CN101417396A - Turbine hollow blade rabbet processing locating clamping method and device - Google Patents

Abstract

The invention discloses a positioning and clamping method and a fixture for processing a tenon of a turbine hollow blade. In selecting the positioning point, the clamp precision theory based on differential geometry and the form-closed criterion of the positioning point are adopted. Select the optimal five positioning points, so that when using six points including the reference point for positioning, the positioning accuracy of the blade is the highest; in the selection of the clamping point, avoid weak links, and select the auxiliary clamping point at the rigidity The top of the tenon and the blade mounting plate with a better and larger area minimize the force and deformation of the hollow blade body. On this basis, a special fixture for blade tenon processing is designed, which consists of the fixture main body, positioning pins, tenon top auxiliary fixtures, and blade mounting plate auxiliary fixtures. The fixture can ensure accurate positioning and effective clamping in the processing of hollow turbine blade tenons, and can improve efficiency, reduce costs and eliminate human health hazards in the processing of hollow blades with complex curved surfaces.

Description

Hollow Turbine Blade Tenon Machining Positioning Clamping Method and Fixture

technical field

The invention belongs to a machining and positioning method for turbine blades and a special fixture design, in particular to a positioning and clamping method and a fixture for machining the tenon of a hollow moving blade of a gas turbine turbine.

Background technique

A gas turbine is a rotary impeller power mechanical device that converts the heat energy generated by the combustion of gas or liquid fuel (such as natural gas, fuel oil) into mechanical work. It is widely used in energy, aviation, transportation, national defense and other fields. And the key major equipment for the development of aviation industry. The high-temperature turbine blade is the part with the highest temperature (above 1400°C), the most complex stress, and the harshest environment in the gas turbine. Its value accounts for nearly 50% of the whole product and is a key component in the gas turbine. The use of cooling blade structure is the most effective measure to improve the efficiency of gas turbines. At present, the high-temperature stage moving blades of turbines mostly adopt cooling structures with special-shaped hole cooling channels inside the blade body and densely distributed small holes on the surface of the blade body, especially on the intake side. Since the curved surface of the blade body is relatively complex and hollow as a whole, how to ensure accurate positioning and reasonable clamping in the machining of the blade becomes the key to ensure the service life of the blade in harsh environments such as high temperature and high speed rotation.

At present, in the processing of blade tenons, most engine manufacturers follow a processing and production method: that is, use low-temperature alloy containing box-shaped fixtures to process blades with complex curved surfaces. This process selects the positioning point on the blade based on experience, and after positioning the blade with a box-shaped fixture, pours the low melting point alloy into the gap between the box and the blade to form a whole, and uses the regular shape of the box for clamping and processing , so as to avoid the force on the blade body and achieve the purpose of precise machining. There are many advantages in using low-temperature alloy containing box method to process blade tenons, such as accurate positioning, no special requirements for processing force in the processing process, and stable clamping. However, its disadvantages are also obvious. Because the low melting point alloy used is toxic to the human body, it will cause great damage to the health of the operating workers in the long run. At the same time, the low-temperature alloy containing box-shaped fixture has relatively low processing efficiency, relatively long production cycle, and very high cost, which restricts large-scale processing and production of blades.

Contents of the invention

In order to overcome the shortcomings of the existing low-temperature alloy containing box method, the present invention proposes a new machining, positioning and clamping method and fixture for hollow turbine blade tenons. This method is based on the fixture accuracy theory of differential geometry and the shape-closed theory of positioning, selects five positioning points with the highest blade positioning accuracy during tenon processing, and selects the auxiliary clamping point at the top of the tenon and the side of the blade mounting plate, so that the blade will The positioning accuracy and force deformation are controlled at the same time, and on this basis, a special fixture for machining the tenon of the turbine hollow blade is designed.

