CN85102477B - One step method formation process of the heat-insulatad and anti-corrosion layers for the steel pipring - Google Patents

Abstract

The present invention relates to an 'one step method' forming technology of heat insulating and corrosion preventing layers of steel pipes, which belongs to the technical field of the composite structure formation of the heat insulating and corrosion preventing layers of steel pipes. The present invention both has an extrusion moulding technique and has a spray irrigation foaming technique, and the technological method makes polyethylene protective layers and polyurethane hard foam layers simultaneously, synchronously and once formed. The present invention adopts a special composite machine head and a special automatic deviation rectifying system having three freedoms, and is matched with a set of reasonable technological parameters. The present invention can be used for the heat insulation and the corrosion prevention of various steel pipes having the diameter from 60 to 273mm, and has the advantages of simple procedure, mechanization, high automation, high work efficiency, raw material saving, small eccentricity, good properties of the heat insulation and the corrosion prevention, and small environment pollution.

Description

Steel pipeline thermal-insulation anticorrosion layer 〃 one-process 〃 forming method

The invention belongs to steel pipeline thermal-insulation anticorrosion composite bed forming method.

The most frequently used polyurethane rigid foam plastic of under ground piping is done adiabatic thermal insulation layer, does anticorrosioning sheath with polyvinyl plastics and additive (claiming yellow jacket again).This composite structure is considered to optimal thermal-insulation anticorrosion system.Its forming method normally adopts yellow jacket and steel pipe concentric locating to pour into foam-formed method (to see the U.S. " Pipe and PipeLine International " 1980, voL25, No4, P29) or adopt and extrude the yellow jacket of cladding after the first foam layer moulding or winding polyethylene band method (is seen the U.S. " PipeLine Industry " 1976, voL44, No3, P61～64, B. P. GB1574991,1980), or the preformed foam tile fragment is buckled in outer wrapping fixation on the steel pipe and (sees the Soviet Union " CTpo и Te д bcTBo Tpy o poBo д oB " 1981, No4, P29～30), above-mentioned several method all is foam layer and the moulding at twice of yellow jacket, can be referred to as and do " two-step method ", its advantage is that product thermal-insulation anticorrosion performance is good, shortcoming is that operation is more loaded down with trivial details, handwork is more, manufacturing efficiency is not high, material expends more, cost is higher, working condition is relatively poor, and causes environmental pollution.In the Japan Patent " day clear 48-35935 of bulletin " a kind of extruder head is arranged, provide polyethylene melting charge and the common polythene melting charge that is mixed with stabilizer by two extruders simultaneously respectively to it, after steel pipe passes through, can clad the outer jacket cover of polyethylene foamed internal layer and polyethylene from this head.Have only about 3 times though some shortcomings that the method for a this extruding and moulding has overcome above-mentioned " two-step method ", its disadvantage are foam overruns, the product adiabatic heat insulating effect is relatively poor.In B. P. " GB1542585,1979 " and the U. S. Patent " 4146562,1979 " a kind of extruder head that cools off calibration sleeve that has is arranged.After steel pipe passed through from head, sizing can not foam the polyethylene melting charge that is mixed with stabilizer that is extruded because appearance is cooled, and forms the crust that densification is smooth.Internal layer then can form a foam insulation towards pipe direction foaming and intumescing.The advantage of this technological method is that operation is simplified more, but that disadvantage remains foam overrun is too low.The product insulation capacity is relatively poor.Because above-mentioned day, English, U.S. moulding technique all are an extruding and moulding on technical spirit, usefulness all be the polyethylene raw material that is mixed with stabilizer, can be referred to as and do " extrusion molding ".

The objective of the invention is to adopt a kind of and above-mentioned different moulding technique, both had the two-fold advantage of " two-step method " and " extrusion molding ", and overcome this two kinds of shortcomings that method is difficult to overcome.

Technical spirit of the present invention both was different from the foam layer and the moulding at twice of yellow jacket of " two-step method ", the foam material of only not spraying that also is different from " extrusion molding " by extruding, it is a kind ofly not only to have extruded yellow jacket but also the foam material of spraying, make yellow jacket and foam layer synchronous one-time formed technological method simultaneously, so be called " one-process " forming method, its technological process is seen shown in the accompanying drawing 1.Among the figure, 1 for inlet pipe, 2 for upper connection, 3 for sending machine to, 4 is derusting machine, 5 is clamp device, and 6 is frequency heating device, and 7 is positioning means, 8 is composite machine head, and 9 is water-cooling apparatus, and 10 is automatic error-correcting system, 11 for looking for piecing devices automatically, 12 for unloading joint, and 13 for going out pipe, and 14 is extruder, 15 is the foam irrigation sprinkler, and 16 is raceway.

