A shoe for a paper machine press, belt roll comprising the shoe, and paper making machine comprising the belt roll

Description

The proposed technology relates generally to a shoe for a belted roll for use with a paper machine.BackgroundIn a paper making machine, an extended nip press is generally used for pressing water out of a newly formed wet fibrous web. An extended nip may also be used for other purposes, e.g. calendering. Although extended nip presses were first introduced for heavy grades such as paperboard, they have also come to be used for lighter grades such as printing paper and even for tissue paper. When making tissue paper, the extended nip press is often formed by an extended nip roll and a Yankee drying cylinder that acts as a counter roll for the extended nip roll.An extended nip press, especially in a machine for making tissue paper, is typically formed by an extended nip roll that comprises a working surface that is pressed against the counter roll. The purpose of the extended nip press is to dewater a fibrous web during production of paper.The working surface can form part of a shoe and the shoe may be pressed towards the counter roll to apply a nip load. The shoe may be surrounded by a rotating belt, or jacket or blanket that slides over the working surface. A lubricant may be applied between the shoe and the belt.A problem with known shoe presses is that in a case of broken uniformity of the lubricating oil film, the belt may contact the shoe. This may lead to mechanical wear on the belt due to the friction between the working surface of the shoe and the belt. In addition, increased friction is undesirable as the power reguired to drive the web at a desired speed through the paper machine increases. This may further lead to undesirable heating of the belt and may lead to a degradation of material of the belt. These problems may result in a reduced life of the shoe and / or the belt.It is an object of the proposed technology to provide a shoe with a working surface that reduces the wear of the belt and improves belt durability. It is a further object to provide a shoe that improves lubrication of the working surface of the shoe and the belt surface facing the shoe.SummaryIn a first aspect of the proposed technology, a press shoe for a paper making machine is provided, wherein the shoe is arranged to be mounted in, or installed into, a belt, or sleeve, or jacket, roll, wherein the shoe comprises:-a working surface, or sole, or contact surface, arranged to face and contact a belt, or sleeve, or jacket, and cooperate with a counter roll, to form a press nip, wherein the working surface of the shoe is made from a polymer material, and the working surface has a surface roughness Ra that is less than 20 pm, preferably less than 6 pm, and more preferably less than 1 pm.The shoe may be mounted in, or installed into, a belt, or sleeve, or jacket, roll. Worded differently, the shoe may form part of a belt, or sleeve, or jacket, roll. The extended belt roll may in turn be arranged to cooperate with, and apply a force to, a web of material and a counter roll, wherein the counter roll and the extended nip roll are arranged to together form a nip press. Worded differently, the counter roll and the extended nip roll may form a nip press. Such a press may comprise:a shoe, a belt, or sleeve, or jacket, and a lubricating fluid layer arranged between the belt and the shoe.It is understood that the shoe is maintained in a stationary, or fixed position, relative to the belt that contacts and slides relative to the shoe when the shoe presses the belt towards, or in a direction facing, the counter roll.It is specified above that the shoe has a working surface and that the working surface has a specified surface roughness. The technical effect is that the oil layer is maintained on the shoe, or between the shoe and the belt. This in turn reduces friction between the belt and the shoe and wear is thereby reduced. In addition, the specified surface roughness reduces wear of the belt and the working surface during operation of the belt roll and during a full or partial loss of the lubrication layer. In extension reducing the friction will also reduce the electric power usage of a paper mill operating the belt roll.It is specified above that the belt roll may be arranged to cooperate with, and apply a force to, a counter roll. The belt of the belt roll and the counter roll rotate around a respective rotation axis. The belt of the belt roll rotates in a first direction around the rotation axis of the belt roll. The counter roll rotates in a second direction, opposite the first direction, around the rotation axis of the counter roll. Transverse to the respective rotation axis is a machine direction. The machine direction may be perpendicular to the rotation axis of the belt and / or the counter roll. It is understood that the belt roll and the counter roll together form a nip. Wording the machine direction differently, the machine direction may be parallel, and coincides with, the web feed direction into the nip. At the nip, a tangent of the counter roll and a tangent of the belt roll may be parallel.It is understood that surface roughness is a component of surface finish, or surface texture. Surface roughness may be guantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth. It is further understood that tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. In tribology, rough surfaces usually wear more guickly and have higher friction coefficients than smooth surfaces. It is further understood that the surface roughness Ra is measured using ISO 4287:1997 standard.It is understood that the Shore A hardness and Shore D hardness is measured using an ASTM D2240 Shore durometer and following DIN ISO 7619-1 standard, superseded by ISO 48-4:2018.It is further understood that the Shore A hardness and Shore D hardness scales partially overlap and that a Shore A value may be converted to a Shore D value. A Shore A hardness values may thus correspond to a Shore D value. It is further understood that for Shore A hardness values