Gear Grinding Research Articles

Prediction model for surface generation mechanism and roughness in face gear grinding

Prediction model for surface generation mechanism and roughness in face gear grinding

A topological flank modification method based on contact trace evaluated genetic algorithm in continuous generating grinding

A method for topological modification of gear flanks in continuous generating grinding based on contact trace evaluated genetic algorithm (CTEGA) has been proposed to solve the problem of flank twist caused by lead modifications of gear flanks. Firstly, according to the theory of conjugate surface, a mathematical model calculating the generating surfaces of worm wheel as well as representing the wheel as two-parametric form spiral surface has been established. Secondly, by representing the radial, axial, and tangential feed of worm wheel in forms of polynomials of the axial feed of worm wheel, a mathematical model of generating gear grinding process has been established where the axis linkage relationship in CNC machine is intentionally changed for topological modification of target tooth surface. Finally, the validity of the proposed topological modification method was numerically demonstrated using a helical gear made by the CNC continuous generating grinding machine. The method proposed in this paper can realize the topological modification of gear flanks by only adjusting motions of numerically controlled axes in the grinding process without adopting a specific dressing of the grinding wheel.

The New Gear Finishing Method Research for Highly Loaded Gears

Achieving roughness parameters on tooth flanks for highly loaded gears and creating their non-directional surface texture are key to obtaining the required gearbox lifetime, durability, and performance. Many finishing techniques are well-known and described in technical literature, including gear teeth final grinding, shaving, honing, and superfinishing to create the proper surface condition. Unfortunately, there is still a lack of a simple finishing method which can be applied to highly loaded gears in the manufacturing process in order to optimize cost, time, and waste. This work presents the effect of a non-chemical, abrasive, highly effective process to remove quite a large amount of material from gear teeth flanks. The researched technology is called Stream Finishing (SF). The surface condition was inspected to observe its properties before and after the proper SF process parameters definition. It is useful for transmissions groups to define the proper manufacturing process application for obtaining the required gearbox lifetime within optimized parts cost. For each application the process parameters definition shall be determined individually and tested.

Technological possibilities of increasing the strength of cylindrical gears

In order to increase the bending and contact strengths of cylindrical gears, after chemical heat treatment, their teeth, as a rule, are subjected to shot peening and subsequent finishing machining. Studies have shown that mechanical heat grinding of gears with worm grinding wheels made of cubic boron nitride provides higher compressive stresses in the surface layer of the teeth and higher bending and contact strength compared to grinding with abrasive wheels. Keywords: gear grinding, shot peening, tooth strength, internal stress, chemical heat treatment. alexandr_kalashnikov45@rambler.ru, morgunov@mami.ru, chelendger1@mail.ru, ggglilo@mail.ru

Exploratory investigation of chip formation and surface integrity in ultra-high-speed gear hobbing

Gear hobbing is widely employed to manufacture automotive gears, where the productivity depends on the cutting speed. Currently, gear hobbing is performed at ∼300 m/min using high-speed steel hob cutters. In this study, ultra-high-speed gear hobbing was attempted using a large-diameter cemented carbide hob cutter on a gear grinder. This enabled a cutting speed up to 2450 m/min. Many interesting phenomena were acquired in this speed range. Chips were severely oxidized, whereas the gear surface was not affected. Compressive residual stress was generated at the gear surfaces with low surface roughness and high hardness, while the wear of hob cutter was insignificant.

Investigations on five-axis milling and subsequent five-axis grinding of gears

High-productivity processes such as gear hobbing and gear grinding are normally used in the manufacturing of gears. In some applications, however, the use of these processes is not possible due to accessibility. One example is the production of planetary gears with double helical teeth for the gear box in modern aircraft engines. The gear boxes are used to increase the efficiency of the engines but should be as light and compact as possible. Thus, the tool runout area for gear hobbing or gear grinding tools is too small. One way of manufacturing these gears is five-axis machining. While five-axis milling of gears has been the subject of several publications, five-axis grinding of gears has hardly been a topic. This paper presents the results of investigations on five-axis milling and subsequent five-axis grinding of gears in comparison to conventionally manufactured gears. For this purpose, after hardening, gears were first five-axis milled and then five-axis ground using different process parameters and then investigated on back-to-back test rigs regarding load carrying capacity. In addition, the dimensional accuracy was measured and the surfaces were examined metallographically. The dimensional accuracy became worse after five-axis grinding. However, in terms of gear life, the five-axis milled and then five-axis ground variant showed an increase of 8.2 % compared to the conventionally manufactured gear which indicates a high potential for further research in regard to the presented five-axis machining process chain of gears.

