Linear Axis Research Articles

Optimization of a Redundant Freedom Machining Toolpath for Scroll Profile Machining

The scroll disc is a critical functional component of the scroll compression mechanism, and its machining precision and quality directly impact the performance and longevity of the compressor. Current machining methods for scroll profiles face challenges in simultaneously achieving wide applicability, high precision, and high efficiency. This paper addresses issues related to unsmooth toolpaths of machine tool axes and high acceleration in the rotary axis during redundant degrees of freedom scroll profile machining. This paper proposes a toolpath optimization method for redundant axes, with optimization objectives focused on reducing the counts of directional changes in the linear axes and smoothing the trajectories of all axes. Experimental results demonstrate that the proposed method offers higher machining efficiency compared to traditional polar coordinate machining.

The Analysis and Compensation Experiment of Linear Feed Axis Positioning Error Based on Matrix Operation

The positioning accuracy of the linear feed axis is a key factor affecting the machining accuracy of CNC machine tools. The generation process of the positioning error of the linear feed axis is expounded. The Z axis of the vertical linear feed axis of the machining center is the research object, the positioning error analytical matrix is established, and the positioning error calculation of the Z axis of the vertical linear feed axis is completed based on the principle of solving the inhomogeneous linear equation. The positioning error detection of the vertical linear feed axis Z axis of the CNC machining center is carried out. Based on the characteristics of the error detection data, an error compensation model is constructed. , the variance of the positioning error detection point after compensation is reduced to 1.562, which meets the needs of precision machining.

Universal production of anisotropic bilayer WSe2 nanoscrolls for high-performance photodetector

Abstract Transition metal dichalcogenide nanoscrolls (NSs) exhibit unique optoelectronic properties due to their spiral tubular structures. In this study, we successfully fabricated WSe2 NSs with various morphologies, illustrating the evolution from planar to NS via an internal strain-driven rolling process. The anisotropic optical properties of the NSs were systematically analyzed by angle-resolve polarized Raman spectroscopy. For NSs with different rollup angles, the strain distribution is manifested by the variation of Raman intensity on the linear axis. In addition, the on/off ratio and detectivity of device based on bilayer NS reach 5.3 × 104 and 2.63 × 109 Jones, caused by the ultralow dark photocurrent. In summary, our study demonstrates a universal method for producing polymorphic products, demonstrating that bilayer WSe2 NSs hold significant potential as a platform for fundamental research and technological applications.

Research on positioning accuracy of the swivel head of milling and turning complex machining center

Abstract This article focuses on the swivel head of a milling-turning complex machining center and establishes a geometric error model between the rotary axes based on the multi-body system theory and the homogeneous coordinate transformation method. The double ball bar (DBB) is used to identify the geometric errors of the machine tool swivel head position-independent by measuring circular trajectories. The impact of PIGEs on the measurement trajectory is simulated. The swivel head is rotated at four angles (B0°, B45°, B90°, B-15°), and the laser tracker is used to analyze and study the linear axis straightness, perpendicularity, and the center coordinates and plane errors of the swivel head movement along the XZ plane. A swivel head rotation accuracy test fixture is designed to correct the positioning accuracy of a swivel head with a 45° inclination of the rotation axis. The research results show that the fluctuation of the center plane degree of freedom of the swivel head moving along the XZ plane is small, and the maximum value is 0.0086mm. Under the 45° angle posture of the swivel head, both the center coordinate error value and the plane error value are the largest. The simulation results of the swivel head position error are fairly consistent with the center coordinate error of the swivel head plane movement. A backward tilt displacement of 0.01mm~0.015mm of the machine column during assembly can reduce the influence of the weight of the swivel head on the perpendicularity and straightness of the vertical reciprocating motion, and adding auxiliary support near the base of the swivel head zero position can reduce machine straightness error.

