CN103357819A - Bucket tooth investment casting method - Google Patents

Abstract

The invention relates to a bucket tooth investment casting method. According to the invention, ceramic wear-resistant particles replace a refractory material, the ceramic wear-resistant particles and a binder are used to prepare a liquid paint which is coated on the surface of a mould so as to prepare a section mould, an investment pattern is melded, an alloy liquid is injected, the investment pattern is solidified with the cooling of the injected alloy liquid so as to form a casting, the ceramic wear-resistant particles are introduced onto the surface of the casting and heat treatment is carried out so as to increase a ceramic hardened layer on the surface of the casting. Thus, surface hardness of the casting is raised. By the adoption of the casting method, the casting is formed at a time, the surface is smooth and bright, the size is accurate, the purpose of less cutting or no cutting can be achieved, and the hardness is greatly raised due to the ceramic hardened layer on the surface. Therefore, the method provided by the invention is especially suitable for alloy castings such as bucket tooth and the like which require high surface hardness.

Description

A kind of investment casting method of bucket tooth

Technical field

The present invention relates to a kind of casting method, specifically, relate to a kind of investment casting method of bucket tooth.

Background technology

Bucket tooth generally is to adopt special-purpose high-strength cast steel, is processed as first the tooth base, carries out the technical process such as machining, tooth Profile Machining, heat treatment, fine finishining again and makes, and process cycle is long, and processing technology is complicated, and the machined difficulty is large.And the bucket tooth case hardness that requirement makes is high, and wearability is good.

Casting is one of main method of manufactured parts blank, preparation method quite efficiently, especially for the part of some brittle metal or alloy material, the processing method that foundry engieering is commonly used especially, its forming principle is: with the METAL HEATING PROCESS fusing, make it have flowability, then be poured in the casting mold die cavity with definite shape, under the effect of gravity or external force, be full of die cavity, cool off and be frozen into foundry goods or part.

Traditional casting technique generally comprises following steps: a, make the apperance that molding and core making is used according to the shape of product; B, apperance is put into sandbox, carry out mould assembling after back-up sand, consolidation, the molding; C, the liquid metal after will melting are poured in the die cavity in the sandbox; D, peeling foundry goods.

At present, traditional casting technique all needs a large amount of manpowers when the preparation of molding sand, in the manufacturing process of sand mold and in the peeling foundry goods in later stage, labour intensity is larger, has wasted the human resources of a large amount of preciousnesses, casting simultaneously each product needs to repeat above-mentioned operation, and production efficiency is low.

Based on defects, the present invention is directed to the characteristics of bucket tooth, a kind of improved gear investment casting method is provided.

Summary of the invention

The purpose of this invention is to provide a kind of investment casting method that can be used for bucket tooth.

Casting method of the present invention is improved investment casting method, and model casting claims again " lost-wax casting ".This method is that easy fusible pattern material is injected die mould (mould), makes fusible pattern, and it is assembled into module, then is coated with the liquid coating that application refractory material and binding agent are made on the module surface, spreads fire-resistant sand grains at coating again, makes it subsequently to harden into shell.So repeated multiple times, just form the multilayer shell.With shell heating, the fusible pattern fusing is flowed out, housing toward wherein pouring into liquid alloy, solidifies by operations such as cleanings and namely obtains foundry goods after roasting.

Based on the requirement to bucket tooth, be that case hardness is high, wearability is good, the present invention with the ceramic wear-resisting particle as refractory material, the liquid coating that is made into binding agent is coated in the module surface, make pattern, inject alloy liquid, along with the cooled and solidified formation foundry goods of the alloy liquid that injects, the ceramic wear-resisting particle is introduced cast(ing) surface, then heat treatment makes cast(ing) surface increase one deck pottery hardened layer, improves the case hardness of foundry goods.

