CN1270846C - Forming block for disk casting production and process for production of casting therewith - Google Patents

Abstract

The present invention relates to a molding die for production of disc castings and a process for producing castings using the same. The metal mold is used as a lower mold, the sand mold is used as an upper mold, and positioning pins and sand filling grooves are designed on the lower mold of the metal mold. Its casting production process includes sand-making upper mold-taking mold-metal lower mold spraying paint-metal lower mold preheating-core lowering, box closing-pouring. The mold of the present invention makes full use of the advantages of sand mold and metal mold casting process, so that the casting process is easy to operate, does not need special casting equipment (such as low-pressure casting equipment), the process parameters are easy to control, the casting quality is stable, and the casting internal quality and dimensional accuracy are relatively high. High, the casting quality is almost close to the metal casting quality.

Description

Forming molds for the production of disc castings and the process for producing castings using them

technical field

The invention belongs to the technical field of casting, and in particular relates to a casting casting forming process and a forming mold used therefor.

technical background

Sand casting produces disc castings. There are many process factors that affect the quality of castings. The process conditions are not easy to control. There are many casting defects. Equipment maintenance costs are high, process parameters and mold adjustments are cumbersome, the development cycle is long, and production costs are high. Using metal mold casting technology, the shape of the metal mold is complex, the cycle of mold production and adjustment is long, and the production cost is also high; at the same time, due to the poor air permeability and yield of the metal mold, it is more difficult to adjust the mold design, production and casting process parameters , and the production cost is also higher.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, to provide a disc casting forming mold, using a metal mold as the lower mold, and a sand mold as the upper mold, making full use of the advantages of sand mold and metal mold casting technology; The process of mold casting disc castings is easy to operate, does not require special casting equipment (such as low-pressure casting equipment), the process parameters are easy to control, the quality of castings is stable, the internal quality and dimensional accuracy of castings are high, and the quality of castings is almost close to that of metal castings. quality.

Technical solution of the present invention is as follows:

The forming mold for the production of disc castings uses a metal mold as the lower mold, a sand mold as the upper mold, and the sand mold adopts dry or resin sand mold.

Since the semi-metal casting needs to preheat the metal mold before pouring, the linear expansion of the metal mold is inevitable. In order to ensure the smooth closing of the box, it is necessary to test the metal mold from room temperature to the preheating temperature (approx. 400°C) linear expansion coefficient; according to our test results, the linear expansion of the metal mold is between 1.5‰ and 1.8‰ from the room temperature of about 25°C to the baking temperature of 400°C; the linear expansion coefficient passed the test is higher than that of the sand mold. The direction of the positioning pin hole is symmetrically expanded to a certain shape, and two elliptical positioning pin sleeves that are slightly larger than the positioning pins on the metal mold can also be designed, which are fixed on the upper mold of the sand mold during molding to ensure the smooth and smooth closing of the semi-metal mold. The box is positioned accurately.

The flow of molten metal in the gating system on the metal mold will cause the molten metal to be chilled in the gating system, so appropriate insulation measures should be designed to avoid a large loss of heat in the gating system. For this reason, we have designed a sand filling groove on the metal mold, which is located directly below the casting gating system. By pre-filling the water glass sand in the sand filling tank, the heat loss of the molten metal in the gating system can be reduced to ensure smooth filling of the molten metal, and it is also convenient to make the lower part of the lap sprue and place the filter.

The following is the process of producing disc castings using the above-mentioned semi-metal forming mold, which is divided into the following steps:

(1) Manufacture of resin sand upper mold: place the casting model and pouring system model on the metal lower mold respectively and position them, put on the sand box, fill resin sand to make resin sand upper mold;

(2) Take the mold: hang the mold on the resin sand and turn it over so that the mold is facing upwards, and take the casting model and the pouring system model;

(3) Spray paint under the metal mold;

(4) Preheating of the lower metal mold;

(5) Lowering the core and closing the box: take out the preheated metal mold, lower the core, and put the sand mold into the upper mold;

(6) Pouring, mold cooling, and box removal.

Technical effect of the present invention:

1. Compared with metal castings, semi-metallic castings obtained by the above-mentioned molds and their processes are almost as dense in structure and can achieve higher strength.

