Cutting – Processes
Reexamination Certificate
1999-01-08
2001-06-19
Rada, Rinaldi I. (Department: 3724)
Cutting
Processes
C083S076100, C083S557000, C083S575000, C310S316010
Reexamination Certificate
active
06247388
ABSTRACT:
This invention is concerned particularly with the control of apparatus for cutting at regular intervals a web such as, for example, used for joining cigarettes to filters in a filter attachment machine. Web cutting in this context involves cooperation at regular intervals between two members at least one of which preferably rotates. Cutting may, for example, be achieved by a crushing action between a knife on one member and an anvil on the other member. Alternatively, cutting may be achieved ultrasonically, for example as described in our PCT patent application WO 94/14583 (case 3643).
In both crush cutting and ultrasonic cutting it is desirable to control the relative positions of the two members which cooperate to perform each cut in order to achieve a sufficient but not excessive cutting force. The present invention is concerned particularly with an automatic control system for use particularly in such web cutting arrangements.
Apparatus according to this invention for periodically applying a controllable force to a moving part (for example a web of paper to be cut) comprises a force-applying member, and means for producing a control electrical signal indicative of the force applied by the force-applying member and for controlling the force applying member so as to control the force applied by it to the moving part, the control signal being produced with the aid of a lock-in amplifier to which is applied a force-responsive electrical signal together with a reference signal, whereby any noise element in the control signal is eliminated or reduced by the lock-in amplifier.
By this means, despite the noise which almost inevitably accompanies the signals from a sensor, for example in this context, the average cutting force of the force generated at each cut (for example) can be obtained to enable the position of one of the cutting members to be adjusted in order to achieve a desired level of cutting force. For example, in apparatus for cutting a filter attachment web (commonly termed “cork paper”), the cutting members can be set at positions such that, in the absence of the web, there would be merely light contact between the cutting members; thus the presence of the web during use results in a significant but not excessive force being applied sufficient to cut the web, whether this is achieved by an ultrasonically driven cutting member or by means of a simple crush cutting operation as used conventionally in connection with cork cutting in a filter attachment machine.
Lock-in amplifiers are known per se and are commercially available. For example, reference is directed to a book entitled “The Art of Electronics” by Paul Horowitz and Winfield Hill, published by Cambridge University Press. In the second edition section 15.15 contains a general description of “Lock-in detection” and some uses thereof. An example of a commercially available lock-in amplifier which may be used in carrying out the present invention is that made by Analog Devices, of 1 Technology Way, P.O. Box 9106, Norwood, Mass. 02062-9106, USA and identified as their AD630 product.
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Carter David Christopher Miller
Collett Peter Nicholas
Antonelli Terry Stout & Kraus LLP
Molins PLC
Rada Rinaldi I.
Tran Kim Ngoc
LandOfFree
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