No powertrain is perfect.
Among the four major types of transmission methods (mechanical, electrical, hydraulic and pneumatic), none of the power transmissions is perfect.
Mechanical transmission
1. Gear transmission
Including: face gear transmission, space freighter transmission Advantages:
Suitable for a wide range of peripheral speed and power
Transmission ratio is accurate, stable and efficient
High working reliability and long service life
. Transmission between parallel shafts, intersecting shafts at any angle and staggered shafts at any angle can be realized Disadvantages:
Requires higher manufacturing and installation precision: 4
higher cost,
It is not suitable for long-distance transmission between two shafts.
The names of the basic dimensions of involute standard gears include addendum circle, dedendum circle, indexing circle, modulus, pressure angle, etc.
2. Turbine worm drive
Applicable to motion and dynamics between two axes whose spaces are perpendicular but not intersecting
advantage:
large transmission ratio
Compact size
shortcoming:
large axial force,
prone to fever;
low efficiency;
Only one-way transmission
The main parameters of the worm gear drive are:
Modulus:
pressure angle:
Worm gear indexing circle
Worm pitch circle
Lead
number of worm gear teeth,
number of worm heads;
Transmission ratio etc.
. belt drive
Including: driving wheel, driven wheel, endless belt
It is used in the occasion where the two parallel axes rotate in the same direction. It is called opening movement, the concepts of center distance and wrap angle. The type of belt can be divided into three categories: flat belt, V belt and special belt according to the shape of the cross section.
The focus of the application is: the calculation of the transmission ratio: the stress analysis and calculation of the belt; the allowable power of a single V-belt Advantages:
Suitable for transmission with a large center distance between two shafts:
The belt has good flexibility to cushion shock and absorb vibration:
Slip to prevent damage to other important parts when overloaded: 0
Simple structure and low cost
shortcoming:
The outer dimensions of the drive are larger;
Required tensioning device:
Due to slippage, a fixed transmission ratio cannot be guaranteed:
belt life is shorter
low transmission efficiency
4. Chain drive
Including: driving chain, driven chain, ring chain
Compared with the gear transmission, the main characteristics of the chain transmission
Manufacturing and installation precision requirements are low;
When the center distance is large, the transmission structure is simple
The instantaneous chain speed and instantaneous transmission ratio are not constant, and the transmission stability is poor
5. Wheel train
The gear train is divided into two types: fixed axis gear train and epicyclic gear train
The ratio of the angular velocity (or rotational speed) of the input shaft to the output shaft in the gear train is called the transmission ratio of the gear train. Equal to the ratio of the product of the teeth of all the driven gears to the product of the teeth of all the driving gears in each pair of meshing gears
In the epicyclic gear train, the gear whose axis position changes, that is, the gear that rotates and revolves, is called a planetary gear. The gear with a fixed axis position is called a sun gear or a sun gear.
The transmission ratio of the epicyclic gear train cannot be directly calculated by solving the transmission ratio of the fixed axis gear train. The principle of relative motion must be used to convert the epicyclic gear train into an imaginary fixed axis by using the relative speed method (or called the inversion method). Wheels are calculated.
The main features of the wheel train:
Suitable for transmission between two shafts that are far apart:
Can be used as a transmission to realize variable speed transmission:
A larger transmission ratio can be obtained;
Realize the synthesis and decomposition of motion.
Electric drive
high precision
The servo motor is used as the power source, and the transmission mechanism with simple structure and high efficiency is composed of ball screw and synchronous belt. Its repeatability error is 0.01%.
2. Save energy
The energy released during the deceleration phase of the working cycle can be converted into electrical energy for reuse, thereby reducing operating costs, and the connected electrical equipment is only 25% of the electrical equipment required for hydraulic drive.
3. Jingke Control
Accurate control is realized according to the set parameters. With the support of high-precision sensors, metering devices, and computer technology, it can greatly exceed the control accuracy that other control methods can achieve.
Improve environmental protection
4. Due to the reduction of energy types and its optimized performance, the sources of pollution are reduced and the noise is reduced, which provides a better guarantee for the environmental protection of the factory.
5. Reduce noise
Its operating noise value is lower than 70 decibels, which is about 213.5% of the noise value of hydraulically driven injection molding machines.
6. Cost saving
This machine eliminates the cost of hydraulic oil and the troubles caused by it. There is no hard pipe or soft pipe, no need to cool the hydraulic oil, and the cost of cooling water is greatly reduced.
Hydraulic transmission
advantage :
1. From a structural point of view, its output power per unit weight and output power per unit size are overwhelming among the four types of transmission methods. It has a large moment-to-inertia ratio. Under the condition of transmitting the same power, the volume of the hydraulic transmission device Small size, light weight, low inertia, compact structure, flexible layout
2. From the perspective of work performance, the speed, torque and power can be adjusted steplessly, the action response is fast, the direction can be changed quickly and the speed can be changed quickly, the speed adjustment range is wide, and the speed adjustment range can reach 100: to 2000:1. Rapid action Well, the control and adjustment are relatively simple, the operation is relatively convenient and labor-saving, and it is convenient to cooperate with the electrical control and to be connected to the CPU (computer), which is convenient for realizing automation.
3. From the point of view of use and maintenance, the self-lubricating properties of the components are good, and it is easy to realize overload protection and pressure maintenance. The safe and reliable components are easy to realize serialization, standardization and generalization.
4. All equipment using hydraulic technology is safe and reliable
5. Economy: The plasticity and variability of hydraulic technology are very strong, which can increase the flexibility of flexible production, and it is easy to change and adjust the production procedure. The manufacturing cost of hydraulic components is relatively low, and the adaptability is relatively strong.
6. The combination of hydraulic pressure and new technologies such as microcomputer control to form the integration of “mechanical-electrical-hydraulic-optical” has become the trend of world development, which is convenient for digitalization.
shortcoming:
Everything is divided into two, and hydraulic transmission is no exception.
1. Hydraulic transmission inevitably leaks due to the relative moving surface. At the same time, the oil is not absolutely incompressible. In addition to the elastic deformation of the oil pipe, the hydraulic transmission cannot obtain a strict transmission ratio, so it cannot be used for machine tools such as processing threaded gears. in the inline drive chain of
2. There are edge loss, local loss and leakage loss in the process of oil flow, and the transmission efficiency is low, so it is not suitable for long-distance transmission
Under high temperature and low temperature conditions, it is difficult to adopt hydraulic transmission
3. The noise is loud, and a muffler should be added when exhausting at high speed
4. The gas signal transmission speed in the pneumatic device is slower than the speed of electrons and light within the speed of sound. Therefore, the pneumatic control system is not suitable for complex circuits with too many components.
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