CN105297012A - Method for coating metal pipe with enamel and enamel coating equipment for achieving method - Google Patents
Method for coating metal pipe with enamel and enamel coating equipment for achieving method Download PDFInfo
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- CN105297012A CN105297012A CN201410274200.6A CN201410274200A CN105297012A CN 105297012 A CN105297012 A CN 105297012A CN 201410274200 A CN201410274200 A CN 201410274200A CN 105297012 A CN105297012 A CN 105297012A
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Abstract
The invention relates to a method for coating a metal pipe with enamel and enamel coating equipment for achieving the method. The method for coating the metal pipe with the enamel includes the steps that (a) the metal pipe is fed into a pre-treatment chamber, and therefore the surface of the metal pipe is pre-treated, wherein the metal pipe rotates while forward movement is done through a feeding conveying machine; (b) the metal pipe pre-treated in the step (a) is fed into a coating chamber, so that the surface of the metal pipe is coated with the enamel; and (c), the metal pipe coated in the step (b) is fed into a roasting chamber, so that the metal pipe is roasted. In the step (c), the roasting chamber comprises a roasting chamber conveyor with two or more sand-clock-shaped rollers, and the metal pipe is conveyed to an output conveyor while the bottom of the heated metal pipe is supported by the sand-clock-shaped rollers.
Description
Technical field
Present invention relates in general to a kind of is the metal tube coating method of enamel and the enamel coating equipment for the method.More specifically, present invention relates in general to a kind of is the finned tube coating method of enamel and the enamel coating equipment for the method, and finned tube has thermofin on the surface of metal tube.
Background technology
Because metal tube mainly uses in wet environment, on the surface of metal tube, therefore implement various coating method to improve weather resistance.As the one in coating method, the advantage of enamel coating method is, enamel has high heat resistance and highly-acidproof, but have problems because of the difficulty of coating procedure, such as, need roasting under high temperature (750 DEG C to 1000 DEG C), thus enamel coating method fails to be used widely.
Particularly, due to needs high-temperature calcination process, therefore need to provide large-scale roasting chamber to be long and the target coat enamel of large volume, make the economic inefficiencies of roasting process thus.Due to the problems referred to above, think may be long hardly and the target coat enamel of large volume.
Simultaneously, if metal tube uses in severe environment, such as be used as the finned tube of the heat exchanger of generator (because gas is cooled when using the gas containing acidic components to carry out heat exchange in generator, tube-surface and thermofin are exposed to acid dew point, thus low temperature corrosion is there is in finned tube) be coated with general application composition, then periodically the metal tube inevitably corroded should be replaced with new metal tube, not only cause inconvenience thus but also result in high cost.In order to solve this problem, the metal tube be made up of the material of such as stainless steel-based material or titanium can be used.But except unhelpful to basic solution, which results in cost increases and makes frequently to be replaced with by finned tube new.In addition, also proposed and a kind ofly polytetrafluorethylecoatings coatings is executed the method be applied on finned tube.But, polytetrafluoroethylmaterial material in thermotolerance be have circumscribed.Thus, expect enamel coating to execute on the metal tube being applied to and using in severe environment (such as, needing thermotolerance and acid proof environment).
The reason be difficult to for the surface-coated enamel of metal tube is as follows:
First, as mentioned above, high-temperature roasting room is needed.Particularly, when the length of metal tube is longer, need large-sized high-temperature roasting room, make thus to be more difficult to carry out enamel coating.
The second, when metal tube stands coating processes during high-temperature calcination process, metal tube can adversely bending or distortion in shape.About this point, the longer this problem of metal tube occurs more continually.Therefore, a kind of method preventing metal tube to be out of shape when metal tube is coated is needed.
3rd, because the oil component be retained in during preprocessing process on the surface of metal tube inhibits moisture enamel to be bonded to the surface of metal tube, therefore before carrying out enamel coating, oil component must be removed.But, use conventional pretreatment process to be difficult to effectively remove oil component.
That is, in preprocessing process, grit blast process is invalid for removal oil component.When introducing wet process, pre-treatment becomes complicated, thus causes coating efficiency to reduce.Therefore, be necessary that exploitation is a kind of easily by the method for oil component from the surface removal of metal tube.
4th, be difficult to after applying enamel, remove the bubble formed in the coating.Because the removal forming bubble in the coating determines coating quality, therefore the removal of bubble is extremely important in coating procedure.Particularly, when finned tube (see Figure 10) of heat exchanger (finned tube has multiple thermofin be formed on the surface of metal tube), be difficult to bubble removal from the surface of metal tube and the surface of each thermofin.But such bubble should thoroughly be removed to obtain the finned tube with high-durability.In the past, employ and knock the method that metal tube removes bubble.But, when long metal pipe, be difficult to make in this way and the poor effect of the method.
Therefore, in order to enamel coating being executed the excellent physical properties being applied to and metal tube also then utilizing enamel coating, should solve the problem in advance.
Summary of the invention
Therefore, consider and appear at the problems referred to above of the prior art and made the present invention, and the object of this invention is to provide a kind of enamel coating method and enamel coating equipment, it can prevent the bending and distortion during high-temperature calcination process of long metal tube.
