CN102744368B - Method for maintaining viscosity of sizing agent for investment casting shell - Google Patents

Abstract

Disclosed is a method for maintaining viscosity of a sizing agent for an investment casting shell. The method includes steps of measuring actual measurement weight ratios of e, f and g of ingredients including water, a refractory matter and SiO2 in a sampled sizing agent before the viscosity of the sizing agent is adjusted by utilizing an ignition decrement method; setting objective values of the weight ratios of the three ingredients to be a, b and c respectively after the viscosity of the sizing agent is adjusted; calculating the total weight M of the sizing agent; setting the adding quantity of the water, silica solution and the refractory matter in the sizing agent to be X, Y and Z respectively under the condition that the weight ratio of the SiO2 in the silica solution is H; and solving a three-variable linear equation set with the known conditions to obtain the values of the X, the Y and the Z. The contents of the ingredients in the sizing agent can be adjusted in real time, and always keep in the objective values, the stability of the sizing agent is increased, the service life of the sizing agent is prolonged, and the method is beneficial to stabilizing an investment casting shell production process and the quality of products.

Description

The maintaining method of slurry viscosity for a kind of investment casting shell

Technical field

The present invention relates to the investment casting shell slurry, relate in particular to the maintenance of investment casting shell with slurry viscosity.

Background technology

Need to carry out Shell Preparation in the technological process of Investment Casting of Turbine Blade, its process is that turbo blade wax-pattern that compacting is completed is placed in slurry and is flooded, and makes slurry can stick to equably the surface of wax-pattern, forms shell after dry.Described slurry is the mixture system formed by refractory material, water and SiO2.In above-mentioned technical process, for the viscosity of slurry, there is very high requirement, require the viscosity of slurry to there is stationary value.At present, the maintaining method of slurry viscosity generally is divided into three kinds:

(1) add the water dilution when slurry viscosity is higher, with this, reduce the viscosity of slurry.

(2), when slurry viscosity is low, by the water evaporates in slurry, but this evaporation mode is consuming time longer, has a strong impact on production efficiency.

(3) content that adds Ludox to control SiO2 also can be adjusted the viscosity of slurry, but this control method is controlled the content of SiO2 only, can't learn the content of refractory material and water; After the content of SiO2 reaches technological requirement, if in slurry, water content is high, refractory material content is when low, can produce the dip coating drying not saturating, cause the turbine wax-pattern compactness deficiency with this coating, intensity is low; If the single refractory material that adds not only can make reduced water content, also can improve the viscosity of slurry.And when water content low, when refractory material content is high, can produce slurry viscosity higher, the coating layer thickness thickening, inconsistent through the rate of drying at each position of turbine wax-pattern of coating, produce stress concentrate and coating is torn, affect subsequent process steps.

Summary of the invention

The applicant, for above-mentioned shortcoming, provides the maintaining method of a kind of investment casting shell with slurry viscosity, has guaranteed that in slurry, each composition can be monitored and adjust.

The technical solution adopted in the present invention is as follows:

The maintaining method of slurry viscosity for a kind of investment casting shell, step is as follows:

The test of slurry sampling and minute content thereof for investment casting shell before the first step---viscosity is adjusted.

Investment casting shell before the viscosity adjustment is sampled with slurry, and the actual measurement weight accounting of utilizing calcination weight reduction and balance weighing measurement to go out water in described sampling slurry, refractory material, SiO2 composition is respectively e, f, g;

When the viscosity of second step---above-mentioned slurry is adjusted to desired value, the calculating of the setting of water, refractory material, SiO2 composition desired value and described composition addition X, Y, Z in slurry:

If the viscosity of above-mentioned slurry is adjusted to when suitable, in slurry, the desired value of water, refractory material, SiO2 composition weight accounting is respectively a, b, c; SiO2 wherein means the weight accounting of SiO2 in supernatant, and after described supernatant refers to slurry sediment, what sink to bottom is refractory material, and supernatant liquid is supernatant, comprising water and SiO2;

The gross weight of trying to achieve slurry is M;

In known Ludox, the weight accounting of SiO2 is H;

If in described slurry, the addition of water, Ludox, refractory material composition is respectively X, Y, Z, the value of described addition X, Y, Z is tried to achieve by following equation group and boundary condition thereof:

$\begin{array}{c}X=\frac{M*(1-f)*(g-c)+Y(H-c)}{c}\\ Y=(\mathrm{0,1,2,3},.....n)\end{array}$

$Z=\frac{M*(b-f)+\mathrm{bY}}{(1-b)}+\frac{b[M*(1-f)*(g-c)+Y(H-c)]}{(1-b)*c}$

X≥0

Z≥0。

When refractory material is the RBM200 trade mark, when the viscosity of described slurry is adjusted to desired value, in slurry, the desired value of water, refractory material, SiO2 composition weight accounting is respectively:

In slurry, the target range of the weight accounting a of water is 12.7-13.7%

In slurry, the target range of the weight accounting b of refractory material is 81.0-83.0%

In supernatant, the target range of the weight accounting c of SiO2 is 28.0-31.5%.

