Electronic Gearbox Research Articles

Cutting Force Fluctuation Suppression and Error Homogenization of Noncircular Gear Hobbing Based on the Tool Shifting Method

The current research on noncircular hobbing mainly focuses on the linkage model and motion realization. However, the intermittent cutting characteristics of hobbing would increase uncertainties in the manufacturing process. In this paper, a hobbing machining model with tool-shifting characteristics was proposed to solve the problems of cutting force fluctuation and inconsistency of tooth profile envelope accuracy at different positions of the pitch curve in noncircular gear hobbing. Based on the unit cutting force coefficient method, the undeformed chip volume generated by interrupted cutting was used to characterize the fluctuation trend of the hobbing force. The fluctuation characteristics of the cutting force generated by different hobbing models were compared and analyzed. Using the equivalent gear tooth and hob slotting numbers, an analysis model of the tooth profile envelope error of the noncircular gear was constructed. Subsequently, the tooth profile envelope errors at different positions of the pitch curve were compared and analyzed based on the constructed model. The transmission structure of the electronic gearbox was constructed based on the proposed hobbing model, and the hobbing experiment was conducted based on the self-developed noncircular gear CNC hobbing system. This paper proposes a hobbing method that can effectively suppress the fluctuation of the peak and whole circumference cutting force and reduce the maximum envelope error of the whole circumference gear teeth.

Active disturbance rejection controller for electronic gearbox

In this paper, the active disturbance rejection controller (ADRC) for the electronic gearboxes (EGB) is proposed to solve the problem of gear deviation caused by the change of cutting force. Firstly, we analyzed the principle of the CNC hobbing process and established the machine tool kinematic model and EGB control precision model. Then, to achieve self-compensation for the system disturbance, the ADRC is utilized. In addition, an improved particle swarm optimization algorithm is introduced to address the issue of the ADRC’s parameters being hard to select. Finally, the EGB is designed using a composite structure and combined with the ADRC. We compare master–slave and composite EGB for experimental verification using a CNC hobbing machine as an example. The proposed composite EGB method is obtained through numerical simulation and experiments to effectively verify the EGB control precision of the CNC hobbing machine. Meanwhile, the tracking precision of each motion axis is improved obviously. The proposed composite EGB method solves the issue of self-compensating disturbances in CNC hobbing machine tools from the controller design. It provides a novel design method that can apply to all kinds of CNC machine tools to deal with disturbance problems.

Research on Gear Flank Twist Compensation of Continuous Generating Grinding Gear Based on Flexible Electronic Gearbox

Gear flank twist occurs when threaded wheel grinds crowning lead modified helical gears, which reduces gear machining accuracy. To overcome this problem, a flank twist compensation method based on flexible electronic gearbox is proposed in this paper, the method can reduce the degree of twist and improve gear machining accuracy. Firstly, flank equations of gear and threaded wheel are established, coordinates and normal vectors of gear flank are used to represent twist. Secondly, coordinate transformation matrix between workpiece and tool coordinate system is established based on multi-body system theory and homogeneous coordinate transformation, and relationship between coordinates and normal vectors of gear flank and master-slave axis (B-axis, C-axis, X-axis, Y-axis, Z-axis) movement amount is obtained by inverse kinematics and electronic gearbox, then master-slave axis movement compensation amount between crowning lead modified flank and twisted flank is obtained. Finally, twist is compensated by compensating for master-slave axis movement amount, and flank contact analysis based on KISSsoft is carried out to observe normal force and contact stress of flanks. This paper uses inverse kinematics and electronic gearbox to realize flank twist compensation, which makes up for long period and high cost of traditional flank twist compensation by changing shape of threaded wheel. Simulation results show that this method can effectively compensate for flank twist and improve accuracy and efficiency when threaded wheel grinds crowning lead modified helical gears.