To achieve the above object, the present invention is achieved by taking the following technical solutions:

A method for positioning and clamping the tenon of a turbine hollow blade, including the selection of the positioning point of the blade profile, the positioning and clamping of the blade profile according to the selected positioning point, and the auxiliary clamping of the top of the tenon of the blade and the blade mounting plate; For the selection of surface positioning points, first select a fifth positioning point on the upper side of the blade of the blade mounting plate as a reference point, and then use the given blade surface design data to establish a precision-constrained mathematical model of the blade positioning point; obtain the selected positioning point The point set space, and then determine the optimal criterion for selecting the positioning point based on the best position accuracy; then determine the optimization constraints according to the shape closure requirements of the positioning point; finally, optimize and determine the five positioning points of the blade profile: the first above to the fourth positioning point and the sixth positioning point below; arrange the first to sixth positioning pins on the fixture body according to the determined first to sixth positioning points, so that the round heads of the six positioning pins are respectively located at the sixth positioning point of the blade. The normal direction of the first to the sixth positioning point ensures that after the blade is placed and in contact with the positioning pin, the positioning pin is perpendicular to the tangent plane of the blade positioning point; The tenon end face uses the tenon end face auxiliary clamp separated from the main body of the clamp to clamp the blade left and right; on the upper and lower sides of the blade mounting plate, the mounting plate auxiliary clamp integrated with the main body of the clamp is used to clamp the blade up and down.

In the above method, the selection of the positioning point of the blade profile adopts the following specific steps:

The first step, according to the relationship between the workpiece position error and the positioning point error, that is, the normal vector of the positioning point and the contact point of the workpiece is n _i , and the coordinate of the contact point is R _i , then the position disturbance of any point of the workpiece δq={δb, δθ} The position error of the positioning point is ${\mathrm{\δy}}_i=h_i^T\mathrm{\δq},$ in $h_i^T=-\left\{{\mathrm{no}}_i^T{(R_i\×{\mathrm{no}}_i)}^T\right\}$ is the position vector of the positioning point; therefore, the precision constraint of the fixture with l positioning points, that is, the position error of the positioning point can be expressed as: δy=G ^T δq, where: δy={δy ₁ , δy ₂ ,..., δy _l }, G=[h ₁ , h ₂ ,...,h _l ] is the positioning point position matrix, and each positioning point position matrix G corresponds to a given fixture positioning point distribution;

In the second step, the position coordinates of the feature points on the blade surface are provided in the blade model, and the position coordinates of the feature points are fitted by bicubic B-splines to obtain the control nodes of the blade surface expressed by the B-splines; according to the obtained B-spline The surface control node is used to calculate the normal vector of the feature points on the blade surface, so as to obtain the point set space g _i =[R _i n _i ](1≤i≤N) of the selected anchor points;

Step 3: Assume that the error of each positioning point obeys a normal distribution: δy≈N(0, V _y ), where V _y =diag{δ ₁ , δ ₂ ...δ _l }, the position variance matrix of the positioning point for $V=\mathrm{Var}\left(\mathrm{\δq}\right)={\left({\mathrm{GV}}_{\mathrm{the\; y}}^{-1}{G}^T\right)}^{-1},$ Assuming A=V ^-1 , the condition for making the position accuracy of the workpiece the best is max(det A); since the material properties of each positioning element are the same, the δy _i of different positioning points obey the same distribution δy _i ≈ N(0 , V _y ), then there is

$V={\left({\mathrm{GV}}_{\mathrm{the\; y}}^{-1}{G}^T\right)}^{-1}={\left(\mathrm{G\δ}{G}^T\right)}^{-1},$ A=V ^-1 =GδG ^T =δGG ^T ,

Therefore, the best optimization criterion for workpiece position accuracy is: max(det A)=max(det(GG ^T ));

