CN104480382A - Method for preparing centrifugal nodular cast iron pipe - Google Patents
Method for preparing centrifugal nodular cast iron pipe Download PDFInfo
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- CN104480382A CN104480382A CN201510033559.9A CN201510033559A CN104480382A CN 104480382 A CN104480382 A CN 104480382A CN 201510033559 A CN201510033559 A CN 201510033559A CN 104480382 A CN104480382 A CN 104480382A
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Abstract
The invention discloses a method for preparing a centrifugal nodular cast iron pipe. The method discloses the preparation process of the centrifugal nodular cast iron pipe of high quality, the preparation process comprises a series of operation processes of molten iron preparation, nodulizing of molten iron, centrifugal casting, annealing treatment, pipe body shaping and coating protection and the like. The method is suitable for preparation of cast iron pipes of the specification of DN 80-1000 mm, the application range is wide, and the preparation process is simple. The cast iron pipe prepared through the method has the characteristics of being high in appearance quality, fine in material structure, high in production efficiency, long in service life and the like, and compared with existing steel pipes and gray iron pipes, the cast iron pipe prepared through the method has better decay resistance and tensile property.
Description
Technical field
The present invention is a kind of preparation method of centrifugal ductile cast iron pipes, is specifically related to the preparation technology of centrifugal ductile cast iron pipes, belongs to cast iron pipe preparing technical field.
Background technology
From the nineties in 20th century, China has adopted interior spray material centrifugal casting to produce DN2600mm, length is the centrifugal ductile cast iron pipes of 8000mm, achieve the batch production of centrifugal ductile cast iron pipes, certainly, due to the use properties that centrifugal ductile cast iron pipes is excellent, adopted by waterworks soon, so far water-supply pipe preferred material has been become, and as other industrially developed country, just complete from graphitic cast iron to spheroidal graphite cast iron within very short time, transformation from continuous casting process to centrifugal casting technique, can say, since entering the nineties, the cast iron pipe of China is produced and has been entered a period of developing by leaps and bounds.
The mechanical property of international standard ISO2531291 to ductile iron pipe has very strict requirement, include: tensile strength >=420MPa, yield strength >=300MPa, elongation >=10% (for caliber specification DN40 ~ DN1000), surface hardness≤230HB.In recent years, the cast iron pipe manufacturing enterprise of China is by introducing and domestic continuous development from external, build the water-cooled metal mould Centrifugal Casting Iron Pipe production unit that overall throughput reaches 400,000 tons/year, but because technological measure is improper, the ductile iron pipe produced can meet only more than 10 ten thousand tons of international standard ISO2531291 requirement, only account for domestic cast iron pipe ultimate production about 10%, and for existing ductile iron pipe production technique, also there is following critical technological point:
(1) according to the difference of cast iron pipe caliber, the carbon equivalent in conservative control iron liquid and trace element, in actual production technique, carbon equivalent can improve the degree of graphitization of spheroidal graphite cast iron, but too high carbon equivalent can cause graphite floatation again; Trace element silicon promotes graphite element, and micro-sulphur can consume etc. nodularization element.Existing patent documentation CN102000797A(mono-kind take vanadium titano-magnetite as the method for raw material production nodular cast iron pipe fittings) be example, this patent documentation discloses a kind of with the cast iron pipe production technique taking vanadium titano-magnetite as raw material, in half iron and steel water, carbon content control is 3.5 ~ 3.8%, the part by weight of nodulizing agent middle-weight rare earths magnesium ferrosilicon is 1.6 ~ 2.0%, in cast iron pipe iron liquid, aluminiferous amount is not more than 0.02%, phosphorus content is not more than 0.08%, sulphur content is not more than 0.02%, achieve the Appropriate application of v-ti magnetite ore resources, reach the object economized on resources.
(2) in process of production, desulfurization, nodularization are carried out to iron liquid and the treatment process that breeds improper, the serious quality that have impact on cast iron casting pipe.Existing patent documentation CN101921945A(liquid iron inoculation process for ductile iron pipes, 2010.08.31) disclose a kind of molten steel preparation technique, this inoculated technology comprises: educate at original nodularization subsumption increases tundish inoculated technology between these two steps of current-following inoculation, realize breeding the long-acting of molten iron, effectively can reduce residual Mg content in spheroidization molten iron, improve tensile strength and yield strength, simultaneously for reducing high temperature anneal temperature, the size of stability ball graphite cast iron pipe finished product creates conditions.
(3) misoperation in cast iron casting pipe integer and coating procedure, easily causes the shortening in cast iron casting pipe work-ing life.Treatment process after existing patent CN102981492A(nodular graphite iron cast tube annealing, 2012.12.13) disclose the integer process being applicable to cast iron casting pipe, can realize manage number automatic management, improve the quality control level of product and the trackability of product, raise the efficiency, reduce the labour intensity of workman.
Based on above-mentioned situation, in conjunction with the sustainable growth of current China to cast iron pipe demand, on this basis, to cast iron pipe preparation method: carry out major tuneup from melting, liquid iron balling inoculation, casting, thermal treatment, integer and coating etc., form the complete production technique can stablized and obtain high quality cast iron pipe, to meet the active demand of current cast iron pipe industry.
Summary of the invention
The object of the present invention is to provide a kind of preparation method of centrifugal ductile cast iron pipes, present method discloses the preparation process of preparation high-quality centrifugal ductile cast iron pipes, the a series of operating process such as this process includes molten iron preparation, liquid iron balling, centrifugally to build, anneal, body integer and coating protection, be applicable to the preparation of the cast iron pipe of DN80 ~ 1000mm, not only applied widely, also have that visual appearance is high, material structure is fine and closely woven, production efficiency is high and the many advantages such as long service life.