above 95, it is preferable to switch to Shore D hardness values.For example, it is understood that a Shore A value of 50 corresponds to a Shore D value of 12, and that a Shore A value of 90 corresponds to a Shore D value of 39, and that a Shore A value of 95 corresponds to a Shore D value of 46.Accordingly, when a hardness value is specified herein the value may be converted from a Shore A hardness to a Shore D hardness.It is understood that the surface roughness may be added, or imparted, to the working surface by buffing.It is specified above that the working surface of the shoe is made from a polymer material and that the working surface has a surface roughness Ra that is less than 20 μm, preferably less than 6 μm, and more preferably less than 1 pm. The surface roughness may be formed by polishing the working surface. In one embodiment the surface roughness Ra of the working surface is about 3.2 μm. In a further embodiment the surface roughness may be in the range of 1-3 μm.In a further embodiment the surface roughness may be less than 15 μm, less than 10 μm or less than 6 μm.In a further embodiment the working surface may be manufactured by casting or molding. This may eliminate the need for the manufacturing step of polishing the working surface and result in a surface roughness in the range of 0.1 pm to 0.2 μm.The inventors have found that the working surface of the shoe having the above specified surface roughness provides for improved lubrication layer and reduced risk of wear during use, and if lubrication layer uniformity is lost.Worded differently, providing the working surface with the above surface roughness provides for sufficient lubricant to be retained on the belt, and between the shoe and the belt, and reduces friction. Thereby heat generated due to friction between the belt and the working surface. In extension, this prolongs life of the belt and reduces the risk of belt damage.The working surface, or shoe, may have a Shore hardness the range of 50 shore A to 65 shore D. Worded differently, the working surface, or shoe, may have a Shore hardness the range of 12 Shore D to 65 Shore D.Preferably, the working surface, or shoe, may have a Shore hardness in the range of 80 Shore A to 60 Shore D.Worded differently, preferably the working surface, or shoe, may preferably have a Shore hardness in the range of 29 Shore □ to 60 Shore D.More preferably, the working surface, or shoe, may have a Shore hardness is in the range of 85 Shore A to 56 Shore D. Worded differently, more preferably the working surface, or shoe, may preferably have a Shore hardness in the range of 33 ShoreD to 56 Shore D.In a further example, the working surface, or shoe, may have a Shore hardness in the range of 90 Shore A to 60 Shore D. Worded differently, preferably the working surface, or shoe, may preferably have a Shore hardness in the range of 39 ShoreD to 60 Shore D. In a further example, the working surface, or shoe, may have a Shore hardness is in the range of 92 Shore A to 56 Shore D. Thereby, the first material is rendered soft and flexible enough to provide a desired pressure profile in the nip and provide an efficient and when the shoe is used in an extended nip, provide improved dewatering of the fibrous web as well as preventing excessive wear on components of the press, such as the working surface. In addition, the inventors have found that the above ranges for surface roughness of the working surface together with the Shore hardness of the working surface specified above may provide for an improved lubrication layer and a reduced risk of wear during use, and if lubrication layer uniformity is lost while providing optimal nip pressure and pressure distribution in the nip along the machine direction.The shoe may have a forward edge and a rearward edge. It is understood that the forward edge may be arranged upstream the rearward edge in the machine direction. Worded differently, the forward edge may be arranged about the entrance of the nip, and the rearward edge may be arranged about the exit of the nip. The web of material that passes through the nip in the machine direction will thus first pass the forward edge, and subseguently pass the rearward edge. The forward edge may be transverse, or perpendicular, to the machine direction. The forward edge may be parallel to the rotation axis of the belt roll, or counter roll. The rearward edge may be transverse, or perpendicular, to the machine direction. The rearward edge may be parallel to the rotation axis of the belt roll, or counter roll. The shoe may have a longitudinal extension in a direction transverse to the machine direction, or parallel to the rotation axis of the belt roll or the counter roll. The longitudinal extension, or the length of the shoe, may be in the range of 1200 mm —8000 mm, preferably in the range of 2500 mm —8000 mm.The shoe may have a width in the machine direction, between the forward edge and the rearward edge. The width may be in the range of 5mm to 120 mm, preferably 40 mm to 120 mm. In one example, the belt roll forms part of an extended nip and the width may be 250-330 mm.The shoe may have height, or a thickness, in a transverse direction to the width of the shoe. Worded differently, the height may be transverse to the machine direction, and transverse to the rotation axis of the nip roll, or counter roll.The shoe may comprise a base body and a sole. Worded differently, the shoe may be formed by a base body and a sole. The sole may have the forward edge and the rearward edge disclosed above in relation to the shoe. It is understood that the sole may have, or comprise, the working surface. The complete shoe may be made from a polymer material. The shoe may be made from a synthetic polymer or synthetic rubber material, such as polyurethane, or urethane. In one embodiment the polymer material is a composite polymer material the shoe is made from a composite polymer material comprising a polymer matrix material and reinforcing fibers mixed, or dispersed into, the polymer matrix material.It is understood that the base body and / or the sole may be made