Laser curtain edge tracking systems for papermaking machines

• US 5,554,262 A
• Filed: 07/11/1994
• Issued: 09/10/1996
• Est. Priority Date: 07/11/1994
• Status: Expired due to Fees

• Current Assignee: Geschmay Corp. (Albany International Corporation)
• Original Assignee: Wangner Systems Corp (Albany International Corporation)
• Inventors: Turner, John S.
• Primary Examiner(s): Czaja, Donald E.
• Assistant Examiner(s): Fortuna, Jose A.
• Application Number:
  US08/272,808
• Time in Patent Office: 792 Days
• Field of Search: 162/263, 162/252, 162/262, 162/273, 162/272, 162/198, 162/199, 242/417.3, 242/418.1, 242/419.1, 356/375, 356/376, 356/385, 356/386, 356/387, 250/561, 250/548, 271/226, 226/20, 226/77, 226/88, 226/100
• US Class Current: 162/198
• CPC Class Codes: D21F 1/365 for controlling the lateral position of the screen

Abstract

An edge tracking apparatus for maintaining a continuous circulating papermaking fabric in an aligned position as it moves through a papermaking machine. The edge tracking apparatus includes a pivotally mounted guide roll and a laser scanner. The laser scanner, which produces a laser screen, is positioned relative to an edge of the papermaking fabric so that the edge bisects the laser screen. A controller is connected with the laser scanner. The controller acts to receive signals from the laser scanner in response to transverse movement of the edge of the papermaking fabric and to convert those signals into control signals which activate a drive in the steering apparatus. The drive shifts the longitudinal position of the guide roll causing it to steer the papermaking fabric back into its aligned position. A recording unit is also connected with the controller and is controlled to plot the position of the edge during operation of the papermaking machine.

Claims

1. An edge tracking apparatus in combination with a papermaking machine having a continuous papermaking fabric circulating therethrough, said tracking apparatus comprising:

a guide roll support structure pivotally mounting a guide roll for rotation about a longitudinal axis;

a drive connected with said support structure, said drive being operative to move said support structure to pivot said guide roll;

supporting said continuous papermaking fabric with said guide roll with said fabric contacting said guide roll with a wrap of between 25° and

75°

;

a laser scanner arranged to emit a laser screen, said laser screen having a uniform width and being positioned to be interrupted at a selected point substantially midway along said width by a longitudinal edge of said papermaking fabric said laser scanner being operative to continuously monitor the lateral position of said edge during movement of said papermaking fabric through said papermaking machine;

a controller connected with said drive and with said laser scanner, said controller being adapted to receive electrical signals from said laser scanner in response to any movement of said longitudinal fabric edge away from said selected point and to produce control signals in response to said received electrical signals which activate said drive to move said support structure to pivot said guide roll;

wherein

lateral movement of said fabric edge transversely of said laser screen during circulation of said fabric through said papermaking machine activates said tracking apparatus to cause said guide roll to maintain said longitudinal edge along said selected point.

2. The apparatus of claim 1 wherein said laser scanner includes a transmitter which emits a parallel laser screen and a receiver which receives said parallel laser screen;

whereby any change in the quantity of light received by said receiver causes said scanner to produce a corresponding control output.

3. The apparatus of claim 1 wherein said laser scanner includes a transmitter for transmitting said laser screen and a receiver for receiving said laser screen, said laser scanner being operative to initiate movement of said guide roll in a first direction upon said receiver sensing an increase in light quantity and to initiate movement of said guide roll in an opposite second direction upon sensing a decrease in light quantity.

4. The apparatus of claim 1 wherein said papermaking machine includes a paper forming section arranged between front and rear ends thereof, said continuous papermaking fabric moves from said front end over said papermaking section, to said rear end and returns to said front end along a path beneath said forming section, means mounting said laser scanner along said return path of said papermaking fabric.

5. The apparatus of claim 1 wherein said papermaking machine includes a papermaking section arranged between front and rear ends thereof, said continuous papermaking fabric runs from said front end over said paper forming section, to said rear end and returns to said front end along a path beneath said forming section, said support structure mounting said guide roll along said return path of said papermaking fabric.

6. The apparatus of claim 1 wherein said papermaking machine includes a front end, a rear end and a paper forming section arranged between said front and rear ends, said continuous papermaking fabric runs from said front end over said forming section to said rear end and returns to said front end along a path beneath said forming section, said support structure mounting said guide roll at one of said front and rear ends of said papermaking machine.

7. The apparatus of claim 1 wherein said papermaking machine includes idler rolls, a front end, a rear end and a paper forming section arranged between said front and rear ends, said continuous papermaking fabric moves from said front end over said forming section, to said rear end and returns to said front end along a path beneath said forming section,

said idler rolls being mounted along said return path and acting to support and tension said continuous papermaking fabric.

