CN101126146B - Chromizing method by using shaft furnace - Google Patents
Chromizing method by using shaft furnace Download PDFInfo
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- CN101126146B CN101126146B CN2007101318990A CN200710131899A CN101126146B CN 101126146 B CN101126146 B CN 101126146B CN 2007101318990 A CN2007101318990 A CN 2007101318990A CN 200710131899 A CN200710131899 A CN 200710131899A CN 101126146 B CN101126146 B CN 101126146B
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- chromising
- furnace
- pit furnace
- jar
- suspension bracket
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Abstract
The invention relates to a method applying vertical pit furnace as chromising device; at least two thermoelectric couples are arranged in the furnace to control the temperature in section with a temperature difference less than 5 centigrade. As the parts are placed evenly along the wall of the furnace, the temperature in the furnace is relative even and the heat transmission is in high efficiency, the size differences of the same parts are remarkably reduced after the chromising process; therefore, the usage precision demands of parts are ensured with a pass rate above 96 percent. The vertical pit furnace is equipped with a protective ring and a hanging bracket; the chromising jars are both carried in and out of the furnace with the bridge crane, avoiding the jar to collide the furnace wall and prolonging the life span of furnace, furnace cord and other parts. The power of the vertical pit furnace of the invention is 100kw; the chromising jars are placed in two layers in the furnace chromising 6 jars once, so that the work efficiency is increased at 1 to 2 folds. The invention can also be popularized in the parts process of other similar types.
Description
Technical field
The present invention is a kind of chromising method, is specially a kind of method of using the pit furnace chromising.
Background technology
In the industrial production, pack chromizing technology mainly is box-type furnace because of its chromising equipment at present, and its initial investment is less, can satisfy the small serial production requirement, still is being widely used.1 thermopair temperature control is generally used in existing box-type furnace chromising because the part tinning arranges vertically, before, during and after the temperature uniformity of position not good, cause the size of part of the same race after the chromising great fluctuation process scope that rises bigger.Because chromising atmosphere has stronger corrodibility, directly influences the heat preservation property of body of heater, the tank body volume is big more, and the problem of bringing is that the individual size difference between the chromising part is just big more in the chromising process, if defective, the cost of doing over again is just than higher.And the life-span of a box chromising stove have only 1～2 year, later maintenance cost is quite high.
Summary of the invention
The technical problem to be solved in the present invention is: the existing handicraft product quality of box-type furnace chromising of using is difficult for guaranteeing that production cost also increases thereupon, and the box-type furnace life-span is short, the maintenance cost height.
Technical scheme of the present invention is: a kind of method of using the pit furnace chromising, and adopt pit furnace as chromising equipment, described pit furnace uses at least 2 thermocouple temperature measurements, and thermopair is distributed on the sidewall by the high equal proportion of stove, and the chromising jar is evenly put along the furnace wall during chromising.
As improvement, the pit furnace inside that the present invention uses is equipped with guard circle, and guard circle and twere are every 30～40mm, and the guard circle main body uses 3 steel pipes to surround at least, and the top of guard circle is close to the furnace wall and is fixed.Guard circle can the chromising jar can not touched bosh brick body, stove silk during the lifting turnover.
Owing to use pit furnace, stove is high to be increased, and body of heater is provided with many thermopair temperature controls, and temperature is even in the stove, and the chromising jar can be put by the suspension bracket layering that sets, and improves to add heat transfer efficiencies.Be provided with 3-5 root supporting tube in the body of heater bottom, along the furnace wall uniform distribution, at least be provided with 1 lateral brace frame on the every supporting tube, the chromising jar is placed on and passes in and out pit furnace on the suspension bracket, the leaving certain gaps uncovered by the economic plan of suspension bracket loading surface, when loading the chromising jar and lifting into pit furnace, the notch alignment supporting tube of suspension bracket is fallen furnace bottom; When placing next suspension bracket, its loading surface breach and supporting tube are staggered, place on the lateral brace frame, the layering in pit furnace of chromising jar is placed.
The outer ring of suspension bracket loading surface also is provided with and keeps off the device of stumbling, and is used for preventing that hoisting process chromising jar from rocking or skidding off suspension bracket.
