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  • In the design of the transmission, it was necessary to consider a large number of operating parameters in the design and determination of the size of the design, allowing the power geometry boundary and position relationship, speed ratio data and many other parameters to be determined. When determining the size of the reducer shaft, the transmitted torque, the bending stress and the lateral force appear, taking into account the stress concentration in the hazardous area accordingly, all play a decisive role in the calculation. For rolling bearing calculations, the dimensions should be included in the application's required life limits and space limits.

    Today, the transmission of technical components, such as gear reducer, requires light weight, reducer structure is firm, high power density, reducer components long life. From the single-piece production of the gear unit to the large number of reducer series, it is required that the individual system components be accurately evaluated at the planning stage, and these components must be operated without trouble under different installation conditions and operating conditions. In the development phase, this type of complex system is increasingly using digital simulation method to study.

    In order to identify the static, especially the dynamic limit of the relationship between the mechanical transmission technology in the establishment of a simulation model, which in modeling efforts to try to draw as much as possible the actual system. The actual calculation model of the drive system only represents an abstract concept. In addition to finding the deformation relationship and displacement in the gear meshing, a computational model was established, in particular, for the analysis of dynamic performance, which sets out the following points: Cost savings and time savings in new development or optimization by dynamic simulation.

    (1) to clarify the questions raised (resonance, shaft or box breakage, noise, etc.).

    Determine the best parameters related to the predetermined limit (eg, energy consumption stiffness limit rotational speed structural space, noise radiation, etc.).

    In order to meet the growing market demand, in recent years, SKF has carried out a lot of software development work, which special attention to the development of both for the development of rolling bearings, but also for the system description of the model software and simulation software. One of the packages developed by SKF for complex system modeling and simulation is the Orpheus program, which is a set of modeling and simulation programs that best approximate the actual operating conditions.

    With this software package, it is possible to achieve the planning tasks of analyzing the static and dynamic performance of the entire part or machine (eg gearboxes including gears, axle housing and rolling bearings).

    In order to be able to provide the expertise and technical capabilities of SKF engineers to all users, a business unit that provides computing technology services for SKF customer circles in the name of "SKF Engineering Consulting Services" has been established. The focus of the service is on modeling and modeling of engineering applications and static and dynamic performance simulations. The preferred range of applications is a cylindrical gear reducer or a planetary gear unit, a compressor, a pump, a motor or an entire transmission circuit which, when summarized in the problem, in terms of defect analysis of deformation characteristics or noise and vibration performance, or in order to optimize the system, To carry out the study precisely.

    218K reducer program prototype to participate in the 2003 Hannover Industrial Fair by SKF's different departments to optimize the 18K reducer program prototype (), that its design process.

    The 18K reducer prototype was built on a 280-gauge gear reducer, constructed and analyzed in detail, and the center distance was reduced to 250 mm at the same speed ratio and power data. Of the components and the new power density to match, and to achieve the required system life of more than 5000h, it is necessary to re-calculate the reducer single parts. In addition to the new, higher carrying capacity of SKF bearings, that is, the average load capacity increased by 15% of the flexibility characteristics, deformation characteristics and component load digital simulation, the reducer analysis.

    In the modeling, all parts of the gearbox housing are considered, the shafts are engaged with the bearings and the individual gears are engaged. The difficulty in modeling is a detailed description of the rolling bearing, taking into account the bearing in the preload, bearing clearance, temperature and other operating parameters and the occurrence of deflection. Manufacturing deviations (such as assembly or orientation errors, non-roundness of bearing fit) can be modeled in principle, but are not taken into account in the study.

    The original box design can be very fast to build the three-dimensional model of the box (). The model is entered into the commercial finite element software "ANSYS * program, which is inserted into a single node (the outer bearing of the rolling bearing) description, and is connected into a box grid ().

    The lattice structure is generally a lot of data, often due to the processing time is too long, not applicable to the actual analysis. Thus, in order to further handle the box structure, a smart compression technique called CMS (component modal synthesis) is used, thereby significantly reducing the number of degrees of freedom. In this method, The deformation field is described by the corresponding shape function, and the shape function should be chosen so that they satisfy the boundary condition.

    With this method, the deformation can be calculated, and the vibration mode in the wide frequency range is naturally obtained. As a basic structure for further calculation, the deceleration including all the components is shown. In addition to calculating the core, the Orpheus program also provides the purpose of animating and visualizing the possibility. The deformation performance of the structure or the dynamic performance of the application can be graphically processed in this way (or), or viewed as a video presentation. The comparative observation data for the different structures or schemes can be listed and evaluated. Possible optimization measures, and their impact on the stiffness changes associated with factors such as enclosure structure, bearing selection and bearing arrangement, can be virtually modeled in a computer.

