CN1159372A - Bell socket sand core for centrifugal casting iron drain-pipe and production method thereof - Google Patents
Bell socket sand core for centrifugal casting iron drain-pipe and production method thereof Download PDFInfo
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- CN1159372A CN1159372A CN 96121293 CN96121293A CN1159372A CN 1159372 A CN1159372 A CN 1159372A CN 96121293 CN96121293 CN 96121293 CN 96121293 A CN96121293 A CN 96121293A CN 1159372 A CN1159372 A CN 1159372A
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- core
- sand
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- bell socket
- pipe
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Abstract
The present invention relates to a cement mouthing sand core for centrifugally-casting cast iron drain pipe and its production method. The composition of said invented cement mouthing sand core is composed of (wt%) 70-75% of natural silica sand whose SiO2 content is above 90%, 2.4-3.6% of bentonite, 12-14% of high-grade Portland cement, 0.2-0.4% of pure polyvinyl alcohol and 10-13% of water. As compared with production process of synthetic fatty acid bonded core said invention can save the steps of heating and drying, and can simplifying production process. Besides, it uses the cement as bonding material, so that the cost for making mouthing sand core can be greatly reduced.
Description
The present invention relates to special type (centrifugal) casting field of foundry, specifically be meant a kind of core and production method thereof that is used to produce the centrifugal cast iron drainpipe of being with bellmouth.
In October, 1994, publish by China Machine Press, the 9th, ten chapters of " spun cast pipe " book that Liu Qingxing writes have been set forth the requirement of spun cast pipe to bell socket sand core, introduced present China spun cast pipe factory commonly used close multiple bell socket sand core and proportioning and performances such as fat sand and resin sand.Because the employed core of centrifugal cast iron pipe, its dry strength should be more much higher than the sand core strength that general casting method is used, and therefore, point out emphatically in " spun cast pipe " book: " cast tube is in forming process; exist powerful centrifugal force, and bell socket sand core must have certain intensity (8～10 * 10
5Pa).General use is closed fat sand and can be satisfied instructions for use ".The proportioning and the performance of closing fat sand are as shown in table 1:
Table 1 closes fat sand proportioning and performance
The mixed grind technology of closing fat sand is: add earlier silica sand → addings bentonite → addings dextrin or spent pulping liquor → add water → adduction fat, added water dried in the past mixed 2～3 minutes, added behind the water wet mixing 8～10 minutes.The bake out temperature that closes the fat core is 200～240 ℃.
| Percentage by weight | Performance | ||||||
| Silica sand | Close fat | Bentonite | Dextrin (or spent pulping liquor) | Water | Gas permeability | Green compression strength MPa | Baked tensile strength MPa |
| 100 | 4～4.5 | ?1.5～2 | 1～1.5 (1～2.0) | 2.5～3.5 | 7.1 | ?0.01～0.015 | ?1.2～1.6 |
Can satisfy the instructions for use that spun cast pipe is produced though close the fat core, but as can be seen from above-mentioned employed raw material and technology, the prices of raw and semifnished materials of closing the fat core are more expensive, complex manufacturing and necessary drying process, a large amount of heat energy have been consumed, increase manufacturing cost, therefore closed fat core cost height.As everyone knows, building a building cylinder iron, drainpipe is a kind of low value product, domestic in recent years many spun cast pipe factory is forced to stop production because of deficiency in economic performance, so reducing production costs, improve overall economic efficiency has become the difficult problem that domestic each tame spun cast pipe factory presses for solution.
The objective of the invention is to overcome the deficiencies in the prior art part, promptly by changing the core prescription and simplifying the method for preparing core technology, realize reducing the core cost, improve the core sand performance, for spun cast pipe factory provides bell socket sand core for centrifugal casting iron drain-pipe and the production method thereof that a kind of cost of raw material is cheap, core manufacturing craft is simple and energy consumption is low.
The objective of the invention is to realize by following measure:
A kind of bell socket sand core for centrifugal casting iron drain-pipe is characterized in that by weight percentage each component proportioning is for containing SiO
2More than 90%, the sand grains diameter is the natural silica Sand 70～75% of 0.105mm～0.21mm, bentonite 2.4～3.6%, high grade silicate cement 12～14%, pure polyvinyl alcohol 0.2～0.4% and water 10～13%.
A kind of production method of bell socket sand core for centrifugal casting iron drain-pipe is characterized in that feeding intake by core component and proportioning thereof, and the production method of saving after the heating, drying program is as follows:
(1) dried mixing
Drop into silica sand, adhesive bentonite and adhesive silicate high-mark cement by proportioning, do and mixed 2～3 minutes;
(2) wet mixing
By proportioning water is poured in the polyvinyl alcohol water solution and to be mixed, then water and polyvinyl alcohol mixing liquid were fully mixed 3～5 minutes with the material of doing after mixing;
(3) coremaking
Material after at first utilizing aluminium matter core box with wet mixing is made core, molding was sprayed water 2～4 times to core in 1～2 day after 3 hours, then core was placed on the core shelf natural air drying 1～2 day, on the core working surface, be coated with one deck blacking at last, be bell socket sand core for centrifugal casting iron drain-pipe provided by the invention.