from the polymer material. This means that both the base body and the sole may be made from the same material, and from a synthetic polymer, or synthetic rubber, material, such as polyurethane.Alternatively, only the sole with the working surface may be made from the polymer material and the base body may be made from a different material.By providing the base body separately from the sole, separate manufacturing processes, or steps, or materials may be applied for the base body and the sole, each of these bodies may be manufactured in separate processes and be mounted, or assembled, or joined, together.This provides a significant advantage over known prior art solutions, since manufacture of the base body and of the sole in separate processes may be easier and more efficient than joining them together in the known complex manufacturing processes. In addition, the base body and the sole may be separably serviceable, or replaceable.The sole may be arranged to the base body by an adhesive. Alternatively, the sole may be moulded onto the base body. For example, a mould may first be partially filled with a first liguid material and after setting, or curing, a second liguid material may be poured into, and fill remaining volume of the mould. After the second liguid material has set, or cured, the shoe may be removed from the mould and the surface roughness may be added, or mechanically, be machined or otherwise applied to form the working surface of the shoe as will be described below.The sole may have a thickness parallel to the height of the shoe. The thickness may be in the range of 5-50 mm, preferably in the range of 5-30 mm. When the sole is nonplanar, such as convex or concave, the thickness of the sole may be varied along the width of the shoe, in the machine direction.It is specified above that the working surface, or shoe, or contact surface is in a polymer material, and has a surface roughness Ra that is less than 20 μm, preferably less than 6 μm, and more preferably less than 1 μm. The working surface may form part of the sole. Worded differently, the sole may form the working surface of the shoe. The sole may comprise a first working surface part, or portion, and a second working surface part, or portion, wherein the first working surface part, or portion, has a surface roughness Ra that is less than 20 μm, preferably less than 6 μm, and more preferably less than 1 μm, and wherein the second working surface part, or portion, has a different surface roughness, preferably a surface roughness above the surface roughness of the first working surface part , or portion. In a further embodiment the surface roughness of the first working surface may be in the range of 1-3 μm.The first working surface portion may be positioned between the forward edge and a rearward edge of the shoe. The second working surface portion may be positioned at the forward edge and / or the rearward edge of the sole. The first working surface may be positioned about the middle of the shoe. Worded differently, the first workings surface may be located at a position halfway between the forward edge and the rearward edge.Alternatively, the first working surface portion may be positioned at the forward edge of the sole, and the second working surface portion may be positioned at the rearward edge of the sole. In a further alternatively, the second working surface portion may be positioned at the forward edge of the sole, and the first working surface portion may be positioned at the rearward edge of the sole. The first working surface portion may extend from an edge of the sole to the middle of the workings surface, between the forward edge and the rearward edge, of the sole. The second working surface portion may extend from an edge of the sole to the middle of the working surface, between the forward edge and the rearward edge, of the sole.The first working surface portion, or part, may comprise 10-70 % of the working surface of the sole, and the second working surface portion may comprise 30-90% of the working surface of the sole. For example, the first working surface portion may comprise about 50% of the working surface of the sole, and the second working surface portion may comprise about 50% of the working surface of the sole.It is specified above that the shoe may comprise the sole. In an alternative, the working surface may be formed by a first working surface and a second working surface that together form the working surface. This means that the workings surface is formed by two separate parts, each mounted to the base body. The first part may thus form, or have, the first working surface portion of the sole, and the second part may form, or have, the second working surface portion. Worded differently, the sole may be manufactured from separate parts, a first part and a second part, joined, or bonded, or attached, to form the sole.The workings surface may be formed by an additional part, or portion, that may share surface roughness with either of the first working surface portion, or part, and the second working surface portion, or part.In another alternative, the shoe may comprise a holder configured, or arranged, to be attached to the base body and to the sole. Thereby a reliable fastening of the shoe is achieved, without reguiring the use of more complex technigues such as molding or adhesive. This also enables the mounting of the sole on the base body to take place in various locations such as on site near or in a paper machine. By manufacturing the base body and the sole separately from each other and joining them together by using the holder, a simplified manufacture of the shoe is thus achieved. In addition, this simplifies the mounting of the shoe in an extended nip roll.The sole, or the working surface, may be concave and conform to the convex shape of the counter roll. This allows the contact area between the working surface of the shoe and the counter roll to be increased further improving dewatering of a web of material.Alternatively, the sole, or the working surface, may be convex and conform, or match, the convex, or