Worm Gear Research Articles

Undercutting analysis of recess action worm gear drives with double-depth teeth

Undercutting analysis of recess action worm gear drives with double-depth teeth

Meshing performance investigations on face worm gear drive with the variable worm cone angle

Meshing performance investigations on face worm gear drive with the variable worm cone angle

Grinding the side surfaces of the spiroid cylindrical gear worm turns with a tapered wheel

Information about the worms’ production technology of spiroid cylindrical gears is given. A method of the profile analytical calculation of a disk abrasive tool is proposed, providing the possibility to profile grinding wheels for various types of ruled helical surfaces: Archimedean, convolute, involute, etc. The use of the calculation methodology makes it possible to achieve high accuracy in processing the active (working) side surfaces of a hardened grinding worm; it sharply reduces the wear intensity of the spiroid wheel associated with it, the ring gear of which is made of bronze.

Pivotal errors identification of the face gear worm grinding machine tool with a piecewise sensitivity analysis

As one of the main error sources, geometric errors greatly affect the machining accuracy of the face gear worm grinding machine tool. To reveal the mapping rules between the geometric errors and the tooth surface errors (TSEs) of face gear, the tool comprehensive error model (TCEM) and the tooth surface error model (TSEM) were successively established. The TCEM expressed the relationship between 41 geometric errors of the machine tool and 6 tool comprehensive errors (TCEs) of the tool while the TSEM expressed the relationship between 6 TCEs and 3 TSEs. Then, using the improved Sobol method, a piecewise sensitivity analysis was carried out by calculating the sensitivity indexes of the input of the TCEM and TSEM individually. Finally, the joint sensitivity indexes were calculated and the pivotal geometric errors were identified. By modifying the pivotal geometric errors in each TSE direction separately, all the main error reduction rates (ERR) are greater than 70%. Besides, by modifying all the pivotal geometric errors, the maximum values of 3 TSEs are reduced by 73.7%, 74.7% and 86.96%, respectively, and the minimum values are reduced by 57.1%, 71.79% and 76.19%, respectively, confirming the validity of the identified results.

EXPERIMENTAL TESTS TO ASSESS THE DYNAMIC CHARACTERISTICS OF WORM GEARBOXES

The article deals with the issue of experimental assessment of the dynamics of worm gears. The design of the methodology and the material and technical assurance of experimental tests to determine the impact of the use of various structural modifications on the dynamics of the worm gear are described. In the pilot part of the experiment, a gearbox was tested with an original design solution of bearing the worm wheel shaft in special damping inserts. The goal is to find ways to reduce the dynamic load of the most stressed components of the worm gear and increase their service life.

A Bow‐Drill Structured Triboelectric Nanogenerator for Marine Ranching Monitoring

AbstractTriboelectric nanogenerator (TENG) is one promising method of wave energy harvesting for marine ranching monitoring. Different from previous studies with complex structures (gears, racks, worm gears, or screw‐nut), a bow‐drill structured TENG (BS‐TENG) with a simple, cheap but effective rope‐roller structure is proposed and investigated to magnify the wave motion frequency. Inspired by the bow‐drill for carpentry, the proposed structure only simply needs a rope and roller to transfer the random wave motion into regular rotary motion with higher frequency. Results show that the structure parameters (flexible paddle number NP flexible paddle length L, electrode number NE and shaft side length D) have a great influence on the working performance of the BS‐TENG. The maximum frequency magnification ration (Rm) is 74 under the condition of 130 mm wave height (Hw); the maximum output power (P) is 450 µW. Demonstration experiments verify that the BS‐TENG is able to charge the thermo‐hygrometer and light emitting diode lights for marine ranching. Combined with the Internet of Things and 5G technologies, the BS‐TENG could be applied in the offshore sensor system for the monitoring of marine ranching information.

COMPARATIVE SERVICE LIFE ANALYSIS FOR WORM GEARS ACCORDING TO DIFFERENT FAILURE CRITERIA

In this paper, a comparative analysis of the service life of worm gear wheels for various failure criteria is carried out. Based on this analysis, a method is proposed for selecting the worm gear wheel material, the values of the modulus, on which the bending strength of the teeth depends. Research has shown that increasing the bending strength of teeth is of great practical importance, both for one-sided and two-sided loads. This also makes it possible to significantly increase the lifetime of one-side loaded gear wheels by replacing their working flanks with non-working ones. it was proposed to replace the working surfaces of the teeth of worm wheels after a certain service life.