Efficient and accurate worm grinding of spur face gears according to an advanced geometrical analysis and a closed-loop manufacturing process

Efficient and accurate worm grinding of spur face gears according to an advanced geometrical analysis and a closed-loop manufacturing process

Modeling of Probe Comprehensive Pre-travel Error For On-machine Inspection System of Gear Grinder

Modeling of Probe Comprehensive Pre-travel Error For On-machine Inspection System of Gear Grinder

Force Modeling in Generating Gear Grinding Considering the Grinding Worm Topography

During generating gear grinding, a large portion of the energy generated is converted into heat that can flow into the gear. To better control the heat flowing to the gear, an energy distribution model was developed, which considers chip formation mechanisms of each grain of the grinding worm. The energy distribution calculation requires knowledge of micro-interaction characteristics of grains engaging with the gear. In this paper, a simulation model of generating gear grinding is developed, considering grains micro-interaction characteristics during the process. Ultimately, the calculation of energy distribution is performed, contributing to better knowledge of heat flow into the gear.

Construction and Simulation of Failure Distribution Model for Cycloidal Gears Grinding Machine

To increase reliability, reduce machine tool failure, and shorten maintenance time, serval failure distribution models are discussed based on the cycloidal gears form grinding. A fault data expansion algorithm model based on the radial basis function (RBF) neural network is proposed to accurately evaluate the reliability of cycloidal gears form grinding machines. The model uses a self-organizing clustering learning algorithm to determine the RBF centers and expansion constants of the neural network. It trains the neural network using the learning algorithm’s output and imports the randomly generated cumulative failure distribution function to obtain simulation data. A numerical example of researching failure distribution is presented which shows that the estimated value of mean time between failures (MTBF) is 909.20h, and the estimated value of reliability is 0.4874. Finally, the fault tree analysis-analytic hierarchy process (FTA-AHP) is used to analyze the fault tree of the cycloidal gear grinding machine. The reliability evaluation indexes are obtained by analyzing the corresponding reliability characteristic function, which proves the failure distribution model is valid. It has important guiding significance in evaluating the reliability and performance of large computer numerical control (CNC) form gear grinding machines.

An Analytical Method to Control and Predict Grinding Textures on Modified Gear Tooth Flanks in Cnc Generating Gear Grinding

An Analytical Method to Control and Predict Grinding Textures on Modified Gear Tooth Flanks in Cnc Generating Gear Grinding

IMPROVING GRINDING OF GEAR WHEELS APPLIED IN GEARBOXES OF POWER ENGINEERING

Development of modem power engineering follows the line of continuous increase in speed, coefficient of corrosive action and capacity of units. Gears and reducers are responsible parts of modem machinery and occupy an important place in the domestic power engineering construction. Durability and wear resistance of gears, apart from the design factors, also depends on the technological methods of treatment. The final stage of production of such wheels is the operation of gear grinding. In the process of gear grinding in a thin surface ball there are complex thermomechanical processes. As a result of short-time heating to high temperatures, structural transformations, burns, and in some cases even micro- and macro-thicknesses occur in such a surface bail. In addition, there are cases of making tooth wheels with adjacent defects grinding (for example, the appearance of the surface of the ball teeth of large tensioning forces), which reduces the life of the work, and in some cases causes a breakdown of the teeth in operating conditions. Development of effective measures to ensure the quality of the surface of the ball on the operation of grinding baggage in part depends on the possibility of predicting (or calculation) of temperatures and residual loads on the depth of the cemented teeth ball. The method of calculation of internal surplus Toads occurring during grinding of wheels with cemented steels is suggested. On the basis of the performed calculations and experiments the ways to improve the quality of production of working surfaces of gears, which are used in the wits of thermal and nuclear power plants are suggested and grounded.

PROCESSING OF HARDENED CYLINDRICAL GEAR WHEELS OF THE CUTTING GEARBOX OF THE COMBINE UKD 200-500

The article discusses the latest developments of unique technological methods of gear milling of cylindrical gears for preliminary blade gear processing of hardened cylindrical gears of the cutting reducer of the UKD200-500 coal mining harvester for the final gear grinding of gear teeth with modulus m = 16 mm, with hardness HRC 56 ... 62. The peculiarity of the design of special hob cutters is that a circle passing through the lower boundary points of the involute is used as the palloid of the machine gearing of the tool and part. Pre-cutting the teeth of hardened wheels with carbide milling cutters allows you to remove the main allowance for the final gear grinding.

Optimization of the precision gear grinding operation based on integrated information system

In accordance with the principles of hierarchical management, a comprehensive two-level management system is presented for the development and manufacturing of products for the stages of pre-production (the upper level of the management hierarchy) and for the actual production stage (the lower level of the management hierarchy). At the stage of pre-production, the gear grinding oper-ation design on the “MAAG”type machines was carried out. For this purpose, a technique for optimizing the gear grinding parame-ters for a two dish-wheel rolling scheme has been developed, a mathematical optimization model containing an objective function with restrictions imposed on it has been created. The objective function is the gear grinding machine time, which depends on theoperation parameters (gear grinding stock allowance, cutting modes, grinding wheel specification, part material) and the design fea-tures of the gears beingground (module, diameter, number of teeth, radius of curvature of the involutes). The article showsthat at the stage of pre-production,the gear grinding optimizationis a method of operation design. At the stage of actual production, a closed-loop automatic control system with feedback on the deviation of the adjustable value (gear grinding power) automatically supports the numerical power values that were found at the operation design stage, taking into account ensuring defect-free high-performance gear grinding (minimum number of working strokes and maximum longitudinal feeds). At this stage, i.e. when a robust longitudinal feed automatic control system is operating, the optimization carried out at the previous stage (pre-production) sets the functioning algorithm for the adaptive systemwithcorresponding control algorithm. Thus, at the production stage (when the gear grinding ma-chine is running), the operation optimization is a control method. Therefore, it is shown that with two-level control, the gear grinding operation optimization performs a dual function. On the one hand, it is a design method (at the pre-production stage), and on the other –a management method (at the actual productionstage). With this approach, i.e. with the integration of production and its preparation based on a single two-level management, the efficiency of a single integrated design and production automation system is significantly higher due to general (unified)optimization, rather than partialone.

