Movable Teeth Research Articles

Study on Relative Velocity of Moving Disk for Novel HTS Movable Tooth Motor

Study on Relative Velocity of Moving Disk for Novel HTS Movable Tooth Motor

Fabrication and manipulation for key elements of magnetic-driven speed-reduction micro-motor

The motion of magnetic-driven micro motor is controlled by external magnetic field, does not need any fuel which has good biocompatibility. However, its driving torque needs to be further improved. For it, a magnetic-driven micro-motor with speed-reduction function is proposed. The main elements for the micro-motor includes wave generator, central ring, and movable tooth frame which had to be fabricated with Electron beam lithography and vacuum evaporation coating technology. So, related processing parameters should be optimized to obtain high quality elements of the micro-motor. Here, a magnetic-driven micro-motor with speed-reduction function is proposed. Fabrication and manipulation techniques of the main elements for the micro-motor, such as wave generator, central ring, and movable tooth frame, are studied. Electron beam lithography, electron microscope, and atomic force microscopy (AFM) are applied to optimize the parameters of electron beam lithography. The optimized photolithography parameters are obtained, by which the micro movable tooth frame is successfully developed, and the photoresist molds of the wave generator and central ring is produced. Using vacuum evaporation coating technology, effect of evaporation rate on the quality of micro-parts is studied. The optimized evaporation rate is obtained, by which the nickel-based wave generator and copper-based center ring are successfully developed. The nickel-based wave generator and copper-based central ring are effectively peeled off from the substrate by ultrasonic oscillation technique. The effective manipulation of the wave generator and central ring is accomplished by AFM and piezoelectric-driven micro-probe.

A novel harmonic movable tooth drive with almost surface contact conjugate tooth profiles: Parametric design, modification and analysis

This paper focuses on a novel harmonic movable tooth drive as an alternative of currently used harmonic gear drives. Different from the harmonic gear drives, the novel drive removes small module teeth from thin-walled flexible rim, instead, adopts several rigid movable teeth with logarithmic spiral tooth profile. Such tooth geometry makes almost surface contact possible under load condition, in comparison with the conventional involute tooth profile creating a linear contact. Aiming at the issue of cusp meshing between movable tooth and ring gear during the meshing process, this paper proposes a modification design method for the conjugate tooth profiles. First, the radial motion law of movable tooth is modified, in order to avoid rigid impacts at the exchange point of the rise travel and return travel. Then, the tooth profile of ring gear is generated by the envelope of the modified profile of movable tooth. Based on the formulated modification scheme, the equations of the conjugate tooth profiles are derived, and the influences of spiral angle and modification parameters on the meshing characteristics are systematically investigated. Finally, the wave generator cam profile and pivoted segment profile are established considering the strength consistency. The outcomes can provide significance guidance for the parametric design and optimization of this novel drive.

Oil-Sealing Performance Evaluation of Labyrinth Seal Using Combined Finite Element Analysis and Computational Fluid Dynamics

Mechanical seals, such as labyrinth seals, are typically installed at the turbine outlets to prevent oil leakage. However, these seals undergo deformation because of the vibrations of the rotor, even during normal turbine operating conditions, which may cause an increase in oil leakage. In this study, the oil leakage performance of three labyrinth seals with different types of seal teeth, narrow stainless teeth (Type 1), wide aluminum teeth fixed on the body (Type 2), and fixed wide aluminum movable teeth (Type 3), were evaluated using finite element (FE) and computational fluid dynamics (CFD) analyses. Three-dimensional FE models of the rotor and oil deflectors were developed, and the plastic deformation of the teeth of the labyrinth seals was predicted when the rotor impacted the sealing teeth during turbine operation. The oil leakage was predicted using CFD analysis. The results indicated that the Type 3 seal, including movable teeth, is beneficial in preventing leakage and tooth deformation compared with the other types. The Type 2 seal is advantageous because it results in a smaller increase in gap size and greater vena contracta effects than the Type 1 seal. The results of this study could be helpful when designing and selecting the teeth of a labyrinth seal.

