Views:159 Author:Cardan Shaft Manufacturer Publish Time: 2019-02-06 Origin:Sitong Cardan Shaft Co.,Ltd
Cardan shaft is like finished dish. Today we will talk about how to make the dish of drive shaft.
The first question, which industrial cardan shaft do we cook today? Is it long or short, thick or thin, iron or stainless steel? So the first thing we face is to choose cardan shaft.
Drive shaft selection
Take selection of coupling shaft for engine bench test as an example. 1. Since the drive shaft for the whole vehicle is connected by gearbox, and the actual use of car on road, its working state (rotation speed, torque, vibration, etc.) is very different from the bench test. Use of the test is much worse. 2. Drive shafts for vehicles are usually long and have great limitations in installation and are not suitable for use in bench tests. Therefore, drive shaft for the bench test must be customized for the bench test.
The design and purchase of the drive shaft for gantry (especially for high-power diesel engines) must pay attention to the following points:
1. It must be considered to add a high-elastic coupling, mainly used to eliminate the torsional vibration caused by different moments of inertia of the engine and dynamometer.
2. Since the vibration caused by high-power diesel engine is large in bench test, in order for the test to proceed smoothly, a device must be used to absorb vibration. Based on practical experience, it is recommended to make improvements on the engine mount and suspension, and no hard connections can be made.
3. As engine mount changes, amplitude of engine increases, that is, dynamic relative displacement of engine's central axis relative to center axis of dynamometer increases.
According to this working condition, we must choose a transmission shaft that can eliminate this asymmetry. At least four types of propeller shafts can meet this condition, the most common being the universal joint drive shaft. The biggest advantage of the universal joint shaft is the large amount of angular displacement compensation. But there are also disadvantages. It will produce motion reaction force, will amplify system vibration (like spring), and the noise is large, etc. So if the central axis angle is not large, you can try not to use universal joint shaft. It can adopt elastic shaft with two ends and can compensate for a certain angle and axial displacement. It is not only light weight, but also maintenance-free and has low noise. If the angle is large, it is necessary to use universal joint shaft, it is best to use it with high-elastic coupling, which is beneficial to improve torsional vibration and reduce impact. Moreover, the coupling preferably has a built-in bearing device to ensure sufficient axial and radial motion reaction forces of the cardan shaft. For the test bench with higher noise and vibration requirements, carbon fiber shafting can be used, of course, the price is higher. In general, diesel rigs use high-elastic couplings. Moreover, it is mainly necessary to consider vibrations in low speed range. Because the resonance range of this power system is closer to low speed. The stiffness of coupling generally has two characteristics, one is that stiffness is constant, that is, stiffness does not change with load (rotation speed); There is also a coupling in which the stiffness varies with load (speed). For heavy-duty applications, CF-R couplings can be used. This product has characteristics that vary with load (speed). At low speeds and low loads, the elasticity is very high and the resonance interval can be adjusted. The ability to adapt to heavy-duty conditions is very strong. Generally rely on the diesel engine. Because vibration on diesel side is significantly higher than that on dynamometer, and temperature on diesel side is relatively higher. In addition, it has a lot to do with what kind of coupling you choose. If your coupling does not have a built-in bearing and engine is elastically supported, the dynamic displacement will also generate a large amount of vibration energy, which will accelerate the damage of elastic parts. Due to the "congenital" drawback of the engine - the torque is pulsating, a flexible coupling is usually required. Dangerous torsional resonances must be avoided. For flexible couplings, the "main resonance" speed (determined by the first mode frequency and the main harmonic) must be lower than the operating speed. In this device, the elastic coupling mainly functions as torque compensation and torsional vibration isolation. The cardan shaft and similar devices act as misalignment and relative "movement" of the axis, and the compensation capability depends on the spacing of the two joints.
The next step is cooking method. Is it braised or steamed, is the fire stir-fried or slow, is it a sweet drive shaft or a salty drive shaft. Every detail needs to be carefully considered. The end coupling form of drive shaft is cooking method we choose.