The present invention is achieved through the following technical solutions: a kind of preparation method of centrifugal ductile cast iron pipes, and preparation process is as follows:
(A) blast furnace or cupola furnace is used to carry out pyrotic smelting to the pig iron, obtain the molten iron of sulphur content≤0.02%, carbon equivalent undulating quantity≤± 0.1%, hot metal composition is stablized, in preparation process, for controlling the content of sulphur, usually add sweetening agent, and with nitrogen pass in molten iron by continuous many skies fill in row desulfurization ensure, in the present invention, for improving the moving phase of iron liquid, carbon equivalent in molten iron selects 4.3 ~ 4.4% usually, effectively can not only promote the raising of magnesium absorption rate, can also improve nodularization effect;
(B) molten iron obtained for step (A) is sent into nodularization station, by the nodularization wire drive feeder at nodularization station, molten iron is carried out spheroidizing to entering nodularization bag, the hot metal ladle obtained after nodularization contains: carbon 3.2 ~ 3.5%, sulphur < 0.01%, silicon 2.3 ~ 2.36%, phosphorus < 0.073%, magnesium >=0.035%, manganese < 0.35%, rhenium < 0.026%, from above-mentioned component, the molten iron micronutrient levels obtained after nodularization is lower, particularly silicon, the conservative control of the trace element such as manganese, the consumption of nodulizing agent can not only be effectively reduced, can also reduce costs, reduce the acid slag that silicon ribbon enters, improve and suppress qualification rate, simultaneously, because the sulphur content of the molten iron after nodularization is less than 0.01%, be more conducive to produce steady quality, the cast iron pipe that qualification rate is higher, each component proportioning is suitable, under normal circumstances, for the cast iron pipe of DN80 ~ 1000mm, its nodularization temperature is 1460 ~ 1520 DEG C, before entering molten iron, nodulizing agent and nucleating agent is added successively in nodularization bag, described nodulizing agent is rare earth Mg-Si nodularizer, add-on is 32 ~ 45m/T, by weight percentage, rare earth 18 ~ 20 % is included in described rare earth Mg-Si nodularizer, magnesium 20 ~ 25%, silicon 46 ~ 50%, described nucleating agent is ferrosilicon or silicocalcium, add-on is 1.5 ~ 2.5Kg/T, by weight percentage, silicon 46 ~ 50% is included in described nucleating agent, calcium 1.2 ~ 1.5 %, in the present invention, nodulizing agent and nucleating agent add the mechanical property that effectively can improve cast iron casting pipe, in metallographic structure, graphite is spherical, compared with the flake graphite of common iron pipe, its matrix to isolate destruction much little, molten iron is through nodularization, centrifugally to build, annealing can make the ferrite of matrix be greater than 85%, its cast iron pipe prepared finally is made to have tensile strength, yield strength, the excellent many advantages that waits of the mechanical property performances such as unit elongation,
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, and with drawbench, the cast iron casting pipe after shaping is extracted from pipe die, this step is centrifugal casting process, when practical application, for adapting to higher rhythm of production, enhance productivity, after the liquid iron balling of temperature higher (as: 1460 ~ 1520 DEG C), its placing temperature also higher (1310 ~ 1460 DEG C), simultaneously, the setting of placing temperature also should meet following 2 points, avoid placing temperature too low (< 1310 DEG C) that socket thickness can be made to increase, otherwise (> 1460 DEG C) can make bellmouth position wall thickness increase, certainly, in above-mentioned centrifugal step of building, the mass defect that the controling parameters such as time and speed of perfusion further can also reduce cast iron pipe is built in rational arrangement, avoid occurring bellmouth misrun or blocked up, socket misrun or socket end wall thin, wall thickness, the situations such as cast iron pipe axial walls is uneven, under normal circumstances, when centrifugal casting starts, spheroidization molten iron is full of in the process of bellmouth die cavity and needs one section of main frame (that is: CENTRIFUGAL ACCELERATING machine) deceleration time, time controling is at 0.36 ~ 2s, if control long during this period of time, the straight-tube portion be then connected with bellmouth when bellmouth is full of has poured into a mould too much iron liquid.This part wall thickness can be caused to increase; Otherwise, bellmouth die cavity is then likely caused not to be full of, faucet part divides wall thickness thinner, evenly walk at cast straight-tube portion main frame, at the end of cast, for making cast tube socket fully shaping, main frame finally needs one section of distance of going slowly, and with turn over (tundish and fan-shaped bag) the falling time of wrapping and match, the reversal rate of tundish and fan-shaped bag is 1 ~ 2.5 r/min, and going out iron is 60 ~ 80kg/s, when going slowly apart from certain, if turn over the bag falling time and main frame socket is long for deceleration time, jack part will thicken, otherwise will be thinning.
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, successively through heating, insulation, rapid cooling, annealing furnace is sent after slow cooling, the time controlling the annealed stove of cast iron pipe is 40 ~ 60min, the cast iron pipe sending annealing furnace after air cooling as cast iron pipe products formed, described annealing furnace is primarily of the heating zone set gradually, holding-zone, rapid cooling section and slow cooling section composition, wherein, the length of heating zone is 13 ~ 14m, the length of holding-zone is 8 ~ 9m, the length of rapid cooling section is 4 ~ 5m, the length of slow cooling section is 15 ~ 16m, in actual mechanical process, the temperature of holding-zone controls at 960 ~ 980 DEG C, the temperature of described rapid cooling section controls at 700 ~ 730 DEG C, the temperature of described slow cooling section controls at 560 ~ 680 DEG C,
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe, in this step, described impression adopts steel ball ball to carry out impression in the position at socket inwall 20 ~ 40mm place of cast iron casting pipe, pressure is 4 ~ 6MPa, and after impression, cast iron casting pipe does not occur crackle; Described reconditioning adopts air grinder to carry out reconditioning to cast iron pipe bell and spigot, adopts grinding-wheel grinder pole pair cast iron pipe inner wall to carry out reconditioning; Described mark garden and campus adopt ring gauge to carry out mark garden and campus to cast iron casting pipe; Described cut ring be adopt cut ring sampling to batch cast iron pipe carry out metallographic and performance checking.
(F) carry out exterior protection to the cast iron pipe outer wall after integer process, comprise successively to spray zinc and the pitch spraying of the enforcement of cast iron pipe outer wall, the thickness of described zinc layers is 110 ~ 130g/m
2, the thickness of described brea bed is 50 ~ 70 μm; Carry out inwall protection to the cast iron pipe inner wall after integer process, comprise the cement coated lining implemented cast iron pipe inner wall, the thickness of described cement coated lining is 3 ~ 8 mm.
Nodulizing agent and nucleating agent add the mechanical property that effectively can improve cast iron casting pipe, in metallographic structure, graphite is spherical, compared with the flake graphite of common iron pipe, its matrix to isolate destruction much little, molten iron is through nodularization, centrifugally to build, annealing can make the ferrite of matrix be greater than 85%, its cast iron pipe prepared finally is made to have tensile strength, yield strength, the excellent many advantages that waits of the mechanical property performances such as unit elongation, in the present invention, the bottom of described nodularization bag and the side of nodularization bag dykes and dams form the groove holding nodulizing agent and nucleating agent, described molten iron is tapped a blast furnace along the nodularization bag dykes and dams not forming groove side by nodularization wire drive feeder.
The present invention adopts and pours nodularization method, help flatcar that nodularization bag is sent into the anti-room of nodularization by electricity, and tapped a blast furnace by the nodularization wire drive feeder at nodularization station in the anti-indoor of nodularization, in actual mechanical process, described nodularization wire drive feeder taps a blast furnace with the iron that goes out of 25 ~ 35kg/s, tap a blast furnace to 1/2 ~ 1/3 place of nodularization bag height, pause 3 ~ 5s, then iron is measured to bag full (nodularization packaging is full) with tapping a blast furnace of 80 ~ 120kg/s, the hot metal ladle obtained after nodularization contains the magnesium of 0.035%, its carbon equivalent undulating quantity≤0.032%.