Another object of the present invention is to provide a kind of enamel coating method and enamel coating equipment, and except realizing simple equipment, it can also simplify the process of metallizing pipe.
To achieve these goals, the invention provides a kind of method for metal tube coating enamel, described method comprises: described metal tube is sent in pretreatment chamber by (a), carry out pre-treatment to the surface of described metal tube thus, wherein said metal tube is rotated while moving forward by feeding conveyor; B () will be sent in coating chamber through pretreated described metal tube in (a), be the surface-coated enamel of described metal tube thus, described enamel is provided by the enamel supplying-nozzle be arranged in described coating chamber; And (c) will be sent in roasting chamber through the described metal tube of coating in (b), at the temperature of 750 DEG C to 1000 DEG C, roasting is carried out to described metal tube thus, wherein, in (c), described roasting chamber comprises roasting chamber's transfer roller with two or more hourglass shape rollers, and described metal tube is transported to output transfer roller by described roasting chamber transfer roller while the bottom of the metal tube heated described in described hourglass shape roll support.
In addition, the invention provides a kind of equipment for metal tube coating enamel, described equipment has coating unit, and described coating unit comprises: pretreatment chamber, and pre-treatment is carried out on the surface that described pretreatment chamber is configured to sending into the metal tube also rotated from feeding conveyor simultaneously; Coating chamber, described coating chamber is configured to: when being sent in described coating chamber through pretreated described metal tube, and be the surface-coated enamel of described metal tube, described enamel is provided by the enamel supplying-nozzle be arranged in described coating chamber; And roasting chamber, described roasting chamber is configured to: when the described metal tube through coating is sent in described roasting chamber, metal tube described in the roasting temperatures of 750 DEG C to 1000 DEG C, wherein, described roasting chamber comprises roasting chamber's transfer roller, and described roasting chamber transfer mechanism causes, while the bottom of the metal tube heated described in supporting, described metal tube is transported to output transfer roller, and described roasting chamber transfer roller comprises two or more hourglass shape rollers.
As obvious in the foregoing description, the advantage of enamel coating method of the present invention is, which prevent recurrent bending or distortion in long metal tube during high-temperature calcination process, thus provides the metal tube of the enamel coating with excellent quality.
The advantage of enamel coating method of the present invention is, it makes use of roasting chamber's transfer roller, thus (this is different from ordinary method can to carry out roasting process when not being connected to each other by metal tube, in ordinary method, before metal tube is fed to pretreatment chamber, the rearward end of this metal tube is connected to another metal tube, and roasting process carries out in the attached state), thereby simplify coating procedure and improve the productivity of the metal tube of enamel coating.
In addition, the advantage of enamel coating method of the present invention is, hourglass shape roller replaces a pair rotational roller, thus achieves the simplification of coating equipment.
Accompanying drawing explanation
By the detailed description of carrying out below in conjunction with accompanying drawing, above-mentioned and other objects, features and advantages of the present invention will be better understood, in the accompanying drawings:
Fig. 1 is the view of the example of the enamel coating equipment shown for enamel coating method of the present invention;
Fig. 2 A and Fig. 2 B shows the enamel coating equipment for enamel coating method of the present invention, and wherein, Fig. 2 A shows feeding conveyor and Fig. 2 B shows the structure being included in motor in feeding conveyor and roller;
Fig. 3 is the schematic sectional view of the coating unit of the enamel coating equipment shown for enamel coating method of the present invention;
Fig. 4 is the view of the structure schematically showing the induction heater used in enamel coating method of the present invention;
The photo of Fig. 5 captured by the manufacturing processed to the induction heater used in enamel coating method of the present invention;
Fig. 6 is the photo of the metal tube heated by the induction heater used in enamel coating method of the present invention;
Fig. 7 schematically shows the view be included in for the coating chamber (common tube coating) in the coating unit of the enamel coating equipment of enamel coating method of the present invention;
Fig. 8 schematically shows the view be included in for the coating chamber (finned tube coating) in the coating unit of the enamel coating equipment of enamel coating method of the present invention;
Fig. 9 is the view in the air spray direction schematically showing the air injection nozzle used in enamel coating method of the present invention;
Figure 10 A to Figure 10 C is the photo taken the finned tube applied by enamel coating method of the present invention;
Figure 11 is the view schematically showing enamel coating equipment, and wherein enamel coating equipment adopts the hourglass shape roller used in enamel coating method of the present invention;
Figure 12 is the view of pretreatment chamber's transfer roller 400 of the enamel coating equipment schematically shown for enamel coating method of the present invention, coating chamber transfer roller 500 and roasting chamber's transfer roller 600;
Figure 13 is the skeleton view showing the hourglass shape roller used in enamel coating equipment of the present invention;
Figure 14 is the skeleton view showing the hourglass shape roller with cooling solution circulating path 271, and this hourglass shape roller uses in enamel coating equipment of the present invention.
Embodiment
Should carry out reference to accompanying drawing now, use identical Reference numeral to represent same or similar parts in all of the figs.
