EP0188399A1 - Electromagnetic extended nip press - Google Patents
Electromagnetic extended nip press Download PDFInfo
- Publication number
- EP0188399A1 EP0188399A1 EP86630001A EP86630001A EP0188399A1 EP 0188399 A1 EP0188399 A1 EP 0188399A1 EP 86630001 A EP86630001 A EP 86630001A EP 86630001 A EP86630001 A EP 86630001A EP 0188399 A1 EP0188399 A1 EP 0188399A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- nip
- press
- members
- belt
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/0209—Wet presses with extended press nip
- D21F3/0218—Shoe presses
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/06—Means for regulating the pressure
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F7/00—Other details of machines for making continuous webs of paper
- D21F7/06—Indicating or regulating the thickness of the layer; Signal devices
Definitions
- This invention relates to the art of extended nip presses for papermaking machinery and the like utilizing electromagnets with large area core faces coextensive with the extended nip area on at least one side of the nip maintaining a concentrated magnetic field through an opposed conforming paramagnetic nip member for efficiently creating or augmenting the nip load on the paper web conveyed through the nip.
- this invention deals with extended nip presses having electromagnets on one or both sides of the nip with cores defining extended area shoes attracting opposed conforming magnetic nip members minimizing flux gaps between the opposed members to increase the attraction force for creating or augmenting the nip load on paper webs or the like conveyed through the nip.
- Extended nip presses for papermaking machines are known in the art, for example from the disclosures of the Busker et al United States Patent 3 738 225, issued July 24,1973, and the Justus United States Patent 3 783 097 issued January 1,1974.
- impervious belts convey the web through an extended wide nip created by hydraulically loaded shoes or pads.
- Roll presses with electromagnets in one roll attracting an opposing roll to create a nip load are also known, for example, from the disclosures of the McClenathan United States Patent 3 456 582, issued July 22,1969.
- an extended pressure nip for dewatering or calendering fibrous webs such as paper, is formed by magnetically attracting a wide shoe on one side of the web and a wide conforming paramagnetic member on the opposite side of the web which may take the form of a roll or a pressure shoe.
- the magnet core is coextensive with the wide nip area, forms or intimately supports the shoe and develops a concentrated magnetic field across the entire nip area. The field flux only traverses a minimum path to the opposed nip member.
- the web is conveyed through the nip by an impermeable belt and may be covered on one or both faces with an absorbent felt in dewatering press installations or may directly engage a hard finishing roll in calendering installations.
- the nip forming component on one side of the web is shiftable under the influence of the magnetic flux created by the energized electromagnet.
- either the shoe or the roll is shiftable and in installations having electromagnets on both sides of the nip either one or both of the magnets may be shiftable.
- a feature of the invention is the minimization of the gap through which the magnetic flux must pass to establish the nip load. This is accomplished by forming the pressure shoe with the electromagnet so that the - flux does not have to pass through a surrounding roll before reaching the paramagnetic nip forming member on the opposite side of the web.
- the shoe and opposed member have coextensive wide large areas increasing and concentrating the magnetic inductance to more effectively pull the two sides of the wide area nip together.
- Another feature of the invention is the provision of individual electromagnetic cores along the length of the nip to compensate for any irregularities in nip loads caused by deflection, uneven expansion and the like, of the components.
- a still further feature of the invention is to provide individual coils for the electromagnetic cores which are adapted to be individually energized to control loads along the length of the nip.
- a further object of the invention is to provide dewatering presses and calenders for papermaking machines with wide extended magnetized nips establishing nip loads by magnetic attraction.
- a further object of the invention is to provide a press roll assembly with an electromagnet energized shoe forming an extended nip with a cooperating magnetic roll and having a minimum gap between the electromagnet and the magnetic roll.
- Another object of this invention is to provide an extended nip press for papermaking machines where the wide area nip is formed by opposed electromagnets enhancing magnetic coupling of opposed rigid nip members.
- a still further object of the invention is to provide an electromagnet edtended nip press where the press loads are created by concentrated flux lines between opposed conforming wide area rigid nip members.
- the extended nip press assembly 10 of Fig. 1 has an electromagnet 11 on the bottom side of the wide or extended nip N, and a ferromagnetic top roll 12 on the opposite side of this nip.
- An impermeable belt 13 is trained in an open loop around rolls 14, one of which can be driven as shown at M and another can be biased as shown at B to tighten the belt.
- An external roll 15 guides the belt in its path having a top run through the nip.
- a porous felt 16 is trained around rolls 17 through the nip and receives the bottom face of a web W as it passes through the nip.
- the ferromagnetic roll 12 rotates about a fixed horizontal axis 18.
- the electromagnet 11 is slidably mounted in an open top fixed trough-like housing 19 and the top face of the electromagnet is covered with an arcuate non-magnetic thin sheet shoe 20, preferably formed from a sheet of stainless steel.
- This shoe 20 slidably supports the impermeable belt 13 and a shower pipe 21 ejects lubricating fluid between the shoe 20 and belt 13 at the entrance to the nip N.
- the electromagnet 11 is formed from a plurality of iron or magnetic steel core blocks 22 in side-by-side relation.
- the core blocks 22 are rectangular in shape with a flat bottom 23, flat parallel sides 24 and a transversely convex top 25.
- the blocks 25 have flat faces 26 adapted to slidably mate in side-by-side relation as illustrated.
- Each block 22 also has a pair of spaced side-by-side open top slots 27 extended between the opposite faces 26 thereof. These slots terminate above the bottom 23 of each block. An electromagnetic coil 28 is wound through the slots 27 terminating below the top 25 of each block and extending beyond the end blocks as shown.
