CN1218162A

CN1218162A - Manufacture of steel pipe with polyethylene coating

Info

Publication number: CN1218162A
Application number: CN 97122170
Authority: CN
Inventors: 陈宪明
Original assignee: GUOTONG CEMENT PRODUCTS CO Ltd
Current assignee: GUOTONG CEMENT PRODUCTS CO Ltd
Priority date: 1997-11-25
Filing date: 1997-11-25
Publication date: 1999-06-02

Abstract

A method for manufacturing steel pipe coated by polyethylene film includes such technological steps as blasting sand onto the surface of raw steel pipe to make it rough, preheating the steel pipe to the temp. needed by smelting polethylene, and rotating the steel pipe over the tank with fulling of electrostatic coating powder and having rollers, where the polyethylene powder is adsorbed onto surface of the pipe by the electric field formed around the steel pipe and molten by the high temp. of steel pipe to form a coated layer. Its advantages include simple process, low cost and uniform coating.

Description

A kind of manufacture of steel pipe of polyethylene coating

The present invention relates to a kind of manufacture of steel pipe of polyethylene coating, particularly a kind of corrosion-resistant, anti-infiltration and can prolong steel pipe working life is applicable to the manufacture of steel pipe of the polyethylene coating of various grounds or underground pipes line.

Recently, transfer line is being played the part of more and more important role in our living environment, as from traditional water pipe, transport pipe, gas pipe, to the underground pipe arrangement of the protective tube of electric power, communication usefulness and nearest light fiber-optic cable etc.Make various transfer line on the ground or undergroundly be not subjected to extraneous erosion damage; must use the protective tube or the pipe arrangement of various characteristicses such as having corrosion-resistant, anti-seepage, anti-collision and insulation; and this protective tube or the most direct method of pipe arrangement are to do corrosion protection covering in steel tube surface to handle; make it to reaching above-mentioned various characteristics; the steel pipe of more durable practicality is provided; at present, normally do the tunicle coating of PE (polyethylene) in steel tube surface.

The general outer manufacture of steel pipe that covers the PE tunicle be earlier with steel pipe through sand blast, the firecoat of former steel tube surface oxide layer is removed, and is made former steel tube surface form fine depression, strengthen its adhesion when being beneficial to the lining of PE layer; Through heat treated, make steel pipe reach predetermined temperature again; Further carry out the outer manufacturing process of covering of PE layer, formation is dissolved state, the coating processing of favourable PE layer like this because of PE meets heat; After steps such as cooling, inspection, finish whole manufacturing process, and central the most important person is the outer manufacturing process of covering of PE layer, this manufacturing process is related to the cost and the quality of integral production: be depicted as the band method as first and second figure, be after steel pipe 10 is through sandblast, heat treated, again in pipe face coating solid 11, after PE band 12 is seized in steel pipe 10 peripheries, carry out next manufacturing process then; Then the pressure zone method shown in third and fourth figure, steel pipe 20 is after the handling process through sandblasting machine 21, heater 22, extrusion molding PE coating through lining molding machine 23, this lining molding machine 23 is sent into solid 24 and PE raw material simultaneously via filler pipe 231 and supply pipe 232, softening and be coated on steel pipe 20 peripheries and form PE layer 25 through overheated temperature, enter next manufacturing process afterwards again; But the outer manufacturing process of covering of above-mentioned relevant PE layer has following defective, as the band method: 1, need solid; 2, individual layer is seized the thickest the 2.2mm that has an appointment, and thicker if desired coating need be made multilayer and seize, and is very uneconomical; 3, seizing process easily produces bubble, causes the quality instability; 4,, make the production bore restricted because of the cause of supporting seizing equipment.Pressure zone method for another example: 1, also need solid; 2, molding machine 0 mould extruding process coating thickness is difficult to surpass 3mm; 3, because of the PE coating is to utilize the moulding of lining molding machine to coat, be subject to the size of molding machine, it is also restricted that it produces bore.