    3 Summary In order to evaluate and optimize the prototype of the 18K reducer program within the scope of the 18K project, the following data are obtained: all contact stress distributions in a single rolling bearing.

    One by one bearing inside and outside the seat between the tilt.

    One by one in accordance with ISO281131 calculated by a single rolling bearing to modify the nominal bearing life.

    The identification of vibration characteristics and possible reduction of the main characteristic noise source of the gear unit is not the object of the optimization measure.

    The power of the reducer unit prototype 18K is comparable to that of the large-scale 280 reducer currently used in the industry. However, compared with the basic model, the weight is reduced by 15% to 2%, the size is reduced by 1 to 20% 10% to 13%. The large number of applications with the limited number of methods associated with the SKF program Orpheus make it possible to perform detailed analysis of the static and dynamic performance of all the transmission parts of the overall reducer system.

  • According to the different characteristics of the reducer can be divided into different types of reducer. Common reducer includes: worm gear reducer; planetary reducer; harmonic reducer. Enterprises can choose according to the needs of different reducer different types.

    First, the type of common reducer

    1, Harmonic gearbox harmonic transmission is the use of flexible components to control the elastic deformation to transfer movement and power, the volume is not large, high precision, but the disadvantage is the limited life of the flexible wheel, impatience impact, rigidity and metal parts Compared to poor, the input speed can not be too high.

    2, planetary reducer The advantages of the structure is relatively compact, small return gap, high precision, long life, rated output torque can be done very large. But the price is slightly expensive.

    3, worm gear reducer is characterized by a reverse self-locking function, you can have a larger reduction ratio, the input shaft and output shaft is not on the same axis, nor in the same plane. But the general size is larger, the transmission efficiency is not high, the accuracy is not high.

    Second, the role of reducer

    1, speed at the same time reduce the load inertia, inertia to reduce the square of the reduction ratio. We can look at the general motor has an inertia value.

    2, slow down at the same time improve the output torque, torque output ratio by motor output multiplier, but be careful not to exceed the reducer rated torque.

    General gear reducer with helical gear reducer including parallel shaft helical gear reducer, worm gear reducer, bevel gear reducer, etc., planetary gear reducer, cycloid reducer, worm gear reducer, planetary friction machine Class gear and so on.

    The reducer is generally used for low-speed and high-torque transmission equipment, the motor. Internal combustion engine or other high-speed operation of the power through the reducer on the input shaft teeth less gear meshing the output gear on the gear to achieve the purpose of deceleration, Reducer will have several pairs of the same principle gear to achieve the desired deceleration effect, the size of the gear ratio of teeth, is the transmission ratio.

  • 1, talk about the main difference between AC and DC motor:

    Brushless DC motor, the stator is a rotating magnetic field, dragging the rotor magnetic field rotation;

    AC synchronous motor, but also stator rotation magnetic field dragged rotor magnetic field rotation;

    So from the principle, brushless DC motor, AC synchronous motor What is the difference? In the case of

    The difference is that the rotation of the magnetic field is different for different reasons:

    (1) AC synchronous motor, the stator magnetic field rotation is 120 degrees behind each other three-phase symmetrical AC, stator magnetic field rotation is the change of AC speed;

    (2) DC motor, DC power supply is a constant constant voltage, and the actual connection of the coil connected to the formation of the change, and the actual connection with the coil to change the location of the rotor rotation speed;

    In this way, their speed control method is different:

    (1) AC synchronous motor, the stator magnetic field rotation is 120 degrees behind the three-phase symmetrical alternating current, stator magnetic field rotation is the exchange of changes in speed; as long as the change in AC change speed, you can change the motor speed, speed;

    (2) DC motor, DC power supply constant constant voltage, and the actual connection of the coil connected to the formation of the change, and the actual connection with the coil changes only with the speed of rotation of the rotor; as long as the speed of the rotor can change the speed , While the rotor speed and voltage is proportional to change the voltage can change the speed, that is, voltage regulation;

    Therefore, the DC motor, asynchronous motor speed method is different, is the structural problem, is the rotation principle of the problem;

    * 2, DC motor and asynchronous motor is the fundamental difference between the DC power supply and the coil position depends on the rotor rotation changes, only with the rotor rotation related to the signal to change the DC power supply and the coil position relationship is to achieve speed control of the core issues;

    Some people will say that the exchange speed is speed, DC speed is speed, who are the same speed. In the case of

