Improved system for controlling a web property profiling apparatus

Abstract

 Disclosed is a control system for controlling a web property profiling apparatus. The profiling apparatus includes a plurality of actuators (36) which are spaced across the web profiling apparatus. Each actuator (36) is controlled by an actuator driver (34) which is connected to a group of one or more actuators. A controller (40) sends a multiplexed control signal to the drivers (34) over a single coaxial link. The actuator drivers (34) demultiplex the transmitted signal, and the appropriate actuator driver corresponding to the location where the web property is to be altered accepts the signal and converts the signal to an analog form for operating the connected actuator(s) (36). Each actuator driver (34) is surrounded by a housing which environmentally protects the said driver. Such a housing would typically include an inner thin layer (54) of a high thermal conductivity material and an outer layer (55) of low conductivity material. The two layers are spaced apart from each other to form a chamber (56) therebetween and a fluid passes through the chamber to remove incoming and generated heat from the actuator drivers.

Description

BACKGROUND OF THE INVENTION

[0001] This invention relates to papermaking and more particularly to a system for controlling an apparatus utilized for profiling a web.

[0002] In the production of paper, or any such material produced in a similar web form, it is often desirable to control certain web properties during the production process. The control of web properties such as moisture percent, dry weight, caliper (thickness) and surface finish (such as gloss) is typically executed by means of a series of actuators spaced equally across the width of the web production machine, the design and location of which are dependent upon the web being controlled.

[0003] Such actuators perform their intended function by selectively altering the environment to which the web is exposed during production. Examples include the application of a suitable fluid to the web or a machine component in contact with the web, the direct dimensional alteration of a machine component in contact with the web, exposure of the web or a machine component in contact with the web to a suitable radiative or electromagnetic field, or exposure of the web to a machine component which is selectively cooled or heated in a positional sense. In these examples, the actuators are equally spaced across the web production machine, are co-linear in the cross machine direction, and are, or may be, effectively controlled by electrical or electronic means.

[0004] Often the primary energy source for the actuators is electrical power, in which case the actuator power supply and control signal are usually one and the same. In other cases the control signal is used to indirectly employ an actuator "energy source" other than electrical power (such as steam, water, etc.).

[0005] The control requirements of such systems are such that each actuator must be provided with a suitable electric signal. As this is typically accomplished by the hardwire connection of each and every actuator to a suitable remote control station, a plethora of hard-wire links is required. For example, for a 300 inch wide paper machine having actuators spaced on 3 inch intervals across the machine, one hundred separate circuits are needed.

[0006] Referring to Figs. 1 and 2, prior art control systems are shown. The Fig. 1 control system is a closed loop system with a power panel, and the Fig. 2 system is an open loop system with a power panel. In these systems, the actuator driver boards 12 are located in a separate off-machine panel 14 from which individual hardwire connections 16 extend to each one of the machine actuators 18. The main computer control panel 20 is connected to a sheet sensor 22 in the closed loop system. An operator interface panel 24 is provided to allow an operator to control the system manually. In the closed loop system, such an interface panel is not absolutely necessary, but it may be provided to enable a control back up function for manual interfacing. When such an interface panel 24 is included in the prior art closed loop systems, the input lines 26 and the output lines 28 may be of any conventional design.

[0007] Referring now to Fig. 8, an example incorporating a cross-machine profiling apparatus 60 is shown which utilizes a prior art control system. The apparatus 60 includes an array of cross machine actuators 18 which spray controlled amounts of water 62 onto the web 64. In prior art control systems, a separate wire or pair of wires 66 are connected between each actuator 18 and the off-machine controller 68.

[0008] As can be appreciated, the installation and trouble shooting of such systems can be rather time consuming and costly. In addition, in certain cases the dangers associated with high power circuitry are exaggerated by the number and length of such circuits.

[0009] It is therefore a principal object of the present invention to provide a web profiling apparatus control system which eliminates the need for complicated hardwire circuitry.

[0010] Another object of the present invention is thus to provide a web profiling apparatus control system which reduces system installation time, simplifies maintenance and trouble shooting by using a "clean" building-block approach, and eliminates the dangers associated with multiple, long, high power electrical connections.

SUMMARY OF THE INVENTION

[0011] In the present invention, the need for complicated hard-wire circuitry is eliminated by multiplexing the signals. In a preferred embodiment, the actuator control signals are conveyed to the controlled apparatus by means of a serial communications, single, coaxial cable link. On-machine actuator driver boards located in close proximity to related actuators decipher the serially transferred control protocol, accept messages intended for their respective cross-machine position, and convert such control signals into the analog form required for local actuator control. The actuators are driven directly or indirectly by electrical power, with power being admitted to the actuator in the required format by means of digital-to-analog conversion at the driver-board level.

