A method for mirror milling of a variable thickness of an integral box bottom

Abstract

The application provides a whole box bottom variable-thickness mirror milling method, comprising the following steps: S1, collecting an actual inner contour model of an arc-shaped box bottom; S2, determining a milling boundary and an axial milling distance according to a tool diameter; S3, adopting a transverse height reciprocating milling tool path, calculating the number of layers and the width of cutting of the tool path in the height direction according to the axial milling distance and the effective cutting diameter of the tool; S4, generating a plurality of annular milling curves with equal heights according to the number of layers and the width of cutting of the tool path in the height direction; and S5, milling a transition ring area of the box bottom according to the annular milling curves. The application has the beneficial effects that the annular milling curve is constructed through reverse modeling, the variable-thickness mirror milling of the transition ring area of the whole box bottom is realized by using the variable-thickness mirror milling real-time thickness compensation method according to the annular milling curve.

Description

Technical Field

[0001] This invention belongs to the field of milling technology, and in particular relates to a method for integral box bottom variable thickness mirror milling. Background Technology

[0002] After the box bottom is integrally formed, a certain amount of allowance is left on the inner and outer surfaces. After double-sided thinning by machining, the designed surface is achieved. Due to the design characteristics of the box bottom with a large diameter and thin wall thickness, factors such as the product's weak rigidity clamping and random deformation during the machining thinning process affect the accuracy control of the surface and thickness. Using mirror milling can ensure the final thickness. Mirror milling is a milling method that uses the milling cutter at the milling end and the thickness measuring support device at the support end to move synchronously in a mirror motion. It is suitable for machining large thin-walled curved parts. Existing mirror milling can only achieve thinning processing with equal wall thickness due to its thickness compensation mechanism, which can meet the processing needs of most areas of the box bottom.

[0003] However, the thickness of the transition ring and the melon-shaped section at the bottom of the box exhibits a gradual change, often making mirror milling impossible. This presents the following problems: First, the transition ring area at the bottom of the box exhibits a characteristic of varying thickness: the thickness remains constant at the same height but changes at different heights, a feature known as "single-layer uniform thickness, multi-layer varying thickness." Existing mirror milling methods use a support-end thickness gauge for real-time thickness measurement and perform milling based on the deviation between the measured thickness and the target thickness. However, due to the uncertainty in the target thickness caused by its varying thickness characteristics, mirror milling cannot effectively machine this area. Second, traditional turning and milling methods are used to process this area. Due to the large diameter and thin wall thickness of the product, random deformation and tool chatter during processing are unavoidable, often resulting in the machined thickness failing to meet design requirements and hindering precise machining of this area. Summary of the Invention

[0004] In view of this, the present invention aims to propose a method for integral box bottom variable thickness mirror milling, in order to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] The first aspect of this invention provides a method for mirror milling of an integral box bottom with varying thickness, comprising the following steps:

[0007] S1. Collect the actual internal contour model of the curved box bottom;

[0008] S2. Determine the milling boundary and axial milling distance based on the tool diameter;

[0009] S3. For toolpaths using horizontal height reciprocating milling, calculate the number of layers and cutting width of the toolpath in the height direction based on the axial milling distance and the effective cutting diameter of the tool.

[0010] S4. Generate multiple circular milling curves of equal height based on the number of layers and cutting width of the tool path in the height direction;

[0011] S5. Mill the transition ring area of ​​the box bottom according to the annular milling curve.

[0012] Furthermore, in step S1, the inner surface of the arc-shaped box bottom is laser-scanned and reverse-modeled, and the actual inner contour of the transition ring region is obtained by cutting.

[0013] Furthermore, S2 includes the following steps:

[0014] S21. Construct the theoretical outer surface based on the actual internal contour model and theoretical wall thickness;

[0015] S22, The boundary of the equal wall thickness region of the theoretical outer surface of the transition ring is taken as the upper boundary of milling;

[0016] S23. The boundary where the tool fillet is tangent to the horizontal step fillet is taken as the lower boundary of milling;

[0017] S24. Extract the center lines of the tool at the lower and upper boundaries of the milling process. Intersect these two center lines with the actual internal contour model to obtain the upper and lower boundary points of the internal surface. The length of the internal cross-sectional curve at the two boundary points is denoted as the axial milling distance L. d .

[0018] Furthermore, S3 includes the following steps:

[0019] S31. The number of layers n in the height direction of the planned toolpath is calculated using the following formula:

[0020]

[0021] Among them l s For the probe of the support end thickness gauge to measure the width, D e The effective cutting diameter of the tool is given by , the coefficient k is the toolpath overlap coefficient, and L is the axial milling distance.

[0022] S32. Calculate the cutting width using the following formula:

[0023] A e =L / n.

