Web handling method and apparatus with pre-acceleration of web feed rolls

For continuously supplying web during both a normal operating period and a splicing period at a selected running speed to a web consuming machine, a web handling apparatus comprising:

• A) a main accumulator;
• B) splicing means;
• C) a first web station including
• i) first means rotatably supporting a first web roll for unwinding web therefrom,
• ii) first supplemental accumulator for storing web unwound from said first web roll during said splicing period and for supplying web from said first web roll to said splicing means, and
• iii) first means coupled with said first supporting means for rotating said first web roll at predetermined speeds;
• D) a second web station including
• i) second means rotatably supporting a second web roll for unwinding web therefrom,
• ii) second supplemental accumulator for storing web unwound from said second web roll during said splicing period, and for supplying web from said second web roll to said splicing means, and
• iii) second means coupled with said second supporting means for rotating said second web roll at pre-determined speeds;
• E) means for pulling web from one of said first and second web rolls along a web path with a substantially constant force sufficient to move said running web at said first speed;
• F) said splicing means being disposed along said web path between said first and second web stations and said pulling means, and being operable during said splicing period for splicing a trailing end of unwound web from one of said first and second web rolls with a leading end of unwound web from the other of said first and second web rolls, said splicing means making said splice while said unwound web from said one web roll travels at a selected minimum speed less than said running speed;
• G) said main accumulator being disposed along said web path between said splicing means and said pulling means for storing a pre-selected length of web during said normal operating period and providing at least a portion of the web stored therein during said splicing period, so as to store a maximum length of web during said normal operating period and a minimum length of web during said splicing period;
• H) wherein,
• i) during said normal operating period, web is supplied to said web consuming machine at said selected running speed from one of said first and second web rolls and, in order to substantially deplete the web stored therein, from the associated one of said first and second supplemental accumulators, and without depleting the web stored within said main accumulator, and
• ii) during said splicing period, web is supplied to said web-consuming machine at said selected running speed from said main accumulator;
• and
• I) means for causing the one of said first and second rotation means associated with the web roll providing the leading end of unwound web to the splicing means to begin accelerating that web roll prior to splicing and then continuing acceleration of that web roll to a speed in excess of the selected running speed in such manner as to attain the selected running speed earlier than would be the case if that web roll were not accelerated until the splice were made, and to replenish the web in said main accumulator in preparation for another splicing phase, wherein web that is unwound from said accelerating web roll prior to splicing is stored in the associated supplemental accumulator.

A web handling method for continuously supplying a running web to a web-consuming machine at a first speed and for splicing said running web to a ready web at a lower, second speed while continuing to supply said running web to said web-consuming machine at said first speed, said method comprising the steps of

• A) rotating a first roll of web, and supplying a leading end of said web at a selected running speed to a web-consuming machine;
• B) storing a length of said web from said first roll in a first accumulator;
• C) braking said first roll so as to slow a trailing end of said web to a selected minimum speed including zero;
• D) splicing the slowed trailing end of said first roll to a leading end of web of a second roll while said first roll is rotating at said minimum speed;
• E) during said braking and splicing steps, supplying at least a portion of said web stored in said first accumulator at said selected running speed to said web-consuming machine;
• F) beginning acceleration of said web from said second web supply before completing said splicing step, and continuing said acceleration to said selected running speed;
• G) storing, in a second accumulator, web unwound from said second web supply due to said acceleration;
• and
• H) after completion of said splice, supplying to said web-consuming machine said web stored in said second accumulator due to said acceleration.

While continuously supplying a web at a selected running speed to a web-consuming machine, a method of splicing a trailing end of web from a rotatably-supported first web roll to a leading end of web from a rotatably-supported second web roll at a selected minimum speed including zero, said method comprising the steps of:

• A) rotating said first web roll so as to unwind web therefrom at said selected running speed;
• B) passing said unwound web along a web path from said first web roll through a first web-storage means for storing a predetermined length of web and then to said web-consuming machine;
• said rotating step comprising the step of pulling the web from said first web roll by means disposed along said web path between said first web-storage means and said web-consuming machine;
• C) supplying the unwound web from said first web roll at said selected running speed to said web-consuming machine while substantially maintaining the length of web stored in said first web-storage means during non-splicing operation;
• D) braking the rotation of said first web roll so as to slow a trailing end of said unwound web therefrom to a selected minimum speed including zero;
• E) at a splicing location along said web path between said first web roll and said first web-storage means, splicing said slowed trailing end of said unwound web from said first web roll with a leading end of said second web roll;
• F) during said braking and splicing steps, supplying at least a portion of said web stored in said first storage means to said web-consuming machine so as to maintain the supply of web thereto at said selected running speed;
• G) accelerating said second web roll so as to unwind web therefrom before completing said splicing step, and continuing said acceleration until web unwinding therefrom achieves a speed in excess of said selected running speed so as to be able to replenish the web in said first storage means and to supply web from said second web roll to said web-consuming machine at said selected running speed;
• and
• H) in a second storage means disposed along a second web path between said second web roll and said splicing location, storing at least a portion of web unwound from said second web supply due to said acceleration while said splice is being performed.

A method of splicing a first web, drawn from a rotatably supported running roll and feeding into a first web accumulator serving web to a web consuming machine running at a substantially constant line speed, to the adherent leading edge margin of a second web wound on a rotatably supported ready roll, said method comprising the steps of

• braking said running roll until the speed of the first web entering the accumulator slows to a selected splicing speed;
• upon the first web reaching the selected speed, pressing together the leading edge margin of the second web and the first web ahead of the first web accumulator to splice the two webs;
• while the two webs are still pressed together, accelerating the ready roll and storing the second web let off said ready roll in a second web accumulator;
• severing the first web just behind the splice;
• relieving the pressing of the webs;
• continuing the acceleration of the ready roll after said relieving step until the second web attains a running speed at or near line speed, and subsequent to said relieving step substantially emptying the second web stored in the second web accumulator into the first web accumulator.

Splicing apparatus comprising

• a first web accumulator;
• means for rotatably supporting a first roll of running web;
• means for rotatably supporting a second roll of ready web, said ready web having an adherent leading end;
• means for guiding said running web from said first roll through said first web accumulator;
• means for drawing the running web from said first web accumulator at a substantially constant line speed;
• means for braking said first roll until the running web entering the first web accumulator slows to a selected splicing speed;
• means responsive to the attainment of said splicing speed for momentarily pressing the adherent leading end of the ready web and the running web together ahead of the first web accumulator to splice the two webs;
• means for accelerating the second roll while the two webs are still pressed together;
• a second web accumulator for storing the ready web let off the second roll while the two webs are pressed together;
• a knife for severing the running web just behind the splice, and
• means for stopping the acceleration of the second roll when the web from that roll attains a selected speed at or near said line speed.