Numerical control machine tool finish machining method for casting parts

Abstract

A numerical control machine tool finish machining method for casting parts is suitable for precision machining of complex mechanism parts in the fields of aerospace, automobile manufacturing and the like and comprises the steps of lineation marking, profile trial cutting, on-machine measurement, error analysis, program adjustment, precision machining and surface treatment. And the machining reference and the origin coordinates are adjusted, a compensated numerical control program is generated, the precision precision and the surface quality of the complex casting part are remarkably improved, and the problems of deformation, overcutting and errors are reduced. The method can improve the assembly precision of products, and is widely applied to the field of machining requirements of high-precision and complex structural parts.

Description

Technical Field

[0001] The invention relates to a CNC machine tool finishing method for casting parts, and belongs to the field of precision machining of complex structural parts in the fields of aerospace, automobile manufacturing, etc. Background Art

[0002] Casting parts face many challenges in the finishing process due to their complex geometry and large size. Traditional machining methods have obvious deficiencies in machining accuracy and surface quality, and are prone to deformation, overcutting, large machining errors and other problems, which seriously affect the assembly accuracy and performance of the product. For example, during the machining process, due to the unevenness of the casting blank, uneven wall thickness cutting is prone to occur, and casting parts are prone to deformation and overcutting, which causes the final product to fail to meet the design requirements. In addition, traditional machining methods have limitations in error compensation and cannot fully guarantee the accuracy of the workpiece. Summary of the invention

[0003] The technical problem solved by the present invention is: in view of the problem that the traditional method of casting parts in the current prior art cannot meet the requirements of design tasks, a CNC machine tool finishing method for casting parts is proposed.

[0004] The present invention solves the above technical problems by the following technical solutions:

[0005] A CNC machine tool finishing method for casting parts, comprising:

[0006] Place the part blank on the bench platform for marking;

[0007] Fix the workpiece after the scribing process on the processing platform, and perform preliminary positioning according to the scribing marks obtained by the scribing process and the design model of the product parts;

[0008] Set the machining origin on the positioned workpiece, perform a test cut on the workpiece contour, and adjust the machining origin based on the test cut results;

[0009] The probe is used to measure the contour of the workpiece after cutting on the machine to obtain the initial shape data;

[0010] Compare the initial topography data with the design model to obtain the workpiece deformation and processing error;

[0011] Calculate the deviation value of all the positions to be processed of the workpiece, compare and analyze it with the deformation of the workpiece, identify the compensation position in the position to be processed according to the analysis results, and reset the processing origin and marking standard;

[0012] Generate compensation code according to the reset machining origin and marking standard;

[0013] Use compensation codes to adjust the NC machining program, determine the machining area according to the position to be machined, and control the machining tool to perform reserve machining through the NC machining program;

[0014] The processed parts are surface treated and tested for accuracy and surface quality.

[0015] The marking method for the part blank is:

[0016] Using the rear end ribs on the bench platform as a reference, the blank is marked with horizontal reference lines, live lines, and symmetry lines as marking marks.

[0017] The method for preliminary positioning is:

[0018] Fix the workpiece after the marking process on the processing platform of the CNC machine tool through the clamping device, and locate all the positions to be processed according to the marking marks and the design model of the product parts to ensure the stability of the processing position;

[0019] Among them, the clamping and fixing position is determined and aligned according to the markings, and the clamping times are twice.

[0020] The method of contour cutting is:

[0021] According to the processing origin position of the workpiece after preliminary positioning, determine the stop of the inner contour of the front end, and perform contour trial cutting according to the stop position and the position to be processed. After cutting, check the cutting situation. If the contour of the workpiece is uniform after cutting, do not adjust the processing origin position. Otherwise, adjust the processing origin position to make the contour of the workpiece uniform after cutting.

[0022] The method to reset the processing origin and marking standard is:

[0023] The motion path of the machining tool is simulated based on the current machining origin, marking standard, and the identified position to be machined; the motion path of the machining tool and the initial topography data are matched. If the match is successful, the current machining origin and marking standard are used as the reset machining origin and marking standard.

[0024] If the matching fails, the machining origin and marking standard are adjusted according to the motion path of the machining tool that can match the initial topography data.

[0025] After the workpiece is processed after the allowance machining, the wall thickness parameters are measured by a wall thickness gauge. According to the product workpiece processing requirements and wall thickness parameters, the allowance machining parameters and CNC machining program are adjusted to perform compensation machining on the current workpiece until the wall thickness parameters meet the product workpiece processing requirements.

