Optimization design method for air engine blade body burr bridge

Abstract

The application discloses an aero-engine blade airfoil burr bridge optimization design method, comprising the following steps: setting an airfoil allowance on the basis of a blade airfoil design profile line, determining a front edge position, taking the front edge burr bridge as an example, determining point A as a front edge arc center point, auxiliary circle B and auxiliary circle C as inscribed circles of a blade basin and a blade back curve, the center point D of auxiliary circle D being on straight line AE, line segments E1E2 and D1D2 being perpendicular to straight line AE, straight line AE being a tangent line of an arc of the arc center point A and the center points of auxiliary circle B and auxiliary circle C, and the burr bridge being obtained by drawing arcs through points C1, D1, E1 and C2, D2 and E2 respectively, and the burr bridge height can be adjusted by adjusting the diameters of auxiliary circle D and auxiliary circle E, so that the burr resistance can be adjusted. The application can effectively reduce problems such as burr burst and airfoil crack in the production process, reduce labor intensity, and improve work efficiency.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine blade mold technology, specifically relating to a design and optimization method for aero-engine blade burr bridges. Background Technology

[0002] Open die forging is an important forming method for aero-engine blades. To facilitate the filling of the forging and accommodate excess metal, a burr bridge is designed around the parting surface of the die. The blade blade burr bridge design is a design method that adds allowance to the inlet and outlet edges of the blade forging profile to form burrs. It is a necessary step in blade die design and an important process from forging drawings to matching die design and forming.

[0003] Currently, a common type of burr bridge structure in the industry is as follows: Figure 1 As shown, this burr bridge is a rectangular cross-section burr bridge. The key dimensions of the burr bridge are the bridge height h and the width b. When h increases, the resistance to the metal flow towards the burr decreases, which is not conducive to filling the die cavity, but the stress in the die cavity also decreases, and vice versa; when the width b increases, the resistance increases, and vice versa.

[0004] During blade production, some blade models exhibited burr cracking and blade body cracks. While measures were taken to remove and repair the burr bridges, the effect was minimal, resulting in a low yield rate and increased production costs for these blade models. Therefore, the applicant conducted research on optimizing the burr bridge design. Summary of the Invention

[0005] This invention aims to provide an optimized design method for burr bridges on aero-engine blades, which can more accurately realize the blade processing design from forging to mold, effectively reduce problems such as burr cracking and blade cracks during production, reduce labor intensity, and improve work efficiency.

[0006] The technical solution of the present invention is as follows:

[0007] An optimized design method for blade blade burr bridges, including the design steps for blade leading-edge burr bridges.

[0008] Step 1: Select the center point A of the arc at the leading edge of the leaf. Draw auxiliary circles B and C between the arc corresponding to the center point A and the leaf base curve and leaf back curve connected to the arc. Auxiliary circle B is located between the arc corresponding to the center point A and auxiliary circle C. Auxiliary circle B is tangent to the leaf base curve and leaf back curve. Auxiliary circle C is tangent to the leaf base curve and leaf back curve at points C1 and C2.

[0009] Step 2: Draw an arc through the center point A of the arc, the center point B of the auxiliary circle B, and the center point C of the auxiliary circle C. Draw a line segment through the center point A of the arc, and make the line segment tangent to the arc through the center point A, the center point B, and the center point C. The endpoint of the line segment is point D. Extend the line segment to point E in the direction from the center point A of the arc to point D.

[0010] Step 3: Draw auxiliary circles D and E with points D and E as centers respectively, where the diameter of auxiliary circle D is equal to the diameter of auxiliary circle B;

[0011] Step 4: Draw line segments D1D2 and E1E2 through points D and E respectively, with line segments D1D2 and E1E2 perpendicular to the line AD containing the center point A and point D of the arc. Line segment D1D2 intersects the auxiliary circle D at points D1 and D2, and line segment E1E2 intersects the auxiliary circle E at points E1 and E2.

[0012] Step 5: Take point Q1 on the leading edge of the leaf-bowl curve in Step 1, and point Q2 on the leading edge of the leaf-back curve in Step 1. Use points Q1, C1, D1 and E1 as control points of the spline curve to draw the bridge curve in the bowl direction, and use points Q2, C2, D2 and E2 as control points of the spline curve to draw the bridge curve in the back direction.

[0013] Furthermore, the optimization design method for blade burr bridges in aero-engines also includes design steps for trailing edge burr bridges.

[0014] Step 1: Select the center point A' of the arc at the trailing edge of the leaf. Draw auxiliary circles B' and C' between the arc corresponding to the center point A' and the leaf base curve and leaf back curve connected to the arc. Auxiliary circle B' is located between the arc corresponding to the center point A' and auxiliary circle C'. Auxiliary circle B' is tangent to the leaf base curve and leaf back curve. Auxiliary circle C' is tangent to the leaf base curve and leaf back curve at points C'1 and C'2.

