Precision machining method for additive airfoil

Abstract

The invention provides a precision machining method for an additive airfoil, which comprises the following steps of: selecting a tool material meeting clamping and supporting requirements according to the hardness, rigidity and stress during machining of the additive airfoil; according to the structure of the additive airfoil, the basic forms and clamping modes of the two tools are designed; a corresponding cambered surface of the tool, a positioning hole and a threaded hole for clamping are machined; the additive airfoil is clamped on a first tool, the first tool is clamped on a three-axis machine tool and positioned through a positioning hole, and the front face characteristics of the connector are machined according to the final product size; the first tool is clamped on a four-axis machine tool, positioning is conducted through the positioning holes, and the connector and the side face characteristics of the fixed wing face are machined; and the additional material airfoil is detached from the first tool, the back face of the additional material airfoil is installed on the second tool, the second tool is clamped on the three-axis machine tool and located through the locating hole, and the back face characteristics of the connector are machined according to the final product size.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing and is a rapid positioning fixture for an additive wing surface and a precision processing method. Background Art

[0002] At present, in the field of aerospace, the required metal parts are first formed by additive manufacturing, and then the products are precision machined. This manufacturing method is becoming more and more widely used. Additive manufacturing can directly form complex parts with irregular shapes, with small workpiece blank allowances, reducing the time for subsequent processing. Most of the non-installation surfaces of the workpiece blank after additive manufacturing are not processed, and the positioning reference cannot be accurately given during processing. In addition, the processing of various complex surfaces cannot be completed in one clamping. During multiple clamping processes, the reference transfer will affect the size and shape and position accuracy of the workpiece, which makes the processing of such products more difficult. Summary of the invention

[0003] The technical problem solved by the present invention is to overcome the problem of low dimensional accuracy during mechanical processing of additive airfoils in the prior art and provide a precision processing method for additive airfoils.

[0004] The technical solution of the present invention is: a precision machining method of an additive airfoil, wherein the additive airfoil comprises a fixed airfoil and a joint; comprising:

[0005] According to the hardness, rigidity and stress of the additively manufactured wing surface, select the tooling material that meets the clamping and support requirements;

[0006] According to the structure of the additive wing surface, the basic forms and clamping methods of two toolings are designed, wherein the first tooling is used to process the front side of the additive wing surface and can be clamped on a three-axis or four-axis machine tool, and the second tooling is used to process the back side of the additive wing surface and can be clamped on a three-axis machine tool;

[0007] According to the size, camber shape and clamping requirements of the additive wing surface, the corresponding camber, positioning holes and threaded holes for clamping of the tooling are processed; the tooling after processing is tightly matched with the additive wing surface, and the rest of the area on the additive wing surface except the area to be processed is in contact with the tooling, and there is no processing obstructed surface;

[0008] The additive airfoil is clamped on the first fixture, which is clamped on the three-axis machine tool and positioned using the positioning holes, and the front features of the joint are machined according to the final product size;

[0009] Clamp the first tooling on a four-axis machine tool and position it using the positioning holes on the machine tool to process the side features of the joint and the fixed wing surface;

[0010] The additive airfoil is removed from the first fixture and its back is mounted on the second fixture. The second fixture is clamped on a three-axis machine tool and positioned using positioning holes to machine the back features of the joint according to the final product size.

[0011] Preferably, the material hardness of the tooling is not less than the hardness of the additive airfoil, and its rigidity satisfies the need to support the additive airfoil without deformation during processing.

[0012] Preferably, the first tooling comprises a base plate and two types of pressure plates; the base plate comprises three parts, the middle part is used for conformal installation with the additive wing surface, the upper and lower parts are used to fix the first type of pressure plate, the middle part of the first type of pressure plate is an arc surface conforming to the shape of the additive wing surface, and the two end parts are used for fixed installation with the upper and lower parts of the base plate; one end of the second type of pressure plate is used for fixed installation with the upper part of the base plate, and the other end presses the joint of the additive wing surface through a clamping force.

