CN103894548A

CN103894548A - Lost foam casting process for flywheel cover of heavy truck engine

Info

Publication number: CN103894548A
Application number: CN201410140622.4A
Authority: CN
Inventors: 曹小康
Original assignee: HANZHONG YANHANG PRECISION MACHINERY MANUFACTURING Co Ltd
Current assignee: HANZHONG YANHANG PRECISION MACHINERY MANUFACTURING Co Ltd
Priority date: 2014-04-01
Filing date: 2014-04-01
Publication date: 2014-07-02

Abstract

The invention relates to a lost foam casting process for a flywheel cover of a heavy truck engine. The lost foam casting process comprises the following steps of manufacturing a model of which the shape and the size are consistent with those of a casting from expanded plastics prepared by mixing expandable polystyrene and polymethyl methacrylate, coating the model with a refractory and air-permeable material, drying, hardening the model, placing the model in a sand box, filling dry sand, performing vibration ramming, pouring metal liquid, and performing vacuumizing to form negative pressure in the pouring process to realize the replacement of the foam model by the metal liquid and enable the foam model to disappear without traces. According to the process, various problems of a plurality of defects in the casting, surface roughness, high raw material consumption, severe environmental pollution and the like in a conventional sand mold casting process for the flywheel cover of the heavy truck engine are solved, and the lost foam has the advantages of high inner quality, surface brightness and cleanliness, high production efficiency, slight environmental pollution and the like.

Description

Heavily block flywheel shell of engine lost foam casting process

Technical field

The invention belongs to and heavily block engine manufacture field, particularly one is heavily blocked flywheel shell of engine lost foam casting process.

Background technology

At present, what heavily block the extensive employing of flywheel shell of engine casting is traditional sand casting process, basic craft course is: first with timber or steel material finished parts model, recycle this model, carry out moulding with the molding sand that added binding agent, then by model by taking out in sand mold, thereby produce foundry goods space die cavity, afterwards die cavity is dried to sclerosis, finally in the die cavity of foundry goods space, pour into metal liquid, the production process of cooling rear acquisition metal casting product.Although its model can be reused, the process of taking out in by sand mold at model can cause sand mold precision to reduce, and surface quality declines, because its molding sand uses binding agent, moulding cost is higher simultaneously.

This kind of traditional sand mould casting method, technique falls behind, technological equipment drops into many, and occupied ground is large, raw materials consumption is many, allowance is large, machined workload is large, production efficiency is low, and labour intensity is large, production cost is high, environmental pollution is also very serious, and the dimensional discrepancy of casting finished products is large, surface roughness is poor, simultaneously, also easily there is the defects such as pore, shrinkage porosite, burning into sand, crackle, segregation in foundry goods, casting qualified rate is low, yield rate is low.

In order to overcome the above-mentioned defect of current sand casting bell housing, improve casting qualified rate, reduce production costs, must innovation foundry engieering, change traditional bell housing sand mould casting method, with reach savings, efficiently, the object of environmental protection.

Lost foam casting process results from the U.S. in last century five, the sixties, is mainly used at that time the casting of aluminum alloy complex parts.Technology of EPC has the advantages such as internal flaw is few, any surface finish, production efficiency is high, labour intensity is low, environmental protection.

Literature search: a kind of evaporative pattern (number of patent application: 201020206268) summary: a kind of evaporative pattern of engine flywheel housing casting use of engine flywheel housing casting use, for alms bowl build, comprise upper and lower two parts, the criss-cross upper running channel that comprises upper shell and level is divided on top, the down sprue of the Y-shaped that comprises lower house and level is divided in bottom, there is sprue at the center of upper and lower two running channels, sprue is positioned on the axis of housing, on the contact-making surface of upper-lower casing, have locating hole, upper-lower casing bonds together by contact-making surface.This running gate system has following advantage: by three lower ingates, sprue, upper four ingates and foundry goods flywheel shell organically combine, form a birdcage structure, effectively control the distortion of baseplane and upper flange face in molten steel solidification process, make flywheel shell casting quality produce transition, first, yield rate brings up to 95% by original 80%.The second, ovality is reduced to 1.2mm by original 5mm, and the unevenness of baseplane drops to 1.1mm by original 3.5mm, and the 3rd, upper flange position black field trash eliminates substantially.

Summary of the invention

In order to overcome prior art deficiency, the object of this invention is to provide a kind of new casting method of heavily blocking flywheel shell of engine based on evaporative pattern technology.

Realizing the technical scheme that the object of the invention adopts is: lost foam casting process is the foamed plastic that utilizes expandable polystyrene to mix with polymethyl methacrylate, make and foundry goods shape, the model of consistent size, hang and be coated with fire-resistant and ventilative material and dry after sclerosis, model is inserted in sandbox, insert dry sand, carry out vibration ramming, casting metal liquid again, in casting process, vacuumize formation negative pressure, realize the displacement of metal liquid to bubbles model, and the disappearance that bubbles model is left no trace, thereby copy the foundry goods the same with foamed polystyrene pattern, its concrete grammar is as follows,

1. design, manufacture coarse pitch soft drive lost foam production line,

2. bell housing is cut into some splicing blocks, and manufactures each splicing block foaming molding mold,

3. expandable polystyrene plastics prefoam,

4. make the each splicing block foamed plastic of bell housing model, and dry, comprise dead head, ingate etc.,

5. with the corresponding position of the each splicing block mould assembly of adhesive bond face, and combine ingate, dead head, form and comprise the evaporative pattern model that dead head, ingate and cast model are integrated,

6. on evaporative pattern model, hang and be coated with fire-resistant, ventilative coating, dry 30 ℃～60 ℃ bakings,

7. model packs sandbox into, inserts dry sand,

8. plain bumper on sandbox, jolt ramming sand mold,

9. vacuumize, form negative pressure, casting metal liquid, makes foamed plastic be gasificated into gas and extracts out, and metal liquid displacement foamed plastic model, forms bell housing foundry goods,

10., after cooling, perforated molding sand, takes out bell housing foundry goods,

11. cleaning foundry goods.

