1、 Machinery
1. Gear transmission:
1) Classification: plane gear transmission, space gear transmission.
2) Features:
A advantages: wide range of applicable circumferential speed and power; accurate transmission ratio, stability, high efficiency; high reliability and long service life. It can realize the transmission among parallel shaft, any angle intersecting shaft and any angle staggered shaft
b) Disadvantages: high manufacturing and installation accuracy, high cost. It is not suitable for long distance transmission between two shafts.
c) The names of the basic dimensions of involute standard gears are: addendum circle; dedendum circle; graduation circle; die number; pressure angle, etc.
2. Turbine scroll rod transmission: it is suitable for the motion and power between two vertical and non intersecting shafts.
1) Features: advantages: large transmission ratio. The structure is compact.
2) Disadvantages: large axial force, easy heating, low efficiency. Only one way transmission.
3) The main parameters of turbine worm rod drive are: modulus; pressure angle; worm gear indexing circle; worm indexing circle; lead; number of worm gear teeth; number of worm head; transmission ratio, etc.
3. Belt drive: including driving wheel, driven wheel and annular belt
1) The concept of opening motion, center distance and wrap angle is used when two axes are parallel and the rotation direction is the same.
2) According to the cross-sectional shape, the belt can be divided into three types: flat belt, V-belt and special belt.
3) The key points of application are: the calculation of transmission ratio; the stress analysis and calculation of belt; the allowable power of single V-belt.
4) Characteristics of belt drive:
A advantages: it is suitable for the transmission with large center distance between two shafts; the belt has good flexibility, which can ease the impact and absorb vibration; it can slip when overload to prevent damage to other parts; it has simple structure and low cost.
B disadvantages: the overall size of the transmission is large; the tension device is needed; the fixed transmission ratio cannot be guaranteed due to slipping; the service life of the belt is short; the transmission efficiency is low.
4. Chain drive includes: driving chain, driven chain and ring chain.
Compared with the instantaneous transmission chain, it has the advantages of low transmission speed and center distance, and is not easy to manufacture.
5. Gear train:
1) There are two types of gear trains: fixed axle gear train and epicyclic gear train.
2) The ratio of the angular velocity (or speed) of the input shaft and the output shaft in the gear train is called the transmission ratio of the gear train. It is equal to the ratio of the product of the number of teeth of all driven gears and the product of the number of teeth of all driving gears.
3) In epicyclic gear train, the gear whose axis position changes, that is, the gear that makes both rotation and revolution, is called planetary gear, while the gear whose axis position is fixed is called center gear or sun gear.
4) The transmission ratio of epicyclic gear train can't be calculated directly by solving the transmission ratio of fixed axle gear train. The principle of relative motion must be used to convert epicyclic gear train into imaginary fixed axle gear train by using relative velocity method (or reverse method).
5) The main features of the gear train are: it is suitable for the transmission between two shafts far apart; it can be used as a transmission to realize variable speed transmission; it can obtain a larger transmission ratio; it can realize the synthesis and decomposition of motion.
2、 Electrical:
1. High accuracy: servo motor as power source, composed of ball screw and synchronous belt, simple structure and high efficiency transmission mechanism. Its repeatability error is 0.01%.
2. Energy saving: the energy released in the deceleration phase of the working cycle can be converted into electrical energy for reuse, thus reducing the operating cost. The connected electrical equipment is only 25% of the electrical equipment required for hydraulic drive.
3. Precision control: according to the set parameters to achieve accurate control, with the support of high-precision sensors, metering devices, computer technology, it can greatly exceed the control accuracy of other control methods.
4. Improve the level of environmental protection: due to the reduction of energy varieties and their optimized performance, pollution sources and noise are reduced, which provides a better guarantee for the environmental protection of the factory.
5. Noise reduction: its operating noise value is less than 70 dB, which is about 2 / 3 of the noise value of the hydraulic driven injection molding machine.
6. Cost saving: This machine eliminates the cost and trouble of hydraulic oil, no hard pipe or soft throat, no need to cool the hydraulic oil, greatly reducing the cost of cooling water, etc.
3、 Air pressure
1. Advantages:
1) With air as the working medium, the working medium is easy to obtain, and the used air is discharged into the atmosphere, which is easy to handle. Compared with hydraulic transmission, there is no need to set the recovery oil tank and pipeline.
2) Because the viscosity of air is very small (about one ten thousandth of the dynamic viscosity of hydraulic oil), its loss is also very small, so it is convenient for centralized gas supply and long-distance transportation. The external leakage will not pollute the environment as seriously as the hydraulic transmission.
3) Compared with the hydraulic transmission, it has the advantages of simple operation, quick reaction and quick maintenance.
4) Good adaptability of working environment, especially in flammable, explosive, dusty, strong magnetic, radiation, vibration and other harsh working environment, superior to hydraulic, electronic and electrical control.
5) Low cost, automatic overload protection.
2. Disadvantages
1) Due to the compressibility of air, the stability of working speed is slightly poor. However, the pneumatic hydraulic linkage device can achieve satisfactory results.
2) Because of the low working pressure (generally 0.31.0mpa) and the structure size should not be too large, the total output should not be greater than 10-40kn.
3) The noise is big, so the muffler should be added when exhaust at high speed.
4) The speed of pneumatic signal transmission in pneumatic device is slower than that of electron and light within the speed of sound, so pneumatic control system is not suitable for complex circuit with too many components.
4、 Hydraulic pressure
1. Advantages
1) From the structure point of view, the output power per unit weight and per unit size of the four types of transmission are superior to each other, and have a large moment inertia ratio. In the case of transmitting the same power, the hydraulic transmission device has the advantages of small volume, light weight, small inertia, compact structure and flexible layout.
2) From the performance point of view, speed, torque, power can be stepless adjustment, fast response, can quickly change direction and speed, wide speed range, speed range up to 100:1 to 2000:1; fast action, control, regulation is relatively simple, easy to operate, labor-saving, easy to cooperate with electrical control, and with the CPU (computer) connection, easy to achieve automation.
3) In terms of use and maintenance, the components have good self lubrication, easy to realize overload protection and pressure maintaining, and are safe and reliable; the components are easy to realize serialization, standardization and generalization.
4) All the equipments with hydraulic technology are 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 process. The manufacturing cost of hydraulic components is relatively low, and the adaptability is relatively strong.
6) It has become the trend of world development to combine hydraulic with microcomputer control and other new technologies to form the integration of "mechanism electricity hydraulic light".
2. Disadvantages:
Everything is divided into two parts, hydraulic transmission is no exception: 1) because of the relative movement of hydraulic transmission, the surface inevitably has leakage, and the oil is not absolutely incompressible, coupled with the elastic deformation of oil pipe, hydraulic transmission can not get a strict transmission ratio, so it can not be used in the in-line transmission chain of machine tools such as processing screw gear.
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.
3) Under the condition of high temperature and low temperature, it is difficult to use hydraulic transmission.
4) As well as to meet the manufacturing and maintenance of some hydraulic components on the high accuracy requirements.
5) It is difficult to check the fault, especially in the units where the hydraulic technology is not popular. This contradiction often hinders the further promotion and application of hydraulic technology. The maintenance of hydraulic equipment needs to rely on experience, and it takes a long time to train hydraulic technicians.