[0013] Preferably, the width of the middle portion of the bottom plate is smaller than the width of the fixed wing surface, and the width difference between the two on one side is 5-10 mm.

[0014] Preferably, the second tooling includes a base plate and a first type of pressure plate; the base plate includes three parts, the middle part is installed in conformity with the front face of the additive wing surface, a cylindrical protrusion is provided on it for cooperating with the circular hole on the joint, and a positioning pin hole is provided for corresponding to the position of the processed pin hole on the joint; the upper and lower parts are used to fix the first type of pressure plate, the middle part of the first type of pressure plate is an arc surface that conforms to the shape of the additive wing surface, and the two end parts are used to be fixedly installed with the upper and lower parts of the base plate.

[0015] Preferably, the gap between the cylindrical protrusion and the corresponding circular hole on the joint is 1-2 mm.

[0016] Preferably, there are a plurality of first type pressure plates, which are arranged at locations where reinforcing ribs are arranged inside the fixed wing surface.

[0017] Preferably, the machining allowance of the to-be-machined portion of the additively-made wing surface is 2-3 mm.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] The implementation of the present invention is aimed at the additive wing surface, whose surface shape to be processed is irregular and it is difficult to accurately obtain the positioning point, and some complex surfaces with small margins cannot be processed in one go, which affects the dimensional accuracy of some workpieces during repeated clamping. The implementation of the present invention can effectively solve the problem that the positioning accuracy of the machining coordinate origin is low and the symmetry of the two side walls of the wing surface is poor due to the arc surface of the formed wing surface, and each process can be quickly positioned and clamped, and can form an assembly line operation during mass production to improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of the additive airfoil provided for the implementation of the present invention;

[0021] Figure 2 A schematic diagram of the structure of a tool 1 for clamping an airfoil on three axes provided for the implementation of the present invention;

[0022] Figure 3 A schematic diagram of the structure of a tool 1 for clamping a wing surface on four axes provided for the implementation of the present invention;

[0023] Figure 4 A schematic diagram of the structure of the tooling 2 for clamping the flipped rear wing surface on three axes provided for the implementation of the present invention;

[0024] Figure 5 A schematic diagram of the structure of a tool 1 used on three axes and four axes for implementing the present invention;

[0025] Figure 6 A schematic diagram of the structure of the tooling 2 used on the reverse rear three axes provided for the implementation of the present invention; DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments.

[0027] like Figure 1 As shown, the additive wing surface obtained by 3D printing includes a fixed wing surface and a joint; the fixed wing surface is used as the fitting surface of the tooling, and the processing parts of the present invention are various parts of the joint and Figure 2 End surface features on the right side of the fixed wing.

[0028] The present invention provides a flow chart of the steps of a precision machining method for an additive airfoil, such as Figure 1 As shown, the precision machining method of the additive airfoil may specifically include the following steps:

[0029] Step 101: Select tooling materials that meet the clamping and support requirements based on the hardness and rigidity of the formed airfoil and the magnitude of the force applied during processing.

[0030] When selecting the material for tooling and determining the thickness of the tooling, it is necessary to consider the stress conditions of the tooling during the actual processing and the stress deformation of the wing surface when it is fastened to the tooling.

[0031] The hardness of the tooling material is not less than that of the wing surface, and its rigidity meets the need to support the wing surface without deformation during processing. When the additive wing surface material is aluminum silicon + magnesium alloy, the tooling material is 45# steel.

[0032] After determining the appropriate material and tooling size, proceed to step 102

[0033] Step 102: According to the structure and size of the additive airfoil, a basic form (adaptive form) of the tooling and the clamping method required in the corresponding machining center are preset.

