CA1078131A - Method for knocking out silicate-bonded mould material from a mould after casting - Google Patents
Method for knocking out silicate-bonded mould material from a mould after castingInfo
- Publication number
- CA1078131A CA1078131A CA255,890A CA255890A CA1078131A CA 1078131 A CA1078131 A CA 1078131A CA 255890 A CA255890 A CA 255890A CA 1078131 A CA1078131 A CA 1078131A
- Authority
- CA
- Canada
- Prior art keywords
- mould
- aqueous solution
- casting
- mould material
- silicate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000463 material Substances 0.000 title claims abstract description 46
- 238000005266 casting Methods 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000007864 aqueous solution Substances 0.000 claims abstract description 27
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000011230 binding agent Substances 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 6
- 229910021529 ammonia Inorganic materials 0.000 claims description 4
- 238000005406 washing Methods 0.000 claims description 3
- 239000000243 solution Substances 0.000 abstract description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 27
- 239000004576 sand Substances 0.000 description 24
- 150000002148 esters Chemical class 0.000 description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- URAYPUMNDPQOKB-UHFFFAOYSA-N triacetin Chemical compound CC(=O)OCC(OC(C)=O)COC(C)=O URAYPUMNDPQOKB-UHFFFAOYSA-N 0.000 description 7
- 239000004348 Glyceryl diacetate Substances 0.000 description 5
- 235000019443 glyceryl diacetate Nutrition 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 235000019353 potassium silicate Nutrition 0.000 description 5
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 229910001208 Crucible steel Inorganic materials 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 239000004848 polyfunctional curative Substances 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229960002622 triacetin Drugs 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 235000013773 glyceryl triacetate Nutrition 0.000 description 3
- 239000001087 glyceryl triacetate Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 150000002895 organic esters Chemical class 0.000 description 3
- 230000008929 regeneration Effects 0.000 description 3
- 238000011069 regeneration method Methods 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000006004 Quartz sand Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000010297 mechanical methods and process Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229920001353 Dextrin Polymers 0.000 description 1
- UXDDRFCJKNROTO-UHFFFAOYSA-N Glycerol 1,2-diacetate Chemical compound CC(=O)OCC(CO)OC(C)=O UXDDRFCJKNROTO-UHFFFAOYSA-N 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- FYGDTMLNYKFZSV-MRCIVHHJSA-N dextrin Chemical compound O[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)OC1O[C@@H]1[C@@H](CO)OC(O[C@@H]2[C@H](O[C@H](O)[C@H](O)[C@H]2O)CO)[C@H](O)[C@H]1O FYGDTMLNYKFZSV-MRCIVHHJSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- -1 ethyl diglycol diacetate Chemical compound 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 235000012054 meals Nutrition 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229960001866 silicon dioxide Drugs 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- ILJSQTXMGCGYMG-UHFFFAOYSA-N triacetic acid Chemical compound CC(=O)CC(=O)CC(O)=O ILJSQTXMGCGYMG-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
- B22D29/001—Removing cores
- B22D29/002—Removing cores by leaching, washing or dissolving
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mold Materials And Core Materials (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
- Polymerisation Methods In General (AREA)
- Silicon Polymers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A method for knocking out silicate-bonded granular mould material from a mould after casting. This method is characterized in that the mould after casting is contacted with an alkaline aqueous solution to loosen the bond between the grains by dissolving the silicate binder, and release the mould material. The cast mould can be immersed in a bath of the solution, or poured over or sprinkled or sprayed with the alkaline aqueous solution. The method avoids the awkward mechanical knock-out of the hardened mould material and the drawbacks connected therewith.
A method for knocking out silicate-bonded granular mould material from a mould after casting. This method is characterized in that the mould after casting is contacted with an alkaline aqueous solution to loosen the bond between the grains by dissolving the silicate binder, and release the mould material. The cast mould can be immersed in a bath of the solution, or poured over or sprinkled or sprayed with the alkaline aqueous solution. The method avoids the awkward mechanical knock-out of the hardened mould material and the drawbacks connected therewith.