Validating real time compensation: A thermal test piece for 5-axis machine tools to separate thermal errors in Z-direction

The accuracy of 5-axis machine tools is a key factor to manufacture multi-axes machined workpieces. However, thermal deformations of the machine structure often cause significant deviations at the tool centre point. To evaluate the impact of thermal errors on the accuracy of 5-axis machine tools under machining conditions, suitable thermal test pieces are required. Therefore, this paper introduces a 5-axis thermal test piece which is based on the thermal test piece for rotary axes being part of the standard ISO 10791-10:2022. The new thermal test piece identifies ten instead of five thermal errors during eight time steps. The additional features enable an error separation of the table-related thermal error and the thermal error pointing consistently in Z-direction. This error separation is especially important to analyse the accuracy of five-axis milling operations. In total, the developed 5-axis thermal test piece analyses five location, two length and three orientation errors without requiring a kinematic model of the machine tool. The conducted experiments comprise thermal load cases without and with metal working fluid and show a clear agreement between the thermal location errors and the dominant thermal orientation errors of the thermal test piece and an on-machine measurement cycle. On the other hand, the analysed thermal length errors of the thermal test piece indicate a clear effect of the thermal material expansion compared to the thermal positioning errors of the analysed machine tool. Furthermore, the analysed thermal load cases of the linear and rotary axes conducted without and with metal working fluid result in a different thermal behaviour of the machine tool depending on the use of metal working fluid. Finally, the developed 5-axis thermal test piece is used to evaluate a thermally compensated 5-axis machine tool under machining conditions for thermal load cases without and with metal working fluid. The self-learning thermal error compensation reduces the mean of the thermal location errors at the thermal test piece by up to 71%.

CNC linear axis condition-based monitoring: a statistics-based framework to establish a baseline dataset and case study

CNC linear axis condition-based monitoring: a statistics-based framework to establish a baseline dataset and case study

Portable 5-DOF measurement system using a parallel beam generation method for linear axis detection.

Geometric error detection is crucial for evaluating the accuracy of the linear axis. However, the practicality of traditional dual-beam detection systems is limited by the parallelism of beams. This study proposes a portable 5-DOF measurement system using a novel parallel beam generation method. Two orthogonal corner cube retroreflectors (CCRs) and a beam splitter (BS) are utilized to achieve two measuring beams with excellent parallelism, which is determined solely by the CCR. The theoretical parallelism of beams is analyzed and experimentally verified. Two position sensitive detectors (PSDs) and one autocollimator are used to measure two straightness errors and three angular errors, and the detection deviations are modelled and compensated. The experiment proves that dual beam that are generated on the basis of the above structure could achieve a parallelism of 5.9'' without careful adjustment. The designed 5-DOF measurement system has a straightness measurement range of ± 400 µm and an angle measurement range of ± 300''. The repeatability of the system is 2.20 µm for straightness errors, 1.58'' for yaw error, 1.82'' for pitch error and 5.04'' for roll error detection. The designed 5-DOF measurement system has the advantages of a simple structure and stable accuracy and is very practical in measuring the geometric errors of machine tools.

Digital-twin-driven intelligent tracking error compensation of ultra-precision machining

In ultra-precision machining (UPM), linear axis tracking affects contour accuracy and final machining quality. Traditional error modeling is complicated by the identification of numerous unknown parameters linked to nonlinear characteristics in the linear feed axes. To fill this gap, this study proposed a digital-twin-driven framework integrating the developed G-code interpreter and the deep learning model to achieve real-time tracking error compensation for UPM. To enhance the prediction accuracy of the tracking error of each axis of UPM machines, Bayesian hyperparameter optimization and feature importance analysis were conducted in the proposed TCN-BiLSTM model using high-quality training datasets from well-designed experiments. Ultimately, validation of the proposed system on a three-axis ultra-precision milling machine demonstrated its excellent performance. The experimental results showed that the optimized TCN-BiLSTM model exhibited an excellent capacity to predict the tracking error of the X-axis and Y-axis with minimal mean absolute error values of 0.000009 and 0.000023, respectively. Implementing the customized application reduced X-axis and Y-axis tracking errors by approximately 45–75% and 40–70%, respectively. This study first validates the feasibility of deep learning to improve accuracy in the UPM field, which will provide significant insight into speeding up the digitalization and intellectualization of the UPM scenario.