[0015] Step 2: Draw an arc through the center point A' of the arc, the center point B' of the auxiliary circle B', and the center point C' of the auxiliary circle C'. Draw a line segment through the center point A' of the arc, and make the line segment tangent to the arc through the center point A', the center point B', and the center point C'. The endpoint of the line segment is point D'. Extend the line segment to point E' in the direction from the center point A' of the arc to point D'.

[0016] Step 3: Draw auxiliary circles D' and E' with points D' and E' as centers respectively, where the diameter of auxiliary circle D' is equal to the diameter of auxiliary circle B'.

[0017] Step 4: Draw line segments D'1D'2 and E'1E'2 through points D' and E' respectively, with both line segments D'1D'2 and E'1E'2 perpendicular to the straight line A'D' containing the center point A' and point D' of the arc. Line segment D'1D'2 intersects the auxiliary circle D' at points D'1 and D'2, and line segment E'1E'2 intersects the auxiliary circle E' at points E'1 and E'2.

[0018] Step 5: Take point Q'1 on the trailing edge of the leaf-bowl curve in Step 1, and point Q'2 on the trailing edge of the leaf-back curve in Step 1. Use points Q'1, C'1, D'1, and E'1 as control points of the spline curve to draw the bridge curve in the bowl direction, and use points Q'2, C'2, D'2, and E'2 as control points of the spline curve to draw the bridge curve in the back direction.

[0019] As an alternative, in order to adjust the magnitude of the burr drag, based on the aforementioned optimization design method for the burr bridge of the aero-engine blade body, the diameters of the auxiliary circle D and auxiliary circle E in step 3, or the diameters of the auxiliary circle D' and auxiliary circle E', are adjusted to adjust the height of the burr bridge and change the magnitude of the burr drag.

[0020] Compared with the prior art, this invention, based on the blade profile design, sets a blade margin, determines the leading and trailing edge positions, and determines point A (A') as the center point of the leading (trailing) edge arc. Auxiliary circles B (B') and C (C') are the inscribed circles of the blade base and blade back curves. The center point D (D') of auxiliary circle D (D') lies on the straight line AE (A'E'). Line segments E1E2 (E'1E'2) and D1D2 (D'1D'2) are perpendicular to the straight line AE (A'E'). The straight line AE (A'E') is the tangent to the arc drawn from the center point A (A') of the arc and the center points of auxiliary circles B (B') and C (C'). By drawing arcs through points C1 (C'1), D1 (D'1), E1 (E'1) and C2 (C'2), D2 (D'2), E2 (E'2) respectively, the burr bridge is obtained. In addition, the height of the burr bridge can be adjusted by adjusting the diameter of auxiliary circles D (D') and E (E'), thereby adjusting the burr resistance.

[0021] The burr bridge optimization design method of this invention ensures that the metal flow direction is parallel to the burr bridge, thus avoiding stress concentration at the burr edge and preventing it from becoming a crack source; the burr resistance is small, thus avoiding excessive internal stress in the forging and causing cracks, and specifically solves the external causes of burr cracking and blade cracking in existing burr bridges.

[0022] On the other hand, the burr bridge structure of the present invention has a thicker burr edge at the initial burr formation compared to existing burr bridges, resulting in higher strength and less susceptibility to cracking.

[0023] This invention was applied to the mold design of various blades. Blades produced using the improved mold with a burr bridge exhibited no burr cracking and no blade cracks, effectively improving the yield rate and reducing production costs. Before and after comparison photos of the produced products are shown in the instruction manual. Figure 2 As shown. Attached Figure Description

[0024] Figure 1 To improve the burr bridge of the forging die for the front blade;

[0025] Figure 2 The images show the forgings before and after the improvement of the burr bridge; the left image is before the improvement, and the right image is after the improvement.

[0026] Figure 3 This is a schematic diagram of the optimized design method for rough-edged bridges according to the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0028] like Figure 3 As shown, the design process of the mold bridge is illustrated by taking the leading edge of the blade as an example. Point A is the center of the leading edge arc. The auxiliary circles B, C, D, and E are all dimensioned with the center point A of the arc as the reference.

[0029] a. Construct auxiliary circles B and C: First, draw two circles with centers at points B and C respectively. Constrain the circles to be tangent to the leaf-bowl curve and the leaf-back curve. Then constrain the distance between the center line segment AB to 0.3 and the distance between the center line segment AC to 0.7. This will give you the tangent points C1 and C2 between the auxiliary circle C and the leaf-back curve.

[0030] b. Draw a straight line extending in the direction of the arc: Draw an arc through the three points A, B and C of the arc, and then draw a straight line through the center point A of the arc. Constrain the straight line to be tangent to the arc. The endpoint of the straight line extending outward is point D. Constrain the distance of line segment AD to be 2.5. Line segment AD extends outward.

[0031] c. Draw auxiliary circles D and E: Draw auxiliary circle D at the endpoint of line segment AD. The diameter of auxiliary circle D is equal to the diameter of auxiliary circle B. Continue to extend line segment AD to point E. Constrain the distance of line segment AE to 6. Draw auxiliary circle E at point E. Constrain the diameter of auxiliary circle E to 2.5.