Linkage model and interpolation analysis of helical non-circular gear hobbing

The design flexibility and transmission stability of the non-circular gears can be improved using the helical tooth scheme. Herein, a linkage model was derived for hobbing the helical non-circular gears based on the influence of the axial feed motion of the hob on the motion of the projecting rack on the gear-blank end face. This axial feed motion produces additional motion effects on the rotary axis of the gear-blank and the moving axis of the hob. Further, the accuracy of the linkage model was verified by kinematic simulations. The global convergence characteristics of the transcendental equation used for obtaining the polar angle of the pitch curve were ascertained to derive the interpolation calculation process for the linkage model-based electronic gearbox. The cause of cumulative error during the multi-turn hobbing process of the gear blank was analyzed. The error accumulation was effectively controlled by optimizing the interpolation algorithm. The hobbing experiments and meshing transmission test were conducted using the self-developed non-circular gear hobbing system to verify the effectiveness of the linkage model and interpolation algorithm.

Online estimate and compensation of the gear machining error based on electronic gearbox cross-coupling controller

A novel method for online estimate and compensation of the gear machining error based on the flexible electronic gearbox (EGB) is introduced. EGB is a multi-axis controller, which is used to realize the gear generation process. Gear processing quality is directly dependent on the control precision of EGB. The present work focuses on the estimation, analysis, and compensation of the gear machining error during the gear hobbing process. First, an efficient method for the online evaluation of the helical gear tooth profile deviation, pitch error, and helix deviation is presented, from the perspective of the combination of the multi-axis linkage control structure model and the gear processing technology. Second, the online compensation architecture for the five-axis gear hobbing linkage is proposed, which is composed of an asymmetric cross-coupling controller and a master-slave EGB controller. Simulation results show that the proposed online compensation architecture has better control precision, in comparison to the conventional EGB. Finally, experiments are performed on a six-axis gear hobbing machine, where higher accuracies are obtained for the helical gear, processed by the proposed method.

УСОВЕРШЕНСТВОВАНИЕ СИСТЕМЫ АВТОМАТИЗИРОВАННОГО ПРОЕКТИРОВАНИЯ ПРОПУЛЬСИВНЫХ КОМПЛЕКСОВ СО СРЕДНЕОБОРОТНЫМИ ДВИГАТЕЛЯМИ

The article gives an overview of the directions for the further development of software for computer-aided design systems for propulsion complexes with medium-speed engine. There has been proposed the system of CAD PC with electronic data processing based on the existing development and including the development of electronic data processing and gearbox databases, location of PC equipment on board the ship, determination of the stable dimensions of the shaft line according to the rules of the RF Register and oscillations of the console and span of the maximum length, justification of technical solutions using performance criteria. A typical scheme of computer-aided design has been considered, which includes new sections of computer-aided design with electronic data processing.

Modeling and adaptive compensation of tooth surface contour error for internal gearing power honing

The machining of high precision gears requires a strict and accurate co-movement relationship controlled by the electronic gearbox between the moving axes of the gear machine tools. This article proposes a tooth surface contour error modeling method and an adaptive electronic gearbox cross-coupling controller for internal gearing power honing. First, the electronic gearbox model is structured according to the generative machining principle of internal gearing power honing and the tooth surface contour error is established by means of homogeneous coordinate transformation and meshing principle. Then, the adaptive electronic gearbox cross-coupling controller is designed, which comprises the electronic gearbox cross-coupling controller and the fuzzy proportional–integral–derivative controllers whose universes of membership functions in fuzzy rules are optimized by particle swarm optimization to improve the adaptability and robustness to disturbance fluctuation and model uncertainty of the system. Finally, experiments are carried out on a self-developed gear numerical control system. The results have demonstrated that the estimated tooth surface contour error using the proposed method is very close to the actual one, and the proposed adaptive electronic gearbox cross-coupling controller can effectively reduce the tracking error and the tooth surface contour error when compared to the electronic gearbox cross-coupling controller and non–electronic gearbox cross-coupling controller (electronic gearbox controller without cross-coupling and adaptive compensation).

