Workpiece machining by means of b-axis lathe
By dividing the toolpath in the B-axis lathe and dynamically adjusting the angular position and feed rate, the problem of inconsistent chip thickness was solved, improving machining efficiency and surface quality, and extending tool life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SIMENS INDASTRI SOFTVEAR INK
- Filing Date
- 2024-10-30
- Publication Date
- 2026-06-19
AI Technical Summary
Existing B-axis lathes lack automatic feed rate calculation when machining non-circular inserts, resulting in inconsistent chip thickness, which affects machining efficiency and surface finish. Furthermore, conventional methods cannot effectively prevent tool collisions.
By dividing the turning toolpath into multiple segments and dynamically adjusting the angular position and feed rate through interpolation calculations, the chip thickness is kept constant. The B-axis lathe processor is used to automatically calculate the feed rate and change the angular position.
It achieves constant chip thickness during machining, improves machining efficiency, surface finish and tool life, reduces tool wear and vibration, and improves machining accuracy and consistency.
Smart Images
Figure CN122249774A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for machining a workpiece using a B-axis lathe, wherein the method involves continuously changing the angular position of the turning tool, and the method includes the following steps: (a) Provide the original contour geometry of the workpiece. (b) Provide the target contour geometry of the workpiece. (c) Provide a predetermined chip thickness as the target chip thickness during processing. (d) Provide the toolpath for the turning tool during machining of the target contour geometry. (e) Provides a preset angular position of the turning tool along the tool path, which ensures that the turning tool can approach the workpiece contour during machining, and the position of the specified tool angle at the preset angular position divides the tool path into segments.
[0002] Furthermore, according to the present invention, a B-axis lathe is provided, including a processor prepared for performing a method. Background Technology
[0003] A B-axis lathe is a type of lathe that includes a B-axis, an additional axis of motion relative to the angular position of the turning tool on the workpiece. In addition to the standard X and Y axes for tool movement, the B-axis allows the rotary tool to rotate or pivot. Due to the rotational movement of the turning tool along the B-axis, the angular inclination of the tool relative to the workpiece's main axis of rotation changes during turning. This rotational movement allows the machine tool to machine geometric shapes without changing the cutting tools, in which conventional turning tools might collide with the rotating workpiece. Changing cutting tools requires additional time. Therefore, B-axis lathes are time-efficient.
[0004] In lathe machining, a constant chip thickness is beneficial for obtaining a consistent and smooth surface finish on the machined parts, reducing tool wear and extending tool life, achieving efficient chip removal, improving dimensional accuracy, and reducing the possibility of vibration, chattering, or other adverse machining phenomena.
[0005] Conventional B-axis lathes do not provide automatic feed rate calculation based on a specified chip thickness. For turning tools with non-circular inserts (especially rhomboid inserts), there is no known solution because automatic feed rate calculation depends on the tool orientation relative to the cutting direction, making it possible to use only one of these techniques.
[0006] A method of the type originally mentioned and which is described in the preamble of claim 1 is known from US 2015 / 346707 A1, US 2022 / 128968 A1 and US 2015 / 205284 A1.
[0007] This invention addresses the problem of improving known workpiece processing methods, enabling further optimizations to address the aforementioned challenges.
[0008] One object of the present invention is to enable machining according to the original method to have dynamic angular position changes and automatic feed rate calculation, preferably so that the machining chip thickness remains substantially constant during machining. Summary of the Invention
[0009] The objective of this invention is achieved by the independent claims. The dependent claims describe advantageous improvements and modifications to the invention.
[0010] More specifically, the present invention proposes a method of the type initially mentioned, which includes the following additional steps: (f) Provide a feed chart that provides the feed rate for a given constant tool angle and a given chip thickness. (g) Divide the toolpath segment into toolpath sub-segments with predefined segment lengths. (h) The angular position at the end point of the segment is determined by interpolation between positions of specified tool angles. (i) The feed rate at the end of the segment is determined by assigning the corresponding preset local angular position to the feed chart. (j) Determine the dynamic feed rate and dynamic angular position change based on the interpolation between the position parameters at the end of the corresponding segment of the toolpath. Furthermore, the machining process ensures that the tool position continuously changes between preset angular positions as the tool moves along the tool path based on a feed calculation based on a specified chip thickness.
[0011] The present invention also relates to a B-axis lathe including a processor designed and prepared to perform the methods as defined above or one of the preferred embodiments described below.
[0012] In the context of this invention, dynamic feed rate calculation means that the feed rate is adjusted according to the angular position of the turning tool, wherein the angular position of the turning tool also changes. The dynamic angular position change of the turning tool is defined accordingly. Ultimately, this means that the angular position and the feed rate change simultaneously, and these changes are aligned with each other in order to maintain a specific, preferably constant, chip thickness during machining.
