A hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform

Abstract

The present invention relates to a hollow turbine blade ceramic core and soft core support additive and subtractive composite processing platform, which belongs to the technical field of precision casting of hollow turbine blades for aircraft engines; it comprises a support column and a visual camera alignment module, a point laser detection module, an additive manufacturing module and a milling processing module. The support column is arranged on a workbench, and the ceramic core to be processed is mounted on the workbench through a fixture and a rotating spindle turntable; the visual camera alignment module, the point laser detection module, the additive manufacturing module and the milling processing module respectively provide four working processes: multi-station relative position calibration, ceramic core profile detection, soft core support blank preparation and soft core support milling forming, and the motion switching control of the four station modules is realized through the control of the upper computer; the present invention can realize the adaptive preparation of the soft core support on the ceramic core profile, improve the efficiency of the precise preparation of the soft core support, and reduce the influence of the dimensional accuracy caused by the clamping error.

Description

Technical Field

[0001] The invention belongs to the technical field of precision casting of hollow turbine blades of aircraft engines, and in particular relates to a composite processing platform for adding and subtracting materials using a ceramic core and a soft core support of a hollow turbine blade. Background Art

[0002] Hollow turbine blades are a key component of aircraft engines, and their wall thickness accuracy is a crucial technical indicator for blade safety and stability in service. Due to material and structural limitations, hollow turbine blades are primarily manufactured using zero-residue investment casting. The general process involves placing a ceramic core, which reflects the blade's internal structure, within a wax mold. Its position within the mold cavity is adjusted, and the wax pattern with the ceramic core is pressed. Subsequently, the resulting precision-cast blank of the zero-residue turbine blade undergoes shelling, dewaxing, sintering, casting, core removal, and heat treatment. Under the premise of stable material and process control, the wall thickness accuracy of the blade is primarily inherited from the wax pattern's wall thickness and guaranteed by the matching relationship between the ceramic core and the mold cavity surface. Currently, the ceramic core's position within the mold cavity is primarily adjusted by attaching a soft core support. Given the variable wall thickness of the blade, the accuracy and dimensional precision of the soft core support are particularly important for adjusting the ceramic core's spatial position. Therefore, how to ensure the spatial position of the ceramic core in the mold by precisely fitting soft core supports of different sizes and thicknesses, thereby controlling the wall thickness accuracy of the blade wax mold, is a key bottleneck problem that needs to be solved urgently.

[0003] Currently, in the actual production of precision-cast wax patterns for blades, a soft core support made of resin of uniform thickness is manually attached to the surface of the ceramic core. However, given the variable wall thickness of blades, the wall thickness at the leading and trailing edges of the ceramic core and at the blade base and back of the blade differ significantly. Furthermore, given the manufacturing tolerances of the ceramic core surface, the dimensions of the soft core support must be precisely adjusted. Furthermore, the currently used rigid resin core support of uniform thickness can cause fractures in the ceramic core surface during the mold closing and wax pressing process due to dimensional accuracy and material influences, thus affecting the efficiency of precision-cast wax pattern production.

[0004] The existing soft core support preparation method uses the FDM principle to prepare the ceramic core surface soft core support based on the physical properties of the wax material itself; in addition, the existing technology also discloses a ceramic core soft core support processing method, which uses a three-coordinate method to perform CNC milling on the wax soft core support that is bonded to the ceramic core surface, thereby improving the consistency of the bonding points between the soft core support and the ceramic core. These two methods respectively achieve the consistency of the bonding points of the soft core support and the guarantee of dimensional accuracy. However, since the ceramic core itself is a complex free-form surface, the error of the individual ceramic core surface will also affect the wall thickness accuracy of the wax mold, which needs to be compensated by changing the size of the soft core support, that is, the size of the soft core support of the individual ceramic core surface is different. In addition, since the wall thickness accuracy requirements of the blade precision casting wax mold are relatively high, the preparation of the soft core support by printing and milling in steps will affect the molding dimensional accuracy due to clamping errors. Therefore, in order to combine the individual ceramic core surface errors and eliminate the influence of clamping errors on the dimensional accuracy of the soft core support, it is urgent to develop an adaptive additive and subtractive composite processing platform for precision casting hollow turbine blade ceramic core soft core supports. Summary of the Invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform, which integrates a position calibration module, a point laser detection module, an additive manufacturing module and a milling processing module into one, and can realize the adaptive preparation of soft core supports on the ceramic core surface, thereby improving the precise preparation efficiency of the soft core support and reducing the influence of dimensional accuracy caused by clamping errors; at the same time, the present invention aims at the influence of personalized ceramic core surface manufacturing errors on the wall thickness of the blade wax mold, and uses soft core supports of different sizes to compensate for the thickness thereof, thereby solving the technical problems of the existing ceramic core surface soft core support preparation method in terms of poor molding accuracy, dimensional control and fitting position deviation.