Distinct tumor microbiome and metabolomic profiles to inform responses of patients with esophageal cancer to neoadjuvant chemoradiotherapy and immunotherapy.

4084 Background: Preclinical and clinical data indicate that neoadjuvant chemoradiotherapy (CRT) may prime an anti-tumor immunological response in esophageal cancer driven by intratumoral CD8+ T cells. However, responses to neoadjuvant therapy can vary widely across patients. The microbiome, a novel and potentially modifiable biomarker of immunotherapy response, may inform neoadjuvant response. Methods: Fecal and tumor samples were collected from patients with stage II-III resectable distal esophageal or gastroesophageal junction carcinoma treated with neoadjuvant immunotherapy followed by chemoradiotherapy (CRT) and immunotherapy (IO). Patients on arm A (n=15) received 2 cycles of induction with nivolumab plus 3 additional cycles with CRT. Patients on arm B (n=10) received nivolumab and relatlimab on a similar induction schedule, but concurrent IO and CRT resulted in immune related adverse events and a protocol amendment to CRT (NCT03044613). We examined fecal (n=19) and tumor (n=12) patient samples across both arms using 16S rRNA amplicon sequencing and high-resolution taxonomic assignment. Additionally, fecal samples were analyzed using an untargeted panel (General Metabolics) and pathway analysis was performed using Metaboanalyst (v6.0). Results: The fecal microbiome of patients with pathological complete response (pCR) grouped in distinct clusters compared to patients without pathological complete response (non-pCR) using Bray-Curtis (p < 0.001). Patients with >10% and <10% residual tumor grouped similarly but were significantly different from patients with 0% residual tumor (p < 0.001). On a linear discriminant axis, the top 10 abundant bacteria were significantly increased in pCR compared to non-pCR (p < 0.001). After FDR correction, six bacteria had significantly differing abundances. Bacteroides finegoldii, Paraprevotella clara, Ruminococcus callidus, and Roseburis inulinivorans were significantly enriched in pCR patients. Clostridiales and Bacteroides were significantly enriched in non-pCR patients. Fecal metabolomic analysis demonstrated six significant metabolites: in non-pCR, ropinirole, valine, phenylalanine, and isoleucine were enriched; in pCR, C16cer and D-urobilinogen were enriched (p < 0.05). Patients with improved neoadjuvant response had significantly higher abundances of Bacteroides and corresponding C16cer levels. Pathway analysis revealed significant involvement in aminoacyl-tRNA biosynthesis and sphingolipid metabolism. Conclusions: Patients with complete responses to combined CRT and IO for operable esophageal cancer had distinct fecal microbiome profiles as well as metabolomic pathways. These results may be useful to further characterize and predict patients who have improved responses to neoadjuvant therapy and serve as a basis for therapeutic intervention.

Spinning and corkscrewing of oceanic macroplankton revealed through in situ imaging.

Helical motion is prevalent in nature and has been shown to confer stability and efficiency in microorganisms. However, the mechanics of helical locomotion in larger organisms (>1 centimeter) remain unknown. In the open ocean, we observed the chain forming salp, Iasis cylindrica, swimming in helices. Three-dimensional imaging showed that helicity derives from torque production by zooids oriented at an oblique orientation relative to the chain axis. Colonies can spin both clockwise and counterclockwise and longer chains (>10 zooids) transition from spinning around a linear axis to a helical swimming path. Propulsive jets are non-interacting and directed at a small angle relative to the axis of motion, thus maximizing thrust while minimizing destructive interactions. Our integrated approach reveals the biomechanical advantages of distributed propulsion and macroscale helical movement.

