An adaptive preparation method for ceramic core soft core support based on additive and subtractive composite processing

Abstract

The present invention relates to an adaptive preparation method for ceramic core soft core supports based on additive and subtractive composite processing, belonging to the technical field of precision casting for hollow turbine blades for aircraft engines. The method comprises the following steps: individual ceramic core surface detection and error analysis, adaptive calculation of soft core support dimensions and alignment calibration for individual ceramic core surface soft core supports; conformal printing of individual ceramic core surface soft core supports; NC milling of the soft core supports, and testing and evaluation of soft core support molding accuracy and surface quality. The present invention addresses the impact of individual ceramic core surface manufacturing errors on the wall thickness of the blade wax mold by utilizing soft core supports of different sizes to compensate for this thickness, thereby overcoming technical issues with existing methods of preparing ceramic core surface soft core supports, such as poor molding accuracy, dimensional control, and alignment deviation.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision casting of hollow turbine blades for aircraft engines, and in particular relates to an adaptive preparation method of a ceramic core soft core support based on additive and subtractive composite processing. 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, into a wax mold. Its position within the mold cavity is adjusted, and the wax pattern with the ceramic core is pressed. Subsequently, the wax pattern with the ceramic core is then cast through shelling, dewaxing, sintering, casting, core removal, and heat treatment to produce the zero-residue precision casting blank. Under the premise of stable material and process control, the wall thickness accuracy of the blade is primarily inherited from the wax pattern wall thickness accuracy and is ensured by the matching relationship between the ceramic core and the mold cavity surface. Currently, the ceramic core is primarily positioned within the mold cavity 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 accurately fitting soft core supports of different sizes and thicknesses to control 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 turbine blade precision casting wax patterns, a rigid 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 the blade, 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 flexible core support also require precise adjustment. Furthermore, the rigid core support of uniform thickness currently used can cause fractures in the ceramic core surface during the wax pressing process due to dimensional accuracy and material influences, thus affecting the wall thickness deviation of the precision casting wax pattern and its production efficiency.

[0004] Prior art discloses methods for preparing soft core supports for ceramic cores of turbine blades. These methods utilize FDM principles based on the physical properties of the wax material to fabricate the soft core supports for the ceramic core mold surface. Other methods disclose methods for processing soft core supports for ceramic cores of turbine blades. These methods utilize three-coordinate CNC milling of the wax soft core supports bonded to the ceramic core mold surface, thereby improving the consistency of the bond points between the soft core support and the ceramic core. These two methods each ensure consistent bond points and dimensional accuracy. However, due to the complex free-form surfaces of the ceramic core itself, individual core surface errors can affect the wall thickness accuracy of the wax mold, necessitating compensation by varying the soft core support dimensions. This means that individual core support dimensions vary. Furthermore, due to the high wall thickness accuracy requirements of the blade precision casting wax mold, the separate steps of printing and milling the soft core supports can affect the dimensional accuracy of the mold due to clamping errors. Therefore, in order to account for individual core surface errors and eliminate the impact of clamping errors on the dimensional accuracy of the soft core supports, it is urgent to explore new methods for adaptive preparation of ceramic core soft core supports based on additive and subtractive composite machining. Summary of the Invention

[0005] Technical issues to be solved:

[0006] To overcome the shortcomings of the prior art, the present invention provides an adaptive preparation method for ceramic core soft core supports based on additive and subtractive composite processing. This method uses a theoretical ceramic core profile as a standard to determine the manufacturing error of the individual ceramic core profile, thereby determining the actual position of the soft core support and adaptively determining the structure of the soft core support for the actual individual ceramic core profile. The preparation utilizes an integrated manufacturing system that only requires a single calibration to fully meet the automation requirements of measurement, printing, and processing. This invention addresses the impact of the manufacturing error of the individual ceramic core profile on the wall thickness of the blade wax mold by utilizing soft core supports of different sizes to compensate for this thickness, thus overcoming the technical problems of existing methods in preparing soft core supports for ceramic core profiles, such as poor molding accuracy and dimensional control.

