized to rotate the box 70 so as to cause it to assume one of the positions shown by full lines or dotted lines in Fig. 3, so as to register it with the operative diecarrier 35. The pinion 83 is associated with a starting and stopping device similar to the cam- and-roller device 62, 63, 64 described above, and the electric controls are so arranged that the box moves to its new position by the shortest route, i.e. by a rotation of 60 degrees in either direction. At each operating station a pressbutton switch is provided to cause the particular die-carrier to move inwards and to return after the pressing operation, and when one press-button has been operated the particular operation required cannot be interfered with by pressing other buttons, and one operation must be completed before another can be started. The switches used may be operated by electromagnetic relays, or by dogs on the carriers 35 and on the dial 74, and may be of the swing-arm type which operate when the arm is engaged and swung angularly by a coacting dog. The press slide is formed with dogs 110, 111, Fig. 11d, which operate switches SU, SD to stop up and down movement of the press by energizing the magnets 100, 101 controlling the valve plunger 99. When neither magnet is energized, the output of pump 94 is byepassed to the reservoir 96. Otherwise the output passes to the pressure cylinder 89 or to the retracting cylinders 92. The motor control system is so arranged that when the press-button which sets in motion the means for starting the operation of the dies in one carrier 35 is operated, the switches for controlling the operation of the other carriers are moved from closed to open positions. When the press-button is released, the circuits it controls are held closed by another switch until the return of the selected die-carrier after its dies have been operated upon. The motor 55 which advances the die-carrier is stopped when the carrier reaches the in-position and it is started in a reverse direction only after the ascent of the ram commences. Unless the carrier is stopped in exact register the press is not operated. The return of the ram may be controlled by a switch acted upon by a dog or the press slide when the slide reaches a predetermined " down" position, or by a switch (PS, Fig. 11d) actuated when the pressure in the cylinder 89 reaches a predetermined value. If while one die-carrier has been set in motion the controlling push-button of another carrier is operated, this carrier will commence to move only after the first carrier has completed its return movement. The means for controlling the rotation of the dial 74 is so arranged that unless the dial moves accurately to its position above the dies the press cannot be actuated. The invention may be applied to mechanical presses, and multi-speed motors may be employed on the die-carriers and on the dial. The press also may function at two or more speeds on the closing and opening strokes.