Efficient milling and precision control method for cambered surface contour workpiece

Abstract

The invention discloses an efficient milling and precision control method for a cambered surface contour workpiece. The method comprises the following steps: analyzing and calculating a relational expression of a machining step pitch according to a surface wave crest and cutting relation; determining a machining tool and calculating a machining step pitch by combining machining experience on the basis of the area size, the precision requirement and the material characteristic of the cambered surface contour of the machined surface; based on the parallel tool path, planning a motion track of a machining tool; according to the machining tool path planning and each cambered surface contour point location algorithm, a machining macro program with a parameterized adjustment function is compiled; according to the compiled machining macro program, trial cutting is conducted on the contour surface of the cambered surface to be machined; collecting the machining service life and wear coefficient machining data of the machining cutter in the trial cutting process, and proposing a linear correction scheme for a machining error curve; a sectional type linear compensation function is implanted in a machining macro program; the adjusted machining macro program is implanted into the three-axis numerical control milling equipment, and complete milling machining of the whole cambered surface contour of the workpiece is carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical processing, and in particular to a high-efficiency milling and precision control method for a workpiece with a curved surface profile. Background Art

[0002] In the field of mechanical processing, especially on three-axis CNC milling equipment, milling of high-precision arc surface contour workpieces has always been a technical difficulty in the industry. In order to ensure the quality of the arc surface contour, traditional processing methods use ball cutters for milling. However, the geometric characteristics of the ball cutter determine the mapping relationship between its processing step and the processing surface quality. When the processing step is too wide, it is often affected by the limitation of the tool geometric profile and the mismatch between the cutting speed and the feed speed, which often leads to a decrease in surface quality, such as excessive surface peaks and severe tool marks. At the same time, although too dense a step can improve the surface quality, it will greatly increase the cutting time, and put forward high requirements on the tool life and processing equipment. Therefore, this contradiction is a technical bottleneck problem that has plagued the mechanical processing industry for many years and has never been solved.

[0003] In addition, for some difficult-to-process materials, such as nickel-based alloys, the cutting life of the ball cutter will be seriously affected. During the processing, the operator needs to frequently pay attention to, measure and replace the blade, resulting in low processing efficiency. Especially in the field of copper plate processing, with the upgrading and iteration of products, new products, new problems and new demands have emerged one after another. The processing of curved copper plates has become a huge problem that plagues the quality and efficiency of modified copper plates due to problems such as long time consumption, low efficiency, severe surface cuts, and high roughness. Therefore, there is an urgent need for a new method that can complete the processing of curved surface contour workpieces efficiently and with high precision. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an efficient milling and precision control method for workpieces with curved surface profiles. This method overcomes the defects of traditional processing of workpieces with curved surface profiles, uses curved surface cross-sectional profiles and parallel tool paths, and adopts end mills or drum milling cutters instead of traditional ball cutters for processing. By compiling a parameterizable and adjustable processing macro program, it can adapt to the processing requirements of workpieces with curved surface profiles of different specifications and sizes. At the same time, based on the accumulation of processing data, the relationship between the cutting life of the tool and the wear coefficient is formed, and a tool linear compensation function is embedded in the program to adjust and reduce the processing error of the tool on the entire curved surface caused by wear during the milling process.

[0005] In order to solve the above technical problems, the present invention provides a method for efficient milling and precision control of a curved surface contour workpiece, comprising the following steps: Step 1: According to the geometric dimensional accuracy and surface roughness of the arc surface profile to be processed, the starting point of the arc surface profile is used as the sectioning wave peak calculation position, and the relationship between the processing step distance Fz is deduced through the geometric calculation formula:

