CN1039929C - Impulse dryer roll with shell of high thermal diffusivity - Google Patents

Impulse dryer roll with shell of high thermal diffusivity Download PDF

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CN1039929C
CN1039929C CN94193754A CN94193754A CN1039929C CN 1039929 C CN1039929 C CN 1039929C CN 94193754 A CN94193754 A CN 94193754A CN 94193754 A CN94193754 A CN 94193754A CN 1039929 C CN1039929 C CN 1039929C
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roller
shell
paper web
nip
thermal diffusivity
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CN94193754A
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CN1133076A (en
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格雷戈里·L·韦德尔
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Beloit Technologies Inc
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Beloit Technologies Inc
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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
    • 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
    • D21F3/0281—Wet presses in combination with a dryer roll
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/02—Drying on cylinders
    • D21F5/022—Heating the cylinders
    • D21F5/024—Heating the cylinders using electrical means
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00—Calenders; Smoothing apparatus
    • D21G1/02—Rolls; Their bearings
    • D21G1/0253—Heating or cooling the rolls; Regulating the temperature
    • D21G1/028—Heating or cooling the rolls; Regulating the temperature using electrical means

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Abstract

In a paper-making machine a roll (22) is composed of two parts: a metallic base shell (38), which is constructed of conventional spun-cast steel alloy; and a thin outer shell (40) constructed of a material of high thermal diffusivity. The outer shell (40) is one to a few tenths of an inch thick and is in intimate contact with the surface of the steel alloy base shell (38). Typical materials of high thermal diffusivity for uses in the outer shell (40) are copper and aluminum. The roll (22) may be formed by flame spraying a layer of copper approximately two-tenths of an inch thick on the surface of a steel alloy base shell (38). The roll (22) is employed where improved heat transfer to a paper web is desired for example in an impulse paper dryer, or in a calendar.

Description

Impulse dryer roll with shell of high thermal diffusivity
The present invention relates to paper machine and calender, particularly relate to the roller that uses in the paper machine to the web transfers heat.More particularly, the present invention relates to a kind of improvement that is used for paper machine or calender to the heating roller of the heat transmission of paper web and used the drier of this roller.
Papermaking is a capital intensive industry.In order to boost productivity, people make great efforts to improve by the width of the paper web that increases the paper machine output output of paper, and the trend that another kind is boosted productivity is the speed that improves by the paper web of machine.The width of paper web can increase by the width that increases paper machine and paper processing roller.The speed that increases papermaking has but produced a problem at the drying section of paper machine, and the speed one of paper web increases, and just descends to the heat of doing web transfers from each drying roller.Therefore, in order to adapt to higher web speed, the drying section of paper machine just is compelled to do longlyer.
A kind of solution of longer drying section is to adopt the impulse dryer device.The impulse dryer device has adopted a kind of high temperature roller that is heated to 232 ℃ (450) or higher temperature.Form the nip (nip) of a lengthening between this a warmed-up roller and the cambered surface profiled sheeting, paper web is contacted with the high temperature face of this roller.The paper web back side is a press felt (press felt), and press felt covers a woollen blanket again, is the lubricating film on the cambered surface profiled sheeting below the woollen blanket.Can reduce the length of drying section of paper machine significantly by the impulse dryer device that uses this roller nip that extended.
Further improve this impulse dryer device and just need to increase the heat conduction between roller and the paper web.Increasing the roller surface temperature will increase the temperature of whole roller.This is harmful to for roller intensity.The roller temperature that has increased also can make the use of high supporting mechanism in the inside that depends on hydraulic pressure (internal support mechanisms) become complicated.And high temperature can cause the deeply worried of press felt, the paper surface fiber peel off excessive roller head stress and bearing running hot.In the U.S. Pat 4,324,631 of authorizing Wahren, can find, make the impulse dryer roller with a kind of material and be good with high thermal conductance.Wah-ren has also instructed, and it is very good adopting the roller that hangs down the surface heat conductivity to obtain high surface temperature, and Wahren has advised a kind of material alternative condition of roller surface layer at least that is used for, and he does not think that aluminium is better than steel or nickel.Wahren thinks that copper is not suitable for his roller.
Authorize the U.S. Pat 4,631,794 of Riihinen and described a kind of induction heating roller that is used for calender.This roller adopts a kind of nonmagnetic insulating barrier between ferromagnetic layer and the interior roller core outside it.Riihinen provides the eddy-current heating of roller in the calender, and can enter in the roller so that high control in carrying out, but not have openly how to use the pyroconductivity that has improved to improve heat transfer.