Specifically, invent described casting method, may further comprise the steps:

1) preformed fusible model is immersed in the slurry of ceramic particle and colloid liquid-containing binder formation, form coating at described model, drying;

2) slurry that sprayable refractory particle or applying of refractory material particle and colloid liquid-containing binder consist of on the described coating of step 1), drying;

3) molten fusible pattern, the Baking of losing;

4) alloyage material, alloy material melting, cast;

5) cleaning: comprise shelling, remove the processing steps such as dead head, cleaning, check, soldering;

6) heat treating castings.

Wherein, step 1) and/or step 2) can repeat, until obtain suitable thickness;

Described ceramic particle can be carborundum, silicon nitride or tungsten carbide, and the size of particle can be selected this area granular size commonly used, preferred 20-500 μ m; More preferably 20-100 μ m;

Adopt model casting, the foundry goods once-forming, any surface finish, size are accurate, can reach few cutting or without the purpose of cutting, and the surface has ceramic hardened layer, and hardness improves greatly, is particularly suitable for preparing the alloy-steel casting that bucket tooth etc. needs high surfaces hardness.

The specific embodiment

The present invention is described further below in conjunction with specific embodiment.Specialize such as nothing, the used raw material of the present invention is commercial.

Embodiment 1

According to following steps, the cast gear sample:

1) preformed fusible model is immersed in the slurry of ceramic particle and colloid liquid-containing binder formation, form coating at described model whereby, spray-drying; Described ceramic particle can be carborundum, silicon nitride or tungsten carbide, and the size of particle is 20-50 μ m; Described colloid liquid-containing binder is polyacrylamide; The weight ratio of ceramic particle and colloid liquid-containing binder is 1:0.1 in the slurry that ceramic particle and colloid liquid-containing binder consist of;

Wherein, step 1) repeats 3 times;

2) slurry that applying of refractory material particle and colloid liquid-containing binder consist of on the described coating of step 1), spray-drying; Wherein, described refractory material is silica; The weight ratio that described fire resisting material particle and gelling form material is 100:5;

Wherein, step 2) repeat 2 times;

3) 1 hour molten fusible pattern, Baking of losing of 200 ℃ of insulations;

4) alloyage material, chemical composition sees Table 1, and alloy material utilizes vacuum induction melting, fusion temperature: 1580 ℃, pouring temperature is 1530 ℃;

Table 1 chemical component table

5) cleaning: comprise shelling, remove the processing steps such as dead head, cleaning, check, soldering;

6) heat treating castings: 860 ℃ of insulations oil quenching after 1 hour, 500 ℃ of insulations were cooled off with stove after 1 hour.

Embodiment 2

According to following steps, casting bucket tooth sample:

1) preformed fusible model is immersed in the slurry of ceramic particle and colloid liquid-containing binder formation, form coating at described model whereby, spray-drying; Described ceramic particle is the mixture of silicon nitride and tungsten carbide (weight ratio 10:1), and the size of particle is 100-200 μ m; Described colloid liquid-containing binder is polyacrylate; The weight ratio of ceramic particle and colloid liquid-containing binder is 1:10 in the slurry that ceramic particle and colloid liquid-containing binder consist of;

Wherein, step 1) repeats 5 times;

2) slurry that applying of refractory material particle and colloid liquid-containing binder consist of on the described coating of step 1), spray-drying; Wherein, described refractory material is magnesia; The weight ratio that described fire resisting material particle and gelling form material is 100:10;

Wherein, step 2) repeat 3 times;

3) 1 hour molten fusible pattern, Baking of losing of 400 ℃ of insulations;

4) alloyage material, chemical composition sees Table 1, and alloy material utilizes vacuum induction melting, fusion temperature: 1620 ℃, pouring temperature is 1560 ℃;

5) cleaning: comprise shelling, remove the processing steps such as dead head, cleaning, check, soldering;

6) heat treating castings.The heat treatment of step 6) medium casting can followingly be carried out: 900 ℃ of insulations oil quenching after 3 hours, 600 ℃ of insulations were cooled off with stove after 3 hours.

