A twin-wire former for a paper machine which can produce paper of good formation over a wide range of basis weight and at a speed of wide variation essentially consisting of a top wire and a bottom wire. The bottom wire with a wet material thereon substantially horizontally travels. The top wire approaches the material from above and travels downward together with the bottom wire on the circumference of a supporting member provided in the loop of the bottom wire while pressing the material between the pair of wires. At the position of a force roll provided in the loop of the top wire, the pair of wires commence travelling upwardly through a suction box to a couch roll, where the pair of wires separate from each other. To adjust the wire contacting angle of the supporting member, and hence, to improve the formation of paper, each of a water receiver, the force roll and suction boxes and made movable.
A web former for a paper machine having a lower-wire loop which forms an initial single-wire part of a dewatering zone. The former also includes a top-wire unit which includes an upper wire which forms a twin-wire dewatering zone together with the lower wire. The former also includes a first forming roll in a direction of web travel that is provided with an open hollow face and is fitted inside the upper-wire loop. The twin-wire forming zone begins in conjunction with the first forming roll. There is a forming shoe inside the lower-wire loop which is provided with a curved deck that guides the lower-wire loop. The former includes a second forming roll fitted inside the upper wire loop and situated after the forming shoe. A device for collecting water is provided in the former and operates without any external suction source, with dewatering being based upon kinetic energy of water that is being removed and/or upon gravity.
A spindle apparatus comprises a rotary body and at least a pair of magnetic bearings for levitating the rotary body by magnetic forces. A combined motor and magnetic bearing device is disposed between the magnetic bearings for imparting a rotational torque to the rotary body and for positionally controlling the rotary body by magnetic forces. A control circuit outputs and exciting current to the magnetic bearings and the combined motor and magnetic bearing device and for makes an adjustment of the exciting current of the magnetic bearing and the combined motor and magnetic bearing device to hold the rotary body afloat in a predetermined position.
In a method for forming a sheet from a fiber-water suspension, the fiber-water suspension is supplied on a traveling bottom wire at a first zone thereof to dewater the fiber-water suspension. Subsequently, the suspension is introduced between the bottom wire at a second zone and a top wire, and dewatering is effected. The sheet is further caused to travel around a sheet-forming roll while keeping the sheet in contact therewith by the bottom wire at a third zone thereof, and reformation of the sheet is carried out. Finally, the sheet on the bottom wire is caused to travel up to a fourth zone thereof to effect a further dewatering with a fourth dewatering device disposed adjacent to the bottom wire at the fourth zone thereof, whereby a final stage of sheet formation is carried out. An apparatus for carrying out the above method is also disclosed.
The invention relates to a wet end section of a twin wire paper machine. Each wire forms a wire loop. The wires are led together along a vertical, rising, common path, which starts at a wedge shaped feed nip at the bottom of the common path. The nip is formed by the two wires and is defined by a forming cylinder arranged in the loop of the inner wire. Inside the other outer wire, there is a fixed curved surface or outer surface having a center of curvature which lies on one side of the rising common wire path. A further curved inner surface which follows the outer surface along the wire path is provided on a doctor blade carrier or pivotable crossbeam located inside the loop of the inner wire. This is followed by a suction roll arranged in the loop of the outer wire. The length of the further inner surface is shorter than the length of the outer surface.
All of the essential operating parts for adding a top former assembly to a new Fourdrinier paper machine or for converting an existing Fourdrinier paper machine into a top former are carried by a supplemental frame assembly which can be mounted on the main Fourdrinier frame with minimal modification of the latter except the addition of simple parts for securing the supplemental frame assembly on top of the main frame. The primary operating parts of the top wire assembly are a hollow foraminous roll and a top wire deflector which cooperate to collect and deliver liquid expressed through the top wire into a receptacle that is carried by the supplemental frame assembly, and special provision is made for utilizing the top wire deflector to correct for irregularities in the cross machine profile of the paper sheet as it is being formed. Provision is also made for operating the resulting top former in roll former mode, blade former mode, or a combination roll and blade former modes.