Hereinafter, the preferred embodiments of the present invention are described in detail with reference to accompanying drawing.In the following description, if judged to make theme of the present invention unclear to the detailed description of the relevant known function of the present invention or structure, then this detailed description has been saved.
As shown in Fig. 1 to Figure 14, enamel coating method of the present invention comprises: metal tube 10 is sent in pretreatment chamber 110 by (a), carry out pre-treatment to the surface of metal tube 10 thus, described metal tube 10 is rotated while moving forward by feeding conveyor 200; B pretreated in (a) metal tube 10 is sent in coating chamber 120 by (), be the surface-coated enamel of metal tube 10 thus, described enamel is provided by the enamel supplying-nozzle 121 be arranged in coating chamber 120; And (c) by being sent in roasting chamber 130 through the metal tube 10 of coating in (b), carries out roasting thus at the temperature of 750 DEG C to 1000 DEG C to metal tube 10.
In (c), roasting chamber 130 comprises roasting chamber's transfer roller 600 with two or more hourglass shape rollers 270.Roasting chamber's transfer roller 600 is configured to be transported to by metal tube 10 while hourglass shape roller 270 supports the bottom of the metal tube 10 heated and exports transfer roller 300.
In enamel coating method of the present invention, each hourglass shape roller 270 can be arranged on and become on the axle of the clockwise or counterclockwise angle of 5 ° to 35 ° relative to the x wire vertical with the longitudinal wire of roasting chamber's transfer roller 600.In this case, roasting chamber's transfer roller 600 can be configured to while hourglass shape roller 270 supports the bottom of the metal tube 10 heated by making metal tube 10 rotate and moving forward and metal tube 10 is transported to output transfer roller 300.
Enamel coating method of the present invention has following characteristics: as shown in figure 12, roasting chamber 130 is provided with roasting chamber's transfer roller 600 with two or more hourglass shape rollers 270, and roasting chamber's transfer roller 600 is formed to be transported to by metal tube 10 while hourglass shape roller 270 supports the bottom of the metal tube 10 heated and exports transfer roller 300.
That is, in (c), the process of calcined metal pipe is carried out under the high temperature of 750 DEG C to 1000 DEG C.Thus, if metal tube 10 is connected to each other and the leading section of each metal tube 10 and rearward end are not supported thus, then the part do not supported when metal tube 10 is through roasting chamber 130 can bend or distortion.Therefore, according to prior art, before metal tube 10 is fed to pretreatment chamber 110, the rearward end of this metal tube 10 is connected to another metal tube 10.In this state, preprocessing process, coating procedure and roasting process is carried out.
But, if the rearward end of metal tube 10 is connected to the leading section of another metal tube 10, then need the work of paying this operation.In addition, even if when metal tube 10 is connected to each other and is supported, as individual each metal tube 10 is heated with the high temperature of 750 DEG C to 1000 DEG C in roast room 130, metal tube 10 also can bend or distortion usually.Thus, the present invention is proposed in order to solve the problem.
As shown in figure 12, in order to more desirably prevent metal tube 10 bending or distortion in roasting process, enamel coating method of the present invention comprises support and roasting chamber's transfer roller 600 of moving metal pipe 10 further, supports the hot metal pipe 10 through roasting chamber 130 thus and prevents metal tube 10 to be out of shape thus.
As shown in figure 12, roasting chamber's transfer roller 600 can be configured to comprise two or more hourglass shape rollers 270.Each hourglass shape roller 270 is installed in and becomes on the axle of the angle of clockwise or counterclockwise 5 ° to 35 ° (being more preferably 10 ° to 30 °) relative to the x wire vertical with the longitudinal wire of roasting chamber's transfer roller 600.
As shown in Figure 13 and Figure 14, hourglass shape roller 270 has the shape similar with the shape of hourglass.When on the axle that such hourglass shape roller 270 is installed in the angle of 5 ° to 30 ° becoming clockwise or counterclockwise relative to the x wire vertical with the longitudinal wire of transfer roller and by the dynamic rotation that directly or indirectly provides, hourglass shape roller 270 can realize rotating and advance the function of the metal tube 10 be shelved on this roller 270.In this, the angle that tilts of the axle of hourglass shape roller 270 is for determining the speed of rotation of metal tube 20.In enamel coating method of the present invention, the speed of rotation of metal tube is such as 2 to 10 per minutes, is preferably 5 to 9 per minutes.For rotations per minute, the angle that the axle of hourglass shape roller 270 tilts can be regulated.
Except hourglass shape roller 270, the structure of roasting chamber's transfer roller 600 can adopt usual used structure in the art.Transmission of power can be undertaken by normally used method in the art to hourglass shape roller 270.
Hourglass shape roller 270 can be made up of any material, as long as this material can bear the temperature of 750 DEG C to 1000 DEG C.Preferably can use metallic substance.
As mentioned above, when providing roasting chamber's transfer roller 600 in roasting chamber 130, even if metal tube 10 is not connected to each other, in roasting process, also can not there is the bending of metal tube or distortion, and identical effect can be realized equally when metal tube 10 is connected to each other.
