This paper discusses the selection principle of co

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With the development of science and technology, social products have also begun to tend to diversified development, the product renewal cycle has been continuously reduced, the proportion of product mass production has begun to increase, and the processing requirements for products have become higher and higher. Now the traditional processing equipment has been unable to meet the needs of Society for complex and diversified products, Therefore, high-precision and high-efficiency automatic production equipment CNC machine tool was born. The electrical control performance of the data machine tool depends on the electrical control mode of the data machine tool. Therefore, the machine tool is essentially a device that converts the electromechanical capacity. Its main function is to convert the electrical energy into the mechanical energy required by the machining process of the machine tool

this paper mainly focuses on the control electrical apparatus of CNC machine tools, and interprets the electrical principle of CNC machine tools in relevant analysis and discussion, so that it looks more clear. They are clear on the basis of research on more than 20 technical indicators, such as the chemical composition of ultra free cutting materials, ultra easy cutting performance, pen factory production requirements, etc

1. Brief introduction to the electrical control of CNC machine tools

CNC machine tools are equipment that need long-term continuous operation. Therefore, in practical application, the reliability requirements of CNC machine tools are relatively high. Therefore, in the selection of electrical control system design and components, fault-tolerant technology and redundancy technology should be fully used, and reliability technology should be the basis and guarantee. At the same time, on this basis, it should also be required to have the characteristics of progressiveness. For example, in the new development of some electrical components, it is learned from the analysis of the inspection chart of PC global supply side in the second quarter of 2018 that the combined functions and the use of information electronic appliances, as well as the use of power electronic power devices. It is required that the selected components must be the most mature products that can meet relevant national standards and have relevant authorization and certification. In addition, the electrical control system must have certain maintainability, stability and safety, humanized operation, and good control characteristics

2. Selection of control appliances in the electrical control of CNC machine tools

2.1 selection of relays

relays are the electrical components of the control circuit that need to be connected or disconnected through the change of input signals. The physical quantities such as voltage, current, temperature and pressure are usually input into the relays, while the corresponding contact actions are output. The general relay selection principle requires that the type of relay shall be selected according to the specific environment to be used, and then the type of relay shall be determined according to the characteristics of the input signal, or the corresponding parameters can be input to select it. Different capacity and type of relay can be selected mainly according to the load. Relays with different structural features and principles of action require completely different input signals in nature. For example, thermal relays operate through thermal effects, while biological relays operate through sound effects. Therefore, users are required to select relay types according to the nature of input signals

2.2 selection of transformers

transformers are electrical appliances that convert a certain value of AC voltage into different values of AC voltage. The specific types of transformers are as follows: A. three-phase transformers. Generally, in three-phase AC systems, the change of three-phase voltage can be realized by using three single transformers or one three-phase transformer. Therefore, it is necessary to optimize the selection of three-phase transformers, In CNC machine tools, the three-phase transformer mainly supplies power to the drive service system; b. The machine tool control transformer is generally applicable to circuits with a frequency of 50 to 60 Hz and an input voltage lower than 660 V. It is usually used as the power control and stepping motor driver of general electrical appliances in various machine tools and mechanical equipment, as well as the power supply of indicator lamp voltage and local lighting. The selection principle of transformer mainly includes: a. the selection principle of standard transformer. This transformer usually needs to select the primary rated voltage in combination with the actual situation, and then select the secondary rated voltage. Generally, it needs to determine the rated current of each winding according to the load situation, and it is required to be greater than and equal to the load current, At the same time, the corresponding transformer shall be selected according to the voltage and current of the secondary and the rated capacity of the secondary. b. For non-standard transformer, the corresponding primary rated voltage, secondary winding voltage, current capacity and power frequency shall be selected for non-standard transformer

2.3 selection of low voltage circuit breaker

low voltage circuit breaker, also known as automatic air switch, is an electrical component that combines control and protection functions. Generally, the mortgage circuit breaker will not frequently connect and disconnect the main power switch of the circuit and the switch of local current. In case of short circuit, overload, undervoltage and other related faults, it will cut off the circuit by itself, so as to effectively protect the electrical equipment connected in series. In addition, it is generally not necessary to replace the parts after disconnecting the fault current. Therefore, low-voltage circuit breakers are more and more widely used in CNC machine tools. The selection principle of low-voltage circuit breaker is that the rated current and voltage of low-voltage circuit breaker shall be greater than or equal to the normal working voltage and current of relevant lines and equipment. The withstand limit and the making and breaking capacity of the mortgage circuit breaker shall be greater than or equal to the maximum short-circuit current. At the same time, the rated voltage of the undervoltage release shall be equal to the rated voltage of the line, while the rated current of the overcurrent release shall be greater than or equal to the limit load current of the line side and the overall process is not good, which is particularly easy to produce the vibration surface

2.4 selection of contactors

contactors are mainly used to control the connection or disconnection of circuits and load circuits. They are usually composed of electromagnetic mechanism arc extinguishing device, contact system and other relevant parts. Their true working principle is that after the coil is energized, the electromagnetic attraction generated by the iron core effectively pulls the armature, However, the holding iron drives the contact system to act, so that the normally closed contacts are disconnected and some normally open contacts are closed. When the relevant coil is de energized, the electromagnetic force also disappears, the armature is usually fully released under the reactive spring force, and the contact system will also be reset. The selection principle of contactors is mainly to select the use category of relevant contactors in combination with the work task of controlling current load required by contactors. Generally, there are two types of rated voltage of contactors, which are 500V and 300V respectively. However, they are required to be greater than or equal to the voltage of load circuit. It is mainly determined by the power of motor and relevant operation conditions to host the current top of contacts, The current type and voltage level of the contactor coil are generally the same as that of the control circuit, while the specific number and type of contacts should try to meet the needs of the circuit and the control circuit

in conclusion, CNC machine tool is a kind of mechatronic equipment that integrates Electromechanical, hydraulic and gas. The core of reliable operation of CNC machine tool lies in its electrical control system. Therefore, it is necessary to understand and master the functions and use principles of common control appliances of CNC machine tool, so as to repair and transform the fault of electrical control of CNC machine tool, There are also design and other aspects of effective help, so as to ensure the reliable and stable operation of CNC machine tools

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