Description
~7~13~1 In the production of moulds and cores for casting metallic materials such as cast iron, cast steel, li~ht metals, bronzes, e-tc., there is often used a mould material containing sand and a silicate-binder, usually water glass. The silicate can be hardened, among other things, with the help of an organic ester, for example triacetine, which is mixed into the mould material, or with carbon dioxide which is led throu~h produced cores or moulds. The hardening takes place under precipitation of silicagel which bonds the sand grains and is usually performed at room temperature. When using esterhardening sand and ester are normally mixed first, wherea~ter the silicate is supplied to the mixture of sand and ester. Immediately after the sili-cate has been mixed in, the mould is prepared. The pattern can usually be drawn after 15 to 30 minutes whereas casting is possible only after a couple of hours.
A generally recognized problem with silicate-bonded mould materials are their poor break-down properties, which necessi-tates an awkward mechanical knock-out of the hardened mould material, for example with a vibrator and also a sledge, to expose the cast body. The knock-out operation is a hard manual operation in a dusty and noisy environment. The mould residues consisting of silicate-bonded lumps of sand in varying sizes and reinfoFcing iron bars are carried away to be dumped on a waste disposal ~ip, alternatively to be sabjected to regeneration in a special plant.
. ~. - . .
107~
It i~ known that the break-down proper-ties of silicate-bonded mould materials can be improved by adding to the mould material different organic substances such as sugar, dextrine, starch, wood meal and pulverized coal. The improvement of the break-down properties tha-t can be achieved by adding said substances, however, far from solves the knock-out problems.
Also when usin~ the additives it is necessary -to e~ploy mechanical methods.
According to the present invention it has been found to be possible, when knocking out silicate-bonded mould material, to avoid awkward mechanical methods and thus the drawbacks connected therewith. The knock-out o the mould material and -the exposure of a casting with high quality can be radically ~acilitated according to the invention. In addition the method according to the invention has the advantage of making possible, with simple methods, regeneration of the used mould material so that this can be re-used for manuacture of new moulds and cores.
The present invention therefore provides a method of knocking out silicate-bonded granular mould material from a mould after casting, i.e. from a mould with a casting, possibly containing a core, characterized in that the mould after casting is contacted with an alkaline aqueous solution to loosen the bond between the grains by dissolving the silicate binder, and release the mould material.
The cast mould can be subjected, among other things, - to the effect of an alkaline aqueous solution by being immersed in a bath of the solution or by being poured over or sprinkled or sprayed with the alkaline aqueous solution. Pouring, -sprinkling and spraying in many cases involve advantages over immersion because with such methods it is possible to achieve a successive removal o mould material broken down from the surface of the mould so that the underlying mould material is more effectively accessible to the alkaline aqueous solution.
A generally recognized problem with silicate-bonded mould materials are their poor break-down properties, which necessi-tates an awkward mechanical knock-out of the hardened mould material, for example with a vibrator and also a sledge, to expose the cast body. The knock-out operation is a hard manual operation in a dusty and noisy environment. The mould residues consisting of silicate-bonded lumps of sand in varying sizes and reinfoFcing iron bars are carried away to be dumped on a waste disposal ~ip, alternatively to be sabjected to regeneration in a special plant.
. ~. - . .
107~
It i~ known that the break-down proper-ties of silicate-bonded mould materials can be improved by adding to the mould material different organic substances such as sugar, dextrine, starch, wood meal and pulverized coal. The improvement of the break-down properties tha-t can be achieved by adding said substances, however, far from solves the knock-out problems.
Also when usin~ the additives it is necessary -to e~ploy mechanical methods.
According to the present invention it has been found to be possible, when knocking out silicate-bonded mould material, to avoid awkward mechanical methods and thus the drawbacks connected therewith. The knock-out o the mould material and -the exposure of a casting with high quality can be radically ~acilitated according to the invention. In addition the method according to the invention has the advantage of making possible, with simple methods, regeneration of the used mould material so that this can be re-used for manuacture of new moulds and cores.
The present invention therefore provides a method of knocking out silicate-bonded granular mould material from a mould after casting, i.e. from a mould with a casting, possibly containing a core, characterized in that the mould after casting is contacted with an alkaline aqueous solution to loosen the bond between the grains by dissolving the silicate binder, and release the mould material.
The cast mould can be subjected, among other things, - to the effect of an alkaline aqueous solution by being immersed in a bath of the solution or by being poured over or sprinkled or sprayed with the alkaline aqueous solution. Pouring, -sprinkling and spraying in many cases involve advantages over immersion because with such methods it is possible to achieve a successive removal o mould material broken down from the surface of the mould so that the underlying mould material is more effectively accessible to the alkaline aqueous solution.