Authorize the U.S. Pat 4 of Busker etc., 738,752 have advised a kind of pressure roller that long nip press carries out platen that adds that is used in a heating, and it comprises one first coaxial layer and second coaxial layer around this ground floor extension, and the coefficient of heat conduction of the second layer is bigger than ground floor.Ground floor is a kind of material of low heat conduction coefficient, and the second layer is a metal.He advises that further ground floor is a pottery, and the second layer is a metal.
This second outer field thickness of suggestion such as Busker is in 0.0127-0.127cm (0.005-0.050 inch) scope.Busker etc. do not have the open suitable thickness that how to calculate the metal shell on the Metal Substrate shell in, are not taught in the importance of heat diffusivity when selecting sheathing material and outer casing thickness yet.
People are needed to be a kind of roller that having of impulse dryer device or calender improved capacity of heat transmission that can be used for.
An object of the present invention is to provide a kind of the increase to the heat conducting impulse dryer device of heated paper web roller.
Another object of the present invention provides a kind of roller that is used for a calender, and it provides the heat conduction of increase to a paper web with a given roller surface temperature.
A further purpose of the present invention provides a kind of roller of the drying section of the paper machine of short drying section of a kind of needs that is used for.
Of the present invention one further purpose provide a roller that is used for an impulse dryer device, it has reduced peeling off of paper surface fiber.
Of the present invention one further purpose provide a kind of roller that is used for an impulse dryer device, it has reduced roller head stress.
A further object of the invention provides a kind of impulse dryer device that comprises aforementioned roller.
Roller of the present invention is made up of two parts.A part is a Metal Substrate shell, and it is made of common centrifugal casting steel alloy.Second portion is made of several centimetres of (a few tenths of inch) thick thin outer crusts of a branch, and it closely contacts with this steel alloy base shell surface.
This shell is made of a kind of material of high thermal diffusivity, and thermal diffusivity is directly proportional with pyroconductivity, and is inversely proportional to specific heat and density of material.The example of high thermoconductivity is copper and aluminium.
A kind of method of making roller of the present invention is about 0.51 centimetre (2/10ths inches) the thick copper of surperficial flame injection one deck at a roller.The hot pressing district that this roller is used for the lengthening of an impulse dryer device, the nip of this extension is formed by a cambered surface profiled sheeting.This cambered surface profiled sheeting has the bigger slightly smooth surface in surface of ratio of curvature roller of the present invention.With the speed that equals roller surface speed one extended nip woollen blanket is pulled through above this cambered surface profiled sheeting surface.One paper web has one to press blanket between woollen blanket and paper web near the surface operation of roller.The effect of cambered surface profiled sheeting is to keep paper web to be attached to peripheral the preceding paragraph distance of roller, and diameter is this section peripheral distance the chances are 25.4cm (ten inches) on the roller of 1.59m (five feet).The roller rotation produces the superficial velocity of per minute 914m (3, the 000 feet) order of magnitude.The woollen blanket, pressure blanket and the paper web that add long nip press all pass through this roller with an identical speed.
This roller is to be made of the double wall metallic cylinder, and the thickness of typical this cylinder is several inches.One induction heater heats the roller surface of the upstream of the nip of this lengthening.If conduction is analyzed and will be observed to the heat between beam barrel and the paper web, have only the most external of roller experiencing a kind of fluctuating temperature.Be heated to 232 ℃ (450 ° of Fahrenheits) if roller surface is sensed, then the inside of whole roller also will reach 232 ℃ of mean temperatures (450).
The roller surface temperature that contacts with paper web may be reduced to 93 ℃ (200 °F) or 149 ℃ (300 °F).But this temperature fluctuation occurs over just in the roller top 0.25-0.76cm (1/10th to 3/10ths inches).Therefore, effective conduction portion of this roller is a thin outer shroud.In common roller, increase heat conducting method and can only be and improve roller temperature, increase nip length or reduce web speed.Because these three kinds of approach all need to increase cost and shortcoming is all arranged, so the present invention makes its copper layer that has a thickness accurate Calculation increase its thermal diffusivity when making roller, thereby increases the heat conduction between roller and the paper web.
Impulse dryer device of the present invention forms a nip between the roller of aforementioned invention and co-operating member, its length along a first direction is L rice (foot).Paper web passes through nip with the superficial velocity of S rice/hour (S foot/hour) along first direction.The surface of roller is heated during by nip when paper web, and hot heat transferred paper web.The shell of roller is made by second metal that thermal diffusivity is higher than 0.09 square metre/hour (1 square feet/hour), and its radial thickness X rice (foot) is definite by following formula, X = 4 aL S
Wherein, a is the thermal diffusivity of shell.