[0007] The technical solution of the present invention is: a hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform, including a support column and a position calibration module, a point laser detection module, an additive manufacturing module, and a milling processing module integrated thereon. The support column is set on a workbench, and the ceramic core to be processed is mounted on the workbench via a fixture and a rotating spindle turntable; the point laser detection module, the additive manufacturing module, and the milling processing module respectively provide three workstations: measurement, additive manufacturing, and milling processing, and motion switching control of the three workstations is achieved through host computer control;

[0008] The ceramic core surface is measured by the point laser detection module, and the collected ceramic core surface point coordinate information is sent to the host computer. According to the collected information, the rotating spindle is controlled to adaptively adjust the ceramic core position;

[0009] The soft core support blank is additively prepared by setting a position on the surface of the ceramic core through the additive manufacturing module;

[0010] Finishing of the soft core support blank prepared by additive manufacturing through the milling processing module;

[0011] The position calibration module is used to align the positions of the three workstations: measurement, additive manufacturing, and milling.

[0012] A further technical solution of the present invention is: the support column is a gantry structure, the spindle box is slidably connected to the crossbeam of the gantry through a horizontal slide rail, the position calibration module, point laser detection module, additive manufacturing module, and milling processing module are all installed on the spindle box, the direction of movement of the spindle box along the horizontal slide rail is defined as the Y-axis, the direction of vertical movement is defined as the Z-axis, the central axis rotating around the Z-axis is defined as the C-axis, and the direction of horizontal movement of the worktable perpendicular to the Y-axis is defined as the X-axis, forming a four-axis CNC system of the composite processing platform; adaptive adjustment of the position and posture of the ceramic core is achieved through the four-axis CNC system.

[0013] A further technical solution of the present invention is: the position calibration module includes a visual detection camera, which is used to calibrate the relative position relationship between the three workstations of point laser detection, additive manufacturing, and milling processing; the single pixel accuracy of the visual camera is 0.0038mm / pix, the detection field of view is: 19.4mm*19.4mm, and the working distance is 110mm.

[0014] A further technical solution of the present invention is: the calibration method of the position calibration module is:

[0015] Lower the printing nozzle of the additive manufacturing module to the working position and perform a "cross" wax printing on the reference plane, which is marked as position A;

[0016] Reset the print head and lower the NC milling spindle of the milling module to the working position. Perform a "cross" milling operation in the reference plane, which is recorded as position B.

[0017] Use the visual inspection camera to take pictures of the platform reference surface, calculate the XY direction deviation at the AB position, and perform coordinate calibration;

[0018] Move each workstation to the position of the tool setter and calibrate the Z-direction coordinates by touching the tool setter.

[0019] A further technical solution of the present invention is: the point laser detection module includes a point laser detector for detecting position information of sampling points on the surface of the ceramic core, with a measurement accuracy of ≤0.005mm.

[0020] A further technical solution of the present invention is that the point laser detector uses the API library function to perform secondary development in the point laser detection process to ensure that it can detect the sampling point position of the individual ceramic core surface and accurately read the data. The specific method is:

[0021] First, we used the API library functions of the point laser software development kit (SDK) and the UG secondary development platform to develop the functional modules for the point laser detection process. The point laser detection function is divided into three functions: I / O trigger detection, data storage, and data output. The operating environment is: Intel Core Ultra7 155H 1.4GHz 32G RAM;

[0022] I / O trigger detection function: Based on the LONG CL3IF_GetSystemConfiguration function in the API library function, the single optical unit detection process is started and stopped. Trigger Count represents the trigger count value, which is used to record the number of triggers.

[0023] Data reading and storage function: The measurement value information is read according to the LONG CL3IF_GetMeasurementData function in the API library function, and the measurement value is stored using the array (OutMeasurementData[3]) in C++.