- the slotted convex tops 25 of the blocks are covered with the thin non-magnetic shoe 20 which is curved to seat snugly on the tops of the blocks and which also has downturned lips 29 extending over and beyond the sides 24 of the blocks so that the impermeable belt 13 will be smoothly guided into and out of the nip N.
- the open top trough-like housing 19 is fixedly anchored and extends across the full length of the press assembly 10 inside the loop of the belt 13.
- the electromagnet 11 slides vertically in this housing and the sidewalls 24 of the magnet blocks 22 are slidably guided by the sidewalls of the trough and sealed to the trough by seals or packings such as 30.
- a sealed chamber 31 is provided between the bottoms 23 of the blocks 22 and the bottom of the trough and this chamber may receive hydraulic fluid under pressure from a pressure source 32 to force the electromagnet 11 and its cover 20 upwardly from the housing 19 to establish initial loading of the nip N.
- Other means for raising the electromagnet 11, such as screw rods, springs, or the like could be provided to hold the cover 20 against the impermeable belt 13 and to establish the initial loading of the nip.
- the coil 28 is energized from a generator G or the like power source through a resistor R controlling the amplitude of the current to create inductor excitation of the electromagnet establishing a controlled flux, drawing the slidable electromagnet and its cover shoe 20 toward the magnetic roll 12 and establishing the desired nip loading. Since the cover 20 is supported on the core blocks 22 and since these blocks are relatively slidable, irregularities in the nip contour due to sagging, heat expansion and the like will be neutralized and the blocks will maintain a uniform loading along the full length of the nip.
- the ferromagnetic top roll 12 instead of being mounted on the fixed axis 18 of the Fig. 1 embodiment, is mounted on an axis 18a supported from a hearings carried by swing arms such as 40, pivoted about a center 41 and actuated by hydraulic or pneumatic cylinders such as 42.
- the roll 12 is thus raised and lowered relative to the nip N.
- the electromagnet lla instead of being shiftable in a support such as 19, is fixedly mounted on a support 19a.
- the electromagnet lla has a single core block 43 with a central open top slot 44 receiving one leg of an electromagnet coil 45.
- the coil 45 thus envelops only one side of the block 43 and has one leg lying in the slot 44 while the other leg is wrapped around an outer side face of the block.
- the top of the coil is below the slotted convex top 46 of the block and the cover 20 is supported on this slotted top 46.
- Initial loading of the nip N in the press 10a is accomplished by actuating the cylinder such as 42 to pull the ends of the arms 40 forcing the bearings for the axis 18a downward into pressure nip relation with the cover 20.
- the desired nip pressure is then established by energizing the coil 45 creating the magnetic flux which pulls the ferromagnetic roll 12 to the core 43 and establishes the nip loading.
- the web is conveyed through the pressure nip on the impermeable belt 13 which slides over the shoe 20 and the felt 16 covers the bottom face of the web in the same manner as in the press embodiment 10.
- the nip loading can initially be created by forcing the electromagnet core against the shoe 20 on one side of the nip or by forcing the roll 12 toward the shoe on the opposite side of the nip and then energizing the electromagnets to create a dense concentrated magnetic field through the entire nip area pulling the magnet and roll together to create the desired augmented nip load.
- a double-felted press is provided with the web passing through the nip N between the bottom belt 16 and a top felt 50 which is wrapped around the bottom of the roll 12 and directed by guide rolls 51 to meet the web W as it enters the nip N and to leave this web as it exits from the nip.
- the roll 12 is circumferentially grooved as illustrated at 52 forming channels for the flow of water out of the nip N as shown in Fig. 10.
- the impermeable belt 13 may be longitudinally grooved as illustrated at 53 in Fig. 11 to form channels draining the water out of the nip.
- the press 10b may have the shiftable roll 12 and the fixed electromagnet lla of the press 10a in place of the fixed roll 12 and the shiftable magnet 11 of the press 10.
- the extended nip press 10c of Fig. 4 includes components the same as those illustrated and described hereinabove and the same reference numerals have been used to identify the components.
- the roll 12 is replaced with the shiftable electromagnet 11 and the trough support housing 19. This magnet slides in the housing 19 and acts through the shoe 20 to form the top face of the extended nip N.
- a top impermeable belt 60 trained around guide rolls 61 and a drive roll 62 in an open loop surrounding the housing 19 has a bottom run extending through the nip under the top shoe 20.
- a fixed lower electromagnet lla is surrounded by the looped bottom impermeable belt 13 riding over the bottom shoe 20.
- the web W is conveyed through the nip between the belts 13 and 60.
- Lubricant can be fed between the belts and shoes 20 at the entrance to the nip.
- the top electromagnet 11 can slide by gravity in the housing 19 to create an initial nip lqad.
- the initial load can be increased by hydraulic fluid, springs, or mechanical screws forcing the electromagnet 11 out of its housing 19 as described in the Fig. 1 embodiment.
- the fixed bottom electromagnet lla can be in the form of the single core end coil 45 with the external leg as shown in Fig. 7 or can be constructed as shown in Fig. 6.
- the bottom belt 13 is conveniently driven by a driver roll 63 with a superimposed nip loading roll 64, the belt passing through the nip between the rolls 63 and 64.
- a fibrous absorbent felt 65 is also provided between the top belt and the web W.
- the press 10d of Fig.5 illustrates a calender roll embodiment for surface finishing a dry web D.W. threaded through the nip N between a calender roll 70 rotatable about a fixed axis 71 and a shiftable electromagnet 11 carried in a housing 19 is described hereinabove.
- the electromagnet 11 is covered by the non-magnetic shoe 20 described hereinabove which in turn receives the impermeable belt 13 conveying the web D.W. through the nip N. Controlled energization of the electromagnet 11 creates the desired calender nip loading for treating the dry web D.W.