[0026] During the stock processing, the stability and accuracy of the processing are ensured by adjusting the processing parameters; the processing parameters include feed parameters and cutting parameters for different processing areas.

[0027] The method for obtaining the initial morphology data is:

[0028] A contact probe is used to collect initial topographic data of the workpiece after cutting. By measuring the geometric data of the workpiece surface after cutting, initial three-dimensional point cloud data is generated as initial topographic data for comparative analysis with the envelope of the design model.

[0029] The surface treatment of the processed parts adopts deburring treatment to ensure the surface quality.

[0030] The design model and integer-controlled machining program are edited and controlled by CAD / CAM software.

[0031] The accuracy and surface quality inspection is implemented by using a three-coordinate measuring machine. The processed parts are inspected and compared with the product workpiece processing requirements. If the product workpiece processing requirements are met, the processing is completed; otherwise, the surface is re-measured on the machine by a probe to obtain current topography data, and the current topography data is used to reset the processing origin and marking standards and adjust the CNC processing program until the re-processed parts meet the product workpiece processing requirements.

[0032] The advantages of the present invention compared with the prior art are:

[0033] (1) The present invention provides a CNC machine tool finishing method for casting parts, which combines on-machine measurement with error analysis to adjust the machining origin to ensure uniform cutting, thereby significantly improving the machining accuracy of casting parts. The machining datum and origin coordinates are adjusted to compensate the NC code, effectively reducing errors in the machining process and reducing accuracy problems caused by deformation or inaccurate positioning.

[0034] (2) The present invention optimizes the machining process by adjusting machining parameters and on-machine measurement, thereby improving work efficiency and reducing rework time. The machining program is adjusted according to the error analysis results so that the motion path of the machining tool can accurately match the actual workpiece morphology, effectively addressing the deformation and overcutting problems that may occur in the workpiece during the machining process.

[0035] (3) The present invention ensures that the final quality of the product meets the design requirements through comprehensive quality inspection. At the same time, it adopts high-precision measuring equipment, CAD / CAM analysis software and precision processing technology to ensure the technical maturity and reliability of the method, providing a stable and reliable solution for casting parts processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of the CNC machine tool finishing method provided by the present invention;

[0037] Figure 2 A schematic diagram of the parts structure provided by the present invention;

[0038] Figure 3 This is a schematic diagram of the horizontal line and symmetry line of the parts provided by the present invention. DETAILED DESCRIPTION

[0039] A CNC machine tool finishing method for casting parts is suitable for the precision machining of complex mechanical parts in the fields of aerospace, automobile manufacturing, etc. The steps include marking, contour trial cutting, on-machine measurement, error analysis, program adjustment, precision machining and surface treatment. By combining on-machine measurement with error analysis, adjusting the machining reference and origin coordinates, and generating a compensated CNC program, the finishing accuracy and surface quality of complex casting parts are significantly improved, and deformation, overcutting and error problems are reduced. This method can improve the assembly accuracy of the product and is widely used in the field of processing requirements for high-precision and complex structural parts.

[0040] The CNC machine tool finishing method for casting parts has the following specific steps:

[0041] Place the part blank on the bench platform for marking;

[0042] Fix the workpiece after the scribing process on the processing platform, and perform preliminary positioning according to the scribing marks obtained by the scribing process and the design model of the product parts;

[0043] Set the machining origin on the positioned workpiece, perform a test cut on the workpiece contour, and adjust the machining origin based on the test cut results;

[0044] The probe is used to measure the contour of the workpiece after cutting on the machine to obtain the initial shape data;

[0045] Compare the initial topography data with the design model to obtain the workpiece deformation and processing error;

[0046] Calculate the deviation value of all the positions to be processed of the workpiece, compare and analyze it with the deformation of the workpiece, identify the compensation position in the position to be processed according to the analysis results, and reset the processing origin and marking standard;

[0047] Generate compensation code according to the reset machining origin and marking standard;

[0048] Use compensation codes to adjust the NC machining program, determine the machining area according to the position to be machined, and control the machining tool to perform reserve machining through the NC machining program;

[0049] The processed parts are surface treated and tested for accuracy and surface quality.

[0050] The marking method for the part blank is:

[0051] Using the rear end ribs on the bench platform as a reference, the blank is marked with horizontal reference lines, live lines, and symmetry lines as marking marks.

[0052] The method for preliminary positioning is:

[0053] Fix the workpiece after the marking process on the processing platform of the CNC machine tool through the clamping device, and locate all the positions to be processed according to the marking marks and the design model of the product parts to ensure the stability of the processing position;

[0054] Among them, the clamping and fixing position is determined and aligned according to the markings, and the clamping times are twice.