From below in conjunction with accompanying drawing to can clearly be seen that further purpose of the present invention, feature and advantage the detailed description that the present invention did.
Fig. 1 is the large tracts of land long nip press of a sketch form or the nip type that extended, has adopted the profile of the paper machine of two-layer drum of the present invention.
Fig. 2 is the large tracts of land long nip press of a sketch form or the nip type that extended, adopt one strained add the long nip press woollen blanket and adopt the profile of the paper machine of roller shown in Figure 1.
Fig. 3 is at the curve map of the different depth place on the surface of roller shown in Figure 1 temperature to the time.
Fig. 4 be a sketch form employing the profile of one calender of two-layer drum of the present invention.
Concrete with reference to figure 1-4, wherein identical label is represented similar parts.Fig. 1 shows an impulse dryer device 20.This impulse dryer device 20 comprises that one and one cambered surface profiled sheeting 24 forms the pressure roller 22 of a nip 26, and the face towards roller 22 on the cambered surface profiled sheeting 24 is a concave surface, and is mounted to and makes it press to roller 22.Between roller 22 and cambered surface profiled sheeting 24, form nip 26.Paper web 28 passes nip 26 and is subjected to an extruding force in the time of an elongated segment.One presses blanket 32 in 28 times operations of paper web, and nip is being passed under the pressure blanket 32 on 24 in an endless belt 30.
Between cambered surface profiled sheeting 24 and endless belt 30, add oil, between endless belt 30 and cambered surface profiled sheeting 24, constitute the moving oil film wedge (fluid wedge) of a fluid.This oil film wedge is to web transfers pressure, and lubricated simultaneously paper web 28 is by the motion of nip 26.Press blanket 32 below paper web 28, to pass nip 26 above the endless belt 30.Paper web 28, pressure blanket 32 and endless belt 30 and roller 22 are cooperating, thereby are driven with same speed.Like this, paper web 28 can not be subjected to significant shearing force, because all do not having relative motion on the plane of paper web 28 and pressure blanket 32 and on the surface 34 of pressure roller 22.What therefore paper web 28 was subjected to when passing the nip 26 of lengthening is pressure basically.The effect of this pressure is that paper web is closely contacted with the surface 34 of pressure roller 22.
Paper web 28 can carry out heat exchange with the tight surface 34 that makes roller 22 that contacts of roller surface 34 under pressure rapidly with paper web 28.Rapid heat conduction between roller 22 and the paper web 28 has produced a drying mechanism that is not entirely understood, and this drying mechanism is the characteristics of this impulse dryer device.The rapid heating of paper web makes some contained in paper web water evaporations.The steam that produces in the water from paper web constrains between the surface 34 and paper web 28 of roller 22.The paper web 28 that passes through of the unique channel that steam is escaped enters pressure blanket 32.Steam enters the downward rapid movement of pressing blanket 32 downwards from the upper surface of paper web 28 to have and is blown into effect in the woollen blanket 32 with being contained in water the paper web 28.This process, promptly impulse dryer has caused moisture to be discharged rapidly from paper web 28.
Because the structure of roller 22, the pressure roller 22 of impulse dryer device 20 has improved the efficient of common impulse dryer device.Roller 22 has a Metal Substrate shell 38 that is made of common steel alloy.This base shell 38 is covered by the shell 40 that a material by a kind of high thermal diffusivity (for example copper) constitutes.Should be noted that this roller is not to illustrate in accurate ratio in the drawings, exaggerated the relative thickness of basic shell and shell for convenience of description.Shell 40 closely is connected in the outer surface 42 of basic shell 38.Metal Substrate shell 38 forms the support structure of shell 40.The thermal diffusivity of the outside copper layer that has increased can make the effective heat conduction between roller 22 and the paper web 28 double.Typical impulse dryer device comprises a nip, and the roller surface temperature surpasses 93 ℃-149 ℃ (200-300 °F) in nip, at 232-288 ℃ (450-550 °F).Typical impulse dryer device can adopt the nip of a lengthening, with a cambered surface profiled sheeting one waterproof woollen blanket is pressed on the roller of an eddy-current heating.When wet web passed through nip, surperficial high temperature was rapidly to its heating and softening paper fiber.This has strengthened the discharge of water widely, and makes paper produce intensity.