- an electromagnetic loading of the shoe 20 for an extended nip press or a cdander press as described hereinabove can be created by a modified electromagnet arrangement 80 composed of a plurality of electromagnet core blocks 81 each having its own individual exciting coil 82.
- the magnetic iron or steel core blocks have open top parallel slots 83 receiving the coil 82 with the ends of the coil projecting from the open ends of the slots.
- heads 83 are provided on the blocks extending beyond their front and back faces. This provides gaps or spaces 85 for the coils 82 without opening up wide gaps or spaces under the cover 20.
- each of the coils 82 can be individually energized from a power source 86 through controls 86a to vary the input to each coil as desired.
- the cores 81 spaced along the length of the nip can exert selective loads on increments of the shoe 20 to compensate for variations in nip pressures caused by sagging rolls, non-uniform expansions, etc. along the length of the nip.
- any gaps between the nip and the magnetic cores are minimized since the cores only act through very thin non-magnetic shoes 20 to establish the flux lines creating the attraction with opposed ferromagnetic rolls or cores. Further these flux lines only have very short paths between opposite sides of the nip and are concentrated over the complete nip area without passing through air gaps which are formed in all line presses at the entrance and exit sides of the nip.
- the extended nip area has a width controlled by the width of the shoe and all of this area has a magnetic field passing directly therethrough without going through an air gap, although a very small gap will be formed by the non-magnetic material going through the nip.
- the press 10e of Figure 12 provides a series of nips N successively receiving the web. Components similar to those shown in the presses 10,10a, 10b and 10c of Figs. 1-4 have been marked with the same reference numerals. As shown, the press 10e has three nips N, each defined by a roll 12 and a shiftable electromagnet 11 in a trough housing 19 with a thin non-magnetic shoe 20 covering the core blocks 22 and a pressured chamber 31 urging the magnet and shoe toward the opposing roll to establish an initial nip load. Each roll 12 has a separate press felt 90 wrapped therearound through the nip N provided by the roll and opposed shoe 20.
- Each felt 90 as illustrated on the third roll 12 is looped around rolls 91, one of which can be driven as shown at M.
- An external stretcher roll 92 keeps the loop taut and an external guide roll 93 keeps the felt on path around the roll 12, through the nip N and around the rolls 91.
- a single impermeable looped belt 94 has a top run through all three nips N, around a drive roll 95 beyond the last nip N, around rolls 96 back to the front nip N and over a guide roll 97 along a bottom run thereof.
- the magnets 11 can be energized to exert increasing nip loads in the successive nips N.
- the rolls 12 of the press 10e can be replaced with electromagnets 11 as in the press 10c of Fig. 4.
- a porous metal belt (not shown) can be used to replace the felts in the presses 10, 10a, 10b, 10c and 10e to thereby further reducing the non-magnetic gaps between the opposite rolls of the nips. Further the shoes 20 in the presses and calender stack arrangements can be eliminated to reduce the gaps, but because they are very thin, serve to keep the lubricating fluid away from the magnetic coils, and smooth out the nip surface, they are a desirable addition.
- a press roll 12a for the presses of this invention can be provided to minimize eddy current heating of the nip.
- the roll 12a has a cylindrical steel core 98 with end heads 99 carrying axles 99a to rotatably support the roll.
- the core receives a stack of thin laminates 100 therearound and squeezed together by the end heads 99.
- the stacked laminates 100 are washers about 0.01 to 0.051 cm thick and about 5.08 to 7.12 cm wide. They fit snugly on the core 98 and are composed of metal which does not develop eddy currents in the magnetic field generated by the electromagnets. Such eddy currents are created in conventional magnetic materials and heat the roll when it is driven through the magnetic field. When heat is not desired, laminated rolls such as 12a are used.
- Useful materials for the laminates are oriented silicon iron forming an oxide coating on the surfaces of the thin washers 100, noncrystallines or amorphous ferrites and the like.
- Fig. 14 illustrates the increases in attractive magnetic forces made possible by diminishing the gap through which the magnetic field must pass.
- the attractive force greatly increases as the gaps decrease from 1.91 cm down to 0.32 cm.
- Extrapolating the 0.32 cm curve to 14000 amp. turns shows that the electromagnets used in the extended press nip assemblies of this invention are capable of producing a force of 90 kilos per linear centimeter and that about twice this value can be achieved with two mutually attractive magnets as in the press assembly 10c of Fig. 4.
- the stacked heights of the non-magnetic shoes, belts, felts, and webs in the nips N of the presses of this invention only result in gaps of 0.127 cm to 0.914 cm between the magnetic cores and the ferromagnetic rolls or the opposed magnet core.
- the impermeable belt can ride on the lubricated core legs of the electromagnet eliminating the shoe 20.
- the shoe helps to keep the lubricant fluid from the coils. In such assemblies the shoe would only have a thickness of not more than about 0.32 centimeters each belt would have a thickness of 0.051 to 0.254 centimeters and, of course, the thickness of the webs would be negligible in the order of 0.005 to 0.025 centimeters.
- the impermeable belts are preferably composed of rubber or a plastic material such as polyurethane, but could be thin impermeable metal belts further reducing the non-magnetic gaps.
- the felts as explained above, can be replaced by thin porous flexible metal belts into and through which the expelled water can flow and still further reduce the gaps.
- the shoes 20 can be any non-magnetic material such as hard rubber, plastics material, stainless steel or the like.
- the machine direction width of the shoe can vary to suit conditions, but is wide enough to develop a large area magnetic field. A reasonable minimum width is about 10.16 cm with anaximum of about 45.72 cm.
