CN104550848A

CN104550848A - V-method vacuum casting technology

Info

Publication number: CN104550848A
Application number: CN201310505765.6A
Authority: CN
Inventors: 常云青
Original assignee: QINGDAO HEDELONG MACHINERY CO Ltd
Current assignee: QINGDAO HEDELONG MACHINERY CO Ltd
Priority date: 2013-10-24
Filing date: 2013-10-24
Publication date: 2015-04-29

Abstract

The invention discloses a V-method vacuum casting technology. The V-method vacuum casting technology comprises the following steps of manufacturing a pattern with an exhaust chamber and exhaust holes; (2) covering the pattern by using a plastic thin film which is in a plastic state after being baked, sucking air between the pattern and the plastic thin film by using a vacuum pump so that the thin film adhered to the surface of the pattern is molded, and spraying the thin film by using fast-dry coatings; (3) placing a sand box with a filtering exhaust tube on a mold plate with the plastic thin film; (4) filling dry sand without any binders or additives in the sand box, compacting and flattening the sand in the box, placing a sealing film on the sand, opening an exhaust valve and sucking air in the sand so that pressure difference exists between the inside and the outside of a casting mold; (5) stopping the vacuum state of the inside of the pattern, performing stripping, continuing to vacuumize the casting mold until core setting is performed, and performing mold assembling and casting; and (6) solidifying metal liquid after casting, and stopping exhausting air form the casting mold so that the casting mold can collapse in disorder when the pressure in the casting mold is close to atmospheric pressure. The casting mold has high hardness due to the effect of pressure difference, and the hardness of the sand can reach 85-95. The V-method vacuum casting technology has the advantages that the quality of castings is improved, equipment is simplified, the investment is saved, the service lives of the mold and the sand box are long, the metal availability is high, and a work environment is improved.

Description

V method vacuum casting process

Technical field

The invention belongs to alloy cast iron casting technology field, be specifically related to a kind of V method vacuum casting process.

Background technology

V method casting (vacuum sealed molding) is that first early seventies is invented by Japan.Japan afterwards, the U.S., European Countries casting expert, through extensively research, establish the best of V method moulding and most basic skills.Current this novel casting method has been widely used in cast iron, cast steel, non-ferrous casting industry.The weight of foundry goods is from several two to weighing tens tons.According to nineteen ninety-five statistics, the whole world uses about family more than 300 of V method moulding producer.Wherein 180, Japan; 10, the U.S., 85, Europe.Along with the manufacturing center in the world shifts to China, American-European and Japanese V method foundry enterprise reduces; And Chinese V method casting landscape is solely good; National V method foundry enterprise is added up more than more than 200 families according to 2010; Wherein more than ten bars are Introduced from Japan and German vacuum sealed molded line equipment and technology.V method casting any surface finish, dimensional accuracy is high, and technological operation is easy, and production cost is low, applied widely, and investment cost is few.Significant competitive advantage is had in quality, technology and economic benefit.Some measures and methods of quality control and technical controlling.

Summary of the invention

In order to overcome the problems referred to above that prior art field exists, the object of the invention is to, a kind of V method new Process of Vacuum Casting is provided.

V method new Process of Vacuum Casting provided by the invention, this method is a preparation V method vacuum casting process of development in recent years, is also attributable to casting by its principle.

1) manufacture with exhaust chamber and aspirating hole apperance.

2) have the covered rearing with plastic film of mecystasis in apperance by through baking, when overlay film taken out by vavuum pump with air, make film be attached to apperance on the surface shaping (being called that overlay film is shaped), spray quick drying paint.

3) by the sandbox with filtering suction pipe, be placed on and covered in the template of plastic sheeting.

4) to filling in sandbox without any binding agent and accrete dry sand.Molding sand in compacting box, strike off, put sealing film, open evacuating valve, pump the air in molding sand, make to there is pressure differential inside and outside casting mold, due to the effect of pressure differential, make casting mold have higher hardness, core hardness tester reading can reach 85 ~ 95.

5) remove the vacuum in apperance, then carry out molding.Casting mold will continue to vacuumize, until lower core, and mould assembling, cast.

6) treat that molten metal solidifies after cast, stop bleeding to casting mold, in type during pressures near atmospheric, casting mold is just defeated and dispersed voluntarily.

V method new Process of Vacuum Casting provided by the invention, its beneficial effect is:

1) improve casting quality, cast(ing) surface is bright and clean, clear-cut, size are accurate, mould hardness is even, and skinning is easy.

2) simplified apparatus, investment reduction, reduces and runs and maintenance cost, economizes no-bonder, additives and sand blender.Reclamation of return sand rate is up to 95%, and equipment investment reduces 30% ~ 60%, and labour reduces about 35%.

3) mould and sandbox long service life.

4) using rate of metal is high.The moulding of V method, metal fluidity is good, and stowage capacity is strong.Mould hardness is high, and cooling is slow, and the size reducing rising head improves product yield.

5) improve working environment, reduce the labour intensity of workman.