Multi-field coupled dynamics for a movable tooth drive system integrated with shape memory alloys

The harmonic movable tooth drive system integrated with shape memory alloys has a small size and a large output torque. Its dynamics performance is the key factor for evaluating the drive system. Here, for the drive system, based on its structure and working principle, the coupled dynamics equations are deduced. Using the equations, changes of the natural frequencies of the drive system during the operation are investigated. Effects of the system parameters and SMA wires phase change process on the natural frequencies are analyzed. The nonlinear resonant frequencies of the drive system and its amplitude-frequency relationship are studied. Results show that natural frequencies of the drive system change periodically which is caused by SMA phase transformation during operation. The eccentricity, movable tooth radius, the wave generator radius and SMA wire length have also important effects on the natural frequencies of the drive system. The nonlinear resonant frequencies are smaller than linear resonant frequencies. In the design of the drive system, the coupled nonlinear effects of the temperature, phase change, stress and strain of the SMA wires, and the system parameters of the movable tooth drive system should be considered. In this paper, the coupled nonlinear dynamics model of the harmonic movable tooth drive system integrated with shape memory alloys is proposed in which the coupled effects of the temperature, phase change, stress and strain of the SMA, and the system parameters of the movable tooth drive system are considered.

Dens connatalis – A rare case report of natal teeth with literature review

It is unusual for babies to have teeth at birth or within a month of delivery. For a good differential diagnosis of whether there are extra teeth, Bhon nodules, or dental lamina cysts, a proper clinical and radiographic examination is required. The clinic branch received a rare case of natal teeth for this report's subject. An 18-day-old male new-born was checked because he had two mandibular incisor natal teeth. Because of the risk of aspiration and the patient's refusal to eat, the movable teeth had to be removed. Each patient is assessed individually to determine the best course of treatment, which may involve observation, tooth whitening, or extraction.

A double-stage movable tooth reducer with cam wave generator

A double-stage movable tooth reducer with cam wave generator

Local Interventions for the Management of Pain Associated with Orthodontic Treatment in Saudi Arabia

Objectives: The systematic review objective was designed to assess the effects of local interventions used for the prevention and treatment of pain associated with orthodontic treatments. Methods: A digital literature search was carried out between 2000 and 2022 in the following databases, Scopus, Google Scholar, PubMed, and the Cochrane Library of Systematic Reviews. Results: Orthodontic patients' quality of life was significantly impacted negatively by the discomfort associated with fixed orthodontic equipment. There were poor dental hygiene, slurred speech, difficulty chewing, movable teeth, decreased taste, halitosis, and gingival bleeding which were frequently the main indicators of pain. Conclusion: Patients might, to some extent, prevent pain and suffering with the support of effective orthodontist- patient dialogue and targeted dietary guidance. However, analgesics continue to be a trusted and widely used method for subsiding painful sensations.

Coupled vibration for a two-stage movable tooth drive system

Coupled vibration for a two-stage movable tooth drive system

Static Modelling and Analysis of a Novel Movable Tooth Drive with Logarithmic Spiral Tooth Profiles

This paper presents a static model for a novel movable tooth drive with logarithmic spiral tooth profiles, to research contact force and load distribution during the meshing period. According to the geometric properties of the conjugate tooth profiles, their compatibility law considering the multi-tooth elastic meshing effect are investigated to reveal load distribution characteristic of the teeth. The static model of the mechanism is thus developed to systematically analyze variation in contact force during the rise travel. The results indicate that the contact force between the tooth and ring gear is proportional to the curvature radius of the contact point, and it increases exponentially and monotonically corresponding to the curvature radius of logarithmic spiral tooth profile; in the multi-tooth meshing condition, the load distribution of the teeth coincides with the ratio of the curvature radius of each contact point, and periodical pulsations of total contact force occur at the alternation of the teeth. Finally, the proposed model is validated by the FEM simulation of a prototype, and the influence of dimensional parameters is further discussed for the self-locking and force transmission characteristics of the tooth. The outcomes provide critical technical support for the static modelling and design of such transmission mechanism.