Geometric Error-Based Multi-Source Error Identification and Compensation Strategy for Five-Axis Side Milling

Based on a multi-source error model, this paper discusses the principle of error element identification and uses the mirror bias method to compensate the geometric errors of a process system. Firstly, a nine-line measurement method to determine the geometric error of the linear feed axes of machine tools is introduced, and the geometric error identification model based on the “nine-line method” is established. Then, using a ballbar mounted in the axial, tangential, and radial directions of the machine, the geometric error elements of the rotation axis are identified by three simple measurements in each direction. Subsequently, for the more common flat vise clamping workpiece in actual production, the workpiece position error is identified by using the traditional process of dimensional chain, and the workpiece attitude error is identified by fitting the angle between the positioning plane and the horizontal plane by the least squares method. Finally, based on the tool position points and tool axis vectors obtained from the multi-source error model, the error compensation value is solved using inverse machine tool kinematics to offset the machining error by mirroring the error value of the same size, and based on the “S-shaped specimen” to compensate the processing experiments, after compensation, the processing error is reduced by 30~45%, verifying the effectiveness of the compensation method.

Improving Machined Accuracy Under a Constant Feed Speed Vector at the End-Milling Point by Estimating Machining Force in Tool Approach

A five-axis machining center (5MC) is capable of synchronous control, which makes it a feasible tool for quickly and accurately machining complicated three-dimensional surfaces, such as propellers and hypoid gears. Recently, the necessity of improving both the machined shape accuracy and the machined surface roughness of free-form surfaces is growing. Therefore, in our previous study, we aimed to maintain the feed speed vector at the end-milling point by controlling two linear axes and a rotary axis of the 5MC to improve the quality of the machined surface. Additionally, we developed a method for maintaining the feed speed vector at the end-milling point by controlling the three axes of the 5MC to reduce the shape error of the machined workpieces (referred to as the shape error herein), considering the approach path of the tool determined via calculation. However, a high machining force at the start of the workpiece cutting was observed and the factor contributing to this phenomenon was not determined, although this phenomenon leads to a shape error to a certain degree according to the machining condition. In this study, the main objective is to suggest a method to reduce the machining force at the start of the workpiece cutting and shape error. Hence, we develop a theoretical method to estimate the machining force by using an instantaneous cutting force model, which considers the synchronized motion of two linear axes and a rotary axis of the 5MC. Subsequently, we determine the most suitable approach path of the tool considering the prediction of the machining force. The results of this study indicate that the machining force can be estimated by applying an instantaneous cutting force using the feed per tooth and machining angle, and that both a high machining force at the start of the workpiece cutting and shape error reduction can be realized by using the proposed approach path of the tool.

Comprehensive health assessment of faulty and repaired linear axis components through multi-sensor monitoring

Comprehensive health assessment of faulty and repaired linear axis components through multi-sensor monitoring

An approach for crucial geometric error analysis and accuracy enhancement of gantry milling machines based on generalized correlation sensitivity

Geometric errors in gantry milling machines with long-span beams and large travel can seriously degrade workpiece accuracy. Sensitivity analysis and compensation of geometric errors with coupling and fluctuation can significantly improve the machining performance of machine tools. An accuracy enhancement approach for gantry milling machines is proposed in this paper. Firstly, the geometry error analytic fluctuation eigenfunctions are established by using the high-order Fourier series fitting. Secondly, a non-linear generalized correlation analysis model is proposed to identify the crucial errors that significantly affect the machining accuracy. Thirdly, the motion commands compensated for geometric errors are calculated. Specifically, compared to traditional inverse kinematics, the proposed error compensation process is simple and suitable for most machine tools with orthogonal linear axes. Finally, comparative cutting experiments are performed. The accuracy of the test piece is improved by approximately 34.7 % with error compensation. The effectiveness of the proposed method is validated.