[0007] The technical solution of the present invention is: a method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing, the specific steps of which are as follows:

[0008] Measure the actual ceramic core profile parameters and calibrate the soft core support position;

[0009] Determine the geometric shape of the soft core support based on the surface of the wax mold cavity;

[0010] A soft core support solid blank is prepared by conformal printing. The free-form surface position of the soft core support that fits the ceramic core mold surface is decomposed into a B-spline curve to obtain a printing path. The planar rectangular area located in the middle of the soft core support is printed by plane layering. The free-form surface position that fits the cavity surface is decomposed into a B-spline curve to obtain a printing path.

[0011] Measure the size of the soft core support solid blank to determine the machining allowance for material reduction;

[0012] Soft core support CNC milling processing;

[0013] Testing and evaluation of soft core support forming accuracy.

[0014] A further technical solution of the present invention is: the method for calibrating the position of the soft core support is:

[0015] Based on the measured parameters of the actual ceramic core surface, a simulation model of the individual ceramic core surface is constructed;

[0016] Comparing the simulation model of the individual ceramic core profile with the theoretical ceramic core profile model to obtain the actual individual ceramic core profile manufacturing error;

[0017] Based on the obtained error value, the soft core support fitting point is re-determined on the simulation model of the actual ceramic core surface, thus completing the calibration of the soft core support position.

[0018] A further technical solution of the present invention is: the method for determining the geometric shape of the soft core support is:

[0019] Constructing a rectangular area at the determined soft core support position as the bottom surface of the soft core support, and discretizing the four sides of the rectangular area into point cloud data;

[0020] Calculate the normal direction of each point along its ceramic core surface and project it onto the cavity surface of the wax mold;

[0021] The projection points on the cavity surface are fitted into a spline curve, and the enclosed cavity surface is the upper surface of the soft core support;

[0022] The geometric shape of the soft core support is obtained by stretching the bottom surface of the soft core support to the upper surface of the soft core support.

[0023] A further technical solution of the present invention is: the additive method for preparing the soft core support solid blank is to use an FDM direct writing pneumatic extrusion nozzle with a nozzle diameter of 0.5 mm, and the printing process parameters are: extrusion pressure of 0.015 MPa, heating temperature of 75°C, and moving trajectory speed of 15 mm / s.

[0024] A further technical solution of the present invention is: the method for determining the subtractive machining allowance of the soft core support solid blank is to perform size detection on the soft core support solid blank through point laser, and compare it with the theoretical soft core support size to obtain the size deviation; when the actual size is larger than the theoretical size, determine the size of the CNC milling machining allowance; when the actual size is smaller than the theoretical size, perform size compensation on the soft core support solid blank.

[0025] A further technical solution of the present invention is: the CNC milling processing method of the soft core support is to determine the curved surface processing trajectory of the upper surface of the soft core support through a multi-axis linkage processing system, and then determine the processing trajectory of the side wall plane of the soft core support, connect the local processing trajectories, and obtain the CNC milling processing path of the soft core support; according to the determined processing path, drive the tool movement of the multi-axis linkage processing system, and combine three-dimensional measurement to obtain the finely processed solid soft core support.

[0026] A further technical solution of the present invention is: the multi-axis linkage machining system is a four-axis linkage CNC machining equipment, and the machining process parameters are: the electric spindle speed is 12000r / min; the feed speed is 3000mm / min; and the cooling method is air cooling.

[0027] A further technical solution of the present invention is: the soft core support forming accuracy detection and evaluation method is to use a point laser measuring instrument to detect the processed soft core support, so as to determine that its size meets the theoretical requirements and the error range is guaranteed to be within 0.01mm; then use a tool scanner to detect the actual wax pattern surface roughness, and at the same time detect the roughness of the soft core support upper surface, and compare the two to analyze the actual soft core support processing quality.