[0024] Data output function: Since the point laser detection result only represents the relative height in the Z direction, the coordinate position relationship of the equipment motion axis and the angular position relationship of the spindle turntable are introduced in the development process for calculation, so as to obtain the actual sampling point coordinate information and output it. Assume that the actual detection point acquisition data is recorded as: , the equipment platform motion axis coordinate system is: ( ), the spindle rotation angle is recorded as θ Then the data collection result of the current point is expressed as:

[0025]

[0026] Print out all the data;

[0027] Finally, the actual soft core support bonding point position is calibrated on the surface of the individual ceramic core based on the actual sampling results.

[0028] A further technical solution of the present invention is: the additive manufacturing module includes a pneumatic printing nozzle assembly, which is installed on the spindle box through a bracket, including a PVC material barrel, an electronic regulating valve, a PEEK material insulation sleeve, a thermocouple and nozzles of different sizes; the electronic regulating valve is used to achieve dynamic air pressure adjustment and temperature feedback; the barrel contains wax material for printing soft core supports, which is a medium-temperature wax and is granular at room temperature. It needs to be preheated before use to ensure that the wax material is fully melted and reduce the internal bubbles in the molten material to ensure the density of the soft core support molding.

[0029] A further technical solution of the present invention is: the milling processing module includes a CNC machining electric spindle, whose output torque is 0.6 N·m, the maximum speed is 40000rpm, and the circular runout is ≤2μm; the CNC machining electric spindle is equipped with a two-tooth ball-end high-speed steel milling cutter of different sizes,

[0030] A further technical solution of the present invention is: the tooling fixture is installed on the rotating spindle of the rotating spindle turntable, the clamping space of the tooling fixture is adjustable, and ceramic cores of different sizes can be clamped and fixed, and an adjustable push rod is used to auxiliary support the trailing edge of the ceramic core to prevent vibration fracture during the process of adding or subtracting materials; the rotating spindle of the rotating spindle turntable can drive the ceramic core to rotate at different angles to achieve high-precision preparation of soft core supports at the leading edge, trailing edge, blade basin and blade back of the ceramic core.

[0031] A method for preparing a hollow turbine blade ceramic core soft core support using an additive and subtractive composite processing platform, the specific steps of which are as follows:

[0032] Step 1: Use the position calibration module to calibrate the relative position relationship between the three workstations of point laser detection, additive manufacturing, and milling processing;

[0033] Step 2: Use the point laser detection module to detect the ceramic core surface;

[0034] After the ceramic core is clamped in the fixture, the point laser rangefinder is used to perform individual ceramic core surface inspection based on the cross-sectional position according to the set inspection trajectory; by continuously triggering the point laser, real-time sampling is achieved and the actual ceramic core surface data points are collected; at the same time, the soft core support attachment position is calibrated;

[0035] Step 3: Combined with the individual ceramic core surface detection results, the individual ceramic core surface deviation is analyzed, and the soft core support fitting position and geometric dimensions of the individual ceramic core surface are adaptively calculated;

[0036] With the current soft core support bonding point as the center, make a rectangle of set size, and project the rectangle onto the ceramic core molding surface. The vertices of the rectangular area are recorded as: a, b, c, d;

[0037] Discretize the four sides of the rectangle into a point cloud, and calculate the projection of each point along the normal direction of its core surface onto the cavity surface to form a new rectangle vertex recorded as: ;

[0038] The projection points of the upper and lower surfaces are fitted into a spline curve, and the enclosed cavity surface is used as the upper surface of the soft core support, so that the hexahedron is obtained as the actual geometric shape of the soft core support.

[0039] Step 4: Print the soft core support using the additive manufacturing module;

[0040] Based on the geometric calculation results of the soft core support of the individual ceramic core surface, an adaptive layering model of the soft core support under the free-form surface was first established. The four-axis linkage additive printing trajectory was planned according to the layering situation. At the same time, the process parameters were formulated: nozzle size 0.4mm; extrusion pressure 0.15Mpa; barrel temperature: 65℃; movement speed 15mm / s. Finally, the adaptive conformal printing molding preparation of the soft core support of the individual ceramic core surface was achieved.

[0041] Step 5: Detection of the forming size of the soft core support blank;

[0042] Use a point laser measuring instrument to detect the upper surface of the soft core support blank, determine the actual fitting point position size and compare it with the theoretical calculated value, and thus determine the milling allowance;

[0043] Step 6: Use the milling processing module to finish the soft core support blank;

[0044] The tool path trajectory of the soft core support blank for four-axis linkage milling is edited in the software and converted into Gcode instructions through post-processing. At the same time, the tool path simulation and verification is carried out using Vericut software, and finally transmitted to the ceramic core surface soft core support adaptive additive and subtractive composite processing platform to realize the precise preparation of the soft core support; it can ensure that the milling processing accuracy error of the soft core support does not exceed 0.01mm.

