Patent GB-330653-A (GB)
Title: Improvements relating to web tensioning apparatus
IPC: B65H23/08
Filed: 1929-01-19
Abstract: 330,653. Crabtree & Sons, Ltd., R. W., and Phythian, T. E. Jan. 19, 1929. Feeding webs.-In a rotary printing- press fed from a magazine roll stand, variation of the tension of the web is caused to move the roll stand automatically so as to effect a movement of the roll relatively to a brake and thus vary the braking effort to restore the tension of the web to normal. The brake comprises a belt b, Fig. 1, mounted on pulleys b<1>, b<2> and adapted to swing about the arms of the pulley b<1>. This belt is driven at a slightly lcwer speed than the web and engages the active roll c, the web from which passes to the press over guide rollers d, e, e<1> and a floating roller f. The roller f, Fig. 2, is supported by springs f<3> and rods f<4> adjustably engaging arms g fixed to a spindle g<1> carrying weighted arms n. The spindle of the guide roller e<1> carries a worm e<3> which drives, through a worm-wheel h<1>, a shaft h carrying a grooved cam h<2> engaging a roller h<3> on an arm h<4> guided on the shaft h. The arm h<4> passes freely through a swivel block h<5> carried by an arm i<1>, Figs. 2 and 3, on a shaft i. A spring h<5> is mounted on the arm h<4> between the block h<5> and a nut h<7> so that the shaft i is oscillated through a yielding connection. Fixed to the shaft i is a frame i carrying an axially slidable spindle k on which is mounted a pair of discs k', k<2> normally lying partly beneath the ends of plungers l<1>, l<2> which are connected together by a lever l. The plungers serve to operate switches m<1>, m<2> in the circuit of the reversible motor m which drives the roll stand a<1> through gearing m<5>, m<3>, m<4>. The axial movement of the spindle k is effected by an arm o fixed to the shaft g<1> and carrying a pin o<3> engaging a grooved member o<2> mounted on the spindle between springs o<1>. With the web tension normal, the parts are in the position shown in Fig. 2, the upward movement of the spindle being limited by the engagement of the discs k<1>, k<2> with the plungers, and the excess movement of the arm h<4> being taken up by the spring h<6>. Upon variation of the tension, the roller f rises or falls and causes a movement of the spindle k to the right or to the left. bringing one of the discs k<1>, k<2> fully under its plunger and the other disc clear of its plunger. Upon the next upward movement of the spindle k, one of the plungers is raised to operate the corresponding switch m<1>, m<2> and the motor m is driven in such a direction as to increase or decrease the braking effort of the belt b upon the roll c. To prevent rotation of the roll stand while in its loading position, a cam plate attached to the gear wheel m4 may be caused to operate a switch t to close the circuit of a solenoid r, Fig. 2, on the spindle k, the solenoid attracting both discs k<1>, k<2> and moving them into an inoperative position relatively to the plunger l<1>, l<2>. An arm p on the shaft g<1> is connected to a screwed rod q carrying a spring q<4> opposing the springs f<3>, and the rod q is geared to an electric motor q<3> controlled by a distant switch s, Fig. 1, so that the normal tension of the-web may be adjusted as required.