[0028] A device for preparing a ceramic core soft core support comprises a support column and a position calibration module, a measurement module, an additive manufacturing module, and a milling processing module integrated thereon, wherein the support column is arranged on a workbench, and the ceramic core to be processed is mounted on the workbench via a fixture and a rotating spindle turntable; the measurement module, the additive manufacturing module, and the milling processing module respectively provide three workstations of measurement, additive manufacturing, and milling processing, and realize motion switching control of the three workstations via host computer control; the surface of the ceramic core is measured by the measurement module, and the collected ceramic core surface point coordinate information is sent to the host computer, and the rotating spindle is controlled to adaptively adjust the position of the ceramic core based on the collected information; the soft core support blank is additively prepared at a position set on the ceramic core surface by the additive manufacturing module; the additively prepared soft core support blank is fine-processed by the milling processing module; and the position calibration module is used to align the three workstations of measurement, additive manufacturing, and milling processing.

[0029] A further technical solution of the present invention is that the position calibration module includes a visual inspection camera for calibrating the relative position relationship between the three workstations of measurement, additive manufacturing, and milling; the visual camera has a single pixel accuracy of 0.0038mm / pix, a detection field of view of 19.4mm*19.4mm, and a working distance of 110mm;

[0030] The calibration method of the position calibration module is:

[0031] 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;

[0032] 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.

[0033] 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;

[0034] Move each workstation to the position of the tool setter and calibrate the Z-direction coordinates by touching the tool setter.

[0035] Beneficial effects

[0036] The beneficial effect of the present invention is that it provides an adaptive preparation method for ceramic core soft core supports based on additive and subtractive composite processing. The additive and subtractive manufacturing of ceramic core soft core supports is accomplished through a three-module manufacturing equipment comprising point laser detection, conformal printing of ceramic core surface soft core supports, and NC milling processing.

[0037] The method of the present invention first uses a point laser module to perform adaptive sampling on the actual individual ceramic core surface, and then obtains the individual ceramic core surface manufacturing error based on the individual ceramic core surface reconstruction result, which can obtain the actual soft core support size, avoiding the error caused by the use of uniform thickness in the existing technology; then, the ceramic core surface soft core support conformal printing module is used to realize the surface layering and path planning of the individual ceramic core surface soft core support, and the process parameters are optimized in combination with the material bonding performance and density of the conformal printing process, so as to obtain the ceramic core surface soft core support conformal manufacturing process parameters (nozzle size: 0.5mm; extrusion pressure: 0.015MPa; heating temperature is 75℃, and moving trajectory speed is 15mm / s). Through the parameter setting, the additive soft core support and the ceramic core surface can be completely fitted together, avoiding The position misalignment caused by poor fitting effect and the failure of position calibration were eliminated; then, the NC milling processing module was used to trim the size, shape and surface quality of the soft core support, and the milling processing parameters were optimized in combination with the physical properties of the soft core support material (processing mode: four-axis linkage; spindle speed: 12000r / min; feed speed: 3000mm / min; cooling method: air cooling). The parameter design was designed in combination with the additive wax, which can maintain the soft core support morphology during subtractive processing; finally, the point laser module was used to detect the forming size of the soft core support, and the adaptive preparation of the ceramic core surface soft core support was completed (the forming size accuracy error was controlled within 0.01mm, and the preparation time of a single ceramic core soft core support was controlled within 10min) to ensure the accuracy requirements of the prepared soft core support.

[0038] The present invention integrates three modules: a point laser detection module, an additive printing module, and an NC milling processing module, and implements the method using a four-axis additive and subtractive composite manufacturing equipment platform. The equipment platform structure includes a support column and a position calibration module, a measurement 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 measurement module, the additive manufacturing module, and the milling processing module respectively provide three workstations: measurement, additive manufacturing, and milling processing. The motion switching control of the three workstations is achieved through host computer control. Through integrated design, the technical problems of existing ceramic core surface soft core support preparation methods, which have poor molding accuracy and dimensional control, are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of the ceramic core profile soft core support adaptive additive and subtractive composite processing method of the present invention

[0040] Figure 2 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;

[0041] Figure 3 This is a schematic diagram of a method for calculating the forming dimensions of a soft core support on a ceramic core profile;

[0042] Figure 4 This is a schematic diagram of the layered soft core support curved surface of the ceramic core profile of the present invention;

[0043] Figure 5 This is a schematic diagram of the soft core support fitting position of the ceramic core profile of the present invention;

[0044] 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

[0045] 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.

