Vertical metal powder continuous fritting furnace
Technical field
The present invention relates to a kind of vertical metal powder continuous fritting furnace, the particularly a kind of vertical metal powder continuous fritting furnace that can realize continuous, quick alloying technology in powder metallurgy, hard material field to metal mixed material particle.
Technical background
The application of hard material in Surface Engineering is through thermal process technology such as thermal sprayings it to be coated in metal or surface of the work, thereby improves surface abrasion resistance damage, shock resistance, performance such as high temperature resistant, corrosion-resistant, significant prolongation workpiece service life; Also can repair waste and old workpiece, reinforcement, make its recovery or surpass original serviceability, thereby practice thrift a large amount of metal materials and production cost.Therefore the extensive use of hard material is to promoting sustainable economic development, and constructing economical society has important practical significance and far-reaching strategic importance.The thermal spraying metal dust is the hard material that a kind of consumption is maximum, purposes is the widest, also is one of strategic basic material that supports China's modern industry and modern national defense.
Compound powder or the alloy material powder all formed as the thermal spraying metal dust overwhelming majority of hard material by two or more metal materials; Be divided into low form and high temperature modification two big classes by sintering temperature; The low form powder is a kind of multiple metal (or metal+alloy) powder to be tied the compound powder (or composite powder) that obtains with binder low temperature presintering below mixing wet-milling granulations-ungrease treatment-800 ℃; It is multiple metal (or metal+alloy) the powder mixes set of formed particle together (hereinafter to be referred as the compound powder); The combination of compound powder granule interior is a kind of mechanical bond, and granule strength is low, packing is low, apparent density is little; The high temperature modification powder is the alloying powder that low form compound powder is obtained behind high temperature sintering; Alloy powder transfers the adhesion of granule interior to metallurgical binding by mechanical bond; Powder particle intensity, packing and apparent density have been improved; So alloying spraying powder is a kind of high performance hard material.
High temperature sintering is one of key technology of producing alloyed powder, also is the bottleneck technology of the high-quality alloyed powder large-scale production of serious restriction China at present.Traditional alloyed powder preparation technology is: the compound powder is placed on reaches several hours heat in the container, obtain through break process after the cooling again.This traditional handicraft cause powder grain significantly to be grown up, and grain growth will directly influence the anti-wear performance of sprayed coating because heat time heating time is long; On the other hand; Because powder accumulation concentrates heating to cause powder agglomates in container; Must carry out break process, and fragmentation causes powder size skewness, granule-morphology to change, and produces a large amount of oversizes and screenings simultaneously and causes the product casting yield low.
Summary of the invention
The objective of the invention is to overcome above-mentioned high-sintering process defective, provide a kind of crystallite dimension relatively stable, can optimize that granule-morphology and performance, casting yield and apparent density are all high, technological process is short, production cost is low, be fit to the vertical metal powder continuous fritting furnace of industrial-scale production.
Technical scheme of the present invention: a kind of vertical metal powder continuous fritting furnace; Comprise air inlet pipe, conveying pipeline, heat-insulation layer, tremie pipe, bell, circular heat-generating pipe, heating cylindrical shell, induction heater, cooling cylindrical shell; Circular heat-generating pipe places heating cylindrical shell center; The heat-generating pipe periphery is provided with tubular type heat-insulation layer and induction heater successively, and corresponding induction heater height position is the thermal treatment zone between the interior cylindrical zone of heat-generating pipe, it is characterized in that:
Described tremie pipe is the water-cooled tremie pipe of flanged (FLGD) cylindrical interlayer water flowing structure; This tremie pipe is fixed on the bell center flange; The centre bore outlet of tremie pipe is stretched in the heat-generating pipe and near position, the thermal treatment zone; The periphery of tremie pipe flange below and bottom end face are with the step heat-insulation layer to coat, and the centre bore of tremie pipe is a blanking channel;
Described band step heat-insulation layer is supported on the upper surface of circular heat-generating pipe through its step; Band step heat-insulation layer upper end is stretched in the bell center flange cover; The lower end is stretched in the heat-generating pipe and near position, the thermal treatment zone, and the center-hole diameter of band step heat-insulation layer bottom is greater than the outlet diameter of the centre bore of tremie pipe;
Be provided with cooling water pipe in the described tremie pipe interlayer; One side ports extend near the interlayer bottom position this cooling water pipe from tremie pipe top; Tremie pipe centre bore upper end is provided with the center surveillance mirror; Tremie pipe top one side is provided with conveying pipeline, and this conveying pipeline gets into from the side with the centre bore of tremie pipe and communicates;
Described bell is provided with the peephole of band surveillance mirror, and this peephole original position is to pass water-cooled tremie pipe flange, bell center flange and band step heat-insulation layer successively;
The another kind of form of the centre bore pelvic outlet plane position of described tremie pipe, this pelvic outlet plane are higher than or put down the upper surface in circular heat-generating pipe, and under this form, the cooling medium in the tremie pipe interlayer can be a water, also can be gas.