[0006] Among them, De is the machining tool diameter, Rth is the wave peak, R is the arc radius, and L is the arc profile length; Step 2: Determine the machining tool and machining step distance. Based on the arc surface contour area size, precision requirements and material properties of the machined surface, and according to machining experience, determine the machining tool diameter De. The machining tool is an end mill or a drum milling cutter. According to the determined machining tool diameter De, combined with the workpiece surface peak Rth requirements, the machining step distance Fz is calculated according to the relationship formula of the machining step distance Fz. Step 3: Plan the machining tool trajectory. Based on the parallel tool path, according to the arc section profile size characteristics and the selected machining tool geometry, plan the machining tool motion trajectory, form the algorithm formula for each arc surface profile point, and make the machining tool quickly reach the machining arc starting point from the safety plane position. Then the machining tool moves to one side of the machining arc vertex by clockwise arc interpolation, and the machining tool moves to the other side of the machining arc vertex by translational linear motion, and then moves to the end side of the machining arc by clockwise arc interpolation. Finally, the tool is retracted and lifted to the safety plane position to complete the closed tool path on the arc section profile. With this closed tool path, translational cycle cutting is performed according to the machining step, that is, the length direction is cyclically displaced in sequence until the entire arc section profile is processed. According to the machining tool trajectory planning, the algorithm formula for each arc surface profile point is obtained; Step 4: Prepare a processing macro program. Use the parametric programming function to prepare a processing macro program with parameterizable adjustment according to the processing tool trajectory planning and the arc surface contour point algorithm. The processing macro program is adjusted according to the measured values ​​of the arc surface contour size and shape to meet the processing requirements of arc surface contours of different specifications and sizes through the relevant assignment parameters in the processing macro program. Step 5: According to the compiled machining macro program, test cutting is performed on the surface of the arc surface to be machined to verify the accuracy of the machining macro program, and the size of the arc surface section profile after the test cutting is measured. By adjusting the machining allowance, machining tool diameter, and cutting amount parameters in the machining macro program, the machining accuracy of the arc surface section profile is ensured; Step 6: Collect the machining data of tool life and wear coefficient during the trial cutting process to form the data relationship between tool cutting life and wear coefficient. Through data processing and analysis, a machining error curve corresponding to machining position and error value is formed. Based on the allowable error conditions, a linear correction scheme is proposed for the machining error curve to provide a basis for linear compensation of arc surface contour machining. Step 7: According to the linear correction scheme, a linear compensation function for machining tools is embedded in the machining macro program. The linear compensation function is based on the wear of the machining tools. During the machining process, the correction value of the single-segment or multi-segment compensation relationship preset in the machining macro program is assigned. Each machining step in the machining process is adjusted according to each proposed machining interval to perform arc surface contour machining, so as to compensate for the machining error caused by the wear of the machining tools and improve the machining accuracy and machining stability. Step 8: The calibrated machining macro program is implanted into the three-axis CNC milling equipment to implement complete milling of the entire arc surface contour of the workpiece.

[0007] Furthermore, the linear correction scheme in step six adopts an approximate curve equation to form a similar curve for correction.

[0008] Furthermore, the linear correction scheme in step six adjusts the value assignment of the machining macro program in advance based on experience, provides the starting position and regular value that need to be corrected and compensated, and reduces the number of adjustments to the machining macro program.

[0009] Since the efficient milling and precision control method for arc surface contour workpieces of the present invention adopts the above-mentioned technical scheme, that is, the method calculates the relationship between the surface wave peak and the cutting relationship, and determines the processing step distance based on the arc surface contour area size, precision requirements and material characteristics of the processed surface, combined with processing experience, determines the processing tool and calculates the processing step distance; based on the parallel tool path, according to the arc surface cross-sectional contour size characteristics and the selected processing tool geometric size, plans the processing tool motion trajectory; according to the processing tool trajectory planning and the arc surface contour point algorithm, compiles a processing macro program with parameterizable adjustment; according to the compiled processing macro program, the arc surface contour surface to be processed is trial-cut; the processing data of the processing tool processing time, life span and wear coefficient during the trial cutting process are collected, and a linear correction scheme is proposed for the processing error curve; a segmented linear compensation function is implanted in the processing macro program; the adjusted processing macro program is implanted into the three-axis CNC milling equipment to implement complete milling processing of the entire arc surface contour of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic diagram of the outline of the curved copper plate; Figure 2 This is a schematic diagram of the surface wave peaks of the curved copper plate after traditional ball cutter milling; Figure 3 Analyze and calculate the relationship between surface wave crest and cutting; Figure 4 This is a schematic diagram of the tool path for arc surface contour machining; Figure 5 It is a schematic diagram of machining error curve and correction line; Figure 6 Plot a partial solution of the machining step length Fz algorithm; DETAILED DESCRIPTION