Drive shaft is an important component of transmission system that transmits power. The end of the drive shaft is connected in various forms and has different characteristics. The design of the drive shaft is suitable for the reliable transmission of power. Therefore, a reasonable choice of the end form of the drive shaft is an important aspect to consider in the design.
The only function of the end coupling is to transmit torque. They should have a good centering of the drive shaft and couple the input and output shafts via the drive shaft by friction or rigidity, or a combination of both. There are five possible practical forms of coupling drive shafts:
1. Flange. The end of drive shaft is coupled by a flange with an ear fork, which is a widely used coupling form due to its simple structure, easy manufacture and assembly. According to the centering method, there are two kinds of inner centering and outer centering; according to different ways of transmitting force, there are points of rigid transmission and friction transmission.
2. Slotted fork. The end of drive shaft is coupled to hub, hub is slotted, locked when closed, loosened when opened, used in agricultural machinery, and splined hub that can be quickly separated has been standardized.
3. Spline half shaft. A drive shaft with a single universal joint or a double joint, the ends of which are connected by keys or splines on two shafts, steering axle being used in this form.
4. Airfoil bearing. The end of drive shaft is coupled by two assemblies with small wing bearings and can be replaced as a combination, which is often used in construction machinery.
5. End yoke. The end is a yoke, connected to coupled piece by cross shaft. The cross shaft of driving shaft end is installed in sleeve, and sleeve on cross shaft is fixed by u-bolt in two semicircular grooves of end of driven shaft, and sleeve is centered.
The main drive shaft of construction machine uses flanges or wing bearings for end connection. The choice of end form of drive shaft should be considered:
1. Transfer torque balance
The neutrality of end form affects the balance of transmitted torque. The flanged drive shaft runs smoothly by adjusting the axial clearance of the bearing assembly and with precise, free centering. Slotted forks and splined half shafts are connected to the center of the input shaft and the output shaft. Due to manufacturing tolerances, the centering of the shaft is off-center and the balance of the drive shaft is also reduced. The case where the wing bearing and the u-bolt are coupled is similar to the slotted fork, and since the axial clearance of the cross shaft is not adjustable, a high level of balance quality is not achieved.
2. Torque transmission reliability
The design calculations for the end joints are either calculated according to stiffness transfer or calculated by friction transfer, which should not be counted at the same time. Friction transmission is affected by dispersion of friction coefficient. It is not easy to accurately design connection parameters according to transmission torque. For safety reasons, conservative design is adopted and the structure is too large. The rigid transmission is transmitted by a flat key or a spline, and transmission torque is larger and more reliable, so that rigidity transmission is superior to friction transmission when transmitting a large torque.
3. Other factors
The end connection form should also consider other factors such as layout space, supporting supply, cost and so on.
The working angle is equivalent to the heat.
1. The working swing angle is theoretically less than 90°, because the simplest rigid body kinematics shows that when the swing angle of the universal joint is 90 degrees, it is just the dead point of the steering transmission mechanism and cannot be driven.
2. The drive shaft is a high-speed, low-supporting rotating body, so its dynamic balance is crucial. Generally, drive shaft must be tested for dynamic balance before leaving factory and adjusted on the balancer. For front-engine rear-wheel drive car, rotation of transmission is transmitted to main reducer shaft, which can be several sections, and joints can be connected by a universal joint.
3. In physics, an angle variable introduced to study the motion law of a pendulum in a simple harmonic motion. The angle between the cycloid and vertical direction is called swing angle. The swing angle is generally a variable introduced to study the energy conversion process in simple harmonic motion. The kinetic energy and potential energy of ball can be measured by the size of swing angle, and speed of ball at any position can be measured. Specifically, swing angle refers not only to angle of variable formed by single pendulum, but as long as it has the same mechanical motion as the pendulum and conforms to simple harmonic motion law, corresponding angle variable can be regarded as the swing angle.
Select right drive shaft, appropriate end connection form, appropriate swing angle size in order to make drive shaft delicious.
If you are still confused, you can contact us.