Chromising jar, pit furnace stove silk, guard circle, supporting tube, suspension bracket material are heat-resistance stainless steel among the present invention, as Cr
25Ni
20, under the high-temperature service environment life-time service oxidation less, be out of shape lessly, make these chromising equipment that be arranged long work-ing life.
The present invention adopts pit furnace to carry out chromising and handles, use 2-3 to prop up thermopair segmentation thermometric in stove, the Control for Kiln Temperature fluctuation is lower than 5 ℃, because the part tinning is evenly put along the furnace wall, temperature uniformity is better, heat transfer efficiency is higher, the size of part of the same race after the chromising great fluctuation process scope that rises obviously reduces, thereby has guaranteed the service precision requirement of part, and first-time qualification rate obviously rises, can reach more than 96%, this is that original technology is difficult to reach.The guard circle that pit furnace sets, suspension bracket with the driving integral hoisting, have been avoided the collision of tank body and furnace wall when making chromising jar turnover stove, have prolonged the work-ing life of parts such as body of heater, stove silk.From prolonged application, 85+10% kilowatt of the box-type furnace power of original technology, only 2～3 jars of chromisings at every turn, 100 kilowatts of the pit furnace power of the inventive method, divide 2 layers in the general stove and place the chromising jars, but 6 jars of each chromisings are increased work efficiency 1～2 times, can save the electricity charge 100 every year, more than 000 yuan,, effectively save direct production cost about 40 through about 6 months actual motion, 000 yuan, created favorable economic benefit.The present invention can also be generalized among the part processing of similar other close kind.
Description of drawings
Fig. 1 is the embodiment synoptic diagram of the pit furnace that uses of the present invention.
Fig. 2 is the guard circle and the bracing frame synoptic diagram of the embodiment of the invention 1
Fig. 3 is the vertical view of the embodiment of the invention 1 guard circle and bracing frame.
Placement figure when Fig. 4 is the embodiment of the invention 1 chromising.
Fig. 5 is the synoptic diagram of suspension bracket of the present invention.
Fig. 6 is the vertical view of suspension bracket of the present invention.
Fig. 7 is the guard circle and the supporting tube synoptic diagram of the embodiment of the invention 2.
Embodiment
Furnace temperature inequality when the problem that existing chromizing technique exists mainly contains chromising causes quality product to be difficult to guarantee, and the 2nd, stove internal corrosion atmosphere influences the heat retaining property and the work-ing life of body of heater.The inventive method uses pit furnace as chromising equipment, and the chromising jar is heated evenly, and is improved, and uses at least 2 thermopairs segmentation thermometric in stove, has guaranteed the homogeneity of temperature in the stove; Increase guard circle protection body of heater, prolong its work-ing life; Use suspension bracket and supporting tube, improved chromising efficient.In addition, consider that aggressive atmosphere makes progress away, adopt pit furnace also only to need bell is protected.
With specific embodiment the present invention is described below.
Embodiment 1: when chromising was handled, the chromising jar divided two-layer placement in pit furnace.
Fig. 1 is in the pit furnace body of heater diagrammatic cross-section, the about 2200mm of the external diameter of pit furnace, thermal insulation layer 1 wall thickness 340～360mm, the high 1840mm of stove, the effective headroom of burner hearth: the about 1450mm of internal diameter, the about 1500mm of clear height is provided with 2 thermopairs 2 along a side, apart from the about respectively 600mm of furnace bottom, 1200mm, total heating power 100kW, heat up fast in use temperature≤950 ℃, can reach 10～15 ℃/min, insulation better.
Fig. 2, Figure 3 shows that guard circle and bracing frame, consider the influence of furnace high-temperature, bracing frame and guard circle weld together, with the increase firmness.Guard circle and twere are every 30～40mm, and bracing frame adopts three and is about 600mm, and the round steel pipe of external diameter Φ 80～100mm is done support, along the furnace wall uniform distribution; Part adopts 3 angle steel (5 * 50mm) around the guard circle; thickness 8～10mm is adopted on top; the band steel of width 50～60mm is done the annular welding; and be close to the furnace wall and fix; the advantage of this design is: the suspension bracket that can will be loaded with the chromising jar easily lifts turnover and can not touch bosh brick body, stove silk; and help dividing two-layer placement with bin, it is higher to add heat transfer efficiencies.The angle steel number can suitably increase around the guard circle, but the influence when considering chromising heat should not be used too much.