[0012] In one embodiment, a complete system includes an off-machine "operator" panel which accepts either manual inputs by an operator, or automatic inputs as part of a closed loop control system. This operator-panel enables the transformation of control data from a manual-input format, or external computer system protocol, to the customized protocol utilized by the on-machine driver-boards. The operator-panel sends serial data strings consisting of driver board location addresses and actuator control status directives to the on-machine apparatus via the coaxial link. The data strings are analyzed by "receivers" on the driver-boards, with each driver-board acting only upon messages intended for its specific use. The coaxial link is designed as a two-way "send/receive" communication link, requiring that each destination driver-board acknowledge message receipt, thereby enabling the operator panel to monitor the driver-board performance and signal failure conditions if they should occur.

[0013] One major feature of the present invention is the provision of a "smart" web property profiling device, which, through the use of on-machine digital to analog converters, is capable of communicating directly with a central computer controller. Although a typical aparatus would possess one on-machine driver-board per every four or eight actuators (depending upon the actuator type), direct computer control of on-machine profiling system actuators is possible, and such direct computer control would, eliminate the need for multiple hard wire connections thereby essentially creating a "smart" actuator.

[0014] These and other objects and features of the present invention will be more fully understood from the following detailed description which should be read in light of the accompanying drawings in which corresponding reference numerals refer to corresponding parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 

Fig. 1 is a schematic view of a prior art profiling apparatus utilizing closed-loop control system;

Fig. 2 is a schematic viw of a prior art profiling apparatus utilizing an open-loop control system;

Fig. 3 is a schematic view of a profiling apparatus closed-loop control system of the present invention;

Fig. 4 is a schematic view of a profiling apparatus open-loop control system of the present invention;

Fig. 5 is a schematic view of the preferred embodiment of an on-machine driver board of the system of Fig. 3 or 4;

Fig. 6 is a schematic view of the heat transfer characteristics of the on-machine actuator driver of the system of Fig. 3 or 4;

Fig. 7 is a simplified plan view, partly in section, of the enclosure for an on-machine actuator driver of the system of Fig. 3 or 4;

Fig. 7a is a sectional view of the enclosed taken along lines A-A of Fig. 7;

Fig. 8 is a diagrammatic view of the cross-machine profiling apparatus utilizing a prior art system;

Fig. 9 is a diagrammatic view of a cross-machine profiling apparatus utilizing the control system of the present invention as shown in Fig. 3 or 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Referring to Figs. 3 and 4, the improved profiling apparatus control system 30 of the present invention, herein referred to as the "smart profiling system", includes an off-machine operator interface panel 32 and an array of on-machine driver-boards 34. Unlike the prior art control systems where the actuator driver-boards 12 are located in a separate off-machine "power-panel" from the actuators 18, the actuator driver-boards 34 of the control system 30 of the present invention are located on-machine in close priximity to the actuators 36 which they are intended to control. As shown in Fig. 5, the actuator driver-boards 34 combine with the actuators 36 to effectively provide a cross machine series of "smart-actuators" 38 which can be controlled in a multiplexed solid state manner.

[0017] Fig. 5 shows the single cable input connections to the plurality of actuators 36. The actuators 36 are connected through the driver boards 34. A coaxial T-connector 37 connects the line from the driver boards 34 to the single coaxial control cable 72. Each of the driver boards is also connected to a single common power supply 74.

[0018] A closed loop system of the present invention as shown in Fig. 3 includes a main computer control panel 40 and a sheet sensor 42. The operator interface panel 32 is not necessary in a closed-loop system of the prior art, but if included, it may provide a control backup function for manual interfacing. In the present invention, however, the operator interface panel 32 is designed to provide the customized output protocol, through a single coaxial link 44 required for the efficient control of the on-machine driver-boards 34. As a result, the operator interface panal 32 is an important component of the smart profiling system 10.

[0019] Referring to Fig. 9, a cross machine profiling apparatus 70, similar to the apparatus shown in Fig. 8, is shown which includes an array of cross-machine actuators 36 which for example may spray controlled amounts of water 62 onto the web 64. Unlike the prior art system of Fig. 8 in which a separate wire or pair of wires 66 is connected between each actuator 18 and the off-machine controller 68, the system of Fig. 9 includes one coaxial control link 72 (single cable) and one 110 volt (or other) power bus 74 to connect the entire apparatus 70 with the driver-boards 34 to enable the individual control of each actuator 36.

[0020] In the environment in which the smart profiling systems 10 are utilized, temperature and moisture conditions impose a restrictive design criteria with respect to the on-machine driver boards 34. For this reason, the driver boards 34 of the present invention are packaged to maintain the on-machine driver boards 34 at a suitable operating temperature, while insuring that exposure to moisture is eliminated. As shown in Fig. 6, external environmental heat represented by arrow 46 and heat represented by arrow 48 which is generated within the driver board 34 are removed by a stream of cooling water represented by arrow 50.

[0021] As detailed in Figs. 7a and 7b, the circuitry 52 of the driver board 34 is "potted" within a thin layer 54 of high thermal conductivity plastic. The thin layer 54 provides insulation from moisture and enables a suitable heat dissipation rate. A second layer 55 of low thermal conductivity plastic is cast about the thin layer 54 so as to provide an internal water-jacket chamber 56. The low thermal conductivity outer plastic layer 55 reduces the heat influx from the environment while water or other cooling fluid 50 flowing through the internal water jacket 56 at a suitable flow rate, removes incoming and generated heat 46, 48 to maintain an adequate heat balance and circuitry 52 operating temperature. Water 50 is supplied to, and removed from, the water jacket 20 through potted inlet and outlet fittings 57, preferably of a quick disconnect, check valve type. The coaxial control 58 and 110 volt (or other) power 59 inputs are also potted. These two inputs also are preferably a quick disconnect type fitting. The analog actuator outputs 60 utilized to power and drive the actuators 36 are also potted and are preferably of a quick disconnect design.