Error analysis and compensation of cycloid gear form grinding based on multi-body system error topology theory

Error analysis and compensation of cycloid gear form grinding based on multi-body system error topology theory

An innovative geometric error compensation of the multi-axis CNC machine tools with non-rotary cutters to the accurate worm grinding of spur face gears

As one of the main error sources, the geometric errors are compensated in this work for the accurate worm grinding of spur face gears. The previous methods of the geometric error compensation are usually applied to the machining with rotary cutters, of which the error of cutter rotation angle is not compensated since it does not affect the machining result. These methods are inappropriate to the worm grinding of face gears, because the worm is a non-rotary cutter and the machining result is sensitive to the error of cutter rotation angle. In this work, an innovative geometric error compensation method is proposed to the machining with non-rotary cutters based on two main points. First, the cutter rotation angle is considered to both the modeling and compensation of the geometric errors. Second, the instantaneous ideal contact point, which is calculated according to the generation process of the worm grinding of face gears, is chosen as the reference point to the compensation algorithm rather than the cutter tip point used in the previous method. The proposed method is validated by the example with both the theoretical calculation and practical machining.

Consideration of micro-interaction in the modeling of generating gear grinding processes

Consideration of micro-interaction in the modeling of generating gear grinding processes

Detection of Pinion Grinding Defects in a Nested Planetary Gear System using a Narrowband Demodulation Approach

<div class="section abstract"><div class="htmlview paragraph">Nested planetary gear trains, which consist of two integrated co-axial single-stage planetary gearsets, have recently been widely implemented in automobile transmissions and various other applications. In the current study, a non-destructive vibrational and acoustical monitoring technique is developed to detect a common type of gear grinding defect for a complex nested gear train structure. A nested gear train which has an unground pinion with unpolished teeth profile is used to exemplify the developed methodology. An experimental test stand with an open and vertical mounting configuration has been designed to acquire both vibrational and acoustical data. The measured data are investigated using several signal processing techniques to identify unground pinions in the gear system. A general frequency spectrum analysis is performed initially, which is then followed by a peak finding algorithm to identify the peaks in the spectrum. The peak frequency that matches the gear meshing frequency is selected for a further narrowband demodulation analysis. A Hilbert transform based demodulation filtering are then performed on the bandpass filtered signals around each selected frequency to obtain the corresponding instantaneous amplitude and phase signals. These demodulated signals for the gear train with unground gears appear to be different from that with normal gears, which can be used to detect whether grinding defect occurs in a gear train. Furthermore, the frequency spectra of these instantaneous phase and the amplitude signals are shown to exhibit peaks at the rotational frequency of the carrier where the unground pinion is mounted. This information allows the detection the location of the unground gear. The repeatability of results has been confirmed by multiple tests on the experimental setup designed in the current work. It can be concluded that the narrowband demodulation technique can be leveraged to develop an autonomous system for identifying imperfect pinions in a nested planetary gear system.</div></div>

Research on Remanufacturing Technology and Remanufacturing Process of Gear Grinding Machine

Research on Remanufacturing Technology and Remanufacturing Process of Gear Grinding Machine

Digital twin modeling for loaded contact pattern-based grinding of spiral bevel gears

To distinguish with the conventional tooth flank grinding only considering geometric accuracy, an innovative digital twin modeling is proposed for loaded contact pattern based grinding of spiral bevel gears. Where, data-driven grinding simulation, sensitivity analysis strategy, adaptive decision and control are developed. Focusing on loaded contact pattern optimization, numerical loaded tooth contact analysis (NLTCA) considering noncentrosymmetric problem and tooth flank roughness is developed for data-driven relationship establishment. Then, an adaptive data-driven tooth flank grinding decision and control model is established. Where, the universal motion concept (UMC) machine settings is selected as the optimal design variable. It is actually an infinite approximation to the target tooth flank in form of an adaptive control system. Moreover, with point-to-point material removal distribution, the different optimization strategies are proposed for accurate tooth flank grinding. In particular, the overcutting problem on the tooth flank grinding programming is investigated. Finally, Levenberg-Marquardt method is applied to solve the established nonlinear lease square model for the accurate machine tool settings having modification variations. Thus, this accurate data-driven digital twin modeling can achieve loaded contact pattern-based grinding. The provided numerical and test instances can verify the proposed digital twin modeling.