In described step (C), after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, described pipe die is that high temperature steel is made, the temperature < of described main frame water coolant 100 DEG C, in actual application, because the main frame temperature of cooling water of pipe die outside surface is lower than 100 DEG C, and pipe die internal surface temperature sharply rises after pouring molten iron, transient temperature can reach about 750 DEG C, then decline gradually again, so repeatedly, the huge cyclic thermal stres produced can produce serious destruction to pipe die, thermal stresses exceedes (yield strength), pipe die internal surface enters plastic deformation regime immediately, the stress that internal surface produces is stress at first, along with the continuity of time, thermograde changes, stress becomes tensile stress, under high temperature, drawing of pipe die answers intensity lower, at this moment tensile stress can easily exceed the tensile strength of material and produces trickle crackle, the thermal cycling repeatedly that repeatedly cast produces makes crackle constantly expand, finally form hot tearing (be full of cracks), in centrifugal casting process, the most serious place of chapping to contact the pipe die socket of iron liquid at first, be full of cracks exceedes a certain specific degree of depth, will carry out repairing or scrapping, for this reason, the pipe die that the present invention relates to should adopt possesses higher thermal intensity, thermal conductivity is good, the heat-resisting steel material of the characteristics such as thermal expansivity is little is made, as 21CrMo10, 20CrMo, the high temperature steel such as 30CrMo.
Pipe die subjects serious wearing and tearing in tube drawing process, in the deadweight of tube drawing process medium cast iron pipe and surperficial pit, larger frictional force is produced to pipe die, particularly when chill or when the temperature is too low appears in cast tube surface, the wearing and tearing of pipe die are particularly serious, for this reason, in described step (C), before being extracted from pipe die by the cast iron casting pipe after shaping with drawbench, add pipe die powder in the internal surface spray of pipe die.
By weight percentage, described pipe die powder includes the barium of 6 ~ 12%, 1 ~ 2% calcium, the silicon of 60 ~ 65%, its granularity≤0.3mm, the decapacitation of pipe die powder is played outside the effect of instant inoculation, pore and the hole of cast iron pipe outside surface can also be eliminated, because gas after forming air gap and tube drawing after cast iron pipe cooling between cast iron pipe and pipe die can cause gas to enter cast tube outer wall iron liquid in the rapid attachment of pipe die inwall and forms pore, especially even more serious when pipe die chaps, add pipe die powder not only can fill crackle and drive gas, reduce ambient atmos and invade tube wall molten iron, and an interlayer face can be formed at molten iron and pipe die inwall, the oversaturated oxygen of part in reduction iron layer, reduce iron liquid oxidation, decrease the formation of pore, facts have proved, the pockmark that the add-on of pipe die powder and the be full of cracks degree of pipe die internal surface and cast iron pipe outer wall produce, pore is proportional, calculate by the internal surface area of described pipe die, the add-on of described pipe die powder is 20 ~ 30g/m
2.
Further, in described step (F), described spray zinc be use spray gun that zinc is heated to molten state and the outer wall being ejected into cast iron pipe with droplets to form spelter coating, the quantity for spray of described spelter coating is 120g/m
2.
In described step (F), described pitch spraying adopts spraying, roller coating or brush to be coated in outside cast iron pipe spelter coating bituminous composition to form pitch tectum, by weight percentage, solid content≤65% of described bituminous composition, in actual application, pitch tectum has inseparable preservative effect with spelter coating to cast iron pipe.
Cement lining not only has interior preservative activity, and there is clean effect of supplying water, in described step (F), described cement lining carries out coated with formation cement lining layer at cast iron pipe inner wall after fine sand, cement, 801 glue are carried out spice by proportioning, with mass ratio range, described fine sand: cement: 801 glue=2:(1.2 ~ 1.5): (0.12 ~ 0.15), further, for being applicable to the cast iron pipe of DN80 ~ 1000mm, the thickness of described cement lining should meet 3 ~ 6mm.
Further, in described step (F), described coating processes also comprises the health carried out external protection coating in cast iron pipe, and step is as follows:
(F.a) the cast iron pipe natural Health preservation after spray zinc, pitch spraying, cement lining process was sent into health stove after 5 ~ 15 minutes, health is carried out to cast iron pipe, conditioned time > 8 hours under adopting the condition of vapor pressure >=0.15MPa, health temperature > 30 DEG C, humidity >=85%;
(F.b) the cast iron pipe internal surface spraying epoxy ceramic coating after completing health, at its outside surface spray epoxy or polyurethane material.
The present invention compared with prior art, has the following advantages and beneficial effect:
(1) the present invention is applicable to the high-quality water-cooling metal centrifugal ductile iron pipe preparing DN80 ~ 1000mm, preparation process includes molten iron preparation, liquid iron balling, centrifugally to build, anneals, the sequence of operations process such as integer and coating processes, preparation technology is simple, the cast iron pipe prepared has that visual appearance is high, material structure is fine and closely woven, production efficiency is high and the characteristic such as long service life, and more existing steel pipe and Gray Cast Iron Tube, there is better corrosion resistance nature and tensile property.
(2) the present invention uses blast furnace or cupola furnace to carry out pyrotic smelting to the pig iron, obtain the molten iron of carbon equivalent undulating quantity≤± 0.1%, hot metal composition is stablized, in preparation process, for controlling the content of sulphur, usually add sweetening agent, and pass into nitrogen and fill in row desulfurization by continuous many skies in molten iron and ensure, Sulfur Content in Hot Iron content≤0.02%, meets the prerequisite of preparation high-quality water-cooling metal centrifugal ductile iron pipe.
(3) the inventive method is reasonable in design, according to the caliber size of prepared cast iron pipe, under the prerequisite meeting higher rhythm of production and cast iron pipe quality, select nodularization temperature and centrifugal placing temperature to be followed successively by 1460 ~ 1520 DEG C and 1340 ~ 1460 DEG C, its practical application effect is good.
(4) the present invention is in liquid iron balling process, what utilize nodulizing agent and nucleating agent adds the mechanical property that effectively can improve cast iron casting pipe, each component proportion of nodulizing agent and nucleating agent is reasonable in design, in metallographic structure, graphite is spherical, compared with the flake graphite of common iron pipe, its matrix to isolate destruction much little, molten iron through nodularization, centrifugally to build, annealing to make the ferrite of matrix be greater than 85%, the cast iron pipe finally making it prepare has the many advantages such as the mechanical property performances such as tensile strength, yield strength, unit elongation are excellent.
(5) in the present invention, the molten iron micronutrient levels obtained after nodularization is lower, particularly the conservative control of the trace element such as silicon, manganese, can not only effectively reduce the consumption of nodulizing agent, can also reduce costs, reduce the acid slag that silicon ribbon enters, improve and suppress qualification rate, meanwhile, because the sulphur content of the molten iron after nodularization is less than 0.01%, be more conducive to produce steady quality, cast iron pipe that qualification rate is higher, each component proportioning is suitable.
(6) the present invention can before building and/or tube drawing forward direction pipe die internal surface spray add pipe die powder, pipe die powder include 6 ~ 12% barium, 1 ~ 2% calcium, 60 ~ 65% silicon, tube drawing can not only be contributed to, can also play instant inoculation effect, that is: Si, Ba composition in pipe die powder can play instantaneous intensive inoculation effect.
(7) the pipe die powder that the present invention relates to also has the feature eliminating cast iron pipe outside surface pore, pin hole, and facts have proved, by pipe die internal surface area, pipe die powder add-on is 20 ~ 30g/m
2time, be enough to the removing meeting cast iron pipe outside surface pore, pin hole.