[0046] 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.

[0047] In order to realize the adaptive additive and subtractive composite preparation of ceramic core surface soft core support, this example builds a ceramic core surface soft core support additive and subtractive composite preparation equipment platform. Combined with the preparation method, the equipment platform mainly includes: a support column and a position calibration module integrated thereon, a measurement module, an additive manufacturing module, and a milling processing module. The support column is set on the workbench, and the ceramic core to be processed is installed on the workbench through a fixture and a rotating spindle turntable; the measurement module, the additive manufacturing module, and the milling processing module respectively provide point laser detection, additive manufacturing, and milling processing stations, and the motion switching control of the three stations is realized through the host computer control. The specific structure is as follows:

[0048] The device for preparing a ceramic core soft core support adopted in this embodiment includes a support column and a position calibration module, a measurement 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 installed on the workbench through a fixture and a rotating spindle turntable; the measurement 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 host computer control; the surface of the ceramic core is measured by the measurement module, and the collected ceramic core surface point coordinate information is sent to the host 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 of the measurement, additive manufacturing, and milling processing stations is aligned by the position calibration module.

[0049] 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, measurement 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 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.

[0050] 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.

[0051] Preferably, the measurement module is a point laser rangefinder 4, 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, secondary development is carried out during the point laser detection process using API library functions, combined with the actual soft core support additive and subtractive composite production process flow, to ensure accurate position detection and data reading of the sampling points on the individual ceramic core surface. At the same time, the actual soft core support bonding point position is calibrated on the individual ceramic core surface.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Preferably, the ceramic core adaptive fixture 7 is designed with an adjustable knob to ensure adaptive and precise clamping of the ceramic core in accordance with the structural characteristics of the individual ceramic core. Considering the relatively weak structure at the trailing edge, an adjustable side rod is designed to provide auxiliary support to prevent vibration fracture during the material addition and subtraction process.

[0057] Reference Figure 1As shown, the specific steps of the ceramic core profile soft core support adaptive additive and subtractive composite processing method of the present invention are as follows:

[0058] Step 1: Detection of individual ceramic core surface errors and calculation of soft core support geometric dimensions;

[0059] In this example, the actual length of the ceramic core is 93 mm. A point laser measuring instrument is used to sample points on the actual ceramic core surface according to the planned measurement trajectory, and the actual ceramic core surface is reconstructed in three dimensions. A rigid registration algorithm is then used to calculate the deviation between the actual reconstructed ceramic core and the theoretical surface. Next, based on the empirical layout of the ceramic core soft core support, the soft core support fitting points are calibrated on the reconstructed ceramic core surface, and the soft core support dimensions applicable to the individual ceramic core surface are recalculated.

[0060] Specifically, refer to Figure 5 As shown in the figure, the soft core support bonding points are distributed at sections II, V, and VIII of the ceramic core. Based on the theoretical soft core support bonding 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 location, the soft core support is thinner at this location due to manufacturing errors on the ceramic core profile. Finally, the actual position of the soft core support is calibrated and the coordinates of the point are recorded.

[0061] Step 2: Determine the geometric dimensions of the ceramic core profile soft core support;

[0062] Since the soft core support is a wax patch between the ceramic core surface and the wax mold cavity surface, the lower surface of the soft core support is the ceramic core surface, and the upper surface is the wax mold cavity surface. The projection planes of the soft core support fitting point on the upper and lower surfaces are both rectangular. With the current soft core support fitting point as the center, make a rectangle with a length of 5mm and a width of 4mm. 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 its ceramic core surface onto the cavity surface is calculated, forming a new rectangle with vertices 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, and the height of the center fitting point is the current soft core support size, such as Figure 3 shown.

[0063] Step 3: Determine the processing sequence of the soft core support additive and subtractive composite preparation;

[0064] 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.