[0045] Step 7: Soft core support forming dimensional accuracy inspection;

[0046] Re-inspect the soft core support after milling according to the method in step 5. If the dimensional detection accuracy error does not exceed 0.01mm, it is considered that the soft core support processing meets the requirements; otherwise, perform secondary milling.

[0047] Beneficial effects

[0048] The beneficial effects of the present invention lie in providing an adaptive additive and subtractive manufacturing platform for precision-cast hollow turbine blade ceramic core soft-core supports. The system primarily comprises a marble gantry-style support column, a pneumatic printhead, a high-precision CNC electric spindle, a point laser rangefinder, a visual inspection camera, a rotating spindle (B-axis) turntable with a servo motor, and a dedicated fixture for adaptive ceramic cores. The gantry incorporates a modular multi-station assembly: a multi-station alignment module, a ceramic core surface inspection module, an additive manufacturing module, and an NC milling module.

[0049] Based on the actual additive and subtractive manufacturing process for soft core supports for ceramic core profiles, the platform's integrated design enables multi-station automatic switching and multi-axis adaptive processing of soft core supports. A dedicated fixture enables adaptive clamping of individual ceramic cores. A point laser rangefinder detects individual ceramic core profile error data and adaptively calculates soft core support geometry, enabling adaptive soft core support fabrication through additive and NC milling processing modules. By comparing soft core support fabrication technologies used in separate processes, the integrated equipment achieves dimensional accuracy within 0.01mm for soft core support fabrication, with the full fabrication time for a single ceramic core support being approximately 5-8 minutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a four-axis CNC platform for adaptive additive and subtractive composite processing of ceramic core profile soft core supports of the present invention;

[0051] Figure 2 This is a schematic diagram of the structure of the self-adaptive clamping fixture for ceramic cores of the present invention;

[0052] Figure 3 This is a schematic diagram of the positions of the four modules of the present invention integrated into the spindle box;

[0053] Figure 4 This is a flow chart of the method for adaptively adding and subtracting composite materials for processing a ceramic core profile soft core support according to the present invention;

[0054] Figure 5 This is a schematic diagram of the soft core support fitting position of the ceramic core profile of the present invention;

[0055] Figure 6 This is a schematic diagram of a method for calculating the forming dimensions of a soft core support on a ceramic core profile;

[0056] Explanation of the accompanying symbols: 1. Gantry support column made of marble, 2. Pneumatic printing nozzle assembly; 3. CNC electric spindle; 4. Point laser rangefinder; 5. Visual inspection camera; 6. Rotary spindle (B-axis) turntable with servo motor; 7. Ceramic core adaptive special tooling fixture. DETAILED DESCRIPTION

[0057] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0058] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0059] Based on the existing ceramic core surface soft core support preparation method in terms of poor molding accuracy and dimensional control, in order to ensure the dimensional processing accuracy of the soft core support (the error does not exceed 0.01mm), refer to Figure 1 As shown, the present invention provides an additive and subtractive composite processing platform for a hollow turbine blade ceramic core soft core support, comprising a gantry support column made of marble and a position calibration module, a point laser detection module, an additive manufacturing module, and a milling processing module integrated thereon. The gantry support column made of marble is arranged on a workbench, and the ceramic core to be processed is installed on the workbench through a fixture and a rotating spindle turntable; the point laser detection module, the additive manufacturing module, and the milling processing module respectively provide three workstations of measurement, additive manufacturing, and milling processing, and the motion switching control of the three workstations is realized by the control of the upper computer; the surface of the ceramic core is measured by the point laser detection module, and the collected ceramic core surface point coordinate information is sent to the upper computer, and the rotating spindle is controlled to adaptively adjust the position of the ceramic core according to the collected information; the soft core support blank is additively prepared by setting a position on the ceramic core surface by the additive manufacturing module; the soft core support blank prepared by additive processing is fine-processed by the milling processing module; the position calibration module is used to align the three workstations of measurement, additive manufacturing, and milling processing.

