CN102009129A

CN102009129A - Process for casting lost foam composite ceramic mould shell

Info

Publication number: CN102009129A
Application number: CN2009101690234A
Authority: CN
Inventors: 杜孔明; 卢定全; 陈辉
Original assignee: DONGFENG INVESTMENT CASTING Co Ltd
Current assignee: DONGFENG INVESTMENT CASTING Co Ltd
Priority date: 2009-09-07
Filing date: 2009-09-07
Publication date: 2011-04-13

Abstract

The invention relates to a process for casting a lost foam composite ceramic mould shell, which is mainly characterized by comprising the following steps of: forming a composite shell by coating a silica sol mould shell and a water glass shell on a lost foam expandable polystyrene (EPS) mould, preroasting the composite shell at a lower temperature, and roasting at a high temperature to obtain a composite ceramic cavity; and carrying out the relevant treatments of cooling, disassembly, cleaning and the like after casting a metal solution to obtain a casting.

Description

Disappearance mould composite ceramics shell casting technique

Affiliated technical field

The invention belongs to a kind of hot investment casting moulding process, be used for the moulding preparation of the higher metal parts of surface quality and dimension precision requirement.

Background technology

A kind of new casting method in conjunction with lost foam casting technology and melted module precise casting technology characteristics has been proposed in the patent 200810007693.1 " a kind of precision casting technique of ceramic shell lost foam ", this patent applies the known precision-investment casting silicasol case of several layers with the disappearance mould formpiston outside of part, remove the mould that disappears in the ceramic case through preroast, 1000 ℃ of roastings, ceramic shell landfill sandbox with hollow, around shell, pour into a mould molten steel under the subnormal ambient, obtain foundry goods.

Be used to produce the precision casting of general requirement, the deficiency of this technology is that the cost of silicasol case own is higher, and known relatively in the industry sodium silicate shell, and sintering temperature also exceeds about 200 ℃, and comprehensive manufacturing cost is higher.

Summary of the invention

In order to reduce the manufacturing cost of method described in the patent 200810007693.1, invention " disappearance mould composite ceramics shell casting technique ", apply the composite shell of silicasol case and sodium silicate shell in disappearance mould formpiston outside, control and reduce the number of plies of shell coating simultaneously, separate temperature and the requirement of composite shell sintering temperature according to EPS disappearance mold crack, reduce formwork roasting (containing burning disappearance mould) temperature.

Technical scheme of the present invention is:

1, the shell of disappearance mould (EPS mould) coating constitutes: ground floor is a silicasol case, promptly is binding agent with the Ludox, is refractory powder preparation coating with schmigel, zirconium English powder or mullite powder etc., and sanding material is and the isonomic fire-resistant sand grains of powder; The second layer is a sodium silicate shell, is binding agent with waterglass promptly, is preparation of powder coating with high alumina composite powder or other refractory materials etc., and sanding material can be selected mullite sand or natural siliceous sand etc. for use.

2, applying the number of plies is 3～5 layers, specifically decides on part dimension; Except that ground floor was silicasol case, all the other were sodium silicate shell;

3, module preroast (setting a little more than the liquefaction of EPS mould) temperature is 165～200 ℃, time 30～45min; High-temperature roasting temperature (setting a little more than the EPS cracking temperature) is 860～900 ℃, time (30～45) min.

The invention has the beneficial effects as follows, adopt the composite shell of silicasol case and sodium silicate shell, keeping under the ceramic shell inner surface quality prerequisite, shortened the drying time of ceramic shell, reduce the sintering temperature of shell, thereby reduced the comprehensive manufacturing cost of shell.

The specific embodiment

The present invention's " disappearance mould composite ceramics shell casting technique " relates to outside known disappearance mould EPS manufacture craft, casting cleaning, Technology for Heating Processing and the patent 200810007693.1 described ceramic shell vacuum-assist pouring technologies, also comprises the manufacturing of composite ceramics shell, module roasting technique etc.

1, will organize the coating that the qualified disappearance mould EPS module of tree dips in (or spraying) Ludox and refractory powder allotments such as schmigel, zirconium English powder or mullite powder, spread corresponding refractory material fine sand, after the certain hour physical dryness, form ground floor silica sol ceramic mold shell;

2, the second layer is made sodium silicate shell, promptly is binding agent with waterglass, is preparation of powder coating with high alumina composite powder or other refractory materials etc., and sanding material can select for use certain order to count mullite sand or natural siliceous sand.After the hardening bath sclerosis, the physical dryness certain hour forms second layer waterglass ceramic shell.For the foundry goods below the 20KG, the waterglass ceramic shell applies 2 layers; For the foundry goods of macrostructure more, waterglass applies the corresponding increase of the number of plies.

3, make several layers composite ceramics shell and drying on request after, dip in waterglass at last once more and be coated with slip, physical dryness envelope slurry.

4, the dried module of envelope slurry is carried out preroast, pre-calcination temperature is 165～200 ℃ a little more than EPS mould condensing temperature, time 30～45min; And then carry out high-temperature roasting, the high-temperature roasting temperature is separated temperature a little more than the EPS mold crack, is 860～900 ℃, time (30～45) min.

5, the formwork after the high-temperature roasting is placed in the sandbox, the formwork main part is exposed cup by the vibration back-up sand, and sand must not enter formwork from cup; Sandbox surface coverage plastics mould is poured into formwork with molten metal liquid, opens sandbox simultaneously and takes out negative pressure device, closes when the formwork inner metal liquid begins conjunctiva and takes out negative pressure equipment.

6, behind the cooling forming, the sandbox mould turnover is isolated module and back-up sand.For back-up sand, the recovery of can sieving; For module, remove cast(ing) surface formwork and unnecessary running gate system.

7, foundry goods is put in storage through heat treatment, ball blast, pressure correction, machined and after examining eventually.

Claims

1. the accurate manufacturing process of the disappearance mould ceramic shell of an improvement is characterized in that following technology:

1, the shell that applies of disappearance mould (EPS mould) constitutes by two kinds of dissimilar fine casting shells are compound: ground floor is a silicasol case; The second layer is a sodium silicate shell.

2, the overall shell number of plies is less than known investment pattern precision casting technology and patent 200810007693.1 described technologies.The number of plies is 3～5 layers, specifically decides on part dimension; Except that ground floor was silicasol case, all the other were sodium silicate shell.

3, two stages of mould splits preroast and high-temperature roasting, wherein high-temperature roasting temperature is lower than patent 200810007693.1 described technologies.The module pre-calcination temperature is 165～200 ℃, time 30～45min; The high-temperature roasting temperature is 860～900 ℃, time (30～45) min.