Laser curtain edge tracking systems for papermaking machines

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.

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.

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.