Non-circular gear continuous generating machining interpolation method and experimental research

Current non-circular gear manufacturing process all use discrete machining method, which generates a large number of small line segments, brings in approximate error, and leads to high-order discontinuity of the whole tool path curve. The tooth surface quality will be decreased significantly due to the vibration of machining tool caused by the discontinuity of machine tool motion trajectory especially in high-speed machining. In addition, the processing speed and efficiency will be limited due to the unsmooth kinematics profile. This paper proposes a non-circular gear completely continuous generating machining interpolation method. The non-circular gear machining electronic gearbox is developed to compute the real-time interpolation point data to guarantee the strict generating motion relationship between the workpiece spindle, feed shaft, and cutter spindle during the gear manufacturing process according to the derived linkage model for non-circular gear hobbing and generate continuous smooth machining trajectory. The proposed interpolation method is implemented on the self-developed CNC system based on the embedded CNC system hardware structure platform and verified experimentally on a gear hobbing machine. A pair of two-order oval non-circular gear is machined, and the roll and application experiments on a kind of gear pumps are done to illustrate the machining performance and provide a high efficiency and precision machining method for non-circular gear.

Design and analysis of the electronic helical guide controller

This paper presents an Electronic Helical Guide Controller (EHGC) for the helical gear shaping process. Considering that the pinion cutter’s reciprocating movement is driven by a crank-connecting rod mechanism in most traditional gear shaping machines, this study adopts this kind of gear shaper as the machine platform to establish an accurate mathematical model. Then, the helical guide movement control algorithm is embedded in the interpolation module of the gear shaping CNC system using the electronic gearbox techniques to realize the special multi-axis linkage control requirements of the helical gear shaping process. The crankshaft’s angular position is measured by the internal sensor, so the rotational speed could be calculated online in each interpolation control cycle. The actual position and the velocity of the shaper cutter along the Z-axis are calculated using the kinematic model of the crank-connecting mechanism, at the same time, the motion of the other axes is controlled by the electronic gearbox. The proposed EHGC is low cost and very easy to implement in practice since it does not need a linear grating ruler and a probe on the Z-axis. The gear machining accuracy can also be estimated online by the EHGC, so as to guide the selection of the process parameters and improve the production efficiency. Experiments are performed to verify the effectiveness of the proposed EHGC.

A novel gear machining CNC design and experimental research

Strict position and speed synchronization constraint relationship of the gear machine tools axes make gear machining different from the traditional multiaxis machining process. This paper proposes a reconfigurable embedded CNC system platform used for gear machine tools based on the “ARM + DSP” hardware structure. The parametric automatic programming module is introduced to generate NC machining program according to the gear parameters, cutting tool parameters, and machining process parameters automatically. The gear machining process-database module is used to support the previous function modules to optimize the cutting process cycle parameters through intelligent expert knowledge base. In order to meet the requirements of multiaxis synchronous movement, a new type of software electronic gearbox is put forward, and the implementation method of it in the CNC is also studied. To reconfigure the electronic gearbox (EGB) function and simple parameters setting, the embedded gear machining CNC system can be applied to different gear cutting machine tools, such as gear milling, shaping, hobbing, scudding, grinding, and honing machine. Finally, the proposed embedded CNC system is verified experimentally on a six-axis gear hobbing machine. All of the tracking error, contour error, and final measured results show that the proposed CNC system which has these core gear machining function modules can work effectively.

A Flexible Electronic Helical Guide Controller

In this paper, an Electronic Helical Guide Controller (EHGC) is proposed, for helical gear shaping processes. In most traditional gear shaper machines, the cutter's reciprocating movement is driven by a crank-connecting rod mechanism. Therefore, this study adopts this kind of gear shaper as the machine platform to establish an accurate mathematical model. The control algorithm is embedded in the interpolation module of the CNC system using electronic gearbox techniques to realize special multi-axis linkage control requirements. The crankshaft's angular position is measured and the rotational speed is calculated in each control cycle. The actual position and velocity of the cutter along the Z-axis can be calculated using the geometric relations of the crank-connecting mechanism, and motion in the other axes can be controlled by the electronic gearbox. A special G code with parameters (G83) is also designed and the EHGC control through NC programming is realized in an improvised gear shaping CNC machine. The proposed EHGC is low cost and easy to implement in practice since it does not need a linear grating ruler and a probe on the Z-axis. Furthermore, EHGC allows the flexibility to change a part's helix angle to compensate for distortions caused by heat treatment. Simulations and experiments are performed to verify the effectiveness of the proposed EHGC.