Step 4: For a given fixture positioning point position matrix G=[h ₁ , h ₂ , ..., h _l ], when any external force acts on the workpiece, the position of the fixture positioning point does not change, and at each positioning point There is a normal positive force acting on the point, then the anchor point position matrix G=[h ₁ , h ₂ ,...,h _l ] in this state satisfies the form closure. Then select a position vector h _c arbitrarily in the anchor point position matrix G, and apply any external force along its normal direction. For all h _i , α _i =-h _i ^T A ^-1 h _c should satisfy a _i >0;

Step 5: In the point set space g _i =[R _i n _i ](1≤i≤N) of the feature points of the blade profile, with max(det A) as the optimization criterion, under the constraint condition a _i >0 Optimal selection of five positioning points with the highest precision, the specific steps are as follows:

a. Initialize, calculate the position vector h ₀ of the determined positioning point on the blade mounting plate, and calculate the direction vectors of all N points in the point set g _i =[R _i n _i ](1≤i≤N), for The positioning point position matrix G ₀ is initialized; G ₀ = {h ₀ h ₁ ... h _N } is obtained, where h ₀ is the determined positioning point, and the corresponding A ₀ and A ₀ ^-1 are calculated; then at the positioning point position Randomly select a position vector h _c in the matrix G ₀ , apply any external force along its normal direction, for a given h _i (1≤i≤N), calculate α _i =-h _i ^T A ₀ ^-1 h _c , and Let k = N;

b. If there are anchor points that do not satisfy the shape closure, delete the point j that makes p _j = h _j ^T A _m ^-1 h _j (m=Nk) the smallest among these points; if all the anchor points satisfy the shape closure condition, then directly delete the anchor point j that makes p _j =h _j ^T A _m ^-1 h _j (m=Nk) the smallest, and make k=k-1;

c. Reorder the point set, the new point set becomes g _i ＝[R _i n _i ](1≤i≤k), update G _m ＝{h ₀ h ₁ ...h _k }, A _m , A _m ^-1 and α _i =-h _i ^T A _m ^-1 h _c (m=Nk), then repeat step b, and so on until k=5.

A fixture for realizing the aforementioned method, comprising a fixture main body, characterized in that the fixture main body is connected with an auxiliary fixture for a mounting plate for clamping the blade up and down; the fixture main body is provided with first to sixth positioning points of corresponding blades to the sixth positioning pin, so that the round heads of the six positioning pins are respectively located in the normal direction of the first to sixth positioning points of the blade, to ensure that after the blade is put in and in contact with the positioning pin, the positioning pin is perpendicular to the tangent plane of the blade positioning point; The main body of the clamp is also provided with a clamping pin, which clamps the blade left and right together with a mortise end surface auxiliary clamp separated from the main body of the clamp.

In the above fixture scheme, the tenon end face auxiliary fixture of the blade and the auxiliary fixture of the mounting plate are provided with an adjustable and adaptive contact designed auxiliary fixture, the auxiliary fixture includes a head and a rod, the upper plane of the head is in contact with the Workpiece contact, internal planes in contact with the spherical surface at the top of the stem. The rod is provided with threads, which can cooperate with the tenon end surface of the blade and the auxiliary clamp of the mounting plate to realize position adjustment.

The advantages of the present invention are: the theory of fixture accuracy based on differential geometry and the shape-closed constraints of the positioning points are proposed, and the optimal five positioning points are selected on the blade with the help of the three-dimensional model of the blade surface, so that the six positioning points including the reference point can be used. When locating at one positioning point, the positioning accuracy of the blade is the highest; in the selection of the clamping point, try to avoid the weak link, and select the auxiliary clamping point on the top of the tenon and the blade mounting plate at the transition part of the blade profile and the tenon, as far as possible Reduce the force and deformation of the hollow blade body; on this basis, a special fixture for the tenon processing of the turbine hollow blade is designed. The fixture has a round head positioning pin perpendicular to the positioning plane, a fine thread Auxiliary fixtures and fixtures with self-adaptive contact design can ensure the mutual cooperation between fixtures and fixtures, and can meet the requirements of accurate positioning and effective clamping in the machining of tenons of turbine hollow blades.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Figure 1 shows the blade structure. The hollow turbine blade includes a tenon 14, a mounting plate 15 and a blade profile 16. The blade is hollow and has complex cooling channels inside. The tenon 14 is the installation reference of the blade on the turbine.