Fig. 5, Fig. 6 are the suspension bracket synoptic diagram; adopt the round steel of diameter of phi 25mm to be welded; high 440mm; loading surface and body of heater, guard circle match; diameter 600mm; and press the distribution of supporting tube; locate leaving certain gaps uncovered by the economic plan for per about 120 °; can place 3 jars of chromising jars simultaneously, behind the loading chromising jar, when lifting turnover pit furnace; with the notch alignment supporting tube; can fall furnace bottom very reposefully, the slight swing when preventing upper air installing causes the slip of chromising jar, evenly has the round steel retaining of 6 high 200～300mm to stumble in the welding of the outer ring of suspension bracket loading surface.
Supporting tube can be provided with the 3-5 root, but because its breach of suspension bracket that is placed on furnace bottom will be aimed at supporting tube falls, the number of supporting tube should not be provided with too much, otherwise can strengthen hoisting difficulty, 3 supporting tubes of operated by rotary motion.During chromising in the stove temperature higher, the support to suspension bracket of bracing frame should be even, the loading surface that prevents suspension bracket is unbalance stress and being out of shape at high temperature.
More than used steel material all be Cr
25Ni
20, also can substitute, as high temperature resistant stainless steel 314,310s, 316 etc. with other close heat-resistance stainless steel.
(1) with part, chromizing agent stirring, tinning, sealing: pit furnace power 100kw, adopt 2 thermopairs to divide upper and lower two portions temperature control respectively.Treat that the chromising parts processed is an example with the bearing pin of diameter of phi 2.0～2.4mm, chromizing agent adopts the commercial goods, it is formulated by 55%: 42%: 3% weight ratio to be mainly aluminum oxide, ferrochrome powder, ammonium chloride, both are according to bearing pin: the chromizing agent weight ratio is to stir in 1: 2～1: 3, the jar end and the chromizing agent of spreading 10～15mm all around in advance, last capping is with the sposh sealed can mouth of water glass and refractory mortar furnishing;
(2) advance stove: carefully hang onto suspension bracket on driving the chromising jar of above-mentioned good seal, every layer of suspension bracket put 3 jars, according to turnout what, can divide 2 layers to put 6 jars at most, determine to place after the balance, with driving first suspension bracket is hung in the pit furnace, the notch alignment supporting tube of suspension bracket is fallen furnace bottom; When placing next suspension bracket, its breach and supporting tube are staggered, place on the supporting tube,, the layering in pit furnace of chromising jar is placed, cover enclosing cover as Fig. 4;
(3) chromising is carried out in interim intensification, insulation: be warming up to 200 ℃, be incubated 1 hour; Be warming up to 400 ℃, be incubated 2 hours; Be warming up to 450 ℃, be incubated 1 hour; Be warming up to 600 ℃, be incubated 1 hour; Be warming up to 800 ℃, be incubated 1 hour; Be warming up to 900～950 ℃, be incubated 9～11 hours;
(4) come out of the stove, screen: half-open fire door during chromising jar furnace cooling to 700 ℃, drop to below 500 ℃ and come out of the stove, cooled off again 2-3 hour, open jar a screening and separating part and a chromizing agent.
Detect every jar of surperficial Vickers' hardness of randomly drawing part, reach 950～1300HV0.2kg, chromizing layer thickness 0.005～0.015mm, the pin diameter only 0.005mm of great fluctuation process scope that rises, and originally adopted the box-type furnace chromizing technique to process same bearing pin part, the about 850HV0.2kg of its surperficial vickers hardness number, and the pin diameter about 0.005～0.015mm of great fluctuation process scope that rises.According to actual needs, can also carry out scrubbing, quenching, tempering, tumbling processing to the bearing pin part after the chromising processing after the screening.
Embodiment 2: when chromising was handled, the chromising jar divided 3 layers of placement in pit furnace.
Pit furnace can increase the placement of the chromising jar number of plies by amplifying, because body of heater increases, for guaranteeing furnace temperature, needs the number of corresponding increase temperature-control heat couple this moment, strengthens heating power.
