Claims
- 1. Apparatus for handling a web of material fed from a roll on a shaft, which comprises:
- means for supporting the shaft;
- means for sensing the tension of the web;
- an infeed roller for feeding the web, said infeed roller having a rotational speed that varies in response to the tension sensing means;
- a nipping roller for pressing the web against the infeed roller to prevent slippage;
- a roll contacting belt for contacting the outer surface of the roll and aiding in rotating the roll;
- means responsive to said tension sensing means for driving the belt;
- sprocket means coupled to the shaft;
- positive drive means for engaging said sprocket means for variably controlling the rotation of the roll, with movement of said positive drive means being responsive to said tension sensing means;
- means for operating said roll contacting belt to control the rotation of the roll and thus the tension of the web when the roll is larger than a selected amount; and
- means for disengaging said roll contacting belt from the roll and for operating the positive drive means once the roll decreases to said selected amount.
- 2. Apparatus as described in claim 1, including means for transmitting the rotational speed of the infeed roller to the belt driving means so that the speed of the web at the infeed roller and the speed of the roll contacting belt are substantially matched.
- 3. Apparatus as described in claim 1, including means for moving said roll contacting belt in and out of contact with the outer surface of the roll.
- 4. Apparatus as described in claim 1, including clutch means for increasing the speed of said roll contacting belt gradually after it has first contacted the surface of the roll.
- 5. Apparatus as described in claim 1, in which said means for driving the belt comprises a clutch pulley, a pulley keyed to said infeed roller, and a belt coupling said infeed roller pulley to said clutch pulley.
- 6. Apparatus as described in claim 1, in which said positive drive means comprises an endless chain.
- 7. Apparatus for handling a web of material fed from a roll on a shaft, which comprises:
- means for supporting a shaft:
- means for sensing the tension of the web;
- an infeed roller for feeding the web, said infeed roller having a rotational speed that varies in response to the tension sensing means;
- a nipping roller for pressing the web against the infeed roller to prevent slippage;
- a roll contacting belt for contacting the outer surface of the roll and aiding in rotating the roll;
- means for moving said roll contacting belt in and out of contact with the outer surface of the roll;
- clutch means for increasing the speed of said roll contacting belt gradually after it has first contacted the surface of the roll;
- means responsive to said tension sensing means for driving the belt;
- sprocket means coupled to the shaft;
- positive drive means for engaging said sprocket means for variably controlling the rotation of the roll, with movement of said positive drive means being responsive to said tension sensing means;
- means for operating said roll contacting belt to control the rotation of the roll and thus the tension of the web when the roll is larger than a selected amount;
- means for disengaging said roll contacting belt from the roll and for operating the positive drive means once the roll decreases to said selected amount; and
- means for transmitting the rotational speed of the infeed roller to the belt driving means so that the speed of the web at the infeed roller and the speed of the roll contacting belt are substantially matched.
- 8. Apparatus as described in claim 7, in which said positive drive means comprises an endless chain.
- 9. Apparatus for handling a web of material fed from a roll on a shaft, which comprises:
- means for supporting the shaft;
- means for sensing the tension of the web;
- an infeed roller for feeding the web, said infeed roller having a rotational speed that varies in response to the tension sensing means;
- a nipping roller for pressing the web against the infeed roller to prevent slippage;
- a roll contacting belt for contacting the outer surface of the roll and aiding in rotating the roll;
- means responsive to said tension sensing means for driving the belt;
- rigid means coupled to and rotatable with the shaft;
- rotation control means for engaging said rigid means for variably controlling the rotation of the roll, with movement of said rotation control means being responsive to said tension sensing means;
- means for operating said roll contacting belt to control the rotation of the roll and thus the tension of the web when the roll is larger than a selected amount; and
- means for disengaging said roll contacting belt from the roll and for operating said rotation control means in cooperation with said rigid means once the roll decreases to said selected amount.
RELATED APPLICATION
This application is a continuation-in-part of U.S. application Ser. No. 918,481, filed Oct. 14, 1986.