[0011] The high-efficiency milling and precision control method for a curved surface contour workpiece of the present invention comprises the following steps: Step 1: When the tool moves on the arc profile, its path will be an equidistant curve inscribed in the arc. The wave crest Rth is the height of the protrusion formed at each point of the arc profile due to the movement of the tool on the step Fz. When the tool diameter De and the step Fz are constant, the wave crest changes due to the change of the motion trajectory. Through geometric relationship analysis, it can be concluded that the maximum wave crest is at the starting point of the long side of the arc profile processing; Based on the above analysis, according to the geometric dimensional accuracy and surface roughness of the arc surface profile to be processed, the starting point of the arc surface profile is used as the sectioning wave peak calculation position, and the relationship between the processing step distance Fz is deduced through the geometric calculation formula:

[0012] Among them, De is the machining tool diameter, Rth is the wave peak, R is the arc radius, and L is the arc profile length; Step 2: Determine the machining tool and machining step distance. Based on the arc surface contour area size, precision requirements and material properties of the machined surface, and according to machining experience, determine the machining tool diameter De. The machining tool is an end mill or a drum milling cutter. According to the determined machining tool diameter De, combined with the workpiece surface peak Rth requirements, the machining step distance Fz is calculated according to the relationship formula of the machining step distance Fz. The machining tool usually selects a relatively small diameter end mill or drum milling cutter to ensure product accuracy. For workpieces with difficult-to-cut materials such as nickel-based alloys, a drum milling cutter or an end mill with a large radius design at the tip is preferred. Its unique tip arc design can ensure the wear resistance of the tool during the cutting process while reducing the occurrence of chipping. Tools with too large diameters are not recommended because they are subject to the manufacturing accuracy of the tool and the stability of the tool during use. The specific size can be determined according to the arc size of the processing object. Step 3: Plan the machining tool trajectory. Based on the parallel tool path, according to the arc section profile size characteristics and the selected machining tool geometry, plan the machining tool motion trajectory, form the algorithm formula for each arc surface profile point, and make the machining tool quickly reach the machining arc starting point from the safety plane position. Then the machining tool moves to one side of the machining arc vertex by clockwise arc interpolation, and the machining tool moves to the other side of the machining arc vertex by translational linear motion, and then moves to the end side of the machining arc by clockwise arc interpolation. Finally, the tool is retracted and lifted to the safety plane position to complete the closed tool path on the arc section profile. With this closed tool path, translational cycle cutting is performed according to the machining step, that is, the length direction is cyclically displaced in sequence until the entire arc section profile is processed. According to the machining tool trajectory planning, the algorithm formula for each arc surface profile point is obtained; Step 4: Prepare a processing macro program. Use the parametric programming function to prepare a processing macro program with parameterizable adjustment according to the processing tool trajectory planning and the arc surface contour point algorithm. The processing macro program is adjusted according to the measured values ​​of the arc surface contour size and shape to meet the processing requirements of arc surface contours of different specifications and sizes through the relevant assignment parameters in the processing macro program. Step 5: According to the compiled machining macro program, test cutting is performed on the surface of the arc surface to be machined to verify the accuracy of the machining macro program, and the size of the arc surface section profile after the test cutting is measured. By adjusting the machining allowance, machining tool diameter, and cutting amount parameters in the machining macro program, the machining accuracy of the arc surface section profile is ensured; Step 6: Collect the machining data of tool life and wear coefficient during the trial cutting process to form the data relationship between tool cutting life and wear coefficient. Through data processing and analysis, a machining error curve corresponding to machining position and error value is formed. Based on the allowable error conditions, a linear correction scheme is proposed for the machining error curve to provide a basis for linear compensation of arc surface contour machining. Step 7: According to the linear correction scheme, a linear compensation function for machining tools is embedded in the machining macro program. The linear compensation function is based on the wear of the machining tools. During the machining process, the correction value of the single-segment or multi-segment compensation relationship preset in the machining macro program is assigned. Each machining step in the machining process is adjusted according to each proposed machining interval to perform arc surface contour machining, so as to compensate for the machining error caused by the wear of the machining tools and improve the machining accuracy and machining stability. Step 8: The calibrated machining macro program is implanted into the three-axis CNC milling equipment to implement complete milling of the entire arc surface contour of the workpiece.

