CN104325080B - A kind of shrinkage factor method for designing of leafy group of stator precision casting mould - Google Patents

Abstract

The invention discloses the shrinkage factor method for designing of a kind of leafy group of stator precision casting mould, by assuming that parameter, supposition shrinkage direction, shrinkage factor size are selected finally sets shrinkage factor；When manufacturing and designing Wax mold, three directions of L, D, R (shrinkage direction see supposition) that size differs greatly set corresponding shrinkage factor, solves the leafy group of guide vane overproof problem of foundry goods aisle spare because causing only with single shrinkage factor in the past。The present invention is applicable to all of leafy group of stator。Obtaining offset angle Δ α 1, Δ α 2 by the method calculated, solve the overproof problem of aisle spare, design concept and method are more reasonable。Design and produce mould " settling at one go ", greatly reduce product development expense, shorten the trial production cycle。And engineer applied can be promoted the use of。

Description

A kind of shrinkage factor method for designing of leafy group of stator precision casting mould

Technical field

The invention belongs to melted module precise casting technology field, particularly to the shrinkage factor method for designing of a kind of leafy group of stator precision casting mould。

Background technology

The establishing method of conventional leafy group of stator precision casting mould shrinkage factor is all adopt unified comprehensive shrinkage factor in a different direction。In actual production process, the shrinkage factor that the wax material of different length is corresponding is different, and traditional method is only applicable to the foundry goods that dimensional structure in all directions is more or less the same。

For leafy group of guide vane of ultra-fine length, dimensional structure differs greatly in different directions, and the method adopting single integrated shrinkage factor is irrational, causes that casting dimension is overproof。Under ensureing the premise of pipes' analysis size and blade molding surface size, foundry goods aisle spare can be caused bigger than normal。The mould done cannot be reprocessed, and redesigns die module only by the method slowly debugged or redesigns mould to solve this kind of overproof problem, extends mould shape and product development cycle and add development cost。

Summary of the invention

It is an object of the invention to solve the problems referred to above, the shrinkage factor method for designing of a kind of leafy group of stator precision casting mould is provided, when adopting the method to manufacture and design Wax mold, three directions of L, D, R (shrinkage direction see supposition) that size differs greatly set corresponding shrinkage factor, solves the leafy group of guide vane overproof problem of foundry goods aisle spare because causing only with single shrinkage factor in the past。

To achieve these goals, the technical solution adopted in the present invention comprises the following steps:

1) parameter is assumed

It is assumed that a kind of leafy group of guide vane has K blade, the radius respectively R of supramarginal plate and inframarginal place circumference₂And R₁, the width of supramarginal plate and inframarginal is D, and two interlobate angles are α, and (K-1) α < 45 °；

2) shrinkage direction is supposed

Dimensional structure feature according to leafy group of guide vane, assuming that the shrinkage direction of leafy group of guide vane is divided into L direction, D direction and R direction, wherein, L direction is the radian direction of upper and lower listrium, D direction is the width of upper and lower listrium, and R direction is the length direction of blade；

3) shrinkage factor size is selected

Characteristic according to wax material on-the-spot in actual production process, different length selects corresponding shrinkage factor；

4) shrinkage factor sets

When designing and producing leafy group of stator precision casting mould, the contraction in all directions sets respectively in the following manner:

On D direction: upper and lower listrium width amplifies ψ 4；

On R direction: blade length direction amplifies ψ₁, i.e. R₁Become (1+ ψ₁)R₁, R₂Become (1+ ψ₁)R₂, interlobate angle α is constant；

On L direction: make the central axis of leafy group of guide vane overlap with coordinate axes Z axis before amplification, supramarginal plate radian direction is amplified ψ₂, inframarginal radian direction is amplified ψ₃；

If AB represents the central axis of leafy group of guide vane, overlap with coordinate axes Z axis；A₁B₁Represent a blade in leafy group of guide vane after amplifying on R direction；β represents A₁B₁The angle of the blade on direction and leafy group of guide vane central axis；A₁′B₁' represent blade A₁B₁Size shape after amplifying in the l-direction；Calculate inframarginal A₁After point amplifies in the l-direction, from A₁To A₁' angle of eccentricity Δ α₁And supramarginal plate B₁After point amplifies in the l-direction, from B₁To B₁' angle of eccentricity Δ α₂。

Described step 3) in, the corresponding shrinkage factor of different length is:

Length of blade L=R₂-R₁, corresponding shrinkage factor is ψ₁；

Supramarginal plate arc length L₂=K α R₂, corresponding shrinkage factor is ψ₂；

Inframarginal arc length L₁=K α R₁, corresponding shrinkage factor is ψ₃；

Upper and lower listrium width is D, and corresponding shrinkage factor is ψ₄。

Described step 4) in, the concrete grammar calculating sum is:

Calculate Δ α₁With Δ α₂, by

$\frac{(\mathrm{\&beta;}+\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1)\&times;(1+{\mathrm{\&psi;}}_1)\&times;R_1-\mathrm{\&beta;}\&times;R_1}{\mathrm{\&beta;}{R}_1}={\mathrm{\&psi;}}_3---\left(1\right)$

$\frac{(\mathrm{\&beta;}+\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2)\&times;(1+{\mathrm{\&psi;}}_1)\&times;R_2-\mathrm{\&beta;}\&times;R_2}{\mathrm{\&beta;}{R}_2}={\mathrm{\&psi;}}_2---\left(2\right)$

?

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&beta;}---\left(3\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&beta;}---\left(4\right)$

When K is odd number, A₁′B₁' represent first blade, the then β=α of adjacent AB

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&alpha;}---\left(5\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&alpha;}---\left(6\right)$

A₁′B₁' when representing the n-th blade of adjacent AB, β=N α

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{N\&alpha;}---\left(7\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{N\&alpha;}---\left(8\right)$

When K is even number, A₁′B₁' represent the n-th blade of adjacent AB, then β=N α-α/2

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}(\mathrm{N\&alpha;}-\frac{\mathrm{\&alpha;}}{2})---\left(9\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}(\mathrm{N\&alpha;}-\frac{\mathrm{\&alpha;}}{2})---\left(10\right)$

Can be obtained by formula (7), (8), (9) and (10):

Work as ψ₁=ψ₂=ψ₃Time, namely unified by their entirety comprehensive shrinkage factor sets mould, △ α₁=△ α₂=0, at this moment blade angle does not have biasing；

Work as ψ₂=ψ₃Time, △ α₁=△ α₂, the length of blade of done mould is isometric。

Compared with prior art, the method have the advantages that

When adopting the inventive method to manufacture and design Wax mold, three directions of L, D, R (shrinkage direction see supposition) that size differs greatly set corresponding shrinkage factor, solves the leafy group of guide vane overproof problem of foundry goods aisle spare because causing only with single shrinkage factor in the past。The present invention is applicable to all of leafy group of stator。Offset angle Δ α is obtained by the method calculated₁、Δα₂, solving the overproof problem of aisle spare, design concept and method are more reasonable。Design and produce mould " settling at one go ", greatly reduce product development expense, shorten the trial production cycle。And engineer applied can be promoted the use of。

Accompanying drawing explanation

Fig. 1 is the shrinkage direction schematic diagram that current invention assumes that；

Fig. 2 is the bias conditions schematic diagram of supramarginal plate and inframarginal after amplifying by different shrinkage factors on L direction of the present invention。

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is further detailed explanation:

The concrete setting principle of shrinkage factor of the present invention and method are as follows

(1) leafy group of stator basic condition

It is assumed that a kind of leafy group of guide vane has K blade, the radius respectively R of upper and lower listrium place circumference₂、R₁, upper and lower listrium width is D, and two interlobate angles are α, and (K-1) α < 45 °。

(2) shrinkage direction is supposed

As shown in Figure 1, dimensional structure feature according to leafy group of guide vane, it is assumed that the shrinkage direction of leafy group of guide vane is divided into three direction: L (upper and lower listrium radian direction), D (upper and lower listrium width), R (length of blade direction)。

The shrinkage direction schematic diagram that Fig. 1 supposes

(3) shrinkage factor size is selected

Characteristic according to wax material on-the-spot in actual production process, different length selects different shrinkage factor:

Length of blade L=R₂-R₁, corresponding shrinkage factor is ψ₁；

Supramarginal plate arc length L₂=K α R₂, corresponding shrinkage factor is ψ₂；

Inframarginal arc length L₁=K α R₁, corresponding shrinkage factor is ψ₃；

Upper and lower listrium width is D, and corresponding shrinkage factor is ψ 4。

(4) shrinkage establishing method:

Conventional shrinkage factor establishing method:

Leafy group of guide vane, i.e. ψ for ultra-fine length₁> ψ₂, ψ₁> ψ₃, ψ₁> ψ₄。

1) with ψ₂、ψ₃Or ψ₄During as whole synthesis shrinkage factor, foundry goods R direction size is less than normal, it is impossible to ensure blade passage face V spot size and aisle spare。