Metal tube 10 can come automatically or to be manually connected to each other by using the known various transoms of persons skilled in the art.
Because the process of calcined metal pipe 10 is at high temperature carried out, the roasting chamber's transfer roller 600 be therefore arranged in roasting chamber 130 also should have excellent heat resistance.Specifically, hourglass shape roller 270 directly contacts with the metal tube at high temperature heated, thus hourglass shape roller 270 should have thermotolerance.But because to have the heat-resisting material being enough to the high temperature bearing 750 DEG C to 1000 DEG C be rare and costliness, therefore enamel coating method of the present invention is intended to be cooled hourglass shape roller 270 by cooling solution.
That is, in enamel coating method of the present invention, as shown in figure 14, the hourglass shape roller 270 be included in roasting chamber's transfer roller 600 can be provided through the cooling solution circulating path 271 of turning axle.If the cooling solution of such as refrigerant is circulated, even if hourglass shape roller 270 (namely 750 DEG C to 1000 DEG C) under the maturing temperature of metal tube 10 also reliably can run and can not produce any problem by the cooling solution circulating path 271 formed in the above described manner.
As being shown specifically in Fig. 1 and Fig. 2, in enamel coating method of the present invention, continuous rotation and the propelling of metal tube 10 can be realized by motor 220 and some right rotational roller 230, motor 220 is arranged in feeding conveyor 200 and/or outfeed belt conveyor 300, and described some right rotational roller 230 form stagger angle and rotate with the power by being provided by motor 220 and advance metal tube.
In addition, as is illustrated by figs. 11 and 12, continuous rotation and the propelling of metal tube 10 can be undertaken by motor (not shown) and hourglass shape roller 270, described motor is arranged in feeding conveyor 200 and/or outfeed belt conveyor 300, and the power that hourglass shape roller 270 is configured by be provided by described motor rotates and advances metal tube.
As is illustrated by figs. 11 and 12, each hourglass shape roller 270 is installed in and becomes on the axle of the angle of clockwise or counterclockwise 5 ° to 35 ° (more preferably 10 ° to 30 °) relative to the x wire vertical with the longitudinal wire of transfer roller.As shown in Figure 13 and Figure 14, hourglass shape roller 270 has the shape similar with the shape of hourglass.When on the axle that such hourglass shape roller 270 is installed in the angle of 5 ° to 30 ° becoming clockwise or counterclockwise relative to the x wire vertical with the longitudinal wire of transfer roller and by the dynamic rotation that directly or indirectly provides, hourglass shape roller 270 can realize the function rotating and advance the metal tube 10 be shelved on this roller 270.In this, the angle that tilts of the axle of hourglass shape roller 270 is for determining the speed of rotation of metal tube 20.
If use above-mentioned hourglass shape roller 270 in transfer roller, then roller is simplified, thus causes the simplification of whole equipment.
In enamel coating method of the present invention, the speed of rotation of metal tube is such as 2 to 10 per minutes, is preferably 5 to 9 per minutes.Can by regulating the stagger angle of rotational roller 230 (see Fig. 2 B) or the speed of rotation by regulating the angle of the axle of hourglass shape roller 270 (see Figure 11) inclination to control metal tube.
As shown in Fig. 1 and Fig. 2 A and Fig. 2 B, in enamel coating method of the present invention, if use feeding conveyor 200 and outfeed belt conveyor 300 and preprocessing process, coating procedure and roasting process before metal tube is fed to pretreatment chamber 110, make the rearward end of this metal tube 10 be connected to another metal tube 10 state under carry out, then can not need independent pretreatment chamber's transfer roller 400 and independent coating chamber transfer roller 500.That is, as in the present invention, if comprising pretreatment chamber 110, coating chamber 120 and the coating unit 100 of roasting chamber 130 is that the length of compact thus coating unit 100 is very short compared with the length of metal tube to be coated, even if then pretreatment chamber 110 and coating chamber 120 do not use independent transfer roller, the continuous rotation of metal tube 10 and advance also can by being arranged in feeding conveyor 200 before and after pretreatment chamber 110 and coating chamber 120 and outfeed belt conveyor 300 realizes.
Simultaneously, if each metal tube 10 is applied individually, instead of carry out preprocessing process, coating procedure and roasting process under the state making the rearward end of this metal tube 10 be connected to another metal tube 10 before metal tube 10 is fed to pretreatment chamber 110, then can need one or more pretreatment chamber's transfer roller 400, coating chamber transfer roller 500 and roasting chamber's transfer roller 600, to make corresponding metal tube 10, there is in preprocessing process, coating procedure and roasting process rotation and propulsive force.
The preprocessing process of the metal tube in step (a) place can by such as grit blast process, sandblasting and shot peening etc. in the art widely used method carry out.
In addition, metal tube can carry out pre-treatment by wet type pre-treatment normally used in metal treatment.Can adopt between wet type pre-treatment period and produce hyperacoustic method in preprocessing solution, thus more effectively from the surface removal impurity of metal tube.