[0022] It should be appreciated that any such mechanical packaging approach which insures the adequate control of the driver-board environment would be suitable, and would not detract from the main spirit of the invention, as relates to the unique provision of a "smart" profiling system.

[0023] While the foregoing invention has been described with reference to its peferred embodiments, various alterations and modifications will occur to those skilled in the art. All such variations and modifications are intended to fall within the scope of the appended claims. Furthermore, the invention should not be limited to any particular actuators or apparatus.

Claims

1. A control system for controlling a web property profiling apparatus, said system comprising:
a plurality of actuators for selectively altering an environment of a web to which said actuators are exposed, said plurality of actuators being spaced across the web profiling apparatus;
a plurality of actuator drivers for controlling said actuators, each of said plurality of drivers being connected to one or more of said plurality of actuators;
control means for selectively signalling actuator drivers to activate connected actuators;
a single coaxial link for linking said control means to each of said plurality of actuator drivers.

2. The control system of claim 1 said plurality of actuator drivers are located in close proximity to said connected actuators on said web property profiling apparatus.

3. The control system of claim 1 wherein said control means transmits a multiplexed signal to said plurality of actuator drivers over said single coaxial link.

4. The control system of claim 3 wherein said actuator drivers demultiplex said multiplexed signal, said actuator drivers further comprising means for accepting demultiplexed signals directed to its connected actuator.

5. The control system of claim 4 wherein said actuator drivers further comprise means for converting said accepted demultiplexed signals into an analog form to control said connected actuators.

6. The control system of claim 1 further comprising a housing surrounding said actuator drivers to protect said actuator drivers from moisture while maintaining said actuator drivers at a suitable operating temperature.

7. The control system of claim 6 wherein said housing comprises:
a first inner housing comprising a thin layer of high thermal conductivity material, said first inner housing insulating said actuator drivers from moisture and enabling an acceptable heat dissipation rate;
a second outer housing comprising a layer of low thermal conductivity material, said second outer housing being spaced from said first inner housing so as to form a sealed chamber therebetween, said chamber being capable of receiving a fluid to remove incoming and generated heat.

8. The control system for controlling a web property profiling apparatus, said system comprising:
a plurality of actuators for selectively altering an enviornment of a web to which said actuators are exposed, said plurality of actuators being spaced across the web property profiling apparatus;
a plurality of actuator drivers for controlling said actuators, each of said plurality of drivers being connected to one of said plurality of actuators, said actuator drivers being surrounded by a housing for protecting said actuator drivers from moisture while maintaining said actuator drivers at a suitable operating temperature;
control means for selectively signaling actuator drivers to activate connected actuators;
a single co-axial link for linking said control means to each of said plurality of actuator drivers.

9. The control system of claim 8 wherein said housing comprises:
a first inner housing comprising a thin layer of high thermal conductivity material, said first inner housing insulating said actuator drivers from moisture and enabling an acceptable heat dissipation rate;
a second outer housing comprising a layer of low thermal conductivity material, said second outer housing being spaced from said first inner housing so as to form a sealed chamber therebetween, said chamber being capable of receiving a fluid to remove incoming and generated heat.

10. The control system of claim 8 said plurality of actuator drivers are located in close proximity to said connected actuators on said web property profiling apparatus.

11. The control system of claim 8 wherein said control means transmit a multiplexed signal to said plurality of actuator drivers over said single coaxial link.

12. The control system of claim 10 wherein said actuator drivers demultiplex said multiplexed signal, said actuator drivers further comprising means for accepting demultiplexed signals directed to its connected actuator.

13. The control system of claim 11 wherein said driver actuators further comprise means for converting said accepted demultiplexed signals into an analog form to control said connected actuator.

14. An actuator driver for controlling the operation of actuators of a web production machine which alters a web property profile, said actuator drivers comprising a housing for surrounding and protecting said actuator drivers from moisture while maintaining said actuator drivers at a suitable operating temperature.

15. The actuator drivers of claim 14 wherein said housing comprises:
a first inner housing comprising a thin layer of high thermal conductivity material, said first inner housing insulating said actuator drivers from moisture and enabling an acceptable heat dissipation rate;
a second outer housing comprising a layer of low thermal conductivity material, said second outer housing being spaced from said first inner housing so as to form a sealed chamber therebetween, said chamber being capable of receiving a fluid to remove incoming and generated heat.

16. The actuator drivers of claim 15 further comprising inlet and outlet conduits through said housing, said conduits extending from outside said housing to said actuator driver through said first inner housing and said second outer housing, and conduits being potted to maintain the seal of said sealed chamber.

Drawing