(8) the present invention is in centrifugal casting process, the main frame temperature of cooling water < 100 DEG C adopted, for adapting to the preparation of DN80 ~ 1000mm cast iron pipe, usual employing 10 ~ 12 groups of spraying cooling pipes carry out Homogeneous cooling, while guarantee cooling performance, also can improve the speed of cooling of cast iron pipe, improve the production efficiency of cast iron pipe, practical.
(9) annealing furnace that the present invention relates to is primarily of the heating zone set gradually, holding-zone, rapid cooling section and slow cooling section composition, in actual mechanical process, heating zone front end is provided with preheating section, can be used for the body temperature that preheating enters the cast iron pipe of annealing furnace, to ensure the uniform heating of body, the rear and front end of slow cooling section adopts induced draft fan to carry out temperature control operation respectively, be positioned at the induced draft fan of front end, slow cooling section while control cast iron pipe body temperature, can also ensure that eutectoid transformation ferrite generates, slow cooling section adopts induced draft fan to control the tapping temperature of cast iron pipe equally.
(10) in the present invention, the cast iron pipe after integer obtains cast iron pipe finished product after spray zinc, pitch spraying, cement coated lining and health, and wherein, zinc coating thickness is 110 ~ 130g/m
2, the thickness of brea bed is 50 ~ 70 μm, and the thickness of cement coated lining is 3 ~ 8 mm, be proven, zinc layers and brea bed can form good anti-corrosion measure at the outer wall of cast iron pipe, and cement lining then can play preservative activity at the inwall of cast iron pipe, and also have clean effect of supplying water.
Accompanying drawing explanation
Fig. 1 is the structural representation at nodularization station described in the embodiment of the present invention 1.
Fig. 2 is the side-view at nodularization station described in the embodiment of the present invention 1.
Fig. 3 is the structural representation of nodularization bag described in the embodiment of the present invention 2.
Fig. 4 is the structural representation of nodularization bag described in the embodiment of the present invention 3.
Fig. 5 is the structural representation of annealing furnace described in the embodiment of the present invention 7.
Fig. 6 is the thetagram of annealing furnace described in the embodiment of the present invention 7.
Wherein, 1-nodularization wire drive feeder, the anti-room of 2-nodularization, 3-nodularization bag, 4-electricity helps flatcar, 5-groove, 6-induced draft fan.
Embodiment
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited thereto.
Embodiment 1:
It is the centrifugal ductile cast iron pipes of DN500mm that the present embodiment is applicable to preparation specification, and its preparation process is as follows:
(A) use blast furnace or cupola furnace carry out pyrotic smelting to the pig iron, and acquisition sulphur content is 0.02%, carbon equivalent undulating quantity is the molten iron of 0.1%;
(B) molten iron obtained for step (A) is sent into nodularization station, Fig. 1, Fig. 2 is the structural representation at nodularization station, as Fig. 1, shown in Fig. 2, nodularization bag 3 helps flatcar 4 to send in the anti-room 2 of nodularization at nodularization station by electricity, molten iron carries out spheroidizing by the nodularization wire drive feeder 1 at nodularization station to entering nodularization bag 3, the hot metal ladle obtained after nodularization contains: carbon 3.2%, sulphur 0.008%, silicon 2.3%, phosphorus 0.07%, magnesium 0.04%, manganese 0.32%, rhenium 0.025%, before entering molten iron, nodulizing agent and nucleating agent is added successively in nodularization bag 3, in the present invention, nodulizing agent is rare earth Mg-Si nodularizer, by weight percentage, rare earth 18% is included in this rare earth Mg-Si nodularizer, magnesium 20%, silicon 46%, nucleating agent is ferrosilicon or silicocalcium, by weight percentage, includes silicon 46%, calcium 1.2% in this nucleating agent,
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, and with drawbench, the cast iron casting pipe after shaping is extracted from pipe die;
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, annealing furnace is sent successively after heating, insulation, rapid cooling, slow cooling, the time controlling cast iron pipe annealed stove is 40min, the cast iron pipe sending annealing furnace after air cooling as cast iron pipe products formed;
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe;
(F) carry out exterior protection to the cast iron pipe outer wall after integer process, comprise successively to spray zinc and the pitch spraying of the enforcement of cast iron pipe outer wall, the thickness of described zinc layers is 110g/m
2, the thickness of described brea bed is 50 μm; Carry out inwall protection to the cast iron pipe inner wall after integer process, comprise the cement coated lining implemented cast iron pipe inner wall, the thickness of described cement coated lining is 3mm.
Embodiment 2:
The difference of the present embodiment and embodiment 1 is: the spheroidizing that the present embodiment relates to is for pouring nodularization method, the structure of nodularization bag 3 as shown in Figure 3, the bottom of nodularization bag 3 and the side of nodularization bag dykes and dams form the groove 5 holding nodulizing agent and nucleating agent, before entering molten iron, nodulizing agent and nucleating agent is added successively in the groove 5 of nodularization bag 3, when actually operating, molten iron is tapped a blast furnace along the nodularization bag dykes and dams not forming groove 5 side by nodularization wire drive feeder 1, namely in Fig. 3 shown in arrow.
The nodulizing agent that the present embodiment uses is rare earth Mg-Si nodularizer, by weight percentage, includes rare earth 20 %, magnesium 25%, silicon 50% in this rare earth Mg-Si nodularizer.
The nucleating agent that the present embodiment uses is ferrosilicon or silicocalcium, by weight percentage, includes silicon 50%, calcium 1.5 % in this nucleating agent.
Embodiment 3:
The difference of the present embodiment and embodiment 1 is: the spheroidizing that the present embodiment relates to is for pouring nodularization method, the structure of nodularization bag 3 as shown in Figure 4, the bottom of nodularization bag 3 and the side of nodularization bag dykes and dams form the groove 5 holding nodulizing agent and nucleating agent, before entering molten iron, nodulizing agent and nucleating agent is added successively in the groove 5 of nodularization bag 3, when actually operating, molten iron is tapped a blast furnace along the nodularization bag dykes and dams not forming groove 5 side by nodularization wire drive feeder 1, namely in Fig. 4 shown in arrow.
The nodulizing agent that the present embodiment uses is rare earth Mg-Si nodularizer, by weight percentage, includes rare earth 19 %, magnesium 22%, silicon 48% in this rare earth Mg-Si nodularizer.
The nucleating agent that the present embodiment uses is ferrosilicon or silicocalcium, by weight percentage, includes silicon 47%, calcium 1.4 % in this nucleating agent.
Embodiment 4:
The difference of the present embodiment and embodiment 1 is: in the present embodiment, nodularization wire drive feeder 1 taps a blast furnace with the iron that goes out of 25kg/s, tap a blast furnace to 1/2 place of nodularization bag height, pause 3s, then iron is measured to wrapping completely with tapping a blast furnace of 80kg/s, the hot metal ladle obtained after nodularization contains the magnesium of 0.035%, and its carbon equivalent undulating quantity is 0.032%.
Embodiment 5:
The difference of the present embodiment and embodiment 1 is: in described step (C), after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, described pipe die is that high temperature steel is made, the temperature of described main frame water coolant 80 DEG C.
