Cam Surface Research Articles

Vibro-acoustics based sound pressure minimization in a cam-follower system using micro-geometric modifications on minimizing the noise

The systems with inherent combined rolling-sliding contacts, such as cam-followers, gearboxes, and clutches, generate undesirable noise. It affects operator well-being, environmental acoustics, and component wear during operation. The sound produced due to interaction between the cam and the follower can be reduced by micro-geometric changes, i.e., profile modification of the cam surface while maintaining the macroscopic geometry of the system. This study aims to identify an optimal profile modification to the cam, using a vibro-acoustic relationship between the contact forces, sound pressure to minimize the sound pressure. The methodology utilizes a mathematical model of a cam-follower system to estimate the contact forces for different parametric values, and an equivalent finite element model to obtain vibro-acoustic transfer functions for various profile modifications. Sound pressure is predicted for each profile based on the obtained transfer functions, and contact forces. The optimal profile is then selected based on a comparative evaluation of the predicted sound pressure levels. The outcome of this study would lead to the development of quieter systems with combined rolling-sliding contact.

A novel design method of a nonlinear elastic mechanism for series elastic actuators

Series elastic actuators with increasing nonlinear stiffness(NlSEA) have promising applications in human-machine interactions for the existence of a nonlinear elastic mechanism that supplies inherent safety and can implement high torque resolution under low load and quick dynamic response under high load. In this study, a novel design method for a nonlinear elastic mechanism that can be applied in NlSEA is proposed. By combining the S-shaped cantilever beam and specialized cam surface, this study proposed an analytical approach to design a nonlinear elastic mechanism satisfying a given stiffening torque-deformation relationship. The geometric parameters constraints were discussed to support parameter determination. Two kinds of cases of nonlinear elastic mechanisms with increasing and constant stiffness characteristics were conducted to verify the effectiveness and generalizability of the proposed design method by simulations. Moreover, a nonlinear elastic mechanism with an increasing stiffness characteristic was designed and a prototype was fabricated. A torque-deformation verification experiment, regulation response experiments, and sinusoidal tracking experiments were conducted to verify the accuracy, response performance, and tracking performance of the prototype. The designed nonlinear elastic mechanism has a large torque-to-mass ratio in a compact and lightweight structure.

Magnetorheological variable stiffness and damping flexible joint with cam working surface for industrial robot

In order to improve the environmental adaptability and interaction stability of industrial robotic arms, a flexible joint with variable damping and stiffness based on magnetorheological (MR) technology was proposed. The mechanical models for variable stiffness and damping of MR flexible joint were established, and the relationship between cam surface and variable stiffness element was derived based on the energy method. Subsequently, the variation patterns of equivalent stiffness and damping of the prototype under different excitations were experimentally tested, and the test results show that its mechanical properties meet the design requirements. To further verify the performance of the MR flexible joint on the robotic arm, we setup a collision buffering test system and investigated the buffering performance of the system under different working conditions. The buffering test results indicate that when the current of variable stiffness element is 2.0 A, the peak collision acceleration of the system after installing the MR flexible joint decreases by about 40.19% compare with the rigid collision.

Scaling a Gas Phase Residual Lithium Conversion Process on Ni-Rich NMC Cathode Materials in Commercial Fluidized Bed Reactors