- 2 -~7~
Particularly in the case of knock-out of cores the spray method may be valuable since removal of sand is normally more trouble-some with cores. A suitable pressure on the aqueous solution in the case of spraying may be from 1 to 50 atmospheres. If it is desirable at the same time to expose a metallic, pure surface on the castings, it may be necessary to use a higher pressure, for example from 50 to 300 atmospheres. For economical reasons the aqueous solution, after it has been used for pouring, sprinkling or spraying of the mould after casting and after it has been separated from the releasecl sand, should be recirculated to the knock-out equipment to be used for pouring, sprinkliny or spraying oE new cast moulds.
.
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The mould oE silicate-bonded mould material may be manufactured in conventional manner. Thus, the mould material may be manufactured from quartz sand, chromite sand, olivine sand or more other sand used within the casting technique.
~s binder Eor the sa~d there is prefer~ed water glass, but also other water-soluble silicates are possible to use, T~e amount of silicate that is added when preparing the mould material suit-ably is from 0.5 to 5 % of the weight of the sand. The sili-cate is normally added in the form of an aqueous solution~ In the amount of silicate mentioned above the water isnot included.
The hardening may be performed in any conventional manner, hardening with carbon dioxide and with organic ester being of particular importance, but hardening with other substances mixed into the mould material than organic ester, such as acids, cement, dicalcium silicaté and silicon, may be used as well.
Esters which are often used as hardeners are mixtures of diacetin (glyceryl diacetate) and triacetin ~lyceryl tria-cetate) or mixtures of diacetin and ethyl diglycol diacetate in various weight ratios depending on the desired hardening times. The esters mentioned may also be used separately. Also other estersmay be usedJ among other things acetates of glycol. ;-The amount of ester added to the sand when preparing the mould material suitably is from 0.05 to 2% of the weight of the sand.
When manufacturing a mould for ester hardening the mixture of the components may be carried out, for example, in a continuous screw mixer, sand and ester being normally mixed before the silicate is added, as mentioned earlier. Among other things, the mould can be manufactured by allowing the mould material, after mixing in the silicate, to run down over the pattern which ,."
is suitably vibrated or rammed. When the mould has been allowed to harden 15-30 minutes the pattern can be drawn. ~he top and bottom parts of the mould are then put togethe~ after a few ~, ... , . - . ~ - , '~ ' :~7~ 3~
additional hours o~ hardening. Casting is usually performed after six hours at the earliest. casting may be performed, for example, from a bottom-discharging ladle. Any cores used can be manufactured in a corresponding manner, if desired. When the castin~ has cooled, the cast mould is treated with the alkaline aqueous solution in accordance wi~h the present inven-tion.
The alkaline aqueous solution can be produced by dissolv-ing sodium hydroxide, potassium hydroxide and/or another alkali 10 metal hydroxide and/or ammonia in water. Other substances than -those mentioned giving aqueous solutions with sufficient alkali-. ~.
nity may, of course, be used as well. The pH value of the aqueous solution suitably amounts to at least 12, and preferably to at least 13. When using alkali metal hydroxide to achieve the alkalinity the amount of alkali metal hydroxide should be at least 0.4 %, suitably 0.4 to 20 % and preferably 0.4 to 10 % -of the total weight of hydroxide and water. When using ammonia there is preferred an amount of 10 to 30 % of the total weight -of ammonia and water. ~
::
An increase of the temperature of the aqueous solution improves the break down markedly. In particular if there are .
problems in breaking down themould material located adjacent to the castings and;therefore exposed to the most heat, it may be essential to raise the temperature of the aqueous solution. If such problems exist the use of a high content of alkali metal hydroxide in the aqueous solution is also recommended~ The ;
temperature of the aqueous solution is suitably at least 40C
and suitably at the most 100C, preferably 50 to 80C. The treatment is normally carried out at atmospheric pressure for a time o~ from one minute to one hour.
When the castings have been exposed from the mould material they are made clean by water, for example by washing or rinsing.