A motion control method for face hobbing on CNC hypoid generator

In this paper, the relative motion relation was derivated among the virtual cradle, generating gear, cutter and workpiece on the CNC hypoid generator. A directly axis coordinate solving method of CNC hypoid generator was proposed by taking cutter axis vector as control objectives to transform the attitude of whole cradle-type generator. The method didn't solve complex nonlinear equations. We also provide a motion control solution for face-hobbing on the CNC hypoid generator using Siemens 840Dsl NC system.In this method, the online real-time programming is achieved, because of the index motion and generating motion of machining process are separated, and spline interpolation and electronic gearbox function are adopted. The tooth form equation which is determined by the motion control model of CNC hypoid generator is derived. The calculation example of a gear sets shows that the theoretical tooth form of the epicycloid hypoid gear machined by such motion control method is consistent with the standard tooth form computed by Gleason CAGE Software. With NC machining simulation software VERICUT, virtual NC hypoid gear cutting machine is established, which realizes face hobbing simulation of such gear sets. At last, a face hobbing experiment is conducted on YK2235 CNC hypoid generator manufactured by Tianjin No. 1 Machine Tool Works, and such face hobbing motion control model is verified as correct through tooth form measurement and rolling test.

Precision control and compensation of helical gear hobbing via electronic gearbox Cross-Coupling controller

The gear generation process is strongly dependent on the accuracy of the multi-axis relative motion, which is controlled by the electronic gearbox (EGB). This research mainly focuses on helical gear hobbing and on EGB control error analysis, estimation and compensation in the generation process of a gear hobbing machine. First, a simple approach for estimation of the helical gear pitch error and the spiral line contour error is proposed. Then, in conjunction with this estimation method, an EGB cross-coupling controller (ECCC) architecture, which is connected by the EGB and the cross-coupling controller, is presented. Simulation results show that the proposed ECCC has higher control accuracy than an uncoupled controller, and its control accuracy can be further improved using friction compensation. Finally, experiments are conducted on an YS3118 six-axis hobbing machine. The helical gears machined using this machine have high precision. In addition, the proposed ECCC architecture can be implemented easily on most motion systems that are in current use.

A new electronic gearbox for gear hobbing machines

This article presents a new kind of software-defined electronic gearbox for gear hobbing based on a theoretical model of the hobbing process. The electronic gearbox implementation and structure are studied in an embedded numerical control system (numerical control/computer numerical control). Data flow among the electronic gearbox modules is also analyzed in the numerical control system. Special G-codes with parameters are designed, and the electronic gearbox control implemented through numerical control programming is realized in a custom gear hobbing numerical control system. In addition, two different hobbing methods (axial and diagonal) are tested on the computer numerical control platform. Results show that the hobbing computer numerical control with the proposed electronic gearbox functions accurately, and error is measured using tracking errors in different axes and gear pitch error of the machined gear. As will be shown, the gear pitch error was found to be 0.0147 mm for axial hobbing and 0.0176 mm for diagonal hobbing.

Formula One electronic gearbox control

Is changing gear really as easy as pushing a button? If you are ever in a Formula One racing car, you might find out that it is easier than you thought it is—or is it?!

The Electronic Gearbox — Computer Software Replaces Mechanical Couplings

Recent work on eliminating the disadvantages of mechanical couplings has resulted in important new developments in real-time computer software. This result is the most recent development in work initiated by J. Loxham aimed at replacing the function of mechanical gearboxes with electrical actuators controlled in a low-error servo loop to provide the function of a high-performance gearbox but without the inevitable disadvantages of mechanical couplings. It is believed to be the first practical example of the application of CNC to continuous motion as opposed to point-to-point movement. The paper describes the Cranfield “electronic gearbox” which provides, either in software or hard-wired form, a higher level of performance than can be obtained from its mechanical counterpart. The electronic gearbox has been applied successfully to gear grinding and gear hobbing machines, and in each case the machine's performance has exhibited higher precision, higher productivity, and increased reliability, with the prospect of a lover capital cost since the prices of microprocessors and electronic components are falling in real terms.