This invention concerns a system for handling a web of material from a roll, and, in the illustrative embodiment, a system for supplying a continuous, uninterrupted web of material. Although the illustrative embodiment concerns a paper web that is fed to a web printing system, it is to be understood that the present invention has more general applications.
In Curran, et al. U.S. Pat. No. 4,173,314, an apparatus is disclosed for continuously supplying web material to a web printer. The web material is fed from a first roll that is supported in a feed position and, when the first roll is near depletion, the leading end of a second roll is adhesively connected to the web of the first roll with that web then being severed. A pair of parallel belts are employed for rotating both the forward and rearward rolls in order for both rolls to achieve the same speed for the connecting and severing operations. We have found that this prior art system does not work properly because the surface speeds of the first and second rolls are not the same when the rolls are of a different diameter. In addition, the paper from a roll tends to telescope when the roll diameter is relatively small and the wrap is not tight. If the belts apply a high pressure against the loose wrap, the chance of telescoping is even greater. If the belt tension is reduced in order to alleviate the telescoping problem, there may be slippage of the belts. There may also be a tracking problem because the belts are so long in that they are used to drive both of the rolls, and one of the belts may jump the pulleys.
Thus the prior art web supply apparatus discussed above has several disadvantages including problems in maintaining tension on the very long belts required, problems with belt tracking, tension upsets caused by the relative motion between the belts and the center line of the roll, and speed mismatches caused by differences in the distances that the belts contact the rolls or "wrap" which prevent an exact speed match between the expiring roll and the new roll.
It is desirable to have a system in which a continuous supply of web material may be supplied, with the disadvantages discussed above being alleviated. We have discovered an apparatus for supplying a continuous, uninterrupted web of material that does not require one or more belts for rotating both the forward and rearward rolls and thus does not have the problems described above.
Another problem that is found on high speed automatic machines, and web presses in particular, is the inherent delay between the time of a signal for a mechanism to activate and the time that the mechanism's function is completed. For example, the delay between the time that a signal is given for the knife to cut the expired web after it has been attached to the web from the new roll and the time that the cutting is actually completed may cause certain problems. In a high speed automatic splicer, it is necessary that the residual paper that remains attached to the new roll after the splice from the expired roll be kept as short as possible in order to reduce the probability of jamming the folder. The length of the glued area is approximately 15 inches and the overall length from the beginning of the paste to where the expired web was severed should be no more than 20 inches. Unfortunately, the delay time in the operation of the knife is typically equivalent to over two feet of paper. It is, therefore, necessary that the signal for the knife to cut the expired web be given at a time such that, irrespective of the delay in the knife firing, the cut will occur at the proper place. This anticipation of the signal time must be proportional to the speed of the machine with the anticipation being near zero at extremely low speeds and the full amount of the delay at high speeds. Previously, means to accomplish this anticipation have resulted in complex electronic devices using analog principles which have an inherent tendency to vary with temperatures, time, supply voltage, etc.
We have invented a system using timing means which are extremely accurate at any speed likely to be encountered on a printing press. Our invention anticipates the signal time but does not require complex electronic devices as required by prior art systems.
In accordance with the present invention, an apparatus is provided for handling a web of material fed from a roll on a shaft. The apparatus includes means for supporting the shaft and means for sensing the tension of the web. An infeed roller is provided for feeding the web, with the infeed roller having a rotational speed that varies in response to the tension sensing means. A nipping roller is provided for pressing the web against the infeed roller to prevent slippage. A roll contacting belt contacts the outer surface of the roll and aids in rotating the roll. The roll contacting belt is driven in response to the tension sensing means. A sprocket is connected to the shaft and positive drive means are provided for engaging the sprocket in order to variably control the rotation of the roll. Movement of the positive drive means is responsive the tension sensing means. The roll contacting belt is operated to control the rotation of the roll and thus the tension of the web when the roll is larger than a selected amount. Once the roll decreases to the selected amount, the predrive belt is disengaged from the roll and the positive drive means operates to control the rotation of the roll.