Adopt thin outer 40 of raising thermal diffusivity to improve capacity of heat transmission, make the impulse dryer device to design according to the specific beneficial effect that will obtain.At first, the surface temperature of roller 22 can be lowered and the heating of same degree still can be provided.This has overcome the some problems relevant with housing high temperature.High temperature can cause that the dabbing blanket is deeply worried, paper fiber spin-off, the excessive and bearing running hot of roller head stress.Secondly, can provide more heat to paper web, so that discharge more juicy.The 3rd, can improve the speed of paper web 28, keep constant input and drying effect simultaneously.In the optimal design of reality, adopt the high diffusivity shell pressure roller 22 can be with three all advantages, the drying more completely of promptly lower roller temperature, the higher speed of service and paper web 28 combines.
Fig. 1 be along the employing of paper paper web 28 travel directions interceptings the profile of one impulse dryer device 20 of improved pressure roller 22.The people who is proficient in paper industry knows, paper web 28 at the width on the transverse machine usually between 2.54-10.16cm (100 to 400 inches), the element of impulse dryer device, for example roller 22 is longer usually, this is the needs of some function.Endless belt 30 and support 44 thereof are common, in U.S. Pat 4,673, describe in more detail among 461 (Ro-erig etc.).The endless belt is a continuous loop, and it has a transverse machine width bigger than pressure roller 22, thereby end, endless belt (not shown) can be sealed in the round sealed device (illustrating), so just nip lubricating oil is remained in the endless belt 30 of sealing.A static beam 33 is arranged in endless belt 30.This beam supports cambered surface profiled sheeting 24, one pistons 37 by a hydraulic piston 35 adjustablely and is positioned in the chamber 35.The cambered surface profiled sheeting is supported on the roller pin 39 rotationally, and this roller pin crouches in down the groove and up the groove on the piston 37 in cambered surface profiled sheeting 24.Piston is upwards pressed by the fluid pressure in the chamber 35 below it, chamber be shaped as an elongated slot, accept piston slidably, and extend to the overall with of machine at the cambered surface profiled sheeting for 24 times.Endless belt 30 is by the side rails 41 and 43 of bending, upper rail 45 and 47 and lower guideway 49 guiding.These guide rail adjustable grounds are installed on the beam 33, and effect is to stablize endless belt 30 when starting.If fluctuation or unstable, endless belt 30 is also stablized by guide rail in normal operation.
In a single day endless belt 30 enters the speed of service, and except at nip 26 those sections that pass between cambered surface profiled sheeting 24 and the roller 22, centrifugal force makes it be the nature circle.Centrifugal force often remained on band and leaves guide rail 41,43,45,47 and 49 a bit of distances when therefore, speed was got up.
Pressing blanket 32 to be supported on one sends on a roller 46 and the pressure blanket outlet roller 48.It is 0.6m (two feet) that the diameter of blanket roller 46 and outlet roller 48 is pressed in typical input, and the diameter of corresponding pressure roller is 1.5m (five feet). Roller 46 and 48 effect are to press blanket to take the input position that makes its nip that passes impulse dryer device 20 26 to.Press blanket 32 to leave outlet roller 48 backs and handled by a felt dryer (not shown), felt dryer is discharged water and too much steam from woollen blanket 32, and woollen blanket ability is returned and reused through sending into roller 46 then.
Pressure roller 22 shown in Fig. 1 used one have one non-rotating in high controlling organization 50 in the hydraulic pressure of high brace summer 52.High brace summer has one to piston chamber's 56 fuel feeding in being somebody's turn to do, to promote the oil supplying hole 54 that piston 58 withstands the inner surface 60 of Metal Substrate shell 38.Effect along center sill or axle 50 pistons that are spaced 58 is to provide a constant compression force between pressure roller 22 and cambered surface profiled sheeting 24.Simply show an induction heater 62 among Fig. 1.It has a coil 64 that passes to high frequency electric.This induction heater 62 is general types, and it is used the high frequency alternating current and produces concussion magnetic field, thereby produces vortex flow in surface 40 and roller 22.This induced-current causes resistance heated in surface 40, thereby is heated temperature required.