cylindrical, shape of the counter roll.In a further alternative, the sole, or the working surface, has a planar, or flat, working surface.The sole may be formed with a Shore hardness in the range of 50 Shore A to 65 Shore D, preferably in the range of 80 Shore A to 60 Shore D, more preferably in the range of 85 Shore A to 56 Shore D. In a further example, the Shore hardness of the sole may be in the range, of 90 Shore A to 60 Shore D, or in the range of 85 Shore A to 56 Shore D.These values correspond to the values discussed above in relation to the working surface, or shoe.The base body may be made from the same material as the sole. The material making up the base body may have different properties compared to the sole. For example, the material of the base body may have a different hardness compared to the sole. The Shore hardness of the sole may be higher than the Shore hardness of the base body. The Shore hardness of the base body may be higher than the Shore hardness of the sole. For example, the base body and the sole may both be made from the polymer material, and the Shore hardness of the sole may be higher than the Shore hardness of the base body. In one embodiment the base body may have a Shore A hardness in the range of 50-95 and the sole may have a Shore hardness in the range of 80 Shore A to 60 Shore D, such as in the range of 85 Shore A to 56 Shore D, or 90 Shore A to 56 Shore D.In a further alternative, the base body may be made from a different material compared to the sole. For example, the base body may be made from metal such as steel or aluminium. Other suitable materials for the base body include metal alloys such as bronze.The base body may be made from a composite material. For example, the composite material may comprise a base material and a filler material. The filler material may be a fibre material. Worded differently, the base body may be made from a fiber-reinforced polyurethane, or polymer. The fibers may be embedded in a polyurethane polymer matrix to form the composite material. The fibers may be natural fibers.Alternatively, the fibers may be synthetic fibers.It is understood that when the shoe is manufactured from the polymer material, such as polyurethane, the shoe may comprise one or more internal pressure chambers, forming a void or voids, in the shoe. The internal pressure chambers may be formed, or arranged, in the base body. The pressure chamber may have a longitudinal extension in transverse to the machine direction. The pressure chamber may be filled with a fluid, such as a liguid fluid, to adjust the pressure the extended nip roll applies on the belt, or jacket, or blanket, web and counter roll. Alternatively, to being filled with liguid fluid, the chambers may be filled with compressed air.It is specified above that the Shore hardness of the sole may be higher than the Shore hardness of the base body. Using a stiffer material for the sole may lead to a decreased reguired pressure in the chambers.In one example, the shoe may comprise at least a first pressure chamber and a second pressure chamber. By a first pressure chamber and a second pressure chamber the applied nip pressure between the shoe and the counter roll may be adjusted. By increasing the pressure in the first and the second internal pressure chamber the shoe expands at least in the shoe height direction, transverse to the machine direction. The working surface may be biased against the counter roll, and by increasing the height of the shoe a higher biasing force is applied by the shoe to the counter roll. This increases the nip pressure, or nip load, applied on to the web of material fed through the nip.The at least a first pressure chamber and a second pressure chamber may enclose different sized volumes. For example, the at least one first pressure chamber may enclose, or form, a first volume and the at least one second pressure chamber may enclose, or form, a second volume, wherein the first volume is greater than the second volume.Alternatively, the second volume may be greater than the first volume.It is understood that at least one first pressure chamber and the at least one second pressure chamber may be filled with a fluid, such as a liguid fluid, to adjust the pressure the extended nip roll applies on the belt, or jacket, or blanket, web and counter roll, and that the at least one first pressure chamber and the at least one second pressure chamber may be pressurized at different pressures.In a further alternative, the shoe may comprise more than two pressure chambers, such as three or four pressure chambers.The base body may comprise the internal pressure chamber, forming the void, in the shoe. This means that the sole, or working surface is free from any internal pressure chamber.It is specified above that the shoe may comprise one or more internal pressure chambers, forming a void, in the shoe, to adjust the pressure the extended nip roll applies on the blanket, web and counter roll.Additionally, or alternatively to the shoe comprising internal pressure chambers, the base body, or shoe holder, may also be connectable to a displacement device for displacing the base body, and the shoe, in a direction towards or away from, the blanket, web and counter roll. The displacement device may be a mechanical displacement device or a hydraulic displacement device or a pneumatic displacement device.It is specified above that the belt roll comprises a belt, or jacket. The belt may have an inside surface, or inner surface, and an outside surface, or outer surface. The inner surface faces the working surface of the shoe. The outer surface is arranged opposite the inner surface, and the outer surface faces, and contacts the web, or felt, at the nip. The inner surface and the outer surface form part of a belt body. The belt body may further comprise an intermediate layer arranged between the inner surface and the outer surface. The intermediate layer may be, or form, a reinforcing layer, or structure. Worded differently, the body may have a reinforcing layer, embedded into the belt body, between the inner surface and the