CN104308086A

CN104308086A - Large-sized hollow urea core for investment casting and manufacturing process of large-sized hollow urea core

Info

Publication number: CN104308086A
Application number: CN201410604082.0A
Authority: CN
Inventors: 孔辉
Original assignee: Guizhou Anji Aviation Precision Casting Co Ltd
Current assignee: Guizhou Anji Aviation Precision Casting Co Ltd
Priority date: 2014-10-31
Filing date: 2014-10-31
Publication date: 2015-01-28
Anticipated expiration: 2034-10-31
Also published as: CN104308086B

Abstract

The invention provides a large-sized hollow urea core for investment casting and a manufacturing process of the large-sized hollow urea core. The shape of the large-sized hollow urea changes with needs of each casting to form a hollow groove-shaped structure; the thickness of the wall is 2-10 cm. The large-sized hollow urea core has the benefits that 1) the process is simplified, 2) the production efficiency of the casting is improved, 3) the production cost of investment of large-sized equipment is reduced, and 4) the risk of uncertain factors of quality brought by complex processes is reduced.

Description

A kind of for investment pattern precision casting in large hollow urea core and manufacture craft

Technical field

The invention belongs to investment pattern precision casting field, particularly relate to a kind of for investment pattern precision casting in large hollow urea core and manufacture craft.

Background technology

Precision-investment casting is in sector application wide range such as Aeronautics and Astronautics, weapons, electronics, boats and ships, also known as " lost-wax casting ", normally coat several layers of refractory material on wax-pattern surface, after its dry through, molten the going of wax-pattern is wherein made shell, then through roasting, then pour into a mould, and obtain a kind of method of foundry goods, because the foundry goods obtained has higher dimensional accuracy and surface smoothness, therefore also known as " precision-investment casting "; The maximum advantage of model casting is exactly because investment-casting has very high dimensional accuracy and surface smoothness, so can machining operations be reduced, just on part, require that a little allowance is stayed at higher position, even some foundry goods only stays polishing, polishing surplus, need not machining can use; As can be seen here, adopt investment casting method can save machine tool and machining period in a large number, significantly save raw material metal.

In recent years, tubular cast particularly macrotype tubular foundry goods gets more and more, casting difficulty is also increasing, solid urea core is mostly adopted to carry out wax-pattern compacting in this case, because tubular cast size is large, and then cause the consumption of urea core large, and in this situation, urea core cooling velocity is slow, production efficiency is low, increases cost.

Summary of the invention

For solving the problems of the technologies described above, the invention provides a kind of for investment pattern precision casting in large hollow urea core and manufacture craft, the large hollow urea core in this investment pattern precision casting be used for and manufacture craft thereof are passed through

The present invention is achieved by the following technical programs.

Provided by the invention a kind of for investment pattern precision casting in large hollow urea core, the shape of described large hollow urea core needs change along with each foundry goods, and it is the channel-shaped structure of a hollow, and the thickness of its wall is 1 ~ 10cm, preferably 1 ~ 5cm, is more preferably 1 ~ 2cm.

The making raw material of described large hollow urea core is urea, and adds 0.1 ~ 4% boric acid and 0.01 ~ 1% ethyl silicate hydrolyzate in urea, is preferably 1 ~ 4% boric acid and 0.1 ~ 0.5% ethyl silicate hydrolyzate.

Present invention also offers a kind of for investment pattern precision casting in its manufacture craft of large hollow urea core, in comprising the following steps:

(1) the shell mould of the hollow structure of tubular cast is made of wax-pattern;

(2) urea is placed on vessel in heating and makes urea liquid to 130 ~ 140 DEG C, then boric acid and ethyl silicate hydrolyzate are added in urea liquid;

(3) urea liquid is poured in shell mould, and with glass bar stir, condensed on shell mould inner wall one deck urea time, remaining urea liquid is poured out;

(4) molding is got core, is revised urea core and dry urea core.

Wherein in step (3), pour into after shell mould until urea, the temperature of shell mould is controlled below 35 DEG C, be preferably less than 30 DEG C.

The method of described control shell mould adopts recirculated water to flow, under making shell mould remain on determined temperature at the outer surface of shell mould.

Beneficial effect of the present invention is: 1) technique simplifies; 2) the production efficiency rate of foundry goods is improved; 3) production cost needing to drop into main equipment is reduced; 4) the quality uncertain factor risk that complicated technology brings is reduced.

Accompanying drawing explanation

Fig. 1 is use schematic diagram of the present invention

In figure: 1-urea figure.

Detailed description of the invention

Further describe technical scheme of the present invention below, but described in claimed scope is not limited to.

