Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
  • D01G25/00—Lap-forming devices not integral with machines specified above

Definitions

• the present invention relates to an improved distribution unit to be used in dry forming of web material, the distribution unit including one or more screen pipes into which a fibre material intended for forming a web is blown, the fibres penetrating through jackets of the screen pipes in order to be layered onto a wire, and the screen pipe(s) being arranged to extend transversely over the wire; and a rotatable brush roller arranged inside each screen pipe in the axial direction thereof. More particularly, the present invention relates to a distribution unit providing improved distribution of fibre by altering the airflow within the screen pipe.
• Distribution units are known from Finnish Patent 66,948 and U.S. Patent 4,352,649, hereby incorporated by reference.
• the Finnish patent describes the basic structure of a distribution unit typically applied in dry forming of sheet material.
• the distribution unit generally called a former, includes screen pipes as described above placed preferably in pairs in order to make a fibre flow travel in opposite directions over the wire in the cross direction thereof.
• the primary reason for such positioning of the pipes is that in practice it is virtually impossible to make a fibre flow blown only in one direction over the wire to be deposited evenly onto the wire in the cross direction thereof so as to provide an even cross direction profile of a web to be produced.
• a web's cross direction profile can be made considerably more even.
• the variation in the web thickness in the cross direction thereof should be minimal.
• An acceptable deviation from a target thickness is typically ⁇ 5%.
• an object of the invention is to provide a distribution unit which is to be used in dry forming of web material and which facilitates formation of a more even cross direction profile of the web.
• a distribution unit according to the invention which is characterized in that it further includes a blade wheel provided inside each screen pipe near the end that is opposite to the end where the fibre material is blown into the pipe, the blade wheel being arranged to blow in a direction opposite to the direction of flow of the fibre material.
• a basic idea of the invention is that the flow of fibres inside a screen pipe is slowed down by a flow that is opposite to the fibre flow. This produces a more even cross direction profile, apparently particularly since more fibre material than previously can thus be layered onto the margin of the web where the blade wheel is located.
• screen pipes are placed in pairs so as to provide opposite flow directions for the fibre material in the pipes, more fibres than previously can also be made to accumulate onto the other margin of the web, which results in a more even total profile of the web.
• a typical web profile comprised less fibres on the margins than in the middle of the web.
• the blade wheel is most preferably arranged on the shaft of the brush roller to rotate together with the roller.
• the blade wheel can also be fastened to a shaft, which is separate from the shaft of the brush roller and is rotatable with respect to the end surface of the screen pipe.
• This separate shaft is provided with an actuator arranged to rotate the shaft.
• the speed of rotation of the blade wheel can be adjusted independently of the rotational velocity of the brush roller.
• the speed of rotation of the brush roller is typically adjustable, but if a blade wheel provided in the roller rotates together with the roller, the structure of the blade wheel essentially determines the kind of reverse flow it produces.
• the blade wheel could be provided with adjustable blades so that the flow it produces could be adjusted at least to some extent independently of the speed of rotation of the brush roller.
• the screen pipes are arranged in the distribution unit in pairs so that the fibre material flows in opposite directions in screen pipes forming a pair.
• the figure shows the basic structure of the distribution unit according to the invention. It shows two screen pipes 1 arranged to extend transversely across a wire (not shown in the figure).
• the screen pipes 1 are arranged in a pair so that the fibre material in the pipes flows in opposite directions of flow A. This is achieved by blowing a fibre material flow 3 into the pipes via feed pipes 7 arranged at opposite ends of the screen pipes.
• the feed pipes direct substantially axial flows of fibre material in an air-fluidized state into the screen pipes.
• Screen jackets 2 of the screen pipes 1 are arranged rotatably around their axes in a manner known per se.
• the screen pipes also include brush rollers 4 arranged inside the pipes in a conventional manner also disclosed in Finnish Patent 66,948.
• the purpose of the brush rollers is to clean the jacket surfaces 2 of the screen pipes 1 and to improve the penetration of fibres through the jackets 2.
• the structure of the brush rollers is conventional and known for example from the aforementioned Finnish Patent.
• a blade wheel 5 is arranged inside the screen pipe 1 at the end opposite to the end where the fibres are input.
• the purpose of the blade wheel is to slow down the fibre flow 3 inside the screen pipe 1.
• a slower flow of fibres especially at the end of the screen pipe having the blade wheel enables fibres to be discharged through the jackets more evenly than previously along the entire length of the screen. This positive effect is most visible at the end of the screen pipe having the blade wheel.
• the blade wheel provided in the other screen pipe slows down the flow and enables fibre matenal to be layered also onto the other margin of the web matenal to be formed This provides a more even cross direction profile of the web than previously along the entire width thereof
• the blade wheel is arranged on the shaft
• Adjustment alternatives can be further improved by providing the blade wheel 5 with adjustable blades
• the airflow volume and pressure created by the blade wheel can be adjusted by varying the onentation of the blades even without changing the rate of rotation of the blade wheel.
• Such a blade wheel provided with adjustable blades would be particularly useful when arranged on the shaft of the brush roller to rotate with it
• the blades of the wheel could be set specifically for each type of fibre matenal, for example, when the matenal is changed
• Another possible alternative is to provide a blade wheel having a separate shaft
• An actuator and adjustable blades to further increase the number of adjustment alternatives
• an alternate source of airflow may be provided
• compressed air generated remotely may be provided v ia an air hose, to direct an airflow counter to fibre flow 3.
• the volume and pressure of the airflow may be adjusted as necessary, depending upon the source of compressed air.
• the distnbution unit according to the invention is descnbed above by means of only one illustrative embodiment. It should therefore be understood that it can be modified to some extent without deviating from the basic idea of the invention where a fibre flow inside a screen pipe is slowed down by means of blowing that is opposite in direction to the fibre flow
• the structure of the screen pipe and the components thereof, such as the brush roller can vary similarly as in the pnor art distnbution units.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Nonwoven Fabrics (AREA)
• Paper (AREA)
• Treatment Of Fiber Materials (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=8554385

Family Applications (1)

Country Status (10)

Families Citing this family (3)

Citations (2)

Family Cites Families (4)

• 1999
  • 1999-04-09 FI FI990784A patent/FI105837B/fi active
• 2000
  • 2000-04-07 AU AU43411/00A patent/AU4341100A/en not_active Abandoned
  • 2000-04-07 NZ NZ513937A patent/NZ513937A/xx not_active Application Discontinuation
  • 2000-04-07 JP JP2000610663A patent/JP2002541350A/ja not_active Withdrawn
  • 2000-04-07 WO PCT/US2000/009690 patent/WO2000061354A1/en not_active Application Discontinuation
  • 2000-04-07 KR KR1020017012682A patent/KR20020005656A/ko not_active Application Discontinuation
  • 2000-04-07 BR BR0010779-4A patent/BR0010779A/pt not_active Application Discontinuation
  • 2000-04-07 EP EP00923253A patent/EP1177089A4/en not_active Withdrawn
  • 2000-04-07 CA CA002367503A patent/CA2367503A1/en not_active Abandoned
  • 2000-04-07 CN CN00806078A patent/CN1346307A/zh active Pending

Patent Citations (2)

Non-Patent Citations (1)

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