[0013] Preferably, the linear correction scheme in step six adopts an approximate curve equation to form a similar curve for correction.

[0014] Preferably, the linear correction scheme in step six adjusts the value assignment of the processing macro program in advance based on experience, provides the starting position and regular value that need to be corrected and compensated, and reduces the number of adjustments of the processing macro program.

[0015] It should be noted that: this method is applicable to the milling processing of various regular curves or contours on the cross section to form arc surfaces, including the milling processing of concave regular extended curved surface contours.

[0016] The following takes the processing of arc copper plate as an example to explain this method in detail. Figure 1 As shown, the guide surface of the curved copper plate 1 adopts a large radius curved surface 11 design, with a radius value of R10285mm, a width of the curved surface 11 of 870mm (the long side width of the curved surface section is 450), a nickel-based alloy coating on the surface, a whole plate length of 1580mm, a surface roughness of Ra3.2, and a curved surface profile error of <0.1mm. Conventional technical solutions all use ball cutters as semi-finishing and finishing tools. Figure 2 As shown in the figure, the geometric characteristics of the ball cutter make the size of its processing step size form a mapping relationship with the surface quality of the workpiece. Due to the high difficulty of processing nickel-based alloys, conventional ball cutter processing cannot withstand long-term cutting requirements, coupled with equipment factors. Only relatively large step lengths can be used for processing to reduce the processing path so that the tool can complete milling of a larger area as much as possible during normal wear. But even so, the processing time has reached the point where multiple tool changes and adjustments are required in the middle to achieve milling of the entire area. Multiple tool changes and adjustments and rapid wear of the tool result in the quality of the arc surface profile cannot be guaranteed. After testing, the arc surface profile error in many places is greater than 0.15mm, the optimal surface wave peak is as high as 18um, and the multiple tool connection cuts are more obvious, which cannot meet the minimum requirements of precision polishing in the next process. In addition, according to statistics, the average semi-finishing and finishing time of the arc copper plate using the traditional ball cutter milling method is 72 to 76 hours in total. Such a long machine processing time cannot meet the needs of on-site production output, which seriously increases the manufacturing cost of the product.

[0017] The method is used to implement the milling process of the arc surface profile of the arc-shaped copper plate, and the specific steps are as follows: S1. Analysis of the relationship between surface wave crest and cutting: Based on the analysis of the tool's contour on the arc surface, according to the geometric dimensional accuracy and surface roughness of the arc surface to be processed, such as Figure 3 and Figure 4 As shown, the machining tool 2 moves from right to left, that is, from point A to point B via circular interpolation instructions, moves to point C via linear interpolation instructions, and then moves to point D via circular interpolation instructions. Taking the starting point of the arc surface contour as the sectioning wave peak calculation position, the arithmetic relationship between the machining step distance Fz and the tool diameter De, wave peak Rth, arc surface radius R, etc. is calculated as follows: Figure 3As shown in the enlarged view in the A direction on the right (this view is the projection view of the machining tool 2 at the starting position of the contour of the arc surface 11), according to the tool diameter De and the tool machining interval step distance Fz (the center distance between the two circles), the relationship between the step distance Fz and the tool diameter De and the distance b between the intersection of the two projected circle contour lines in the vertical direction of the tool interval and the projection circle generatrix can be obtained by graphical method, Pythagorean theorem or analytical calculation method of the circumference equation. Taking the Pythagorean theorem as an example, Figure 6 As shown, point E is the intersection of two projected circles (circle 2 and circle 2'). Draw an auxiliary line connecting OE, and draw a perpendicular line from point E to intersect the center line at point F, and connect OF to form a right triangle OFE. According to the Pythagorean theorem, OE 2 =OF 2 +FE 2 , OE=De / 2, OF=De / 2-b, FE=Fz / 2; Substituting into the calculation, we get: ; Depend on Figure 3 As shown in the main view, a ray is drawn from the center of the arc surface through the tangent point of the tool and the arc surface. The angle between the ray and the vertical direction is α°. Then, according to the trigonometric function, the relationship between the angle α and the radius R of the arc surface and the length L of the arc surface contour can be obtained, that is, sinα=L / R; Finally, during the arc contour motion of the tool, since the arc interpolation of the CNC machine tool adopts the approximation method, the extremely short displacement between movements is composed of an approximate tangent line for the arc surface, so Figure 3 As shown in the enlarged figure a in the upper middle part, the relationship between the peak Rth and the b value can be calculated by drawing a graph according to the tangent line, that is, b=Rth / sinα; Combining the arithmetic relationships obtained from the three, we can derive the relationship between the machining step length Fz and the following equation:

[0018] Among them, the step distance Fz, tool diameter De, wave peak Rth, arc surface radius R, arc surface contour side length L; (The specific geometric construction and its calculation process are knowledge that conventional technicians have already mastered, so they will not be explained in detail here) S2. Determination of machining tool and its pitch: According to the section radius R10285mm, width 870mm (section arc long side width 450) and surface roughness R3.2 of the arc surface to be machined. Considering the nickel-based alloy coating on the arc surface of the copper plate and the technical requirements of profile error <0.1mm, a diameter ⌀32r6 drum milling cutter is used as the machining tool to reduce the influence of the material on the cutting life of the machining tool. At the same time, this diameter tool can also better balance the relationship between machining accuracy, cutting efficiency and tool life. According to the relationship formula of machining pitch Fz, calculate the machining pitch Fz:

[0019] According to the calculation results, taking into account the parameter calculation during programming and the habits during processing, the processing step distance is approximately 6mm; S3. Based on the characteristic dimensions of the arc surface contour and the selected tool geometry, a parallel tool path is used to form the algorithm formula for each contour point, such as Figure 4 As shown, it is planned to make the tool quickly reach point A from the safety plane position, then the tool moves to point B by clockwise arc interpolation, the tool moves to point C by translation and linear motion, and then moves to point D by clockwise arc interpolation, and the tool is retracted and raised to the safety plane position, thereby completing the closed tool path on the section; then with this section tool path, parallel (translation) cyclic cutting is performed according to the processing step, that is, the length direction is cyclically displaced in sequence until the entire plate length is processed; according to this section tool path planning, the center of the arc surface profile section radius R10285mm is taken as the zero point, and based on the actual processing, the processing allowance R0 for adjusting the arc radius and the profile extension R8 for reserving a certain space distance between the tool and the workpiece are respectively added, and the above key profile point relationship algorithms are calculated based on the above; ; Among them, R0~R8 are assignment formulas for various geometric dimensions, R0 is the machining allowance of the contour surface of the arc copper plate, R2 is the tool diameter De, R3 is the radius of the tool tip arc on the tool, R4 is the width of the arc copper plate in the positive direction of Y, R5 is the width of the arc copper plate in the negative direction of Y, R7 is the contour radius of the arc copper plate, and R8 is the contour extension amount before feeding during processing; S4. Based on the algorithm formula, use the parametric programming function to compile a processing macro program with parameterizable adjustment; the program can be adjusted according to the size and shape of the arc surface contour to be processed through processing parameters, such as cutting speed, feed speed, cutting depth, etc., to meet the processing requirements of arc surfaces of different specifications and sizes; the program coordinates are located at the vertex of the arc, and the specific processing macro program is as follows: S5. Section trial cutting and adjustment: According to the programmed machining macro program, the surface to be machined is trial cut to verify the accuracy and feasibility of the machining macro program. At the same time, the arc radius R value and the contour roundness after the trial cutting are measured. The machining allowance R0 in the machining macro program is assigned and adjusted. If the roundness is not good, the tool diameter can be fine-tuned to ensure the accuracy of the section contour. S6. During the semi-finishing and finishing process, it was found that the tool was stable in the first half of the cutting process, the tool wear was not obvious, and the size profile did not fluctuate. However, from the middle and later stages, the tool wear began to appear, and the radius error of the arc size on the surface profile section began to increase. The linear measurement of the vertex of the arc of the surface profile can more intuitively see the change in the profile size after tool wear; Figure 5As shown, the error from the starting point to the 600 position is less than 0.01mm, and then it begins to increase in a parabolic form, and finally the error value at the tail end increases to 0.165mm; By processing and analyzing the error data, a machining error curve is formed (such as Figure 5 As shown in Figure 2), and based on the allowable error conditions, a four-stage linear correction scheme is proposed for the machining error curve; specifically: The first section is from the starting position to the 500 position in the length direction of the whole board. Since the tool wear is small, the error is almost zero, so no compensation is given; The second interval, from the 500 position to the 900 position, performs 0.043mm linear compensation; The third interval, from the 900 position to the 1300 position, performs 0.082mm linear compensation; The fourth interval starts from the position 1300 and ends at the position 1580 along the full length of the board, with a linear compensation of 0.035mm. The specific X-axis length starting point position, considering that the processing step distance should be as close as possible to the multiple relationship of the processing step distance Fz=6mm, the corrected starting point position should be appropriately adjusted accordingly; S7. According to the proposed four-stage linear correction scheme, a tool linear compensation function is correspondingly implanted in the machining macro program; this function can adjust the machining contour of each step in the machining process according to the four-stage correction compensation value pre-set in the program according to the wear of the tool during the machining process, and according to the proposed machining intervals, so as to compensate for the machining error caused by tool wear; this method can further improve the machining accuracy and machining stability; the specific linear compensation procedure is as follows: S8. After completing the above steps (processing and debugging), you can start the complete milling process of the entire arc surface.