[0034] The designed tooling shape can provide good support for the wing surface and reduce deformation and vibration caused by the processing process. The present invention designs two toolings. The first tooling is used to process the front of the additive wing surface and can be clamped on a three-axis or four-axis machine tool (such as Figure 2 , 3 As shown), the second tooling is used to process the back side of the additive wing surface and can be clamped on a three-axis machine tool. The clamping methods of the two toolings should be suitable for assembly line processing.

[0035] After the basic form of the tooling and the clamping method required in the corresponding machining center are preset according to the structure and size of the formed airfoil, step 103 is executed.

[0036] Step 103: According to the size, precise camber shape and clamping requirements of the formed wing surface, the corresponding camber and shape of the tooling are machined, and threaded holes for clamping the workpiece are machined.

[0037] The machined curved surface must be able to closely match the curved shape of the wing surface, and no obvious vibration will occur during the machining process. The setting position of the threaded hole can fully fix the wing surface and the tooling, and will not interfere with the work of the machining center during the machining process. In this example, the threaded hole size on the tooling is M6, and the effective depth is 10mm.

[0038] Specific as Figure 5 As shown, the first tooling (i.e., tooling 1) includes a base plate and two types of pressure plates; the base plate includes three parts, the middle part is used for conformal installation with the additive wing surface, and the upper and lower parts are used to fix the first type of pressure plate. The middle part of the first type of pressure plate is an arc surface conformal with the additive wing surface, and the two end parts are used for fixed installation with the upper and lower parts of the base plate; one end of the second type of pressure plate is used for fixed installation with the upper part of the base plate, and the other end presses the joint of the additive wing surface by pressing force. The width of the middle part of the base plate is smaller than the width of the fixed wing surface, and the width difference between the two sides is 5-10mm.

[0039] The second tooling (i.e. tooling 2) includes a bottom plate and a first type of pressing plate; the bottom plate includes three parts, the middle part ( Figure 6 As shown) is installed in a conformal manner with the front face of the additive wing surface, a cylindrical protrusion is provided on it for matching with the circular hole on the joint, and a positioning pin hole is provided for corresponding to the position of the pin hole processed on the joint ( Figure 4 ); the upper and lower parts are used to fix the first type of pressure plate, the middle part of the first type of pressure plate is an arc surface that follows the shape of the additive wing surface, and the two end parts are used to be fixedly installed with the upper and lower parts of the base plate.

[0040] After the corresponding camber and shape of the tooling are machined according to the size of the formed wing surface, the precise camber shape and the clamping requirements and the threaded holes for clamping the workpiece are machined, step 104 is executed.

[0041] Step 104: Analyze the test assembly results of the formed airfoil and the tooling, and optimize the surfaces with loose fit and obstructed processing;

[0042] The fixture can fully fix the wing surface, and all non-machining areas can be supported by the fixture. The tool can feed at an angle that meets the machining requirements without interfering with the measurement of dimensions during the machining process.

[0043] After analyzing the test assembly results of the formed airfoil and the tooling and optimizing the loose fit and the obstructed processing surfaces, step 105 is executed.

[0044] Step 105: Clamp the wing surface onto the tooling 1 (eg Figure 2 As shown in the figure, a three-axis machine tool is used to machine some features on the wing surface.

[0045] Step 106: Use the tooling 1 in step 105 to clamp the tooling 1 and the wing surface on the A-axis turntable of the four-axis machine tool through the positioning mandrel (such as Figure 3 as shown), features on the machined side.

[0046] Step 107: The wing surface is clamped on the fixture 2 by two positioning pins, and further mounted on a three-axis machine tool to process the features on the wing surface flip side (also called the back side), so as to achieve rapid positioning.

[0047] The present invention provides a precision machining method for additive airfoils, which can effectively solve the problem of low dimensional accuracy during mechanical machining of additive airfoils in the prior art, and further improve the dimensional accuracy and machining efficiency of additive airfoils of this type of products.

[0048] This intellectual achievement can solve many existing problems when applied in actual production and has great application prospects.