Mathematical modeling and forming method of rake face of toroidal worm gear hob based on conical production surface

In order to improve the cutting performance of toroidal worm gear hob and the tooth surface accuracy of hobbing worm gear, to control the absolute value of the side rake angle of each cutter tooth to be smaller and more balanced on the left and right sides, a method of developing the rake face of toroidal worm gear hob with spiral groove by using conical production surface is proposed. According to the theory of gear meshing rationality, the mathematical model of the rake face is established. The analysis and calculation example results show that the absolute value of the rake angle on both sides changes with the transmission ratio coefficient. By studying this change law, the optimal milling transmission ratio coefficient k = 0.886 is obtained. Meanwhile, the corresponding absolute value of the rake angle is between ±4.5°, which reduce the absolute value of the rake angles on both sides of the cutter teeth effectively and make the rake angles on the left and right sides be more balanced. The spiral groove was simulated, and the rake angle was measured in the simulation software. The measured results are consistent with the calculated results, which prove the correctness of this method.

Dynamics modeling of gear transmissions with asymmetric load-dependent friction

This paper proposes a new concise mathematical model of gear transmission dynamics with asymmetric load-dependent friction. It is built only upon the rigid-contact mechanics and the Coulomb friction law, but provides a new theoretical perspective on dynamic and static characteristics of gear transmissions. The presented model is of the form of a differential–algebraic inclusion (DAI) characterized by some parameters, including input-side and output-side asymmetry coefficients. The presented model properly captures the static friction and even the non-backdrivability. It is applicable to different classes of transmissions, such as leadscrew transmissions, worm gear transmissions, and spur gear transmissions. The DAI representation is extended into a multi-dimensional representation for articulated rigid-body systems driven through joint transmissions. Moreover, simulation algorithms are derived through the implicit Euler discretization. Some simulation examples illustrate the capability of the presented simulation algorithm to reproduce load-dependent asymmetric frictional behaviors, which cannot be reproduced by conventional load-independent joint friction models.

Effect of Grating Ruling Machine System Errors on Grating Spectral Performance

Grating groove functions scalar theory can describe the light source through the grating interference and diffraction effect of the physical phenomenon of splitting light. It can be used to represent the distribution of the complex amplitude of the illumination light source on the diffraction screen under the action of the diffraction grating and display the information on the diffracted light position and intensity distribution. As a result, the effect of groove error on the intensity of grating ghost lines and stray light is analyzed. This paper presents an energy solution and analysis of the grating periodic groove error utilizing the grating scalar diffraction theory. Based on this, the effect of the core components of the grating ruling machines, such as screw and worm gear, on the stray light and ghost line of the grating is analyzed. Finally, the random groove error is analyzed. The analysis results show that the worm gear error is an important reason for the appearance of ghost lines in the machine ruling grating, and the lead screw error and random grooving error are the main reasons for the stray light produced by the grating. We optimize the worm gear, lead screw, and error compensation system of the grating ruling machine to effectively improve the ruling quality of the grating.

Einfluss des Substratmaterials bei der Transferschmierung von Stahl- Bronze-Kontakten mit PA66-PTFE-cb Trockenschmierstoffen

In this work, the dependence of the friction and wear behaviour in dry-lubricated steel-bronze contact on the dry lubricant used and on the substrate material (steel or bronze) under constant load was investigated. For this purpose, a block two-disc test rig was used, with the dry lubricants PA66-PTFE-cb as blocks, which were produced via chemical bonding (cb) of polyamide 66 (PA 66) and radiation-modified polytetrafluoroethylene (PTFE). The results provide a good basis for the selection of a suitable dry lubricant and the counter body for the transfer of the dry lubricant in dry lubricated worm gears consisting of a steel worm and a bronze wheel.