This vertical metal powder continuous fritting furnace, overall structure are vertical structure, and sintering furnace comprises bell, heating cylindrical shell, the cooling cylindrical shell that the water-cooled tremie pipe is housed, and the three is stacked with one heart from top to bottom.Circular heat-generating pipe places heating cylindrical shell center, and the heat-generating pipe periphery is provided with heat-insulation layer and induction heater successively, and corresponding inductor height position is the thermal treatment zone between the interior cylindrical zone of heat-generating pipe; Heating cylindrical shell top is provided with bell, and the bell center is provided with the water-cooled tremie pipe; The cooling cylindrical shell is the through-hole type cylinder of band circular cone.Nitrogen or argon gas get into the tremie pipe centre bore and are heated metal dust and mix from air inlet pipe, and order gets into the thermal treatment zone, cooling zone, and the powder that companion sinters discharges out of the furnace from cooling off cylindrical shell bottom discharge mouth.
The production work of this vertical metal powder continuous fritting furnace is made as continuously-running duty; Maximum operation (service) temperature is 2200 ℃; Mode of heating is an eddy-current heating; Be mainly used in the compound metal dust is carried out sintering rapidly, continuously, to obtain crystallite dimension and the metastable high-quality metal of alloying powder of granule-morphology.Sintering furnace is by charging, heating, cooling three parts of arranged concentric are formed from top to bottom.That feeding part is responsible for is controlled, to the thermal treatment zone powder is provided equably; Heating part is responsible for the compound powder is heated rapidly to technological temperature and realizes alloying technology, makes compound become alloyed powder; Cooling segment is responsible for alloyed powder is cooled off fast and sees off outside the stove.
Innovative point of the present invention is: reduce tremie pipe centre bore temperature through adopting water-cooling pattern; Particularly reduce tremie pipe centre bore outlet at bottom temperature; Preventing effectively that powder is bonded on the tremie pipe inwall stops up centre bore and causes the metal dust blanking to be obstructed; Experiment showed, if tremie pipe centre bore temperature is too high, only need several hrs even dozens of minutes tremie pipe to stop up; On the other hand; The tremie pipe discharging opening is stretched into the heat-generating pipe endoporus and near the thermal treatment zone, shortened discharging opening to the distance between the thermal treatment zone, can significantly reduce powder and descend slowly and lightly and be bonded at the ratio on the heat-generating pipe inwall; Improve the product casting yield, prolong sintering furnace stream time and service life.
Production process: add protective gas from the air inlet pipe of top, the thermal treatment zone and the air inlet pipe of below, the thermal treatment zone respectively; Air in the body of heater is discharged out of the furnace, after oxygen content is lower than process value in the affirmation stove, send to body of heater; The thermal treatment zone in the heat-generating pipe begins to heat up; After temperature arrives process value, by feeding mechanism that the compound powder of certain particle size scope is controlled through conveying pipeline, add water-cooled tremie pipe centre bore equably, get into the thermal treatment zone; And fall with the freely falling body mode; In dropping process, be rapidly heated to technological temperature and accomplish alloying technology process (or sintering process), continue to drop to the cooling cylindrical shell of below, the thermal treatment zone then, cool off after cooling cylindrical shell bottom discharge pipe is fallen outside the stove through the thermal treatment zone.Material is controlled by feeding mechanism, continuously, evenly, controllably passes through tremie pipe, the thermal treatment zone, cooling zone and discharge nozzle in proper order, has realized continuous production processes.
Description of drawings
Fig. 1 is the structural representation of this sintering furnace;
The WC-12Co alloy powder stereoscan photograph (100X) that Fig. 2 produces for this sintering furnace;
The WC-12Co alloy powder stereoscan photograph (5000X) that Fig. 3 produces for this sintering furnace;
Among the figure: 1-peephole, 2-bell center flange, 3-cooling water pipe, 4-air inlet pipe, 5-center surveillance mirror; The 6-conveying pipeline, 7-band step heat-insulation layer, 8-tremie pipe, 9-bell; 10-tremie pipe centre bore, the 11-heat-generating pipe, 12-heats cylindrical shell, the 13-thermal treatment zone; 14-tubular type heat-insulation layer, the 15-induction heater, 16-cools off cylindrical shell, 17-air inlet pipe.