[0020] Through the implementation of the above methods, after inspection and processing statistics, the technical indicators and production efficiency have been doubled after improvement, as follows: The surface wave peak is reduced from 18um to 2.35um; The processing error is reduced from the original 0.15mm to 0.03mm; The cutting speed is increased from F1200 VB=1 to F3520 VB=6, and the cutting efficiency is increased by 17.6 times; Processing time: semi-finishing is shortened from 32-34 hours to 12 hours, and finishing is shortened from 40-42 hours to 15 hours; Practice has proved that due to the difference in appearance between drum milling cutters and traditional ball cutters, it can effectively overcome and break the inevitable mapping relationship between the residual size of the surface wave peak and the processing step distance under the original ball cutter milling, forming a subversive change in processing quality and efficiency, and the surface cut marks become smooth and delicate after finishing. The subsequent robot polishing process is therefore eliminated, and only the flat grinder finishing and polishing operation is retained.

[0021] Secondly, the parametric programming method can adapt to the processing and dimensional accuracy adjustment of arc surface contour products of different specifications and sizes. More importantly, the multi-segment linear compensation method proposed in this method effectively solves the problem of difficult-to-process materials that were previously difficult to process due to rapid tool wear, multiple tool changes, and tool adjustments during the processing process, which caused the difficulty in controlling the accuracy of the arc surface contour. This has been fundamentally changed. The original operating mode that required operators to wait and pay attention, intermittent measurements, and timely replacement of blades for adjustment has become history. Instead, it has been replaced by a new "one-button operation" mode that is reliable enough for processing accuracy, which has greatly improved the product processing level and efficiency.

[0022] At present, this method has been applied to the processing of arc-surface products formed by regular curves or contour extensions on various cross-sections, including JFE continuous casting frames and flat head covers. Through the above practical verification, this method can not only significantly improve the processing quality and efficiency of such workpieces, but also has high economic value and wide promotion, and also has a strong reference value for the processing of contour surfaces of other similar products.

[0023] This method overturns the traditional processing methods through innovative processing tool paths and parameterizable processing macro programs, and innovatively realizes the replacement of traditional ball cutters with drum milling cutters or end mills in finishing. Secondly, with the geometric characteristics of drum milling cutters or end mills, compared with ball cutters, they can more effectively balance the relationship between processing step distance and surface quality, thereby significantly shortening the processing time (geometric multiples improve efficiency), solving the key problems of ball cutters causing rapid tool wear and short cutting life due to single-blade cutting, which affects the processing accuracy, and the difficulty in processing larger arc surface contours. The linear compensation function proposed in this method, which is assigned and implanted in the processing program, further ensures high-precision control of the arc surface contour, effectively solves the current situation that the tool wears quickly during the processing of difficult-to-process materials and it is difficult to adjust the compensation correction during the processing process, and overcomes the problem that similar products in the past need to replace tools or blades multiple times during the finishing process, and the accuracy is difficult to control.