Analysis of bifurcation and chaotic behavior for the flexspline of an electromagnetic harmonic drive system with movable teeth transmission

To develop the miniaturization of the electromagnetic harmonic movable tooth drive system, a novel configuration with an inner stator is proposed to create a great compressed structure. To avoid undesirable design parameters that lead to bifurcation and chaotic behavior of the flexspline, the nonlinear dynamic equations of the flexspline are established, and the Duffing equation and analysis results for the chaotic vibration of the flexspline are obtained by using the Donnell-Karman theory of thin-walled cylindrical shells with employing large deflection, the Bubnov-Galerkin principle, and the Melnikov function, separately. According to initial system parameters, based on the bifurcation diagrams, phase diagrams, displacement time course diagrams, and Poincare maps of the flexspline vibration, the dynamic behaviors are investigated, and the stability and chaos intervals are obtained. This study aims to reveal the influence of parameters on the chaotic phenomenon of the flexspline and to provide a theoretical reference for the design of the electromagnetic movable teeth drive.

Analysis of Load Inhomogeneity of Two-Tooth Difference Swing-Rod Movable Teeth Transmission System under External Excitation

In order to improve the load state of the two-tooth difference swing-rod movable teeth transmission system, in this paper, a dynamic equivalent calculation model of the transmission system is established based on lumped parameter theory, and then a calculation method of system dynamic load is derived. The influence of external excitation on load inhomogeneity of the transmission system is analyzed from a dynamic point of view. The theoretical results are verified by Adams dynamic load simulation analysis and strain test based on a test bench. The results show that when errors of the transmission system are fixed, the system load inhomogeneity is improved effectively with the increase of load torque, while the system load inhomogeneity becomes worse as input speed increases. This study provides a theoretical reference for improving the load inhomogeneity of the two-tooth difference swing-rod movable teeth transmission system.

A design method for a novel movable tooth drive with logarithmic spiral conjugated tooth profiles

This paper presents a method for designing a novel type of movable tooth drive characterized by logarithmic spiral conjugated tooth profiles, which are in almost full surface contact owing to such innovative tooth geometry, in comparison with the conventional involute or cycloidal tooth profiles creating a linear contact. Firstly, the existence conditions of the conjugated curve of the logarithmic spiral are researched by establishing the meshing equation, and its geometric and kinematic properties are identified to design the conjugated tooth profiles of the movable tooth and ring gear. Then, wave generator profile, according to the requirement that it should be completely convex and smooth, is designed and modified to ensure the consistency with load capacity of the conjugated tooth profiles. On this basis, dimensional synthesis of the mechanism is performed following the influence analysis of main factors on the force/motion transmission characteristic of the whole machine. Finally, the virtual prototype is developed and the proposed design method is validated by relevant force performance simulation. The outcomes lay a significant foundation for the design of such logarithmic spiral tooth profile transmission.

Study on the performance of a novel hydrodynamic cavitation device for treatment of wastewater

AbstractA novel rotational hydrodynamic cavitation device (called WLAC, composed of rotor and stator) was designed for treatment of wastewater, as well as two other structures with different lead angle based on WLAC, namely, LLAC and HLAC. The velocity characteristics, cavitation number, cavitation bubbles distribution, and production capacity of the hydrodynamic cavitation device were analyzed. Experimental results showed that the concentration of ·OH increased with treatment capacity as the water was decomposed into ·OH and ·H due to cavitation, which indicated the feasibility of the designed cavitation. The high velocity was mainly distributed around movable teeth and decreased to both sides in WLAC but was distributed between the groove of fixed teeth in LLAC and HLAC, as well as the cavitation region. Meanwhile, the cavitation intensities of HLAC and LLAC were significantly higher than WLAC; especially, the cavitation bubbles generated by HLAC were 54% higher than those generated by WLAC. In addition, the production capacity of hydrodynamic cavitation device decreased with the increase of Re. Due to the stronger capability of cavitation cloud generation and suppression of short circuit flow, the HLAC had higher production capacity of cavitation. The results presented here may provide a workable reference regarding the cavitation generation mode on higher cavitation performance and production capacity for wastewater treatment.

