2017年11月1日星期三

Equipment management of CNC universal milling machine

Equipment management of CNC universal milling machine is a systematic project, and should be based on the company’s production development and business objectives, through a series of technical, economic, organizational measures and scientific methods to carry out. In the specific use of equipment management, depending on the enterprise to buy and use CNC universal milling machine, select the following stages.
①In the early use of CNC universal milling machine, there is no mature management methods and the use of equipment experience, programming, operation and maintenance personnel are more unfamiliar. In this case, the CNC universal milling machine is generally placed under the production workshop management, focusing on training several technical staff to learn manual programming, automatic programming and maintenance techniques, and then teach the operator, and for a long time to allow technicians and operate workers as top class operation. Select the typical key parts of the enterprise, the preparation process, select the tool, determine the fixture and preparation procedures and other technical preparations.
②In the grasp of a certain application of technology and a certain number of  milling machines, these devices can be used professional management, centralized use of the method. Process technology preparation by the process sector is responsible for the production management by the factory unified balance and scheduling, CNC equipment concentrated in the CNC workshop.
③CNC machine tools and the number of more types of auxiliary facilities are relatively complete, relatively mature application technology, programming, operation and maintenance of the technical team is relatively strong, can be equipped with CNC machine tools in the appropriate general machine, the CNC workshop expanded into closed independent workshop, with the ability to independently produce a complete product. If necessary, equipment and tools can be achieved computer management, universal milling machine to start a higher rate of technical and economic benefits are better.
Whichever stage is used, equipment management must establish rules and regulations. Such as the establishment of fixed, fixed machine, fixed post system, job training, prohibition of undocumented operation. According to the characteristics of the equipment, the development of the operation and maintenance of safety procedures. In the equipment maintenance, to strictly enforce the record, that is, for each maintenance are doing the relevant records. The fault repair to do a good job on the fault records and instructions, and equipment maintenance and repair for all kinds of commonly used spare parts. Do the equipment technical information on the lend, custody, registration work.

2017年10月29日星期日

Milling machine CNC system hardware

From the hardware point of view, milling machine CNC system is divided into single microprocessor numerical control system and multi microprocessor numerical control system.
1. Single microprocessor numerical control system
In a single microprocessor numerical control system, the whole system has only one CPU, it uses centralized control, time-sharing way to control. Single microprocessor numerical control system of the main features of the performance: CPU time-sharing control. CPU through the address, data and control of the three major bus connected to the control unit and the exchange of information.
2. Multi-microprocessor numerical control system
Multi-microcomputer numerical control system will control the task is divided into various modules, each module by a separate microprocessor to control. The system through the coordination of the various modules to complete the control of the milling machine. Compared with the single microprocessor numerical control system, the operation speed of the multi-microprocessor numerical control system has been greatly improved.
Multi-microprocessor functional modules include:
1) management module. Used to manage and organize the entire milling machine CNC system work.
2) interpolation module. Mainly to complete the pre-processing before interpolation.
3) position control module. Used to compare the position setpoint with the actual value of the position, and adjust the output speed command to drive the milling machine feed motor.
4) memory module. The memory module is the main memory of the program and data, or the shared memory for data transfer between the functional modules.
5) PLC function module. It is part of the program in the switch function and the milling machine to the logic of the signal processing, to achieve the machine electrical equipment switching control.
6) operation panel and display module. This module includes part program, parameters and data, various operation commands input/output and display the various interface circuits required.
In the CNC system of multi microprocessor, the communication and communication between modules are mainly composed of shared bus and shared memory, two kinds of structure. In the shared bus architecture, each function module is plugged into a chassis with a bus socket, and the modules are effectively connected together by the milling machine system bus. In the shared memory architecture, each module exchanges information with the common memory, and the public memory is directly attached to the system bus, and each module can access the information.

2017年10月27日星期五

Milling machine CNC system

As the computer system of CNC milling machine, CNC system is very important to control the whole machining process of machine tools. In short, the role of numerical control system is: the input of the processing program after a series of data processing, the output of the control signal to the milling machine to complete the implementation of the processing procedures specified by the action, including the spindle movement, feed movement and auxiliary Features. In addition, the CNC system can also be connected with the computer or network, the implementation of data transmission and communication.
The CNC machining program contains information such as spindle S command, track command G00, G01, G02, G03, coordinate value command X, Y, Z, speed command F, auxiliary function command M. CNC system needs to carry out data processing of these information, and output the control signal.
After the machining program is input to the CNC system, the milling machine CNC system must decode the processing program and generate the data format which the numerical control system can recognize. The decoding result is stored in the specified register, such as the M code register, the G code register, the X, Y, Z registers, etc., for later data processing.
One way to decode is to translate the entire program once before the formal processing and to parse the program during the decoding process. Another way is to decode during processing, that is, the milling machine CNC system in the implementation of the current process block processing, the use of idle time on the subsequent program to decode and follow-up data processing, this approach is also known as preread processing. The more readable blocks, the more data processing functions of CNC systems.
The above is a brief introduction to the milling machine CNC system. In the next article, we will be from several aspects to carry out a more detailed description.