2) with maximum ψ₁Set as comprehensive shrinkage factor, it is possible to meeting R direction dimensional requirement, L direction size is bigger than normal, and foundry goods aisle spare is bigger than normal。

Solution:

Again make mould, according to the aisle spare pouring into a mould out foundry goods situation bigger than normal, bias blade, by less than normal for α value。

Existing shrinkage factor establishing method:

When designing and producing leafy group of stator precision casting mould, the contraction in all directions is implemented respectively in the following manner:

On D direction: upper and lower listrium width amplifies ψ₄。

On R direction: blade length direction amplifies ψ₁, i.e. R₁Become (1+ ψ₁)R₁, R₂Become (1+ ψ₁)R₂, interlobate angle α is constant。

On L direction:

As in figure 2 it is shown, must assure that the central axis of leafy group of guide vane overlaps with coordinate axes Z axis before amplifying, supramarginal plate radian direction is amplified ψ₂, inframarginal radian direction is amplified ψ₃, the biasing that the result of amplification is by leaf angle shows。

If AB represents the central axis of leafy group of guide vane, overlap with coordinate axes Z axis。A₁B₁Represent a blade in leafy group of guide vane after amplifying on R direction。β represents A₁B₁The angle of the blade on direction and leafy group of guide vane central axis。A₁′B₁' represent blade A₁B₁Size shape after amplifying in the l-direction。Δ α₁Represent inframarginal A₁After point amplifies in the l-direction, from A₁To A₁' angle of eccentricity。Δ α₂Represent supramarginal plate B₁After point amplifies in the l-direction, from B₁To B₁' angle of eccentricity。

As seen from Figure 2, Δ α₁、Δα₂It is calculative value, and works as ψ₂With ψ₃When value differs, the length of blade Length discrepancy of done mould, blade is more remote from AB, biases more big, and blade is more long。

Calculate Δ α₁、Δα₂, by

$\frac{(\mathrm{\&beta;}+\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1)\&times;(1+{\mathrm{\&psi;}}_1)\&times;R_1-\mathrm{\&beta;}\&times;R_1}{\mathrm{\&beta;}{R}_1}={\mathrm{\&psi;}}_3---\left(1\right)$

$\frac{(\mathrm{\&beta;}+\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2)\&times;(1+{\mathrm{\&psi;}}_1)\&times;R_2-\mathrm{\&beta;}\&times;R_2}{\mathrm{\&beta;}{R}_2}={\mathrm{\&psi;}}_2---\left(2\right)$

?

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&beta;}---\left(3\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&beta;}---\left(4\right)$

When K is odd number, A₁′B₁' represent first blade, the then β=α of adjacent AB

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&alpha;}---\left(5\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&alpha;}---\left(6\right)$

A₁′B₁' when representing the n-th blade of adjacent AB, β=N α

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{N\&alpha;}---\left(7\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{N\&alpha;}---\left(8\right)$

When K is even number, A₁′B₁' represent the n-th blade of adjacent AB, then β=N α-α/2

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}(\mathrm{N\&alpha;}-\frac{\mathrm{\&alpha;}}{2})---\left(9\right)$

$\mathrm{\&Delta;}{\mathrm{\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}(\mathrm{N\&alpha;}-\frac{\mathrm{\&alpha;}}{2})---\left(10\right)$

Can be obtained by formula (7), (8), (9) and (10):

Work as ψ₁=ψ₂=ψ₃Time, namely unified by their entirety comprehensive shrinkage factor sets mould, △ α₁=△ α₂=0, at this moment blade angle does not have biasing；

Work as ψ₂=ψ₃Time, △ α₁=△ α₂, the length of blade of done mould is isometric。

(5) comparison of conventional shrinkage factor establishing method and existing shrinkage factor establishing method, referring to table 1:

The comparison table of the conventional shrinkage factor establishing method of table 1 and existing shrinkage factor establishing method

Embodiment 1: five leaf group Pyatyi guide vane

(1) certain five leaf group guide vane overall size:

Supramarginal plate arc length L₂Being approximately 140mm, inframarginal arc length L1 and be approximately 90mm, upper and lower listrium width D is about 30mm～40mm, blade length L=R₂-R₁It is approximately 220mm, vane group total radian 4 α=16.3636 °。

(2) selected contraction size

Characteristic according to wax material on-the-spot in actual production process, dimensions length is that 90mm～140mm casting die shrinkage factor adopts 2.1%, and length is that 30mm～40mm adopts 2%, and length is that 220mm adopts 2.4%。

