Patent GB-906679-A (GB)
Title: Press control device
Inventor: MAURICE COHN
IPC: B21D43/02
Filed: 1960-08-05
Abstract: 906,679. Stop and relief-mechanism for strip feed presses. COHN, M. Aug. 5, 1960 [Aug. 6, 1959], No. 27319/60. Class 83 (4). A device for shutting off a power press to which strip or stock is fed comprises a movable element engaging the stock fed to the press and moved thereby a predetermined distance in one direction, a follower element power driven on said one direction, switch means operatively connectible with the power means of the power press for shutting off the press, said switch means adapted to be operated by said follower element; a follower engaging part on said movable element adapted to be engaged by the follower element to operate said switch means when said movable element has advanced less than said predetermined distance. The elements of the device are all mounted on a base plate 10 attached to the press. A support 12 carries an electric motor 14 which drives a disc 16 the motor shaft being attached to the disc at a point mid-way between its centre and periphery. Diametrically opposed to the location of the motor shaft in the disc is a dowel pin 18 which is received between the arms of a bifurcated fork 20 secured to a one-way drive disc 22 mounted at one end of a shaft 26 supported in a block 28. The one-way drive disc 22 has a plurality of sockets 32 opening upon a sleeve 24 each socket containing a spring-loaded ball 34 which only bind against the sleeve to effect the drive when the disc is rotated counterclockwise. At the other end of the shaft 24 is mounted a cam follower comprising a slidably mounted spring-loaded disc 36 provided with an eccentric pin 38 which co-operates with a cam disc 52 to move the disc 36 axially to operate adjustable switch means 44 to shut off the press and deenergize the motor 14. The cam disc 52 is driven by the stock being fed to the press e.g. intermittently, and so long as the stock or strip is being properly fed to the press there will be no displacement of the cam follower. The cam disc 52 is mounted on a shaft 54 carried by a block 56. Should the switch 44 not be connected to the motor 14 a stop block 66 on the disc 52 engages the pin 38 and prevents it from traversing the cam disc and restarting the press. In order that the cam will not be advanced too far ahead of the pin 38 in the feeding of a long strip to the press a segment-shaped stop 68 is adjustably secured to the periphery of the cam 52. The one-way drive disc 22 permits the pin 38 to be rotated by the cam 52 in advance of the motor drive without causing damage to the motor. The stock feed means for rotating the cam 52 comprises a roller 72 attached to a ratchet wheel 74. The strip 5 is engaged between the roller 72 and two support rollers 76 mounted on a spring-loaded pivoted arm 78. Laterally adjustable guide rollers 84 maintain the strip in a straight path. When the strip is exhausted a spring-loaded pawl 94 on the arm 78 engages in the ratchet wheel 74 and prevents rotation of the cam 52 whereupon the pin 38 engages the raised part of the cam and stops the press. The device includes thickness sensing means for stopping the press if the stock being fed is too thick. Such means include an upper roll 100 and a lower roll 102, Fig. 6. The upper roll, which is permitted only very limited rotation is secured to one end of a spring-loaded arm 112 the other end of the arm being provided with a pawl 126 for engaging the ratchet wheel 74. The lower roll 102 is freely rotatable on its shaft which is vertically adjustable to give the required spacing between the rolls. Both rolls are provided with a peripheral bead 118 to engage the stock. Should the thickness of the stock increase the increased friction between the rolls causes the upper roll to rotate and the pawl 126 to engage the ratchet to stop the press. A flat 128 is provided on the upper roll to permit the stock to continue to advance to the press until the press is shut off. Similar means may be provided for stopping the press should the thickness of the stock decrease.