CN111673044A

CN111673044A - Sand-isolation chilled iron placing mode

Info

Publication number: CN111673044A
Application number: CN202010533973.7A
Authority: CN
Inventors: 宋亮; 纳建虹; 陈鹏; 缑鹏森
Original assignee: Kocel Machinery Co Ltd
Current assignee: Kocel Machinery Co Ltd
Priority date: 2020-06-15
Filing date: 2020-06-15
Publication date: 2020-09-18
Anticipated expiration: 2040-06-15
Also published as: CN111673044B

Abstract

The invention provides a sand-isolating cold iron placing method aiming at the problems that a grey iron casting is easy to shrink loose and has uneven hardness in the prior art, the quality requirements of uniform hardness and high hardness of the casting are realized through simple and feasible operation, the quality requirements of the casting are met, the cost is saved, and the production efficiency is improved. The machine tool body casting is made of gray iron, different matrix structures are obtained by changing the cooling speed of the thick-wall position of the guide rail so as to obtain the hardness of the guide rail which is expected to be obtained, the heat dissipation condition of the guide rail position can be improved by placing the chilling block, the solidification speed of the guide rail is accelerated, the temperature difference between the thick-wall guide rail position and other thin-wall positions is reduced, and the structure and the hardness are more uniform; meanwhile, the problem of color change after processing can be avoided.

Description

Sand-isolation chilled iron placing mode

Technical Field

The invention relates to a method for placing sand-isolated chilled iron of a casting.

Background

The casting is a processing mode of dissolving solid metal into liquid state, pouring the liquid metal into a casting mold with a specific shape, solidifying and forming the liquid metal, and in order to obtain the structural shape of the part, the structural shape of the part is made by other easily-formed materials in advance, and then a sand core is put into a sand mold, so that a cavity with the same structural size as the part is formed in the sand mold.

For thick-wall gray iron castings, the uniformity of the hardness of the castings is a very important problem, in order to meet the requirement of the hardness of guide rails of products, the grade of the material of the products is required to be improved to meet the requirement of the guide rails, and the material has the problems of high hardness and large stress at the position of a thin wall, is easy to shrink at the position of a hot spot and has uneven hardness at the position of the thick wall and the thin wall of the products. The method for feeding through the riser has higher cost, is easy to generate graphite floating, and influences the surface hardness; placing the direct-cooling chiller often causes different graphite forms caused by chilling transition of castings or overheating of the chiller, and the problem of uneven materials occurs, and the color of the position where the chiller is placed and the color of the position where the chiller is not placed are often found to be different after processing.

Disclosure of Invention

Aiming at the problems that the gray iron casting is easy to shrink loose and has uneven hardness in the prior art, the invention provides the method for placing the sand-isolated chilled iron, which realizes the quality requirements of uniform hardness and high hardness of the gray iron casting through simple and feasible operation, meets the quality requirements of the casting, saves the cost and improves the production efficiency.

The technical scheme of the invention comprises the following steps:

determining the pouring direction of the product according to the requirements of processing, process and quality of the product, and according to the material requirement, casting mold strength, wall thickness modulus, pouring temperature, shrinkage porosity property and the like of the product; designing and determining the thickness H of the sand-isolating chilling block and the thickness H of a sand-isolating layer at each position;

the following relations exist among the modulus M of the chilling position of the casting, the thickness H of the sand-isolating cold iron and the thickness H of the sand-isolating layer, wherein H is 3/2M 10, H is a M, and a is 1.1 (the cold iron is HT250 or HT 200);

the sand-isolating chilling block is made of HT200 or HT250 materials, the size is easy to use and convenient to operate, the single weight does not exceed 10kg, and the spacing between the chilling blocks is controlled to be less than 15 mm;

confirming an optimized chilling block scheme through CAE simulation verification;

manufacturing a mold scheme, namely manufacturing the thickness h of a sand separation layer on the mold, namely, the size of a cold iron surface placed on the mold is increased except for the normal casting and process size, and the size h of the sand separation cold iron is required to be increased, and marking the position of the cold iron on the manufactured mold;

before the modeling is started, preparing a chilling block meeting the following standard; performing shot blasting for 15-30 minutes by steel wire shot cutting of 2.0-2.4 mm to ensure that the surface roughness of the chilling block is more than or equal to Ra 25, and ensuring that a using surface is free of corrosion and impurities when in use;