The present invention compared with prior art has following advantage:
1, the present invention is satisfying on the basis of spun cast pipe with the bell socket sand core performance requirement, reduced the bell socket sand core cost significantly, at first, it selects for use low-cost cement to make binding agent, the binding agent that alternative price is more expensive closes fat or resin, and the cost of raw material is greatly reduced; Secondly, compare with the resin that also can satisfy the instructions for use of spun cast pipe production, the core manufacturing craft that closes the fat core, simplified production routine, particularly saved the heating, drying processing step, save the energy that the core heating, drying is consumed, further reduced the production cost of core again.Cement bell socket sand core production cost only is 25～35% of a resin sand core production cost, only for closing 40～50% of fat core production cost.On probation by Fujian cast tube factory, than 90～100 yuan of the present cost savings of using of closing fat core cast tube per ton of this factory.
2, cement bonded sand main performance provided by the invention is as shown in table 2:
Table 2 cement bonded sand performance
| Gas permeability | Green compression strength MPa | Baked tensile strength MPa |
| 6.0～8.0 | 0.023～0.032 | 0.6～1.2 |
Table 2 shows that the bell socket sand core of the present invention's preparation has higher dry strength.Operating position shows that core has good anti-stick grittiness energy, and therefore collapsibility and not stickness have preferably reached the spun cast pipe requirement fully, and the cast tube quality of producing is good.
3, because the present invention has saved the heating, drying processing step, not only saved the disposable apparatus investment cost, and saved the labour of daily oven dry and improved workman's working condition.
The present invention is described in further detail by following embodiment:
A kind of bell socket sand core for centrifugal casting iron drain-pipe is made up of the mixed liquor of natural silica Sand, bentonite, high grade silicate cement and additives polyvinyl alcohol and water, and its proportioning is as shown in table 3:
The proportioning embodiment of table 3 cement core
| Silica sand (gram) | Bentonite (gram) | Portland cement (gram) | The polyvinyl alcohol % aqueous solution (concentration 10%) (milliliter) | Water (milliliter) | |
| Embodiment 1 | 1000 | 48 | 170 | 28 | 140 |
| Embodiment 2 | 1000 | 34 | 180 | 36 | 175 |
In the table, silica sand is meant and contains SiO
2Natural silica Sand more than 90%, its sand grains diameter is 0.105～0.21mm, and bentonite embodiment 1 refers to that the sucking amount of Zhejiang enemy mountain products is the 33g/100g material, and embodiment 2 refers to that the sucking amount that is produced from the Jiutai city is the 27.14g/100g material; Cement embodiment 1 is 525
#Portland cement, embodiment 2 is 425
#Portland cement, the trade mark of polyvinyl alcohol are PVA17-88.
Compare with the core manufacturing craft that closes the fat core with resin sand core, the production method of having omitted the heating, drying processing step is as follows:
(1) dried mixing
Proportioning by embodiment in the proportioning table 1,2 is thrown people's silica sand, bentonite and portland cement respectively, does and mixes 2～3 minutes;
(2) wet mixing
By the proportioning of embodiment in the proportioning table 1,2 water is poured in 10% the polyvinyl alcohol water solution and mixed, then mixed liquor was fully mixed 3～5 minutes with the material of doing after mixing;
(3) coremaking
Material after at first utilizing aluminium matter core box with wet mixing is made core, molding was sprayed water 2～4 times to core in 1～2 day after 3 hours, then core was placed on the core shelf natural air drying 1～2 day, on the core working surface, be coated with one deck blacking at last, promptly produce bell socket sand core for centrifugal casting iron drain-pipe provided by the invention.
Raw material of the present invention and proportioning thereof select according to as follows:
The present invention selects for use cheap portland cement to substitute the higher resin of price and closes fat and make the bell socket sand core adhesive, also can obtain the needed dry strength of bell socket sand core for centrifugal casting iron drain-pipe.Its reason is according to the setting and harden mechanism of cement as the adhesive of bell socket sand core.