Fig. 2 is a schematic diagram of six positioning points of the blade. One of the positioning points d5 is in the middle of the mounting plate 15 near the blade profile, and five positioning points d1, d2, d3, d4 (above) and d6 (below) obtained by optimization are on the blade profile 16 .

Fig. 3 is a structure diagram of the fixture of the present invention. Figure 3(a) shows the clamp body 10 and related positioning and clamping elements on it, including positioning pins 1, 2, 3, 4, corresponding to the blade profile positioning points d1, d2, d3, d4, d6, 6. Blade top clamp pin 7, clips 9, 11, 12, 13 on the blade mounting plate auxiliary fixture 8; Fig. 3(b) is the tenon end surface auxiliary fixture 19 and the clips 20, 21 on it.

FIG. 4 is a schematic diagram of the connection between the clip and the blade mounting plate of the auxiliary fixture of the blade mounting plate in FIG. 3 .

FIG. 5 is a schematic structural view of the clip in FIG. 3 and FIG. 4 . Among the figure, 17 is the head of the clip, and 18 is the rod of the clip. The upper plane of the head 17 is in contact with the workpiece, and the inner plane is in contact with the spherical surface at the top of the rod 18, allowing a certain angle error between the contact surface of the workpiece and the clamp. The rod part 18 of the clamp has threads, and can cooperate with the auxiliary clamps 8 and 19 on the blade mounting plate and the end surface of the tenon to realize position adjustment.

Fig. 6 is a schematic diagram of the relationship between the workpiece position error and the positioning point error. In the figure, XYZ is a fixed coordinate system, C _i is the positioning point, R _i is the coordinate of the contact point between the positioning point and the workpiece, and n _i is the normal vector of the contact point. δ _q is the position error of any point on the workpiece, and δ _yi is the positioning point error caused by the position error of the workpiece.

Detailed ways

Selection scheme of anchor points

In order to ensure the stable positioning of the mortise 14 during processing, the positioning reference and the design reference should coincide as much as possible, first select the blade design reference point on the blade mounting plate 15 as a positioning point d5, and then according to the three-dimensional mathematical model of the blade surface 16, in Select another five anchor points d1, d2, d3, d4, d6 on its surface. Firstly, the precision-constrained mathematical model of the positioning point is established based on the position error of the positioning point caused by the disturbance of the workpiece position; then, the bi-cubic B-spline is used to fit the position coordinates of the feature points obtained from the design on the blade profile, and the feature points including the normal vector are calculated The space vector of the positioning point is obtained to obtain the point set space of the positioning point to be selected; secondly, assuming that the error of the positioning point obeys the normal distribution, the optimal criterion for the best position accuracy of the workpiece is obtained according to the statistical theory; again, based on the shape-closed theory of the positioning of the workpiece, the positioning of the fixture is determined Finally, in the point set space of the feature points of the blade profile, select five positioning points with the highest precision that meet the above optimization criteria and satisfy the shape closure constraint conditions. The specific selection method is as follows:

The first step: establish the mathematical model of the precision constraint of the positioning point.

The schematic diagram of the relationship between the workpiece position error and the positioning point error is shown in Figure 7, where the normal vector of the positioning point and the contact point of the workpiece is n _i , and the coordinate of the contact point is R _i . Then the position error of the positioning point caused by the position disturbance δq={δb, δθ} of any point of the workpiece is ${\mathrm{\δy}}_i=h_i^T\mathrm{\δq},$ in $h_i^T=-\left\{{\mathrm{no}}_i^T{(R_i\×{\mathrm{no}}_i)}^T\right\}.$

Therefore, the accuracy constraint of a fixture with l positioning points, that is, the position error of the positioning points can be expressed as: δy=G ^T δq, where: δy={δy ₁ , δy ₂ ,...,δy _l }, G= [h ₁ , h ₂ , . . . , h _l ].