placing a chilling block on the guide rail surface according to the chilling block mark, and filling sand to compact to finish the modeling;

placing the sand mold after the mold opening on an application station, and cleaning floating sand in a cavity;

applying a sand separation layer, and spraying alcohol-based paint by high-pressure spraying, wherein the Baume degree is controlled to be more than 85; the thickness of the 1 st spraying is controlled between 0.2mm and 0.3mm, and then the coating is baked and dried by hot air or natural gas open fire; the thickness of the 2 nd spraying is controlled between 0.3mm and 0.5mm, and then the coating is baked and dried by hot air or natural gas open fire; repeating the operations until the thickness of the sand separation layer reaches the specified thickness, and finishing the manufacturing work of the sand separation layer;

and closing the box, pouring and opening the box to obtain a casting with uniform hardness.

The technical scheme of the invention has the beneficial effects that the chilling block can be firmly and accurately placed at the design position of the chilling block, so that the chilling block can be ensured to fully play a retarding role, the cooling speed of the chilling block position of a casting is improved, the structure and the hardness are improved, the difference of the cooling speed of the chilling block position and the cooling speed of other thin-wall positions is reduced, the integral structure uniformity of the casting is improved, the addition amount of alloy can be reduced or CE is improved, the cost is saved, the castability of a material is improved, and meanwhile, the defects of unnecessary shrinkage porosity, shrinkage cavity and the like in the solidification process of the casting are avoided.

The accurate positioning of the sand separation layer is mainly embodied in three aspects, namely the thickness of the chilling block and the thickness of the sand separation layer are calculated through a formula, and CAE simulation verification optimization is carried out; the thickness of the sand separation layer is directly made on the mold, and the chilling block is directly placed on the surface of the mold, so that the mold is reliable and convenient; the sand separation layer is formed by spraying fine-particle paint, the sand separation layer with the thickness of 0.2-10mm can be realized, the sand separation thickness which cannot be realized by the traditional sand separation layer formed by using resin sand is realized, and the upper layer of the traditional resin sand with the thickness of 0.1-10mm is easy to fall off from a chill, so that sand inclusion of a casting is caused. The coating can be sprayed with different granularities according to the difference of the sand-separating layers, so that the thickness of each layer is increased, and the number of sprayed layers is reduced; the forming of the sand isolating layer can be realized by brush coating or flow coating, but spray coating is preferred, and the spray coating has high spraying pressure, good coating performance and quick drying; firm positioning, rough surface of the chill, fine granularity of the coating, and being beneficial to coating, hanging and bonding the coating and the chill.

According to the sand-isolating chilling block placing method, chilling blocks can be placed in the casting molding or core making process through a simple method, the sand-isolating layer is achieved through spraying, the quality requirements of uniform hardness and high hardness of castings are achieved, the quality requirements of the castings are met, the cost is saved, and the production efficiency is improved.

Drawings

FIG. 1 view of a lathe bed casting

FIG. 2 is a schematic diagram of the relationship between the chill and the mold bevel

FIG. 3 Sand mold diagram

FIG. 4 is a partial enlarged view of a sand mold

Wherein, 1-casting structure; 2-a guide rail; 3-rib plate; 4-molding; 5-isolating sand layer mold; 6-sand-isolation chilling block; 7-sand molding; 8-sand-separating layer

Detailed Description

In order to more clearly illustrate the technical solution of the present invention, the present invention is further described in detail with reference to the following specific examples. Note that the following described embodiments are illustrative only for explaining the present invention, and are not to be construed as limiting the present invention.

The lathe bed casting is made of gray iron, different matrix structures are obtained by changing the cooling speed of the thick-wall position of the guide rail so as to obtain the hardness of the guide rail which is expected to be obtained, the heat dissipation condition of the guide rail position can be improved by placing cold iron, the solidification speed of the guide rail is accelerated, the temperature difference between the thick-wall guide rail position and other thin-wall positions is reduced, and the structure and the hardness are more uniform; the gray iron casting is placed and is directly cooled chill position and not place chill position processing back colour different, and graphite form is different, places and directly cools off the chill and easily leads to graphite to discolour, nevertheless owing to have the thick wall structure, cools off slowly, has the shrinkage porosity after the processing to leak the risk outward, need use sand separation chill control, avoids the problem of discolouing after the processing.