The statistics that present domestic shaft kiln cement plant is produced, Portland clinker mineral composition general range is:
Tricalcium silicate 3CaOSiO
2(C
2S) 45～56%
Dicalcium silicate 2CaOSiO
2(C
2S) 20～30%
Tricalcium aluminate 3CaOAl
2O
3(C
3A) 6～10%
Tetra calcium aluminoferrite 4CaOAl
2O
3Fe
2O
3(C
4AF) 13～17%
Above-mentioned four kinds of mineral compositions are the Main Ingredients and Appearances that influence cement performance.Wherein the tricalcium silicate hydration rate is fast, and fast solidifying is the principal element that produces intensity, and its content is high more, and the label of cement is just high more, and the present invention adopts the purpose of high-mark cement, is in order to improve the early strength of core; The hydration rate of tricalcium aluminate is the fastest, rate of set is exceedingly fast, and can promote the aquation of silicate mineral, if too high levels, can cause cement setting too fast, shorten the up time of core sand, influence coremaking, therefore, in the cement that the system core is used, require its content＜10%, in Portland cement, its content generally can both satisfy this requirement; Tetra calcium aluminoferrite mainly plays fluxing action, and it can reduce the sintering temperature of grog, helps forming tricalcium silicate, thereby improves the quality of cement.
Cement is very complicated physics process as the setting and harden process of the binding agent of bell socket sand core, roughly can be divided into dissolving, gel and three processes continuous and intersection is carried out of crystallization.
Course of dissolution: cement one contact wetting just begins hydration reaction, is preface by its hydration rate speed, generates drated calcium aluminate, hydrated calcium ferrite and hydrated calcium silicate etc.As shown in the formula:
4CaOAl
2O
3Fe
2O
3+ 7H
2O 3CaOAl
2O
36H
2O+CaOFe
2O
3H2O (aquation iron
Acid calcium)
If moisture is enough, wherein generating hydrated calcium silicate is topmost reaction, and hydrated calcium silicate and hydrated calcium ferrite are gelinites, and the gelling of hydrated calcium silicate is the strongest, and whole intensity is the highest.
The gel process: when the concentration of hyrate in water of cement reached capacity, hyrate was just separated out with superfine solid particle, becomes colloid, along with constantly carrying out of hydration, newborn colloid grain constantly increases, and makes gel retrogradation gradually, and cement mortar loses plasticity to begin to condense.
Crystallization process: after cement mortar condensed, also unhydrated cement granules continued to absorb moisture and carries out hydration reaction in the gelinite.Therefore the moisture of gelinite is seized and tight gradually.Simultaneously, calcium hydroxide and drated calcium aluminate also are transformed into acicular crystal from colloidal state, and insert in the gel of calcium silicate body, make cement have intensity.
Above-mentioned mechanism shows that amount of water is a key technology.The present invention is a foundation with the experiment, determines amount of water and water spraying time and number of times, to satisfy its requirement.
The present invention adopts bentonite to make binding agent, in order to obtain the green compression strength of bell socket sand core.Bentonite has active and can expand, and dilation is bentonitic main performance index, but the dilation size is fully not corresponding with the quality quality, and bentonite could reflect its green compression strength preferably to the adsorbance size of methylene blue.Therefore, it is that the bentonite that 27～42g/100g expects is a binding agent that the present invention selects the sucking amount in Jiutai, Gongzhuling, Jilin, enemy mountain, Zhejiang and Xinyang, Henan etc. for use, and its addition requires to be as the criterion the least possible adding can reach minimum green compression strength.
It is additive that the present invention has selected nontoxic, tasteless organic high molecular compound polyvinyl alcohol for the collapsibility that improves core, and it is the PVA17-88 polyvinyl alcohol that present embodiment is selected the trade mark for use, the aqueous solution performance such as the table 4 of its 20 ℃ of 10% concentration:
Table 4 PVA17-88 performance
| Project | PH value | Volatile matter % | Sodium acetate % | Viscosity *CP |
| Index | 5～7 | ≤5.0 | ≤1.0 | 20～25 |
The present invention adopts and contains SiO
2More than 90%, the sand grains diameter is the natural silica Sand of 0.105～0.21mm because the granularity of silica sand, size distribution and granular be the key factor of decision spun cast pipe bell socket sand core performance.Therefore, bell socket sand core must be evenly with the size distribution of sand, and size particles should not have big difference; Granular circle or half rhombus of should be; Granularity is that diameter is in the scope of 0.105～0.21mm at 70～140 orders.
The reason that the present invention omits heating, drying processing step of the prior art is: the purpose of heating, drying core is to make core obtain enough dry strength in the prior art, the present invention adds an amount of water in charge ratio, can make core obtain suitable green compression strength, but this water yield can only make core obtain lower dry strength, in order to make core further obtain dry strength, must increase the moisture of core, for this reason, in core manufacturing craft, molding was sprayed water 2～4 times to core in 1～2 day after 3 hours, made core obtain enough dry strength.
Claims (4)
1, a kind of bell socket sand core for centrifugal casting iron drain-pipe that contains silica sand, bentonite and water is characterized in that it also contains adhesive portland cement and additives polyvinyl alcohol.