‘Residual lithium’, the LiOH and Li2CO3 surface contamination that is ubiquitous to Ni-rich NMC manufacturing, is a significant obstacle in the large-scale production and handling of high-nickel layered oxides. These hydroxide and carbonate surface phases influence reproducibility and shelf stability of the NMC powder and cause gelation and particle aggregation during electrode casting. There is ample evidence in the literature that atomic layer deposition (ALD) possesses a two-fold solution to this problem.1-3 First, reactive organometallic species such as trimethylaluminum (TMA) can convert insulating residual lithium to a Li-rich LixAlyO conducting layer. Customizable ALD layers can then be added to inhibit the re-formation of the carbonate layer and to deter negative side reactions of the CAM surface with the liquid electrolyte. While highly impactful, these studies have mostly been relegated to small, lab-scale demonstrations of <50 g. As such, there remains a need to enable this ALD-assisted-technology for high-throughput commercial applications.In this talk, we will explore the progression of a residual lithium conversion process from lab (10 – 1000 mL) to industrial-scale (10 L – 100 L) fluidized bed equipment and how scale and material-dependent parameters can impact performance. Using a commercial NMC 811 cathode as a case study, we first applied aluminum phosphate ALD coatings on a lab-scale fluidized bed reactor to examine the interfacial and electrochemical changes of the CAM material under various process conditions. ICP-OES measurements confirmed linear and reproducible deposition versus ALD cycle number between 200- 300°C. XPS analysis showed the ALD coated NMC 811 powder had an 80% reduction in Li2CO3 versus the pristine material and that a reduction persisted even after 10 days of storage in atmospheric conditions. At standard (0.5C/1C) cycling to 4.4V, AlPO4 coatings increased cycle life by 44% versus the uncoated powder. Under optimized conditions, the process was scaled first to 1 kg and finally to 10 kg in a pilot-scale reactor. In-situ mass spectrometry indicated that residual lithium conversion byproducts such as CO2 could be used to monitor reaction progress and optimize chemical usage efficiency. Fluidization aids including vibration and mechanical stirring were used to inhibit and break up powder agglomerates. ICP-OES and electrochemical cycling data confirmed reproducible deposition and cycle life benefits versus the small scale runs and pristine materials, demonstrating a pathway for these ALD-enhanced materials to transition from lab-scale demonstration to viable product. We will discuss strategies for continuing the scaling process to 100 kg batches for commercial applications.[1] M. Young et al., The Journal of Physical Chemistry C 2019 123 (39), 23783-23790[2] P. Darapaneni et al., ACS Applied Energy Materials 2022, 5, 8, 9870–9876[3] J. Li et al., Coatings 2022, 12(1), 84

On the application of spatial four-bar motion and axode generation for the design of a prosthetic canine knee joint

The novelty of this work is that for the first time, spatial four-bar linkage motion generation and axode generation models have been applied for the design of a joint to replicate natural canine knee motion. This canine knee design method incorporates spatial four-bar Revolute-Revolute-Spherical-Spherical linkage motion generation and axode generation models to ultimately produce the rolling cam surfaces needed to produce natural spatial canine knee motion. This work presents the latest findings from an ongoing study where a transfemoral prosthetic knee design method is being applied to produce concept prosthetic knee joints for canines that replicate natural spatial knee motion during treadmill gait. To date, this study has considered three canine subjects, ranging from ages 1.1 to 10 years and treadmill speeds ranging from 1.3 to 2.9 km/h.

IMPLEMENTING OF PHOTOREALISTIC SURFACE RENDERING IN CAM SIMULATION

In this paper, different approaches to visualize CAM simulation results are presented. Simulated machined surfaces can be rendered in a photorealistic manner taking into account real tool motions and vibrations measured during the machining process. The actual tool trajectories are used to derive the microrelief of machined surface that lead to different reflective properties to be used in the CAM surface rendering pipeline. Broaching and grinding were two machining processes to adopt this photorealistic visualization. First, the generic CAM simulation computed the triangulated representation of the in-process workpiece. Second, the triangles were enriched with the computed micro topography information that is used by the developed shader implementation during the visualization process.

Numerical and experimental study on flat roller/cam pair in a two-dimensional piston pump

The two-dimensional piston pump with flat roller/cam transmission mechanism enables high-speed operation, frequent load-carrying start-ups, and rotational direction changes, making it suitable for electro-hydrostatic actuators. This study investigates the rolling friction loss and starting torque characteristics of the friction pair under high-speed and high-load conditions. Numerical simulations show that the flat roller/cam friction pair is unsuitable for elastohydrodynamic lubrication when the roller surface hardness exceeds the cam surface. Experimental results reveal a friction coefficient of 0.0042 during load-carrying start at 1400 N, equivalent to 28 MPa pump load pressure, and 0.001 at 10000 rpm and 1400 N. The study highlights the high transmission efficiency of the designed mechanism, allowing load-carrying start-ups without relying on an oil film.