Step 2: Obtain the point set space of the selected anchor point.

The position coordinates of a large number of feature points on the blade surface are provided in the blade model, but the normal vectors of the feature points are not provided. In order to obtain the feature point vector g _i =[R _i n _i ] including the feature point normal vector, use the bicubic B-spline to fit the position coordinates of the feature point, and obtain the blade profile control node expressed by the B-spline; According to the obtained B-spline surface control nodes, the normal vectors of the blade surface feature points are calculated. Thus, the point set space of the selected anchor point is obtained.

Step 3: Determine the best optimization criterion based on location accuracy.

It is assumed that the error of each positioning point follows a normal distribution: δy≈N(0, V _y ), where V _y =diag{δ ₁ , δ ₂ ... δ _l }. According to statistical theory, the position variance matrix of the anchor point $V=\mathrm{Var}\left(\mathrm{\δq}\right)={\left({\mathrm{GV}}_{\mathrm{the\; y}}^{-1}{G}^T\right)}^{-1}.$ Assuming A=V ^-1 , the condition for making the position accuracy of the workpiece the best is max(det A).

For the actual situation, since the material properties of each positioning element are the same, the δy _i of different positioning points obey the same distribution δy _i ≈ N(0, V _y ), then $V={\left({\mathrm{GV}}_{\mathrm{the\; y}}^{-1}{G}^T\right)}^{-1}={\left(\mathrm{G\δ}{G}^T\right)}^{-1},$ A=V ^-1 =GδG ^T =δGG ^T , so the best optimization criterion for the workpiece position accuracy is: max(det A)=max(det(GG ^T )).

Step 4: Determine the optimization constraints based on shape closure.

For a given fixture positioning point distribution G=[h ₁ , h ₂ ,...,h _l ], if any external force acts on the workpiece, the position of the fixture positioning point does not change, and there is a force acting on each positioning point normal positive force, then the distribution of anchor points in this state G=[h ₁ , h ₂ ,..., h _l ] satisfies the shape closure. If the anchor point of the fixture satisfies the shape closure condition. Then select a position vector h _c arbitrarily in the anchor point position matrix G, and apply any external force along its normal direction. For all h _i , α _i =-h _i ^T A ^-1 h _c should satisfy a _i >0.

Step 5: Optimize the five anchor points on the blade profile.

In the point set space g _i =[R _i n _i ](1≤i≤N) of the feature points of the blade profile, with max(det A) as the optimization criterion, under the constraint condition α _i >0, select of the five positioning points. The specific optimization process is as follows:

Step a: Initialize. Calculate the position vector h ₀ of the determined positioning point on the blade mounting plate, and calculate the direction vectors of all N points in the point set g _i =[R _i n _i ](1≤i≤N), and initialize G ₀ ; After obtaining G ₀ = {h ₀ h ₁ ... h _N } (wherein h ₀ is the determined anchor point), calculate the corresponding A ₀ and A ₀ ^-1 ; then choose arbitrarily in the anchor point position matrix G ₀ A position vector h _c , any external force is applied along its normal direction, for a given h _i (1≤i≤N), calculate α _i =-h _i ^T A ₀ ^-1 h _c , and let k=N;

Step b: If there are anchor points that do not satisfy shape closure, delete the point j that makes p _j = h _j ^T A _m ^-1 h _j (m=Nk) the smallest among these points; if all anchor points satisfy the Closed conditions, then directly delete the anchor point j that makes p _j =h _j ^T A _m ^-1 h _j (m=Nk) the smallest, and make k=k-1;

Step c: Reorder the point set, the new point set becomes g _i ＝[R _i n _i ](1≤i≤k), update G _m ＝{h ₀ h ₁ ...h _k }, A _m , A _m ^-1 and α _i =-h _i ^T A _m ^-1 h _c (m=Nk), and then repeat Step b. Repeat this until k=5.