outer surface. The belt may form a closed loop, or cylinder.The body may comprise an outer layer forming the outer surface of the body. The outer layer may have a thickness of at least 0.5 mm, preferably at least 1 mm, and most preferably at least 1.5 mm.The body may comprise an inner layer forming the inner surface of the body. The inner layer may have a thickness of at least 0.5 mm, preferably at least 1 mm, and most preferably at least 1.5 mm.The intermediate layer may have a thickness larger than that of the inner layer and / or outer layer.The belt may be an impermeable belt. In one embodiment the belt may be an impermeable belt which has a smooth surface on the side that faces the counter roll.Alternatively, the belt may be an impermeable belt which has a textured surface on the side that faces the counter roll.In an alternative to the belt being an impermeable belt, the belt may be a permeable belt. In one embodiment the belt may be a permeable belt which has a textured surface on the side that faces the counter roll, or the outside surface. Alternatively, the belt may be a permeable belt which has a smooth surface on the side that faces the counter roll, or the outside surface.The belt may have a Shore A hardness in the range of 60-100, preferably, a Shore A hardness 70-95, more preferably a Shore A hardness of 90-95.In one embodiment the inner surface of the belt has a surface roughness Ra that is less than 20 pm, preferably less than 6 pm, and more preferably less than 1 pm. The surface roughness of the inner surface of the belt may correspond, or match, the surface roughness of the working surface of the shoe. For example, the surface roughness of the inner surface of the belt may be in the range of 1-3 pm.It is specified above that a lubricating fluid layer may be arranged between the belt and the shoe. The lubricating fluid layer may be a lubricating liquid layer, formed by a liquid lubricant. It is understood that the lubricant may be applied to the inside surface, or inner surface, of the belt by a nozzle, and the nozzle may spray the lubricant onto the inside surface of the belt. The lubricant is thereby applied directly to the belt.Alternatively, a lubrication channel may be arranged to feed a lubricant directly to the working surface of the shoe. The shoe may thus comprise the lubrication channel. In addition, the lubrication channel may be arranged in the sole or both the sole and the base body. For example, the sole may comprise one or a plurality of channels that and one or a plurality of openings to feed the oil to the working surface and the inside surface of the belt. The one or plurality of lubrication channels may in turn be in fluid connection with a source or lubricant such as a pump.The sole, or the working surface, may comprise a lubricant pocket. The lubricant pocket may be formed by surface recess in the working surface, that extends in the machine direction and in the longitudinal direction of the shoe. The lubricant pocket may be connected to the source of lubricant by the lubricant channel or channels.The lubricant pocket may be arranged adjacent, or about, the forward edge of the shoe. Worded differently, the lubricant pocket may be arranged on the shoe about the nip entrance of the extended nip roll.In one alternative the lubricant is an oil lubricant in the form of a hydraulic oil lubricant. For example, the lubricant may be Mobil DTE 10 Excel oil, manufactured and / or sold by Mobil and the ExxonMobil company.It is specified above that the length of the nip in the machine direction may be in the range of 5 mm to 120 mm, preferably in the range of 15 mm to 120 mm. In one example the length of the nip is more than 120 mm in the machine direction. Preferably, the length of the nip in the machine direction is in the range of 40 mm to 120 mm.It is further understood that the length of the nip in the machine direction may correspond, or match, the width of the shoe in the machine direction. The width of the shoe may be measured between the forward edge and the rearward edge of the shoe, transverse to the forward edge and the rearward edge. The width of the shoe may be in the range of 5mm to 120 mm, preferably 40 mm to 120 mm.The lubricant pocket may be located, or positioned, within the first 40 % of the length of the nip, relative to the forward edge. It is understood that and the pressure in the nip reaches its highest value within the first 40 % of the length of the nip. It is thereby advantageous to arrange the pocket here to reduce the risk of damage to the belt due to insufficient lubricant being provided.The lubricant pocket may have an extension in the machine direction which is in the range of 3 mm to 9 mm, preferably 4 mm to 8 mm. The pocket may be designed to become gradually shallower towards the downstream end of the pocket, in a direction towards the rearward edge of the shoe.In addition, the belt roll may also be provided with an evacuation system for removing such lubricant that has already been used such that spent lubricant fluid may be continuously replaced by fresh lubricant fluid (e.g. oil).For example, a lubricant scraper may be arranged downstream the nip, in a machine direction, the scraper arranged to remove lubricant from the inside surface of the belt, at a position downstream the nip.It is specified above that the shoe may comprise a base body and a sole and that the sole may form, or comprise, the working surface. The sole be in the form of a layer of material arranged, or attached, to the base body. The sole may thereby have a thickness of 5-50 mm, preferably 15-35 mm, and most preferably 20-30 mm. The working surface, or the sole, may have a length in the machine direction in the range of 50-150 mm.In a further aspect of the proposed technology, a belt roll arranged to cooperate with, and apply a force to a counter roll, and together with the counter roll form a nip press, is provided wherein the belt roll comprises: the shoe according to the first aspect, a flexible belt, or sleeve, or jacket, and a lubricating fluid layer arranged between the belt and the