CN1053129C

CN1053129C - Binder for casting loam core and producing method thereof

Info

Publication number: CN1053129C
Application number: CN97107343A
Authority: CN
Inventors: 龚林毕
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-01-21
Filing date: 1997-01-21
Publication date: 2000-06-07
Anticipated expiration: 2017-01-21
Also published as: CN1188695A

Abstract

The present invention belongs to a binder for casting loam cores and a production method thereof. The binder is prepared by taking starch as base materials, taking ammonia alum as a reinforcing agent, and adding dextrin to be mixed after the starch and the ammonia alum are gelatinized and softened. The binder has the advantages of facile raw materials, low cost, no harmful matters, no strict requirements for raw sand components in service, higher dry and wet strength, good ventilation property, quick baking and solidification, and low condemnation factor of the loam core. In addition, the present invention is favorable to improving casting quality and the environment of workshops, and the core sand can be recovered. Consequently, the disadvantages of high cost, low wet strength and large waste of core sand of a binder made from tung oil and the disadvantages of large environment pollution, high condemnation factor of the loam core, etc. of a binder made form casting synthetic fat are overcome.

Description

Binder for casting loam core and production method thereof

The invention belongs to preparation loam core binding agent in the casting technique, and the production method of this binding agent.This binding agent also can directly cooperate in order to preparation strength with roughing sand, and water content is less demanding, and the molding sand that need not dry; Also can make an addition in the cast paint to strengthen its adhesive force and to improve cast(ing) surface fineness.

At present, adopt tung oil, rape oil, rubber seed wet goods oiliness thing to make binding agent in the foundry industry traditionally, though it is good that this type of binding agent has a moisture resistance, the dry strength height, advantages such as the loam core resting period is long, but material source is difficulty, and cost is lower than higher and moist intensity, and loam core sand generally can only disposablely use; If add bentonite, though improved wet strength, the corresponding again decline of its dry strength makes the gas permeability in loam core descend simultaneously, and the percent defective of foundry goods rises.In order to overcome above-mentioned defective, someone has invented the binder for casting loam core of a kind of name of product " closing fat ", the leftover bits and pieces of this binding agent employing and vegetable oil, syrup, rosin, pitch and diesel oil, gasoline etc. are synthetic, therefore advantages such as this type of closes fat owing to have the raw material source extensively, and cost is lower are applied also better.But this type of closes fat and exists in the casting process flue gas big and certain toxicity arranged, pollute bigger to working environment, it is healthy to influence the workman, and loam core control to humidity in bake process of adopting this binding agent to make in addition requires defectives such as tighter, the scrappage height in loam core.

It is wide to the objective of the invention is to develop a kind of material source, the cost material is low, and the core binder of the good and nuisanceless pollution of result of use improves to reach that the loam core is done, wet strength and gas permeability, reduce flue gas and use cost in the casting process, avoid purposes such as environmental pollution.

The present invention adopts starch and dextrin to make the base stock of binding agent, utilizes caustic soda to make the paste agent of starch, adopts hydrogen peroxide as oxidant, and face adds ammonia alum to improve intensity and the hardness after solidify in the loam core.Therefore, the present invention includes water and binding agent base-material; Key is that this binding agent also comprises and contains the paste agent caustic soda, ammonia alum and hydrogen peroxide; And the binding agent base-material is starch and dextrin; In each composition by weight percentage; Water is 43～47%, starch 33～37%, and dextrin 14～18%, the caustic soda 2～3% of purity 95%, ammonia alum 0.8～1.2%, concentration is 33～35% hydrogen peroxide 1～1.5 ‰.Wherein starch both can be flour, also can be the corn kind of starch.

The production method of above-mentioned binding agent is, according to the above ratio:

A, at first water is contained in container, be heated to 60 °～65 ℃ and ammonia alum is soluble in water;

B, again starch is added and stir, end to there being powder ball, then,

C, caustic soda is slow, evenly adding make its abundant gelatinization;

D, add hydrogen peroxide again and carry out oxidation processes, it softeningly is pulpous state;

D, add dextrin at last, treat its fully molten even, the cooling back is existing.

The present invention adopts caustic soda as paste agent owing to adopt starch based material as the binding agent base-material, and ammonia alum is made reinforcing agent, therefore, does not contain hazardous substance in the whole prescription; In the use quality index such as roughing sand chemical analysis, clay content, water content are required not tight, raw material be easy to get and cost lower.The loam core of adopting binding agent of the present invention to make, after testing, when addition was 5%: wet breathable rate was 123, and dried air penetrability is 446; Green compression strength 0.033MPa, dry strength＞1.3MPa, baked tensile strength 0.48MPa, shearing strength 0.95MPa, gas forming amount 21.47m/g, surperficial stability 83.63%, collapsibility (residual resistance to compression) 0.024MPa.Therefore, adopt the present invention as core binder have good do, wet strength, baked and cured speed is fast, baked permeability, collapsibility are good, help improving casting quality, and the scrappage in loam core own are low; Cure and casting process in the stimulation flue gas that discharges out few, help improving the working environment of foundry again, add 50% advantages such as fresh sand use after the loam core sand after using in addition is recyclable.

Embodiment

Present embodiment is example: A, earlier water 45kg is added in the container to produce the 100kg binder for casting loam core, be heated to 60 °～65 ℃ after, ammonia alum 1kg added dissolves; B at the uniform velocity adds 36kg flour and stirs to no powder ball and ends; C is that 95% caustic soda 2.4kg slowly, evenly adds its abundant gelatinization then with purity; D, to add concentration again be that 33% hydrogen peroxide 120g is with the softening pulp of its pasty state; E adds dextrin at last to 100kg, treats to be finished product after molten even, the cooling.

Claims

1, a kind of binder for casting loam core comprises water and binding agent base-material; It is characterized in that this binding agent also comprises the paste agent caustic soda, ammonia alum and hydrogen peroxide; And the binding agent base-material is starch and dextrin; Each composition is by weight percentage: water is 43～47%, starch 33～37%, and dextrin 14～18%, the caustic soda 2～3% of purity 95%, ammonia alum 0.8～1.2%, concentration is 33～35% hydrogen peroxide 1～1.5 ‰.

2. by the described binder for casting loam core of claim 1, it is characterized in that described starch both can be flour, also can be the corn kind of starch.

3. by the production method of the described binder for casting loam core of claim 1, it is characterized in that according to the above ratio: A, at first water is contained in container, be heated to 60 °～65 ℃ and ammonia alum is soluble in water; B, again starch is added and stir, end to there being powder ball; Then, C, caustic soda is slow, evenly adding make its abundant gelatinization; D, add hydrogen peroxide again and carry out oxidation processes, it softeningly is pulpous state; E, add dextrin at last, treat its fully molten even, cooling back.