CN104972066A - Thin-shell sand culturing casting simple technology - Google Patents

Abstract

The invention relates to a precision steel casting industry, and provides a thin-shell sand culturing casting simple technology for precision steel casting. A sodium silicate binder is adopted in shell manufacturing, quartz powder and the small amount of quartz fine sand are used in surface layer powder, a lubricating agent and an antifoaming agent are added to prepare a coating, quartz sand, two layers and a transition layer are scattered, and a coating is prepared through the sodium silicate binder, the quartz powder and mullite powder; mullite sand and a crystallization aluminium chloride solution are scattered to be hardened to prepare a thin shell; a reinforcing layer is not needed, roasting after dewaxing can shorten the heat preservation time, and burning through is easy; defects of shell layering, cracks, air holes, sand clamping, insufficient hardening and the like are overcome. Culturing sand in a dedicated sand box is put, after the sand is jolted through a vibration table, the sand is casted, and an abrasive disc upper cover box is lifted after 15 minutes to 30 minutes, and the culturing sand can fall in a sand collection hopper; sequential solidification cooling is accelerated, and the function of reinforcing the shell in a multilayer manner is achieved; the production period is short, the technology is simple, and the cost is low; compared with an original reinforcing layer shell casting, the cost of a casting of each tonnage is reduced by about 200 yuan; and the technology is suitable for manufacturing pump valve type fine castings of large specifications.

Description

A kind of shell training sand cast Simple process

Technical field

The present invention relates to precision cast steel industry, adopt a kind of shell to train the manufacture process of sand cast Simple process to accurate pump valve foundry goods.Apply the requirement that this technological process can meet the casting of pump valve precise steel casting, both ensured the quality of precise steel casting, and can process for making shell have been simplified again, shorten the production cycle, reduce production cost.

Background technology

Pump valve precise steel casting price is high, possesses high temperature resistant, high pressure, wear-resisting, corrosion-resistant function.Due to complex-shaped, great majority are all foundry goods, and these foundry goods physical dimensions, form and position tolerance, surface finish requirements are high.These foundry goods make shell with waterglass quartz sand usually, less than 25 kilograms smallclothes shells need be coated with two aspect layers repeatedly, one deck transition zone, two ~ tri-layers of settable cementitious forming shell of back-up coat, more than 25 kilograms large part shells need be coated with two aspect layers repeatedly, one deck transition zone, four ~ five layers of settable cementitious forming shell of back-up coat, guarantee casting requirement, and also the production cycle is long, complex process, cost is high.

Summary of the invention

The object of this invention is to provide a kind of shell training sand cast Simple process, with two aspect layers, one deck transition zone, totally three layers of settable cementitious forming shell, be called for short shell, with sodium silicate binder, surface layer powder silica flour adds a small amount of quartzy fine sand, add lubricant, coating made by defoamer, spreads quartz sand; Two layers, transition zone sodium silicate binder, powder quartz sand, mullite are mixed and made into coating, spread mullite sand.Without back-up coat.Adopt and immerse in the crystal aluminum chloride aqueous solution mode of hardening.With the dry process again of water cleaning formwork after the sclerosis of surface layer, transition zone, dry through 960 ~ 1000 DEG C after formwork dewaxing and burn, be incubated the shell made for more than 2 hours.Shell can be irrigated and eliminate layering, crackle, pore, burning into sand, under-ageing defect.Put into special shape mo(u)lding box with this high temperature shell, train into 20/40 order return sand through shake table ram-jolt from sandbox side sand inlet.After casting molten steel 15 ~ 30min, special shape mo(u)lding box upper lid of slinging case, in case, training falls into sand collecting hopper, treat to recycle next time, in shell, the condensation of foundry goods Quick air is solid, clear shell is easy, and foundry goods detects through VT and three-dimensional coordinate can ensure dimensional accuracy, surface quality, can ensure internal soundness through MT, PT, RT Non-Destructive Testing.With short production cycle, technique is simple, and cost is low, has back-up coat shell casting cost per ton to decline more than 200 yuan than originally.And be suitable for manufacturing the larger pump valve class precision castings of specification.