shoe, wherein the shoe contacts the lubricating fluid layer and the belt and presses the belt towards, or against, the counter roll The belt roll may comprise a shoe support for mounting, or supporting, the shoe to the belt roll.The belt roll may comprise a support to mount the shoe to. The support may thereby fixate, or hold, the shoe relative to the support. The support may be formed, or have the shape of, a channel. The channel may have a first wall facing a second wall, wherein the first wall and the second wall are connected by a bottom section, or bottom. The channel, or groove, is thereby open, or does not comprise a wall, in the direction facing the belt, or counter roll.It is specified above that the belt roll may comprise a lubricant spray nozzle. The lubricant spray nozzle is arranged to spray a lubricant onto an inside surface of the belt, to cover the inside surface of the belt that faces, and comes into contact with, the shoe as the belt roll rotates. The lubricant spray nozzle may be connected to a conduit that provides pressurized lubricant.It is understood that the inside surface of the belt may have a surface roughness that corresponds, or matches, the surface roughness of the working surface of the shoe. The combination of surfaces roughness of the belt and the shoe further reduces wear and damage to the belt and shoe.In a third aspect an extended nip press is provided, the nip press comprising the belt roll according to the second aspect and a counter roll, is provided. It is understood that the counter roll may be a Yankee dryer roll or cylinder. A Yankee roll, or Yankee dryer, is a pressure vessel used in the production of machine glazed (MG) and tissue paper. The Yankee roll is arranged to be internally heated and applies heat to the paper web to remove moisture.In a further aspect, a paper making machine is provided, wherein the paper machine comprises belt roll according to the second aspect, or an extended nip press according to the third aspect, is provided. It is understood that a paper, board, pulp, or tissue machine may comprise one, or more than one, press that comprises a belt roll as described herein.Brief description of the drawingsA more complete understanding of the abovementioned and other features and advantages of the proposed technology will be apparent from the following detailed description of preferred embodiments in conjunction with the appended drawings, wherein:Fig. 1 shows a schematic sideview of a belt roll cooperating with a counter roll to form a press nip;Figs. 2A-2B shows an enlarged partial side view of the nip press with the shoe mounted to a shoe support;Figs. 3A-3B shows a shoe in a first state and a second state;Figs. 4A-4B shows two examples of shoes with different working surface shapes; andFigs. 5A-5C shows three different examples of shoes with a sole arranged to a base body of the shoe.Description of the drawingsFig. 1 shows a schematic sideview of a belt roll 10 cooperating with a counter roll 12. The belt roll 10 and the counter roll 12 together form a press 1, for pressing a web of material 14, such as a paper web 14, between the belt roll 10 and the counter roll 12. The belt roll 10 and the counter roll 12 rotate in opposite rotational directions around a respective rotation axis 16, 18. The counter roll 12 rotates counterclockwise around a first rotation axis 16, or counter roll rotation axis 16, and the belt roll 10 rotates clockwise around a second rotation axis 18, or belt roll rotation axis 18. The belt roll 10 is formed by a stationary member 24, or support 24, and a belt 26, or jacket 26, or sleeve26, that rotates around the stationary member 24 and the belt roll rotation axis 18. The belt 26 is thereby a flexible belt 26 and is made from a polymer material.A web of material 14 is fed through the press 1 where it is compressed between the belt roll 10 and the counter roll 12. The region wherein the web of material 14 is compressed is referred to as the nip 28. The web of material 14 is formed by a paper material that is sandwiched between two felts (not shown).The belt roll 10 further has a shoe 30 that is mounted to a shoe support 32 that supports, the shoe 30. The shoe support 32 forms part of the stationary member 24. The shoe 30 applies a pressure, and a force, on the belt 26 in a direction towards the counter roll rotation axis 16 of the counter roll 12. Thereby the web of material 14 is compressed between the counter roll 16, the belt 26 and the shoe 30 of the belt roll 10. At the contact, a contact region is formed, by a contact surface of the shoe and by a contact surface of the belt. This will be further explained in relation to Figs.2A-2B.Fig. 2A shows that the belt has an inside surface 40, or inner surface 40, and an outside surface 42, or outer surface 42. The inner surface 40 faces and contacts the working surface 44 of the shoe 30. The outer surface 42 is arranged opposite the inner surface 40, and the outer surface faces 42, and contacts, the web of material 14 at the nip 28. The inner surface 40 and the outer surface 42 form part of a belt body. The belt 26 is normally connected to end walls that are rotatably arranged about the rotation axis of the belt roll so that the extended belt and the belt roll is able to rotate (not shown). Suitably, the belt roll 10 is connected to a source of pressurized air so that an enclosed space formed by the belt and the end walls can be filled with pressurized air.Fig. 2A shows that the machine direction X, or X-direction X, is parallel, to the web of material 14. In addition, a Y-direction Y is shown, transverse to the machine direction X. Transverse to the X-direction X and the Y-direction Y is the longitudinal extension direction, or cross-machine direction 20.Fig. 2A further shows that the belt roll 10 comprises a shoe support 32 that supports the shoe 30. The shoe support 32 thereby fixates, or holds, the shoe 30 relative to the shoe support 32. The shoe support 32 forms a channel. The channel has a first wall 46 facing a second wall 48, wherein the first wall 46 and the second wall 48 are