By weight percentage, the pipe die powder that the present embodiment relates to include 6% barium, 1% calcium, 60% silicon, its granularity is 0.3mm, calculates by the internal surface area of pipe die, and the add-on of this pipe die powder is 20g/m
2.
Embodiment 6:
The difference of the present embodiment and embodiment 1 is: in described step (C), before being extracted by the cast iron casting pipe after shaping, adds pipe die powder in the internal surface spray of pipe die with drawbench from pipe die.
By weight percentage, the pipe die powder that the present embodiment relates to include 12% barium, 2% calcium, 65% silicon, its granularity is 0.28mm, calculates by the internal surface area of pipe die, and the add-on of this pipe die powder is 30g/m
2.
Embodiment 7:
The difference of the present embodiment and embodiment 1 is: the annealing furnace that the present embodiment relates to as shown in Figure 5, as shown in Figure 5, annealing furnace is primarily of the heating zone set gradually, holding-zone, rapid cooling section and slow cooling section composition, and the length of heating zone is 13m, the length of holding-zone is 8m, the length of rapid cooling section is 4m, the length of slow cooling section is 15m.
As shown in Figure 6, the temperature of holding-zone should control at 960 ~ 980 DEG C, the temperature of rapid cooling section should control at 700 ~ 730 DEG C, the temperature of slow cooling section should control at 560 ~ 680 DEG C, in actual mechanical process, heating zone front end arranges preheating section, the body temperature of the cast iron pipe of annealing furnace is entered for preheating, to ensure the uniform heating of body, the rear and front end of slow cooling section adopts induced draft fan 6 to carry out temperature control operation respectively, be positioned at the induced draft fan 6 of front end, slow cooling section while control cast iron pipe body temperature, can also ensure that eutectoid transformation ferrite generates, slow cooling section adopts induced draft fan 6 to control the tapping temperature of cast iron pipe equally.
Embodiment 8:
The present embodiment relates to the preparation of the centrifugal ductile cast iron pipes of DN80mm, and step is as follows:
(A) use blast furnace or cupola furnace carry out pyrotic smelting to the pig iron, and acquisition sulphur content is 0.015%, carbon equivalent undulating quantity is the molten iron of 0.1%.
(B) nodularization method is poured in employing, first, nodulizing agent and nucleating agent is added successively in the groove 5 of nodularization bag 3, electricity consumption is made to help flatcar 4 nodularization bag 3 to be sent into the anti-room 2 of nodularization, then nodularization wire drive feeder 1 is aimed at the nodularization bag dykes and dams side not adding nodulizing agent to tap a blast furnace, in the present embodiment, nodularization wire drive feeder 1 goes out 1/3 place of iron to nodularization bag height with 35kg/s, pause 5s, then iron is measured to wrapping completely with tapping a blast furnace of 120kg/s, obtaining carbon equivalent undulating quantity is the spheroidization molten iron of 0.03%, by weight percentage, through nodularization, the hot metal ladle breeding rear acquisition contains: carbon 3.5%, sulphur 0.09%, silicon 2.36%, phosphorus 0.06%, magnesium 0.035%, manganese 0.34%, rhenium 0.025%, wherein, nodulizing agent is rare earth Mg-Si nodularizer, by weight percentage, rare earth 18 % is included in this rare earth Mg-Si nodularizer, magnesium 22%, silicon 48%, nucleating agent is ferrosilicon or silicocalcium, by weight percentage, includes silicon 48%, calcium 1.2% in this nucleating agent.
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, pipe die can adopt high temperature steel to be made, the temperature of main frame water coolant is 88 DEG C, by weight percentage, the pipe die powder that the present embodiment relates to includes the barium of 8%, 1% calcium, the silicon of 62%, its granularity is for being 0.25mm, the internal surface area of pressing pipe die calculates, the add-on of this pipe die powder is 25g/m
2, certainly, this pipe die powder also can be used for pipe die internal surface, after the internal surface spray of pipe die adds pipe die powder, then is extracted from pipe die by the cast iron casting pipe after shaping with drawbench.
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, and carry out anneal through the heating zone of annealing furnace, holding-zone, rapid cooling section and slow cooling section successively, wherein, the length of heating zone is 14m, the length of holding-zone is 9m, the length of rapid cooling section is 5m, the length of slow cooling section is 16m, when carrying out anneal, keep the temperature of holding-zone control 960 DEG C, the temperature of rapid cooling section control 700 DEG C, the temperature of slow cooling section controls at 560 DEG C; Meanwhile, suitably adjust the time of cast iron pipe by each temperature section according to the size of cast iron pipe caliber, in the present embodiment, cast iron pipe is 40min by the set of time of annealing furnace, to ensure the specification of quality of cast iron pipe products formed.
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe, wherein, impression adopts steel ball ball to carry out impression in the position at the socket inwall 40mm place of cast iron casting pipe, pressure is 6MPa, and after impression, cast iron casting pipe does not occur crackle; Reconditioning adopts air grinder to carry out reconditioning to cast iron pipe bell and spigot, adopts grinding-wheel grinder pole pair cast iron pipe inner wall to carry out reconditioning; Mark garden and campus adopt ring gauge to carry out mark garden and campus to cast iron casting pipe; Cut ring be adopt cut ring sampling to batch cast iron pipe carry out metallographic and performance checking.
(F) exterior protection cast iron pipe outer wall carried out by spray zinc, pitch spraying successively and inwall protection cast iron pipe carried out by cement coated lining, wherein, spray zinc be use spray gun that zinc is heated to molten state and the outer wall being ejected into cast iron pipe with droplets to form spelter coating, wherein, the quantity for spray of spelter coating is 130g/m
2; Pitch spraying adopts spraying, roller coating or brush to be coated in bituminous composition to form pitch tectum outside cast iron pipe spelter coating, and the thickness of brea bed is 70 μm, by weight percentage, and the solid content 60% of bituminous composition; Cement lining carries out coated with formation cement lining layer at cast iron pipe inner wall after fine sand, cement, 801 glue are carried out spice by proportioning, and the thickness of cement coated lining is 8 mm, with mass ratio range, and fine sand: cement: 801 glue=2:1.2:0.12.
After having sprayed, to the health that external protection coating in cast iron pipe carries out, step is as follows:
(F.a) the cast iron pipe natural Health preservation after spray zinc, pitch spraying, cement lining process was sent into health stove after 8 minutes, under adopting the condition of vapor pressure 0.15MPa, health temperature 33 DEG C, humidity 85%, health is carried out to cast iron pipe, conditioned time 8.5 hours;
(F.b) the cast iron pipe internal surface spraying epoxy ceramic coating after completing health, at its outside surface spray epoxy or polyurethane material.
Embodiment 9:
The present embodiment relates to the preparation of the centrifugal ductile cast iron pipes of 1000mm, and step is as follows:
(A) use blast furnace or cupola furnace carry out pyrotic smelting to the pig iron, and acquisition sulphur content is 0.02%, carbon equivalent undulating quantity is the molten iron of 0.08%.
