Phasing control system for web having variable repeat length portions

A method for controlling the phasing or repeat length portions of a moving web to an operating machine at an operating station along the web wherein the operating machine has a cyclically repeating operating cycle and is designed to perform the same operation at the same relative postion within each repeat length portion of the web passing through the operating station and wherein the web is of the type which is subject to minor variations in the length of the repeat length portions thereof, comprising:

• (a) providing register indicia on the web in associatiton with each repeat length;
• (b) sensing the passage of each register indicia at a sensing station located a predetermined distance of web travel upstream from an indicia registration point in said operating station associated with a predetermined, cyclically reoccurring operating machine state and generating a register indicia sensing signal indicative of the sensing of register indicia at said sensing station;
• (c) providing a web travel signal indicative of the distance of web travel;
• (d) determining the point in time at which a register indicia is coincident with said operating station registration point by determining the point in time at which the web travel distance occurring after the sensing of an indicia at said sensing station is equal to said predetermined web travel distance between said sensing station and said operating station registration point through the use of said sensing signal and said web travel signal and generating a web indicia registration signal having signal pulses indicative of said coincidence between a web register indicia and said operating station registration point;
• (e) continuously monitoring the relative cyclical state of said operating machine including monitoring the occurrence of a machine reference state which occurs at the time a register indicia is located in coincidence with said operating station reference point during proper registration of said web and said operating machine;
• (f) determining the web phasing error distance associated with each repeat length portion of the web by measuring the distance of web travel occurring between the occurrence of a registration signal pulse indicative of the point in time of coincidence between a register indicia and the operating station registration point, and the point in time of the occurrence of said machine reference state;
• (g) determining the length of each repeat length portion at a position upstream of said operating station by determining the distance of web travel occurring between a first sensed indicia and the next sensed indicia using said indicia sensing signal and said web travel signal;
• (h) determining the repeat length error distance associated with each repeat length portion of the web by comparing the measured repeat length distance thereof to a predetermined design repeat length value and calculating the difference;
• (i) determining the total web travel adjustment needed for proper phasing of a repeat length portion with the operating machine when the repeat length portion is positioned one repeat length upstream of the operating station by adding the repeat length error distance associated with the immediately preceding repeat length portion to the phasing error distance associated with the immediately preceding repeat length portion;
• (j) adjusting the speed of the web relative the speed of the operating machine to provide said web travel adjustment.

Apparatus for controlling the phasing of repeat length portions of a moving web to an operating machine at an operating station along the web wherein the operating machine has a repeating operating cycle and is designed to perform the same operation on each repeat length portion of the web pasing through the operating station and wherein the web is of the type which is subject to minor variations in the length of the repeat length portions thereof, comprising:

• (a) register indicia means associated with each repeat length portion of the web positioned at a substantially identical location within each repeat length portion of the web for sensing by a register indicia sensing means for indicating the relative position of an associated repeat length portion;
• (b) register indicia sensing means positioned at a sensing station along the web at a preselected distance of web travel upstream of the operating station for sensing the passage of said register indicia at said sensing station and for providing a register indicia sensing signal indicative of the occurrence of said machine reference position;
• (c) web travel monitoring means operatively associated with the web for providing a web travel signal indicative of web travel distance;
• (d) machine reference position sensing means for sensing the occurrence of a cyclically repeating preselected reference position of said operating machine, said reference position being selected to occur in a predetemined relationship with the occurrence of the coincidence of a web reference indicia and a preselected reference point in said machine operating station when the associated web repeat length portion is in phase with said operating machine, and for providing a machine position reference signal indicative thereof;
• (e) operating machine movement sensing means for providing a machine movement signal indicative of the relative cyclical machine movement of said operating machine;
• (f) data processing means for receiving and processing said web register indicia sensing signal, said web travel signal, said machine reference position signal, and said machine movement signal and for generating a control signal for controlling the relative rate of movement between said web and said operating machine based on said processing of signals for placing each repeat length portion of the web in proper registry with said operating machine wherein said data processing means comprises;
• web repeat length calculating means for calculating the length of each repeat length portion of the web prior to its passage through the operating station;
• repeat length error determining means for comparing said calculated length of each repeat length portion to a predetermined, constant, design repeat length value for determining the relative repeat length error occurring in each repeat length portion;
• register indicia reference signal generating means for generating a signal indicative of the passage of a register indicia past said preselected reference point in said operating station which is located at a predetermined distance of web travel downstream of said indicia sensing means;
• phasing error determining means for comparing said register indicia reference signal to said machine position reference signal for measuring the phasing error between a web repeat length portion and the operating machine during each operating machine cycle;
• error summing means for summing a determined phasing error associated with the repeat length portion located at the operating station with a determined repeat length error associated with the repeat length portion located at the operating station for determining an initial total error value for the repeat length portion immediately upstream of the operation station which is representative of the distance by which said immediately upstream repeat length portion is out of phase with said operating machine at a point in time when it is positioned approximately one repeat length upstream of said operating station;
• wherein the control signal generated by said data processing means is based upon said determined total error value associated with the repeat length portion immediately upstream of the operating station.

Apparatus for controlling the phasing of repeat length portions of a moving web to an operating machine at an operating station along the web wherein the operating machine has a repeating operating cycle and is designed to perform the same operation on each repeat length portion of the web passing through the operating station and wherein the web is of the type which is subject to numerous minor variations in length of the repeat length portions thereof from a design repeat length, comprising:

• (a) instantaneous phasing error measuring means for measuring the phasing error between the operating machine and a web repeat length portion upon which an operation is performed which exists at the occurrence of a preselected, cyclically repeating, reference position of the operating machine;
• (b) repeat length error measuring means for measuring the deviation of the actual length of a repeat length portion of the web from the design repeat length at a position upstream of said operating station;
• (c) total phasing deviation determining means for adding the mesured phasing error of the repeat length portion currently located at the operating station and the measured repeat length error of the repeat length portion currently located at the operating station for determining the total distance by which the next succeeding repeat length portion of the web is out of phase with the operating machine at a time when the next succeeding repeat length portion is positioned approximately one repeat length distance of web travel upstream of the machine operating station;
• (d) phasing correction response means for making a phasing correction during the period when said next succeeding repeat length portion is traversing the last repeat length distance of web travel upstream of said operating station by variation in the relative speed between the operating machine and the web in response to said determined sum of said instantaneous phasing error and associated repeat length error for placing said next succeeding repeat length portion in registry with said operating machine.