But oil component successfully cannot be removed by grit blast process, and make the increasing number of the parts installed when introducing wet processed and preprocessing process is complicated, thus coating efficiency is lowered.Thus, the automatic enamel coating method be applied to by aforesaid method in the present invention is difficult to.
Therefore, enamel coating method of the present invention can be adopted with the following method: heating unit 111 is applied to pretreatment chamber 110 with at high temperature heating metal pipe 10, make oil component burn thus and within comparatively short time interval by oil component from surface removal.
High-temperature heating process can be undertaken by using conventional heating unit 111.That is, the example of heating unit can comprise electric furnace, plasma furnace, heavy oil stove, light oil stove, gas furnace, hydrogen process furnace and induction heater.
In enamel coating method of the present invention, preferably, induction heater 111 can be used as the induction heater shown in Fig. 4 and Fig. 5.In induction heater, preferably can adopt the high frequency induction heater using high-frequency current.
In the enamel coating method of the present invention, the carrying out due to the charging of metal tube 10 combines and rotates, and therefore induction heater 111 can have any shape.That is, due to no matter the shape of induction heater 111 how, metal tube 10 can both be uniformly heated, and therefore all shapes as known in the art are all fine.
As shown in Figures 3 to 5, induction heater 111 preferably can use the induction heater of round shape or arc (not shown), and it has the radius-of-curvature being greater than the external diameter of metal tube 10 of 5mm to 150mm.Induction heater can be arranged along the travel direction of metal tube 10 as follows: namely, makes to maintain predetermined distance between the outside surface of the metal tube 10 of movement and the inner curved surfaces of round shape induction heater.
High-temperature heat treatment is preferably carried out 10 seconds to 4 minutes (more preferably carrying out 10 seconds to 2 minutes) in preprocessing process at the temperature of 300 DEG C to 600 DEG C (more preferably 400 DEG C to 500 DEG C).If high-temperature heat treatment is carried out at lower than the temperature of 300 DEG C, then need to take a long time and remove oil component.On the contrary, if high-temperature heat treatment is carried out at higher than the temperature of 500 DEG C, then economical efficiency is lowered.In addition, if high-temperature heat treatment carries out the time period being less than 10 seconds, be then difficult to reach required high temperature.On the contrary, if high-temperature heat treatment is carried out 5 minutes or the longer time period, then the reduction of productivity can be caused.The metal tube completing high-temperature heat treatment in preprocessing process is cooled to be sent in coating chamber under 60 DEG C or lower temperature.
When using induction heater 111 to carry out high-temperature heat treatment, can heat metal tube 10 in about one minute with thermal treatment temp (namely 300 DEG C to 600 DEG C), thus be easy to the compactedness realizing pretreatment chamber 110, and significantly reduce pre-treatment cost.
In addition, compared with conventional heating device, induction heater 111 can be easily manufactured into small size to match with the metal tube 10 with minor diameter, and in addition, heating operation can be carried out in the distance near metal tube 10, thus make efficiency fabulous.
As shown in Figure 4, induction heater 111 can comprise: be formed the heater coil 112 of circular pipe shape and be configured to supply to heater coil 112 AC power 114 (see Fig. 5) of electric current.Jacket 113 can be arranged on the outside of heater coil 112 alternatively.
As shown in Figure 4, if metal tube 10 to be inserted in the circular pipe formed by heater coil 112 and to supply alternating current, then on the surface of metal tube 10, produce resistance due to eddy current, thus produce heat on the surface of metal tube 10.
Fig. 5 is the image of taking pictures of the manufacturing processed of induction heater 111.As shown in Figure 5, induction heater 111 is configured so that heater coil 112 is formed as circular pipe shape, and then is supplied to alternating-current.
Fig. 6 is the photo taken metal tube 10, and this metal tube 10 is heated by the induction heater 111 of the process manufacture by Fig. 5.Can see that whole pipe is heated to red heat state from Fig. 6.
According to the test of Fig. 5 and Fig. 6, from heating operation after 18 seconds, the surface temperature of metal tube 10 reaches 400 DEG C.After 56 seconds, surface temperature reaches 680 DEG C.Therefore, induction heater 111 can make the High Temperature Pre process of metal tube 10 complete in about one minute.
In step (b), the coating procedure of metal tube is according to carrying out with under type of illustrating in figures 7 and 8: move forward and the metal tube 10 simultaneously rotated is fed in coating chamber 120, make the surface of metal tube 10 coated by the enamel that provided by the enamel supplying-nozzle 121 be arranged in coating chamber, or except the method, the coating brush 122 also making to be arranged on enamel supplying-nozzle 121 rear with move forward and the surface contact of the metal tube 10 simultaneously rotated, so that remove execute the surface being applied to metal tube 10 excessive enamel and simultaneously by bubble from coating removal.
In addition, air jet system 123 is arranged on the rear of enamel supplying-nozzle 121, thus air is ejected into the speed of 0.05m/s to 3m/s (more preferably 0.1m/s to 1.5m/s) and moves forward and on the surface of the metal tube 10 rotated by this air jet system 123 simultaneously, thus from the excessive enamel of the surface removal of metal tube 10 and simultaneously by bubble from coating removal.