Good effect of the present invention is that lost foam casting process is applied to and heavily blocks bell housing casting, change traditional sand casting process, Product Precision and surface roughness are improved, reduce internal flaw, meanwhile, reduce product and dropped into and consume, reduced production cost, improve labor productivity, reduced environmental pollution.Lost foam casting is compared with traditional sand casting, and concrete advantage is as follows:

1. technological process is short, and labor productivity is high;

2. dimensional accuracy is high, high conformity;

3. the internal flaw such as pore, shrinkage porosite obviously reduces;

4. surface quality is high, bright and clean without burr;

5. need that machining position is few, allowance is little, machined workload obviously reduces;

6. labour intensity is low;

7. environmental pollution is little.

Accompanying drawing explanation

Fig. 1 is the front view of heavy card flywheel shell of engine evaporative pattern of the present invention,

Fig. 2 is the top view of Fig. 1 of the present invention,

Fig. 3 is the top view of Fig. 1 of the present invention.

The specific embodiment

A heavily card flywheel shell of engine casting method based on evaporative pattern technology, it comprises the following steps and process:

1.. design, manufacture coarse pitch soft drive lost foam production line, mainly comprise: coarse pitch soft drive automatic assembly line; Raise the dry sand treatment system of sand cooling bed as nucleus equipment to roll; By the moulding district that has the three-dimensional vibrating-compaction table of tiltable function and the chevron shaped sand storage bin of human oriented design concurrently and form; From letting out sand angle chamber vacuum sandbox etc.Coarse pitch soft drive lost foam production line is produced by the design of solid anginin Casting Equipment Co., Ltd.

2.. bell housing is cut into some splicing blocks, and the quantity of the splicing block after cutting and direction, consider the factor that is conducive to cast and is conducive to splice this two aspect.Then manufacture respectively each splicing block foaming molding mold according to the structure of splicing block.

3.. expandable polystyrene plastics are carried out to prefoam.

4.. with each splicing block foaming molding mold, the each splicing block foamed plastic of compacting bell housing model, and dry, comprise dead head, ingate etc.

5.. with the corresponding position of the each splicing block mould assembly of adhesive bond face, and combine ingate, dead head, form and comprise the evaporative pattern model that dead head, ingate and cast model are integrated.

6.. on evaporative pattern model, hang and be coated with fire-resistant, ventilative coating, dry 30 ℃～60 ℃ bakings.

7.. model packs sandbox into, inserts dry sand.

8.. plain bumper on sandbox, jolt ramming sand mold.

9.. connect vavuum pump at sandbox bleeding point and vacuumize, make formation negative pressure in sandbox.

10.. casting metal liquid, make foamed plastic be melted into gas and extract out, molten metal displacement foamed plastic model, forms bell housing foundry goods.

After cooling, perforated molding sand, takes out bell housing foundry goods.

Cleaning foundry goods.

Claims

1. heavily block a flywheel shell of engine lost foam casting process, it is characterized in that, concrete technical scheme is as follows:

1.. design, manufacture coarse pitch soft drive lost foam production line,

2.. bell housing is cut into some splicing blocks, and manufacture each splicing block foaming molding mold,

3.. the prefoam of expandable polystyrene plastics,

4.. make the each splicing block foamed plastic of bell housing model, and dry, comprise dead head, ingate etc.,

5.. with the corresponding position of the each splicing block mould assembly of adhesive bond face, and combine ingate, dead head, form and comprise the evaporative pattern model that dead head, ingate and cast model are integrated,

6.. on evaporative pattern model, hang and be coated with fire-resistant, ventilative coating, dry 30 ℃～60 ℃ bakings,

7.. model packs sandbox into, inserts dry sand,

8.. three-dimensional vibrating-compaction table on sandbox, jolt ramming sand mold,

9.. vacuumize, form negative pressure, casting metal liquid, makes foamed plastic be melted into gas and extracts out, and molten metal displacement foamed plastic, forms bell housing foundry goods,

10.. after cooling, perforated molding sand, takes out bell housing foundry goods, cleaning foundry goods.

2. heavy card flywheel shell of engine lost foam casting process according to claim 1, it is characterized in that: described step 1. middle soft drive is, refer to that roller independently rotates, drive sandbox to move ahead, sandbox delivery area, moulding district, pouring area, each district, heat preservation zone are relatively independent.

3. heavy card flywheel shell of engine lost foam casting process according to claim 1 and 2, is characterized in that: described step 10. in, what the method for molding sand knockout adopted is the mode of leaking sand in the end.