6) molding operation is more complicated, to vacuumizing eventually from moulding,

7) because of the percentage elongation of plastic sheeting and the restriction of mouldability, external form V method, core resin sand core just can make intricate casting, have impact on this technique and expands application.

8) be applicable to Single unit job lot production and be also applicable to mechanical automation production in enormous quantities simultaneously; The foundry goods such as cast iron, cast steel, nonferrous alloy can be produced.

Detailed description of the invention

Below in conjunction with embodiment, to V method vacuum casting process provided by the invention, be described in detail.

Embodiment one

Casting technique is as follows:

1) manufacture with exhaust chamber and aspirating hole apperance.

V method is cast apperance used and occupy very important status in V method Foundry Production, and the quality of its quality directly affects the quality of foundry goods.Current V method casts apperance used generally with wooden.The feature of V method casting self, requires that any surface finish of apperance own, dimensional accuracy are high; V method mold and pattern for casting sample, due to the impact by feature own, its technique shrinkage factor and gradient are less than the Castingother techniques such as clay-bonded sand, water-glass sand, resin sand: even some foundry goods can not need to discharge film gradient.Root pick unlike material and structure both shrinks rate are between 0.2% ~ 0.8%, and gradient is between 0 ~ l0 °.V method moulding template, both side ends is provided with the guide coordinating with sandbox and locate, below template, be provided with aspirating chamber, the knot of template

Structure adopts wooden assembling.In the moulding of V method apperance do not contact (across thin film and coating) with sand mold thus apperance wearing and tearing and distortion very little, long service life, but the particular/special requirement that V method will be considered on mold-like structure.

1. apperance is made hollow, makes it to form aspirating chamber, and larger apperance inside arranges reinforcement, and to ensure under suction function of bleeding, apperance is broken or be out of shape.

2. apperance avoids sharp-pointed corner angle as far as possible, in order to avoid overlay film is inhaled not in place or inhaled broken overlay film.

3. apperance gradient can suitably reduce, this is because more smooth between film and apperance during the moulding of V method, frictional force is very little, and required withdrawing pattern power is less.

4. apperance surface needs to offer aspirating hole, and aspirating hole diameter is generally 0.5-2.5mm, the most handy vent plug, diameter 8 ~ l0mm.

5. wooden model surface should not brushing coating agent which has to be dissolved in alcohol before use solution, also should not brushing heatproof lower than other paint of 60 ~ 70 DEG C, otherwise there will be mucosa events after being covered with by the plastic sheeting warmed, affect withdrawing pattern.The casting of V method can reduce the usage quantity of core and directly improve the quality on the surface of foundry goods.Will take into full account the mould strength that V method is cast lower, shock-resistant poor feature during technology establishment, in the making of apperance, the making of apperance should be fully realized V method and cast the feature vacuumized and the needs ensureing to inhale film mouldability; It is shaping that local strengthening vacuumizes suction film, and the cavity position being difficult to inhale film shaping for some can take strengthening to vacuumize measure on mold-like structure, is covered like this by the speed of bleeding regulating with the suction reaching regional area facial mask.Internal structure is noted at massive plate and die joint place, ensure enough intensity and aeration smoothly.Apperance ensures correct location when making, except utilizing alignment pin, and can also with location such as close-overs.Plastic sheeting and the shaping V method casting of overlay film are with plastic sheeting by heating after-tack, and utilize vacuum that it is adsorbed on rough apperance on the surface, because apperance profile is complicated; Require that plastic sheeting has good manufacturability.Do not produce folding line and break; V method casting plastic sheeting very book, general at 0.03 ~ 0.25mm, require that plastic film has sizable extensibility, the quality of the forming ability of plastic film in apperance or core box, direct surface smoothness and the dimensional accuracy affecting foundry goods, therefore the selection of plastic film and the control of quality and using method are the important key links of V method casting.Plastic film is selected to require as follows:

1. plastic film must not have bubble to drip and the defects such as pin hole.

2. when shaping, shape defect should not develop.

3. the book film after shaping can not retain elasticity again.

4. book film does not allow to cling with model material.

Claims

1. a V method new Process of Vacuum Casting, is characterized in that: 1) manufacture with exhaust chamber and aspirating hole apperance; 2) have the covered rearing with plastic film of mecystasis in apperance by through baking, when overlay film taken out by vavuum pump with air, make film be attached to apperance shaping on the surface, spray quick drying paint; 3) by the sandbox with filtering suction pipe, be placed on and covered in the template of plastic sheeting; 4) to filling in sandbox without any binding agent and accrete dry sand, molding sand in compacting box, strike off, put sealing film, open evacuating valve, pump the air in molding sand, make to there is pressure differential inside and outside casting mold, due to the effect of pressure differential, make casting mold have higher hardness, core hardness tester reading can reach 85 ~ 95; 5) remove the vacuum in apperance, then carry out molding, casting mold will continue to vacuumize, until lower core, and mould assembling, cast; 6) treat that molten metal solidifies after cast, stop bleeding to casting mold.