[0024] Furthermore, S5 includes the following steps:

[0025] S51. Set the path point H for each layer of toolpath. i ;

[0026] S52. Calculate the tool position point H based on the modeling software. i The corresponding theoretical thickness δ i ;

[0027] S53. The theoretical thickness of each toolpath layer is set as the margin of the tool path on the actual inner contour model, and the variable thickness of the toolpath on the inner contour surface is generated.

[0028] S54. Milling of the transition ring area of ​​the outer surface is performed by means of real-time thickness measurement compensation.

[0029] Furthermore, S54 includes the following steps: after the layer position of the path point changes in the CNC code, WCON sets the target thickness to realize the variable thickness milling setting of the G code.

[0030] Furthermore, the coefficient k is 0.8-0.9.

[0031] A second aspect of the present invention provides an electronic device including a processor and a memory communicatively connected to the processor and used to store processor-executable instructions, the processor being used to perform the method according to any one of claims 1-7.

[0032] A third aspect of the present invention provides a server including at least one processor and a memory communicatively connected to the processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the processor to cause the at least one processor to perform the method as described in any one of claims 1-7.

[0033] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method described in any one of claims 1-7.

[0034] Compared with the prior art, the integral box bottom variable thickness mirror milling method of the present invention has the following beneficial effects:

[0035] The present invention discloses a method for mirror milling of the overall box bottom with varying thickness. By constructing a ring milling curve through reverse modeling, and using a real-time thickness measurement and compensation method for mirror milling with varying thickness based on the ring milling curve, the method achieves mirror milling of the transition ring area of ​​the overall box bottom with varying thickness. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1This is a schematic diagram of the milling method described in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the cross-sectional structure of the transition ring region in S24 according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the cross-sectional structure of the transition ring region when the number of layers in the height direction is planned according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the cross-sectional structure of the transition ring region in S5 according to an embodiment of the present invention. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0042] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] Example 1:

[0044] like Figure 1 , Figure 2 As shown, a method for mirror milling of a single box bottom with varying thickness includes the following steps:

[0045] S1. Collect the actual internal contour model of the curved box bottom;

[0046] S2. Determine the milling boundary and axial milling distance based on the tool diameter;

[0047] S3. For toolpaths using horizontal height reciprocating milling, calculate the number of layers and cutting width of the toolpath in the height direction based on the axial milling distance and the effective cutting diameter of the tool.

[0048] S4. Generate multiple circular milling curves of equal height based on the number of layers and cutting width of the tool path in the height direction;

[0049] S5. Mill the transition ring area of ​​the box bottom according to the annular milling curve.

[0050] In S1, the inner surface of the arc-shaped box bottom is laser-scanned and reverse-modeled, and the actual inner contour of the transition ring region is obtained by cutting.

[0051] S2 includes the following steps:

[0052] S21. Construct the theoretical outer surface based on the actual internal contour model and theoretical wall thickness;

[0053] S22, The boundary of the equal wall thickness region of the theoretical outer surface of the transition ring is taken as the upper boundary of milling;

[0054] S23. The boundary where the tool fillet is tangent to the horizontal step fillet is taken as the lower boundary of milling;

[0055] S24. Extract the center lines of the tool at the lower and upper boundaries of the milling process. Intersect these two center lines with the actual internal contour model to obtain the upper and lower boundary points of the internal surface. The length of the internal cross-sectional curve at the two boundary points is denoted as the axial milling distance L. d The upper and lower boundary points of the inner surface are obtained by intersecting the two center lines with the reverse inner contour. The length of the inner cross-section curve at the two boundary points is denoted as L. d .like Figure 2 As shown.

[0056] S3 includes the following steps:

[0057] S31, Plan the number of toolpath layers n in the height direction, such as Figure 3 As shown, the calculation formula is as follows:

[0058]

[0059] Among them l s For the probe of the support end thickness gauge to measure the width, D e The effective cutting diameter of the tool is calculated by subtracting twice the tool base angle from the tool diameter. The coefficient k is the toolpath overlap coefficient, and L is the axial milling distance; the coefficient k is between 0.8 and 0.9. Two adjacent toolpaths are larger than the thickness gauge probe's measurement radius to avoid thickness measurement interference during multi-height milling. Toolpath planning reduces the variation in target thickness during milling.

[0060] S32. Calculate the cutting width using the following formula:

[0061] A e =L / n.

[0062] S5 includes the following steps:

[0063] S51. Set the path point H for each layer of toolpath. i , i = 1, 2, ..., n;

[0064] S52. Calculate the tool position point H based on the modeling software. i The corresponding theoretical thickness δ i , i = 1, 2, ..., n;

[0065] S53, Locate the position points of each layer (H) i δ i ),like Figure 4 As shown, according to the toolpath planning of Technique 1, the theoretical thickness of each layer of toolpath is set as the margin of the tool trajectory on the actual inner contour model, and the variable thickness of the toolpath on the inner contour surface is generated.