In the illustrative embodiments, means are provided for transmitting the rotational speed of the infeed roller to the roll contacting belt driving means so that the speed of the web at the infeed roller and the speed of the roll contacting belt are matched. The means for sensing the tension of the web comprise a floating roller, a variable speed pulley for controlling the speed of the infeed roller, and a tension belt coupled to the variable speed pulley. Means are provided for varying the tension infeed roller, and a tension belt coupled to the variable speed pulley. Means are provided for varying the tension of the tension belt to vary the speed of the variable speed pulley in response to pivotal movement of the floating roller. The floating roller is in direct contact with the web and is operative to pivot in response to variable web tension.
In one embodiment, the positive drive means is controlled in response to pivoting of the floating roller. The apparatus includes a cam that rotates in response to pivoting of the floating roller and the positive drive means is operated by a pneumatic cylinder. A pressure regulating valve is controlled by the cam and the pneumatic cylinder is operated in response to the pressure regulating valve.
Means are provided for sensing the tension of the web being fed. An infeed roller is provided for feeding the web, with the infeed roller having a rotational speed that varies in response to the tension sensing means. A nipping roller presses the web against the infeed roller to prevent slippage.
A predrive belt is provided for contacting the outer surface of the second roll and for aiding in rotating the second roll. The predrive belt is driven in response to the tension sensing means.
First brake drum means are coupled to the first shaft and second brake drum means are coupled to the second shaft. Means are provided for variably engaging the first brake drum means for variably braking the rotation of the first roll, with movement of the brake drum engaging means being responsive to the tension sensing means. Means are provided for operating the predrive belt to control the rotation of the second roll. In this manner, rotation of the first roll and thus the tension of the web from the first roll is controlled by the brake drum engaging means and the rotation of the second roll is controlled by the predrive belt when the predrive belt contacts the outer surface of the second roll.
In the illustrative embodiment, means are provided for transmitting the rotational speed of the infeed roller to the predrive belt driving means so that the speed of the web at the infeed roller and the speed of the predrive belt are matched, thereby matching the speed of the second web material with the speed of the first web material. Means are provided for connecting the second web to the first web and also means are provided for severing the first web after such connection.
In one illustrative embodiment, the brake drum engaging means comprises a linear brake surface and a curved brake surface downstream of the linear brake surface. The predrive belt is operated to control rotation of the second roll and thus aid in controlling the tension of the web when the second roll is larger than a selected amount, the predrive belt is disengaged from the second roll and the brake drum engaging means is operated. In accordance with the invention, the second shaft is moved adjacent the linear brake surface and then to the curved brake surface. In this manner, tension of the web is first controlled by movement of the linear brake surface with respect to the brake drum and thereafter is controlled by movement of the curved brake shoe with respect to the brake drum.
In accordance with the present invention, a method is provided for activating a device for operating on a moving workpiece. For example, the moving workpiece may be a rotating roll of web material and the device may be a cutting device for cutting the web material. First, the inherent time delay between an activation signal and the time required for the device to operate on the moving workpiece is determined. A selected position of the workpiece is sensed. Index means are provided for indexing the travel of the workpiece. The index means are counted in a first count mode for a predetermined time after sensing the selected position. Thereafter, the index means are counted in a second count mode. An activation signal is provided when the predetermined number of counts has occurred. The first count mode comprises a function of the number of counts for each count of the second count mode.
In the illustrative embodiment, the predetermined time is substantially equal to the inherent time delay between the activation signal and the time required for the device to operate on the moving workpiece. The first count mode is twice the number of counts for each count of the second count mode.
A more detailed explanation of the invention is provided in the following description and claims, and is illustrated in the accompanying drawings.
US Referenced Citations (3)
Continuation in Parts (1)
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Number |
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918481 |
Oct 1986 |
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Patent Grant
4729522
