WEB PROCESSING LINE & MODULES

Abstract: Modular web processing units may be physically and electrically assembled into clusters to perform various web processes (e.g. the production of paper forms such as invoices, checks, labels, etc.). Each module has a main process driver which is not directly coupled to a web drive mechanism. Rather, the web drive is program controlled so as to effect the desired web process at controlled displacement intervals along the web. Accordingly, a plurality of successive but different form lengths of depths can be accommodated as the web surface is sequentially processed. A system of such modules can be physically wheeled into position as individual units and electrically connected together by a suitable intermodule bus to rapidly configure a desired overall web finishing process. Examples of modules for unwinding web from a roll, for folding processed web, for printing and for perforation or cut-off are described. Each module has a mechanism driven by a motor for performing an action on the web, an encoder driven by the mechanism and a servo coupled to the motor and encoder, the servo being responsive to signals on the intermodule bus to control the speed of the motor so that the average velocity of the web through the module does not exceed the velocity of the web as it moves through the other modules of the line.

Description: This invention relates to module for printing on a web to be installed in a line of web processing modules all electrically connected together via an intermodule bus. Such line of modules preferably may be easily reconfigured to perform different overall web finishing functions of diverse types. This application concerns improvements to the apparatus and method of our earlier EP-A-0183336 EP-A-0225727. The contents of the specifications of both these earlier applications are hereby incorporated by reference. Elongated webs of paper product are often used to produce finished paper business forms of various types. For example, cheques, ledger sheets, statements of accounts, invoices, etc. often start out as large rolls of blank paper web. The web is then processed in many different ways to produce a finished form which may include partial perforations so as to permit easy separation of one form from the next or of one part of the form from other parts thereof. Numbering, imprinting, printing with bar codes, MICR printing, punching, gluing, placing, etc. processes are typically sequentially performed on the web to produce a finished roll or "pad" of web product. If the forms are designed for later utilisation in automated printing equipment, they typically include so-called tractor drive sprocket holes along the outside edges of the web (with associated partial perforations so as to permit such sprocket drive portion later to be detached). The forms may include multiple layers such as to result in carbon copies, chemically sensitised copies, or the like. Prior devices generally have been designed merely to repetitively perform only the same process at the same relative registered location(s) on each successively encountered single form depth dimension of the moving web. Thus they are not truly operator-programmable. In contrast, the above applications disclosed systems programmable so as to conveniently vary the relationship between process and web drives in accordance with an easily gauged functional relationship. For example, the programmable functions may be chosen to match the average web throughput of other modules (connected thereto only by slack loops and electrical connectors) and/or to effect successive different progressed form depths between successive process operations. It has been discovered that a considerable improvement (eg greatly increased flexibility in the finishing process, reduced set up time and decreased capital investment) can be realised by arranging an ensemble of modular units to effect a desired overall web finishing process -- and where the web drive within each module is related to its main process drive by a programmable electronic velocity or displacement "profile" and where all of the process drives operate in synchronism in response to a common electronic "drive shaft". Full advantage of the invention is best realised by an ensemble of interconnected modules so as to form an entire web finishing "line". For example, the modules can be grouped together in clusters so as to form an independent "piece" of production gear or to "speed follow" existing production equipment (arranged to supply, take-up or perform some intermediate process in conjunction with the assembled cluster of modules) and provide additional web processing capabilities. Microprocessor-based electrical controls provide a mechanically "decoupled" form of programmed motion control for the web drive with respect to the main process drive within each module. An electrical plug connected bus forms an umbilical cord to electrically interconnect the modules being utilised within a common "line". The bus connection permits each module's main process drive to be slaved to a common drive pulse source thus making it appear that all of the process drives are driven from a common drive shaft. It is important to ensure that the average velocity of the web passing through one module does not get out of step with the web passing through other modules. An object of the present invention is to provide a printing module for use in such a processing line of modules which keeps the web passing through the printing mechanism under tension while maintaining the average velocity of web passing through the module. Accordingly the invention provides a module for printing on a web to be installed in a line of web processing modules all electrically connected together via an intermodule bus, comprising a printing mechanism, a tractor upstream of the printing module, an encoder driven by the tractor to indicate the amount of web movement, a servo means coupled to the tractor encoder, a web drive mechanism downstream of the printing mechanism, a motor for driving both the printing mechanism and the web drive mechanism, an encoder driven by the web drive mechanism, the printing mechanism, the web drive motor and the encoder being coupled to the servo means, the servo means being coupled to the intermodule bus, the servo means being responsive to signals from the bus and from the encoders to control the speed of the web drive mechanism so that the average velocity of the web through the printing module substantially equals the velocity of the web as it issues from the previous module, characterised in that the tractor upstream of the printing mechanism is driven by the web, the web drive mechanism is an overspeed pull motor, and the module includes a braking means between the tractor and the printing mechanism for tensioning the web. One embodiment of printing module for inclusion in a line of web processing modules all electrically connected together via an intermodule bus will now be described, by way of example only, with reference to the accompanying drawings. The module is described and illustrated as included in a web processing line of the type described in EP-A- 0225727 and the description and drawings of that specification are referred to herein rather than repeated in full. The present figure is numbered Fig. 30 to follow on from Figures 1 to 29 of that specification and shows a diagram of a printing module. Figure 30 shows a system for operating a printing station (print engine) 3090. In this system a motor 3092 drives the print engine 3090 through which the web passes. However, the arriving web is first taken over and drives a tractor unit 3094. An encloder 3096 responds to the web and tractor movement, and supplies signals to a tractor servo 3098. Motor 3092 takes its commands from servo 3098. A set of S-wrap rollers 4000 is provided, under retarding effect of a hysteresis brake unit 4002. The brake is coupled to an operator interface circuit 4004, which is also coupled to a motor servo controller 4006. A further feature is the provision of an overspeed pull roller unit 4008, also driven by motor 3092. Unit 4008 drives an encoder 4010 which is coupled to servo controller 3098. The servos 3098 and 4006 are each coupled to the bus intermodule 3020. The tractor system 3094 is driven by the paper and serves two purposes: (1) it drives encoder 3096 to provide longitudinal position information to the control software, and (2) it guides the web laterally into the module. The sevo controller 3098 accepts form depth information transmitted from other modules in the cluster (there is no form depth operator interface on the module) and calculates an average paper velocity profile which exactly equals the average paper throughput of each of the other modules in the cluster. The tractor encoder, providing paper position feedback, is used to cause the main drive motor 3092 to run at the proper speed to match the cluster. Tension into the print engine nip is provided by the manually controlled hysteresis brake 4002. In this arrangement, if the web were to break between the print engine and the tractor, the encoder 3096 would stop and there would be a loss of feedback, causing the drive motor 3092 to run full speed. Because of this problem, the separate encoder 4010 is mounted directly in the module drive system, which provides feedback for the motor 3092 during the absence of paper from the upstream tractor system 3094. The two encoders are constantly monitored by servo controller 3098 to determine if a proper displacement is achieved by the encoder to indicate the presence of paper. Servo controller 3098 may contain a software algorithm which uses this information to decide which encoder should provide system position feedback.