That is, ψ₁=2.4%, ψ₂=ψ₃=2.1%, ψ₄=2%。

(3) mold shrinkage design

On D direction: upper and lower listrium width amplifies 2%。

On R direction: blade length direction amplifies 2.4%, i.e. R₁Become 1.024R₁, R₂Become 1.024R₂, interlobate angle 4.0909 ° is constant。

On L direction: ensure before amplification that the central axis of leafy group of guide vane overlaps with coordinate axes Z axis。By calculating, offset angleWhen N is 1, △ α=-43 ", when N is 2, △ α=-86 "。That is, it is centrally located the blade of axle both sides, biases 43 respectively successively to central axis direction ", 86 "。

In order to make it easy to understand, above-mentioned shrinkage factor amplification process can so describe: ensure under the premise that the central axis of leafy group of guide vane overlaps with coordinate axes Z axis, overall amplifying 2.4%, then axis both sides blade biases 43 ", 86 " to central axis direction successively。Finally, upper and lower listrium width reduces 2.4%-2%=0.4%。

Three grades of guide vanes of embodiment 2: five leaf group

(1) certain three grades of guide vane overall size of five leaf groups

Supramarginal plate arc length L₂Being approximately 145mm, inframarginal arc length L1 and be approximately 90mm, upper and lower listrium width D is about 20mm～40mm, blade length L=R₂-R₁It is approximately 180mm, vane group total radian 4 α=17.1429 °。

(2) selected contraction size

Characteristic according to wax material on-the-spot in actual production process, dimensions length is that 90mm～145mm casting die shrinkage factor adopts 2.1%, and length is that 20mm～40mm adopts 2%, and length is that 180mm adopts 2.3%。

That is, ψ₁=2.3%, ψ₂=ψ₃=2.1%, ψ₄=2%。

(3) mold shrinkage design

By calculating, offset angleWhen N is 1, △ α=-30 ", when N is 2, △ α=-60 "。

Shrinkage factor amplification process: ensure under the premise that the central axis of leafy group of guide vane overlaps with coordinate axes Z axis, overall amplifies 2.3%, and then axis both sides blade biases 30 ", 60 " to central axis direction successively。Finally, upper and lower listrium width reduces 0.3%。

Embodiment 3: five leaf group level Four guide vane

(1) certain five leaf group level Four guide vane overall size

Supramarginal plate arc length L₂It is approximately 145mm, inframarginal arc length L₁Being approximately 85mm, upper and lower listrium width D is about 20mm～40mm, blade length L=R₂-R₁It is approximately 200mm, vane group total radian 4 α=16.3636 °。

(2) selected contraction size

Characteristic according to wax material on-the-spot in actual production process, dimensions length is that 85mm～145mm casting die shrinkage factor adopts 2.1%, and length is that 20mm～40mm adopts 2%, and length is that 200mm adopts 2.4%。

That is, ψ₁=2.4%, ψ₂=ψ₃=2.1%, ψ₄=2%。

(3) mold shrinkage design

By calculating, offset angleWhen N is 1, △ α=-43 ", when N is 2, △ α=-86 "。

Shrinkage factor amplification process: ensure under the premise that the central axis of leafy group of guide vane overlaps with coordinate axes Z axis, overall amplifies 2.4%, and then axis both sides blade biases 43 ", 86 " to central axis direction successively。Finally, upper and lower listrium width reduces 0.4%。

Adopt above three embodiment to five leaf groups three, four, the mold shrinkage of Pyatyi guide vane is set, aisle spare dimension overproof problem is solved, Design of Dies makes " settling at one go ", greatly reduces product development expense, shortens the trial production cycle。

Above content is only the technological thought that the present invention is described, it is impossible to limits protection scope of the present invention, every technological thought proposed according to the present invention, any change done on technical scheme basis with this, each falls within the protection domain of claims of the present invention。

Claims (2)

1. the shrinkage factor method for designing of a leafy group of stator precision casting mould, it is characterised in that comprise the following steps:

1) parameter is assumed

It is assumed that a kind of leafy group of guide vane has K blade, the radius respectively R of supramarginal plate and inframarginal place circumference₂And R₁, the width of supramarginal plate and inframarginal is D, and two interlobate angles are α, and (K-1) α < 45 °；

2) shrinkage direction is supposed

Dimensional structure feature according to leafy group of guide vane, assuming that the shrinkage direction of leafy group of guide vane is divided into L direction, D direction and R direction, wherein, L direction is the radian direction of upper and lower listrium, D direction is the width of upper and lower listrium, and R direction is the length direction of blade；