Research on performance test analysis method of mechanical structure based on measured error / virtual simulation

Mechanical errors seriously affect the transmission performance of mechanical structure, especially for high-precision mechanical structure. With the development of virtual simulation technology, the performance test of mechanical structure in virtual environment is gradually applied. Under the background, this paper takes the movable tooth reducer as the research object and puts forward a virtual performance test method by combing test errors with virtual simulation technology. The tooth profile errors of key components of the reducer are obtained by optical scanning, and the simulation test is carried out. Meanwhile, the accuracy of the simulation test is verified by the implementation of vibration test. The results show that both the simulated vibration acceleration and the experimental test vibration acceleration show a double-peak variation trend, and the frequency difference between the two peaks is less than 5%. Therefore, the simulation test method proposed in this paper can effectively evaluate the performance of mechanical structures.

Parametric design of inner teeth of center wheel in electromagnetic harmonic movable teeth transmission

In order to improve the rationality and design efficiency of the structural parameters of the electromagnetic harmonic movable teeth drive system, the rationality of the set parameters is judged based on theoretical calculation, and visual programming is carried out by using VB. The designer only needs to input the set parameters into the specified dialog box to get the corresponding output results, which makes the design of the inner teeth of the center wheel more convenient and fast.

Особливості заміщення дефектів зубних рядів у осіб із захворюваннями тканин пародонта різного ступеня тяжкості

Resume. The high prevalence of periodontal disease causes the urgency of finding ways to improve methods of diagnosis, treatment and prevention of complications of this disease. The complex clinical picture requires a differentiated approach to the choice of orthopedic rehabilitation of such patients taking into account the patient's age, degree of pathological changes and activity of the pathological process with mandatory immobilization of movable teeth by different types of splints and splint dentures. Depending on the degree of pathological changes in periodontal tissues, the size and topography of dentition defects and the severity of destructive-resorptive processes in the alveolar bone, the replacement of dentition defects should be planned using dental implants and splinttype dentures. The aim of the study. Improving the effectiveness of orthopedic treatment of periodontal diseases, burdened by defects of the dentition through the differentiated use of dental implants and splinting structures. Materials and methods. A comprehensive clinical and laboratory examination of 237 patients with clinically diagnosed periodontitis I–III degree, burdened by partial loss of teeth. From the specified contingent of persons we carried out orthopedic treatment of 98 patients aged from 30 to 69 years with periodontal diseases of various severity, aggravated by defects of dentitions of various size and localization. Cone-beam computed tomography was used for objective quantitative and qualitative assessment of periodontal tissue and bone tissue of the edentulous jaw in individuals with various clinical forms of periodontal disease, to determine the relative densitometric density of bone tissue, when planning dental implantation and for control its results. The localization of supracontacts was determined by occlusion. Diagnosis and elimination of traumatic occlusion were performed according to Jenkelson and Schuller [3]. Evaluation of the stability of dental implants was performed by frequency – resonance analysis of the stability of dental implants using the Osstell ISQ device. Results. According to the results of examination of 237 people and the division of patients into three age groups, the clinical features of the pathological process in the age aspect were established. The results of computed tomography of the dental apparatus of the subjects showed that periodontal disease in the age aspect in the dynamics is accompanied by the severity of destructive-resorptive processes in the alveolar bone, which are manifested in a decrease in the relative densitometric density of bone marrow and bone loss. Orthopedic rehabilitation of this contingent of persons was performed with the use of biologically indifferent structural materials and splinting orthopedic structures, including splinting of abutment teeth, removable prosthetics and dental implantation, as well as accompanying physiotherapy of prostheses. In the case of periodontitis of I–II degree with sufficient volume and density of bone tissue in the area of the dentition defect, high clinical efficacy was shown by the use of dental implantation in the case of gradual loading of the dental implant using a superstructure of own development. In the presence of medium and large defects of the dentition on the background of periodontitis II–III severity in the presence of significant pathological mobility of abutment teeth and insufficient volume and density of bone tissue in the area of the defect sufficient clinical effectiveness showed the use of removable dentures own design. Conclusions. Periodontal diseases in the age aspect in the dynamics are accompanied by pronounced destructive-resorptive processes in the alveolar bone, which are manifested by a decrease in the relative densitometric density of bone tissue and progressive loss of height of the alveolar process. Timely application of dental implantation due to the dosed gradual occlusal load on the alveolar bone helps to preserve the structure of the alveolar bone and the height of the alveolar process. In the presence of medium and large defects of the dentition on the background of periodontitis II–III severity in the presence of significant pathological mobility of abutment teeth and insufficient volume and density of bone tissue in the area of the dentition defect, the use of removable dentures of splinttype design is shown. To prevent complications of prosthetics and prolong the use of orthopedic structures, it is advisable to use photodynamic maintenance therapy. Key words: periodontal tissue disease, dentition defect, dental implantation, splint-type denture.