[0013] In lathe machining, the feed rate refers to the speed at which the cutting tool moves along the workpiece surface during the machining process. It is the rate at which material is removed from the workpiece by the cutting tool.
[0014] In the context of this invention, the feed rate is determined by the workpiece's rotational speed (spindle speed) and the rate at which the cutting tool travels along the workpiece (feed per revolution). The feed rate is a critical parameter affecting the efficiency, accuracy, and surface finish of machining operations, and is used to achieve optimal chip formation, prevent tool wear, and ensure dimensional accuracy. The feed rate should be selected within the range recommended by the tool manufacturer to ensure safe and efficient lathe machining.
[0015] This invention introduces a dynamic interpolation technique that divides each toolpath segment into numerous sub-segments. This interpolation method is based on the angular variation of the turning tool, specifically the angular change of the tool insert relative to the current cutting direction between the start and end points of the segment. The angular change per unit distance can be a parameter determining the interpolation for each segment. By decomposing the path into sufficiently small sub-segments, it becomes feasible to automatically and accurately calculate the appropriate feed rate based on a given chip thickness.
[0016] This invention and its preferred embodiments enhance the overall cutting process by ensuring consistent chip thickness. Consistent chip thickness is a critical factor in lathe machining, where chip breaking during machining is often a priority. Automatic feed rate calculations are valuable when optimizing tool life by maintaining a constant chip thickness, especially when machining hard materials.
[0017] A preferred embodiment provides that, during step (h), the rate of change of angle along the toolpath segment is linear. Specifically, this assumption is reasonable for simplifying the determination of intermediate angular positions.
[0018] A preferred embodiment provides that, during step (i), a change in linear feed rate and a change in linear angular position are assumed to be used for interpolation between the corresponding segment end position parameters along the segment toolpath.
[0019] A preferred embodiment provides that, during step (j), the linear angular position is assumed to change for interpolation between the corresponding segment endpoint parameters along the segment toolpath. This simplification enables fast and accurate results.
[0020] Another preferred embodiment provides that, during step (g), when segmenting the toolpath into toolpath segments, a predefined segment length is provided through the following steps: - Provides incremental changes to the segment angle. - Determine the difference between the segment angle change and the preset angular position of the segment endpoint. - Divide the segment into sub-segments and distribute the tool angle change of the segment to the angle change portion of the sub-segments, so that each sub-segment has a tool angle change portion that is lower than the sub-segment angle change increment.
[0021] An alternative preferred embodiment provides that, during step (g), when segmenting the toolpath into toolpath segments, a predefined segment length is provided by the following steps: - Provides incremental changes to the segment feed rate. - Determine the change in segment feed rate as the difference between the feed rates at the segment endpoint. - Divide the segment into sub-segments and distribute the segment feed rate change to the feed rate change portion of the sub-segments, such that each sub-segment has a feed rate change portion that is lower than the sub-segment angle change increment.
[0022] Since the feed rate calculation, based on maintaining a constant chip thickness, depends on trigonometric functions, this option may yield more accurate results.
[0023] Another preferred embodiment provides that the segment is divided into sub-segments with equal toolpath lengths. This assumption enables rapid segmentation.
[0024] A similar preferred embodiment provides that the tool angle change of a segment is divided into angle change portions of sub-segments with equal angle changes.
[0025] Another preferred embodiment provides that the tool angle change of a segment is divided into feed rate change portions of sub-segments with equal feed rate changes. This embodiment yields accurate results.
[0026] Another preferred embodiment provides that the turning tool has a rhomboid insert for cutting the material of the workpiece. Other preferred embodiments provide that the turning tool or turning tool insert is shaped like a parallelogram, rhombus, hexagon, rectangle, octagon, pentagon, square, triangle, or triangular. Attached Figure Description
[0027] Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 A block diagram of the method according to the present invention is shown.
[0028] The illustrations in the accompanying drawings are schematic. It should be noted that similar or identical elements may be given the same reference numerals in different locations. Detailed Implementation
[0029] Figure 1 A schematic flowchart illustrating the method according to the present invention is shown. Figure 1 The steps according to the invention are referred to by the same reference numerals (a) to (j) as in the claims.
[0030] Figure 1Illustrated is a method for machining a workpiece WPC by means of a B-axis lathe MCH according to the present invention. The method involves continuously changing the angular position AGP of the turning tool TTL while machining the workpiece at a dynamically changing feed rate FDR.