- ~07~3~3~
The mould material broken down in the form of sand contaminated with alkali metal hydroxide can be used after -cleaning - consisting in repeated rinsing with water and subsequent drying - for manufacturing a new mould material, i.e. the mould material can be re-used. When using ester hardeners, ester is first mixed into the cleaned mould material, as described earlier~ and then water glass or anotller silicate binder. The mould material is thereaEter ready for manufacture of new moulds.
Embodiments of the invention are described in the follow-ing examples.
Exa~ple 1 A mould material is manufactured of quartz sand with a medium grain size of 0.25 mm. The sand is first mixed with 0.4 per cent by weight (calculated on the sand) of an ester hardener consisting of a mixture of equal parts of diacetin and triacetin and thereafter with 4 per cen~ by weight (calcul~
- ated on the sand) of water glass containing 40 per cent by weight of silicate and 60 per cent by weight of water. After manufacture of a block mould and casting of cast steel in con-ventional manner, the cast mould is allowed to cool until the casting has a temperature of between 200C and 500C. It is thereafter immersed into a bath with a temperature ~f 55C to --60C consisting of a three per cent sodium hydroxide solution.
After about five minutes the mould material has been broken down and the castings been exposed. - -.
A cast mould is manufactured in the manner described in Example 1. It is then poured over with a three per cent sodium hydroxide solution with a temperature of 55 to 60C. After a few minutes the mould material has been broken down and the castings been exposed~
~ -5-. ~ , .
8~L3:L `
Exam~le 3 A flask mould is manufactured of the same mould material as the one described in example 1. The mould after casting is immersed in an alkaline bath of the same kind as the one described in Example 1. Also in this case the mould material is broken down and the casting is exposed rapldly. Becau~e the cast mould is located in a flask, however, the breakdown and the exposure will require a somewhat longer time than Eor a block mould.
Example 4 A cast flask mould is manufactured in the manner described in Example 3. The mould is sprayed with an alkaline aqueous solution of the same kind as the one stated in Example 1 and with a pressure of about 5 atmospheres. Also in this case the mould material is broken down and the casting exposed rapidly.
. ~ ' ', ,.',:
Mould material which has been broken down according to any of the Examples 1 to 4 is rilled down into a container which is filled with water and which i5 continuously supplied with water by means of a sprinkling devlce at the bottom of the box.
The last-mentioned supply of water creates turbulence in the water and a continuous through flow of water. The water lea~es the container through a s~illway. The sand is washed during its passage through the water. The fine part o the mould material leaves the container through the spillway. The treatment is ` carried out so that the pH value in the water is maintained below 10. ~hen the washing is finished the sand is removed from container and dried in a sand drying plant. The sand thus regenerated is mixed to be re-~sed first with 0.4 per cent bywelght -5a- -~' :
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(calculated on the sand) of ester hardener consisting of equal parts of diacetin and triacetin and thereafter with 4 per cent by weight (calculated on the sand) of water glass containing 40 per cent by weight of silicate and 60 per cent by weight of water.
The mould material is applied to a pattern and is allowed to harden for 20 minutes, whereafter the pattern is drawn. ~fter a hardening time o~ 8 hours casting takes place and at the knock-out the material exhibits good surfaces and there are not tendencies to metal penetration.
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The method accordiny to the present invention is applicable for knocking out and regeneration of silicate-bonded mould materials for all kinds of castings such as cast iron, cast steel, light metals, bronzes, etc. According to the invention, particularly great advantages are obtained for cast steel.
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Particularly in the case of knock-out of cores the spray method may be valuable since removal of sand is normally more trouble-some with cores. A suitable pressure on the aqueous solution in the case of spraying may be from 1 to 50 atmospheres. If it is desirable at the same time to expose a metallic, pure surface on the castings, it may be necessary to use a higher pressure, for example from 50 to 300 atmospheres. For economical reasons the aqueous solution, after it has been used for pouring, sprinkling or spraying of the mould after casting and after it has been separated from the releasecl sand, should be recirculated to the knock-out equipment to be used for pouring, sprinkliny or spraying oE new cast moulds.
.
,:
'~
; ~ 2a -.
- ' : : - . - .:' .
The mould oE silicate-bonded mould material may be manufactured in conventional manner. Thus, the mould material may be manufactured from quartz sand, chromite sand, olivine sand or more other sand used within the casting technique.