Choice of clamping point

Arrange the six positioning pins 1, 2, 3, 4, 5, 6 on the fixture according to the determined six positioning points d1, d2, d3, d4, d5, d6, so that the six round head positioning pins are respectively located at The normal direction of the blade positioning points d1, d2, d3, d4, d5, and d6 ensures that after the blade is placed and in contact with the positioning pin, the positioning pin is perpendicular to the tangent plane of the blade positioning point. In the selection of the clamping point, try to avoid the weak links, select the clamping pin 7 at the top of the relatively flat blade, and select the corresponding lateral auxiliary clamps 20, 21 at the places with larger rigidity, larger area, The top of the tenon 14 with a relatively regular shape (Fig. Figure 4). Minimize the force and deformation of the hollow blade body.

Design scheme of blade tenon processing fixture

The designed tenon processing fixture for turbine blades is mainly composed of fixture main body 10, six fixed and non-adjustable positioning pins 1, 2, 3, 4, 5, 6, top clamping pin 7, blade mounting plate auxiliary fixture 8, tenon The end surface is composed of an auxiliary clamp 19 and an auxiliary clamp whose position can be adaptively adjusted. The auxiliary clips include blade mounting plate auxiliary clips 9 , 11 , 12 , 13 and blade tenon end auxiliary clips 20 , 21 . The auxiliary clamp 19 attached to the end surface of the tenon and the main body 10 of the clamp adopt a split structure to facilitate the installation of blades; the auxiliary clamp 8 of the mounting plate and the main body 10 of the clamp adopt an integrated structure to improve the rigidity of the upper and lower clamping. The top clamping pin 7 adopts a fine-toothed screw structure that can be moved precisely to ensure accurate clamping of the top of the blade. Auxiliary clamps 9, 11, 12, 13, 20, 21 adopt self-adaptive contact design (Fig. 5). The head 17 and rod 18 are fitted with plane and spherical surfaces, allowing a certain degree of contact surface between the workpiece and the auxiliary clamps. The angle error; the auxiliary clamp rod 18 is a screw structure, which can realize the position adjustment of the auxiliary clamp.

Positioning and clamping process of blade tenon processing jig

As shown in Figure 3, before positioning and clamping, the tenon end surface auxiliary clamp 19 is pushed away from the clamp body 10 as a whole, and the blade top clamping pin 7, the tenon top auxiliary clamps 20, 21 and the blade mounting plate auxiliary clamp 9 , 11, 12, and 13 are adjusted to the furthest position respectively. With the blade profile 16 facing inward and the tenon 14 end facing outward, slowly push the left end of the clamp into the fixture main body 10 along the horizontal direction, and make the blade mounting plate 15 and the blade profile 16 respectively align with the six positioning pins 1- 6 contacts to achieve accurate positioning. First, adjust the clamping pin 7 at the top of the blade to be in close contact with the blade, then move the tenon end surface auxiliary clamp 19 close to the clamp body 10, and adjust the screw-in screws of the tenon end auxiliary clamps 20, 21 to achieve left and right clamping of the blade. After the left and right sides of the blade are clamped, respectively adjust the screw-in screws of the auxiliary clamps 9, 11, 12, and 13 of the blade mounting plate to realize the stable clamping and fastening of the blade up and down.