A method for placing sand-isolated chill at the position of a bed guide rail is disclosed, wherein a casting structure 1 is shown in figure 1, a guide rail 2 and a rib plate 3 are arranged on the casting structure 1, the thickness of the chill at each position and the distance from the chill to a casting are designed and determined, the pouring direction of a product is determined according to the requirements of processing, process and quality of the product, the following relations exist among the modulus M of the chilling position of the casting, the thickness H of the sand-isolated chill and the thickness H of a sand-isolated layer, H is 3/2M 10, H is a M, a is 1.1, the sand-isolated chill is HT250, and the casting M is 3; the thickness H of the sand-isolating cold iron is 3/2M 10-45; the thickness h of the sand separation layer is 1.1M 3 3.3;

the single weight of the sand-isolating chilling blocks is not more than 10kg, and the spacing between the chilling blocks is controlled to be less than 15 mm;

manufacturing a mold 4 as shown in fig. 2, manufacturing a sand-separating layer mold 5 by using the thickness h of a sand-separating layer at the position of a guide rail 2, namely, the size of a cold iron surface placed on the guide rail of the mold is removed from the normal casting and process size, the size h of a sand-separating chill needs to be increased, and marking the position of the chill on the manufactured mold by using paint to form the sand-separating layer mold 5 and the sand-separating layer chill 6 on the mold of the guide rail 2;

before the modeling is started, preparing sand-insulated chill meeting the following standard; the steel wire shot is shot-blasted for 15 to 30 minutes by a steel wire shot of 2.0 to 2.4mm, the surface roughness Ra 25 of the chilling block is obtained, and the use surface is free of corrosion and impurities when in use;

placing the sand-isolated chill on the guide rail surface according to the chill mark, and filling sand to compact to finish the molding;

placing the sand mold after the mold opening on an application station, placing the guide rail upwards, and cleaning floating sand in the cavity;

high-pressure spraying of alcohol-based paint is adopted, and the Baume degree is controlled to be more than 85; the thickness of the 1 st spraying is controlled between 0.2mm and 0.3mm, and then the coating is baked and dried by hot air or natural gas open fire; the thickness of the 2 nd spraying is controlled between 0.3mm and 0.5mm, and then the coating is baked and dried by hot air or natural gas open fire; repeating the operations until the thickness of the sand separation layer reaches the specified thickness, and finishing the manufacturing work of the sand separation layer; a sand separation layer 8 is formed between the sand mold 7 and the sand separation chill 6.

Claims

1. A method for placing sand-isolating cold iron, which is characterized in that,

designing and determining the thickness H of the sand-isolating cold iron and the thickness H of the sand-isolating layer at each position;

confirming a sand-isolating cold iron scheme;

increasing the thickness h of a sand-isolating layer on the mold, and marking the position of the sand-isolating chill;

arranging sand-isolating chilling blocks;

placing the sand mold at an application station;

the application of the coating is repeated until the specified sand barrier thickness h is reached.

2. The method for placing the sand-insulated cold iron according to claim 1, wherein the thickness H of the sand-insulated cold iron is 3/2M 10, and the thickness H of the sand-insulated layer is a M.

3. The method for placing the sand-insulated cold iron as claimed in claim 1, wherein the sand-insulated cold iron is made of HT200 or HT250 material.

4. The method of claim 1, wherein the weight of the sand-insulated chill is not more than 10kg, and the chill spacing is controlled to be < 15 mm.

5. The method for placing the sand-insulated cold iron according to claim 1, wherein the sand-insulated cold iron is shot-blasted for 15-30 minutes by a steel wire shot of 2.0-2.4 mm.

6. The method for placing the sand-insulated cold iron as claimed in claim 5, wherein the surface roughness of the sand-insulated cold iron is more than or equal to Ra 25.

7. The method for placing a sand-insulating chilled iron as claimed in claim 1, wherein the coating is an alcohol-based coating, and the Baume degree is 85 or more.

8. The method for placing the sand-insulated cold iron as claimed in claim 1, wherein the coating is sprayed 2 times each time, and the thickness of the 1 st spraying is controlled to be 0.2mm-0.3 mm; the thickness of the 2 nd spraying is controlled to be 0.3mm-0.5 mm.