From heat conducting viewpoint, housing 40 is " semo-infinite plate (Semi-in-finite plate) seemingly.This is because a certain fragment of roller has only little time to be in the nip.By outside eddy-current heating housing 40, make whole roller with 60 to outside 34 temperature operations equably internally, but on a thin skin, temperature is cyclic fluctuation.This outer field effective depth can be estimated by following formula: X = 4 aL S
In the formula:
X=wherein experiences the degree of depth of the layer of temperature cycle variation, the m of unit (ft)
The superficial velocity of S=pressure roller, the m/hr of unit (ft/hr)
The L=nip length, the m of unit (ft)
The thermal diffusivity of a=outer surface, the m of unit 2/ hr (ft 2/ hr)
This depth estimation is to carry out under the prerequisite of this surface experience step variations in temperature of hypothesis., in fact this variation is not remarkable like this, and therefore above-mentioned estimation is on the big face.
Fig. 3 is a curve map, is illustrated in 3 upward temperature fluctuations in time going deep into the degree of depth on the roller surface in succession.Vertical axis is a temperature among Fig. 3, and trunnion axis is the time.Uppermost curve 66 expression roller surface temperature over time.Because the diameter of roller 22 is approximately 1.59m (5 feet), its girth is approximately 4.88m (16 feet).Nip 26 long 25.4cm (10 inches) shown in Figure 1, its knot are that about 5 percent of its rotational time is exposed to paper web 28.Upper curve 66 has a sawtooth waveforms shape 68 that repeats, the surface temperature that its expression roller 22 rotates a circle.
On the curve of Fig. 3, the surface 34 and paper web 28 contact points of the initial point 70 expression rollers 22 that temperature descends suddenly, on the yardstick of Fig. 3, all paper web contact time is 5 percent of a wavelength 68, it is instantaneous basically that this surface temperature descends.Then, the surface 34 of roller 22 is keeping paper web 28 by contact the temperature when being heated with roller.
When this lip-deep 1: 72 when from nip, coming out because heat passes to this low-temperature surface from roller is inner, the temperature of this point raises gradually.At last, when this roller surface process induction heater 62, sharply rise in point 74 place's temperature.Temperature keeps constant then, up to contacting with paper web 28 once more at 70 places.
The temperature curve of second curve 75 expression on any point of surface 34 certain depths of roller 22.The wavelength 76 of second curve 75 is identical with the wavelength 68 of surface temperature curve 66.Yet because curve 75 represented points are had a few distance from the surface, variation of temperature is not so precipitous.
The wavelength 80 of the 3rd curve 78 is identical with wavelength 76,68, and influenced by the velocity of rotation of roller 22.The representative of this curve than axis 75 from roller surface darker a bit, show the more depths in roller owing to periodically contact and sensed heater 62 heats caused variations in temperature and how to weaken gradually with paper web.
The 4th curve 82 shows a temperature in time and invariable situation.The degree of depth roughly of not having temperature fluctuation that its representative is calculated according to following formula.It also is the degree of depth that THERMAL DIFFUSIBILITY recedes into the background for the heat conduction of regulating between roller 22 and the paper web 28.
Thermal diffusion (a) is defined as follows: a = K Pc
In the formula:
The a=thermal diffusivity
The K=pyroconductivity
C=specific heat
P=density
Alloy cast iron shell thermal diffusivity only is about 0.66m 2/ hr (0.6-0.7ft 2/ hr), and the thermal diffusivity of aluminium is 3.3, copper is approximately 4.4.
Reference table 1 has different diffusivity values in the hurdle 1; 0.065m 2/ hr (0.7ft 2/ hr) roughly corresponding to the general material that constitutes pressure roller.Thermal diffusivity 0.28m 2/ hr (3ft 2/ hr) corresponding to aluminium, thermal diffusivity 0.37m 2/ hr (4ft 2/ hr) corresponding to copper.
Having listed two kinds of nip length commonly used in table 1, is unit with cm (inch), and 25.4cm (10in) is corresponding to the long nip press that adds of typical impulse dryer device, and 2.54cm (1 inch) is corresponding to the application of as shown in Figure 4 typical calender.Two kinds of web speed listing are unit with m/s (feet per minute).914 meters/minute (3,000 feet of per minutes) are the typical rate of current paper machine.30.48m/s (6,000 feet of per minutes) is roughly the upper range of the chart speed that industrial quarters now discusses.
As seen from Table 1, comprehensive thermal diffusivity, nip length and web speed, the radially maximum ga(u)ge roughly of outer surface housing 40 only needs about 0.51cm (2/10ths inches) thick, as shown in Table.In conjunction with Fig. 3, table 1 has also illustrated the double-decker of pressure roller 22.
Volume specific heat, promptly the thermal energy of unit volume is very approaching for interior very on a large scale metal haply, because low density metals has high specific heat usually, though high desnity metal specific heat is low, more material is arranged in the unit volume.Therefore, the volume that stands the material of cycle heating is whole good signs that add heat that roller 22 offers paper web in the process that roller 22 contact with 28 cycles of paper web.