Geometry, kinematics and synthesis of abnormal hourglass worm gearing with centering bearing contact and lower error sensitivity

The proposed abnormal hourglass worm gearing is a novel type of point-contact transmission that is insensitive to installation errors, has good meshing performance, favorable bearing contact and high manufacturing accuracy. Based on Differential Geometry and Gear Meshing Theory, the systematic meshing theoretical analysis and synthesis is carried out. By complementing concept of datum points and contact endpoints, the theory of tooth contact analysis (TCA) is developed, and the non-linear contact equation used to solve the momentary contact point is simplified into the equivalent form of one-variable by elimination method; A synthesis design is carried out from the desired meshing behavior, which allows more accurate acquirement of favorable parameter scheme; The influence of the contact trajectory direction on the eccentricity of the contact ellipse is further analyzed; The meshing performance with centering bearing contact and lower error sensitivity are demonstrated by tooth contact simulation. The described meshing theory and synthesis can also be applied effectively for other point-contact gearing.

Investigation and Analysis of Existing Design of Worm and Worm Wheel of a Gear Motor used in a Soot Blower

A Soot Blower is one of the crucial equipment used to remove the soot in the Boiler. It is required high reduction ratio gear box with high working torque during the operation. Worm and Worm Wheel are best suited gear set to fulfill the requirement of Soot Blower. Worm and Worm Wheel are the key component of a Soot Blower. The performance of Soot Blower is mainly depending on efficiency and life of Worm and Worm Wheel. Currently-one of Soot Blower manufacturer is using 45:01 gear reduction ratio Worm and Worm wheel gearbox which delivers approx.500 N.m output torque for short period that is 5 min in one-hour time cycle. As this equipment runs for long period of time, maximum output is required. So, the purpose of this study is to examine and analyse the existing industrial design of Worm and Worm Wheel in order to improve the Soot Blower's future performance. The approach for investigating and analysing existing designs of Worm Gear sets used in soot blowers is also supported by FEA data and analytical calculations. This study will serve as the foundation for future research into the performance enhancement of Soot blowers.

Experimental investigation of efficiency of worm gears and modeling of power loss through artificial neural networks

In this study, an experimental system that can operate at different speeds and loading rates was developed for the efficiency calculations of worm gears (WGs), and measurements were made accordingly. A comprehensive efficiency analysis has been made for WGs based on power loss calculations under different operating conditions. The efficiencies obtained from the healthy gearbox were also compared with three different gearboxes with different failures (pitting, wear and breakage). The negative effect of the faults on the efficiency that may occur in the gearbox has been investigated comparatively. A widely used type of machine learning algorithms, called artificial neural network (ANN), is applied for data-driven modeling of the power loss in WG under different operating conditions. The input and output power of the gearbox are utilized to design an ANN-based model for the power loss.

Mist-edge-fog-cloud computing system for geometric and thermal error prediction and compensation of worm gear machine tools based on ONT-GCN spatial–temporal model

The geometric precision of worm gears (WGs) determines the service performance and life of precision machine tools, indexing turntables and other equipment. The machining accuracy of worm gear machine tools (WGMTs) is the core to guarantee the geometric precision of WGs, and is greatly affected by the thermal and geometric errors. To improve the machining accuracy of WGMTs, the thermal and geometric errors should be controlled and compensated. But the control system has a poor real-time performance, and the synchronous control of the geometric and thermal errors cannot be currently achieved, and the thermal error model has a low prediction accuracy and low robustness. To make up for the above gap, a mist-edge-fog-cloud computing system is designed for the error prediction and compensation to relieve the bandwidth pressure of the industrial Internet. Moreover, a sensor network composed of multiple sensors is constructed to obtain the thermal information, and then the ordered neuron temporal-graph convolutional network (ONT-GCN) is proposed based on the ordered neuron-long short term memory network (ON-LSTMN) and graph convolutional network (GCN) for the first time to conduct the spatial and temporal modeling of the thermal error data. The interaction among multiple sensors is explicitly considered, and the dependence of the temporal information of the thermal error data on and spatial information of sensors is taken into account. Besides, to realize the error control, the mapping relationship between the tooth surface error and geometric-thermal errors is established. The error mapping model converts 51 geometric errors and 4 thermal errors into the spatial errors of the hob. Moreover, the sensitivity of errors is analyzed, and then the key error items that affect the geometric precision of the tooth surface are identified and compensated. The results show that the ONT-GCN is superior to traditional time-series modeling methods and that the mist-edge-fog-cloud computing system can effectively shorten the executing time compared with other system frameworks, and can improve the machining accuracy of WGMTs.