[0031] To keep the chip thickness CPT of the material removed during lathe machining constant, the method comprises the following steps.
[0032] Step (a) involves providing the original contour geometry RCG of the workpiece WPC.
[0033] Step (b) involves providing the target contour geometry TCG of the workpiece RCG.
[0034] Step (c) involves providing a predetermined chip thickness CPT as the target chip thickness CPT during machining.
[0035] Step (d) involves providing the tool path TPT of the turning tool TTL during machining of the target contour geometry TCG.
[0036] Step (e) involves providing a preset angular position PAP of the turning tool TTL along the tool path TPT, which ensures that the turning tool TTL can approach the contour of the workpiece WPC during machining MCH, and the position of the specified tool angle TAP of this preset angular position PAP divides the tool path TPT into segments SGT.
[0037] Step (f) involves providing a feed map FMP, which provides the feed rate FDR at a given constant tool angle and a given chip thickness CPT.
[0038] Step (g) involves dividing the tool path TPT segment SGT into tool path TPT sub-segments SSG with a predefined segment length SGL. The segment SGT is divided into sub-segments SSG with equal tool path TPT lengths. When applying step (g), when dividing the tool path TPT into tool path TPT segments SGT, two different options can be alternately applied to determine the predefined sub-segment SSG length (these options are referred to as "ΔAGP<ACI,TTL" and "ΔFDR<FCI,TTL" in Figure 1 ): (i) The first option is carried out by the following steps: - Providing a sub-segment angle change increment ACI, - Determining the segment angle change SAC as the difference between the preset angular positions PAP at the end position EPT of the segment SGT, - Divide the segment SGT into sub-segments SSG, and distribute the tool angle change of segment SGT to the angle change portion of sub-segments SSG, such that each sub-segment SSG has a tool angle change portion lower than the sub-segment angle change increment ACI. When applying this option, preferably, the tool angle change of segment SGT is divided into angle change portions of sub-segments SSG with equal angle changes.
[0039] (ii) The second option is performed by following these steps: - Provides incremental FCI for segment feed rate changes. - Determine the difference between the segment feed rate change SFC and the feed rate FDR at the end position of segment SGT. - Divide the segment SGT into sub-segments SSG, and distribute the segment feed rate change (SFC) to the feed rate change portion of the sub-segments SSG, such that each sub-segment SSG has a feed rate change portion lower than the sub-segment angle change increment (FCI). When this option is applied, the tool angle change of segment SGT is divided into feed rate change portions of sub-segments SSG with equal feed rate changes.
[0040] Step (h) involves determining the angular position AGP at the end position EPT of segment SGT by interpolating ITP between the positions of the specified tool angle TAP. During step (h), it is assumed that the rate of change of angle along the toolpath TPT of segment SGT is linear.
[0041] Step (i) involves determining the feed rate FDR at the end position of segment SGT by assigning the corresponding preset local angular position PAP to the feed map FMP. During step (i), it is assumed that the linear feed rate FDR and the linear angular position AGP change to interpolate ITP between the EPT parameters at the corresponding end position of segment SGT along the toolpath TPT of segment SGT.
[0042] Step (j) involves determining the dynamic feed rate (DFR) and dynamic angular position change (DAP) based on the interpolation ITP between the EPT parameters of the toolpath TPT along the segment SGT at the corresponding segment SGT end position. During step (j), it is assumed that the linear angular position (AGP) changes to be used for interpolating the ITP between the parameters of the toolpath TPT along the segment SGT at the corresponding segment SGT end position.
[0043] The purpose of these methods is to ensure that the tool position changes continuously between preset angular positions as the tool moves along the toolpath TPT according to a feed calculation based on a specified chip thickness CPT.
[0044] As shown in step (c) or (f), the turning tool TTL can have a rhomboid insert INS for cutting the workpiece WPC material MAT. Other shapes are also possible, as described in the general description section.
[0045] The lathe MCH, as symbolized by the box in step (a), may include a processor CPU. This processor CPU may be designed and fabricated to perform the method according to the invention or one of its preferred embodiments.
[0046] Although the invention has been described in detail with reference to preferred embodiments, it should be understood that the invention is not limited to the disclosed examples, and that many additional modifications and variations can be made by those skilled in the art without departing from the scope of the invention.
[0047] Regardless of the usage of grammatical terms, all terms include masculine, feminine, and other parts of speech.