Efficient Method for Identifying Key Errors Based on 21-Geometric-Error Measurement of Three Linear Axes of Machine Tools

Key errors of machine tools have a significant impact on their accuracy, however accurately and quickly measuring the geometric errors of machine tools is essential for key error identification. Fortunately, a quick and direct laser measurement method and system for 21 geometric errors of three linear axes of machine tools were proposed previously, which enables the measurement of all 21 geometric errors via a one-step installation and a three-step automated measurement process. Based on this, to efficiently identify the key error factors, this paper first utilizes the 21 geometric errors obtained from the proposed measurement system to evaluate the contribution of each error to the volumetric errors of machine tools, leading to the building of a 21-geometric-error sensitivity analysis model. Then, experiments are carried out on the vertical machining tool TH5656, and all 21 geometric errors are obtained in 5 min. After this, the volumetric error distribution in the machining workspace is mapped according to the relationship between the geometric errors and the machining errors, and the key error factors affecting the manufacturing and machining accuracy of the TH5656 are ultimately determined. Thus, this new method provides a way to quickly identify key errors of the three linear axes of machine tools, and offers guidance for the machine tool configuration design, machining technology determination, and geometric error compensation.

Development of a universal, machine tool independent dynamometer for accurate cutting force estimation in milling

When integrating a dynamometer into a machining system, it is necessary to identify the dynamic relationship between the effective input forces and the measured output signals (i.e., its transmissibility) through dedicated experimental modal analysis. Subsequently, a filter can be derived and applied to reconstruct the effective input forces from the measured signals. Unfortunately this identification phase can be complex, posing challenges to the device’s applicability in both laboratory and industrial conditions. Here this challenge is addressed by introducing a novel dynamometer concept based on both load cells and accelerometers, along with a Universal Inverse Filter. Notably, this filter is independent of the dynamic behavior of the mechanical system where the device is installed. A single calibration suffices, ideally conducted by the device manufacturer or by an expert, allowing the dynamometer’s integration by a non-expert user into any machining system without the need for repeating the identification phase and the filter generation. Furthermore, this new concept offers another significant advantage: it attenuates all inertial disturbances affecting the measured signals, including those arising from the cutting process and those originating from exogenous sources such as spindle rotation, linear axes’ movements, and other vibrations propagating through the machine tool structure. To illustrate, a simplified model is introduced initially, followed by an overview of the novel dynamometer design, innovative identification phase, and filter construction algorithm. The outstanding performance of the novel (non-parametric) Universal Inverse Filter – about 5 kHz of usable frequency bandwidth along direct directions and 4.5 kHz along cross dir. – was experimentally assessed through modal analysis and actual cutting tests, compared against state of the art filters. The efficacy of the new filter, which is even simpler than its predecessors, was successfully demonstrated for both commercial and taylor-made dynamometers, thus showing its great versatility.

Linear Axis Guide Rail Misalignment Detection and Localization Using a Novel Signal Segmentation Analysis Technique

Maintenance of the linear axis and its components such as the linear guide can be significantly costly due to the difficult nature of the repair procedure and the downtime the machine exhibits while being repaired. This is a decision that must be made carefully and with proper justification. Therefore, it is crucial that the condition-based monitoring (CBM) system in the machine can detect and localize faults in the linear axis. The presented paper proposes a novel vibration signal segmentation analysis technique that detects and localizes misalignment in the linear guide rail, which is considered a leading root-cause failure fault. The results demonstrated that the usability of time domain features such as RMS was doubled by applying segmentation analysis. Also, evaluating both stroke directions aided in the localization of the misalignment. Overall, the practical value of the proposed technique is to function as both a localization and repair verification tool when performing linear axis maintenance.

High-precision servo control design and optimization for dicing semiconductor wafer

The dicing of semiconductor wafers is an essential component for fabricating electronic circuits. A servo control approach with high-precision and stability was designed to enhance the positioning accuracy and stability for dicing semiconductor wafers. The principal control and dicing processes were studied. The High Definition closed-loop control algorithm was designed, and the control parameters were optimized. The control performance was enhanced using the PID + Feedforward + NOTCH filter control algorithm. The error detection of linear and rotation axes was designed to compensate servo axis errors by using the laser interferometer and control card. After error compensation, the positioning accuracy and repeatability of the Y-axis were 2.031 μm and 1.889 μm. That of the C-axis were 0.00423°, and 0.00347°. The dicing experiment revealed the maximum chipping width was <10 μm and the dicing channel width was <42 μm. The designed servo control system ensured the high-precision and stable dicing of semiconductor chips.