New Approach to Study the Dynamic Performance of Worm Gear Drive Model

New Approach to Study the Dynamic Performance of Worm Gear Drive Model

Identification of crucial geometric errors of face gear grinding machine based on geometric error-tooth surface normal error model considering worm dressing

The existence of geometric error (GE) of the grinding machine leads to a great decrease in the accuracy of worm dressing and face gear grinding. Currently, scarce researches consider the influence of GE of the grinding machine on the tooth surface normal error (TSNE) of face gears in the whole process from worm dressing to face gear grinding. For straightly disclosing the mapping laws between the GE and TSNE, the whole process from worm dressing to face gear grinding, and the interaction between the worm and face gear tooth surface are simultaneously considered to establish the GE-TSNE model (GE-TSNEM). Then, the crucial GEs are identified through global sensitivity analysis combined with actual GE measurement results. Finally, the validity of the identification results is verified. The results show that the crucial GEs in the whole dressing-grinding process can be effectively identified through one calculation by the GE-TSNEM. More than 25% of the crucial GEs originate from the worm dressing process, and the consideration of the worm dressing process is indispensable when establishing the GE-TSNEM. The correctness of the identification results and the validity of the method are verified as the total error reduction rates are higher than 75%.

Study on the meshing stiffness of plastic helical gear meshing with metal worm via point-contact

Time-varying meshing stiffness is the main internal excitation source for gear dynamic responses. A calculation method for meshing stiffness of point-contact transmission pairs is proposed to analysis the dynamic responses of the plastic helical gear metal worm drive. Based on the curvilinear motion trajectories and the contact ellipse changes of helical gear worm drive, a method of equivalent area rectangle is introduced to convert the contact ellipse into contact line, and the relationship between the contact line and the worm angle is established. The meshing stiffness of plastic helical gear metal worm drive is calculated and compared with the finite element method (FEM) to verify its accuracy. The results show that the meshing stiffness of plastic helical gear metal worm drive is affected by the meshing impact, and the time-varying meshing stiffness value of double-tooth meshing will be close to or even lower than that of single-tooth meshing. In the plastic helical gear metal worm drive, there is no stable stiffness value whether it is single-tooth meshing or double-tooth meshing. The single-tooth meshing stiffness has an upward trend under the influence of the pressure angle. The calculation results of theoretical model are basically consistent with the FEM results, but the theoretical model cannot fully reflect the stiffness change during meshing impact.

Meshing theory of offsetting Archimedes cylindrical worm drive

The main purpose of this article is to establish the meshing theory for the offsetting Archimedes cylindrical worm drive, which consists of a cylindrical worm with asymmetric tooth profile and a plane worm gear. The equations of the tooth surfaces, the meshing function, the curvature interference limit function, and the curvature parameters are all obtained for the worm drive. By means of the developed reference-point-based meshing theory, the reference point located strictly on the tooth surfaces of a worm drive is determined via solving the system of nonlinear equations, in which no iteration is needed to perform this process. Based on the location of the reference point, the tooth surface boundaries are ascertained for the plane worm gear. The numerical case is carried out and the conjugate zone, the instantaneous contact lines, and the local meshing property parameters are acquired for the worm drive. The whole thread length of the cylindrical worm can almost be used and the conjugate zone can cover the whole tooth surface of the mating plane worm gear. In the meshing zone, not only the contact stress level between the tooth surfaces is relatively low, but also the lubrication condition is favorable. The comparative study on the meshing properties between the offsetting Archimedes cylindrical worm drive and the Archimedes conical worm drive is carried out.

Study of Contact Strength, Tooth Wear and Metal-Polymer Life of Worm Gears

Study of Contact Strength, Tooth Wear and Metal-Polymer Life of Worm Gears