connected by a third wall 50, or bottom 50. Opposite the third wall 50, or bottom 50, the channel 34 is open and arranged, or configured, to receive the shoe 30. The channel 34 thus conforms to the shape of the shoe 30, and in particular to the lower part, or portion, of the shoe. The channel 34, or groove 34, extends in a longitudinal direction 20, or crossmachine direction 20.The groove is open at the side facing the counter roller, or the nip. The support thus supports the shoe 30 and maintains the shoe 30 in position relative to the nip 28, or shoe support 32, and allows for the shoe 30 to extend only, or primarily, in a direction towards the counter roll 12, the direction being parallel to the Y-direction Y.The shoe 32 has a forward edge 52 and a rearward edge 54. The forward edge 52 is arranged, or located, about the entrance of the nip 28, and the rearward edge 54 is arranged about the exit of the nip 28. The belt 26 that passes through the nip 28, or temporarily forms a contact of the nip 28 relative to the web of material 14, in the machine direction X, or X-direction X, will thus first pass the forward edge 52, and subseguently pass the rearward edge 54. Thereby a section of the belt contacts the forward edge 52 first, and contacts the rearward edge 54 last. The belt thus moves from left to right in the Fig. 2A.In addition, Fig. 2A shows that the shoe 30 has two internal pressure chambers 56, 58, that forms voids, in the shoe 30. The two internal pressure chambers 56, 58, or first chamber 56 and second chamber 58 are arranged to be pressurized by a fluid.Fig. 2B shows that when the internal pressure chambers 56, 58 are pressurized with the fluid the chambers 56, 58 will expand. This in turn leads to the shoe 30 expanding. The channel 34 will limit expansion of the shoe 30 in the directions of the first wall 46, the second wall 48 and the third wall 50. The opening opposite the third wall 50, or bottom 50, will however, allow for expansion of the shoe 30 in the Y-direction, and the height of the shoe 30 will increase. This results in that the pressure applied by the working surface 44 of the shoe 30 on the belt 26 will increase, and thereby the nip load force will also increase. Fig.2B also shows that the inside surface 40 of the belt has a lubricating layer 22 applied to the surface.Fig. 3A shows the isolated views of the shoe 30 in a first state, or unexpanded state, and Fig. 3B shows the shoe 30 in a second state, or expanded state. In the first state the first chamber 56 and the second chamber 58 are not pressurized. In Fig. 3B the pressure is increased in the first chamber 56 and the second chamber 58 and the height 60 of the shoe is increase whereas the width is maintained or kept the same, due to the shoe's expansion being limited by the first wall 46 and the second wall 48 together with the third wall 50, or bottom 50. The shoe shown in Figs. 1-3 has a planar, or straight, working surface 44.Figs. 4A-4B shows alternative shoes 30 wherein Fig. 3A shows that the shoe 30 has a concave working surface 44. The concave working surface 44 extends the contact area between the workings surface 44 and the belt and the counter roll. The shoe in Fig. 4A may thereby be mounted, or arranged, to an extended nip (not shown). Fig. 4B shows that the working surface 44 of the shoe 30 has a convex shaped working surface 44. The convex working surface 44 reduces the contact area between the workings surface 44 of the shoe 30 and the belt and the counter roll. This results in an increased nip load of a press employing the shoe 30 of Fig. 4B since the contact area is decreased, or minimized.Fig. 5A shows an alternative shoe 30 that comprises a sole 64 and a base body 66. The sole 64 is positioned, or located, at a top of the shoe 30. When the shoe 30 is mounted to the shoe support and the belt roll, the top of the shoe faces and contacts the belt. The base body 66 is positioned, or located, oppositely from the sole 64 of the shoe 30. The base body 66 comprises the two internal pressure chambers 56, 58. The sole 64 has, or comprises, the working surface 44 arranged to contact the belt. The shoe 30 in Fig. 5B thereby comprises two separate sole parts 68, 70 that together form the sole 64 with the working surface 44. The sole 64 and the base body 66 are made from a polymer material, in the form of polyurethane, and the sole 64 has a Shore hardness that is higher than the Shore hardness of the base body 66.The first sole part 68 and the second sole part 70 are attached to the base body 66. The sole 64 can thereby be manufactured from separate parts, or a first part 68 and a second part 70, that is joined, or bonded, or attached, to the base body 66, to form the sole 64. The first part 68 and the second part 70 are manufactured from the same material, however has different Shore hardness values. In addition, the surface roughness of the first part 68 and the second part 70 are different or the same.Fig. 5C shows a further example wherein the sole 64 is formed by an additional third part, or portion, 72 that is positioned, or located, between the first part, or portion, 68 and the second part, or portion, 70. The third part 72 is made from the same type of polymer material, however, the Shore hardness and / or the surface roughness of the third part 72 can be different from that of the first part 68 and / or the second part 72.Item list1 press, or nip press10 belt roll12 counter roll14 web of material16 counter roll rotation axis18 belt roll rotation axis20 longitudinal direction, cross-machine direction 22 lubricating layer2224 stationary member, or support26 belt, or jacket, or sleeve,28 press nip30 shoe32 shoe support34 channel, groove40 belt inside surface, inner surface 42 belt outside surface, outer surface 44 shoe working surface46 first wall48 second wall50 third wall, bottom52 forward edge54 rearward edge56 first chamber58 second chamber60 shoe height62 shoe width64 sole66 base body68 sole first part, or portion70 sole second part, or portion72 sole third part, or portionX machine direction, or X-direction Y Y-direction