When dividing multilayer to use the pit furnace structure still with embodiment 1 in identical, the about 2600mm of external diameter, thermal insulation layer wall thickness 340～360mm, the high 2440mm of stove, the effective headroom of burner hearth: the about 1850mm of internal diameter, the about 2100mm of clear height is provided with 3 thermopairs along a side, apart from the about respectively 600mm of furnace bottom, 1200mm, 1800mm, total heating power 150kW, heat up fast in use temperature≤950 ℃, can reach 10～15 ℃/min, insulation better.Consideration can be relatively easy to suspension bracket is lifted up into out pit furnace, and supporting tube is generally selected 3, identical among guard circle and hanger structure and the embodiment 1.
Fig. 7 is used for the stepped appearance supporting tube synoptic diagram that multilayer is placed the chromising jar, uses the round steel pipe of external diameter Φ 80～100mm, is provided with two-layer lateral brace frame, the about 600mm of interlamellar spacing.The loading surface radius of one deck suspension bracket should be slightly less than the distance of stove center to supporting tube in the middle of this moment, and the breach of suspension bracket loading surface when placing can be staggered with supporting tube.
More than used steel material also all use Cr
25Ni
20
(1) with part, chromizing agent stirring, tinning, sealing: pit furnace power 150kw, adopt 3 thermopairs to divide upper, middle and lower two portions temperature control respectively.Treat that the chromising parts processed is an example with the bearing pin of diameter of phi 2.0～2.4mm, chromizing agent adopts the commercial goods, it is formulated by 55%: 42%: 3% weight ratio to be mainly aluminum oxide, ferrochrome powder, ammonium chloride, both are according to bearing pin: the chromizing agent weight ratio is to stir in 1: 2～1: 3, the jar end and the chromizing agent of spreading 10～15mm all around in advance, last capping is with the sposh sealed can mouth of water glass and refractory mortar furnishing;
(2) advance stove: the chromising jar of above-mentioned good seal is carefully hung onto on the suspension bracket with driving, and every layer of suspension bracket put 3 jars, can divide 3 layers to put 9 jars, determine to place after the balance, when first suspension bracket entered, the notch alignment supporting tube of loading surface was fallen furnace bottom, second suspension bracket hangs in when arriving the first layer bracing frame, suspension bracket loading surface breach and supporting tube stagger, and suspension bracket is dropped on the bracing frame, hang in the 3rd suspension bracket again, drop on the second layer bracing frame, place and finish enclosing cover on the bonnet;
(3) chromising is carried out in interim intensification, insulation: be warming up to 200 ℃, be incubated 1 hour; Be warming up to 400 ℃, be incubated 2 hours; Be warming up to 450 ℃, be incubated 1 hour; Be warming up to 600 ℃, be incubated 1 hour; Be warming up to 800 ℃, be incubated 1 hour; Be warming up to 900～950 ℃, be incubated 9～11 hours;
(4) come out of the stove, screen: half-open fire door when half-open fire door, chromising jar furnace cooling to 700 ℃, drop to below 500 ℃ and come out of the stove, cooled off again 2-3 hour, open jar a screening and separating part and a chromizing agent.
Detect every jar of surperficial Vickers' hardness of randomly drawing part, reach 950～1300HV0.2kg, chromizing layer thickness 0.005～0.015mm, the pin diameter only 0.005mm of great fluctuation process scope that rises, and originally adopted the box-type furnace chromizing technique to process same bearing pin part, the about 850HV0.2kg of its surperficial vickers hardness number, and the pin diameter about 0.005～0.015mm of great fluctuation process scope that rises.According to actual needs, can also carry out scrubbing, quenching, tempering, tumbling processing to the bearing pin part after the chromising processing after the screening.
The present invention all adopts the driving lifting in part turnover stove process, changed the behindhand type that original box-type furnace manually pulls.Divide the layer 2-3 chromising enough in the general stove, arrange accordingly thermopair 2-3 props up, the lifting of body of heater when too conference influence suspension bracket turnover body of heater, and required heating power is big, the excessive homogeneity that also is difficult for keeping the interior temperature of stove of furnace chamber.The present invention can also be generalized among the part processing of similar other close kind, and those skilled in the art can be easy to digest.