Influence of surface treatment on repair bond strength of CAD/CAM long-term provisional restorative materials: an in vitro study

BackgroundThe surface treatment to improve the repair bond strength may vary because CAD/CAM provisional restoration polymers exhibit a variety of microstructures. This study was conducted to evaluate the effect of surface treatments on the repairability of three different CAD/CAM polymers for long-term provisional restorations.MethodsThirty specimens from each provisional restorative materials (CAD-Temp, Everest C-Temp, and PEEK) were divided into three groups: C: surfaces received no treatment; SB: surfaces were airborne particle abraded with 50 μm aluminum oxide; SB-T: surfaces received the same conditions as group SB in addition to thermocycling before and after treatment. Primer and nanohybrid repair resin composite were applied to the prepared CAD /CAM surfaces. The shear bond strength and the mode of failure were assessed. ANOVA and Tukey’s significant difference tests were used to evaluate the data.ResultsThe SB group had significantly higher repair SBS values (p < .001) compared to the other groups (C and SB-T). Everest C-Temp significantly recorded the highest repair SBS (17.84 ± 0.19 MPa) in group SB, while the lowest repair SBS values (5.51 ± 1.14 MPa) for CAD-Temp were recorded in group C. PEEK significantly recorded the second highest repair SBS (15.96 ± 0.18) in the SB group.ConclusionsEverest C-Temp had the highest repair SBS after an airborne abrasion particle. Thermocycling had no significant effect on the repair SBS for PEEK. Everest C-Temp and PEEK are recommended as long-term durable provisional materials for clinical use.

Mathematical modeling on a novel manufacturing method for roller-gear cams using a whirl-machining process

The whirl-machining process is a precise, efficient, and promising machine process for manufacturing workpieces over the milling process. At the same time, the roller-gear cam has advantages over the other cam-follower system. However, the whirl-machining process has not been applied to manufacture the roller-gear cam. Therefore, this paper proposes a novel method for roller-gear cam manufacturing using a whirl-machining process. Mathematical modeling is described for generating the roller-gear cam, roller, and whirl-milling tool surface. A novel CNC machine and its coordinate system are proposed. Cutting simulations for obtaining the surface topologies and normal deviations are conducted. Globoidal cam with different cylindrical rollers, globoidal cam with a conical roller, and cylindrical cam with a conical roller are taken as case studies, and results are discussed. A virtual cutting simulation was conducted using VERICUT. Some machining examples are shown to verify the benefits of the proposed method in roller-gear cam manufacturing.

The Development of Tribology in Lubrication Systems of Industrial Applications: Now and future impact

Over the past 25 years, natural resources have been used up quickly, causing significant damage and contamination to the planet which is earth. Tribology, a new technology for keeping power and parts running, supported extremely fast and efficient coal and oil-powered machinery throughout history. Many different kinds of resource reserves, like those for power and parts, will be gone in a century. Revolutionary zero-emission and durability technologies are in high demand all over the world in order to create new, truly healthy and long-lasting lifestyles for humans and other living things in a symbiotic way. Tribology is expected to expand its technological innovation in order to support a new industrial trend and meet the requirements of the sector. At the moment, the primary factors influencing engine development are cost, performance, governmental requirements, and consumer requirements. In a few instances, the requirements are linked to tribology. For engines to last longer and be more reliable, tribology advancements that reduce friction and increase wear resistance will be crucial. The components under scrutiny are a part of the heavy-duty diesel engines’ valvetrain mechanism. The fuel injector places a lot of strain on the injection cam, making it one of the camshaft’s most problematic components. Lubrication plays a crucial role in avoiding cam failure caused by wear. The cam and roller contact, in any case, has shown to be one of the most provoking tribological plan challenges to handle. For lubricated contacts, the type and amount of wear are significantly influenced by the degree of separation between the surfaces. The term “specific film thickness” refers to this degree of separation and measures the degree to which asperities interact with one another in the lubricated contact. In order to predict lubrication regimes and, consequently, identify the injection cam’s likely wear zones, this paper focuses on measuring the oil film thickness in the cam-roller contact and other machine parts that follows. The results of the experiment (the observation of worn cam surfaces) are then confronted. In the near future, a multivariate analysis will be used to ascertain how the various parameters affect oil film thickness. The following stage will primarily focus on modeling injection cam wear, which will also include quantifying relationships between wear and a specific film thickness.