Claims

1. A press shoe (30) for a paper making machine, arranged to be mounted in, or installed into, a belt, or sleeve, or jacket, roll (10), wherein the shoe (30) comprises:-a working surface (44), or sole (64), or contact surface, arranged to face and contact a belt, or sleeve, or jacket (26), and cooperate with a counter roll (12), to form a nip press (1), wherein the working surface (44) of the shoe (30) is made from a polymer material, and the working surface has a surface roughness Ra that is less than 20 pm, preferably less than 6 pm, and more preferably less than 1 pm.

2. The shoe of claim 1, wherein the shoe (30) has a Shore hardness in the range of 50 Shore A to 65 Shore D, preferably in the range of 80 Shore A to 60 Shore D, more preferably in the range of 85 Shore A to 56 Shore D.

3. The shoe of claim 1 or 2, wherein the polymer material is a synthetic polymer, or synthetic rubber, material, such as polyurethane.

4. The shoe of any claim 1-3, wherein the shoe (30) is made from a composite polymer material comprising a polymer matrix material and reinforcing fibers mixed, or dispersed into, the polymer matrix material.

5. The shoe of any claim 1-4, wherein the shoe (30) comprises at least one internal pressure chamber (56, 58), that is arranged to be pressurized such that the shoe (30) expands in at least a height direction (Y) of the shoe (30).

6. The shoe of claims 1-5, wherein the shoe (30) is formed by a base body (66) and a sole (68), wherein the sole (68) comprises the working surface (44).

7. The shoe of claim 6, wherein the material of the base body (66) has a different hardness compared to the material of the sole (64).

8. The shoe of claim 6-7, wherein the base body (66) has a Shore hardness of 50-95 Shore A and the sole (64) has a Shore hardness of 85 Shore A to 56 Shore D.

9. The shoe of claim 6, wherein the sole (64) has a thickness in the range of 5 mm — 30 mm.

10. The shoe of claim 1-9, wherein the shoe (30) has a longitudinal extension, transverse to a machine direction, or cross-machine direction (20), that is in the range of 1200 mm -8000 mm, preferably in the range of 2500 mm —8000 mm.

11. The shoe of claim 6, wherein the sole (64) comprises: a first working surface part, or portion, (68) and a second working surface part, or portion, (70) wherein the first working surface part, or portion, (68) has a surface roughness Ra that is less than 20 μm, preferably less than 6 μm, and more preferably less than 1 μm, and wherein the second working surface part, or portion, (70) has a different surface roughness, preferably a surface roughness above the surface roughness of the first working surface part , or portion, (68).

12. A belt roll (10) arranged to cooperate with, and apply a force to a counter roll (12), and together with the counter roll form a press nip (1), wherein the belt roll (10) comprises:the shoe (30) according to any of claims 1-11, and a flexible belt, or sleeve, or jacket, (26) anda lubricating fluid layer (22) arranged between the belt (26) and the shoe (30), wherein the shoe (30) contacts the lubricating fluid layer (22) and the belt (26) and presses the belt (26) towards, or against, the counter roll (12).

13. The belt roll (10) claim 12, wherein the belt roll (10) comprises a shoe support (32) for mounting, or supporting, the shoe (30).

14. The belt roll (10) of any claim 12-13, wherein the belt roll (10) comprises a lubricant spray nozzle arranged to spray a lubricant onto an inside surface (40) of the belt (26), wherein the inside surface (40) of the belt faces, and contacts, the shoe (30) as the belt roll (10) rotates around a rotation axis (18).

15. The belt roll (10) of claim 11-14, wherein the inside surface (40) of the belt has a surface roughness that corresponds, or matches, the surface roughness of the working surface (44) of the shoe (30).

16. A paper making machine for manufacturing paper from a pulp, the paper making machine comprising the belt roll (10) according to any claim 12-15.