Fig. 1 is a plan view of a section of the spiral-type material which forms the base or carrier for the long nip press belt of the invention;
Fig. 2 is a schematic side elevation view showing the manner in which the long nip press belt of the invention is constructed;
Fig. 3 is a partial longitudinal section view through a portion of the long nip press belt of the invention constructed as in Fig. 2;
Fig. 4 is a view similar to Fig. 2, showing an alternative system for constructing a long nip press belt according to the invention;
Fig. 5 is a partial longitudinal section view through a portion of the long nip press belt of the invention constructed as in Fig. 4;
Fig. 6 is a schematic side elevation view of a long nip press in which the belt of the invention is employed; and
Fig. 7 is a schematic side elevation view of an alternative form of a long nip press in which the belt of the invention is employed.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 illustrates a section of a spiral-type base orcarrier 10 which forms a part of the long nip press belt of the invention. The construction ofbase 10 is representatively illustrated in Gauthier U.S. Patent 4,567,077, the disclosure of which is incorporated by reference. This patent discloses use of the spiral-type material as a papermaking fabric which directly supports the web.

Base 10 is constructed of oppositely oriented axially extending spirals, shown at 12, 14.Spirals 12 are oriented in one direction, e.g. with their upper portions being inclined leftwardly, andspirals 14 are oriented oppositely, e.g. with their upper portions inclined to the right betweenspirals 12.

Spirals

12 and 14 extend along parallel longitudinal axes. Referring to Figs. 3 and 5,

spirals

12 and 14 define longitudinally extending

internal passages

16, 18, respectively.

Spirals

12 and 14 are arranged to overlap each other, so that the end portions of

internal spaces

16, 18 overlap.Connector rods 20 extend through the overlapping portions of spiral

internal spaces

16, 18, to connect

spirals

12 and 14 into a continuous mat.

Construction of a spiral structure as shown in Fig. 1 and described above is known in the art.

Referring to Fig. 2,base 10 is constructed into an endless belt according to conventional technology, and is positioned about a pair of

rolls

22, 24. One of

rolls

22, 24 is driven so as to provide movement of the top run ofbase 10 in a left-to-right direction.

A urethane coating apparatus, schematically shown at 26, is positioned over the upper run ofbase 10, and includes anozzle 28 which deposits a coating of urethane, shown at 30, ontobase 10. Astationary box 32, defining a planar upper surface, is located belownozzle 28, and the upper run ofbase 10 extends through a space between the upper surface ofbox 32 andnozzle 28, with the lower surface ofbase 10 engaging the upper surface ofbox 32.

Urethane coating 30 is applied tobase 10 bynozzle 28 in a substantially uniform thickness throughout the width ofbase 10. When applied tobase 10, the urethane material is in a substantially liquid state, and functions to flow into and completely fill

passages

16, 18 of

spirals

12, 14, respectively, to a depth such that the lower extent ofurethane coating 30 is coextensive with the lower surface ofbase 10.

Rolls

22, 24 are operated at a speed such thaturethane coating 30 has set and hardened sufficiently when discharged from the upper surface ofbox 32 to form an integral, self-supporting sheet or mass withbase 10 embedded therein. This process of applyingurethane coating 30 tobase 10 is continued whilebase 10 is moved by

rolls

22, 24 until the entire extent ofbase 10 is coated with coating 30 to thereby form an integral,endless urethane belt 33 reinforced bybase 10 embedded therewithin.

As noted previously,urethane coating 30 defines a lower surface, shown at 34, which is coextensive with the lower surface ofbase 10.Coating 30 further defines anupper surface 36 spaced above the upper surface ofbase 10. Representatively,base 10 has a thickness of approximately 0.08 inches, and coating 30 has a thickness of approximately 0.13 inches, leavingupper surface 36 of coating 30 approximately 0.05 inches above the upper surface ofbase 10. This thickness ofcoating 30 has been found to provide sufficient flexibility and strength to belt 33 to withstand use in a long nip press environment.

After coating 30 has been applied tobase 10,upper surface 36 ofcoating 30 may be ground and polished in accordance with conventional technology.

Fig. 4 illustrates another arrangement for forming a long nip press belt according to the invention. In this arrangement,box 32 is positioned below the upper run of a pouringbelt 38, which extends the entire width ofbase 10. Pouringbelt 38 is trained about a series ofrolls 40, one of which is driven to provide movement of pouringbelt 38 belowbase 10 at the same rate of speed at whichbase 10 travels between

rollers

22, 24.Base 10 and pouringbelt 38 are arranged such that a space, shown at 42, is disposed between the lower surface ofbase 10 and the upper surface ofbelt 38.