Table 1
Thermal diffusivity Nip length Web speed Effective depth
m 2/hr ft 2/hr ??cm ???inch ??m/s ft/min ??cm ??inch
??0.065 ????0.7 ??25.4 ????10 ?15.24 ?3,000 ?0.218 ?0.086
??0.19 ????2 ??25.4 ????10 ?15.24 ?3,000 ?0.371 ?0.146
??0.28 ????3 ??25.4 ????10 ?15.24 ?3,000 ?0.455 ?0.179
??0.37 ????4 ??25.4 ????10 ?15.24 ?3,000 ?0.523 ?0.206
??0.065 ????0.7 ??2.54 ????1 ?15.24 ?3,000 ?0.069 ?0.027
??0.19 ????2 ??2.54 ????1 ?15.24 ?3,000 ?0.117 ?0.046
??0.28 ????3 ??2.54 ????1 ?15.24 ?3,000 ?0.152 ?0.060
??0.37 ????4 ??2.54 ????1 ?15.24 ?3,000 ?0.165 ?0.065
??0.065 ????0.7 ??25.4 ????10 ?30.48 ?6,000 ?0.155 ?0.061
??0.19 ????2 ??25.4 ????10 ?30.48 ?6,000 ?0.262 ?0.103
??0.28 ????3 ??25.4 ????10 ?30.48 ?6,000 ?0.320 ?0.126
??0.37 ????4 ??25.4 ????10 ?30.48 ?6,000 ?0.371 ?0.146
Should be understood that when seeing Fig. 3 that when effective depth shown in Figure 1 is double the degree of depth of the point corresponding with curve 75,78 and 82 also doubles.Therefore, be that a kind of steel alloy roller of 0.218cm (86/1000ths inches) is the copper of 0.525cm (207/1000ths inches) to effective depth from effective depth, mean that the material volume that surpasses twice is standing periodic temperature fluctuation.Thereby heat flow approximately exceeds one times in a specific circulation.
Can also find that from table 1 effective depth also reduces when nip length reduces.Therefore, as shown in Figure 4, in the calender of a nip 76 in 1.27-3.81cm (0.5-1.5 inch) scope, extremely thin high thermal conductive shell 87 is effective for increasing the heat conduction significantly.
Pressure roller 22 is by making with a cold mould centrifugal casting ferroalloy.Usually cause a roller with a cold metal housing centrifugal casting with high surface hardness and inner plasticity.The shell of high heat diffusivity material (for example copper or aluminium) the preferably surface by molten metal sprays and is sprayed on the outer surface 42.Typical metal spray coating technique comprises will adhere to surface on it to this surface sand-blasting to form a metal that is sprayed, heat the wire of one section required metal by electric arc or plasma, and with the metal jet of this heat fused to the surface 42 of Metal Substrate shell 38.Usually carry out the metal spraying operation while rotating basic shell 38, be coated with and be covered with continuous spray metal layer, up to reaching required thickness.Then roller is carried out Surface Finishing, the required surface smoothness of felt wrapped roll in the pressure roller of impulse dryer device or the calender is provided.
A kind of possible method that forms shell comprises that at first centrifugal casting one is thin outer, can then base steel shell 42 be cast on shell 40 by molten metal being sprayed in the chilled centrifugal mold.This method need prevent to form an oxide layer on shell 40, connects thereby can produce molecule between shell 40 and basic shell 34.
Other possible method is included on the surface 42 of its shell 38 carries out chemistry or electro-deposition.In chemical deposition, importantly to avoid the pore in institute's plated metal.Another kind of possible method, the extremely thin layer especially for for example calender can adopt vapour deposition.
Fig. 2 shows a kind of alternative impulse dryer device 120, and it has a pressure roller 122, and formation one adds long nip press 126 between the surface 134 of cambered surface profiled sheeting 124 and roller 122.Have a fluid-tight long nip press woollen blanket 130 that adds in the impulse dryer device 120.Cambered surface profiled sheeting 124 is a concave surface in the face of the one side of roller, and is mounted to and makes it press to roller 122.Nip 126 makes the paper web 128 that passes therethrough be subjected to a squeeze pressure in the time that prolongs.Nip woollen blanket 130 passes this nip between cambered surface profiled sheeting 124 and roller 122, incoming oil between cambered surface profiled sheeting and woollen blanket 130.This oil becomes between the profiled sheeting 124 woollen blanket 130 and arc to constitute the oil film wedge that surges.This oil film wedge transmits pressure to paper web, and lubricated simultaneously woollen blanket is by the motion of nip 126.One presses blanket 132 to pass nip 126 on paper web 128 times and woollen blanket 130.Paper web 128, press blanket 132 and woollen blanket 130 and roller 122 to be engaged with each other, with identical speed drive by frictional force.Therefore because paper web 128 and press the plane of blanket 132 and the face 134 of pressure roller 122 between do not have relative motion, paper web 128 is not subjected to significant shear action.Like this, paper web 128 mainly is being under pressure when adding long nip press 126.The effect of this pressure is that paper web is closely contacted with the surface 134 of pressure roller 122.