If air injection rate is less than 0.05m/s, be then difficult to obtain air spray effect.On the other hand, if air injection rate is greater than 3m/s, then executed deposited enamel can exceedingly be removed.
When air spray process is undertaken by enamel supplying-nozzle 121 by this way, can easily by the surface removal of excessive enamel from metal tube, can effectively by bubble from coating removal, and substantially become dry in the step of the enamel executing the surface being applied to metal tube before roasting process, thus prevent enamel from solidifying while falling along gravity direction in roasting process, thus prevent and form rough coated surface.
In addition, effectively by the surface removal of bubble from metal tube in enamel coating procedure, thus evenly and firmly coating can be formed.Especially, when the metal tube (such as, metal fin pipe) with unfairness surface is coated, it is very easy for removing the bubble be formed in each part, and this bubble is not easy to be removed by existing method.
The air ejected from air injection nozzle 123 can be more preferably the warm air of 30 DEG C to 200 DEG C.When jets of heated air by this way, more effectively can remove bubble, and the enamel be coated on metal tube 10 more effectively can become dry before it enters roasting chamber 13.
In addition, air injection nozzle 123 can be arranged on the rear of the coating brush 122 being positioned enamel supplying-nozzle 121 rear.In this case, enamel can be executed equably the surface being applied to metal tube, and more desirably can remove bubble.
As shown in Figure 7, the enamel supplying-nozzle 121 of desired number can be arranged on the top of the metal tube 10 be admitted to along the working direction of metal tube 10.But this is only an exemplary embodiment, and various enamel supplying-nozzle 121 can be mounted freely on each position.If enamel flows out from each enamel supplying-nozzle 121 installed by this way or ejects, then enamel is executed equably to be applied to and is moved forward and the metal tube 11 simultaneously rotated.
As long as coating brush 122 is positioned at enamel supplying-nozzle 121 rear when observing along the working direction of metal tube 10, then it is unrestricted for applying brush 122 position of installing.In addition, to remove and by bubble from coating removal, then the coating brush of any shape is all feasible as long as coating brush can execute the excessive enamel be applied on metal tube 10.If metal tube 10 is the finned tube 10 in its surface with thermofin 12, then coating brush should be made up of the regenerated fiber with applicable intensity and fineness, is uniformly coated in each part of thermofin 12 to enable enamel.
As long as air injection nozzle 123 is positioned at the rear of enamel supplying-nozzle 121 when observing along the working direction of metal tube 10, then the position that air injection nozzle 123 is installed is unrestricted.In addition, as long as nozzle can be removed the excessive enamel executing and be applied on metal tube 10 and in addition can from coating removal bubble, then the nozzle of any shape is all feasible.
Especially, as shown in Figure 9, air injection nozzle 123 preferably sprays air from the side of metal tube 10 along the direction contrary with the sense of rotation of metal tube 10.In addition, air injection nozzle 123 is preferably mounted to enable sprayed air arrive metal tube 10 bottom.
Like this, when sprayed air arrive move forward and the metal tube 10 simultaneously rotated bottom time, execute be applied to metal tube 10 surface on excessive enamel can easily concentrate on the bottom of metal tube 10 by the air sprayed, and easily can fall under gravity, guarantee thus easily to remove excessive enamel.In addition, compared to the air spray along the direction identical with the sense of rotation of metal tube 10, the air spray along the direction contrary with the sense of rotation of metal tube 10 more effectively can realize above-mentioned purpose.
Because enamel coating method of the present invention has the coating brush 122 and/or air injection nozzle 123 constructed in a manner described, even if therefore when the metal tube with complicated surface shape is coated, such as have on the surface of metal tube the finned tube 10 (see Figure 10 A to Figure 10 C) for heat exchanger of thermofin 12 coated time, also can provide fabulous effect.
In (c), the high-temperature calcination process of metal tube carries out under 750 DEG C to 1000 DEG C (more preferably 750 DEG C to 870 DEG C).Thus, roasting chamber 130 is provided with heating unit.Described heating unit can use any conventional heating unit used in the art, and the example of heating unit can comprise electric furnace, plasma furnace, heavy oil stove, light oil stove, gas furnace, hydrogen process furnace and induction heater.
In the present invention, induction heater preferably can be used as heating unit.Induction heater preferably can use induction heater 131 as shown in Figure 3.Compared with the heating unit of routine, induction heater 111 can be easily manufactured into reduced size to match with the metal tube 10 with small diameter, and in addition, heating operation can be carried out in the distance near metal tube 10, thus make efficiency fabulous.
Especially, because metal tube 10 is heated by induction heating method, heat only produces on the surface of the metal tube 10 as conductor.Thus, first metal tube is heated, and then executes the enamel be applied on the surface of metal tube and is heated by above-mentioned heat, thus enamel is evenly and join to more firmly on the surface of metal tube 10.In addition, defective coating is minimized.
On the contrary, when using conventional heating device, heat is transmitted to metal tube 10 by the enamel executed in the profile being applied to metal tube 10.Therefore, first enamel heated before metal tube 10 is by heating, thus enamel can flow down along gravity direction and probably defective coating can occur thus, and in addition, the steadiness of coating is lower than induction heating method.