(B) nodularization method is poured in employing, first, nodulizing agent and nucleating agent is added successively in the groove 5 of nodularization bag 3, electricity consumption is made to help flatcar 4 nodularization bag 3 to be sent into the anti-room 2 of nodularization, then nodularization wire drive feeder 1 is aimed at the nodularization bag dykes and dams side not adding nodulizing agent to tap a blast furnace, in the present embodiment, nodularization wire drive feeder 1 goes out 1/3 place of iron to nodularization bag height with 30kg/s, pause 4s, then iron is measured to wrapping completely with tapping a blast furnace of 100kg/s, obtaining carbon equivalent undulating quantity is the spheroidization molten iron of 0.032%, by weight percentage, through nodularization, the hot metal ladle breeding rear acquisition contains: carbon 3.3%, sulphur 0.09%, silicon 2.36%, phosphorus 0.07%, magnesium 0.035%, manganese 0.3%, rhenium 0.02%, wherein, nodulizing agent is rare earth Mg-Si nodularizer, by weight percentage, rare earth 18% is included in this rare earth Mg-Si nodularizer, magnesium 25%, silicon 49%, nucleating agent is ferrosilicon or silicocalcium, by weight percentage, includes silicon 50%, calcium 1.5 % in this nucleating agent.
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, pipe die can adopt high temperature steel to be made, the temperature of main frame water coolant is 90 DEG C, by weight percentage, the pipe die powder that the present embodiment relates to includes the barium of 8%, 2% calcium, the silicon of 65%, its granularity is 0.3mm, the internal surface area of pressing pipe die calculates, the add-on of this pipe die powder is 28g/m
2, certainly, this pipe die powder also can be used for pipe die internal surface, after the internal surface spray of pipe die adds pipe die powder, then is extracted from pipe die by the cast iron casting pipe after shaping with drawbench.
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, and carry out anneal through the heating zone of annealing furnace, holding-zone, rapid cooling section and slow cooling section successively, wherein, the length of heating zone is 13.45m, the length of holding-zone is 9m, the length of rapid cooling section is 4.5m, the length of slow cooling section is 15.2m, when carrying out anneal, keep the temperature of holding-zone control 960 DEG C, the temperature of rapid cooling section control 700 DEG C, the temperature of slow cooling section controls at 560 DEG C; Meanwhile, suitably adjust the time of cast iron pipe by each temperature section according to the size of cast iron pipe caliber, in the present embodiment, cast iron pipe is 60min by the set of time of annealing furnace, to ensure the specification of quality of cast iron pipe products formed.
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe, wherein, impression adopts steel ball ball to carry out impression in the position at the socket inwall 30mm place of cast iron casting pipe, pressure is 5MPa, and after impression, cast iron casting pipe does not occur crackle; Reconditioning adopts air grinder to carry out reconditioning to cast iron pipe bell and spigot, adopts grinding-wheel grinder pole pair cast iron pipe inner wall to carry out reconditioning; Mark garden and campus adopt ring gauge to carry out mark garden and campus to cast iron casting pipe; Cut ring be adopt cut ring sampling to batch cast iron pipe carry out metallographic and performance checking.
(F) exterior protection cast iron pipe outer wall carried out by spray zinc, pitch spraying successively and inwall protection cast iron pipe carried out by cement coated lining, wherein, spray zinc be use spray gun that zinc is heated to molten state and the outer wall being ejected into cast iron pipe with droplets to form spelter coating, wherein, the quantity for spray of spelter coating is 120g/m
2; Pitch spraying adopts spraying, roller coating or brush to be coated in bituminous composition to form pitch tectum outside cast iron pipe spelter coating, and the thickness of brea bed is 60 μm, by weight percentage, and the solid content 60% of bituminous composition; Cement lining carries out coated with formation cement lining layer at cast iron pipe inner wall after fine sand, cement, 801 glue are carried out spice by proportioning, and the thickness of cement coated lining is 3 ~ 8 mm, with mass ratio range, and fine sand: cement: 801 glue=2:1.5:0.15.
After having sprayed, to the health that external protection coating in cast iron pipe carries out, step is as follows:
(F.a) the cast iron pipe natural Health preservation after spray zinc, pitch spraying, cement lining process was sent into health stove after 12 minutes, under adopting the condition of vapor pressure 0.15MPa, health temperature 50 DEG C, humidity 90%, health is carried out to cast iron pipe, conditioned time 10 hours;
(F.b) the cast iron pipe internal surface spraying epoxy ceramic coating after completing health, at its outside surface spray epoxy or polyurethane material.
Embodiment 10:
The present embodiment relates to the preparation of the centrifugal ductile cast iron pipes of DN800mm, and step is as follows:
(A) use blast furnace or cupola furnace carry out pyrotic smelting to the pig iron, and acquisition sulphur content is 0.02%, carbon equivalent undulating quantity is the molten iron of 0.1%.
(B) nodularization method is poured in employing, first, nodulizing agent and nucleating agent is added successively in the groove 5 of nodularization bag 3, electricity consumption is made to help flatcar 4 nodularization bag 3 to be sent into the anti-room 2 of nodularization, then nodularization wire drive feeder 1 is aimed at the nodularization bag dykes and dams side not adding nodulizing agent to tap a blast furnace, in the present embodiment, nodularization wire drive feeder 1 goes out 1/2 place of iron to nodularization bag height with 30kg/s, pause 3s, then iron is measured to wrapping completely with tapping a blast furnace of 110kg/s, obtaining carbon equivalent undulating quantity is the spheroidization molten iron of 0.032%, by weight percentage, through nodularization, the hot metal ladle breeding rear acquisition contains: carbon 3.5%, sulphur 0.08%, silicon 2.35%, phosphorus 0.065%, magnesium 0.035%, manganese 0.28%, rhenium 0.025%, wherein, nodulizing agent is rare earth Mg-Si nodularizer, by weight percentage, rare earth 20 % is included in this rare earth Mg-Si nodularizer, magnesium 20%, silicon 50%, nucleating agent is ferrosilicon or silicocalcium, by weight percentage, includes silicon 50%, calcium 1.4% in this nucleating agent.
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, pipe die can adopt high temperature steel to be made, the temperature of main frame water coolant is 95 DEG C, by weight percentage, the pipe die powder that the present embodiment relates to includes the barium of 8%, 1.8% calcium, the silicon of 64%, its granularity is 0.25mm, the internal surface area of pressing pipe die calculates, the add-on of this pipe die powder is 25g/m
2, certainly, this pipe die powder also can be used for pipe die internal surface, after the internal surface spray of pipe die adds pipe die powder, then is extracted from pipe die by the cast iron casting pipe after shaping with drawbench.
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, and carry out anneal through the heating zone of annealing furnace, holding-zone, rapid cooling section and slow cooling section successively, wherein, the length of heating zone is 13.5m, the length of holding-zone is 8.5m, the length of rapid cooling section is 4.2m, the length of slow cooling section is 15.6m, when carrying out anneal, keep the temperature of holding-zone control 970 DEG C, the temperature of rapid cooling section control 720 DEG C, the temperature of slow cooling section controls at 600 DEG C; Meanwhile, suitably adjust the time of cast iron pipe by each temperature section according to the size of cast iron pipe caliber, in the present embodiment, cast iron pipe is 55min by the set of time of annealing furnace, to ensure the specification of quality of cast iron pipe products formed.