Claims
1. A method for machining a workpiece (WPC) using a B-axis lathe (MCH), wherein, The method involves continuously changing the angular position (AGP) of a turning tool (TTL), and the method includes the following steps: (a) Provide the original contour geometry (RCG) of the workpiece (WPC). (b) Provide the target profile geometry (TCG) for the workpiece (WPC). (c) Provide a predetermined chip thickness (CPT) as the target chip thickness (CPT) during processing. (d) Provide the tool path (TPT) of the turning tool (TTL) during machining of the target contour geometry (TCG). (e) Provide a preset angular position (PAP) of the turning tool (TTL) along the tool path (TPT), the preset angular position ensuring that the turning tool (TTL) can approach the workpiece (WPC) contour during machining (MCH), and the position of the specified tool angle (TAP) of the preset angular position (PAP) divides the tool path (TPT) into segments (SGT). The method is characterized by further comprising the following additional steps: (f) Provide a feed map (FMP) that provides a feed rate (FDR) at a given constant tool angle and a given chip thickness (CPT), wherein the feed rate (FDR) is determined by the rotational speed of the workpiece (WPC) and the rate at which the turning tool (TTL) advances along the workpiece (WPC). (g) Divide the toolpath (TPT) segment (SGT) into toolpath (TPT) sub-segments (SSG) with a predefined segment length (SGL). (h) Determine the angular position (AGP) at the end point (EPT) of the segment (SGT) by interpolating (ITP) between positions of specified tool angles (TAP). (i) The feed rate (FDR) at the end position of the segment (SGT) is determined by assigning the corresponding preset local angle position (PAP) to the feed map (FMP). (j) Determine the dynamic feed rate (DFR) and dynamic angular position change (DAP) based on the interpolation (ITP) between the parameters of the corresponding segment (SGT) end position (EPT) of the tool path (TPT) along the segment (SGT), and machine the workpiece (WPC) such that the tool position continuously changes between the preset angular positions as the tool moves along the tool path (TPT) according to the feed calculation based on the specified chip thickness (CPT).
2. The method for processing a workpiece according to claim 1, wherein, During step (h), it is assumed that the rate of change of angle along the toolpath (TPT) of the segment (SGT) is linear.
3. The method for processing a workpiece according to claim 1 or 2, wherein, During step (i), it is assumed that the linear feed rate (FDR) and the linear angular position (AGP) change to interpolate (ITP) between the corresponding segment (SGT) end point position (EPT) parameters along the segment (SGT) toolpath (TPT).
4. The method for processing a workpiece according to any one of the preceding claims, wherein, During step (j), it is assumed that the linear angular position (AGP) changes to be used for interpolation (ITP) between the corresponding segment (SGT) endpoint parameters along the segment (SGT) toolpath (TPT).
5. A method for processing a workpiece according to any one of the preceding claims, wherein, During step (g), when the toolpath (TPT) is segmented into toolpath (TPT) segments (SGT), a predefined sub-segment (SSG) length is provided through the following steps: - Provides sub-segment angle change increment (ACI). - Determine the segment angle change (SAC) as the difference between the preset angular position (PAP) of the segment (SGT) end point position (EPT). - Divide the segment (SGT) into sub-segments (SSG) and distribute the tool angle change of the segment (SGT) to the angle change portion of the sub-segment (SSG), such that each sub-segment (SSG) has a tool angle change portion that is less than the sub-segment angle change increment (ACI).
6. The method for processing a workpiece according to any one of claims 1 to 4, wherein, During step (g), when the toolpath (TPT) is segmented into toolpath (TPT) segments (SGT), a predefined sub-segment (SSG) length is provided through the following steps: - Provides segment feed rate change increment (FCI). - Determine the segment feed rate change (SFC) as the difference between the feed rate (FDR) at the end position of the segment (SGT). - Divide the segment (SGT) into sub-segments (SSG) and distribute the segment feed rate change (SFC) to the feed rate change portion of the sub-segment (SSG) such that each sub-segment (SSG) has a feed rate change portion that is lower than the sub-segment angle change increment (FCI).
7. A method for processing a workpiece according to any one of claims 5 or 6, wherein, The segment (SGT) is divided into sub-segments (SSG) with equal toolpath (TPT) lengths.
8. The method for processing a workpiece according to claim 5, wherein, The tool angle change of the segment (SGT) is divided into angle change portions of the sub-segments (SSG) with equal angle changes.
9. The method for processing a workpiece according to claim 6, wherein, The tool angle change of the segment (SGT) is divided into feed rate change portions of the sub-segments (SSG) with equal feed rate changes.
10. A method for processing a workpiece according to any one of the preceding claims, wherein, The turning tool (TTL) has a diamond-shaped insert (INS) for cutting the workpiece material (WPC) (MAT).
11. A B-axis lathe (MCH) including a processor (CPU) designed and configured to perform the method according to at least one of claims 1 to 10.