- the cross machine direction width of the shoes can vary from narrow up to the full width of the machine.
- the full width shoe should be flexible with cross machine direction to conform to irregularities in the belts, felts , web and mating faces of the roll and magnet core. If desired the shoes can be spaced up to 15.24 cm apart.
- this invention provides extended nip presses for treating wet or dry fibrous webs wherein nip loading is created or augmented by electromagnets having cores acting only through minimum gaps creating the flux lines across the entire wide nip area which pull opposite sides of the nips toward each other to establish the desired nip loading throughout the entire width and length of the extended nip.
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Abstract
Description
- This invention relates to the art of extended nip presses for papermaking machinery and the like utilizing electromagnets with large area core faces coextensive with the extended nip area on at least one side of the nip maintaining a concentrated magnetic field through an opposed conforming paramagnetic nip member for efficiently creating or augmenting the nip load on the paper web conveyed through the nip. Specifically this invention deals with extended nip presses having electromagnets on one or both sides of the nip with cores defining extended area shoes attracting opposed conforming magnetic nip members minimizing flux gaps between the opposed members to increase the attraction force for creating or augmenting the nip load on paper webs or the like conveyed through the nip.
- Extended nip presses for papermaking machines are known in the art, for example from the disclosures of the Busker et al United States Patent 3 738 225, issued July 24,1973, and the Justus United States Patent 3 783 097 issued January 1,1974. In these disclosures impervious belts convey the web through an extended wide nip created by hydraulically loaded shoes or pads. Roll presses with electromagnets in one roll attracting an opposing roll to create a nip load are also known, for example, from the disclosures of the McClenathan United States Patent 3 456 582, issued July 22,1969. In such magnetic presses only a line nip is provided and wide gaps between the magnet and the opposed roll are formed due to the thickness of the roll housing the electromagnet and the converging and diverging air spaces at the entrance and exit to the line nip. These gaps substantially reduce the effectiveness of the electromagnet in creating the nip load.
- It would, therefore, be an improvement in this art to create nip pressures or loads in extended nip presses by electromagnets having large area massive cores immediately adjacent an opposed magnetic member to minimize gaps therebetween for maintaining a strong wide magnetic field creating a desired nip load.
- According to this invention an extended pressure nip for dewatering or calendering fibrous webs such as paper, is formed by magnetically attracting a wide shoe on one side of the web and a wide conforming paramagnetic member on the opposite side of the web which may take the form of a roll or a pressure shoe. The magnet core is coextensive with the wide nip area, forms or intimately supports the shoe and develops a concentrated magnetic field across the entire nip area. The field flux only traverses a minimum path to the opposed nip member. The web is conveyed through the nip by an impermeable belt and may be covered on one or both faces with an absorbent felt in dewatering press installations or may directly engage a hard finishing roll in calendering installations. The nip forming component on one side of the web is shiftable under the influence of the magnetic flux created by the energized electromagnet. Thus, in installations having an electromagnet shoe and a roll, either the shoe or the roll is shiftable and in installations having electromagnets on both sides of the nip either one or both of the magnets may be shiftable.
- A feature of the invention is the minimization of the gap through which the magnetic flux must pass to establish the nip load. This is accomplished by forming the pressure shoe with the electromagnet so that the - flux does not have to pass through a surrounding roll before reaching the paramagnetic nip forming member on the opposite side of the web. The shoe and opposed member have coextensive wide large areas increasing and concentrating the magnetic inductance to more effectively pull the two sides of the wide area nip together.
- Another feature of the invention is the provision of individual electromagnetic cores along the length of the nip to compensate for any irregularities in nip loads caused by deflection, uneven expansion and the like, of the components.
- A still further feature of the invention is to provide individual coils for the electromagnetic cores which are adapted to be individually energized to control loads along the length of the nip.
- It is then an objects of this invention to provide extended nip presses for papermaking machines and the like where the nip loads are created or augmented by wide area electromagnetic shoes.
- A further object of the invention is to provide dewatering presses and calenders for papermaking machines with wide extended magnetized nips establishing nip loads by magnetic attraction.
- A further object of the invention is to provide a press roll assembly with an electromagnet energized shoe forming an extended nip with a cooperating magnetic roll and having a minimum gap between the electromagnet and the magnetic roll.
- Another object of this invention is to provide an extended nip press for papermaking machines where the wide area nip is formed by opposed electromagnets enhancing magnetic coupling of opposed rigid nip members.
- A still further object of the invention is to provide an electromagnet edtended nip press where the press loads are created by concentrated flux lines between opposed conforming wide area rigid nip members.
- Other and further objects and features of this invention will be apparent to those skilled in this art from the following detailed description of the annexed sheets of drawings, which by way of preferred examples show several best mode embodiments of the invention.
- Fig. 1 is a schematic side view of an extended nip press of this invention having a shiftable electromagnet on one side of the nip and a fixed axis ferromagnetic roll on the opposite side of the nip.
- Fig. 2 is a schematic side view of an extended nip press of this invention having a fixed electromagnet on one side of the nip and a shiftable axis ferromagnetic roll on the opposite side of the nip.
- Fig. 3 is a schematic side view of an extended nip double felt press of this invention with a vented nip;
- Fig. 4 is a schematic side view of an extended nip press of this invention having electromagnets on both sides of the nip.
- Fig. 5 is a schematic side view of an extended nip calender type press of this invention.
- Fig. 6 is an isometric view of a shiftable electromagnet shoe assembly for presses of this invention.
- Fig. 7 is an isometric view of another form of electromagnet core for presses of this invention.