Technical solution of the present invention is a kind of shell training sand cast Simple process, and technological process is characterized in that:

Wax pattern processed---shell processed---dewaxing---roasting---training sand cast---air cooling of unpacking---cleaning shell;

In this technological process, the technical requirement of critical process is:

Wax pattern processed: according to the feature of casting structure, outlet passageway reasonable in design on wax-pattern, high temperature, the effective unimpeded discharge of gases at high pressure in shell when being convenient to pour into a mould;

Shell processed: the first level formulation for coating material, with sodium silicate binder, modulus M=3.2 ~ 3.4, density p=1.32 ~ 1.36g/cm ³powder with 85 ~ 95% 270 order silica flours, the 70/140 order quartz sand compound of 5 ~ 15%, powder liquor ratio n=1.25 ~ 1.40, add the wetting agent of waterglass liquid weight 0.3 ~ 1%, add the defoamer of waterglass liquid weight 0.1 ~ 0.5%, coating after stirring, room temperature 10 ~ 32 DEG C, when relative humidity 35 ~ 80%, is 20 ~ 35S by the viscosity that Ф 6 flow cup is measured, coating layer thickness 0.30 ~ 0.40mm, spreads 40/70 object quartz sand after wax-pattern dip-coating material; Second layer coating materials is filled a prescription, binding agent waterglass, and powder 200 object silica flours, 200 orders do not carry out each 50% compound of powder, powder liquor ratio n=0.80 ~ 1.15, the viscosity stirring rear Ф 6 flow cup measurement is 20 ~ 40S, and coating layer thickness 0.20 ~ 0.30mm, spreads 16/30 order after wax-pattern dip-coating material and do not carry out sand; Transition zone formulation for coating material, binding agent waterglass, the powder 200 order silica flours of about 25 %, 200 orders of about 75% do not carry out powder compound, powder liquor ratio n=1.20 ~ 1.50, the viscosity stirring rear Ф 6 flow cup measurement coating is 40 ~ 80S, spreads 10/20 order and do not carry out sand after wax-pattern dip-coating material; Three layers of sclerosis mode adopt to immerse in the crystal aluminum chloride aqueous solution to harden, and the parameter of hardening bath is: density p _liquid=1.13 ~ 1.28g/cm ³, Baume degrees ⁰b é=16 ~ 28, acidity PH=1.5 ~ 2.5, formwork surface layer, transition zone firm time are greater than 1.5h, and the pond that goes out to harden is put into clear water reserviors and rinsed, dry 5 ~ 24h;

Baking: by the settable cementitious one-tenth shell of two aspect layer one deck transition zones after formwork dewaxing, through 960 ~ 1000 DEG C of roastings, only need be incubated and come out of the stove for more than 2 hours;

Training sand cast: be utilize covering case on face, case chassis to be combined into special shape mo(u)lding box, face, case chassis is put into 20/40 order reuse shell sand, sand layer thickness is greater than 50mm, again high temperature shell is put into cover case, 20/40 order reuse shell sand is put into from cover case side sand inlet, ensure that shell is greater than 80mm to tank wall minimum range, until training is full of shell cup and venthole lower surface, puts down with mechanical vibration generator system ram-jolt, shake and sand flat face and pourable molten steel;

Unpacking air cooling: refer to the rear 15 ~ 30min of cast, smallclothes remove the limit, large part capping, bell-type sandbox of slinging, allows training sand fall into sand collecting hopper, treats to recycle next time, accelerate foundry goods consecutive solidification and cool.

good effect of the present invention is:present invention process is with short production cycle, technique is simple, reduce back-up coat, shorten shell roast temperature retention time, save material, man-hour, the energy, easily irrigate shell again, can eliminate shell layering, crackle, pore, burning into sand, under-ageing phenomenon, cost is low, has back-up coat shell casting cost per ton to decline more than 200 yuan than originally, the steel-casting poured into a mould by this process can ensure inside and outside quality, and the pump valve class foundry goods that suitable for making specification is larger.