[0065] Step 4: Common preparation of the ceramic core surface soft core support blank. Analyze the soft core support preparation material and determine the printing process parameters and printing trajectory;

[0066] According to the size and geometric shape of the soft core support, the actual soft core support is first layered and sliced. Since the lower surface of the soft core support is the ceramic core surface and the upper surface is the model cavity surface, both are free-form surfaces. Therefore, this embodiment establishes a surface layering method.

[0067] First, the surface of the actual ceramic core surface soft core support model is layered, and the soft core support is divided into two parts. The first part is the free surface position that fits the ceramic core surface, and the second part is the rectangular area of ​​the soft core support. Figure 4 The first part can be regarded as the differential of the NUBRS surface under the soft core support size, and its printing path can be decomposed into B-splines; the second part is the plane layering under the regular shape.

[0068] Then, wax filling is performed based on the layering results of the soft core support. The method used is an FDM direct-writing pneumatic extrusion nozzle. Due to the influence of the material's own characteristics and the curvature of the ceramic core surface, a nozzle diameter of 0.5mm is selected. In combination with the adhesion mechanism of the two materials during conformal printing, the soft core support preparation material is the same material as the investment casting wax pattern, which has low thermal diffusivity and shrinkage, and is a medium-temperature wax. The process parameters are: extrusion pressure of 0.015MPa; heating temperature of 75℃, and movement trajectory speed of 15mm / s. A reciprocating trajectory from outside to inside is used for soft core support printing trajectory planning. Since the ceramic core surface is a free-form surface, a four-axis linkage method is used for overall printing path planning.

[0069] Since the bottom of the soft core support is a free-form surface, a four-axis four-linkage method is used to plan the layered printing path of the soft core support surface. Assuming that the thickness of the soft core support at a certain point is 3mm, it is divided into 10 layers and a reciprocating trajectory from the outside to the inside is used to plan the printing trajectory of the soft core support.

[0070] Step 5: Detect the size of the soft core support blank;

[0071] A point laser measuring instrument is used to inspect the upper surface of the soft core support blank to determine the actual fitting point location and size. This is compared with the theoretical calculated value to determine the milling allowance. If the actual size is greater than the theoretical size, the CNC milling allowance is determined; otherwise, dimensional compensation is performed on the existing soft core support.

[0072] Step 6: Milling of soft core support and determination of processing parameters;

[0073] Since the upper surface of the soft core support fits the inside of the mold cavity (i.e., the mold cavity surface is a free-form surface), CNC milling is required to achieve curved surface processing. The soft core support is made of wax material used for investment casting wax patterns, which has low thermal diffusivity and shrinkage, and is a medium-temperature wax. The amount of milling removal is determined based on the actual size results. The actual soft core support size is rectangular blocks.

[0074] A four-axis platform is used to mill the soft core support. According to the machine tool structure, the ceramic core soft core support is parallel to the Y axis, and the tool axis vector is the Z axis. A high-speed steel ball head milling cutter with a ball head radius of 4mm is selected; the tool shank is 75mm long; and 2 teeth are selected to facilitate chip removal.

[0075] 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.

[0076] Step 7: Detect the forming size and surface quality of the soft core support;

[0077] After milling, recheck the soft core support according to the method in step 5 to confirm that its dimensions meet theoretical requirements and are within a tolerance of 0.01mm. If the dimensional accuracy error does not exceed 0.01mm, the soft core support is considered to have met the requirements; otherwise, a second milling process is performed. Because the upper surface of the soft core support fits the mold cavity, its surface quality should be close to that of the blade wax pattern, ensuring that the blade profile will not have defects after casting.

[0078] At the same time, the tool scanner is used to detect the actual wax pattern surface roughness and the upper surface roughness of the soft core support. The two are compared and analyzed to analyze the actual soft core support processing quality, thereby completing the adaptive preparation of the ceramic core soft core support.