Figure 5 shows that spreading melts the lining method, steel pipe 30 is after process sandblast and heat treated, place again on the molten lining machine 31 and rotate, should have a spreading groove 311 in molten lining machine 31 tops, the below has an accumulator tank 312, spreading

groove

311 and 312 of accumulator tanks have the machine 313 that rises to be connected, utilize spreading groove 311 with PE powder spreading from top to bottom, utilize the temperature of steel pipe 30, with powder melts, and the fusion powder that is attached to steel pipe 30 not drops in bottom accumulator tank 312, utilize the spiral recovering device and the machine 313 that rises with powder recovery to spreading groove 311 spreading again again; Though the molten lining method of this spreading need not used solid, and simplified manufacturing process, it is also unrestricted to produce bore; But the spreading of spreading groove is inhomogeneous, can cause PE tunicle rough surface, influences quality, the huge dust collection equipment of this arts demand and the cooperation of recovery plant again, and the cost of investment and the device space all obviously increase.

So how to possess simple, the unrestricted advantage of production caliber of molten lining manufactured technology, the quality that can improve the PE tunicle again reaches cost and the space waste that effectively reduces corollary equipment, will be important problem.

Main purpose of the present invention is to provide a kind of above-mentioned defective that overcomes, and manufacturing process is simple, the unrestricted outer manufacture method of covering the steel pipe of PE tunicle of production caliber, and this method investment goods cost is low and can guarantee the better method of quality of product.

The manufacture of steel pipe of a kind of polyethylene coating of the present invention is as follows:

At first, do sand blast with standard manufacture technology in steel tube surface.Then, steel pipe is directly heated through LPG (liquefied petroleum gas (LPG)) heater, make to reach the required temperature of the molten lining of PE.

Then, the steel pipe that will have the heat temperature, be placed on the electrostatic coating powder groove of rolling wheel seat and rotate, utilize the static generator to make the steel pipe positively charged, make PE powder belt negative electricity, under suitable distance and voltage conditions, the air quantity that utilizes powder groove below to blow promotes powder and is the state that flies upward that floats, because electrostatic interaction forms electric field around steel pipe, the positive electricity of steel pipe and the negative electricity of powder is inhaled mutually, the PE powder nature that flies upward is adsorbed by the steel pipe tube wall, form rete, the time length according to application determines thickness again, and the PE powder is attached on the hot temperature steel pipe, slowly glue is molten, forms the tunicle of desired thickness.

The manufacture of steel pipe of a kind of polyethylene coating of the present invention has following advantage and characteristics:

1, manufacturing process of the present invention is simple, and does not need solid, and the speed of finishing tunicle is fast, and with caliber 600mm, to form by film thickness 3.1mm be example, the time only needs about 180 seconds, and it is also unaffected to produce bore, and thickness can be coated with the decision of ETL estimated time of loading length according to rotation.

2, utilize the required equipment investment of manufacturing process of the present invention few, do not need other extra dust suctions, recovery plant, cost is low, efficient is high.

3, the PE powder of manufacturing process of the present invention can evenly be adsorbed in steel tube surface, forms tunicle smooth surface, the average lining of thickness, all can reach standard easily no matter it is visual examination, pin hole inspection, thickness inspection or adhesion inspection.

4, the PE powder of manufacturing process of the present invention can not drop, and does not also have the waste powder.

Brief description of drawings is as follows:

Fig. 1 is the processing schematic representation of band method;

Fig. 2 finishes the outer steel pipe sectional view that covers manufacturing process with the band method;

Fig. 3 is the processing schematic representation of pressure zone method;

Fig. 4 finishes the outer steel pipe sectional view that covers manufacturing process with the pressure zone method;

Fig. 5 is the processing schematic representation of the molten lining method of spreading;

Fig. 6 is the equipment schematic representation of the embodiment of the invention;

Fig. 7 is the process side view of the embodiment of the invention.