- Fig. 8 is a schematic longitudinal view of an electromagnet shoe for the presses of this invention having a plurality of cores individually energized by coils and with expanded core heads to accommodate the individual coil wrappings.
- Fig. 9 is an end view along the line IX-IX of Fig. 8.
- Fig. 10 is a cross-sectional view along the line X-X_of Fig. 3.
- Fig. 11 is a cross-sectional view along the line XI-XI of Fig. 3.
- Fig. 12 is a schematic side view of multiple extended nip press of this invention.
- Fig. 13 is a schematic longitudinal cross section view of a laminated press roll useful in the presses of this invention to minimize heating.
- Fig. 14 is a graph showing nip loading as a function of electromagnet excitation and illustrating the increases in magnetic coupling with decreases in gaps between the electromagnet core and the opposing magnetic member.
- The extended
nip press assembly 10 of Fig. 1 has anelectromagnet 11 on the bottom side of the wide or extended nip N, and aferromagnetic top roll 12 on the opposite side of this nip. Animpermeable belt 13 is trained in an open loop aroundrolls 14, one of which can be driven as shown at M and another can be biased as shown at B to tighten the belt. Anexternal roll 15 guides the belt in its path having a top run through the nip. Aporous felt 16 is trained aroundrolls 17 through the nip and receives the bottom face of a web W as it passes through the nip. Theferromagnetic roll 12 rotates about a fixedhorizontal axis 18. Theelectromagnet 11 is slidably mounted in an open top fixed trough-like housing 19 and the top face of the electromagnet is covered with an arcuate non-magneticthin sheet shoe 20, preferably formed from a sheet of stainless steel. Thisshoe 20 slidably supports theimpermeable belt 13 and ashower pipe 21 ejects lubricating fluid between theshoe 20 and belt 13 at the entrance to the nip N. - As shown in Fig. 6, the
electromagnet 11 is formed from a plurality of iron or magneticsteel core blocks 22 in side-by-side relation. Thecore blocks 22 are rectangular in shape with aflat bottom 23, flatparallel sides 24 and a transverselyconvex top 25. Theblocks 25 haveflat faces 26 adapted to slidably mate in side-by-side relation as illustrated. - Each
block 22 also has a pair of spaced side-by-side open top slots 27 extended between theopposite faces 26 thereof. These slots terminate above thebottom 23 of each block. Anelectromagnetic coil 28 is wound through the slots 27 terminating below thetop 25 of each block and extending beyond the end blocks as shown. - The slotted
convex tops 25 of the blocks are covered with the thinnon-magnetic shoe 20 which is curved to seat snugly on the tops of the blocks and which also has downturnedlips 29 extending over and beyond thesides 24 of the blocks so that theimpermeable belt 13 will be smoothly guided into and out of the nip N. - The open top trough-
like housing 19 is fixedly anchored and extends across the full length of thepress assembly 10 inside the loop of thebelt 13. Theelectromagnet 11 slides vertically in this housing and thesidewalls 24 of themagnet blocks 22 are slidably guided by the sidewalls of the trough and sealed to the trough by seals or packings such as 30. - A sealed
chamber 31 is provided between thebottoms 23 of theblocks 22 and the bottom of the trough and this chamber may receive hydraulic fluid under pressure from apressure source 32 to force theelectromagnet 11 and itscover 20 upwardly from thehousing 19 to establish initial loading of the nip N. Other means for raising theelectromagnet 11, such as screw rods, springs, or the like could be provided to hold thecover 20 against theimpermeable belt 13 and to establish the initial loading of the nip. - The
coil 28 is energized from a generator G or the like power source through a resistor R controlling the amplitude of the current to create inductor excitation of the electromagnet establishing a controlled flux, drawing the slidable electromagnet and itscover shoe 20 toward themagnetic roll 12 and establishing the desired nip loading. Since thecover 20 is supported on thecore blocks 22 and since these blocks are relatively slidable, irregularities in the nip contour due to sagging, heat expansion and the like will be neutralized and the blocks will maintain a uniform loading along the full length of the nip. - In the extended
nip press 10a of Fig. 2, parts corresponding with the parts described in thepress 10 have been marked with the same reference numerals. In the press l0a , however, theferromagnetic top roll 12, instead of being mounted on thefixed axis 18 of the Fig. 1 embodiment, is mounted on an axis 18a supported from a hearings carried by swing arms such as 40, pivoted about a center 41 and actuated by hydraulic or pneumatic cylinders such as 42. Theroll 12 is thus raised and lowered relative to the nip N. - The electromagnet lla, instead of being shiftable in a support such as 19, is fixedly mounted on a
support 19a. - As shown in Fig. 7, the electromagnet lla has a
single core block 43 with a centralopen top slot 44 receiving one leg of anelectromagnet coil 45. Thecoil 45 thus envelops only one side of theblock 43 and has one leg lying in theslot 44 while the other leg is wrapped around an outer side face of the block. The top of the coil is below theslotted convex top 46 of the block and thecover 20 is supported on thisslotted top 46. - Initial loading of the nip N in the
press 10a is accomplished by actuating the cylinder such as 42 to pull the ends of thearms 40 forcing the bearings for the axis 18a downward into pressure nip relation with thecover 20. The desired nip pressure is then established by energizing thecoil 45 creating the magnetic flux which pulls theferromagnetic roll 12 to thecore 43 and establishes the nip loading. The web is conveyed through the pressure nip on theimpermeable belt 13 which slides over theshoe 20 and the felt 16 covers the bottom face of the web in the same manner as in thepress embodiment 10. - From these descriptions of the
press embodiments shoe 20 on one side of the nip or by forcing theroll 12 toward the shoe on the opposite side of the nip and then energizing the electromagnets to create a dense concentrated magnetic field through the entire nip area pulling the magnet and roll together to create the desired augmented nip load. - In the
press 10b of Fig.3 parts corresponding to parts illustrated and described in theembodiments bottom belt 16 and atop felt 50 which is wrapped around the bottom of theroll 12 and directed by guide rolls 51 to meet the web W as it enters the nip N and to leave this web as it exits from the nip. - To facilitate drainage of water squeezed from the web W out of the extended nip N, the
roll 12 is circumferentially grooved as illustrated at 52 forming channels for the flow of water out of the nip N as shown in Fig. 10. - The
impermeable belt 13 may be longitudinally grooved as illustrated at 53 in Fig. 11 to form channels draining the water out of the nip. - It will be understood that either the
roll 12 or thebelt 13, or both, may be grooved. - It will also be understood that the