Design and application of a biconjugate closed-end cylindrical single-cam pair

A biconjugate closed-end cylindrical single-cam pair refer to a cylindrical cam pair that control two roller followers. Based on the theory of space conjugated surface and vector revolving, by analyzing the conjugation relation between two rollers and cam surfaces of a biconjugate closed-end cylindrical single-cam pair, the parameter equations of the moving path of the axis of the left and right rollers that envelope the cam surface are established. Taking the minimum clearance between the roller and cam surfaces as the optimization objective, the parameter equation was optimized by adjusting the coefficient of the parameter equations of the left and right rollers without changing the structural size of the cam pair, and the optimized equation can be directly used as the tool path of cam machining. Finally, the cam was machined by a 5-axis NC machining center, and the optimized effect was verified by measuring the clearance between the work face of the cam and the rollers after the assembly of the cam, swing rods, and other parts. The obtained results showed that the clearance between the work face of cam and rollers were significantly reduced after optimization, indicating that the optimization method of cam is reasonable.

Ленточное глубинное шлифование – прогрессивный вид механической обработки

he results of experimental work on abrasive-belt creep feed grinding of 20X13 steel and VT3-1 alloy are presented. The advantage of abrasive-belt creep-feed grinding, which allows significant increasing of the efficiency of work on a workpiece of machine parts, particularly having cam surfaces, such as steam and gas turbine blades, propeller blades, etc., is shown.

The CathPilot: A Novel Approach for Accurate Interventional Device Steering and Tracking

Accurate device navigation and control are significant challenges in various minimally invasive cardiovascular interventions. The long length of the devices used (e.g., catheters and guidewires), their high flexibility, and their engagement with the tortuous anatomy limit the accurate and reliable control and navigation of the device's tip. This article aims to design, develop, and assess a novel alternative solution that promises to overcome the major limitations of conventional devices. By utilizing an expandable cable-driven mechanism and a corresponding 3-D cam surface for cable length adjustment, we propose a fully manually operated system that can be navigated through the tortuous anatomy and then teleoperated to allow for accurate, reliable, and localized position control and tracking of the device. In this article, the methods of design, development, and verifications of this system are presented. The system's performance is assessed under different path tortuosity conditions and different opening diameters of the expandable frame. Our results indicate that the proposed system provides complete teleoperation of the device within the full reachable workspace of the mechanism and allows for positioning and tracking of the device with submillimeter accuracy irrespective of the tortuosity of the path and expansion size of the frame. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ex-vivo</i> phantom model experiments also show the device significantly outperforms conventional devices in terms of navigation time and success rate. The CathPilot allows for direct manipulation, accurate positioning, and tracking of the device tip relative to the anatomy, promising to overcome some of the major limitations of conventional interventional devices.