Claims (8)

1, a kind of turbine hollow blade tenon processing method for positioning and clamping is characterized in that, comprises the selection of blade profile anchor point and carries out the auxiliary clamping of the clamping of blade profile location and blade tenon top and blade installing plate according to selected site; Wherein, the selection of blade profile anchor point, at first a side selects one the 5th anchor point as datum mark on blade installing plate blade, utilizes given blade profile design data then, sets up the accuracy constraint Mathematical Modeling of blade anchor point; Obtain choosing the point set space of anchor point, determine the anchor point selection optimization criterion that the position-based precision is best then; Shape sealing according to anchor point requires to determine to optimize constraints again; Optimize at last and choose and five anchor points of definite blade profile: first to fourth top anchor point and the 6th following anchor point; According to first to the 6th alignment pin on the next corresponding arrangement jig main body of determined first to the 6th anchor point, make six alignment pin round ends lay respectively at the normal direction of blade first to the 6th anchor point, guarantee that blade is put into and with after alignment pin contacts, alignment pin is perpendicular to blade anchor point section; Holding pin is set on the jig main body is positioned at blade tip, and about the blade tenon end face adopts the tenon end face auxiliary clamp that separates with jig main body with blade, clamp away from blade tenon; Adopt the installing plate auxiliary clamp that is connected as a single entity with jig main body to realize that the blade above-below direction clamps in both sides up and down at the blade installing plate.

2, turbine hollow blade tenon processing method for positioning and clamping as claimed in claim 1 is characterized in that following concrete steps are adopted in the selection of described blade profile anchor point:

The first step, according to location of workpiece error and anchor point error relation, promptly the normal vector of anchor point and workpiece contact point is n _i, the contact point coordinate is R _i, then by the position disturbance δ of workpiece arbitrfary point _qThe site error of=the anchor point that { δ b, δ θ } brings is ${\mathrm{\δy}}_i=h_i^T\mathrm{\δq},$ Wherein $h_i^T=-\left\{n_i^T{(R_i\×n_i)}^T\right\}$ Be the locating point position vector; Therefore, have the accuracy constraint of the anchor clamps of l anchor point, promptly the site error of anchor point can be expressed as: δ y=G ^Tδ q, wherein: δ y={ δ y ₁, δ y ₂..., δ y _l, G=[h ₁, h ₂..., h _l] be the locating point position matrix, the corresponding anchor clamps anchor point of each locating point position matrix G distributes;

Second goes on foot, and the position coordinates of blade surface characteristic point is provided in the leaf model, utilizes the cubic B batten that the position coordinates of characteristic point is carried out match, obtains the blade profile control node of B batten statement; B-spline surface control node according to obtaining calculates the normal vector of blade surface characteristic point, thereby obtains choosing the point set space g of anchor point _i=[R _in _i] (1≤i≤N);

The 3rd step: the error Normal Distribution of supposing each anchor point: δ y ≈ N (0, V _y), V wherein _y=diag{ δ ₁, δ ₂... δ _l, the position variance matrix of anchor point is $V=\mathrm{Var}\left(\mathrm{\δq}\right)={\left({\mathrm{GV}}_y^{-1}{G}^T\right)}^{-1},$ Make A=V ^-1, the best condition of positional precision that then makes workpiece is max (det A); Because the material behavior of each setting element is identical, so the δ y of different anchor points _iObey identical distribution δ y _i≈ N (0, V _y), then have

$V={\left({\mathrm{GV}}_y^{-1}{G}^T\right)}^{-1}={\left({\mathrm{G\δG}}^T\right)}^{-1}$ ，A＝V ^-1＝GδG ^T＝δGG ^T，

Therefore the best optimization criterion of location of workpiece precision is: max (det A)=max (det (GG ^T));

The 4th step: for given anchor clamps locating point position matrix G=[h ₁, h ₂..., h _l], when acting on any external force on the workpiece, the anchor clamps locating point position does not change, and effect has the positive power of normal direction, the locating point position matrix G=[h under the then this state on each anchor point ₁, h ₂..., h _l] just satisfy the shape sealing, if the anchor clamps anchor point satisfies the shape sealing condition, then in locating point position matrix G, select a position vector h arbitrarily _c, apply any external force along its normal direction, for all h _i, a _i=-h _i ^τA ^-1h _cShould satisfy a _i0;

The 5th step: at the point set space of blade profile characteristic point g _i=[R _in _i] (among 1≤i≤N), serve as to optimize criterion with max (det A), at constraints a _iOptimize 0 time and to choose five anchor points with full accuracy.