2. The process is simplified and the production efficiency is high. Since there is no need to make a lower mold, the operation of turning over the mold is saved, the same lower mold can be used repeatedly, and the processes of sand mixing, molding, and sand shakeout for the lower mold are also saved, so the production efficiency is significantly improved and labor is improved. condition.

3. The casting quality is stable. Because the semi-metal casting process is greatly simplified, the process factors affecting the quality of castings are reduced, and the process conditions are easier to control, so the quality of castings is stable and the scrap rate is greatly reduced.

4. Metal mold processing is difficult, the manufacturing and adjustment cycle is long, and the one-time investment is high. Using semi-metal molds, half of the simple shapes can be made into metal molds, and the more complex parts can be made into sand molds, which reduces the difficulty of metal mold processing and can significantly reduce the cost of metal molds. The manufacturing cost is shortened and the adjustment cycle is shortened, and the one-time investment is greatly reduced.

5. The exhaust condition of the metal mold is poor. The use of semi-metal mold casting can overcome this problem well. Using resin sand mold as the upper mold can not only meet the requirements of good air permeability of the mold, but also take advantage of the high strength and dimensional accuracy of the resin sand mold. With good characteristics, the dimensional accuracy of the produced castings can approach the level of metal mold casting.

6. Especially for the production of extra-large disc castings, it can obtain remarkable economic and social benefits.

Description of drawings

Fig. 1 is the structural diagram of semi-metal type molding die;

Fig. 2 is a schematic diagram of the metal mold of the mould;

FIG. 3 is a side view of FIG. 2 .

Detailed ways

See Fig. 1, Fig. 2 and Fig. 3 for the mechanism of the molding die used for the production of disc castings. It uses metal mold as the lower mold 1, and the sand mold as the upper mold 2. The sand mold adopts dry or resin sand mold, and 3 is the resin sand core. A positioning pin 4 and a sand filling groove 5 are designed on the lower mold of the metal mold, and the sand filling groove 5 is located directly below the gating system of the casting. The mold on the resin sand is provided with a positioning pin sleeve corresponding to the positioning pin.

Utilize above-mentioned mold to cast the technology of disc type casting:

(1) Manufacture of resin sand upper mold: place the casting model and pouring system model on the metal lower mold respectively and position them, put on the sand box, fill resin sand to make resin sand upper mold;

(2) Take the mold: hang the mold on the resin sand and turn it over so that the mold is facing upwards, and take the casting model and the pouring system model;

(3) Spray paint on the lower metal mold: preheat the lower metal mold to 200°C, and spray the paint;

(4) Preheating of the lower metal mold: the preheating temperature of the lower metal mold is 400°C, and the temperature is kept for 2-3 hours;

(5) Lowering the core and closing the box: Take out the preheated metal mold, lower the core, put the resin sand on the mold, place the gate type sprue cup, and tilt the mold at an angle of 3°-5°;

(6) For pouring, select different pouring temperatures according to the casting material, shape, and wall thickness.

After pouring, the casting mold is cooled, and the box is removed, and the above steps can be repeated for production when the lower mold of the metal mold is cooled below 40°C.

Claims (3)

1. dish class castings production mould, it is characterized in that its with metal mold as mo(u)ld bottom half, sand mold is as mo(u)ld top half, design on the described metal mold mo(u)ld bottom half have back-up sand groove, back-up sand groove be positioned at casting moulding system under, in fill out water-glass sand; Also designing on the metal mold mo(u)ld bottom half has alignment pin, is provided with set pin sleeve at the sand mold mo(u)ld top half corresponding to alignment pin, and set pin sleeve is the oval structure bigger slightly than alignment pin.

2. dish class castings production mould according to claim 1 is characterized in that sand mold adopts dryness or resin bonded sand mould.

3. utilize the technology of the described mould production of claim 1 dish class foundry goods, it is characterized in that the branch following steps:

(1) make the sand mold mo(u)ld top half: be placed on the metal mold mo(u)ld bottom half respectively cast model, running gate system model and the location, the cover cope, mo(u)ld top half is made in back-up sand;

(2) delivery: the type of codding mo(u)ld top half and upset, make model up, get cast model and running gate system model;

(3) metal mold mo(u)ld bottom half spray paint:

(4) metal mold mo(u)ld bottom half preheating:

(5) core, mould assembling down: the metal mold mo(u)ld bottom half that preheating is good takes out, and following core closes the sand mold mo(u)ld top half;

(6) cast, the casting mold cooling removes case.

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