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe, wherein, impression adopts steel ball ball to carry out impression in the position at the socket inwall 26mm place of cast iron casting pipe, pressure is 4.5MPa, and after impression, cast iron casting pipe does not occur crackle; Reconditioning adopts air grinder to carry out reconditioning to cast iron pipe bell and spigot, adopts grinding-wheel grinder pole pair cast iron pipe inner wall to carry out reconditioning; Mark garden and campus adopt ring gauge to carry out mark garden and campus to cast iron casting pipe; Cut ring be adopt cut ring sampling to batch cast iron pipe carry out metallographic and performance checking.
(F) exterior protection cast iron pipe outer wall carried out by spray zinc, pitch spraying successively and inwall protection cast iron pipe carried out by cement coated lining, wherein, spray zinc be use spray gun that zinc is heated to molten state and the outer wall being ejected into cast iron pipe with droplets to form spelter coating, wherein, the quantity for spray of spelter coating is 120g/m
2; Pitch spraying adopts spraying, roller coating or brush to be coated in bituminous composition to form pitch tectum outside cast iron pipe spelter coating, and the thickness of brea bed is 55 μm, by weight percentage, and the solid content 60% of bituminous composition; Cement lining carries out coated with formation cement lining layer at cast iron pipe inner wall after fine sand, cement, 801 glue are carried out spice by proportioning, and the thickness of cement coated lining is 3 ~ 8 mm, with mass ratio range, and fine sand: cement: 801 glue=2:1.3:0.14.
After having sprayed, to the health that external protection coating in cast iron pipe carries out, step is as follows:
(F.a) the cast iron pipe natural Health preservation after spray zinc, pitch spraying, cement lining process was sent into health stove after 10 minutes, health is carried out to cast iron pipe, conditioned time > 8 hours under adopting the condition of vapor pressure 0.2MPa, health temperature 45 DEG C, humidity 85%;
(F.b) the cast iron pipe internal surface spraying epoxy ceramic coating after completing health, at its outside surface spray epoxy or polyurethane material.
Embodiment 11:
The present embodiment relates to the preparation of the centrifugal ductile cast iron pipes of DN600mm, and step is as follows:
(A) use blast furnace or cupola furnace carry out pyrotic smelting to the pig iron, and acquisition sulphur content is 0.02%, carbon equivalent undulating quantity is the molten iron of 0.05%.
(B) nodularization method is poured in employing, first, nodulizing agent and nucleating agent is added successively in the groove 5 of nodularization bag 3, electricity consumption is made to help flatcar 4 nodularization bag 3 to be sent into the anti-room 2 of nodularization, then nodularization wire drive feeder 1 is aimed at the nodularization bag dykes and dams side not adding nodulizing agent to tap a blast furnace, in the present embodiment, nodularization wire drive feeder 1 goes out 1/2 place of iron to nodularization bag height with 25kg/s, pause 5s, then iron is measured to wrapping completely with tapping a blast furnace of 120kg/s, obtaining carbon equivalent undulating quantity is the spheroidization molten iron of 0.032%, by weight percentage, through nodularization, the hot metal ladle breeding rear acquisition contains: carbon 3.3%, sulphur 0.008%, silicon 2.33%, phosphorus 0.07%, magnesium 0.035%, manganese 0.32%, rhenium 0.025%, wherein, nodulizing agent is rare earth Mg-Si nodularizer, by weight percentage, rare earth 19% is included in this rare earth Mg-Si nodularizer, magnesium 22%, silicon 48%, nucleating agent is ferrosilicon or silicocalcium, by weight percentage, includes silicon 46%, calcium 1.5 % in this nucleating agent.
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, pipe die can adopt high temperature steel to be made, the temperature of main frame water coolant is 96 DEG C, by weight percentage, the pipe die powder that the present embodiment relates to includes the barium of 12%, 1% calcium, the silicon of 64%, its granularity is 0.3mm, the internal surface area of pressing pipe die calculates, the add-on of this pipe die powder is 28g/m
2, certainly, this pipe die powder also can be used for pipe die internal surface, after the internal surface spray of pipe die adds pipe die powder, then is extracted from pipe die by the cast iron casting pipe after shaping with drawbench.
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, and carry out anneal through the heating zone of annealing furnace, holding-zone, rapid cooling section and slow cooling section successively, wherein, the length of heating zone is 13.6m, the length of holding-zone is 8.7m, the length of rapid cooling section is 4.5m, the length of slow cooling section is 15.2m, when carrying out anneal, keep the temperature of holding-zone control 980 DEG C, the temperature of rapid cooling section control 720 DEG C, the temperature of slow cooling section controls at 650 DEG C; Meanwhile, suitably adjust the time of cast iron pipe by each temperature section according to the size of cast iron pipe caliber, in the present embodiment, cast iron pipe is 55min by the set of time of annealing furnace, to ensure the specification of quality of cast iron pipe products formed.
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe, wherein, impression adopts steel ball ball to carry out impression in the position at the socket inwall 25mm place of cast iron casting pipe, pressure is 5MPa, and after impression, cast iron casting pipe does not occur crackle; Reconditioning adopts air grinder to carry out reconditioning to cast iron pipe bell and spigot, adopts grinding-wheel grinder pole pair cast iron pipe inner wall to carry out reconditioning; Mark garden and campus adopt ring gauge to carry out mark garden and campus to cast iron casting pipe; Cut ring be adopt cut ring sampling to batch cast iron pipe carry out metallographic and performance checking.
(F) exterior protection cast iron pipe outer wall carried out by spray zinc, pitch spraying successively and inwall protection cast iron pipe carried out by cement coated lining, wherein, spray zinc be use spray gun that zinc is heated to molten state and the outer wall being ejected into cast iron pipe with droplets to form spelter coating, wherein, the quantity for spray of spelter coating is 120g/m
2; Pitch spraying adopts spraying, roller coating or brush to be coated in bituminous composition to form pitch tectum outside cast iron pipe spelter coating, and the thickness of brea bed is 60 μm, by weight percentage, and the solid content 60% of bituminous composition; Cement lining carries out coated with formation cement lining layer at cast iron pipe inner wall after fine sand, cement, 801 glue are carried out spice by proportioning, and the thickness of cement coated lining is 6 mm, with mass ratio range, and fine sand: cement: 801 glue=2:1.4:0.13.
After having sprayed, to the health that external protection coating in cast iron pipe carries out, step is as follows:
(F.a) the cast iron pipe natural Health preservation after spray zinc, pitch spraying, cement lining process was sent into health stove after 12 minutes, under adopting the condition of vapor pressure 0.22MPa, health temperature 45 DEG C, humidity 92%, health is carried out to cast iron pipe, conditioned time 10 hours;
(F.b) the cast iron pipe internal surface spraying epoxy ceramic coating after completing health, at its outside surface spray epoxy or polyurethane material.
Prepare cast iron pipe to above-described embodiment 1 ~ 11 to detect, obtain data shown in table 1.
Table 1
The above is only preferred embodiment of the present invention, and not do any pro forma restriction to the present invention, every any simple modification, equivalent variations done above embodiment according to technical spirit of the present invention, all falls within protection scope of the present invention.