Claims: 1. A module for printing on a web to be installed in a line of web processing modules all electrically connected together via an intermodule bus (3020), comprising a printing mechanism (3090), a tractor (3094) upstream of the printing module, an encoder (3096) driven by the tractor to indicate the amount of web movement, a servo means (3098) coupled to the tractor encoder, a web drive mechanism (4008) downstream of the printing mechanism, a motor (3092) for driving both the printing mechanism and the web drive mechanism, an encoder (4010) driven by the web drive mechanism, the printing mechanism (3090), the web drive motor (3092) and the encoder (4010) being coupled to the servo means (3098), the servo means being coupled to the intermodule bus, the servo means being responsive to signals from the bus and from the encoders to control the speed of the web drive mechanism so that the average velocity of the web through the printing module substantially equals the velocity of the web as it issues from the previous module, characterised in that the tractor (3094) upstream of the printing mechanism is driven by the web, the web drive mechanism (4008) is an overspeed pull motor, and the module includes a braking means (4000, 4002) between the tractor (3094) and the printing mechanism for tensioning the web. 2. A module according to claim 1 including a second servo mechanism (4006) arrange to regulate the braking means and also being coupled to the intermodule bus (3020). 3. A printing module according to claim 1 or claim 2 installed in a line of web processing modules characterised in that the information as to form depths is supplied by the intermodule bus from another module.

Inventors: STEIDEL, LEONARD R.
Applicants: MOORE BUSINESS FORMS, INC.
Application year: 1987
Main classification: B65H20
IPC codes: B65H20, B65H23, B65H45