Embodiment 3

According to following steps, casting bucket tooth sample:

1) preformed fusible model is immersed in the slurry of ceramic particle and colloid liquid-containing binder formation, form coating at described model whereby, spray-drying; Described ceramic particle is tungsten carbide, and the size of particle is 50-100 μ m; Described colloid liquid-containing binder is the mixture of polyacrylamide and polyacrylate; The weight ratio of ceramic particle and colloid liquid-containing binder is 1:0.5 in the slurry that ceramic particle and colloid liquid-containing binder consist of;

Wherein, step 1) repeats 3 times;

2) slurry that applying of refractory material particle and colloid liquid-containing binder consist of on the described coating of step 1), spray-drying; Wherein, described refractory material is aluminium oxide; The weight ratio that described fire resisting material particle and gelling form material is 100:1;

Wherein, step 2) repeat 2 times;

3) 2 hours molten fusible pattern, Bakings of losing of 300 ℃ of insulations;

4) alloyage material, chemical composition sees Table 1, and alloy material utilizes vacuum induction melting, fusion temperature: 1600 ℃, pouring temperature is 1550 ℃;

5) cleaning: comprise shelling, remove the processing steps such as dead head, cleaning, check, soldering;

6) heat treating castings: 880 ℃ of insulations oil quenching after 2 hours, 550 ℃ of insulations were cooled off with stove after 1 hour.

Embodiment 4

According to following steps, casting bucket tooth sample:

1) preformed fusible model is immersed in the slurry of ceramic particle and colloid liquid-containing binder formation, form coating at described model whereby, spray-drying; Described ceramic particle is carborundum, and the size of particle is 40-80 μ m; Described colloid liquid-containing binder is polyacrylamide; The weight ratio of ceramic particle and colloid liquid-containing binder is 1:0.3 in the slurry that ceramic particle and colloid liquid-containing binder consist of;

Wherein, step 1) repeats 3 times;

2) sprayable refractory particle on the described coating of step 1); Wherein, described refractory material is the mixture of silica and aluminium oxide;

3) 2 hours molten fusible pattern, Bakings of losing of 280 ℃ of insulations;

4) alloyage material, chemical composition sees Table 1, and alloy material utilizes vacuum induction melting, fusion temperature: 1620 ℃, pouring temperature is 1530 ℃;

5) cleaning: comprise shelling, remove the processing steps such as dead head, cleaning, check, soldering;

6) heat treating castings: 900 ℃ of insulations oil quenching after 1 hour, 500 ℃ of insulations were cooled off with stove after 1.5 hours.

Bucket tooth to embodiment 1-4 preparation is taken a sample along diametric(al), and sample carries out the torsional fatigue strength test, and employings torque capacity is that (=500kgf.m) reverse torsion machine, alternation ground change stress condition and carrying out is reaching 1 * 10 for 4900Nm⁵Stress during inferior life-span is tried to achieve as fatigue strength.

In addition, to the sample made from the same terms, adopt thickness and the hardness of light microscope determining hardened layer.The results are shown in Table 2:

The test result of table 2 sample

The present invention adopts investment casting method, the foundry goods once-forming, and any surface finish, size are accurate, can reach few cutting or without the cutting purpose, and the surface has ceramic hardened layer, and hardness improves greatly, is particularly suitable for preparing the alloy-steel casting that bucket tooth etc. needs high surfaces hardness.

Claims (2)

1. the investment casting method of a bucket tooth is characterized in that, may further comprise the steps:

1) preformed fusible model is immersed in the slurry of ceramic particle and colloid liquid-containing binder formation, form coating at described model whereby, drying;

2) slurry that sprayable refractory particle or applying of refractory material particle and colloid liquid-containing binder consist of on the described coating of step 1), drying;

3) molten fusible pattern, the Baking of losing;

4) alloyage material, alloy material melting, cast;

5) cleaning: comprise shelling, remove the processing steps such as dead head, cleaning, check, soldering;

6) heat treating castings;

In the step 1), described ceramic particle is carborundum, silicon nitride or tungsten carbide.

2. the investment casting method of bucket tooth according to claim 1 is characterized in that, the size of described ceramic particle is 20-500 μ m; Preferred 20-100 μ m.