With a kind of and drier 20 similar methods, the pressure roller 122 in the impulse dryer device 120 has improved the efficient of common impulse dryer device.Roller 122 has a Metal Substrate shell 138 that is made of common steel alloy.Cover the shell 140 that one deck is made of a kind of material of high thermal diffusivity on this base shell 138.Shell 140 closely is engaged in the outer surface 142 of basic shell 138.Metal Substrate shell 138 has formed the support structure of shell 140.
Adopt common woollen blanket 130 and its to support 44.Woollen blanket 130 is a continuous ring.Width on its transverse machine is bigger than pressure roller 122, so the limit level (not shown) of woollen blanket exceeds the edge of paper web 128.One static beam 133 is under endless belt 130 and cambered surface profiled sheeting 124.This beam supports cambered surface profiled sheeting 124 by a hydraulic piston chamber 135 adjustablely, is provided with a piston 137 in the hydraulic piston chamber 135.Piston 137 fluid pressure in the chamber 135 below it is upwards pressed, and this chamber is a long trough, accepts piston slidably, and extends in cambered surface profiled sheeting 124 lower edge machine overall withs.Endless belt 130 is by last deflector roll 141 and 143, lower guide roll 145 and 149 and the device guiding that constitutes of draw roll 147.Draw roll 147 is installed to change the tension force in the woollen blanket 130 adjustablely.
Pressing blanket 132 to be bearing in an input roller 146 and presses on the blanket outlet roller 148.The diameter of typical pressure blanket input roller 146 and outlet roller 148 is 0.74m (2 feet), and corresponding pressure roller diameter is 1.59m (5 feet).The effect of roller 146,148 is the positions that infeed of dabbing blanket 132 being taken to the nip 126 that passes impulse dryer device 120.Press blanket 132 to be handled by a felt dryer (illustrating) after leaving outlet roller 148, felt dryer is discharged water and too much steam from woollen blanket 132, and woollen blanket just returns through input roller 146 and reuses then.
Pressure roller 122 is not shown among Fig. 2 adopts high controlling organization in the hydraulic pressure, but make pressure roller 122 to be shaped as mid diameter big, axially tapered.Using the shortcoming of crowned roll 122 is the pressure that can only form a kind of grade between roller 122 and cambered surface profiled sheeting 124.Therefore, the drying pressure in some if desired scopes, the middle height of then wishing a kind of work of employing.Schematically illustrated an induction heater 162 among Fig. 2.It has a coil 164 that passes to high frequency electric.Induction heater 162 essence are general type.It adopts the concussion magnetic field that is produced by the high frequency alternating current, forms vortex flow on the face 134 of roller 122.The induced-current heating that has a resistance in 134 on the surface makes it reach temperature required.
Fig. 4 shows and adopt the roller 86 with a high thermal diffusivity shell 87 in a calender 84.Calender is used for that paper web 82 is carried out lustrous surface and modifies.Fig. 4 illustrates a unit or " on the machine " calender 84.This calender comprises a calender unit that is made of felt wrapped roll 86,88,90 and 92.Calender has the hard nip between hard roller usually, a perhaps soft nip, and in soft nip hard roller 86,90 and be staggered by the soft roller 88,92 that elastic fibers constitutes, the structure of calender is a general type.Nip 94 length of the soft-nip calendering machine of bent type are 1.27～3.81cm (0.5-1.5 inch).Felt wrapped roll 86 can Infrared Heating, but also eddy-current heating.When adopting one to have the felt wrapped roll of shell 87 of a Metal Substrate shell 96 and a high thermal diffusivity, the heat between felt wrapped roll 86 and paper web 98 is conducted and is improved, thereby has increased the efficient of calender 84.As shown in table 1, owing to have short nip length, calender needs thin high diffusivity housing, is approximately 0.152cm (60/1000) inch.The radial thickness of the relative thin of shell makes the moulding of felt wrapped roll be more suitable for depositing in chemical films.The film of this relative thin also means the coating that can use nonmetallic high thermoconductivity, and for example diamond can apply felt wrapped roll, for example the vapor diamond deposition material.