[0055] The method of contour cutting is:

[0056] According to the processing origin position of the workpiece after preliminary positioning, determine the stop of the inner contour of the front end, and perform contour trial cutting according to the stop position and the position to be processed. After cutting, check the cutting situation. If the contour of the workpiece is uniform after cutting, do not adjust the processing origin position. Otherwise, adjust the processing origin position to make the contour of the workpiece uniform after cutting.

[0057] The method to reset the processing origin and marking standard is:

[0058] The motion path of the machining tool is simulated based on the current machining origin, marking standard, and the identified position to be machined; the motion path of the machining tool and the initial topography data are matched. If the match is successful, the current machining origin and marking standard are used as the reset machining origin and marking standard.

[0059] If the matching fails, the machining origin and marking standard are adjusted according to the motion path of the machining tool that can match the initial topography data.

[0060] After the workpiece is processed after the allowance machining, the wall thickness parameters are measured by a wall thickness gauge. According to the product workpiece processing requirements and wall thickness parameters, the allowance machining parameters and CNC machining program are adjusted to perform compensation machining on the current workpiece until the wall thickness parameters meet the product workpiece processing requirements.

[0061] During the stock processing, the stability and accuracy of the processing are ensured by adjusting the processing parameters; the processing parameters include feed parameters and cutting parameters for different processing areas.

[0062] The method for obtaining the initial morphological data is:

[0063] A contact probe is used to collect initial topographic data of the workpiece after cutting. By measuring the geometric data of the workpiece surface after cutting, initial three-dimensional point cloud data is generated as initial topographic data for comparative analysis with the envelope of the design model.

[0064] After processing, the surface treatment of the parts is deburred to ensure the surface quality.

[0065] Design models and integer-controlled machining programs are edited and controlled by CAD / CAM software.

[0066] The accuracy and surface quality inspection is realized by using a three-coordinate measuring machine. The processed parts are inspected and compared with the product workpiece processing requirements based on the inspection results. If the product workpiece processing requirements are met, the processing is completed; otherwise, the surface is re-measured on the machine by the probe to obtain the current morphology data. The current morphology data is used to reset the processing origin and marking standards and adjust the CNC processing program until the re-processed parts meet the product workpiece processing requirements.

[0067] The following is further described in conjunction with the accompanying drawings and preferred embodiments of the specification:

[0068] In the current embodiment, a CNC machine tool finishing method for casting parts, such as Figure 1 As shown, the following steps are included:

[0069] Step 1: Draw the horizontal reference line and symmetry plane line on the part blank on the bench platform with the rear end rib as the reference to ensure the accuracy of the reference position of the workpiece and provide a reference for CNC machine tool processing. Figure 3 As shown;

[0070] Step 2: Fix the scribed workpiece on the processing platform of the CNC machine tool to ensure that the blank clamping position is stable;

[0071] Step 3: Use the positioning device of the CNC machine tool to preliminarily position the blank according to the marking, set the processing origin, and perform contour test cutting on the inner contour stop of the front end to check whether the cutting is uniform. Adjust the processing origin according to the cutting situation to ensure uniform cutting. Figure 2 As shown;

[0072] Step 4: After setting the origin, use the probe to measure the surface of the part's outer contour on the machine to obtain its initial shape data;

[0073] Step 5: Compare the measured data with the design model to analyze the deformation and processing error of the parts;

[0074] Step 6: Calculate the deviation value of each area on the workpiece surface and identify the areas that need compensation and adjustment.

[0075] Step 7: Based on the error analysis results, reset the machining origin and reference point of the CNC machine tool to ensure that the motion path of the machining tool accurately matches the actual workpiece morphology;

[0076] Step 8: According to the error analysis results, modify the NC machining program and generate the compensated NC code;

[0077] Step 9: During the processing, carry out the reserve processing. After the processing is completed, use the wall thickness gauge to measure the wall thickness, and then carry out compensation processing according to the wall thickness.

[0078] Step 10: Ensure the stability and accuracy of the machining process by adjusting the machining parameters, including feed parameters and cutting parameters according to different machining areas.

[0079] Step 11: Perform surface treatment on the processed parts to remove burrs generated during the processing to ensure that the surface quality requirements are met;

[0080] Step 12: Conduct a comprehensive inspection on the processed parts to ensure that the accuracy and surface quality meet the design requirements;

[0081] The specific steps are:

[0082] In step one, the casting part blank is fixed on the bench platform, and the part blank is marked on the bench platform using a marking tool to ensure the accuracy of the reference position of the workpiece and provide a reference for CNC machine tool processing.