press 10b may have theshiftable roll 12 and the fixed electromagnet lla of thepress 10a in place of the fixedroll 12 and theshiftable magnet 11 of thepress 10. - The
extended nip press 10c of Fig. 4 includes components the same as those illustrated and described hereinabove and the same reference numerals have been used to identify the components. In thepress 10c, theroll 12 is replaced with theshiftable electromagnet 11 and thetrough support housing 19. This magnet slides in thehousing 19 and acts through theshoe 20 to form the top face of the extended nip N. A topimpermeable belt 60 trained around guide rolls 61 and a drive roll 62 in an open loop surrounding thehousing 19 has a bottom run extending through the nip under thetop shoe 20. - A fixed lower electromagnet lla is surrounded by the looped bottom
impermeable belt 13 riding over thebottom shoe 20. The web W is conveyed through the nip between thebelts shoes 20 at the entrance to the nip. - The
top electromagnet 11 can slide by gravity in thehousing 19 to create an initial nip lqad. In addition, the initial load can be increased by hydraulic fluid, springs, or mechanical screws forcing theelectromagnet 11 out of itshousing 19 as described in the Fig. 1 embodiment. - The fixed bottom electromagnet lla can be in the form of the single
core end coil 45 with the external leg as shown in Fig. 7 or can be constructed as shown in Fig. 6. - The
bottom belt 13 is conveniently driven by adriver roll 63 with a superimposednip loading roll 64, the belt passing through the nip between therolls - A fibrous absorbent felt 65 is also provided between the top belt and the web W.
- When the coils of the
electromagnets 11 and lla are energized the cores of these magnets are drawn or pulled together pushing the shoes20 on opposite sides of the web toward each other and loading the nip to establish the desired pressure. Since both sides of the nip have electromagnets, the attraction force will be substantially greater, probably double, the force obtained in theembodiments - The
press 10d of Fig.5 illustrates a calender roll embodiment for surface finishing a dry web D.W. threaded through the nip N between acalender roll 70 rotatable about a fixed axis 71 and ashiftable electromagnet 11 carried in ahousing 19 is described hereinabove. Theelectromagnet 11 is covered by thenon-magnetic shoe 20 described hereinabove which in turn receives theimpermeable belt 13 conveying the web D.W. through the nip N. Controlled energization of theelectromagnet 11 creates the desired calender nip loading for treating the dry web D.W. - As shown in Figs. 8 and 9 an electromagnetic loading of the
shoe 20 for an extended nip press or a cdander press as described hereinabove can be created by a modifiedelectromagnet arrangement 80 composed of a plurality of electromagnet core blocks 81 each having its own individualexciting coil 82. As shown, the magnetic iron or steel core blocks have open topparallel slots 83 receiving thecoil 82 with the ends of the coil projecting from the open ends of the slots. To provide for coil clearance between the adjacent core blocks 81, heads 83 are provided on the blocks extending beyond their front and back faces. This provides gaps orspaces 85 for thecoils 82 without opening up wide gaps or spaces under thecover 20. - As diagrammatically illustrated in Figure 8, the ends of each of the
coils 82 can be individually energized from apower source 86 throughcontrols 86a to vary the input to each coil as desired. In this manner, thecores 81 spaced along the length of the nip can exert selective loads on increments of theshoe 20 to compensate for variations in nip pressures caused by sagging rolls, non-uniform expansions, etc. along the length of the nip. - It will be noted any gaps between the nip and the magnetic cores are minimized since the cores only act through very thin
non-magnetic shoes 20 to establish the flux lines creating the attraction with opposed ferromagnetic rolls or cores. Further these flux lines only have very short paths between opposite sides of the nip and are concentrated over the complete nip area without passing through air gaps which are formed in all line presses at the entrance and exit sides of the nip. In the extended nip presses of this invention the extended nip area has a width controlled by the width of the shoe and all of this area has a magnetic field passing directly therethrough without going through an air gap, although a very small gap will be formed by the non-magnetic material going through the nip. - The
press 10e of Figure 12 provides a series of nips N successively receiving the web. Components similar to those shown in thepresses press 10e has three nips N, each defined by aroll 12 and ashiftable electromagnet 11 in atrough housing 19 with a thinnon-magnetic shoe 20 covering the core blocks 22 and a pressuredchamber 31 urging the magnet and shoe toward the opposing roll to establish an initial nip load. Eachroll 12 has a separate press felt 90 wrapped therearound through the nip N provided by the roll andopposed shoe 20. Each felt 90 as illustrated on thethird roll 12 is looped around rolls 91, one of which can be driven as shown at M. Anexternal stretcher roll 92 keeps the loop taut and anexternal guide roll 93 keeps the felt on path around theroll 12, through the nip N and around therolls 91. A single impermeable looped belt 94 has a top run through all three nips N, around adrive roll 95 beyond the last nip N, around rolls 96 back to the front nip N and over aguide roll 97 along a bottom run thereof. - The
magnets 11 can be energized to exert increasing nip loads in the successive nips N. - The
rolls 12 of thepress 10e can be replaced withelectromagnets 11 as in thepress 10c of Fig. 4. - A porous metal belt (not shown) can be used to replace the felts in the
presses shoes 20 in the presses and calender stack arrangements can be eliminated to reduce the gaps, but because they are very thin, serve to keep the lubricating fluid away from the magnetic coils, and smooth out the nip surface, they are a desirable addition. - As shown in Fig. 13, a press roll 12a for the presses of this invention can be provided to minimize eddy current heating of the nip. The roll 12a has a
cylindrical steel core 98 with end heads 99 carryingaxles 99a to rotatably support the roll. The core receives a stack of thin laminates 100 therearound and squeezed together by the end heads 99. The stacked laminates 100 are washers about 0.01 to 0.051 cm thick and about 5.08 to 7.12 cm wide. They fit snugly on thecore 98 and are composed of metal which does not develop eddy currents in the magnetic field generated by the electromagnets. Such eddy currents are created in conventional magnetic materials and heat the roll when it is driven through the magnetic field. When heat is not desired, laminated rolls such as 12a are used. - Useful materials for the laminates are oriented silicon iron forming an oxide coating on the surfaces of the thin washers 100, noncrystallines or amorphous ferrites and the like.
