CN102228954A - Lost foam casting technique capable of reducing deformation of mould piece joining seam - Google Patents

Abstract

The invention discloses a lost foam casting technique capable of reducing deformation of a mould piece joining seam. The technique comprises the following steps of: foaming and then injecting EPS (Expandable Polystyrene) or STMMA (Styrene-Methyl Methacrylate) bead particles into the cavity of a mould, forming first mould pieces by expansion, adhering each of the first mould pieces to form a first foam mould, finding jointing seam parts on the first foam mould which are not adhered firmly, forming bumps on the corresponding jointing seam parts in the cavity of the mould which are not adhered firmly; foaming and then injecting the EPS or STMMA bead particles into the cavity of a modified mould to obtain second mould pieces, forming recess structures on the parts of the second mould which are corresponding to the bumps, adhering each of the second mould pieces to form a second foam mould which is corresponding to a casting member in shape, adhering the second foam mould with a casting head mould to be a second mould cluster, coating the second mould cluster with paint, baking the second mould cluster; then burying the second mould cluster in free dry sand for jolt ramming; and next, casting molten metal to form the casting member. By using the casting technique in the invention, the problem of non-uniform thickness of the mould pieces by a method of hollowing the inside of the thick and large part of the mould is solved, so as to eliminate post-expansion featured as surface protrusion and to assist effective gluing of the mould pieces.

Description

A kind of lost foam casting process that reduces the distortion of matrix joint close

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Technical field:

The present invention relates generally to mould making process in the lost foam casting, relates in particular to a kind of lost foam casting process that reduces the distortion of matrix joint close.

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Background technology:

Lost foam casting is a kind of special casting technique.The first step is foaming, and promptly foaming machine adopts steam with the molding raw material that needs in EPS or about 30 times formation of the STMMA bead foaming amplification patternmaking process to use.Second step was molding, and promptly moulding equipment adopts steam to form matrix at the die cavity heating molding raw material of mould.The 3rd step was gummed or combination, if matrix can not directly form cast model, just needed bonding a plurality of matrixs to form cast model bunch together; Become whole with running gate system and cast model or cast model are bunch bonding again.The 4th step is with cast model or cast model bunch dip-coating oven dry.The 5th step, the cast model of oven dry or cast model bunch buried be placed on freely jolt ramming in the dry sand, casting of molten metal forms foundry goods again.The late expansion of rat often appears in matrix in the patternmaking process of lost foam casting; The consequence of this problem is that moulding does not meet drawing, or matrix when gummed forms the presentation of cracking at the joint close place.

Existing technology is to make disappearance mould model or matrix according to the size of drawing, generally can not reduce the figure paper size; But very easily produce late expansion for thick most matrix, thereby cause size not meet drawing or distortion.

Summary of the invention:

The object of the invention is exactly in order to remedy the defective of prior art, a kind of lost foam casting process that can reduce the distortion of matrix joint close to be provided.

The present invention is achieved by the following technical solutions:

A kind of lost foam casting process that reduces the distortion of matrix joint close is characterized in that: carry out according to the following steps successively:

One, with the die cavity of EPS or STMMA bead foaming back injection mould, under the effect of high-temperature steam, forms diaphragm one by expansion.

Two, with each matrix one bonding one-tenth of gummed bubble moulding model one corresponding, find the gummed seam position that does not cement on the bubble moulding model with the foundry goods shape.

Three, revise mould, corresponding unstuck gummed seam position is provided with bulge-structure in the die cavity with mould.

Four, with the die cavity of EPS or the amended mould of STMMA bead foaming back injection, form diaphragm two by expanding under the effect of high-temperature steam, matrix two forms sunk structure at the position of the described bulge-structure of correspondence.

Five, bubble moulding model two that each matrix two bonding one-tenth are corresponding with the foundry goods shape will steep moulding model two and dead head model and make up the bonding model cluster that becomes, and model cluster two is coated with coat, and oven dry is handled.

Six, the model cluster two after will drying places sandbox.