[0079] 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 method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing, characterized in that Specific steps: Individual ceramic core surface detection and error analysis; The actual geometric shape and size of the soft core support of the ceramic core surface are calculated in combination with the wax mold cavity; the geometric shape and size calculation method of the soft core support is as follows: a rectangular area is constructed at the determined soft core support position as the soft core support geometric shape, and the four sides of the rectangular area are discretized into point cloud data; the normal direction of each point along the ceramic core surface at that point is calculated and projected onto the cavity surface of the wax mold; the projected points on the cavity surface are fitted into a spline curve, and the enclosed cavity surface is the upper surface of the soft core support; the bottom surface of the soft core support is stretched to the upper surface of the soft core support, thereby obtaining the geometric shape of the soft core support; A soft core support solid blank is prepared by conformal printing. The free-form surface position of the soft core support that fits the ceramic core mold surface is decomposed into a B-spline curve to obtain a printing path. The planar rectangular area located in the middle of the soft core support is printed by plane layering. The free-form surface position that fits the cavity surface is decomposed into a B-spline curve to obtain a printing path. Measuring the size of a soft core support solid blank to determine a subtractive machining allowance; the method for determining the subtractive machining allowance of the soft core support solid blank comprises: performing size detection on the soft core support solid blank by using a point laser, and comparing the size with a theoretical soft core support size to obtain a size deviation; when the actual size is larger than the theoretical size, determining the size of the CNC milling machining allowance; when the actual size is smaller than the theoretical size, performing size compensation on the soft core support solid blank; Soft core support CNC milling processing; Testing and evaluation of soft core support forming accuracy.

2. The method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing according to claim 1, characterized in that: The method for calibrating the position of the soft core support is: Based on the measured actual ceramic core surface parameters, the three-dimensional model of the individual ceramic core surface is reconstructed; Performing model registration on the three-dimensional reconstructed model of the individual ceramic core surface and the theoretical ceramic core surface model to obtain the actual ceramic core surface manufacturing error; Based on the error analysis results of the individual ceramic core profile, the soft core support fitting points are re-determined on the simulation model of the actual ceramic core profile, thus completing the calibration of the soft core support position.

3. The method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing according to claim 2, characterized in that: The additive method for preparing the soft core support solid blank is a conformal printing process, using an FDM direct writing pneumatic extrusion nozzle with a nozzle diameter of 0.5 mm. The printing process parameters are: extrusion pressure of 0.015 MPa, heating temperature of 75°C, and moving trajectory speed of 15 mm / s.

4. The method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing according to claim 3, characterized in that: The CNC milling processing method for the soft core support is to determine the curved surface processing trajectory of the upper surface of the soft core support through a multi-axis linkage processing system, then determine the processing trajectory of the side wall plane of the soft core support, connect the local processing trajectories, and obtain the CNC milling processing path of the soft core support; according to the determined processing path, drive the tool movement of the multi-axis linkage processing system, and combine with three-dimensional measurement to obtain the finished solid soft core support.

5. The method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing according to claim 4, characterized in that: The multi-axis linkage machining system is a four-axis linkage CNC machining device, and the machining process parameters are: the electric spindle speed is 12000r / min; the feed speed is 3000mm / min; and the cooling method is air cooling.

6. The method for adaptively preparing a ceramic core soft core support based on additive and subtractive composite processing according to claim 1, characterized in that: The soft core support forming accuracy detection and evaluation method is to use a point laser measuring instrument to detect the processed soft core support to determine that its size meets the theoretical requirements and the error range is guaranteed to be within 0.01mm; then use a tool scanner to detect the surface roughness of the soft core support on the ceramic core mold surface, and compare and analyze it with the surface roughness of the precision casting wax mold, and finally evaluate the actual surface quality of the soft core support processing.

7. A device for preparing a ceramic core soft core support, characterized in that: Used to implement the adaptive preparation method of ceramic core soft core support based on additive and subtractive composite processing as described in any one of claims 1-6; it includes a support column and a position calibration module, a measurement module, an additive manufacturing module, and a milling processing module integrated thereon, the support column 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 measurement 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 upper computer control; the surface of the ceramic core is measured by the measurement 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.

8. The device for preparing a ceramic core soft core support according to claim 7, 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 measurement, additive manufacturing, and milling. 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. 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 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; Move each workstation to the position of the tool setter and calibrate the Z-direction coordinates by touching the tool setter.

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