3) shrinkage factor size is selected

Characteristic according to wax material on-the-spot in actual production process, different length selects corresponding shrinkage factor；

4) shrinkage factor sets

When designing and producing leafy group of stator precision casting mould, the contraction in all directions sets respectively in the following manner:

On D direction: upper and lower listrium width amplifies ψ₄；

On R direction: blade length direction amplifies ψ₁, i.e. R₁Become (1+ ψ₁)R₁, R₂Become (1+ ψ₁)R₂, interlobate angle α is constant；

On L direction: make the central axis of leafy group of guide vane overlap with coordinate axes Z axis before amplification, supramarginal plate radian direction is amplified ψ₂, inframarginal radian direction is amplified ψ₃；

If AB represents the central axis of leafy group of guide vane, overlap with coordinate axes Z axis；A₁B₁Represent a blade in leafy group of guide vane after amplifying on R direction；β represents A₁B₁The angle of the blade on direction and leafy group of guide vane central axis；A₁′B₁' represent blade A₁B₁Size shape after amplifying in the l-direction；Calculate inframarginal A₁After point amplifies in the l-direction, from A₁To A₁' angle of eccentricity Δ α₁And supramarginal plate B₁After point amplifies in the l-direction, from B₁To B₁' angle of eccentricity Δ α₂；

Calculate Δ α₁With Δ α₂Concrete grammar be:

Δα₁With Δ α₂, by

$\frac{(\mathrm{\&beta;}+{\mathrm{\&Delta;\&alpha;}}_1)\&times;(1+{\mathrm{\&psi;}}_1)\&times;R_1-\mathrm{\&beta;}\&times;R_1}{{\mathrm{\&beta;R}}_1}={\mathrm{\&psi;}}_3---\left(1\right)$

$\frac{(\mathrm{\&beta;}+{\mathrm{\&Delta;\&alpha;}}_2)\&times;(1+{\mathrm{\&psi;}}_1)\&times;R_2-\mathrm{\&beta;}\&times;R_2}{{\mathrm{\&beta;R}}_2}={\mathrm{\&psi;}}_2---\left(2\right)$

?

${\mathrm{\&Delta;\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&beta;}---\left(3\right)$

${\mathrm{\&Delta;\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&beta;}---\left(4\right)$

When K is odd number, A₁′B₁' represent first blade, the then β=α of adjacent AB

${\mathrm{\&Delta;\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&alpha;}---\left(5\right)$

${\mathrm{\&Delta;\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}\mathrm{\&alpha;}---\left(6\right)$

A₁′B₁' when representing the n-th blade of adjacent AB, β=N α

${\mathrm{\&Delta;\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}N\mathrm{\&alpha;}---\left(7\right)$

${\mathrm{\&Delta;\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}N\mathrm{\&alpha;}---\left(8\right)$

When K is even number, A₁′B₁' represent the n-th blade of adjacent AB, then β=N α-α/2

${\mathrm{\&Delta;\&alpha;}}_1=\frac{{\mathrm{\&psi;}}_3-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}(N\mathrm{\&alpha;}-\frac{\mathrm{\&alpha;}}{2})---\left(9\right)$

${\mathrm{\&Delta;\&alpha;}}_2=\frac{{\mathrm{\&psi;}}_2-{\mathrm{\&psi;}}_1}{1+{\mathrm{\&psi;}}_1}(N\mathrm{\&alpha;}-\frac{\mathrm{\&alpha;}}{2})---\left(10\right)$

Can be obtained by formula (7), (8), (9) and (10):

Work as ψ₁=ψ₂=ψ₃Time, namely unified by their entirety comprehensive shrinkage factor sets mould, Δ α₁=Δ α₂=0, at this moment blade angle does not have biasing；

Work as ψ₂=ψ₃Time, Δ α₁=Δ α₂, the length of blade of done mould is isometric。

2. the shrinkage factor method for designing of leafy group of stator precision casting mould according to claim 1, it is characterised in that: described step 3) in, the corresponding shrinkage factor of different length is:

Length of blade L=R₂-R₁, corresponding shrinkage factor is ψ₁；

Supramarginal plate arc length L₂=K α R₂, corresponding shrinkage factor is ψ₂；

Inframarginal arc length L₁=K α R₁, corresponding shrinkage factor is ψ₃；

Upper and lower listrium width is D, and corresponding shrinkage factor is ψ₄。