The target range of a/b/c is determined according to knowhow, this desired value difference of the refractory material of the different trades mark.

Beneficial effect of the present invention is as follows:

Can both carry out Real-Time Monitoring and control by this method to content, refractory material content and the water content of SiO2 in slurry, solved and just controlled the problem of single paste composition in the past, utilize equation group to try to achieve and need to ask the amount that adds composition, thereby adjust in real time the content of each composition in slurry, each component content in slurry is remained in desired value, improve the stability of slurry, extended the life-span of slurry, be beneficial to stablizing of investment casting casing production process and stablizing of product quality.

The specific embodiment

The following describes the specific embodiment of the present invention.

The maintaining method of a kind of slurry viscosity of the present invention comprises following concrete steps:

First step slurry sampling, by calcination weight reduction and balance weighing measurement, the actual measurement weight accounting that obtains water in slurry, refractory material, SiO2 is respectively e, f, g, and concrete steps are as follows:

1, get for the first time slurry sample: take with electronics sky chessboard the slurry sample mixed that weight is M1, in the time of 140 ℃, curing to measuring weight after constant weight is M2, and the weight of water is M1-M2

The weight accounting that can obtain water in slurry is:

$e=\frac{M1-M2}{M1}...\left(1\right)..$

2, get for the second time slurry sample: get again slurry sample, the method of separating fast by long-time natural sedimentation or use centrifuge, make slurry precipitate, after slurry sediment, by two parts, formed, a part is the refractory material that sinks to bottom, another part is supernatant liquid, and this part supernatant liquid is called supernatant.Supernatant is comprised of SiO2 and water.

Take with electronics sky chessboard the supernatant that weight is N1,140 ℃ cure to SiO2 weight in measuring supernatant after constant weight be N2, in supernatant, the weight of water is N1-N2, and in supernatant, the weight accounting of SiO2 is:

$g=\frac{N2}{N1}...\left(2\right)$

3,, for same slurry sample, be no matter in the slurry of sampling for the first time or, in the supernatant of sampling for the second time, the ratio of the weight of its water and the weight of SiO2 remains unchanged.The weight of setting SiO2 in the slurry sampled for the first time is M3, can obtain following equation:

The weight of SiO2 (sampling for the second time) in the weight/supernatant of water in supernatant

The weight of SiO2 (sampling for the first time) in the weight/slurry of water in=slurry

? $\frac{N1-N2}{N2}=\frac{M1-M2}{M3}$

Obtain $M3=\frac{M1-M2}{N1-N2}*N2$

Sample for the first time slurry and formed by water, SiO2 and refractory material three parts altogether, known water and SiO2 wherein, the weight M4 that tries to achieve refractory material is:

$M4=M1-(M1-M2)-M3=M2-\frac{M1-M2}{N1-N2}*N2$

In slurry, the weight accounting of refractory material is: $f=\frac{M2-\frac{M1-M2}{N1-N2}*N2}{M1}...\left(3\right)$

3, sampling for the third time, get the slurry sample of certain volume V and weigh, and obtaining weight is M5, calculates the density of slurry:

$\mathrm{\ρ}=\frac{M5}{V}$

Measure the height L of slurry in the radius R of slurry bucket and size barrel, the cumulative volume U=π R2*L that obtains slurry is the gross weight of whole bucket slurry:

$M=\mathrm{\ρ}*U=\frac{\mathrm{\π}{R}^2*L*M5}{V}...\left(4\right)$

By above calcination weight reduction and balance weighing measurement, and, by setting parameter and calculating, conclude the weight accounting value of the following parameter that obtains paste composition:

The weight accounting of water in slurry: $e=\frac{M1-M2}{M1}...\left(1\right)$

The weight accounting of refractory material in slurry: $f=\frac{M2-\frac{M1-M2}{N1-N2}*N2}{M1}...\left(3\right)$