Should be appreciated that along with web speed increases, the thickness of high thermal diffusivity shell reduces.
What should also be understood that top equation provides and the effective depth that illustrated provides in table 1 is the heat conducting maximum effective depth of roller material, adopts the degree of depth littler than maximum effective depth also can to increase the capacity of heat transmission of roller 22.
Should also be understood that above-mentioned nip length, roller diameter and roller temperature just illustrate, other temperature range, roller size and nip length also can be advantageously used in roller 22 of the present invention.
Should also be understood that the place that high supporting mechanism is illustrated and illustrates in, roller can have one mach in high face, in this, be deposited or molded the thin outer crust of a high thermal diffusivity on the high face.
Should also be understood that wherein copper and this class THERMAL DIFFUSIBILITY of aluminium are 0.28m 2/ hr (3ft 2/ hr) or higher, in some cases, the heat-obtaining diffusivity is 0.09m 2/ hr (1ft 2/ may be actual about hr).
Should be understood that specific structure and configuration of components that the present invention should not illustrated and describe limit here, present invention resides in the improved form of being done in the scope of its claims.

Claims (6)

1. one kind is used for the heated roller (22) that paper machine paper is handled, and comprises a basic shell (38) of being made by first material, and it constitutes the cylinder on an inside radius, an outer radius and the face of cylinder;
One shell of making by second material (40), its supporting also covers on the surface of described basic shell (38), and described shell (40) has an inside radius and outer radius, wherein, the difference of the inside and outside radius of described shell (40) is poor less than the inside and outside radius of described basic shell (38), it is characterized in that
Described first material is first metal of a high strength, low thermal diffusivity, make described basic shell (38) can supporting machinery load and
Described second material is second metal of selecting from aluminium and copper, and the thermal diffusivity of described second metal is higher than the thermal diffusivity of described first metal, improved to the heat transfer effect of the paper web (28) of described shell (40) engagement.
2. roller as claimed in claim 1 is characterized in that, described shell (40) fits tightly with the described face of cylinder of described basic shell (38);
One induction heater (62) is close to described shell (40) and is heated;
The radial thickness of described shell (40) is less than 0.51 centimetre (0.2 inch).
3. roller as claimed in claim 1 or 2 is characterized in that, described shell (40) is that described second metal is gone up the sprayed coating that forms at described basic shell (38).
4. roller as claimed in claim 1 is characterized in that, the difference of the inside and outside radius of described shell (40) is less than 0.762 centimetre (0.3 inch).
5. roller as claimed in claim 1 is characterized in that, described first metal is a steel alloy.
6. impulse dryer device that comprises the described roller of claim 1 (22), between described roller (22) and co-operating member (24), form a nip (26), to remove the liquid in the paper web (28), it is characterized in that described impulse dryer device satisfies following relational expression: X = 4 aL S
Here, X is the radial thickness of the shell (40) of described high thermal diffusivity, rice (foot)
S be described paper web (28) along the superficial velocity of a first direction by described nip (26), rice/hour (S foot/hour)
L is the length of described nip (26) along described first direction, rice (foot)
A is the thermal diffusivity of described shell (40),
Wherein, the surface of described roller (22) is heated during by described nip (26) when described paper web (28), and with the described paper web of heat transferred (28), the shell (40) of described roller (22) is made by second metal that thermal diffusivity is higher than 0.09 square metre/hour (1 square feet/hour).
CN94193754A 1993-10-13 1994-08-29 Impulse dryer roll with shell of high thermal diffusivity Expired - Fee Related CN1039929C (en)

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JPH08510803A (en) 1996-11-12
KR960705107A (en) 1996-10-09
FI961626A0 (en) 1996-04-12
EP0723612A1 (en) 1996-07-31
DE69412113T2 (en) 1999-03-25
DE69412113D1 (en) 1998-09-03
CA2173140A1 (en) 1995-04-20
JP2727135B2 (en) 1998-03-11
BR9407784A (en) 1997-03-18
CA2173140C (en) 2000-10-31
CN1133076A (en) 1996-10-09
PL175270B1 (en) 1998-12-31
EP0723612B1 (en) 1998-07-29
WO1995010659A1 (en) 1995-04-20
FI961626A (en) 1996-06-07

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