Seven, in sandbox, insert dry sand, sandbox is carried out three-dimensional vibrating make the dry sand consolidation.

Eight, vacuumize at sandbox top plastic covering film and to sandbox.

Nine, the zone at the casting of metals that will dissolve corresponding model cluster two places in the sandbox, model cluster two gasifications disappear, and metal replacement model cluster two after the condensation, obtains foundry goods.

The present invention is under the situation that does not influence casting structure, and the thick big position of corresponding foundry goods is provided with bulge-structure in the die cavity of mould, just forms corresponding sunk structure like this on matrix two, makes the inner hollow out of some thick major part at matrix die joint place like this; After composing model, still meet drawing; It is in uneven thickness that the method for the inner hollow out of the thick major part of this employing model solves matrix two, eliminates the late expansion of rat, helps matrix two and effectively glue together.

Advantage of the present invention is:

1. do not change the shape of model;

2. make matrix thickness uniformity as far as possible, also just make be heated with cool off consistent as far as possible;

3. reduce the area on plane, composition surface, also just reduce the composition surface cracking that inner late expansion causes.

4. reduce the consumption that EPS or STMMA produce material, reduce production costs.

The specific embodiment:

A kind of lost foam casting process that reduces the distortion of matrix joint close is characterized in that: carry out according to the following steps successively:

One, with the die cavity of EPS or STMMA bead foaming back injection mould, under the effect of high-temperature steam, forms diaphragm one by expansion.

Two, with each matrix one bonding one-tenth of gummed bubble moulding model one corresponding, find the gummed seam position that does not cement on the bubble moulding model with the foundry goods shape.

Three, revise mould, corresponding unstuck gummed seam position is provided with bulge-structure in the die cavity with mould.

Four, with the die cavity of EPS or the amended mould of STMMA bead foaming back injection, form diaphragm two by expanding under the effect of high-temperature steam, matrix two forms sunk structure at the position of the described bulge-structure of correspondence.

Five, bubble moulding model two that each matrix two bonding one-tenth are corresponding with the foundry goods shape will steep moulding model two and dead head model and make up the bonding model cluster that becomes, and model cluster two is coated with coat, and oven dry is handled.

Six, the model cluster two after will drying places sandbox.

Seven, in sandbox, insert dry sand, sandbox is carried out three-dimensional vibrating make the dry sand consolidation.

Eight, vacuumize at sandbox top plastic covering film and to sandbox.

The zone at the casting of metals that will dissolve corresponding model cluster two places in the sandbox, model cluster two gasifications disappear, and metal replacement model cluster two after the condensation, obtains foundry goods.

Claims (1)

1. one kind is reduced the lost foam casting process that the matrix joint close is out of shape, and it is characterized in that: carry out according to the following steps successively:

One, with the die cavity of EPS or STMMA bead foaming back injection mould, under the effect of high-temperature steam, form diaphragm one by expansion,

Two, with each matrix one bonding one-tenth of gummed bubble moulding model one corresponding, find the gummed seam position that does not cement on the bubble moulding model with the foundry goods shape;

Three, revise mould, corresponding unstuck gummed seam position is provided with bulge-structure in the die cavity with mould;

Four, with the die cavity of EPS or the amended mould of STMMA bead foaming back injection, form diaphragm two by expanding under the effect of high-temperature steam, matrix two forms sunk structure at the position of the described bulge-structure of correspondence;

Five, bubble moulding model two that each matrix two bonding one-tenth are corresponding with the foundry goods shape will steep moulding model two and dead head model and make up the bonding model cluster that becomes, and model cluster two is coated with coat, and oven dry is handled;

Six, the model cluster two after will drying places sandbox;

Seven, in sandbox, insert dry sand, sandbox is carried out three-dimensional vibrating make the dry sand consolidation;

Eight, vacuumize at sandbox top plastic covering film and to sandbox;

The zone at the casting of metals that will dissolve corresponding model cluster two places in the sandbox, model cluster two gasifications disappear, and metal replacement model cluster two after the condensation, obtains foundry goods.