SiO2 weight accounting in supernatant: $g=\frac{N2}{N1}...\left(2\right)$

The gross weight of whole bucket slurry: $M=\mathrm{\ρ}*U=\frac{\mathrm{\π}{R}^2*L*M5}{V}...\left(4\right)$

Second step safeguards that slurry viscosity is to desired value, need to add the calculating of composition and value thereof, and step is as follows:

1, setting composition and the value that need to add is respectively: the weight that adds water is X, and the weight of Ludox is Y, and the weight of refractory material is Z; Wherein Ludox is comprised of SiO2 and water, and the SiO2 weight accounting of establishing in Ludox wherein is H;

2,, after adding water, Ludox, refractory material, the content that calculates each composition of slurry is:

(1) gross weight of .SiO2 is: M* (1-f) * g+Y*H......................(5)

The weight accounting that the explanation of formula (5): M* (1-f) is water and SiO2 in supernatant, the weight that M* (1-f) * g is original SiO2 in slurry, Y*H adds the SiO2 weight increased after Ludox;

(2). the gross weight of water is: M*e+X+Y* (1-H) ... ... ... ... .(6)

The explanation of formula (6): the weight that M*e is slurry Central Plains water, X is the weight that adds water, Y*(1-H) for adding the weight of water in Ludox.

(3). the weight of refractory material is: M*f+Z......................(7)

The weight that the explanation of formula (7): M*f is original refractory material in slurry, Z is for being the weight that adds refractory material.

(4). the gross weight of slurry is: M+X+Y+Z......................(8)

(5). the gross weight of supernatant is: M* (1-f)+X+Y......................(9)

The explanation of formula (9): be M*(1-f) weight of original supernatant in slurry, X+Y is the weight that adds supernatant.

(6). after adding water, Ludox, refractory material, the accounting of each composition of slurry is:

3,, for safeguarding that slurry has appropriate viscosity, the desired value of setting water, refractory material, SiO2 in slurry is respectively: the weight accounting of water is a, and the weight accounting of refractory material is b, and in supernatant, the weight accounting of SiO2 is c, solves X, Y, Z value;

From the constituent of slurry, a, b, c meet relational expression

a+b+(1-b)*c=1......................（13）

The explanation of formula (13): (1-b) be the weight accounting (being the weight accounting that supernatant accounts for entire slurry) of water in slurry and SiO2, (1-b) no matter whether the weight accounting that * c is SiO2 in slurry (precipitate, the weight of SiO2 does not change, the weight of SiO2 in weight=slurry of SiO2 in supernatant);

If need to adjust to desired value to paste composition, according to formula (10)～(12), X, Y, Z must meet following equation group:

$\left\{\begin{array}{c}\frac{M*e+X+Y*(1-H)}{M+X+Y+Z}=a\\ \frac{M*f+Z}{M+X+Y+Z}=b\\ \frac{M*(1-f)*g+Y*H}{M*(1-f)+X+Y}=c\end{array}\right....\left(14\right)$

Suppose that the Ludox weight Y added is known quantity, according to the equation three of above-mentioned equation equation group (14)

$\frac{M*(1-f)*g+Y*H}{M*(1-f)+X+Y}=c$

Solve and obtain

$X=\frac{M*(1-f)*(g-c)+Y*(H-c)}{c}...\left(15\right)$

Again by the equation two of the above-mentioned equation equation group of the X substitution obtained (14)

$\frac{M*f+Z}{M+X+Y+Z}=b$

Solve and obtain

$Z=\frac{M(b-f)+\mathrm{bY}}{1-b}+\frac{b[M*(1-f)*(g-c)+Y*(H-c)]}{(1-b)*c}...\left(16\right)$

Therefore because slurry only has water, SiO2 and three kinds of compositions of refractory material, when the weight accounting of two compositions is wherein determined, the weight accounting of the third composition also can be determined.

And, in practical application, the solution obtained must be that nonnegative number is just meaningful, therefore makes Y=0,1,2,3,4 ... the natural number of n, when X and Z are nonnegative value, equation group (14) can obtain one group of solution.

In sum, the solving equation group of X, Y, Z value is:

$\left\{\begin{array}{c}X=\frac{M*(1-f)*(g-c)+Y*(H-c)}{c}\\ Y=\mathrm{0,1,2,3}....n\\ Z=\frac{M(b-f)+\mathrm{bY}}{1-b}+\frac{b[M*(1-f)*(g-c)+Y*(H-c)}{(1-b)*c}\\ X\≥0\\ Z\≥0\\ \end{array}\right....\left(17\right)$

Parameter in equation group (17) has: X, Y, Z; F, g; B, c.