- Fig. 14 illustrates the increases in attractive magnetic forces made possible by diminishing the gap through which the magnetic field must pass. Thus, as illustrated in the
graph 101, plotting inductor excitation in terms of amperage turns from 0 to 14000 asabscissa 102 and static attractive forces in terms of kilos per linear centimeter asordinates 103, the attractive force greatly increases as the gaps decrease from 1.91 cm down to 0.32 cm. Extrapolating the 0.32 cm curve to 14000 amp. turns shows that the electromagnets used in the extended press nip assemblies of this invention are capable of producing a force of 90 kilos per linear centimeter and that about twice this value can be achieved with two mutually attractive magnets as in thepress assembly 10c of Fig. 4. - The stacked heights of the non-magnetic shoes, belts, felts, and webs in the nips N of the presses of this invention, only result in gaps of 0.127 cm to 0.914 cm between the magnetic cores and the ferromagnetic rolls or the opposed magnet core. As explained above, the impermeable belt can ride on the lubricated core legs of the electromagnet eliminating the
shoe 20. The shoe, however, helps to keep the lubricant fluid from the coils. In such assemblies the shoe would only have a thickness of not more than about 0.32 centimeters each belt would have a thickness of 0.051 to 0.254 centimeters and, of course, the thickness of the webs would be negligible in the order of 0.005 to 0.025 centimeters. The impermeable belts are preferably composed of rubber or a plastic material such as polyurethane, but could be thin impermeable metal belts further reducing the non-magnetic gaps. The felts, as explained above, can be replaced by thin porous flexible metal belts into and through which the expelled water can flow and still further reduce the gaps. Theshoes 20 can be any non-magnetic material such as hard rubber, plastics material, stainless steel or the like. The machine direction width of the shoe can vary to suit conditions, but is wide enough to develop a large area magnetic field. A reasonable minimum width is about 10.16 cm with anaximum of about 45.72 cm. The cross machine direction width of the shoes can vary from narrow up to the full width of the machine. The full width shoe should be flexible with cross machine direction to conform to irregularities in the belts, felts , web and mating faces of the roll and magnet core. If desired the shoes can be spaced up to 15.24 cm apart. - As explained above, as the metal rolls rotate through the magnetic field, heat is generated which can be helpful in wet presses. If heat is not wanted the rolls can be laminated as shown in Fig. 13 and as described above.
- From the above description it should be understood that this invention provides extended nip presses for treating wet or dry fibrous webs wherein nip loading is created or augmented by electromagnets having cores acting only through minimum gaps creating the flux lines across the entire wide nip area which pull opposite sides of the nips toward each other to establish the desired nip loading throughout the entire width and length of the extended nip.