Detailed description of the invention

---shell processed---dewaxing---roasting---training sand cast---air cooling of unpacking---cleaning shell is implemented, wax pattern processed by a kind of shell training sand cast simple process.According to the feature of casting structure during wax pattern processed, outlet passageway reasonable in design on wax-pattern, high temperature, the effective unimpeded discharge of gases at high pressure in shell when being convenient to pour into a mould; Shell processed refers to the thin shell making first and second surface layer, the settable cementitious one-tenth of transition zone.The first level formulation for coating material, with sodium silicate binder, modulus M=3.2 ~ 3.4, density p=1.32 ~ 1.36g/cm ³powder with 85 ~ 95% 270 order silica flours, the 80/120 order quartz sand compound of 5 ~ 15%, powder liquor ratio n=1.25 ~ 1.40, add the wetting agent of waterglass liquid weight 0.3 ~ 1%, add the defoamer of waterglass liquid weight 0.1 ~ 0.5%, coating after stirring, room temperature 10 ~ 32 DEG C, when relative humidity 35 ~ 80%, is 20 ~ 35S by the viscosity that Ф 6 flow cup is measured, coating layer thickness 0.30 ~ 0.40mm, spreads 40/70 object quartz sand after wax-pattern dip-coating material, second layer coating materials is filled a prescription, and with sodium silicate binder, powder 200 object silica flours, 200 orders do not carry out each 50% compound of powder, powder liquor ratio n=0.80 ~ 1.15, the viscosity stirring rear Ф 6 flow cup measurement is 20 ~ 40S, and coating layer thickness 0.20 ~ 0.30mm, spreads 20/40 order after wax-pattern dip-coating material and do not carry out sand, transition zone formulation for coating material, with sodium silicate binder, the powder 200 order silica flours of about 25 %, 200 orders of about 75% do not carry out powder compound, powder liquor ratio n=1.20 ~ 1.50, the viscosity stirring rear Ф 6 flow cup measurement coating is 40 ~ 80S, spreads 10/20 order and do not carry out sand after wax-pattern dip-coating material, three layers of sclerosis mode adopt to immerse in the crystal aluminum chloride aqueous solution to harden, and the parameter of hardening bath is: density p _liquid=1.13 ~ 1.28g/cm ³, Baume degrees ⁰b é=16 ~ 28, acidity PH=1.5 ~ 2.5, formwork surface layer, transition zone firm time are greater than 1.5h, and the pond that goes out to harden is put into clear water reserviors and rinsed, dry 5 ~ 24h, dewax in the hot water, daylight shines or air-dry shell, proceeds to heating furnace and carries out shell baking burning, be warmed to 960 ~ 1000 DEG C, only need be incubated and come out of the stove for more than 2 hours, carry out training sand, utilize covering case on face, case chassis to be combined into special shape mo(u)lding box, face, case chassis is put into 20/40 order reuse shell sand, sand layer thickness is greater than 50mm, again high temperature shell is put into cover case, 20/40 order reuse shell sand is put into from cover case side sand inlet, ensure that shell is greater than 80mm to tank wall minimum range, until training is full of shell cup and venthole lower surface, use mechanical vibration generator system ram-jolt, shake is flat sands flat face and pourable molten steel, 15-30min unpacks air cooling after being cast, smallclothes remove the limit, large part capping, to sling sandbox, training sand is allowed to fall into sand collecting hopper, treat to recycle next time, accelerate the cooling of foundry goods consecutive solidification, casting head of casting portion faces shell is clashed into shake shell machine, crushing and clearing shell is easy.

Claims (3)

1. a shell training sand cast Simple process, technological process is characterized in that: wax pattern processed, and---------roasting---trains sand to pour into a mould---air cooling of unpacking---cleaning shell to shell processed in dewaxing.

2. a kind of shell training sand cast Simple process as claimed in claim 1, it is characterized in that described step is for the cast of training sand: be utilize covering case on face, case chassis to be combined into special shape mo(u)lding box, face, case chassis is put into 20/40 order reuse shell sand, sand layer thickness is greater than 50mm, again high temperature shell is put into cover case, 20/40 order reuse shell sand is put into from cover case side sand inlet, ensure that shell is greater than 80mm to tank wall minimum range, until training is full of shell cup and venthole lower surface, puts down with mechanical vibration generator system ram-jolt, shake and sand flat face and pourable molten steel.

3. a kind of shell training sand cast Simple process as claimed in claim 1, it is characterized in that described step is for air cooling of unpacking: refer to the rear 15 ~ 30min of cast, smallclothes remove the limit, large part capping, to sling cover case, allow training sand fall into sand collecting hopper, treat to recycle next time, accelerate the cooling of foundry goods consecutive solidification.