In enamel coating method of the present invention, metal tube 10 is fed in the room be associated while rotation, thus the shape of induction heater 131 is unimportant.That is, no matter the shape of induction heater 131 how, metal tube 10 can be uniformly heated, and therefore induction heater 131 can have any shape as known in the art.
As shown in Figures 3 to 5, induction heater 131 preferably can use the induction heater of round shape or arc (not shown), and it has the radius-of-curvature being greater than the external diameter of metal tube 10 of 5mm to 150mm.Induction heater can be arranged along the travel direction of metal tube 10 as follows: namely, makes to keep predetermined distance between the outside surface of the metal tube 10 of movement and the inner curved surfaces of round shape induction heater.
Induction heater 131 can comprise the heater coil 132 being formed as circular pipe shape and the AC power 134 (see Fig. 5) being configured to supply to heater coil 132 electric current.Jacket 133 can be arranged on the outside of heater coil 132 alternatively.
As shown in Figure 4, if metal tube 10 to be inserted in the circular pipe formed by heater coil 132 and to supply alternating current, then on the surface of metal tube 10, produce resistance due to eddy current, thus produce heat on the surface of metal tube 10.
Fig. 5 is the image of taking pictures of the manufacturing processed of induction heater 111.As shown in Figure 5, induction heater 131 is configured so that heater coil 132 is formed as circular pipe shape, and then is supplied to alternating-current.
Fig. 6 is the photo taken metal tube 10, and this metal tube 10 is heated by the induction heater 131 of the process manufacture by Fig. 5.Can see that whole pipe is heated to red heat state from Fig. 6.
According to the test of Fig. 5 and Fig. 6, from heating operation 1 point after 11 seconds, the surface temperature of metal tube 10 reaches 800 DEG C.Therefore, induction heater 131 can make the roasting of metal tube 10 complete in about 2 minutes.
In enamel coating method of the present invention, induction heater 131 preferably can adopt the high frequency induction heater using high-frequency current.
Enamel is coated with in order to make metal tube, with regard to prior art, metal tube can be placed in roasting chamber wherein by needs, but with regard to enamel coating equipment of the present invention, even if longer metal tube also can be easily applicable enamel in the coating unit comprising compact roasting chamber.Thus, the advantage of enamel coating method of the present invention is, when metal tube has the length of 5m or longer, it is more more economical than prior art.Such as, suppose that the finned tube of the heat exchanger used in generator has the length of 18m, according to conventional methods, need the roasting chamber in the space with 18m or longer to carry out coating procedure, therefore it is uneconomic in efficiency and space availability ratio, but, according to the present invention, can (its entire length is about 4m or shorter) easily and carry out roasting process economically in compact roasting chamber.
In addition, as shown in Fig. 1 to Figure 14, the present invention relates to a kind of for the equipment for metal tube coating enamel.
Enamel coating equipment of the present invention comprises coating unit 100.Coating unit 100 comprises: pretreatment chamber 110, and pretreatment chamber 110 is configured to send into feeding conveyor 200 and pre-treatment is carried out on the surface of the metal tube 10 simultaneously rotated; Coating chamber 120, coating chamber 120 is configured to: when being sent in coating chamber through pretreated metal tube 10, and be the surface-coated enamel of metal tube 10, described enamel is provided by the enamel supplying-nozzle 121 be arranged in coating chamber 120; And roasting chamber 130, roasting chamber 130 is configured to: when the metal tube through coating is sent in roasting chamber, at the roasting temperature metal tube of 750 DEG C to 1000 DEG C.
Roasting chamber 130 comprises roasting chamber's transfer roller 600, and described roasting chamber transfer roller 600 is configured to be transported to by metal tube while supporting the bottom by heating metal pipe 10 export transfer roller 300.Roasting chamber's transfer roller 600 comprises two or more hourglass shape rollers 270.
Because all technical characteristics of enamel coating method can be applied to enamel coating equipment, therefore the identical description of described feature will be saved herein.
The hourglass shape roller be included in roasting chamber's transfer roller can be arranged on and become on the axle of the clockwise or counterclockwise angle of 5 ° to 35 ° relative to the x wire vertical with the longitudinal wire of roasting chamber's transfer roller.
Coating unit 100 is preferably 5m or shorter along the entire length of the feedstock direction of metal tube.
In enamel coating equipment, the pretreatment chamber 110 of coating unit 100 is 3m or shorter along the entire length of the feedstock direction of metal tube 10, is preferably 1m or shorter; And the entire length of coating chamber 120 is 2m or shorter, be preferably 1m or shorter; And the entire length of roasting chamber 130 is 7m or shorter, be preferably 5m or shorter.This achieves the compactedness of coating unit 100 better.
Enamel coating equipment of the present invention may further include feeding conveyor 200 and outfeed belt conveyor 300, feeding conveyor 200 is configured to rotate and advance metal tube 10, be sent in pretreatment chamber 110 by metal tube 10 thus, outfeed belt conveyor 300 is configured to the metal tube through coating to pull out from roasting chamber.