Automated 3D Analysis of Clinical Magnetic Resonance Images Demonstrates Significant Reductions in Cam Morphology Following Arthroscopic Intervention in Contrast to Physiotherapy

PurposeTo obtain automated measurements of cam volume, surface area, and height from baseline (preintervention) and 12-month magnetic resonance (MR) images acquired from male and female patients allocated to physiotherapy (PT) or arthroscopic surgery (AS) management for femoroacetabular impingement (FAI) in the Australian FASHIoN trial.MethodsAn automated segmentation pipeline (CamMorph) was used to obtain cam morphology data from three-dimensional (3D) MR hip examinations in FAI patients classified with mild, moderate, or major cam volumes. Pairwise comparisons between baseline and 12-month cam volume, surface area, and height data were performed within the PT and AS patient groups using paired t-tests or Wilcoxon signed-rank tests.ResultsA total of 43 patients were included with 15 PT patients (9 males, 6 females) and 28 AS patients (18 males, 10 females) for premanagement and postmanagement cam morphology assessments. Within the PT male and female patient groups, there were no significant differences between baseline and 12-month mean cam volume (male: 1269 vs 1288 mm3, t[16] = −0.39; female: 545 vs 550 mm,3t[10] = −0.78), surface area (male: 1525 vs 1491 mm2, t[16] = 0.92; female: 885 vs 925 mm,2t[10] = −0.78), maximum height (male: 4.36 vs 4.32 mm, t[16] = 0.34; female: 3.05 vs 2.96 mm, t[10] = 1.05) and average height (male: 2.18 vs 2.18 mm, t[16] = 0.22; female: 1.4 vs 1.43 mm, t[10] = −0.38). In contrast, within the AS male and female patient groups, there were significant differences between baseline and 12-month cam volume (male: 1343 vs 718 mm3, W = 0.0; female: 499 vs 240 mm3, t[18] = 2.89), surface area (male: 1520 vs 1031 mm2, t(34) = 6.48; female: 782 vs 483 mm2, t(18) = 3.02), maximum-height (male: 4.3 vs 3.42 mm, W = 13.5; female: 2.85 vs 2.24 mm, t(18) = 3.04) and average height (male: 2.17 vs 1.52 mm, W = 3.0; female: 1.4 vs 0.94 mm, W = 3.0). In AS patients, 3D bone models provided good visualization of cam bone mass removal postostectomy.ConclusionsAutomated measurement of cam morphology from baseline (preintervention) and 12-month MR images demonstrated that the cam volume, surface area, maximum-height, and average height were significantly smaller in AS patients following ostectomy, whereas there were no significant differences in these cam measures in PT patients from the Australian FASHIoN study.Level of EvidenceLevel II, cohort study.

P‐138: High Torque Hinge for Large Size Foldable Device

In order to expand the mobile foldable technology to large size IT device, we have developed a folding hinge having high torque value. It has stress‐free folding characteristics by virtual axis structure and compact dimension by the parallel arrangement of a folding part and a torque part. Therefore, we can make a large size foldable device which is slim and narrow bezel. It has the torque value of 14 kgf·cm on device and free‐stop function. By the enlargement of friction area by the change of CAM concept and the structural optimization we can reduce abrasion of hinge CAM surface, and the torque reduction by 70k folding lifetime test is less than 20% of its initial value. It is very important progress in the foldable technology.

Research on Machining Error Analysis and Traceability Method of Globoidal Indexing Cam Profile

The profile of the globoidal indexing cam is a spatially undevelopable surface. It needs a special computer numerical control (CNC) machine tool to finish batch production, and its machining quality will be affected by the motion error of each part of the machine tool and the clamped positioning error of the workpiece. Firstly, the mathematical model of the error of the machine tool for machining the globoidal cam surface is derived, and the influence of the error of the machine tool for machining the globoidal cam surface is given. Secondly, an error tracking method for globoidal cam profile machining error based on error sensitivity coefficient grouping is proposed, which improves the data processing speed and the accuracy of the tracking results. Finally, the error analysis and traceability method of the globoidal cam is verified by experiments, and the error traceability results are fed back to the processing link. The machining quality of globoidal cam is improved by the error compensation, which provides the key technology for the integration of the design, manufacture, and measurement of the globoidal cam.