    Answer: not the same, DC speed does not change the nature of the motor load, and the exchange speed to change the nature of the load; that is, the frequency is different, the AC motor resistance to different sizes. When the voltage is different, the resistance of DC motor does not change;

    Some people will say that what is the relationship? In the case of

    The relationship between the great, AC speed, frequency, load nature changes, is a very unstable system. DC speed, load nature of the same, is a very stable system;

    Some people will say that what is the relationship? In the case of

    Relationship is very large, exchange speed, due to instability, it is difficult to achieve fine speed. The relationship is very large, DC speed, due to stability, it is easy to achieve fine speed, a few millivolts of voltage speed can be resolved. In the case of

    3, all the motor, torque is the rotor magnetic field and the stator magnetic field interaction generated;

    Different motor, magnetic field movement in different ways, the rotor speed and magnetic field velocity is different. In the case of

    (1) AC asynchronous motor, stator rotation magnetic field and rotor rotation magnetic field synchronous interaction to produce torque, rotor speed and magnetic field asynchronous;

    (2) synchronous AC motor, the stator rotating magnetic field and the rotor rotating magnetic field synchronous interaction to produce torque, rotor speed and magnetic field synchronization;

    (3) rotating armature DC motor, stator magnetic field and rotor magnetic field interaction to produce torque, magnetic field does not move, rotor armature rotation;

    (4) Brushless DC motor, the stator rotating magnetic field interacts with the rotor rotating magnetic field to produce torque, rotor speed and magnetic field synchronization;

    4, asked: we exchange the synchronous motor rotor stator as the stator, the stator three-phase winding for the rotor, three-phase AC through the slip ring into the three-phase winding, the AC synchronous motor rotor armature rotation, stator magnetic field and rotor magnetic field The synchronous interaction produces the torque, the rotor magnetic field and the stator magnetic field do not move;

    I would like to ask, this synchronous AC motor, but also "is the stator magnetic field and the rotor magnetic field interaction generated, but the two magnetic fields are not moving. Rotation is the armature, the armature of the magnetic field does not rotate," how it is not DC motor! You say "DC motor and AC motor essential difference" is "two magnetic fields are not moving.

  • Due to the limitations of DC speed and the superiority of AC speed control, as well as the continuous development of computer technology and power electronic devices, asynchronous motor frequency control technology is rapidly developing. After nearly 10 years of application development, AC asynchronous motor frequency control performance has been comparable with the DC speed control system.

    At present, a wide range of research and application of asynchronous motor frequency control technology with constant voltage ratio control, vector control, direct torque control. In this paper, the use of asynchronous motor vector control speed control technology, with fast dynamic response, low speed performance and wide speed range and so on.

    The vector control idea is to control the AC motor model equivalent to the DC motor model. Using the coordinate transformation theory, the nonlinear and strongly coupled AC motor model is decoupled and the AC motor stator current vector is decomposed into two components: the excitation current component , Torque current component. By controlling the two vectors separately, the control of the magnetic field and the torque is realized separately.

    In this paper, a rotational speed and magnetic field closed-loop vector control system with torque inner loop is designed. The dynamic response capability of the system is fast and the anti-interference ability is strong. The torque inner loop helps to improve the decoupling performance of the speed and the closed-loop control system.

    Simulation software is used to simulate the vector control system using MATLAB software SIMULINK. The simulation results show the rationality of the design.

  • Two effects, one is the role of damping the power system to play the role of damping, the second is the stator winding negative sequence current generated by the reverse rotation of the magnetic field generated in the rotor induced current to provide access. The damping windings consist of damped teeth and damp strips forming a squirrel cage similar to an asynchronous motor. The principle is very simple is that once the stator magnetic field and the rotor magnetic field has a relative movement, will be generated in the squirrel cage induced current, the formation of additional magnetic field (from the damping effect).
  • General large and medium synchronous motor rotor, in addition to the excitation winding, but also equipped with damping winding. The damper winding is similar to the cage winding structure of the rotor of the cage type asynchronous motor. The whole damper winding consists of copper rods and short-circuit copper rings welded in the pole hole. The damping winding has two main functions:

    (1) When the synchronous motor is started asynchronously, the asynchronous motor generates the asynchronous starting torque by using the induced current in the damper winding and the stator rotating magnetic field as the cage type asynchronous motor to start the synchronous motor. So that the damper winding is the starting winding.

    (2) the relative movement between the rotor and the rotating magnetic field occurs when the synchronous motor is oscillating in the operation of the synchronous motor, and the induced current is generated in the damper winding, which interacts with the rotating magnetic field to produce a torque which prevents the rotor from rotating relative to the rotating magnetic field, Of the shock, which is the "damping" meaning.

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