Kinematics of the Reykjanes Ridge: Influence of the Iceland Hotspot on Plate Boundary Evolution

AbstractThe slow spreading Reykjanes Ridge overlies the Iceland hotspot and has undergone well ordered changes in crustal segmentation. Previous studies have attributed these changes to varying mantle plume thermal effects, rendering the lithosphere ductile or brittle. Here we use seafloor spreading magnetic anomalies to show that crustal accretion has been focused throughout its spreading history and to determine the detailed evolution of Reykjanes Ridge segments. By ∼53 Ma, organized spreading had developed on an orthogonally spreading linear axis following continental breakup. After a plate motion change at ∼38 Ma, orthogonally spreading offset ridge segments formed by ridge propagation forming varying length fracture zones. From then to the present, the offset segments diachronously migrated back to the original linear geometry from north to south replacing orthogonal with oblique spreading as the axis became linear again. Fracture zones were not terminated, however, simply by reducing segment offsets even to zero. Their termination involved the axial propagation of buoyant upwelling instabilities across the discontinuities, correspondingly extending V‐shaped crustal ridges southward. This evolution was guided by a persistent linear deep damp mantle melting interval maintained by the episodic propagation of buoyant upwelling instabilities. Our study indicates that at slow spreading ridges, where buoyant upwelling instabilities govern crustal segmentation, spatial gradients in mantle melting properties may direct the behavior of the instabilities. Where ridges overlie regional hotspot gradients in mantle melting, buoyant instabilities may propagate systematically, and plate boundary evolution may follow an organized pattern.

Remotely Sensed and Field Data for Geomorphological Analysis of Water Springs: A Case Study of Ain Maarrouf

Tabular Middle Atlas of Morocco holds the main water reservoir that serves many cities across Morocco. Dolomite and limestone are the most dominant geologic formations in this region in which water resources are contained. The recent studies conducted to evaluate the quality of this water suggest that it is very vulnerable to pollutants resulting from both anthropogenic and natural phenomenon. High and very high-resolution satellite imagery have been used in an attempt to gain a better understanding of this karstic system and suggest a strategy for its protection in order to reduce the impact of these phenomenon. Based on the surface reflectance of land cover benchmarks, the karstic system has been horizontally delineated, as well as regions with intense human activities. Using band combination in the portion of the infrared, shortwave infrared, and visible parts of the electromagnetic spectrum, we identified bare lands which have been interpreted as carbonate rocks, clay minerals, uncultivated fields, basalts rocks, and built-up areas. Other classes such as water and vegetation have been identified. Carbonate rocks have been identified as areas with a high rate of water infiltration through their fracture system. Using a Sobel operator filter, these fractures have been mapped and their results have revealed new and existing faults in two major fracture directions, NE-SW and NW-SE, where NE-SW is the preferable pathway for surface water infiltration towards the groundwater reservoir, while the NW-SE direction drains groundwater from the Cause to the basin of Saiss. Over time, the infiltration of surface water through fractures has contributed to a gradual erosion of the carbonate rocks, which in turn developed karst landforms. This karst system is vulnerable due to the flow of pollutants in areas with shallow sinkholes. Using GDEM imagery, we extracted karst depressions, and their analysis shows that they are distributed along the fracture system and many of them were located on curvilinear or linear axes along the NE-SW fracture direction. We found also dolines scattered in areas with a high intensity of fractures. This distribution has been validated by both on-the-ground measurements and very high-resolution satellite images, and depressions of different forms and shapes dominated by dolines, poljes, lapiez, and avens have been identified. We also found many water springs with a highly important water output, such as the Ain Maarrouf water spring. The aim of this study is to enhance the understanding of the hydrogeological system of TMA, to improve the existence of the fracture database in the Cause of Agourai, and to establish a new morpho-structural picture of the Ain Maarrouf water spring.