~s binder Eor the sa~d there is prefer~ed water glass, but also other water-soluble silicates are possible to use, T~e amount of silicate that is added when preparing the mould material suit-ably is from 0.5 to 5 % of the weight of the sand. The sili-cate is normally added in the form of an aqueous solution~ In the amount of silicate mentioned above the water isnot included.
The hardening may be performed in any conventional manner, hardening with carbon dioxide and with organic ester being of particular importance, but hardening with other substances mixed into the mould material than organic ester, such as acids, cement, dicalcium silicaté and silicon, may be used as well.
Esters which are often used as hardeners are mixtures of diacetin (glyceryl diacetate) and triacetin ~lyceryl tria-cetate) or mixtures of diacetin and ethyl diglycol diacetate in various weight ratios depending on the desired hardening times. The esters mentioned may also be used separately. Also other estersmay be usedJ among other things acetates of glycol. ;-The amount of ester added to the sand when preparing the mould material suitably is from 0.05 to 2% of the weight of the sand.
When manufacturing a mould for ester hardening the mixture of the components may be carried out, for example, in a continuous screw mixer, sand and ester being normally mixed before the silicate is added, as mentioned earlier. Among other things, the mould can be manufactured by allowing the mould material, after mixing in the silicate, to run down over the pattern which ,."
is suitably vibrated or rammed. When the mould has been allowed to harden 15-30 minutes the pattern can be drawn. ~he top and bottom parts of the mould are then put togethe~ after a few ~, ... , . - . ~ - , '~ ' :~7~ 3~
additional hours o~ hardening. Casting is usually performed after six hours at the earliest. casting may be performed, for example, from a bottom-discharging ladle. Any cores used can be manufactured in a corresponding manner, if desired. When the castin~ has cooled, the cast mould is treated with the alkaline aqueous solution in accordance wi~h the present inven-tion.
The alkaline aqueous solution can be produced by dissolv-ing sodium hydroxide, potassium hydroxide and/or another alkali 10 metal hydroxide and/or ammonia in water. Other substances than -those mentioned giving aqueous solutions with sufficient alkali-. ~.
nity may, of course, be used as well. The pH value of the aqueous solution suitably amounts to at least 12, and preferably to at least 13. When using alkali metal hydroxide to achieve the alkalinity the amount of alkali metal hydroxide should be at least 0.4 %, suitably 0.4 to 20 % and preferably 0.4 to 10 % -of the total weight of hydroxide and water. When using ammonia there is preferred an amount of 10 to 30 % of the total weight -of ammonia and water. ~
::
An increase of the temperature of the aqueous solution improves the break down markedly. In particular if there are .
problems in breaking down themould material located adjacent to the castings and;therefore exposed to the most heat, it may be essential to raise the temperature of the aqueous solution. If such problems exist the use of a high content of alkali metal hydroxide in the aqueous solution is also recommended~ The ;
temperature of the aqueous solution is suitably at least 40C
and suitably at the most 100C, preferably 50 to 80C. The treatment is normally carried out at atmospheric pressure for a time o~ from one minute to one hour.
When the castings have been exposed from the mould material they are made clean by water, for example by washing or rinsing.
- ~07~3~3~
The mould material broken down in the form of sand contaminated with alkali metal hydroxide can be used after -cleaning - consisting in repeated rinsing with water and subsequent drying - for manufacturing a new mould material, i.e. the mould material can be re-used. When using ester hardeners, ester is first mixed into the cleaned mould material, as described earlier~ and then water glass or anotller silicate binder. The mould material is thereaEter ready for manufacture of new moulds.
Embodiments of the invention are described in the follow-ing examples.
Exa~ple 1 A mould material is manufactured of quartz sand with a medium grain size of 0.25 mm. The sand is first mixed with 0.4 per cent by weight (calculated on the sand) of an ester hardener consisting of a mixture of equal parts of diacetin and triacetin and thereafter with 4 per cen~ by weight (calcul~
- ated on the sand) of water glass containing 40 per cent by weight of silicate and 60 per cent by weight of water. After manufacture of a block mould and casting of cast steel in con-ventional manner, the cast mould is allowed to cool until the casting has a temperature of between 200C and 500C. It is thereafter immersed into a bath with a temperature ~f 55C to --60C consisting of a three per cent sodium hydroxide solution.