From equation group (17): for safeguarding slurry, appropriate viscosity is arranged, adding the weight of water is X, and adding the weight of Ludox is Y, and the weight that adds refractory material is Z, and X, Y, Z are respectively the addition that the present invention will solve; F, g are respectively and utilize calcination weight reduction and balance weighing measurement to go out to add the actual measurement gravimetric value of refractory material, SiO2 in front slurry; B, c are respectively and safeguard that slurry has appropriate viscosity, set the desired value of refractory material, SiO2 in slurry; The weight accounting that H is SiO2 in added Ludox; M is the viscosity adjustment gross weight of slurry before;

That is: by the gross weight M of slurry before the viscosity adjustment,

Survey refractory material gravimetric value f, actual measurement SiO2 gravimetric value g before the viscosity adjustment in slurry,

Safeguard slurry viscosity, the desired value c of SiO2 in the desired value b of refractory material, supernatant in slurry,

The weight accounting H that adds SiO2 in Ludox,

And the weight Y that adds Ludox,

Can obtain the weight X that adds water and the weight Z that adds refractory material.

The specific embodiment of the invention process is as follows:

When refractory material be Continental Minerals produce the RBM200 trade mark time, the viscosity of described slurry is adjusted to when suitable, in slurry, the target range of water, refractory material, SiO2 composition weight accounting is respectively:

The target range 12.7-13.7% of the weight accounting a of water in slurry

The target range 81.0-83.0% of the weight accounting b of refractory material in slurry

The target range 28.0-31.5% of the weight accounting c of SiO2 in supernatant.

Embodiment 1

One barrel of slurry is arranged now, and measuring its density is 3.0g/ml, size barrel height L300mm, and size barrel radius 675mm, the SiO2 weight accounting H of the Ludox of selecting is that 30.0%(H is known parameter after outsourcing or autogamy silica sol liquid)

The parameter that its composition test obtains is respectively

The weight accounting e 13.02% of the water in slurry

The weight accounting f 81.00% of the refractory material in slurry

The weight accounting g 31.50% of SiO2 in supernatant

By above-mentioned parameter substitution solution set of equation, can be adjusted scheme, concrete computational process is as follows:

Can obtain the weight M of slurry according to size barrel height L, slurry proportion, size barrel radius, wherein ρ=3.0g/ml R=675mm=67.5cm L=300mm=30cm

M=ρ*π*R2*L=3.0*3.14*67.5*67.5*30=1287596.25g≈1287.5962kg

By the final computing formula of a=13.24% b=81.48% c=28.50% H=30.00% e=13.02% f=81.00%g=31.50% M=1287.5962 substitution, and make Y=0, draw:

$\left\{\begin{array}{c}X=\frac{1287.5962*(1-0.8100)*(0.3150-0.2850)+0*(0.3000-0.2850)}{0.2850}\≈25.751924\mathrm{kg}\≈26\mathrm{kg}\\ Y=0\\ Z=\frac{1287.5962(0.8148-0.8100)+0.8148*0}{1-0.8148}\\ +\frac{0.8148[1287.5962*(1-0.8100)*(0.3150-0.2850)+0*(0.3000-0.2850)]}{(1-0.8148)*0.2850}\≈146.6691\mathrm{kg}\≈147\mathrm{kg}\end{array}\right.$

Above-mentioned computing formula show that the amount of the supplementary material that need to add is distilled water 26kg thus, refractory material 147kg.

Concrete implementation and operation process is as follows:

Take out in part slurry to a to be adjusted slurry bucket, first add 26kg distilled water, use the hand-held quick mixer that slurry is stirred, add the 147kg refractory material with speed slowly, keep stirring until slurry stirs, finally the adjustment slurry be stirred is poured in size barrel to be adjusted.