[0066] S54. Milling of the transition ring area of ​​the outer surface is performed by means of real-time thickness measurement compensation.

[0067] S54 includes the following steps: after the layer position of the path point changes in the CNC code, WCON sets the target thickness to realize the variable thickness milling setting of the G code.

[0068] Steps S1-S4 determine the layer path location point and the target thickness at that location point. The change in the theoretical thickness is then fed back to the CNC system for variable thickness measurement compensation milling in mirror milling.

[0069] In mirror milling systems, the WOCN macro instruction is typically used to set the target thickness value. Conventional mirror milling code usually initializes the WCON instruction at the program header. However, in variable thickness mirror milling of the bottom transition ring region, the target thickness changes with the layer position point. This is achieved by manually setting the target thickness and theoretical thickness δ for each layer path point. i Similarly, it allows the target thickness to change as the layer location changes.

[0070] By constructing a circular milling curve through reverse modeling, and using a real-time thickness measurement and compensation method for variable thickness milling based on the circular milling curve, the variable thickness mirror milling of the overall box bottom transition ring area is realized.

[0071] Example 2:

[0072] An electronic device includes a processor and a memory communicatively connected to the processor and used to store processor-executable instructions, the processor being used to perform the method of any one of claims 1-7.

[0073] Example 3:

[0074] A server includes at least one processor and a memory communicatively connected to the processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the processor to cause the at least one processor to perform the method as claimed in any one of claims 1-7.

[0075] Example 4:

[0076] A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the method of any one of claims 1-7.

[0077] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0078] In the several embodiments provided in this application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of units described above is merely a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The aforementioned units may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for mirror milling of a single box bottom with varying thickness, characterized in that, Includes the following steps: S1. Collect the actual internal contour model of the curved box bottom; S2. Determine the milling boundary and axial milling distance based on the tool diameter; S3. For toolpaths using horizontal height reciprocating milling, calculate the number of layers and cutting width of the toolpath in the height direction based on the axial milling distance and the effective cutting diameter of the tool. S4. Generate multiple circular milling curves of equal height based on the number of layers and cutting width of the tool path in the height direction; S5. Mill the transition ring area of ​​the box bottom according to the annular milling curve; S3 includes the following steps: S31. The number of layers n in the height direction of the planned toolpath is calculated using the following formula: ； in To support the probe of the thickness gauge for measuring width, The effective cutting diameter of the tool is given by , the coefficient k is the toolpath overlap coefficient, and L is the axial milling distance. S32. Calculate the cutting width using the following formula: 。 2. The integral box bottom variable thickness mirror milling method according to claim 1, characterized in that: In step S1, the inner surface of the arc-shaped box bottom is laser-scanned and reverse-modeled, and the actual inner contour of the transition ring region is obtained by cutting.

3. The integral box bottom variable thickness mirror milling method according to claim 1, characterized in that: S2 includes the following steps: S21. Construct the theoretical outer surface based on the actual internal contour model and theoretical wall thickness; S22, The boundary of the equal wall thickness region of the theoretical outer surface of the transition ring is taken as the upper boundary of milling; S23. The boundary where the tool fillet is tangent to the horizontal step fillet is taken as the lower boundary of milling; S24. Extract the center lines of the tool at the lower and upper boundaries of the milling process. Intersect these two center lines with the actual internal contour model to obtain the upper and lower boundary points of the internal surface. The length of the internal cross-sectional curve at the two boundary points is recorded as the axial milling distance. .

4. The integral box bottom variable thickness mirror milling method according to claim 1, characterized in that: S5 includes the following steps: S51. Set the path points for each layer of toolpath. ; S52. Calculate the tool position points using the modeling software. Corresponding theoretical thickness ; S53. The theoretical thickness of each toolpath layer is set as the margin of the tool path on the actual inner contour model, and the variable thickness of the toolpath on the inner contour surface is generated. S54. Milling of the transition ring area of ​​the outer surface is performed by means of real-time thickness measurement compensation.

5. The integral box bottom variable thickness mirror milling method according to claim 4, characterized in that: S54 includes the following steps: after the layer position of the path point changes in the CNC code, WCON sets the target thickness to realize the variable thickness milling setting of the G code.

6. The integral box bottom variable thickness mirror milling method according to claim 1, characterized in that: The coefficient k is 0.8-0.

9.

7. An electronic device comprising a processor and a memory communicatively connected to the processor and used for storing processor-executable instructions, characterized in that: The processor is used to execute the method described in any one of claims 1-6.

8. A server, characterized in that: The method includes at least one processor and a memory communicatively connected to the processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the processor to cause the at least one processor to perform the method as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it implements the method described in any one of claims 1-6.

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