One of technological points of the present invention is a process route: steel pipe is by a special multiple platform head, the yellow jacket that is extruded just wraps in steel pipe wherein, by the level pressure air the yellow jacket of soft attitude is bulged and to be close to hardening by cooling sizing on the water-cooled calibration sleeve inwall, and by steel pipe traction and steel pipe advanced in unison, at this simultaneously, annular space between steel pipe and yellow jacket sprinkling irrigation polyurethane foam raw material, and foaming and solidifying within it make steel pipe, foam layer and the yellow jacket structure that is combined into one.

Technological points of the present invention also is to have the complete processing parameter matching of a cover, various steel pipes for 60 to 273 millimeters of diameters, main technologic parameters is: the polyethylene extrusion capacity is 2 to 2.5 kilograms of per minutes, the steel pipe feed rate is 1 to 3 meter of a per minute, foam material consumption is 1.2 to 2.3 kilograms of per minutes, and voltage stabilizing cover inner air pressure is 0.1 to 0.3 kilogram every square centimeter.

Technological points of the present invention also is a kind of special composite machine head, and it is the organic synthesis of plastics light wall pipe forming technique, yellow jacket cladding technology, foamed plastics sprinkler irrigation technique.There are five kinds of materials (polyethylene, isocyanates, combined polyether, water, gas) to import this head simultaneously, and the energising heating.The flow of these five kinds of materials and heating-up temperature, totally eight parameters are all controlled to send pipe speed, foamed time.This composite machine head mainly is made up of horizontal extruder head, water-cooled calibration sleeve, voltage-stabilizing system and foam material rainer.Accompanying drawing 2 is this composite machine head structural representation.Among the figure, 17 is foam material rainer, and 18 are the voltage stabilizing cover, and 19 are pressure stabilizing exhaust device (18 and 19 are collectively referred to as voltage-stabilizing system), and 20 is horizontal extruder head, and 21 is the water-cooled calibration sleeve.Laterally extruder head is the flat mouth structure of sleeve pipe right-angle type, has ring-type to distribute ditch and throttling seam, and the compression ratio of cone compressing section is about 3, and flat segments length is 30 to 60 millimeters.The water-cooled calibration sleeve is the semi-spiral water-cooled structure, and length is 250 to 320 millimeters, and chromium plating is handled after the inwall honing.Its structural representation is seen shown in Figure 3.Among the figure, 22 is the spiral manger board, and 23 for connecting end cap, and 24 is the sizing inwall, and 25 is outer wall.Voltage-stabilizing system mainly is made up of voltage stabilizing cover and pressure stabilizing exhaust device, and the voltage stabilizing cover has quick coupling mechanism for columnar structured with horizontal extruder head joint, uses the temperature resistant encapsulation rubber seal, and uses large stretch of silicone rubber seal between the steel pipe.Spherical valve, air inlet air vent valve, pressure gauge etc. all are contained in voltage stabilizing and put.Foam material rainer adopts the mode of spray or filling all can.The spray gun that the present invention uses is made with φ 10 * 2 or φ 12 * 2 steel pipes, long 900 millimeters.A, two kinds of component foams of B material material feeding mouth and suction port are arranged on the gun platform, spray into the annular space between steel pipe and the yellow jacket tube after material mixes in rifle.The compressed air pressure of sending into spray gun is 3 to 5 kilograms every square centimeter, and spray gun inserts from voltage stabilizing cover end.