The specific embodiment:
Referring to Fig. 1; A kind of vertical metal powder continuous fritting furnace; Comprise air inlet pipe, conveying pipeline 6, heat-insulation layer, tremie pipe 8, bell 9, circular heat-generating pipe 11, heating cylindrical shell 12, induction heater 15, cooling cylindrical shell 16, circular heat-generating pipe 11 places heating cylindrical shell 12 centers, and heat-generating pipe 11 peripheries are provided with tubular type heat-insulation layer 14 and induction heater 15 successively; Corresponding induction heater 15 height positions are the thermal treatment zone 13 between heat-generating pipe 11 interior cylindrical zone, it is characterized in that:
Described tremie pipe 8 is the water-cooled tremie pipe of flanged (FLGD) cylindrical interlayer water flowing structure; This tremie pipe 8 is fixed on the bell center flange 2; The outlet of the centre bore 10 of tremie pipe 8 is stretched in the heat-generating pipe 11 and near 13 positions, the thermal treatment zone; The periphery of tremie pipe 8 flanges below and bottom end face are with step heat-insulation layer 7 to coat, and the centre bore 10 of tremie pipe 8 is a blanking channel;
Described band step heat-insulation layer 7 is supported on the upper surface of circular heat-generating pipe 11 through its step; Band step heat-insulation layer 7 upper ends are stretched in the bell center flange cover; The lower end is stretched in the heat-generating pipe 11 and near 13 positions, the thermal treatment zone, and the center-hole diameter of band step heat-insulation layer 7 bottoms is greater than the outlet diameter of the centre bore 10 of tremie pipe 8;
Be provided with cooling water pipe 3 in described tremie pipe 8 interlayers; One side ports extend near the interlayer bottom position this cooling water pipe 3 from tremie pipe 8 tops; Tremie pipe 8 centre bores 10 upper ends are provided with center surveillance mirror 5; Tremie pipe 8 tops one side is provided with conveying pipeline 6, and this conveying pipeline 6 gets into from the side with the centre bore 10 of tremie pipe 8 and communicates;
Described bell is provided with the peephole 1 of band surveillance mirror, and this peephole 1 original position is to pass water-cooled tremie pipe flange, bell center flange 2 and band step heat-insulation layer 7 successively;
The another kind of form of the pelvic outlet plane position of the centre bore 10 of described tremie pipe 8, this pelvic outlet plane are higher than or put down in the upper surface of circular heat-generating pipe 11, and under this form, the cooling medium in tremie pipe 8 interlayers can be a water, also can be gas.
The bell that water-cooled tremie pipe 8 is housed 9 of this sintering furnace, heating cylindrical shell 12, cooling cylindrical shell 16, the three is stacked with one heart from top to bottom.The interval corresponding inductor of heat-generating pipe 11 center holes 15 height positions are the thermal treatment zone 13; Heating cylindrical shell top is provided with bell 9, and bell 9 centers are provided with water-cooled tremie pipe 8; Cooling cylindrical shell 16 through-hole type cylinders for the band circular cone.
Nitrogen or argon gas get into tremie pipes 8 centre bores and are heated metal dust and mix from air inlet pipe 4, and order gets into the thermal treatment zone, cooling zone, and the powder that companion sinters discharges out of the furnace from cooling off cylindrical shell bottom discharge mouth.
Production process: add protective gas from the air inlet pipe 4 of top, the thermal treatment zone and the air inlet pipe 17 of below, the thermal treatment zone respectively; Air in the body of heater is discharged out of the furnace, after oxygen content is lower than process value in the affirmation stove, send to body of heater; The thermal treatment zone 13 in the heat-generating pipe 11 begins to heat up; After temperature arrives process value, by feeding mechanism that the compound powder of certain particle size scope is 6 controlled through conveying pipeline, add the centre bore 10 of water-cooled tremie pipe 8 equably, get into the thermal treatment zone 13; And fall with the freely falling body mode; In dropping process, be rapidly heated to technological temperature and accomplish the alloying technology process, continue to drop to the cooling cylindrical shell 16 of 13 belows, the thermal treatment zone then, cool off after cooling cylindrical shell 16 bottom discharge pipes are fallen outside the stove through the thermal treatment zone 13.Material is controlled by feeding mechanism, continuously, evenly, controllably passes through tremie pipe, the thermal treatment zone, cooling zone and discharge nozzle in proper order, has realized continuous production processes.
WC-12Co (tungsten carbide-12 cobalt) the alloy powder stereoscan photograph that Fig. 2, Fig. 3 produce for this sintering furnace; Wherein Fig. 2 multiplication factor is 100 times, and Fig. 3 multiplication factor is 5000 times, and photo shows that this powder particle has produced liquid-phase sintering to a certain extent; The surface is closely knit smooth; Pattern more trends towards sphere, the broken phenomenon of not breaking basically, and those broken fine particles have all become sphere; Realized that the granule interior starting powder transfers metallurgical binding to by mechanical bond, formed sintered alloy powder with certain strength character.