Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G9/00—Other accessories for paper-making machines
  • D21G9/0063—Devices for threading a web tail through a paper-making machine

Definitions

• the invention relates to a method and device for conveying a tail.
• the method complies with the appended claim 1
• the device is of the type presented in the preamble of the appended claim 5.
• One known way to transfer the narrow tail in a controlled manner is to utilize suction belts driven at the threading speed.
• the air permeable suction belts form loops that travel via reversing rolls, the tail being sucked against the upper surfaces of the loops by means of a suction arranged inside each loop.
• Typical examples of tail threadings by means of suction belt loops are disclosed for instance in the US patents 3355349 and 4022366 and in the European patent 232689.
• the problem is that the travel of the tail is unstable before it enters the space between the ropes or belts, primarily due to forces in the lateral direction.
• the tail can be tightened against the rolls during the threading, wherein in diagonal threading the edge of the tail is tightened and the risk that the tail will break is increased.
• the amount of paper passed between the ropes or the belts is poorly controllable.
• the method according to the invention is primar- ily characterized in what will be presented in the characterizing part of the appended claim 1.
• the device according to the invention is characterized in what will be presented in the characterizing part of claim 5.
• the method according to the invention can be applied in all vacuum transfer belts.
• the threading of the tail is implemented at that stage when it is devoid of substantial tension in the machine direction, i.e. when the tail is slack in such a manner that it is not yet tightened against the rolls.
• the belt conveyor feeding the tail between the threading ropes or belts is transferred to a suitable position during threading. Negative pressure affects through the belt of the belt conveyor, said negative pressure keeping the tail in its place on the surface of the belt.
• the belt conveyor is turned automatically and at the correct moment during threading so that the belt conveyor guides the tail away from between the ropes or belts.
• the belt conveyor is turned with respect to the turning point advantageously in the beginning of the belt. Because the turning of the belt conveyor is conducted before the tail is tightened against the roll, the tail enters the space between the ropes or belts in a stable manner and the edge is not tightened under the forces that affect in the lateral direction.
• the method according to the invention can be applied in all vacuum transfer belts, in which the tail is passed on a vacuum belt between threading ropes or belts. In threading tests by a pilot machine, the threading conducted by means of the method according to the invention raised the percentage of success to 75%, whereas experiments show that when prior art methods are used, the percentage of success is 33%.
• the running speed in the test was 1 ,800 m/min.
• Fig. 1a shows the state of art in a side-view
• Fig. 1b shows the state of art in a top view
• Fig. 2a shows the method according to the invention in a side- view
• Figs. 2b to 2c show the method according to the invention in a top view.
• Figs. 1a to 1b show a method according to the state of art for threading a tail.
• the tail T is separated from a web unwound from a reel R.
• the tail T is tightened against the roll 1 , and travels in this tight state to the point 2 in which it is passed between the threading ropes or belts.
• the tail T is guided by a belt conveyor 3, on top of which the tail T is arranged to fasten itself by means of negative pressure affecting through the belt of the belt conveyor.
• the tail T travels in an angle with respect to the machine direction, wherein laterally loading forces are applied on the other edge of the same, said forces being capable of causing the breaking of the tail T.
• Figs. 2a to 2c show a method according to the invention for threading a tail.
• the tail T is separated from a web unwound from a reel R.
• the threading is conducted at that stage during the travel of the tail T when said tail is slackened and conveyed to the point 2 where it is passed between the threading ropes or belts.
• the tail T is guided by a belt conveyor 4, on top of which the tail T is arranged to fasten itself by means of negative pressure affecting through the belt of the belt conveyor.
• the belt conveyor comprises reversing rolls 4a and a belt 4b, which belt can e.g. be made of the wire material of the paper machine.
• the negative pressure can be arranged in such a manner that a suc- tion device is placed inside the suction belt loop, which device is connected to the lower surface of the belt and effects a holding suction through the air permeable suction belt.
• the suction device can be a vacuum box sealed against the lower surface of the belt, which is connected to the suction.
• the suction box can be divided into successive zones, or several suction boxes can be arranged successively, and these zones or suction boxes may contain negative pressures which can be adjusted separately.
• the tail T which is substantially strainless, i.e. slack, is arranged to travel to the point 2 in such a manner that during the travel of the tail T under the control of the belt conveyor 4, said tail T is transferred more to the longitudinal direction of the machine.
• Fig. 2c the lateral movement of the belt conveyor 4 is illustrated by means of an arrow M.
• the belt conveyors are typically located in an angle with respect to the longitudinal direction of the machine when the threading begins.
• the movement of the belt conveyor 4 in the direction of arrow M is arranged by turning the belt conveyor 4 with respect to a suitable turning point.
• the turning function effective at the turning point can be a bearing arrangement or the like.
• the motion of the belt conveyor is automatic, the timing is precise and relates to the threading sequence.
• the invention is not restricted to the description above, but it may vary within the scope of the claims.
• the main aspect of the invention is that the tail is conveyed on a belt conveyor, which can be moved in the width direction of the machine during threading by turning it around a suitable turning point.

Landscapes

• Paper (AREA)
• Replacement Of Web Rolls (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
• Advancing Webs (AREA)
• Steroid Compounds (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=8557837

Family Applications (1)

Country Status (6)

Family Cites Families (2)

• 2000
  • 2000-03-03 FI FI20000500A patent/FI20000500A0/fi unknown
• 2001
  • 2001-03-01 EP EP01913919A patent/EP1264044B1/fr not_active Expired - Lifetime
  • 2001-03-01 AT AT01913919T patent/ATE271159T1/de active
  • 2001-03-01 WO PCT/FI2001/000204 patent/WO2001065006A1/fr not_active Ceased
  • 2001-03-01 AU AU2001239332A patent/AU2001239332A1/en not_active Abandoned
  • 2001-03-01 DE DE2001604289 patent/DE60104289T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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