Aurethane coating 44 is applied to base 10 fromnozzle 28.Coating 44 again functions to completely fill

spaces

16, 18 in

spirals

12, 14, respectively ofbase 10, and to pass throughbase 10 andspace 42 into engagement with the upper surface of pouringbelt 38. This results in a longnip press belt 45, as illustrated in Fig. 5.Belt 45 is constructed substantially identically to belt 33 of Fig. 3 in which base 10 is embedded within and reinforcesurethane coating 44. In this embodiment, however,urethane coating 44 defines alower surface 46 which is spaced below the lower surface ofbase 10. As in the embodiment of Fig. 3, theupper surface 48 ofbelt 45 is disposed above the upper surface ofbase 10. Representatively, coating 44 has a thickness of approximately 0.17 inches, andbase 10 again has a thickness of approximately 0.08 inches.Upper surface 48 ofbelt 45 is disposed approximately 0.05 inches above the upper surface ofbase 10, andlower surface 48 ofcoating 44 is disposed approximately 0.04 inches below the lower surface ofbase 10. This thickness ofcoating 44 is sufficient to provide adequate strength and flexibility to belt 45 for use in a long nip press environment.

Rollers 40 are configured and arranged relative tonozzle 28 to provide support for coating 44 while it sets and hardens after application fromnozzle 28 so that, when coating 44 andbase 10 are discharged from therightwardmost roller 40, coating 44 forms a self-supporting sheet or mass withbase 10 embedded therewithin. The process of applyingcoating 44 tobase 10 is continued whilebase 10 is moved by

rolls

22, 24 until the entire extent ofbase 10 is coated withcoating 44.

Coatings

30, 44 may be any satisfactory elastomer such as conventional urethane as is available from Uniroyal Chemical Corp. under its designation Adiprene Ribbon Flow. Alternatively, any satisfactory elastomer such as is known to those of ordinary skill in the art could be employed to form

coatings

30, 44.

Coatings

30, 44 are impervious and flexible, and have a sufficient hardness to withstand use in a long nip press environment. Representatively,

coatings

30, 44 have a hardness of approximately 95 (shore A).

Referring to Fig. 6,

belts

33, 45 are adapted for use in a long nip press, shown generally at 50. The press nip includes acylindrical press roll 52, anarcuate pressure shoe 54, and

belts

33, 45 constructed as described above disposed againstpressure shoe 54 betweenshoe 54 androll 52. Arod 56 is pivotably mounted topressure shoe 54 for applying the desired pressure toshoe 54.

A papermaker'swet press fabric 58 supports afibrous web 60, being processed into a paper sheet.Fabric 58 andweb 60 pass throughlong nip press 50 betweenroll 52 and the belt, such as 33, 45, for extracting water fromweb 60. The construction and arrangement of the elements ofpress 50 are conventional in the art.

Belt 33 is arranged inpress 50 such that itsupper surface 36 is disposed againstpressure shoe 54, in order to provide maximum wear resistance to belt 33. In this construction, the lower surface ofbase 10 bears againstfabric 58.Belt 45 is preferably oriented with itsupper surface 48 bearing against supportingfabric 58 and itslower surface 46 bearing againstpressure shoe 54. The presence of urethane material betweenlower surface 46 and the lower surface ofbase 10 provides resistance to wear imparted to belt 45 frompressure shoe 54.Belt 45 may have itsupper surface 48 grooved, drilled or otherwise patterned, as is known in the art, to provide additional void volume for water removal during processing.

Fig. 7 illustrates an alternative construction of along nip press 62 in which

belts

33, 45 constructed according to the invention are employed. As inpress 50 of Fig. 6,press 62 includes acylindrical press roll 64, anarcuate pressure shoe 66, and

belts

33, 45 constructed as described above disposed againstpressure shoe 66 betweenshoe 66 androll 64. Arod 68 is pivotably mounted topressure shoe 66 for applying the desired pressure toshoe 66.

Afibrous web 70, being processed into a paper sheet, is disposed between a pair of papermaker's

wet press fabrics

72, 74.

Fabrics

72, 74,web 70 and the belt, such as 33, 45, move upwardly through the nip betweenroll 64 andpressure shoe 66, for extracting water fromweb 70. The construction and arrangement of the elements ofpress 62 are conventional in the art.

Belts

33, 45 are arranged inpress 62 in the same manner as described above with respect topress 50.

Base 10 is oriented within

belts

33, 45 such thatconnector rods 20, and the longitudinal axes of

spirals

12, 14, extend perpendicularly to the machine direction of

presses

50, 62, as illustrated in Fig. 1. With this arrangement, the segmental construction ofbase 10 provides flexing ofbase 10 as

belts

33, 45 are trained about the roll of long nip presses 50, 62 and about the upper surface of

pressure shoes

54, 66.

Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.