Claims (7)
1. method of using the pit furnace chromising, it is characterized in that adopting pit furnace as chromising equipment, described pit furnace uses at least 2 thermocouple temperature measurements, thermopair is distributed on the sidewall by the high equal proportion of stove, the chromising jar is evenly put along the furnace wall during chromising, the layering in pit furnace of chromising jar is placed: the body of heater bottom is provided with 3-5 root supporting tube, along the furnace wall uniform distribution, at least be provided with 1 lateral brace frame on the every supporting tube, the chromising jar is placed on and passes in and out pit furnace on the suspension bracket, the leaving certain gaps uncovered by the economic plan of suspension bracket loading surface when loading the chromising jar and lifting into pit furnace, is fallen furnace bottom with the notch alignment supporting tube of suspension bracket; When placing next suspension bracket, its loading surface breach and supporting tube are staggered, place on the lateral brace frame, the layering in pit furnace of chromising jar is placed.
2. the method for use pit furnace according to claim 1 chromising; it is characterized in that described pit furnace inside is equipped with guard circle protection bosh brick body and stove silk; guard circle and twere are every 30～40mm, and the guard circle main body uses 3 steel pipes to surround at least, and the top of guard circle is close to the furnace wall and is fixed.
3. the method for use pit furnace according to claim 1 and 2 chromising, the outer ring that it is characterized in that the suspension bracket loading surface are provided with the retaining device of stumbling, and are used for preventing that hoisting process chromising jar from rocking or skidding off suspension bracket.
4. the method for use pit furnace according to claim 1 and 2 chromising is characterized in that chromising jar, pit furnace stove silk, guard circle, supporting tube, suspension bracket material are heat-resistance stainless steel.
5. the method for use pit furnace according to claim 3 chromising is characterized in that chromising jar, pit furnace stove silk, guard circle, supporting tube, suspension bracket material are heat-resistance stainless steel.
6. the method for use pit furnace according to claim 4 chromising is characterized in that heat-resistance stainless steel selects Cr for use
25Ni
20
7. the method for use pit furnace according to claim 5 chromising is characterized in that heat-resistance stainless steel selects Cr for use
25Ni
20
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101318990A CN101126146B (en) | 2007-09-21 | 2007-09-21 | Chromizing method by using shaft furnace |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101318990A CN101126146B (en) | 2007-09-21 | 2007-09-21 | Chromizing method by using shaft furnace |
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| Publication Number | Publication Date |
|---|---|
| CN101126146A CN101126146A (en) | 2008-02-20 |
| CN101126146B true CN101126146B (en) | 2010-06-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2007101318990A Expired - Fee Related CN101126146B (en) | 2007-09-21 | 2007-09-21 | Chromizing method by using shaft furnace |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115821201A (en) * | 2022-11-24 | 2023-03-21 | 西北有色金属研究院 | Preparation method of high-frequency induction pulse heating rapid chromizing coating on stainless steel surface |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2035072U (en) * | 1988-01-18 | 1989-03-29 | 许能潮 | Gas permeation shaft furnace without internal muffle sleeve |
| CN1039624A (en) * | 1988-06-24 | 1990-02-14 | 燃烧工程有限公司 | Method of chromizing articles and equipment |
| CN1213014A (en) * | 1997-09-26 | 1999-04-07 | 麦克德莫技术股份有限公司 | Improved method for chromizing small parts |
| US20020025376A1 (en) * | 2000-07-27 | 2002-02-28 | Heinrich Walter | Process and apparatus for chroming an inner surface of a component |
| GB2421032A (en) * | 2004-12-11 | 2006-06-14 | Siemens Ind Turbomachinery Ltd | A method of protecting a component against hot corrosion |
-
2007
- 2007-09-21 CN CN2007101318990A patent/CN101126146B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2035072U (en) * | 1988-01-18 | 1989-03-29 | 许能潮 | Gas permeation shaft furnace without internal muffle sleeve |
| CN1039624A (en) * | 1988-06-24 | 1990-02-14 | 燃烧工程有限公司 | Method of chromizing articles and equipment |
| CN1213014A (en) * | 1997-09-26 | 1999-04-07 | 麦克德莫技术股份有限公司 | Improved method for chromizing small parts |
| US20020025376A1 (en) * | 2000-07-27 | 2002-02-28 | Heinrich Walter | Process and apparatus for chroming an inner surface of a component |
| GB2421032A (en) * | 2004-12-11 | 2006-06-14 | Siemens Ind Turbomachinery Ltd | A method of protecting a component against hot corrosion |
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|---|---|
| CN101126146A (en) | 2008-02-20 |
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