As shown in Figure 2 A, feeding conveyor 200 comprises metal tube and to bank up part 240, metal tube loading station 250 and metal tube transfer part 260, and metal tube transfer part 260 is configured to metal tube to transfer to loading station from part of banking up.Some metal tubes are transferred to loading station 250 from part 240 of banking up with predetermined time interval by metal tube transfer part 260, thus make metal tube 10 can be continuously provided to coating unit 100.
Such structure can be applied to outfeed belt conveyor 300 equally.In outfeed belt conveyor 300, be transferred to metal tube through the metal tube 11 of coating from metal tube loading station 250 and bank up part 240.
Although disclose the preferred embodiments of the present invention for exemplary object, but it will be understood by those skilled in the art that, when not departing from scope and spirit of the present invention disclosed in claims, various remodeling, interpolation and replacement are all possible.
Claims (10)
1., for the method for metal tube coating enamel, comprising:
A described metal tube is sent in pretreatment chamber by (), carry out pre-treatment thus to the surface of described metal tube, and wherein said metal tube is rotated while moving forward by feeding conveyor;
B () will be sent in coating chamber through pretreated described metal tube in (a), be the surface-coated enamel of described metal tube thus, described enamel is provided by the enamel supplying-nozzle be arranged in described coating chamber; And
C (), by being sent in roasting chamber through the described metal tube of coating in (b), carries out roasting to described metal tube thus at the temperature of 750 DEG C to 1000 DEG C,
Wherein, in (c), described roasting chamber comprises roasting chamber's transfer roller with two or more hourglass shape rollers, and each described hourglass shape roller is installed in and becomes on the axle of the clockwise or counterclockwise angle of 5 ° to 35 ° relative to the x wire vertical with the longitudinal wire of described roasting chamber transfer roller, and described roasting chamber transfer mechanism causes: by making described metal tube rotate and move forward and described metal tube is transported to output transfer roller while the bottom of the metal tube heated described in described hourglass shape roll support.
2. method according to claim 1, wherein, described hourglass shape roller comprises the cooling solution circulating path through turning axle, and (c) comprises further cooling solution is circulated by described cooling solution circulating path.
3. method according to claim 1, wherein, in (b), further air jet system is installed at the rear of described enamel supplying-nozzle, so as described air jet system with the speed of 0.05m/s to 3m/s by air spray on the surface of described metal tube.
4. method according to claim 3, wherein, the air sprayed from described air injection nozzle is the warm air of 30 DEG C to 200 DEG C.
5. method according to claim 3, wherein, described air injection nozzle sprays air from the side of described metal tube along the direction contrary with the sense of rotation of described metal tube, and enables sprayed air arrive described metal tube bottom.
6. method according to claim 3, wherein, in (a), described pretreatment chamber is provided with heating unit, and the high-temperature heat treatment of described metal tube carries out being used as preprocessing process in 10 seconds to 4 minutes at the temperature of 300 DEG C to 600 DEG C.
7. method according to claim 6, wherein, in (c), described roasting chamber is provided with the induction heater as heating unit.
8. method according to claim 7, wherein, described induction heater is the induction heater of round shape or arc, described induction heater has the radius-of-curvature being greater than the external diameter of described metal tube of 5mm to 150mm, and described induction heater is arranged along the travel direction of metal tube as follows: make to keep predetermined distance between the inner curved surfaces of the outside surface of the metal tube of movement and described round shape induction heater.
9. method according to claim 1, wherein, described metal tube is the finned tube for heat exchanger, and described finned tube has the thermofin on the surface being formed in described metal tube.
10. for the equipment for metal tube coating enamel, described equipment has coating unit, and described coating unit comprises: pretreatment chamber, and pre-treatment is carried out on the surface that described pretreatment chamber is configured to sending into the metal tube also rotated from feeding conveyor simultaneously; Coating chamber, described coating chamber is configured to: when being sent in described coating chamber through pretreated described metal tube, and be the surface-coated enamel of described metal tube, described enamel is provided by the enamel supplying-nozzle be arranged in described coating chamber; And roasting chamber, described roasting chamber is configured to: when the described metal tube through coating is sent in described roasting chamber, metal tube described in the roasting temperatures of 750 DEG C to 1000 DEG C,
Wherein, described roasting chamber comprises roasting chamber's transfer roller with two or more hourglass shape rollers, and each described hourglass shape roller is installed in and becomes on the axle of the clockwise or counterclockwise angle of 5 ° to 35 ° relative to the x wire vertical with the longitudinal wire of described roasting chamber transfer roller, and described roasting chamber transfer mechanism causes while the bottom of the metal tube heated described in described hourglass shape roll support by making described metal tube rotate and move forward and described metal tube is transported to output transfer roller.
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| CN201410274200.6A CN105297012A (en) | 2014-06-18 | 2014-06-18 | Method for coating metal pipe with enamel and enamel coating equipment for achieving method |
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| CN201410274200.6A CN105297012A (en) | 2014-06-18 | 2014-06-18 | Method for coating metal pipe with enamel and enamel coating equipment for achieving method |
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Application publication date: 20160203 |