8. The apparatus of claim 7 wherein said guide roll is arranged intermediate of said idler rolls.

9. The apparatus of claim 1 wherein said guide roll support structure comprises a mounting structure pivotally mounting one end of said guide roll and a longitudinally moveable mounting structure mounting an opposite end of said guide roll, said drive connecting with said longitudinally moveable mounting structure;

whereby,

activation of said drive longitudinally displaces said longitudinally moveable mounting structure.

10. An edge tracking apparatus in combination with a papermaking machine including a frame having a continuous papermaking fabric circulating therethrough, said tracking apparatus comprising:

a laser scanner adapted to constantly sense the lateral position of said papermaking fabric, said laser scanner having a transmitting arm which delivers a laser screen of pre-selected volume said screen having parallel opposed edges and a receiving arm which receives said laser screen and produces an electrical signal in response to the volume of screen received;

a mount mounting said laser scanner with said frame adjacent a longitudinal edge of said fabric with said edge being arranged transverse of said screen and intermediate said parallel edges to interrupt a portion of said screen;

a controller connected with said laser scanner, said controller being operative to produce control signals responsive to electrical signals from said laser scanner;

a steering apparatus, said steering apparatus being connected with and receiving said control signals from said controller, said steering apparatus being operative to maintain said papermaking fabric aligned with said desired lateral position in response to said control signals;

whereby,

movement of said edge of as little as 0.0001 mm away from a desired lateral position alters sufficiently the volume of said laser screen sensed by said receiving arm to cause said receiving arm to produce and send an electrical signal to said controller indicative of said movement, said controller producing a control signal in response to said electrical signal which activate said steering apparatus.

11. The apparatus of claim 01 further comprising a recording apparatus, means connecting said recording apparatus with said controller, said recording apparatus being operative to plot the lateral position of said edge of said papermaking fabric during operation of said papermaking machine.

12. An edge tracking apparatus in combination with a papermaking machine, said papermaking machine including a plurality rotating support, idler and drive rolls acting to support and circulate a continuous papermaking fabric through said papermaking machine, said support, idler and drive rolls each having an axis of rotation transverse the direction of movement of said continuous paper forming fabric;

wherein said tracking apparatus comprises;

an edge sensor comprising a laser scanner having a transmitting arm which delivers a laser screen of pre-selected volume and a receiving arm which receives said laser screen and produces electrical signals in response to the volume of screen received, said laser scanner being arranged adjacent a longitudinal edge of said papermaking fabric, said laser scanner being operative to continuously monitor said moving edge of said papermaking fabric to detect lateral position changes of said longitudinal edge relative to a desired lateral position during movement of said continuous papermaking fabric through said papermaking machine, said transmitting arm generating laser screens of varying volume depending upon the position of said longitudinal edge relative to said desired lateral position;

a guide roll over which said papermaking fabric passes;

a guide roll mounting structure mounting said guide roll for angular displacement and a drive selectively operable to displace said guide roll relative to said mounting structure;

a recording unit operative to record the linear position of said longitudinal edge during movement of said continuous paper forming fabric through said papermaking machine;

a controller, said controller being operative to receive said electrical signals generated by said receiving arm and to produce control signals operative to activate said drive to displace said guide roll to steer said longitudinal edge through minute longitudinal positions and into alignment with said desired lateral position, said controller further producing second control signals in response to said electrical signals to activate said recording unit to graphically plot the positions of said longitudinal edge relative to said desired lateral position during movement of said paper forming fabric through said papermaking machine;

wherein,

said edge tracking apparatus acts to simultaneously maintain said edge aligned with said desired lateral position and plot the position of said edge during operation of said papermaking machine.

13. The apparatus of claim 12 wherein said edge sensor is a laser scanner which emits a laser screen having parallel edges and said desired lateral position locates said longitudinal edge along an intermediate point between said edges.

14. An edge tracking apparatus in combination with a papermaking machine, said papermaking machine including a plurality of rotating support, idler and drive rolls acting to support and circulate a continuous paper forming fabric through said papermaking machine, said support, idler and drive rolls each having an axis of rotation transverse the direction of movement of said continuous paper forming fabric, wherein said tracking apparatus comprises:

a laser scanner adapted to constantly sense the lateral position of said papermaking fabric, said laser scanner having a transmitting arm which delivers a laser screen of preselected volume and a receiving arm which receives said laser screen and produces an electrical signal in response to the volume of screen received;

a recording unit, said recording unit being operative to plot the linear position of said longitudinal edge during movement of said continuous papermaking fabric through said papermaking machine;

a controller, said controller being operative to receive said electrical signals from said laser scanner said controller being operative to produce and send control signals responsible to said electrical signals which are operative to control said recording unit;

whereby,

said tracking apparatus records transverse movements of said longitudinal edge during movement of said papermaking fabric through said papermaking machine.