[0083] According to the marking position, the workpiece is clamped on the processing platform of the CNC machine tool to ensure the stability of the workpiece and perform preliminary positioning, and a trial cut is performed on the inner contour stop at the front end of the part to ensure uniform cutting.

[0084] In step 2, a contact probe is used to collect initial topographic data of the part and generate initial three-dimensional point cloud data for comparison and analysis with the design model.

[0085] In step 3, the collected initial point cloud data is compared and analyzed with the design model. Through analysis, the areas that need compensation and adjustment are identified.

[0086] In step 4, according to the error analysis results, the machining datum of the part is dynamically adjusted, and the machining origin and datum point of the CNC machine tool are reset to ensure that the motion path of the machining tool accurately matches the actual workpiece morphology.

[0087] In step five, according to the error analysis results, the NC machining program is updated to generate compensated NC code. During the machining process, multiple surface compensation machining is performed to ensure uniform wall thickness cutting.

[0088] In step six, the processed parts are surface treated to remove burrs generated during the processing.

[0089] In step seven, a three-coordinate measuring machine is used to conduct a comprehensive inspection of the finished casting parts to ensure that their dimensional accuracy and surface quality meet the design requirements.

[0090] Example: Processing of cast fuel tank parts in the aerospace industry

[0091] The fuel tank parts are cast aluminum, and the product structure is a U-shaped thin-walled part with a height of 300mm and a minimum wall thickness of 3mm. The overall outer surface of the part has a casting allowance of 5mm, and the rear end of the part is connected with ribs. The overall processing is based on the rib surface for marking.

[0092] Step 1: Initial positioning

[0093] Material preparation: Place the casting blank on the bench platform.

[0094] Marking: 1. Use a center point to support the large outer surface of the workpiece on the bench platform, level the two small surfaces, and ensure the parallelism between the internal ribs at the rear end and the two small surfaces. The median deviation of the parallelism is not greater than 0.5. Use the rib surface as a reference to return to the horizontal reference line and mark the circle. Use this line as a reference to mark the live line between the upper surface of the part and the lower small platform. 2. Stand up the workpiece, use a square ruler to align the horizontal line, use the rear end surface ribs as a reference, mark the live line on the rear end surface, and use this line as a reference to return to the live line of the large plane of the inner cavity of the end face of the workpiece. 3. Use a square ruler to align the horizontal line and the end surface line, and use the rear end grid ribs as a reference to draw the symmetry line along a circle. Ensure that the horizontal and symmetrical positions of the workpiece are accurate.

[0095] Step 2: Fix the workpiece

[0096] Fix the workpiece: Use a fixture to fix the scribed workpiece on the processing platform of the CNC machine tool. Align the workpiece according to the scribed position. The workpiece is processed on all sides and needs to be clamped twice. The first clamping is to process the front features and outer contour of the workpiece, and the second clamping is to process the rear face and rear internal rib features of the workpiece.

[0097] Step 2: Trial cutting of the outline

[0098] To ensure the accuracy of processing, the inner contour of the front end stop of the workpiece is cut before formal processing to check whether the wall thickness is cut evenly, and the processing origin coordinates are fine-tuned as the initial coordinates.

[0099] Step 3: On-machine measurement

[0100] Data acquisition: Use a contact probe to measure the casting parts on the machine. First, use the initial origin coordinates of the pliers test cut as the initial measurement origin, measure the curve of the inner contour of the front end of the part, calculate the precise origin coordinates based on the measurement data, analyze the deviation between the initial origin coordinates and the calculated origin coordinates, and update the origin coordinates as the processing origin. Measure the surface of the processing surface to generate the initial 3D point cloud data of the processing surface.

[0101] Step 4: Error Analysis

[0102] Data comparison: Use CAD / CAM software to compare the measured surface data with the design model.

[0103] Step 5: Processing benchmark adjustment

[0104] Benchmark adjustment: According to the error analysis results, adjust the processing benchmark. Reset the processing origin and benchmark of the CNC machine tool.

[0105] Step 6: Precision Machining

[0106] Program update: Update the machining program according to the test cutting results, perform curve or surface compensation on the machining program, and generate compensated NC code to perform precision machining on the workpiece.

[0107] Step 7: Surface treatment

[0108] Deburring: Use a pneumatic deburring machine to remove burrs generated during machining.

[0109] Step 8: Quality Inspection

[0110] Comprehensive inspection: Use high-precision three-dimensional coordinate measuring machines to conduct comprehensive inspections on the processed parts.