Embodiment 2

One barrel of slurry is arranged now, and measuring its density is 2.9g/ml, size barrel height L450mm, and size barrel radius 675mm, the SiO2 weight accounting of the Ludox of selecting is 30.0%

The parameter that its composition test obtains is respectively:

The weight accounting 12.24% of the water in slurry

The weight accounting 83.00% of the refractory material in slurry

The weight accounting 28.00% of SiO2 in supernatant

By above-mentioned parameter substitution solution set of equation, can be adjusted scheme, concrete computational process is as follows:

Can obtain the weight M of slurry according to slurry height, slurry proportion, size barrel radius, wherein ρ=2.8g/ml R=675mm=67.5cm L=450mm=45cm

M=ρ*π*R2*L=2.8*3.14*67.5*67.5*45=1802634.75g≈1802.6348kg

By the final computing formula of a=13.24% b=81.48% c=28.50% H=30.00% e=12.24% f=83.00%g=28.00% M=1802.6348 substitution

Schilling Y=0, can be separated as follows:

$\left\{\begin{array}{c}X=\frac{1802.6348*(1-0.8300)*(0.2800-0.2850)+0*(0.3000-0.2850)}{0.2850}\≈-5.3763\mathrm{kg}\≈-5\mathrm{kg}\\ Y=0\\ Z=\frac{1802.6348(0.8148-0.8300)+0.8148*0}{1-0.8148}\\ +\frac{0.8148[1802.6348*(1-0.8300)*(0.2800-0.2850)+0*(0.3000-0.2850)]}{(1-0.8148)*0.2850}\≈-171.6017\mathrm{kg}\≈-172\mathrm{kg}\end{array}\right.$

Because above-mentioned negative solution does not have physical significance, can't realize.

Successively by Y=1,2,3 ... the substitution formula solves, when X and Z be on the occasion of the time physical significance that solved.

Omit Y=1,2,3 ... 92 process, when Y=93, X and Z are nonnegative value, and its solution is as follows:

$\left\{\begin{array}{c}X=\frac{1802.6348*(1-0.8300)*(0.2800-0.2850)+93*(0.3000-0.2850)}{0.2850}\≈-0.4814\mathrm{kg}\≈0\mathrm{kg}\\ Y=93\\ Z=\frac{1802.6348(0.8148-0.8300)+0.8148*93}{1-0.8148}\\ +\frac{0.8148[1802.6348*(1-0.8300)*(0.2800-0.2850)+93*(0.3000-0.2850)]}{(1-0.8148)*0.2850}\≈259.0937\mathrm{kg}\≈259\mathrm{kg}\end{array}\right.$

Show that by above-mentioned computing formula the amount of the supplementary material that need to add is Ludox 93kg, refractory material 259kg.

Concrete implementation and operation is as follows:

Choose a clean slurry bucket, add the Ludox of 93kg, the refractory material so that speed adds 259kg slowly, used hand-held quick mixer that slurry is stirred while adding refractory material.The adjustment slurry be stirred is the most at last poured in size barrel to be adjusted.

Above description is explanation of the invention, is not that limited range of the present invention is referring to claim, in the situation that, without prejudice to basic structure of the present invention, the present invention can do any type of modification to the restriction of invention.

Claims (2)

1. the maintaining method of slurry viscosity for an investment casting shell is characterized in that step is as follows:

The test of slurry sampling and minute content thereof for investment casting shell before the first step---viscosity is adjusted;

Investment casting shell before the viscosity adjustment is sampled with slurry, utilize calcination weight reduction and balance weighing measurement to go out water, refractory material, the SiO in described sampling slurry ₂the actual measurement weight accounting of composition is respectively e, f, g;

The viscosity of second step---above-mentioned slurry is adjusted to desired value, and the weight of each composition of needing in slurry to add is calculated:

If the viscosity of above-mentioned slurry is adjusted to when suitable, water, refractory material, SiO in slurry ₂the desired value of composition weight accounting is respectively a, b, c; SiO wherein ₂mean SiO in supernatant ₂the weight accounting, after described supernatant refers to slurry sediment, sink to bottom for refractory material, supernatant liquid is supernatant, comprising water and SiO ₂;

The gross weight of trying to achieve slurry is M;

In the setting slurry, needing to add the weight of water is the X kilogram, and the weight of Ludox is the Y kilogram, and the weight of refractory material is the Z kilogram;

?wherein Ludox is by SiO ₂form with water, establish the SiO in Ludox ₂the weight accounting is H; The value of above-mentioned addition X, Y, Z is tried to achieve by following equation group and boundary condition thereof:

2. the maintaining method with slurry viscosity by the described investment casting shell of claim 1, is characterized in that when refractory material is the RBM200 trade mark, when the viscosity of described slurry is adjusted to desired value, and water, refractory material, SiO in slurry ₂the desired value of composition weight accounting is respectively:

In slurry, the target range of the weight accounting a of water is 12.7-13.7%

In slurry, the target range of the weight accounting b of refractory material is 81.0-83.0%

SiO in supernatant ₂the target range of weight accounting c be 28.0-31.5%.