[0060] Reference Figure 2 As shown, the marble gantry support column 1 is a gantry structure, the spindle box is connected to the crossbeam of the gantry through a horizontal slide rail, the position calibration module, the point laser detection module, the additive manufacturing module, and the milling processing module are all installed on the spindle box, the direction of movement of the spindle box along the horizontal slide rail is defined as the Y-axis, the direction of vertical movement is defined as the Z-axis, the central axis rotating around the Z-axis is defined as the C-axis, and the direction of horizontal movement of the workbench perpendicular to the Y-axis is defined as the X-axis, forming a four-axis CNC system of the composite processing platform; the four-axis CNC system is used to realize adaptive adjustment of the position and posture of the ceramic core.

[0061] Preferably, the position calibration module is a visual inspection camera 5, which is used to calibrate the relative position relationship between multiple stations. The single pixel accuracy of the visual camera is 0.0038mm / pix, the detection field of view is: 19.4mm*19.4mm, and the working distance is 110mm.

[0062] Preferably, the point laser detection module is a point laser rangefinder 4, which is used to detect the position information of the sampling points on the ceramic core surface, with a measurement accuracy of ≤0.005mm. At the same time, the API library function is used for secondary development in the point laser detection process, and the secondary development is carried out in combination with the actual soft core support additive and subtractive composite preparation process flow to ensure that it can detect the sampling point position of the individual ceramic core surface and accurately read the data. At the same time, the actual soft core support bonding point position is calibrated on the surface of the individual ceramic core. The specific method is:

[0063] First, we used the API library functions of the point laser software development kit (SDK) and the UG secondary development platform to develop the functional modules for the point laser detection process. The point laser detection function is divided into three functions: I / O trigger detection, data storage, and data output. The operating environment is: Intel Core Ultra7 155H 1.4GHz 32G RAM;

[0064] I / O trigger detection function: Based on the LONG CL3IF_GetSystemConfiguration function in the API library function, the single optical unit detection process is started and stopped. Trigger Count represents the trigger count value, which is used to record the number of triggers.

[0065] Data reading and storage function: The measurement value information is read according to the LONG CL3IF_GetMeasurementData function in the API library function, and the measurement value is stored using the array (OutMeasurementData[3]) in C++.

[0066] Data output function: Since the point laser detection result only represents the relative height in the Z direction, the coordinate position relationship of the equipment motion axis and the angular position relationship of the spindle turntable are introduced in the development process for calculation, so as to obtain the actual sampling point coordinate information and output it. Assume that the actual detection point acquisition data is recorded as: , the equipment platform motion axis coordinate system is: ( ), the spindle rotation angle is recorded as θ Then the data collection result of the current point is expressed as:

[0067]

[0068] Print out all the data;

[0069] Finally, the actual soft core support bonding point position is calibrated on the surface of the individual ceramic core based on the actual sampling results.

[0070] Preferably, the additive manufacturing module is a pneumatic printing nozzle assembly 2, which mainly includes a PVC material barrel, an electronic regulating valve, a PEEK material insulation sleeve, a thermocouple, nozzles of different sizes and a high-precision "L"-shaped bracket connected to the platform module.

[0071] The electronic control valve can be developed through a PLC to achieve dynamic air pressure adjustment and temperature feedback. The wax used in investment casting wax patterns is used for soft core support printing. This medium-temperature wax has low thermal diffusivity and shrinkage, and its granular state at room temperature allows for more effective heating and extrusion stability control. Preheating is required before use to ensure full melting of the wax and reduce internal bubbles in the molten material, ensuring a dense, moldable soft core support.

[0072] The milling module preferably includes a CNC electric spindle 3 with an output torque of 0.6 N·m, a maximum speed of 40,000 rpm, and a circular runout of ≤2 μm. Manual tool change is employed. Considering the wax machining and cutting process, a two-tooth ball-end high-speed steel milling cutter with different sizes is provided.

[0073] Preferably, the rotating spindle (B-axis) turntable 6 with a servo motor, combined with the positioning method of the cone hole of the core head of the ceramic core profile and its own structural characteristics, can achieve high-precision additive and subtractive material preparation of the soft core support at the leading edge, trailing edge, blade basin and blade back of the ceramic core by rotating at different angles.

[0074] Preferably, refer to Figure 3 As shown, the ceramic core adaptive fixture 7 is designed with an adjustable knob to ensure adaptive and precise clamping of the individual ceramic core structure. Considering the relatively weak structure at the trailing edge, an adjustable side rod is designed to provide auxiliary support to prevent vibration and fracture during the material addition and subtraction process.