After about five minutes the mould material has been broken down and the castings been exposed. - -.
A cast mould is manufactured in the manner described in Example 1. It is then poured over with a three per cent sodium hydroxide solution with a temperature of 55 to 60C. After a few minutes the mould material has been broken down and the castings been exposed~
~ -5-. ~ , .
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Exam~le 3 A flask mould is manufactured of the same mould material as the one described in example 1. The mould after casting is immersed in an alkaline bath of the same kind as the one described in Example 1. Also in this case the mould material is broken down and the casting is exposed rapldly. Becau~e the cast mould is located in a flask, however, the breakdown and the exposure will require a somewhat longer time than Eor a block mould.
Example 4 A cast flask mould is manufactured in the manner described in Example 3. The mould is sprayed with an alkaline aqueous solution of the same kind as the one stated in Example 1 and with a pressure of about 5 atmospheres. Also in this case the mould material is broken down and the casting exposed rapidly.
. ~ ' ', ,.',:
Mould material which has been broken down according to any of the Examples 1 to 4 is rilled down into a container which is filled with water and which i5 continuously supplied with water by means of a sprinkling devlce at the bottom of the box.
The last-mentioned supply of water creates turbulence in the water and a continuous through flow of water. The water lea~es the container through a s~illway. The sand is washed during its passage through the water. The fine part o the mould material leaves the container through the spillway. The treatment is ` carried out so that the pH value in the water is maintained below 10. ~hen the washing is finished the sand is removed from container and dried in a sand drying plant. The sand thus regenerated is mixed to be re-~sed first with 0.4 per cent bywelght -5a- -~' :
~', '...
. :-.- .:: ~ . . ... . . .. .
8~3~
(calculated on the sand) of ester hardener consisting of equal parts of diacetin and triacetin and thereafter with 4 per cent by weight (calculated on the sand) of water glass containing 40 per cent by weight of silicate and 60 per cent by weight of water.
The mould material is applied to a pattern and is allowed to harden for 20 minutes, whereafter the pattern is drawn. ~fter a hardening time o~ 8 hours casting takes place and at the knock-out the material exhibits good surfaces and there are not tendencies to metal penetration.
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The method accordiny to the present invention is applicable for knocking out and regeneration of silicate-bonded mould materials for all kinds of castings such as cast iron, cast steel, light metals, bronzes, etc. According to the invention, particularly great advantages are obtained for cast steel.
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Claims (9)
1. A method of knocking out silicate-bonded granular mould material from a mould after casting, characterized in that the mould after casting is contacted with an alkaline aqueous solution to loosen the bond between the grains by dissolving the silicate binder, and release the mould material.
2. Method according to claim 1, characterized in that the mould after casting is immersed in or poured over or sprayed or sprinkled with the alkaline aqueous solution.
3. Method according to claim 1, characterized in that the aqueous solution has a pH value of at least 12.
4. Method according to claims 1, 2 or 3, characterized in that the aqueous solution has been made alkaline with an alkali metal hydroxide.
5. Method according to claims 1, 2 or 3, characterized in that the aqueous solution has been made alkaline with ammonia.
6. Method according to claims 1, 2 or 3, characterized in that the aqueous solution contains at least 0.4 per cent by weight of an alkali metal hydroxide.
7. Method according to claims 1, 2 or 3, characterized in that the temperature of the aqueous solution amounts to at least 40°C.
8. Method according to claims 1, 2 or 3, characterized in that the aqueous solution is removed from the granular mould material recovered from a knocked-out mould to make it reusable for the manufacture of new moulds and/or cores.