3, turbine hollow blade tenon processing method for positioning and clamping as claimed in claim 2 is characterized in that the concrete steps that five anchor points with full accuracy are chosen in described optimization are as follows:

A. initialization, the position vector h of anchor point on the blade installing plate that calculating has been determined ₀, and calculate point set g _i=[R _in _i] (direction vectors of all N points among 1≤i≤N) are to locating point position matrix G ₀Initialization; Obtain G ₀={ h ₀h ₁... h _N, h wherein ₀Be the anchor point of having determined, calculate corresponding A ₀And A ₀ ^-1Then at locating point position matrix G ₀In select a position vector h arbitrarily _c, apply any external force along its normal direction, for given h _i(1≤i≤N), calculate a _i=-h _i ^TA _o ^-1h _cAnd make k=N;

If b. there is the anchor point do not satisfy the shape sealing, then deletion makes p in these points _j=h _j ^TA _m ^-1h _j(m=N-k) Zui Xiao some j; If all anchor points all satisfy the shape sealing condition, then directly deletion makes p _j=h _j ^TA _m ^-1h _j(m=N-k) Zui Xiao anchor point j, and make k=k-1;

C. with the point set rearrangement, new point set becomes g _i=[R _in _i] (1≤i≤k), upgrade G _m={ h ₀h ₁... h _k, A _m, A _m ^-1And a _i=-h _i ^TA _m ^-1h _c(m=N-k), repeating step b again, so repeatedly, up to k=5.

4, turbine hollow blade tenon processing method for positioning and clamping as claimed in claim 1, it is characterized in that, the tenon end face auxiliary clamp and the installing plate auxiliary clamp of described blade be equipped with can regulate and self adaptation contact the design auxiliary folder, should comprise head and bar portion by auxiliary folder, the last plane of head contacts with workpiece, and inner plane contacts with the sphere on bar portion top.

5, turbine hollow blade tenon as claimed in claim 4 processing method for positioning and clamping is characterized in that, described bar portion is provided with screw thread, can cooperate realization position adjustment with the tenon end face and the attached anchor clamps that help of installing plate of blade.

6, a kind of anchor clamps of realizing claim 1 turbine hollow blade tenon processing method for positioning and clamping comprise jig main body, it is characterized in that, are connected with the installing plate auxiliary clamp of realizing that the blade above-below direction clamps on the jig main body; Jig main body is provided with first to the 6th alignment pin of respective vanes first to the 6th anchor point, make six alignment pin round ends lay respectively at the normal direction of blade first to the 6th anchor point, guarantee that blade is put into and with after alignment pin contacts, alignment pin is perpendicular to blade anchor point section; Also be provided with holding pin on the jig main body, this holding pin and a tenon end face auxiliary clamp that separates with jig main body clamp about with blade.

7, a kind of anchor clamps of realizing claim 1 turbine hollow blade tenon processing method for positioning and clamping as claimed in claim 6, it is characterized in that, the tenon end face auxiliary clamp and the installing plate auxiliary clamp of described blade be equipped with can regulate and self adaptation contact the design auxiliary folder, should comprise head and bar portion by auxiliary folder, the last plane of head contacts with workpiece, and inner plane contacts with the sphere on bar portion top.

8, a kind of anchor clamps of realizing claim 1 turbine hollow blade tenon processing method for positioning and clamping as claimed in claim 7 is characterized in that, described bar portion is provided with screw thread, can cooperate realization position adjustment with the tenon end face and the attached anchor clamps that help of installing plate of blade.

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