초록 ▼

An apparatus and method for minimizing web cinching during unwinding of rolls of web material of indeterminate length. The position of the float frame or support member (36) of an accumulator (32) for the web is monitored and a proportional signal is sent to a comparator (52) which produces an incre

An apparatus and method for minimizing web cinching during unwinding of rolls of web material of indeterminate length. The position of the float frame or support member (36) of an accumulator (32) for the web is monitored and a proportional signal is sent to a comparator (52) which produces an increasing output signal as the float frame opens in the accumulator and a decreasing signal as the float frame closes. The output signal is fed to an integrator (66) which produces a gradually increasing or decreasing contol signal for a voltage to pressure transducer (70) which operates a pneumatic brake (74).

대표청구항 ▼

Apparatus for intermittently, cyclically feeding a web of material of indeterminate length, comprising: a shaft mounted for rotation; means for mounting a roll of said web material for rotation with said shaft; means for braking said shaft; means for receiving a web from said roll and accumulating a

Apparatus for intermittently, cyclically feeding a web of material of indeterminate length, comprising: a shaft mounted for rotation; means for mounting a roll of said web material for rotation with said shaft; means for braking said shaft; means for receiving a web from said roll and accumulating a variable length of said web, said means for receiving and accumulating comprising: a frame; a first at least one guide roller for said web supported by said frame; a support member; means for permitting said support member to move relative to said frame toward and away from said first guide roller between a minimum brake force zone close to said first guide roller and a maximum brake force zone spaced from said first guide roller; and a second at least one guide roller arranged on said support member, whereby said web can be threaded alternately around said first and second guide rollers as said web passes through said means for receiving and accumulating; means for intermittently, cyclically withdrawing said web from said means for receiving and accumulating; means for sensing the position of said support member relative to said frame and producing a signal; and means responsive to said signal (a) for applying said means for braking with sufficient, gradually increasing brake force as said support member moves past each of a plurality of levels away from said first guide roller as demand drops from said means for withdrawing and (b) for releasing said means for braking with sufficient, gradually decreasing brake force as said support member moves past each of said plurality of levels toward said first guide roller as demand increases from said means for withdrawing, wherein said means for applying and releasing applies no break force in a first range of movement of said support member; gradually increases said brake force as said support member moves away from said first guide roller through a second range of movement of said support member until a first preselected maximum brake force is reached; maintains said first preselected maximum brake force for the remainder of said second range; and gradually increases said brake force for the remainder of said second range; and gradually increases said brake force beyond the preselected maximum brake force of the preceding range of movement, as said support member moves away from said first guide roller through successive ranges of movement of said support member until further preselected maximum brake forces are reached and maintained for the remainder of each successive range, to prevent cinching of said web on said roll as said roll accelerates and decelerates during said intermittent, cyclic withdrawing, while said support member assumes a variable position from said minimum brake force zone to said maximum brake force zone at the end of each cycle of said means for withdrawing.