Evaluation of Oral Health Status and Oral Care of Patients with Rheumatoid Arthritis.

Objective Rheumatoid arthritis (RA) and periodontal disease (PD) are common chronic, immunoinflammatory, destructive, and progressive diseases; however, the correlations between those two are not yet widely discussed. The purpose of this study was to evaluate the relationship between the selected demographic and clinical parameters of RA patients and oral health status parameters, on the basis of self-assessment. Materials and Methods Three hundred patients under treatment were included in the study. Questionnaires were completed by 164 out of 300 patients. Results A total of 100 females and 64 males took part in the study, with a mean age of 65 ± 11.1 years. In younger patients, the disease activity score (DAS28) was higher, and it was associated with pain or discomfort in the oral cavity and with difficulties in toothbrushing. Discomfort or pain in the oral cavity was to a significant extent associated with the poor gingival state, gingival bleeding, and difficulties in biting or chewing. Conclusions In RA patients, difficulties in biting or chewing, discomfort or pain in oral cavity, feeling of the presence of movable teeth, and gingival bleeding are indications of periodontal infection. Maintaining awareness of oral health and RA is a key issue in the simultaneous management of proper oral care and RA due to the mutual influence of those two factors.

Heat Conduction and Temperature Rise for a Planar Movable Tooth Drive

Abstract Planar movable tooth drives have a compact structure. However, as the size decreases, the heat dissipation capacity decreases; therefore, temperature control is required. A heat conduction model of the drive system, including the central wheel and movable tooth, is established, and the meshing point of the movable tooth and center wheel is considered the heat source. The heat flux density at the meshing point is determined, and the analytical equations describing the temperature increases of the center wheel and the movable tooth are derived. The effects of the input power and system parameters on the temperature increase of the system are analyzed. The results show that the temperature difference of the movable tooth is about 1.5 times the temperature of the center wheel, and the temperature increase near the heat source decreases by more than 15 °C as the movable tooth radius increases from 2 mm to 2.5 mm. The movable tooth radius and center distance have significant effects on the temperature increase and can be used as control parameters to prevent a temperature increase of the drive.

Free vibration for a two-stage sinusoidal movable tooth drive system

Two-step sine movable tooth drive has the smallest radial and axial sizes which is especially suitable for oil drilling machine and robot arm. Undesirable dynamic performance will result in noise and unacceptable performance characteristics which should be predicted in the design stage. In this paper, the analytical model of the dynamics for a two-step sine movable tooth drive was proposed. From the model, dynamics equations of the drive system were developed. Using the equations, natural frequencies and vibration modes of the drive system were investigated. Effects of the drive parameters on the natural frequencies were analyzed. The results show that the vibrations of the two-step sine movable tooth drive include two mode types: rotational mode and movable tooth mode. Mesh stiffness between movable teeth and related elements has important effect on the dynamics performance of the drive system. For a special mesh stiffness value, mode transition could occur. Mass of the movable tooth and guide has obvious effects on the vibrations of the different elements, respectively.