[0049] The precision machining method of the additive wing surface provided by the implementation of the present invention is aimed at the existing additive wing surface, because the shape of the surface to be machined is irregular, it is impossible to accurately obtain the positioning point, and the margin is small. The implementation of the present invention can effectively solve the problem that the positioning accuracy of the machining coordinate origin is low and the symmetry of the two side walls of the wing surface is poor due to the arc surface of the formed wing surface, and each process can be quickly positioned and clamped, and a continuous processing process can be formed during mass production.

[0050] The above description is only a preferred example of the implementation examples of the present invention and is not intended to limit the implementation examples of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the implementation examples of the present invention should be included in the protection scope of the implementation of the present invention.

[0051] Parts not described in detail in the present invention belong to common knowledge of those skilled in the art.

Claims

1. A precision machining method for an additive airfoil, the additive airfoil comprising a fixed airfoil and a joint; characterized in that include: According to the hardness, rigidity and stress of the additively manufactured wing surface, select the tooling material that meets the clamping and support requirements; According to the structure of the additive wing surface, the basic forms and clamping methods of two toolings are designed, wherein the first tooling is used to process the front side of the additive wing surface and can be clamped on a three-axis or four-axis machine tool, and the second tooling is used to process the back side of the additive wing surface and can be clamped on a three-axis machine tool; According to the size, camber shape and clamping requirements of the additive wing surface, the corresponding camber, positioning holes and threaded holes for clamping of the tooling are processed; the tooling after processing is tightly matched with the additive wing surface, and the rest of the area on the additive wing surface except the area to be processed is in contact with the tooling, and there is no processing obstructed surface; The additive airfoil is clamped on the first fixture, which is clamped on the three-axis machine tool and positioned using the positioning holes, and the front features of the joint are machined according to the final product size; Clamp the first tooling on the machine tool and position it using the positioning holes to process the side features of the joint and the fixed wing surface; The additive airfoil is removed from the first fixture and its back is mounted on the second fixture. The second fixture is clamped on a three-axis machine tool and positioned using positioning holes to machine the back features of the joint according to the final product size.

2. The method according to claim 1, characterized in that: The material hardness of the tooling is not less than the hardness of the additive airfoil, and its rigidity satisfies the need to support the additive airfoil without deformation during processing.

3. The method according to claim 1, characterized in that The first tooling includes a base plate and two types of pressure plates; the base plate includes three parts, the middle part is used for conformal installation with the additive wing surface, the upper and lower parts are used to fix the first type of pressure plate, the middle part of the first type of pressure plate is an arc surface conforming to the shape of the additive wing surface, and the two end parts are used for fixed installation with the upper and lower parts of the base plate; one end of the second type of pressure plate is used for fixed installation with the upper part of the base plate, and the other end presses the joint of the additive wing surface through a clamping force.

4. The method according to claim 3, characterized in that The width of the middle part of the bottom plate is smaller than that of the fixed wing surface, and the width difference between the two on one side is 5-10mm.

5. The method according to claim 1, characterized in that The second tooling includes a base plate and a first type of pressure plate; the base plate includes three parts, the middle part is installed in accordance with the front shape of the additive wing surface, a cylindrical protrusion is arranged on it for matching with the circular hole on the joint, and a positioning pin hole is arranged for corresponding to the position of the processed pin hole on the joint; the upper and lower parts are used to fix the first type of pressure plate, the middle part of the first type of pressure plate is an arc surface that conforms to the shape of the additive wing surface, and the two end parts are used to be fixedly installed with the upper and lower parts of the base plate.

6. The method according to claim 5, characterized in that The gap between the cylindrical protrusion and the corresponding circular hole on the joint is 1-2 mm.

7. The method according to claim 3 or 5, characterized in that: There are multiple first-type pressure plates, which are arranged at the location where the reinforcing ribs are arranged inside the fixed wing surface.

8. The method according to claim 1, characterized in that The machining allowance of the part to be machined on the additively-made wing surface is 2-3 mm.

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