CN101850401A - Fired mold and precision casting process utilizing same - Google Patents

Abstract

The invention discloses a fired mold, which comprises a trumpet casting body, a mold head connected with the bottom end of the casting body and a plurality of cast bodies. The mold head is a cylinder of which the cross section is polygonal; the number of the cast bodies is the same as the edge number of the bottom of the mold head; all the cast bodies are uniformly distributed around the casting body; and the bottom of each cast body is opposite to one side wall of the mold head and is connected with the side wall through bridging. The invention also discloses a precision casting process by utilizing the fired mold. The bridge of the fired mold is connected with the bottom of the cast bodies, so metal fluid flows to the top from the bottom of a shell, the casting is full, the air exhaust is full, the one-time casting yield is improved by 20 percent, the cast product has good quality, and the qualification rate is 98 percent.

Description

A kind of fusible pattern and utilize the precision casting process of this fusible pattern

Technical field

The present invention relates to the precision casting technology field, relate in particular to a kind of fusible pattern and utilize the precision casting process of this fusible pattern.

Background technology

Model casting (hot investment casting) claims " lost-wax casting " again, typically refer at fusible material and make apperance, coat the several layers refractory material on the apperance surface and make shell, again shell is discharged in the apperance fusing, thereby obtain the casting mold of no die joint, after high-temperature roasting, get final product the founding method of back-up sand cast.Because apperance extensively adopts wax material manufacturing, so often model casting is called " lost-wax casting ".

First operation that model casting is produced is made fusible pattern exactly, and fusible pattern is the model that is used for forming fire-resistant shell, so will obtain dimensional accuracy and the high foundry goods of surface smoothness, at first fusible pattern itself just should have high dimensional accuracy and surface smoothness.It is simple that the performance of fusible pattern itself also should make operations such as system shell subsequently as far as possible in addition.For obtaining the fusible pattern of above-mentioned high-quality requirement, except good die mould (mould of fusible pattern injection) should be arranged, also must select suitable pattern-making material (being called for short the mould material) and rational mould making process.

The performance of pattern-making material singly should not guarantee to make easily the accurate and surface smoothness height of size, and intensity is good, lightweight fusible pattern, and it also should be the manufacturing of shell and obtains good foundry goods and creates conditions.The mould material is generally used wax material, natural resin and plastics (synthetic resin) preparation.All mould material of mainly preparing with wax material are called cerul mould material, and their fusing point is lower, is 60～700 ℃; All mould material of mainly preparing with natural resin are called resin basic mode material, and fusing point is high slightly, about 70～1200 ℃.

Be to make shell after fusible pattern completes, it generally is with behind the module dip-coating fireproof coating, sprinkles material shape refractory material, drying, sclerosis again, repeated multiple times like this, the fire-resistant extension layer that is coated with is reached till the thickness that needs, so just formed the multilayer shell on module, nearly it parks a period of time usually, it is fully hardened, the molten then module that loses just obtains the multilayer shell, is to cast at last.

Existing tubular cast, particularly snap joint, its fusible pattern generally are made up of the bar shaped die head of flaring pour mass, level and the casting body of die head below, are provided with two beam bodies between die head and the edge, casting body top, and die head is connected with the pour mass bottom.The multilayer shell that utilizes the fusible pattern of shape like this to make, the cast chamber is positioned at the top, and the die head chamber is positioned at the centre position, and the foundry goods chamber is positioned at the bottom, and during casting, metal fluid foundry goods top of chamber flows to the bottom, often cause underpriming, meet air in the casting process and produce pore, foundry goods needs post processing.When melting fusible pattern in addition, the fusing earlier that wall is thin, the back fusing of wall thickness, because the thin part of the fusible pattern wall of traditional snap joint is in the bottom, the wall thickness part is at the top, and thin part is at the top during demoulding, the wall thickness part causes the bottom shell to expand in the bottom, cracking.

Summary of the invention

The invention provides a kind of fusible pattern that is used to cast tubular cast, solved conventional tube casting pouring deficiency, ventilation has some setbacks, the problem that product percent of pass is low.

A kind of fusible pattern, comprise the pour mass of trumpet type, the die head that is connected with the pour mass bottom and some casting bodies, described die head is the cylinder that cross section is regular polygon, described casting body quantity is identical with limit, the bottom surface number of die head, all casting bodies evenly distribute around pour mass, and each casting body bottom is connected with it over against a side sidewall of die head and by putting up a bridge.

Described tubular cast is snap joint.

Described pour mass and casting body spacing are 1～2: 5 with the ratio of the maximum outside diameter of casting body, can satisfy the heat radiation requirement, promote casting quality.

The bridging of described each foundry goods by 3～5 levels is connected with a side sidewall of die head, bridging quantity very little, poring rate is slow, then increases manufacture difficulty and cost too much.

The quantity of described casting body is 3, and die head is a triangular prism, and foundry goods quantity is too much, and it is bad then to dispel the heat, and foundry goods quantity production efficiency at least is low.

Set up the exhaust body between the edge, top of edge, described casting body top and pour mass, improved the cast exhaust capacity.

The feeding body that forms trumpet type is radially expanded in described pour mass bottom, can realize automatic feeding.

The present invention also provides a kind of shell that utilizes above-mentioned fusible pattern to make.

The present invention provides a kind of accurate casting process that utilizes above-mentioned fusible pattern again, may further comprise the steps:

In fusible pattern surface dip-coating slurry, stucco, dry solidification, the repeatable operation several times, the demoulding makes shell and carries out roasting, is the inner chamber of 1100～1120 ℃ molten steel injection shell with temperature, cooling, shelling.