[0024] This method substantially improves the efficiency and precision of arc surface contour workpiece machining, showing the advantages of high machining efficiency, good machining quality, and a wide range of applications. It is especially suitable for the machining of arc plates of various metal materials, marking a major advancement in arc surface contour machining technology.

Claims

1. A method for efficient milling and precision control of curved surface contour workpieces, characterized in that The steps include: Step 1: According to the geometric dimensional accuracy and surface roughness of the arc surface profile to be processed, the starting point of the arc surface profile is used as the sectioning wave peak calculation position, and the relationship between the processing step distance Fz is deduced through the geometric calculation formula: ， Among them, De is the machining tool diameter, Rth is the wave peak, R is the arc radius, and L is the arc profile length; Step 2: Determine the machining tool and machining step distance. Based on the arc surface contour area size, precision requirements and material properties of the machined surface, and according to machining experience, determine the machining tool diameter De. The machining tool is an end mill or a drum milling cutter. According to the determined machining tool diameter De, combined with the workpiece surface peak Rth requirements, the machining step distance Fz is calculated according to the relationship formula of the machining step distance Fz. Step 3: Plan the machining tool trajectory. Based on the parallel tool path, according to the arc section profile size characteristics and the selected machining tool geometry, plan the machining tool motion trajectory, form the algorithm formula for each arc surface profile point, and make the machining tool quickly reach the machining arc starting point from the safety plane position. Then the machining tool moves to one side of the machining arc vertex by clockwise arc interpolation, and the machining tool moves to the other side of the machining arc vertex by translational linear motion, and then moves to the end side of the machining arc by clockwise arc interpolation. Finally, the tool is retracted and lifted to the safety plane position to complete the closed tool path on the arc section profile. With this closed tool path, translational cycle cutting is performed according to the machining step, that is, the length direction is cyclically displaced in sequence until the entire arc section profile is processed. According to the machining tool trajectory planning, the algorithm formula for each arc surface profile point is obtained; Step 4: Prepare a processing macro program. Use the parametric programming function to prepare a processing macro program with parameterizable adjustment according to the processing tool trajectory planning and the arc surface contour point algorithm. The processing macro program is adjusted according to the measured values ​​of the arc surface contour size and shape to meet the processing requirements of arc surface contours of different specifications and sizes through the relevant assignment parameters in the processing macro program. Step 5: According to the compiled machining macro program, test cutting is performed on the surface of the arc surface to be machined to verify the accuracy of the machining macro program, and the size of the arc surface section profile after the test cutting is measured. By adjusting the machining allowance, machining tool diameter, and cutting amount parameters in the machining macro program, the machining accuracy of the arc surface section profile is ensured; Step 6: Collect the machining data of tool life and wear coefficient during the trial cutting process to form the data relationship between tool cutting life and wear coefficient. Through data processing and analysis, a machining error curve corresponding to machining position and error value is formed. Based on the allowable error conditions, a linear correction scheme is proposed for the machining error curve to provide a basis for linear compensation of arc surface contour machining. Step 7: According to the linear correction scheme, a linear compensation function for machining tools is embedded in the machining macro program. The linear compensation function is based on the wear of the machining tools. During the machining process, the correction value of the single-segment or multi-segment compensation relationship preset in the machining macro program is assigned. Each machining step in the machining process is adjusted according to each proposed machining interval to perform arc surface contour machining, so as to compensate for the machining error caused by the wear of the machining tools and improve the machining accuracy and machining stability. Step 8: The calibrated machining macro program is implanted into the three-axis CNC milling equipment to implement complete milling of the entire arc surface contour of the workpiece.

2. The high-efficiency milling and precision control method for curved surface contour workpieces according to claim 1 is characterized in that: The linear correction scheme in step six adopts an approximate curve equation to form a close curve for correction.

3. The high-efficiency milling and precision control method for curved surface contour workpieces according to claim 1, characterized in that: The linear correction scheme in step six adjusts the value assignment of the machining macro program in advance based on experience, provides the starting position and regular value that need to be corrected and compensated, and reduces the number of adjustments of the machining macro program.

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