[0032] d. Construct control points for the bridge curve: Draw line segments D1D2 and E1E2 through points D and E respectively, making line segments D1D2 and E1E2 perpendicular to line segment AD. Constrain points D1 and D2 on auxiliary circle D, and constrain points E1 and E2 on auxiliary circle E, thus obtaining control points D1, D2, E1, and E2. Based on the front and rear edge positions of the forging drawing, take points Q1 and Q2 on the blade basin curve and blade back curve.

[0033] e. Construct the bridge section curves: Using points Q1, C1, D1, and E1 as control points of the spline curve, construct the bridge section curves in the basin direction. Similarly, using points Q2, C2, D2, and E2 as control points of the spline curve, construct the bridge section curves in the opposite direction.

[0034] The design of the trailing edge burr bridge on the blade is carried out in the same way as above, and the design of the burr bridge on the blade body of the aero-engine can be completed.

[0035] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. An optimization design method for burr bridges on aero-engine blades, characterized by: This includes the design steps for blade leading edge burr bridges. Step 1: Select the center point A of the arc at the leading edge of the leaf. Draw auxiliary circles B and C between the arc corresponding to the center point A and the leaf base curve and leaf back curve connected by the arc corresponding to the center point A. Auxiliary circle B is located between the arc corresponding to the center point A and auxiliary circle C. Auxiliary circle B is tangent to the leaf base curve and leaf back curve. Auxiliary circle C is tangent to the leaf base curve and leaf back curve at points C1 and C2. Step 2: Draw an arc through the center point A of the arc, the center point B of the auxiliary circle B, and the center point C of the auxiliary circle C. Draw a line segment through the center point A of the arc that is tangent to the arc through the center point A, the center point B, and the center point C. The endpoint of the line segment through the center point A of the arc is point D. Extend the line segment through the center point A of the arc to point E in the direction from the center point A of the arc to point D. Step 3: Draw auxiliary circles D and E with points D and E as centers respectively, where the diameter of auxiliary circle D is equal to the diameter of auxiliary circle B; Step 4: Draw line segments D1D2 and E1E2 through points D and E respectively, with line segments D1D2 and E1E2 perpendicular to the line AD containing the center point A and point D of the arc. Line segment D1D2 intersects the auxiliary circle D at points D1 and D2, and line segment E1E2 intersects the auxiliary circle E at points E1 and E2. Step 5: Take point Q1 on the leading edge of the leaf-bowl curve in Step 1, and point Q2 on the leading edge of the leaf-back curve in Step 1. Use points Q1, C1, D1 and E1 as control points of the spline curve to draw the bridge curve in the bowl direction, and use points Q2, C2, D2 and E2 as control points of the spline curve to draw the bridge curve in the back direction.

2. The method for optimizing the design of burr bridges on aero-engine blades according to claim 1, characterized in that: It also includes the design steps for blade trailing edge burrs. Step 1': Select the center point A' of the arc at the trailing edge of the leaf. Draw auxiliary circles B' and C' between the arc corresponding to the center point A' and the leaf base curve and leaf back curve connected by the arc corresponding to the center point A'. Auxiliary circle B' is located between the arc corresponding to the center point A' and auxiliary circle C'. Auxiliary circle B' is tangent to the leaf base curve and leaf back curve. Auxiliary circle C' is tangent to the leaf base curve and leaf back curve at points C'1 and C'2. Step 2': Draw an arc through the center point A' of the arc, the center point B' of the auxiliary circle B', and the center point C' of the auxiliary circle C'. Draw a line segment through the center point A' of the arc that is tangent to the arc through the center point A', the center point B', and the center point C'. The endpoint of the line segment through the center point A' is point D'. Extend the line segment through the center point A' of the arc to point E' in the direction from the center point A' of the arc to point D'. Step 3': Draw auxiliary circles D' and E' with points D' and E' as centers respectively, where the diameter of auxiliary circle D' is equal to the diameter of auxiliary circle B'. Step 4': Draw line segments D'1D'2 and E'1E'2 through points D' and E' respectively, with both line segments D'1D'2 and E'1E'2 perpendicular to the straight line A'D' containing the center point A' and point D' of the arc. Line segment D'1D'2 intersects the auxiliary circle D' at points D'1 and D'2, and line segment E'1E'2 intersects the auxiliary circle E' at points E'1 and E'2. Step 5': Take point Q'1 on the trailing edge of the leaf-bowl curve in Step 1', and point Q'2 on the trailing edge of the leaf-back curve in Step 1'. Use points Q'1, C'1, D'1, and E'1 as control points of the spline curve to draw the bridge curve in the basin direction, and use points Q'2, C'2, D'2, and E'2 as control points of the spline curve to draw the bridge curve in the back direction.

3. The method for optimizing the design of burr bridges on aero-engine blades according to claim 1 or 2, characterized in that: Adjust the diameters of auxiliary circles D and E in step 3, or the diameters of auxiliary circles D' and E' in step 3', to adjust the height of the rough edge bridge.

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