[0075] Reference Figure 4 As shown in the figure, the three workstations on the execution end of the developed precision casting hollow turbine blade ceramic core soft core support adaptive additive and subtractive composite processing platform should be able to switch freely. Combined with the actual ceramic core soft core support adaptive additive and subtractive composite preparation method, and with the cooperation of other auxiliary devices on the platform, the following operations can be completed. The specific steps are as follows:

[0076] Step 1: Clamp the ceramic core and align the machining coordinate system. Use the designed ceramic core fixture to clamp the ceramic core on the B-axis rotary table, and use the tool setter to align the coordinate system to set the machining base.

[0077] Step 2: Detect the size of the ceramic core surface to confirm the actual ceramic core surface soft core support fitting position and size;

[0078] Reference Figure 5 As shown in the figure, in this example, the actual ceramic core length is 93 mm. A point laser is used to sample the ceramic core profile at known locations, and the actual ceramic core profile is reconstructed. Next, a rigid registration algorithm is used to calculate the deviation between the actual reconstructed ceramic core and the theoretical profile. The soft core support fitting points are distributed at sections II, V, and VIII of the core. Based on the theoretical soft core support fitting points, the soft core support dimensions for the actual ceramic core profile are calculated. For one of the soft core supports, the actual dimension calculated is 2.89 mm, while the theoretical dimension at the current point is 3.02 mm. Compared to the theoretical position, the soft core support is thinner at this location due to manufacturing errors in the ceramic core profile. Finally, the actual position of the soft core support is calibrated and the coordinates of that point are recorded.

[0079] Step 3: Determine the geometric shape of the ceramic core leaf basin and the soft core support at the leaf back;

[0080] Reference Figure 6 As shown in the figure, with the current soft core support bonding point as the center, a rectangle with a length of 5mm and a width of 4mm is made. The vertices of the rectangular area projected onto the ceramic core surface are recorded as: a, b, c, d; the four sides of the rectangle are discretized into a point cloud, and the projection of each point along the normal direction of the ceramic core surface onto the cavity surface is calculated to form a new rectangular vertex recorded as: The projection points of the upper and lower surfaces are fitted into a spline curve, and the enclosed cavity surface is used as the upper surface of the soft core support. Thus, the hexahedron is obtained as the actual soft core support geometry.

[0081] Step 4: Determine the processing sequence of the soft core support additive and subtractive composite preparation;

[0082] Based on the platform structure of the soft core support additive and subtractive material equipment, the ceramic core profile structure, and the soft core support position, the soft core support blank is first additively prepared at the ceramic core blade basin. Then, the actual soft core support dimensions and milling allowance are determined through inspection, and finally, the soft core support is milled. Next, the same additive and subtractive material processing and inspection steps are performed on the back of the ceramic core blade. This completes the preparation of the entire ceramic core profile soft core support.

[0083] Step 5: Additive preparation of soft core support blank. Analyze the soft core support preparation material and determine the printing process parameters and printing trajectory;

[0084] In this example, the soft core support is made from the same material used for the investment casting wax pattern, which exhibits minimal thermal diffusivity and shrinkage, making it a medium-temperature wax. A nozzle diameter of 0.3mm and an extrusion pressure of 0.3MPa were used. The heating temperature was 65°C, and the travel speed was 15mm / s. A reciprocating trajectory from outside to inside was used for soft core support printing. Because the ceramic core surface is a free-form surface, a four-axis B-angle linkage was used for overall printing path planning.

[0085] Step 6: Detect the size of the soft core support blank;

[0086] Use a point laser measuring instrument to detect the upper surface of the soft core support blank, determine the actual fitting point position size and compare it with the theoretical calculated value, and thus determine the size of the milling allowance.

[0087] Step 7: Milling of soft core support, determining processing parameters;

[0088] First, the CAM module within UG software was used to program the toolpath for four-axis milling of the soft core support blank. This was converted into Gcode instructions through post-processing, and then simulated and verified using Vericut software. Finally, the toolpath was transferred to the adaptive additive and subtractive machining platform for the ceramic core surface soft core support. Based on the actual soft core support machining allowance and material properties, a high-speed steel ball-end cutter with a 4mm diameter was selected. To facilitate chip removal, a two-tooth tool was selected. The spindle speed was set to 12,000 rpm, the feed rate to 300 mm / min, and the cooling method to air cooling. This completed the CNC milling of the soft core support.