2, a kind of bell socket sand core for centrifugal casting iron drain-pipe according to claim 1 is characterized in that its each component proportioning by weight percentage is: contain SiO
2Natural silica Sand 70～75% more than 90%, bentonite 2.4～3.6%, high grade silicate cement 12～14%, pure polyvinyl alcohol 0.2～0.4%, water 10～13%.
3,, it is characterized in that the natural silica Sand particle size diameter is the circular or half rhombus particle of 0.105～0.21mm according to claim 1,2 described a kind of bell socket sand core for centrifugal casting iron drain-pipe.
4, a kind of production method of bell socket sand core for centrifugal casting iron drain-pipe is characterized in that feeding intake by the component and the proportioning thereof of bell socket sand core, and the production method of saving after the heating, drying program is as follows:
(1) dried mixing
Contain SiO by the proportioning input
2Natural silica Sand more than 90%, bentonite and high grade silicate cement are done and were mixed 2～3 minutes;
(2) wet mixing
By proportioning water is poured in 10% the polyvinyl alcohol water solution and mixed, then mixed liquor was fully mixed 3～5 minutes with the material of doing after mixing;
(3) material after at first utilizing aluminium matter core box with wet mixing is made core, molding was sprayed water 2～4 times to core in 1～2 day after 3 hours, then core is placed on the core shelf natural air drying 1～2 day, and on the core working surface, was coated with one deck blacking at last, promptly get product.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96121293A CN1045733C (en) | 1996-12-16 | 1996-12-16 | Bell socket sand core for centrifugal casting iron drain-pipe and production method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96121293A CN1045733C (en) | 1996-12-16 | 1996-12-16 | Bell socket sand core for centrifugal casting iron drain-pipe and production method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1159372A true CN1159372A (en) | 1997-09-17 |
| CN1045733C CN1045733C (en) | 1999-10-20 |
Family
ID=5126843
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN96121293A Expired - Fee Related CN1045733C (en) | 1996-12-16 | 1996-12-16 | Bell socket sand core for centrifugal casting iron drain-pipe and production method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1045733C (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103167918A (en) * | 2011-10-14 | 2013-06-19 | 有限会社小松铸型制作所 | Shaping material, functional agent, shaped product, and product |
| CN104338901A (en) * | 2014-10-22 | 2015-02-11 | 东方电气集团东方汽轮机有限公司 | Method for repairing precise investment casting silica sol mold shell and mold shell wax outlet plugging material |
| CN105537523A (en) * | 2016-02-22 | 2016-05-04 | 江苏钜源机械有限公司 | Method for casting double-end blind hole part at negative pressure through evanescent mode |
| CN108273957A (en) * | 2018-03-08 | 2018-07-13 | 湖北工业大学 | A kind of spun cast pipe bell socket sand core cast paint and preparation method thereof |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU954137A1 (en) * | 1980-07-14 | 1982-08-30 | Чувашский государственный университет им.И.Н.Ульянова | Mixture for producing casting moulds and cores hardened by heat drying |
| SU1586847A1 (en) * | 1988-10-06 | 1990-08-23 | Всесоюзный Проектно-Технологический Институт Литейного Производства | Sand for making moulds and cores hardened with carbon dioxide |
| CN1097661A (en) * | 1993-07-17 | 1995-01-25 | 罗端权 | Novel casting binder and manufacture method thereof |
| CN1035864C (en) * | 1994-05-07 | 1997-09-17 | 张炳春 | Binder for sand mould and its mfg. method |
-
1996
- 1996-12-16 CN CN96121293A patent/CN1045733C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103167918A (en) * | 2011-10-14 | 2013-06-19 | 有限会社小松铸型制作所 | Shaping material, functional agent, shaped product, and product |
| CN103167918B (en) * | 2011-10-14 | 2015-11-25 | 有限会社小松铸型制作所 | Moulding material, functional agent, model articles and goods |
| CN104338901A (en) * | 2014-10-22 | 2015-02-11 | 东方电气集团东方汽轮机有限公司 | Method for repairing precise investment casting silica sol mold shell and mold shell wax outlet plugging material |
| CN105537523A (en) * | 2016-02-22 | 2016-05-04 | 江苏钜源机械有限公司 | Method for casting double-end blind hole part at negative pressure through evanescent mode |
| CN108273957A (en) * | 2018-03-08 | 2018-07-13 | 湖北工业大学 | A kind of spun cast pipe bell socket sand core cast paint and preparation method thereof |
| CN108273957B (en) * | 2018-03-08 | 2019-11-12 | 湖北工业大学 | A kind of spun cast pipe bell socket sand core cast paint and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1045733C (en) | 1999-10-20 |
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