Described slurry is made up of binding agent and refractory material, sand is merely refractory material, and refractory material can be quartzy and corundum and alumina silica refractory, as fire clay, aluminium vanadine, flint clay etc., binding agent is selected siliceous colloid solution for use, as silicate hydrolyzate liquid, waterglass and Ludox etc.

The bridging of fusible pattern of the present invention is connected with the foundry goods bottom, and metal fluid flows to the top from the bottom of shell when making cast, and not only cast is abundant, and can fully carry out exhaust, and one time yield rate has improved 20%, and casting quality is better, and qualification rate is up to 98%.

Description of drawings

Fig. 1 is the structural representation of fusible pattern of the present invention;

Fig. 2 is the structural representation of fusible pattern pour mass of the present invention and die head.

The specific embodiment

As shown in the figure, a kind of fusible pattern that is used to cast snap joint, pour mass 1, pour mass 1 bottom that comprises trumpet type radially expanded gradually downwards and formed a feeding body 5, and connect the die head 2 of a triangular column type, and being provided with 3 around the pour mass 1 around its equally distributed casting body 3, the shape of die head 2 and the quantity of casting body 3 can change certainly, but must satisfy die head 2 is that cross section is the cylinder of just changeable shape, to guarantee that casting body 3 evenly distributes, make their heat radiations evenly, the product indifference.

Casting body 3 is identical with the snap joint shape that will cast, and casting body 3 also can be other shape certainly.When it was tubulose, length was at 10～50cm, and external diameter is at 5～30cm, and cross sectional shape can be any, and the spacing between pour mass 1 and casting body 3 outer walls and the ratio of the maximum outside diameter of casting body 3 are generally 1～2: 5, and cost is lower, and heat radiation is very fast.

Be provided with the bridging 6 of 3 levels between the bottom of the sidewall of die head 2 and each casting body 3, the quantity of bridging 6 can be adjusted according to the size of actual foundry goods, generally at 3～5.In order to improve exhaust capacity, set up the exhaust body 6 of direct rod shape between the edge, top of casting body edge, 3 top and pour mass 1.

At above-mentioned fusible pattern surface dip-coating slurry, stucco then, dry solidification, so repeated multiple times operation places a period of time to make its curing, inserts at last in the demoulding still with the high-temperature steam dewaxing, makes shell.Pour mass 1, casting body 3, bridging 6, exhaust body 4, feeding body 5 and die head 2 form cast chamber, foundry goods chamber, cast passage, steam vent, feeding chamber and die head chamber respectively in shell.In the dewaxing process, because fusible pattern is inverted, casting body 3 bottom wall thickness melt earlier, top wall thin back fusing, and therefore, shell inside does not have the wax accumulation and expands, thus crowded bad shell.

Shell completes and just can pour into a mould after roasting, molten steel is poured into shell inside from the cast top of chamber, molten steel is up walked from the bottom in foundry goods chamber through the cast passage, gas can be discharged from steam vent smoothly, can not cause underpriming, can not produce pore yet, finally make product quality and qualification rate increase substantially.

The present embodiment fusible pattern adopts cerul mould material to make, and can reclaim after the dewaxing, and slurry is made up of quartz sand and silester, and liquid steel temperature is 1100 ℃, and yield rate of final casting is 65.2%, and qualification rate is 98%.And utilize traditional fusible pattern to cast, one time yield rate only is 47.2%

The liquid steel temperature of another embodiment cast is 1120 ℃, and yield rate of final casting is 67.6%, and qualification rate is 97%, utilizes traditional fusible pattern to cast, and one time yield rate is 48.3%.By above-mentioned example as can be known, utilize fusible pattern of the present invention to carry out hot investment casting, one time yield rate can improve 20%.

Claims (8)

1. fusible pattern, comprise the pour mass (1) of trumpet type, die head (2) and the some casting bodies (3) that is connected with pour mass (1) bottom, it is characterized in that: described die head (2) is the cylinder of regular polygon for cross section, described casting body (3) quantity is identical with limit, the bottom surface number of die head (2), all casting bodies (3) evenly distribute around pour mass (1), and each casting body (1) bottom is connected with it over against a side sidewall of die head (2) and by put up a bridge (6).

2. fusible pattern according to claim 1 is characterized in that: be provided with 3～5 bridging (6) between described each casting body (3) bottom and the die head.

3. fusible pattern according to claim 1 is characterized in that: the quantity of described casting body (3) is 3, and die head (2) is a triangular prism.

4. fusible pattern according to claim 1 is characterized in that: set up exhaust body (4) between the edge, top of edge, described casting body (3) top and pour mass (1).

5. fusible pattern according to claim 1 is characterized in that: the feeding body (5) that forms trumpet type is radially expanded in described pour mass (1) bottom.

6. fusible pattern according to claim 1 is characterized in that: described casting body (3) is a tubulose.

7. fusible pattern according to claim 6 is characterized in that: described pour mass (1) is 1～2: 5 with the ratio of the maximum outside diameter of casting body (3) spacing and casting body (3).

8. precision casting process that utilizes the described fusible pattern of claim 1 may further comprise the steps:

In fusible pattern surface dip-coating slurry, stucco, dry solidification, the repeatable operation several times, the demoulding makes shell and carries out roasting, is the inner chamber of 1100～1120 ℃ molten steel injection shell with temperature, cooling, shelling.

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