[0111] Implementation Results

[0112] Through the above steps, the machining accuracy of casting parts is guaranteed. Errors, overcutting and deformation problems are effectively controlled, and the assembly accuracy and performance of the product are improved.

[0113] In this embodiment, accurate geometric data is obtained by a contact probe to ensure the accuracy of the initial morphology and achieve high-precision measurement. By adjusting the processing reference and modifying the NC code, the processing error is effectively reduced and error compensation is achieved. By adjusting the processing parameters, the processing efficiency is improved, the rework time is reduced, and the surface quality after processing is guaranteed. The method flow of this embodiment is not only applicable to the aerospace field, but can also be widely used in the precision processing of complex structural parts such as automobile manufacturing.

[0114] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0115] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A CNC machine tool finishing method for casting parts, characterized in that include: Place the part blank on the bench platform for marking; Fix the workpiece after the scribing process on the processing platform, and perform preliminary positioning according to the scribing marks obtained by the scribing process and the design model of the product parts; Set the machining origin on the positioned workpiece, perform a test cut on the workpiece contour, and adjust the machining origin based on the test cut results; The probe is used to measure the contour of the workpiece after cutting on the machine to obtain the initial shape data; Compare the initial topography data with the design model to obtain the workpiece deformation and processing error; Calculate the deviation value of all the positions to be processed of the workpiece, compare and analyze it with the deformation of the workpiece, identify the compensation position in the position to be processed according to the analysis results, and reset the processing origin and marking standard; Generate compensation code according to the reset machining origin and marking standard; Use compensation codes to adjust the NC machining program, determine the machining area according to the position to be machined, and control the machining tool to perform reserve machining through the NC machining program; The processed parts are surface treated and tested for accuracy and surface quality.

2. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The marking method for the part blank is: Using the rear end ribs on the bench platform as a reference, the blank is marked with horizontal reference lines, live lines, and symmetry lines as marking marks. The method for preliminary positioning is: Fix the workpiece after the marking process on the processing platform of the CNC machine tool through the clamping device, and locate all the positions to be processed according to the marking marks and the design model of the product parts to ensure the stability of the processing position; Among them, the clamping and fixing position is determined and aligned according to the markings, and the clamping times are twice.

3. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The method of contour cutting is: According to the processing origin position of the workpiece after preliminary positioning, determine the stop of the inner contour of the front end, and perform contour trial cutting according to the stop position and the position to be processed. After cutting, check the cutting situation. If the contour of the workpiece is uniform after cutting, do not adjust the processing origin position. Otherwise, adjust the processing origin position to make the contour of the workpiece uniform after cutting.

4. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The method to reset the processing origin and marking standard is: The motion path of the machining tool is simulated based on the current machining origin, marking standard, and the identified position to be machined; the motion path of the machining tool and the initial topography data are matched. If the match is successful, the current machining origin and marking standard are used as the reset machining origin and marking standard. If the matching fails, the machining origin and marking standard are adjusted according to the motion path of the machining tool that can match the initial topography data.

5. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: After the workpiece is processed after the allowance machining, the wall thickness parameters are measured by a wall thickness gauge. According to the product workpiece processing requirements and wall thickness parameters, the allowance machining parameters and CNC machining program are adjusted to perform compensation machining on the current workpiece until the wall thickness parameters meet the product workpiece processing requirements.

6. A CNC machine tool finishing method for casting parts according to claim 5, characterized in that: During the stock processing, the stability and accuracy of the processing are ensured by adjusting the processing parameters; the processing parameters include feed parameters and cutting parameters for different processing areas.

7. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The method for obtaining the initial morphology data is: A contact probe is used to collect initial topographic data of the workpiece after cutting. By measuring the geometric data of the workpiece surface after cutting, initial three-dimensional point cloud data is generated as initial topographic data for comparative analysis with the envelope of the design model.

8. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The surface treatment of the processed parts adopts deburring treatment to ensure the surface quality.

9. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The design model and integer-controlled machining program are edited and controlled by CAD / CAM software.

10. A CNC machine tool finishing method for casting parts according to claim 1, characterized in that: The accuracy and surface quality inspection is implemented by using a three-coordinate measuring machine. The processed parts are inspected and compared with the product workpiece processing requirements. If the product workpiece processing requirements are met, the processing is completed; otherwise, the surface is re-measured on the machine by a probe to obtain current topography data, and the current topography data is used to reset the processing origin and marking standards and adjust the CNC processing program until the re-processed parts meet the product workpiece processing requirements.

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