Claims (10)
1. a preparation method for centrifugal ductile cast iron pipes, is characterized in that: preparation process is as follows:
(A) use blast furnace or cupola furnace to carry out pyrotic smelting to the pig iron, obtain the molten iron of sulphur content≤0.02%, carbon equivalent undulating quantity≤± 0.1%;
(B) molten iron obtained for step (A) is sent into nodularization station, by the nodularization wire drive feeder (1) at nodularization station, molten iron is carried out spheroidizing to entering nodularization bag (3), the hot metal ladle obtained after nodularization contains: carbon 3.2 ~ 3.5%, sulphur < 0.01%, silicon 2.3 ~ 2.36%, phosphorus < 0.073%, magnesium >=0.035%, manganese < 0.35%, rhenium < 0.026%, before entering molten iron, nodulizing agent and nucleating agent is added successively in nodularization bag (3), described nodulizing agent is rare earth Mg-Si nodularizer, by weight percentage, rare earth 18 ~ 20 % is included in described rare earth Mg-Si nodularizer, magnesium 20 ~ 25%, silicon 46 ~ 50, described nucleating agent is ferrosilicon or silicocalcium, by weight percentage, includes silicon 46 ~ 50%, calcium 1.2 ~ 1.5 % in described nucleating agent,
(C) with overhead traveling crane by molten iron obtained for step (B) respectively to entering tundish and fan-shaped bag, use package turning mechanism that the molten iron constant speed in tundish and fan-shaped bag is ploughed under chute, again the molten iron flowing into chute is sent into pipe die, rotate in pipe die and pass through main frame water coolant shaping after, obtain cast iron casting pipe, and with drawbench, the cast iron casting pipe after shaping is extracted from pipe die;
(D) cast iron pipe obtained for step (C) is sent into annealing furnace, annealing furnace is sent successively after heating, insulation, rapid cooling, slow cooling, the time controlling cast iron pipe annealed stove is 40 ~ 60min, the cast iron pipe sending annealing furnace after air cooling as cast iron pipe products formed;
(E) the cast iron pipe products formed obtained step (D) uses impression, mark garden and campus successively, cuts ring, reconditioning and hydraulic pressure test, to complete the integer process of cast iron pipe;
(F) carry out exterior protection to the cast iron pipe outer wall after integer process, comprise successively to spray zinc and the pitch spraying of the enforcement of cast iron pipe outer wall, the thickness of described zinc layers is 110 ~ 130g/m
2, the thickness of described brea bed is 50 ~ 70 μm; Carry out inwall protection to the cast iron pipe inner wall after integer process, comprise the cement coated lining implemented cast iron pipe inner wall, the thickness of described cement coated lining is 3 ~ 8 mm.
2. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 1, it is characterized in that: the bottom of described nodularization bag (3) and the side of nodularization bag dykes and dams form the groove (5) holding nodulizing agent and nucleating agent, and described molten iron is tapped a blast furnace along the nodularization bag dykes and dams not forming groove (5) side by nodularization wire drive feeder (1).
3. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 1, it is characterized in that: described nodularization wire drive feeder (1) taps a blast furnace with the iron that goes out of 25 ~ 35kg/s, tap a blast furnace to 1/2 ~ 1/3 place of nodularization bag height, pause 3 ~ 5s, then iron is measured to wrapping completely with tapping a blast furnace of 80 ~ 120kg/s, the hot metal ladle obtained after nodularization contains the magnesium of 0.035%, its carbon equivalent undulating quantity≤0.032%.
4. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 1, it is characterized in that: in described step (C), after on the internal surface of pipe die, spray adds pipe die powder, again the molten iron flowing into chute is sent into pipe die, described pipe die is that high temperature steel is made, the temperature < of described main frame water coolant 100 DEG C.
5. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 1, is characterized in that: in described step (C), before being extracted by the cast iron casting pipe after shaping, adds pipe die powder in the internal surface spray of pipe die with drawbench from pipe die.
6. the preparation method of a kind of centrifugal ductile cast iron pipes according to any one of claim 4 or 5, it is characterized in that: by weight percentage, described pipe die powder include 6 ~ 12% barium, 1 ~ 2% calcium, 60 ~ 65% silicon, its granularity≤0.3mm, calculate by the internal surface area of described pipe die, the add-on of described pipe die powder is 20 ~ 30g/m
2.
7. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 1, it is characterized in that: in described step (F), described spray zinc be use spray gun that zinc is heated to molten state and the outer wall being ejected into cast iron pipe with droplets to form spelter coating, the quantity for spray of described spelter coating is 120g/m
2.
8. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 7, it is characterized in that: in described step (F), described pitch spraying adopts spraying, roller coating or brush to be coated in outside cast iron pipe spelter coating bituminous composition to form pitch tectum, by weight percentage, solid content≤65% of described bituminous composition.
9. the preparation method of a kind of centrifugal ductile cast iron pipes according to claim 8, it is characterized in that: in described step (F), described cement lining carries out coated with formation cement lining layer at cast iron pipe inner wall after fine sand, cement, 801 glue are carried out spice by proportioning, with mass ratio range, described fine sand: cement: 801 glue=2:(1.2 ~ 1.5): (0.12 ~ 0.15).
10. the preparation method of a kind of centrifugal ductile cast iron pipes according to any one of claim 7 ~ 9, is characterized in that: in described step (F), described coating processes also comprises the health carried out external protection coating in cast iron pipe, and step is as follows:
(F.a) the cast iron pipe natural Health preservation after spray zinc, pitch spraying, cement lining process was sent into health stove after 5 ~ 15 minutes, health is carried out to cast iron pipe, conditioned time > 8 hours under adopting the condition of vapor pressure >=0.15MPa, health temperature > 30 DEG C, humidity >=85%;
(F.b) the cast iron pipe internal surface spraying epoxy ceramic coating after completing health, at its outside surface spray epoxy or polyurethane material.
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| CN106647678A (en) * | 2017-02-04 | 2017-05-10 | 大连银冈科技发展有限公司 | Spheroidal graphite cast iron tube production process tracking method and data acquisition system |
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| WO2019201179A1 (en) * | 2018-04-20 | 2019-10-24 | 广东北晟益通实业有限公司 | Spheroidal graphite cast iron pipe, preparation process of spheroidal graphite cast iron pipe for urban high-pressure gas pipeline, and spheroidal graphite cast iron pipe for urban high-pressure gas pipeline |
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| CN112410496A (en) * | 2020-11-23 | 2021-02-26 | 广东新兴铸管有限公司 | Efficient centrifugal production process method for nodular cast iron pipe |
| CN113005355A (en) * | 2021-02-25 | 2021-06-22 | 安阳钢铁股份有限公司 | Production process of nodular cast iron pipe pile |
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| CN113005355A (en) * | 2021-02-25 | 2021-06-22 | 安阳钢铁股份有限公司 | Production process of nodular cast iron pipe pile |
| CN114101619A (en) * | 2021-11-30 | 2022-03-01 | 国铭铸管股份有限公司 | Centrifugal casting process of nodular cast pipe |
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