Claims (20)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US68980085A | 1985-01-08 | 1985-01-08 | |
US689800 | 2003-10-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0188399A1 true EP0188399A1 (en) | 1986-07-23 |
EP0188399B1 EP0188399B1 (en) | 1989-10-25 |
Family
ID=24769937
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86630001A Expired EP0188399B1 (en) | 1985-01-08 | 1986-01-06 | Electromagnetic extended nip press |
Country Status (13)
Country | Link |
---|---|
EP (1) | EP0188399B1 (en) |
JP (1) | JPS61174494A (en) |
KR (1) | KR890000820B1 (en) |
CN (1) | CN1006916B (en) |
BR (1) | BR8600047A (en) |
CA (1) | CA1249470A (en) |
DE (1) | DE3666598D1 (en) |
ES (1) | ES8705548A1 (en) |
FI (1) | FI85521C (en) |
IN (1) | IN165321B (en) |
MX (1) | MX160381A (en) |
PH (1) | PH24538A (en) |
PL (1) | PL148514B1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1988008051A1 (en) * | 1987-04-14 | 1988-10-20 | J.M. Voith Gmbh | Machine for manufacture of webs of fibrous materials |
US5836242A (en) * | 1994-06-15 | 1998-11-17 | Albany Nordiskafilt Ab | Calendering system including a belt having an adaptable web-contacting surface |
US6007921A (en) * | 1992-10-09 | 1999-12-28 | Champion International Corporation | Continuous finishing belt capable of finishing surface of a web of paper |
WO2000047815A1 (en) * | 1999-02-09 | 2000-08-17 | Sgm S.P.A. | Calender with magnetic device for adjusting the contact pressure between the rolls |
US6203307B1 (en) * | 1997-08-28 | 2001-03-20 | Champion International Corporation | System for finishing surface of a web of paper having an improved continuous finishing belt |
DE10157686A1 (en) * | 2001-11-24 | 2003-06-12 | Voith Paper Patent Gmbh | Calender and method for smoothing a paper or board web |
CN112519072A (en) * | 2020-11-23 | 2021-03-19 | 德清新源恒塑料科技有限公司 | Polytetrafluoroethylene film calender |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19613878C1 (en) * | 1996-04-06 | 1997-06-12 | Voith Sulzer Finishing Gmbh | Calender for paper, having two treatment points |
CN105789499B (en) * | 2016-04-26 | 2019-08-13 | 福建南平南孚电池有限公司 | A kind of alkaline battery sealing ring |
CN113463425A (en) * | 2021-06-03 | 2021-10-01 | 江辉辉 | Paper machine protection device capable of adjusting paper squeezing degree |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3067718A (en) * | 1958-11-05 | 1962-12-11 | Johannes Zimmer Maschf | Apparatus for treating sheet materials |
US3456582A (en) * | 1966-09-29 | 1969-07-22 | Beloit Corp | Crownless electromagnetic press roll loading |
US4482430A (en) * | 1982-04-01 | 1984-11-13 | Oy. Tampella Ab | Extended nip press lubricating system for a paper machine |
-
1985
- 1985-11-18 CA CA000495567A patent/CA1249470A/en not_active Expired
- 1985-11-27 PH PH33104A patent/PH24538A/en unknown
- 1985-12-09 FI FI854845A patent/FI85521C/en not_active IP Right Cessation
- 1985-12-14 CN CN85108792A patent/CN1006916B/en not_active Expired
- 1985-12-28 JP JP60299815A patent/JPS61174494A/en active Granted
- 1985-12-31 KR KR1019850010108A patent/KR890000820B1/en not_active IP Right Cessation
-
1986
- 1986-01-06 IN IN15/CAL/86A patent/IN165321B/en unknown
- 1986-01-06 DE DE8686630001T patent/DE3666598D1/en not_active Expired
- 1986-01-06 EP EP86630001A patent/EP0188399B1/en not_active Expired
- 1986-01-07 ES ES550697A patent/ES8705548A1/en not_active Expired
- 1986-01-08 PL PL1986257394A patent/PL148514B1/en unknown
- 1986-01-08 BR BR8600047A patent/BR8600047A/en not_active IP Right Cessation
- 1986-01-14 MX MX1216A patent/MX160381A/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3067718A (en) * | 1958-11-05 | 1962-12-11 | Johannes Zimmer Maschf | Apparatus for treating sheet materials |
US3456582A (en) * | 1966-09-29 | 1969-07-22 | Beloit Corp | Crownless electromagnetic press roll loading |
US4482430A (en) * | 1982-04-01 | 1984-11-13 | Oy. Tampella Ab | Extended nip press lubricating system for a paper machine |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1988008051A1 (en) * | 1987-04-14 | 1988-10-20 | J.M. Voith Gmbh | Machine for manufacture of webs of fibrous materials |
US6007921A (en) * | 1992-10-09 | 1999-12-28 | Champion International Corporation | Continuous finishing belt capable of finishing surface of a web of paper |
US5836242A (en) * | 1994-06-15 | 1998-11-17 | Albany Nordiskafilt Ab | Calendering system including a belt having an adaptable web-contacting surface |
US6203307B1 (en) * | 1997-08-28 | 2001-03-20 | Champion International Corporation | System for finishing surface of a web of paper having an improved continuous finishing belt |
WO2000047815A1 (en) * | 1999-02-09 | 2000-08-17 | Sgm S.P.A. | Calender with magnetic device for adjusting the contact pressure between the rolls |
US6349637B1 (en) | 1999-02-09 | 2002-02-26 | Sgm, S.P.A. | Calender with magnetic device for adjusting the contact pressure between the rolls |
DE10157686A1 (en) * | 2001-11-24 | 2003-06-12 | Voith Paper Patent Gmbh | Calender and method for smoothing a paper or board web |
DE10157686B4 (en) * | 2001-11-24 | 2005-11-17 | Voith Paper Patent Gmbh | Calender and method for smoothing a paper or board web |
CN112519072A (en) * | 2020-11-23 | 2021-03-19 | 德清新源恒塑料科技有限公司 | Polytetrafluoroethylene film calender |
Also Published As
Publication number | Publication date |
---|---|
EP0188399B1 (en) | 1989-10-25 |
FI854845A0 (en) | 1985-12-09 |
JPS61174494A (en) | 1986-08-06 |
CN85108792A (en) | 1986-11-05 |
DE3666598D1 (en) | 1989-11-30 |
CN1006916B (en) | 1990-02-21 |
CA1249470A (en) | 1989-01-31 |
PL257394A1 (en) | 1987-04-21 |
ES8705548A1 (en) | 1987-05-01 |
KR860005935A (en) | 1986-08-16 |
PL148514B1 (en) | 1989-10-31 |
KR890000820B1 (en) | 1989-04-08 |
FI85521B (en) | 1992-01-15 |
PH24538A (en) | 1990-08-03 |
ES550697A0 (en) | 1987-05-01 |
BR8600047A (en) | 1986-09-23 |
FI854845A (en) | 1986-07-09 |
JPH0219237B2 (en) | 1990-05-01 |
IN165321B (en) | 1989-09-23 |
FI85521C (en) | 1992-04-27 |
MX160381A (en) | 1990-02-14 |
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