[0089] Step 8: Detection of the dimensional accuracy of the soft core support;

[0090] Re-inspect the soft core support after milling according to step 6. If the dimensional detection accuracy error does not exceed 0.01mm, it is considered that the soft core support processing meets the requirements; otherwise, perform secondary milling.

[0091] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform, characterized by: It includes a support column and a position calibration module, a point laser detection module, an additive manufacturing module, and a milling processing module integrated thereon; the support column and the rotating spindle turntable are installed on the workbench, and the ceramic core to be processed is installed in the spindle turntable through a fixture; the position calibration module, point laser detection module, additive manufacturing module, and milling processing module respectively provide four processes: multi-station relative position calibration, ceramic core surface detection, soft core support blank preparation, and soft core support milling forming, and the motion switching control of the four station modules is realized through the control of the upper computer; The relative positions between the laser detection module, additive manufacturing module and milling processing module on the equipment platform are calibrated through the position calibration module, and different processing coordinate systems are set for each module and recorded in the equipment platform; The ceramic core surface is measured by the point laser detection module, and the collected ceramic core surface point coordinate information is sent to the host computer. According to the collected information, the rotating spindle is controlled to adaptively adjust the ceramic core position; The soft core support blank is additively prepared by setting a position on the surface of the ceramic core through the additive manufacturing module; The soft core support blank prepared by additive manufacturing is finished by milling processing module; The point laser detection module includes a point laser detector for detecting the position information of the sampling points on the ceramic core surface, with a measurement accuracy of ≤0.005mm; The point laser detector uses API library functions to perform secondary development in the point laser detection process to ensure that it can detect the sampling point position of the individual ceramic core surface and accurately read the data. The specific method is as follows: First, the point laser detection process functional module development was implemented using the API library functions of the point laser software development kit SDK and the UG secondary development platform. The point laser detection function was decomposed into three functions: I / O trigger detection, data storage, and data output. The operating environment was: Intel Core Ultra7 155H 1.4GHz 32G RAM; I / O trigger detection function: According to the LONG CL3IF_GetSystemConfiguration function in the API library function, the start and stop control of the single optical unit detection process is performed; Data reading and storage function: Read the measurement value information according to the LONG CL3IF_GetMeasurementData function in the API library function, and use the C++ array to store the measurement value; Data output function: obtain the actual sampling point coordinate information and output it; Assume that the actual detection point collection data is recorded as: , the equipment platform motion axis coordinate system is: , the spindle rotation angle is recorded as , then the data collection result of the current point is expressed as: Then print out all the data; Finally, the actual soft core support bonding point position is calibrated on the surface of the individual ceramic core based on the actual sampling results.

2. The hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform according to claim 1, characterized in that: The support column is a gantry structure, and the spindle box is connected to the crossbeam of the gantry through a horizontal slide rail. The position calibration module, point laser detection module, additive manufacturing module, and milling processing module are all installed on the spindle box. The direction of movement of the spindle box along the horizontal slide rail is defined as the Y-axis, the direction of vertical movement is defined as the Z-axis, the central axis rotating around the Z-axis is defined as the C-axis, and the direction of horizontal movement of the worktable perpendicular to the Y-axis is defined as the X-axis, forming a four-axis CNC system of the composite processing platform; the four-axis CNC system is used to realize adaptive adjustment of the position and posture of the ceramic core.

3. The hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform according to claim 2, characterized in that: The position calibration module includes a visual inspection camera, which is used to calibrate the relative position relationship between the three workstations of point laser inspection, additive manufacturing and milling processing; the single pixel accuracy of the visual camera is 0.0038mm / pix, the detection field of view is: 19.4mm*19.4mm, and the working distance is 110mm.

4. The hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform according to claim 3, characterized in that: The calibration method of the position calibration module is: Lower the print head of the additive manufacturing module to the working position and perform a "cross" wax printing on the reference plane, which is marked as position A. Reset the print head and lower the NC milling spindle of the milling module to the working position. Perform "cross" milling in the reference plane, which is recorded as position B. Use a visual camera to take pictures of the platform reference surface, calculate the XY direction deviation at the AB position, and perform coordinate calibration; Move each workstation to the position of the tool setter and calibrate the Z-direction coordinates by touching the tool setter.