Technological points of the present invention also is a kind of special Three Degree Of Freedom automatic error-correcting system.Its effect is to force yellow jacket and steel pipe to keep concentric, and the foam material is foaming and solidifying in the guaranteed annular space of this concentricity just.Accompanying drawing 4 is automatic deviation correction working principle skeleton diagrams of this system, mainly constitutes the reverse feedback automatic error-correcting system by the inclined to one side sensor of survey, control wiring, mechanical actuating mechanism.Its working procedure is: by surveying inclined to one side sensor the offset δ of yellow jacket to steel pipe measured automatically, and transform into voltage signal U ₁, U ₁After handling, control wiring becomes signal U ₂, U ₂Go control executing mechanism oppositely to promote yellow jacket tube, it is concentric that it is returned to steel pipe.Fig. 5 surveys the shared signal source Usr of primary coil of probe partially for surveying inclined to one side Fundamentals of Sensors schematic representation for two among the figure.When yellow jacket and steel pipe are concentric, i.e. δ ₁With δ ₂Equate its secondary induced signal Usc ₁With Usc ₂Equate that direct current difference output signal U sc is zero.If occur off-centre, i.e. δ between yellow jacket and the steel pipe ₁With δ ₂Unequal, then Usc is non-vanishing, and the big more Usc of offset is also big more.If the inclined to one side sensor of survey that Fig. 5 is such is symmetrically distributed in upper and lower and left and right four positions near yellow jacket tube, and the correction location that is fixedly mounted on actuator is taken, not only can realize vertical and two degrees of freedom of level are surveyed partially and correction automatically, and can realize four any directions of quadrant of two-dimensional coordinate are surveyed partially and correction automatically.Fig. 6 is vertical (or level) correction control loop skeleton diagram.Mainly form by control amplifier, trigger and silicon controlled rectifier.In order to improve the system dynamics quality, taked the reverse feedback measure, for easy to operate, designed manual function.Fig. 7 is a foam positions automatic tracking loop skeleton diagram, mainly is made up of photoelectric sensor, logic switch, control amplifier, trigger and silicon controlled rectifier.Photoelectric sensor can utilize foaming interface two to survey printing opacity and lighttight characteristics, produces the respective logic signal, make actuator along pipe axially from the motion tracking foam positions, be beneficial to rectify a deviation at optimal position.The master that Fig. 8 and Fig. 9 are respectively the automatic error-correcting system mechanical actuating mechanism looks and the side-looking structural representation.Among the figure, 29 for sitting the correction location, and 30 are the location slide plate, 31 is flat slide plate, and 32 is the vertical lift plate, and 33 is body, 34 is road wheel, 26 is cylinder, and 27 are level correction motor, and 28 is vertical correction motor, in three degrees of freedom of motion of this mechanism, two degrees of freedom of vertical-horizontal are the guide pillar translation structure, and power screw play the correction effect.Degrees of freedom along tube axis is roller track structure, sprocket driving, can follow the tracks of foam positions.Three degrees of freedom of motion are controlled by three control loops respectively, are driven by three direct current generators.

The present invention and " two-step method " contrast have operation simplification, mechanization, automaticity height, the work efficiency height, and the stock utilization height, product cost is low, and working condition is good, advantages such as factory building non-environmental-pollution.With " extrusion molding " contrast, has foam expansion rate height (can reach more than 20 times), advantage such as product thermal-insulation anticorrosion performance is good.Automatic error-correcting system of the present invention when the thermal-insulation anticorrosion layer thickness is 30 to 45 millimeters, can make offset reaching more than 80% within ± 3 millimeters.

Claims (4)

1, a kind of forming method of steel pipeline thermal-insulation anticorrosion layer, it is characterized in that: adopt polyethylene is extruded the specific complex head that combines with polyurethane foam sprinkling irrigation foaming, steel pipe passes through composite machine head, the yellow jacket cladding of the polyethylene that is extruded steel pipe, by the level pressure air the yellow jacket of molten state is bulged and to be close to hardening by cooling sizing on the water-cooled calibration sleeve inwall, yellow jacket is drawn advanced in unison by steel pipe, at this simultaneously, annular space sprinkling irrigation polyurethane foam raw material between steel pipe and yellow jacket, in its foaming and uncured position forces yellow jacket and steel pipe to keep concentric by the Three Degree Of Freedom automatic error-correcting system, solidifying is an overall structure.

2, forming method according to claim 1, it is characterized in that the main technologic parameters that described composite machine head is selected for use is that polyethylene per minute extrusion capacity is 2 to 2.5 kilograms, foam material per minute consumption is 1.2 to 2.3 kilograms, the steel pipe feed rate is 1 to 3 meter of a per minute, and voltage stabilizing cover inner air pressure is 0.1 to 0.3 kilogram every square centimeter.

3, forming method according to claim 1 is characterized in that: described composite machine head mainly comprises horizontal extruder head, water-cooled calibration sleeve, voltage-stabilizing system and bubble jet filling device.

4, forming method according to claim 1, it is characterized in that described Three Degree Of Freedom automatic error-correcting system, comprise that mainly surveying inclined to one side sensor follows the tracks of circuit, mechanical actuating mechanism, formation to the reverse feedback automatic error-correcting system of pipe two degrees of freedom of vertical and level radially with along the axial automatic control system from the motion tracking foam positions of pipe with foam positions photoelectric sensor, correction control automatically with foam positions.

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