Now to making description of drawings most preferred embodiment of the present invention;

At first, please consult Fig. 6, Fig. 7 simultaneously, steel pipe 40 is done sand blast with standard manufacture technology, the firecoat that is attached to former steel pipe 40 surface oxide layers is removed, and the epidermis that makes former steel pipe forms fine depression, during with the molten lining of PE powder, strengthens its adhesion in order to steel pipe 40.Then with steel pipe 40 through the LPG heater heats, make steel pipe 40 reach the required temperature of the molten lining of PE powder.

Then, the steel pipe 40 that will have a heat temperature is placed in rotation on the electrostatic coating powder groove 42 of rolling wheel seat 41, this powder groove 42 is connected with the negative pole of static generator 50, and then make PE powder 422 electronegative, the positive pole of static generator 50 then is connected with the steel structure of rolling wheel seat 41, invar pipe 40 contacts with rolling wheel seat 41, so make steel pipe 40 positively chargeds, form electric field around making steel pipe 40, static between steel pipe 40 and the powder groove 42 is under suitably distance and voltage conditions are controlled, the air quantity that cooperation utilizes the air-pressure chamber 421 of powder groove 42 belows to blow, promote PE powder 422 and be the state that flies upward that floats, effect because of static, PE powder 422 natures that fly upward are adsorbed by tube wall, form rete, again according to the length decision thickness that is coated with ETL estimated time of loading, last PE on the hot temperature steel pipe that adheres to gradually glue fuse knot, form the tunicle 43 of desired thickness.

After the electrostatic coating operation is finished, PE tunicle 43 also is soft state, eliminate static and close air-supply this moment, the molten bushing pipe of PE that then will finish work continues to place on the rolling wheel seat and rotates, make the continuous weight shift of weight of tunicle, and according to atmosphere normal temperature be cooled to 50 the degree below, its PE tunicle 43 will form the solid-state of smooth skins.

The powder of electrostatic coating powder groove of the present invention is not limited to the PE powder, and other also can be used under condition of different temperatures as EPOXY (epoxy resin) powder.

Though the present invention discloses as above with a most preferred embodiment, yet it is not in order to limiting the present invention, anyly has the knack of this operator, suitably makes a little changes and adjustment, will not lose main idea of the present invention place, does not also break away from inventive concept of the present invention and protection domain.

Claims

1, a kind of manufacture of steel pipe of polyethylene coating is characterized in that comprising the following step:

Sandblast is done sand blast with standard manufacture technology with steel pipe, when serving as a contrast for steel pipe and polyethylene powders are melted, strengthens its adhesion, and the firecoat that will be attached to former steel tube surface oxide layer is removed, and makes the epidermis of former steel pipe form fine depression;

Heating through the LPG heater heats, makes steel pipe reach the required temperature of the molten lining of polyethylene powders steel pipe;

Sintering, the steel pipe that will have a heat temperature is placed on the electrostatic coating powder groove of rolling wheel seat and rotates, this powder groove is to be connected with the negative pole of static generator, and then make polyethylene powders electronegative, the positive pole of static generator then is connected with the steel structure of rolling wheel seat, and make steel pipe because of the contact positively charged, form electric field around making steel pipe, static between steel pipe and the powder groove is under suitably distance and voltage conditions are controlled, the air quantity that cooperation utilizes the air-pressure chamber of powder groove below to blow promotes polyethylene powders and is the state that flies upward that floats, and utilize the effect of static, the polyethylene powders nature that flies upward is adsorbed by tube wall, forms rete, again according to the length decision thickness that is coated with ETL estimated time of loading, last polyethylene powders on the hot temperature steel pipe that adheres to gradually glue fuse knot, form the tunicle of desired thickness;

Cool off, the molten bushing pipe of the intact polyethylene of doing is continued to place on the rolling wheel seat rotate, make the continuous weight shift of weight of tunicle, and cool off according to atmosphere normal temperature.

2, the manufacture of steel pipe of a kind of outer polyethylene tunicle as claimed in claim 1, wherein polyethylene powders can replace with epoxy powder.