Study on the Compressive Stress Retention in Quenched Cam of 100Cr6 Steel Based on Coupled Thermomechanical and Metallurgical Modeling.

The assembled camshaft has obvious advantages in material optimization and flexible manufacturing. As the most important surface modification technique, the heat treatment process is utilized in this work to promote the desired compressive residual stress on the near-surface of the 100Cr6 steel assembled cam. The Johnson-Mehl-Avrami equation and Koistinen-Marbuger law are integrated into the ABAQUS software via user subroutines to simulate the evolution of diffusional transformation and diffusionless transformation, respectively. The linear mixture law is used for describing the coupled thermomechanical and metallurgical behaviors in the quenching of steel cam. The influences of various quenchants and the probable maximum phase volume fractions on surface residual stress or hardness are analyzed. Results show that a greater amount of martensite volume fraction and a slower martensitic transformation rate are beneficial for the compressive stress retention. Compared with the conventional quenching oil, the fast oil quenched cam surface has higher final compressive stress and hardness.

Analysis of the combination of the slider-crank and cam mechanism to drive the automatic bandsaw blade grinder

A slide crank and cam mechanism can be combined and used to drive a bandsaw blade grinder. The movement of these mechanisms must ensure a harmonious combination to avoid the impacts of a collision and dynamic load that appears on the cam and roller surfaces. The technical parameters can be determined by methods of geometry, or 3D simulation, or analytical methods. In order to flexibly design the cam and slide crank mechanism, this study uses the analytic method. By setting up mathematical formulas and applying Mathcad software, it allows to quickly determine and change the initial parameters of the mechanisms, evaluates their changes to the stroke and structural profile. Simultaneously, the graphs of the stroke, velocity, and acceleration of the cam mechanism allow the designer to evaluate and select suitable parameters.

Simulation Analysis of Cam Wear in Shedding Mechanism of Loom

Aiming at the serious wear of the cam surface in the shedding mechanism of the loom weaving, which is likely to cause uneven movement of the heald frame, this paper proposes to add a layer of copper-plated carbon fiber composite material to the cam surface to improve the cam wear during the operation of the shedding mechanism. In finite element ABAQUS®, the cam is modeled, material properties and boundary loads are set, and ALE adaptive mesh technology and Umeshmotion subroutine are also used for wear analysis. The simulation results show that under the same conditions, the wear between the cam and the roller with a copper-plated carbon fiber layer is much smaller than the wear between the pure metal cam and the roller.

Studying the ophthalmic toxicity potential of developed ketoconazole loaded nanoemulsion in situ gel formulation for ophthalmic administration

Ocular fungal infections are one of the essential reasons for vision loss, especially in developing countries for tropical regions. Ketoconazole (KZ), a broad-spectrum antifungal drug, is a lipophilic compound and practically insoluble in water. Since topical ophthalmic drug delivery confronts low bioavailability, an in situ gel formulation is designed to improve the residence time and consequently the bioavailability. Safety of the developed formulation as a carrier for ophthalmic drug delivery was measured using three different methods: MTT assay for measuring cell viability in which the human retinal pigmentation epithelial cells (RPE) were used, HET-CAM as a borderline method between in vivo and in vitro techniques for investigating the irritation potential of the chosen formulation which was done by adding formulation directly on the CAM surface and visually monitoring the vessels in terms of irritation reactions, and finally the modified Draize test for evaluating tolerability of the selected formulation on eyes. According to our results from the MTT test, cell viability for KZ-NE in situ gel formulation at 0.1% concentration was acceptable. The results obtained from the HET-CAM investigation didn’t show any sign of vessel injury on the CAM surface for prepared formulation. Additionally, during 24 hours, the developed formulation was tolerable by rabbit eyes. Regarding our results, KZ-NE in situ gel formulation was non-irritant and non-toxic and can be well-tolerated and presented as an applicable vehicle for ophthalmic delivery of the anti-fungal drug.