5. The hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform according to claim 2, characterized in that: The additive manufacturing module includes a pneumatic printing nozzle assembly, which is installed on the spindle box through a bracket, including a PVC material barrel, an electronic regulating valve, a PEEK material insulation sleeve, a thermocouple and nozzles of different sizes; the electronic regulating valve is used to achieve dynamic air pressure adjustment and temperature feedback; the barrel contains wax material for printing soft core supports, which is a medium-temperature wax and is granular at room temperature. It needs to be preheated before use to ensure that the wax material is fully melted and reduce internal bubbles in the molten material to ensure the density of the soft core support molding.

6. The hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform according to claim 2, characterized in that: The milling processing module includes a CNC machining electric spindle with an output torque of 0.6 N·m, a maximum speed of 40,000 rpm, and a circular runout of ≤2 μm; the CNC machining electric spindle is equipped with a two-tooth ball-end high-speed steel milling cutter with different sizes.

7. The hollow turbine blade ceramic core soft core support additive and subtractive composite processing platform according to claim 2, characterized in that: The fixture is mounted on the rotating spindle of the rotating spindle turntable. The clamping space of the fixture is adjustable, and ceramic cores of different sizes can be clamped and fixed. An adjustable ejector rod is used to provide auxiliary support for the trailing edge of the ceramic core to prevent vibration and breakage during the process of adding or removing materials. The rotating spindle of the rotating spindle turntable can drive the ceramic core to rotate at different angles, so as to achieve high-precision addition and subtraction of soft core supports at the leading edge, trailing edge, blade basin and blade back of the ceramic core.

8. A method for preparing a hollow turbine blade ceramic core soft core support by using an additive and subtractive composite processing platform according to any one of claims 1 to 7, characterized in that The specific steps are as follows: Step 1: Use the position calibration module to calibrate the relative position relationship between the three workstations of measurement, additive manufacturing, and milling; Step 2: Use the point laser detection module to detect the ceramic core surface; After the ceramic core is clamped in the fixture, the point laser rangefinder is used to perform individual ceramic core surface inspection based on the cross-sectional position according to the set inspection trajectory; by continuously triggering the point laser, real-time sampling is achieved and the actual ceramic core surface data points are collected; at the same time, the soft core support attachment position is calibrated; Step 3: Combined with the individual ceramic core surface detection results, the individual ceramic core surface deviation is analyzed, and the soft core support fitting position and geometric dimensions of the individual ceramic core surface are adaptively calculated; With the current soft core support bonding point as the center, make a rectangle of set size, and project the rectangle onto the ceramic core molding surface. The vertices of the rectangular area are recorded as: a, b, c, d; Discretize the four sides of the rectangle into a point cloud, and calculate the projection of each point along the normal direction of its core surface onto the cavity surface to form a new rectangle vertex recorded as: ; The projection points of the upper and lower surfaces are fitted into a spline curve, and the enclosed cavity surface is used as the upper surface of the soft core support, so that the hexahedron is obtained as the actual soft core support geometry; Step 4: Print the soft core support using the additive manufacturing module; According to the geometric calculation results of the soft core support of the individual ceramic core surface, the adaptive layering model of the soft core support under the free-form surface is first established, and the four-axis linkage additive printing trajectory is planned according to the layering situation. At the same time, the process parameters are formulated: the nozzle size is 0.4mm; Extrusion pressure: 0.15Mpa; barrel temperature: 65℃; moving speed: 15mm / s; ultimately achieving adaptive conformal printing and molding of soft core supports with individual ceramic core profiles; Step 5: Detection of the forming size of the soft core support blank; Use a point laser measuring instrument to detect the upper surface of the soft core support blank, determine the actual fitting point position size and compare it with the theoretical calculated value, and thus determine the milling allowance; Step 6: Use the milling processing module to finish the soft core support blank; The tool path trajectory of the soft core support blank for four-axis linkage milling is edited in the software and converted into Gcode instructions through post-processing. At the same time, the tool path simulation and verification are carried out using Vericut software. Finally, it is transmitted to the ceramic core surface soft core support adaptive additive and subtractive composite processing platform to realize the precise preparation of the soft core support. It can ensure that the forming accuracy error of the soft core support milling does not exceed 0.01mm. Step 7: Soft core support forming dimensional accuracy inspection; Re-inspect the soft core support after milling according to the method in step 5. If the dimensional detection accuracy error does not exceed 0.01mm, it is considered that the soft core support processing meets the requirements; otherwise, perform secondary milling.

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