Provided by the invention a kind of for investment pattern precision casting in large hollow urea core, the shape of described large hollow urea core needs change along with each foundry goods, it is the channel-shaped structure of a hollow, the thickness of its wall is 1 ~ 10cm, preferably 1 ~ 5cm, be more preferably 1 ~ 2cm, and, in order to ensure to keep its indeformable or damage at urea core wall enough thin, simultaneously when needs dissolved urea core, dissolve fast, be add 0.1 ~ 4% boric acid and 0.01 ~ 1% ethyl silicate hydrolyzate in urea at the making raw material of large hollow urea core, be preferably 1 ~ 4% boric acid and 0.1 ~ 0.5% ethyl silicate hydrolyzate, increase the caking property between urea molecule.Because urea core is hollow, its thawing time then has solid being about reduced to for several hours only to need 20 ~ 30 minutes, as rested in water, or often water is stirred, the most handy circulating water, not only make urea dissolution time accelerate, and avoid cere to make the saponification of cere inwall in the urea liquid in high concentration, affect the surface quality of foundry goods.

(1) make the shell mould of the hollow structure of tubular cast of wax-pattern, carefully must check mould before coremaking, guarantee that mould is intact, after guaranteeing that mould can normally use, at die cavity; Inside brush parting agent, parting agent must be brushed evenly, and parting agent adopts the transformer oil of 100%;

(2) urea is placed in stainless-steel pan is heated to 130 ~ 140 DEG C and makes urea liquid, do not heat up during heating too fast, too high, to prevent the urea solution when releasing ammonia from splashing, then boric acid and ethyl silicate hydrolyzate are added in urea liquid,

(3) urea liquid is poured in shell mould, the temperature of shell mould is controlled below 35 DEG C, be preferably less than 30 DEG C, and stir with glass bar, condensed on shell mould inner wall one deck urea time, remaining urea liquid is poured out, and the method for described control shell mould adopts recirculated water to flow, under making shell mould remain on determined temperature at the outer surface of shell mould;

(4) core is got in molding, enters and firmly wants evenly, and hit mould twice with wooden mallet, to prevent urea core to be out of shape, clear up, avoid mold-locked for the urea on fractal area during molding.

(5) revise urea core, will repair after molding to the burr in urea core, fleshiness, overlap and pore, too much for blemish, the defect that cannot repair, must not use, scrap;

(5) dry urea core, the urea core trimmed is placed on dry place and carries out natural air drying.

In the present invention, its feature has 3, as follows:

(1) urea core is designed to hollow, had both saved the cost of production urea core, and decreased the dissolution time of urea core simultaneously, decrease production cost, add operating efficiency '

(2) improve on the raw material making urea core, boric acid and ethyl silicate hydrolyzate is added in urea, the effect adding boric acid is the dissolution time that quickening urea core needs when dissolving, the effect adding ethyl silicate hydrolyzate increases the caking property between urea granules, because the general of ethyl silicate hydrolyzate is used in formwork making as binding agent, so design in the scope of 0.01 ~ 1% at the addition of urea core, the caking property between urea granules can not only be ensured, and can ensure that urea core can be dissolved soon when dissolving.

(3) in the manufacturing process of urea core, flow at shell mould outer surface with the running water of flowing, ensure that the temperature of shell mould can control in good scope, ensure that the surface of the urea mould made is more smooth, smooth.

Our factory is " bend pipe " foundry goods (see Fig. 1) that certain company produces, and this foundry goods belongs to macrotype tubular foundry goods, and wherein center is urea core (1).Adopt solid urea core coremaking before improving, urea core consumption is large, and cool time is long, and add difficulty in operating process, production efficiency is low.Adopt hollowing technology after improvement, the consumption of urea core reduces greatly, also reduces to original 1/7 cool time, well improves production efficiency, reduce cost.

Claims

1. one kind for investment pattern precision casting in large hollow urea core, it is characterized in that: the shape of described large hollow urea core needs change along with each foundry goods, and it is the channel-shaped structure of a hollow, and the thickness of its wall is 1 ~ 10cm, preferably 1 ~ 5cm, is more preferably 1 ~ 2cm.

2. as claimed in claim 1 for investment pattern precision casting in large hollow urea core, it is characterized in that: the making raw material of described large hollow urea core is urea, and in urea, add 0.1 ~ 4% boric acid and 0.01 ~ 1% ethyl silicate hydrolyzate, be preferably 1 ~ 4% boric acid and 0.1 ~ 0.5% ethyl silicate hydrolyzate.

3. as claimed in claim 1 for investment pattern precision casting in its manufacture craft of large hollow urea core, it is characterized in that comprising the following steps:

(4) molding is got core, is revised urea core and dry urea core.

4. as claimed in claim 3 for investment pattern precision casting in its manufacture craft of large hollow urea core, it is characterized in that: in step (3), pour into after shell mould until urea, the temperature of shell mould is controlled below 35 DEG C, be preferably less than 30 DEG C.

5. as claimed in claim 4 for investment pattern precision casting in its manufacture craft of large hollow urea core, it is characterized in that: the method for described control shell mould adopts recirculated water to flow, under making shell mould remain on determined temperature at the outer surface of shell mould.