9. Method according to claims 1, 2 or 3, characterized in that the aqueous solution is removed from the granular mould material recovered from a knocked-out mould to make it reusable for the manufacture of new moulds and/or cores and the knocked-out granular mould material is washed with water until the pH value of the washing water has dropped to 10 at the most.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7507435A SE398829B (en) | 1975-06-30 | 1975-06-30 | KIT FOR KEEPING OUT OF THE SILICATE-BONDED MASS PASS |
| SE7512964A SE414601B (en) | 1975-11-18 | 1975-11-18 | SET FOR MOLDING OF THE SILICATE BOTTOM FORMASSA UR PAGJUTEN FORM |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1078131A true CA1078131A (en) | 1980-05-27 |
Family
ID=26656629
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA255,890A Expired CA1078131A (en) | 1975-06-30 | 1976-06-28 | Method for knocking out silicate-bonded mould material from a mould after casting |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS526338A (en) |
| CA (1) | CA1078131A (en) |
| DE (1) | DE2626224C2 (en) |
| DK (1) | DK153527C (en) |
| FI (1) | FI61648C (en) |
| FR (1) | FR2316024A1 (en) |
| GB (1) | GB1549220A (en) |
| NO (1) | NO142203C (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55114457A (en) * | 1979-02-27 | 1980-09-03 | Hitachi Ltd | Core removing method |
| DE3537351A1 (en) * | 1985-10-19 | 1987-04-23 | Thyssen Industrie | Method and device for removing a ceramic core from a cast element |
| US5678583A (en) * | 1995-05-22 | 1997-10-21 | Howmet Research Corporation | Removal of ceramic shell mold material from castings |
| US6241000B1 (en) * | 1995-06-07 | 2001-06-05 | Howmet Research Corporation | Method for removing cores from castings |
| US7216691B2 (en) | 2002-07-09 | 2007-05-15 | Alotech Ltd. Llc | Mold-removal casting method and apparatus |
| JP2005532911A (en) | 2002-07-11 | 2005-11-04 | コンソリデイテッド エンジニアリング カンパニー， インコーポレイテッド | Method and apparatus for assisting removal of sand mold from castings |
| WO2004024357A1 (en) | 2002-09-11 | 2004-03-25 | Alotech Ltd. Llc. | Chemically bonded aggregate mold |
| CA2496791A1 (en) | 2002-09-20 | 2004-04-01 | Alotech Ltd. Llc | Lost pattern mold removal casting method and apparatus |
| US7121318B2 (en) | 2002-09-20 | 2006-10-17 | Alotech Ltd. Llc | Lost pattern mold removal casting method and apparatus |
| US8763247B2 (en) * | 2010-10-06 | 2014-07-01 | GM Global Technology Operations LLC | Diesel piston with bi-metallic dome |
| US8813357B2 (en) | 2010-10-06 | 2014-08-26 | GM Global Technology Operations LLC | Piston with bi-metallic dome |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE364227C (en) * | 1922-03-18 | 1922-11-18 | Fritz Wuest Dr | Process for cleaning castings |
| US3044087A (en) * | 1959-11-17 | 1962-07-17 | Powers Alex | Apparatus for eliminating ceramic cores |
| US3563711A (en) * | 1968-07-18 | 1971-02-16 | Trw Inc | Process for removal of siliceous cores from castings |
| US3698467A (en) * | 1971-01-04 | 1972-10-17 | United Aircraft Corp | Method of removing silaceous cores from nickel and cobalt superalloy castings |
-
1976
- 1976-06-11 DE DE2626224A patent/DE2626224C2/en not_active Expired
- 1976-06-24 FI FI761846A patent/FI61648C/en not_active IP Right Cessation
- 1976-06-28 NO NO762234A patent/NO142203C/en unknown
- 1976-06-28 CA CA255,890A patent/CA1078131A/en not_active Expired
- 1976-06-28 JP JP51076299A patent/JPS526338A/en active Pending
- 1976-06-29 DK DK292876A patent/DK153527C/en not_active IP Right Cessation
- 1976-06-29 GB GB26974/76A patent/GB1549220A/en not_active Expired
- 1976-06-30 FR FR7619880A patent/FR2316024A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FI61648B (en) | 1982-05-31 |
| DE2626224A1 (en) | 1977-02-03 |
| DK292876A (en) | 1976-12-31 |
| DE2626224C2 (en) | 1985-01-03 |
| FR2316024B1 (en) | 1982-04-02 |
| DK153527C (en) | 1988-11-28 |
| JPS526338A (en) | 1977-01-18 |
| GB1549220A (en) | 1979-08-01 |
| NO762234L (en) | 1977-01-03 |
| FI61648C (en) | 1982-09-10 |
| DK153527B (en) | 1988-07-25 |
| FI761846A7 (en) | 1976-12-31 |
| NO142203B (en) | 1980-04-08 |
| NO142203C (en) | 1980-07-16 |
| FR2316024A1 (en) | 1977-01-28 |
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