2017年10月26日星期四

CNC milling machine rotary transformer

The rotary transformer is a precision sensor that uses the electromagnetic induction principle to measure the angle, and is widely used in CNC milling machine. Rotary transformers are made of fixed, rotor core and windings, durable, unlike the encoder in the photoelectric encoder vulnerable to shock or vibration damage, suitable for use in harsh environments. Milling machine servo motor in addition to optional optoelectronic encoder, but also optional rotary transformer, as shown.
The milling machine revolving transformer is actually a special two-phase motor. There are two orthogonal decomposition of winding stator windings, and the excitation voltage, when the rotor rotates, and the relative position of the rotor windings changes, the decomposition of the rotor winding of the induction voltage into a functional relationship with the rotor angle. 
The induced voltage varies with the rotation angle of the rotor, and the induced voltage can be detected to detect the rotor rotation angle. In order to lead the rotor coil on the induced voltage, the actual use of the rotary transformer consists of two parts: a part of the decomposition device, composed of stator and rotor, the other part of the transformer. The primary winding of the transformer and the rotor winding of the resolver are fixed on the rotating shaft and rotate together with the rotor. The rotor winding lead wire in the resolver is connected to the primary winding of the transformer. The secondary winding of the transformer and the stator in the resolver are fixed to the housing, respectively. The stator winding of the resolver is applied with an excitation voltage, and the induced voltage of the rotor winding when the rotor rotates is fed by the primary winding of the transformer by the secondary winding of the transformer.
Above is the basic working principle of CNC milling machine rotary transformers, thank you for your attention.

2017年10月25日星期三

CNC milling machine grating (Part 2)

In the last article we understand the basic composition, classification and function of the CNC milling machine grating, and today we look at the measurement principle of the grating.
In the transmission type incremental grating, when the grating with the light source, lens and a photosensitive element together with respect to the scale and move around the grating, grating and grating ruler to indicate the fringe produced optical phenomena, as shown in the grating generated on the move and the bright and dark stripes, the stripes called moire fringe.
Every move of a milling machine indicator grating pitch, which produce a moire fringe. The photosensitive element receives the change of the light and the dark of the moire fringe, namely, an electrical signal is generated, and the detection circuit processes the electrical signal generated by the photosensor and outputs a pulse signal. Because the width of the moire fringe is much larger than the pitch, the moire fringe has the effect of enlarging the pitch. Counting the output pulse, is to accumulate the pitch, the cumulative result is measured linear displacement. If the grating pitch is 20pm and the count pulse is 1000, the measured distance is 20μm * 1000 = 20000μm = 20mm.
In addition, the direction of the moire fringe movement is related to the direction of movement of the indicating grating. When the indicating grating is moved to the right, the moire fringes move down; and vice versa. Through a group of photosensitive elements on the moire fringes to detect the direction of movement, the output of two phase difference of 90° electrical signals to distinguish.
The above is the introduction on the CNC milling machine grating measurement principle, thank you for your attention.

2017年10月20日星期五

CNC milling machine grating (Part 1)

Grating is a high-precision position sensor, widely used in CNC milling machine, which mainly involves long grating and round grating two types. Long grating for the milling machine table and other moving parts of the linear displacement measurement, also known as linear grating. Round gratings are commonly used for angular displacement measurements such as rotary tables. The picture shows the grating installation diagram.
The grating body is fixed on the milling machine bed, the scanning head is fixed on the work table, the scanning head moves together with the work table, and the straight line displacement amount of the work table is converted into electric signal by cable output.
The picture shows the appearance and the internal structure of the grating. Ruler grating (also known as the main ruler) fixed in the body fixed. The ruler grating is made of optical glass or stainless steel strip. The ruler grating is engraved with equidistant stripe, which is called the pitch ω. 
In addition, the ruler grating is also engraved with a set of zero mark fringes, and according to the law of equidistant arrangement, its purpose is to return to the reference point in the process, to the nearest zero mark, save back to the reference point of time. The indicator grating (also known as the secondary ruler) corresponding to the ruler grating is also engraved with equally spaced stripes. Indicator grating is fixed in the scanning head and moved together with the scanning head. According to the projection of the light, the grating has two kinds of transmission grating and reflection grating.
The above is on the CNC milling machine grating of the basic composition, classification and the role of a brief introduction, you are welcome to continue to pay attention.

2017年10月19日星期四

Milling Machine Absolute Photoelectric Encoder

Milling machine absolute photoelectric encoder structure and incremental encoder is similar to the code, LED, photosensitive components and signal detection circuit and so on. The detection signal is binary coded, and each code corresponds to an angular position. The picture shows the absolute measurement and binary coding.
The milling machine has a code track (also known as track). As shown in the code on the code from the inside to the outside there are 8 yards, the code on the road by the binary law engraved with light or opaque stripes. The side of the disc is the light source and the other side is a group of photosensitive elements. When "0" to a certain angle, and the corresponding channel of the photosensitive element by the light output is "1" level, from the light output is "0" level, which constitutes a set of binary code. The number of bits in the binary code is the number of code channels, and each set of binary codes corresponds to a single angle, as shown.
Binary code has two types of natural binary code and Gray code. Natural binary code, the measured angle changes every time, binary coding may occur in a number of "0" and "1" changes, prone to error code, low reliability. Gray code, the measured angle changes every time, only one binary code "0" and "1" changes, Gray code is conducive to reducing the wrong code, improve reliability.
Because the binary code is distributed within 360°, when the code from 0°to 360°, the code back to the initial value, can not tell the number of turns of the code wheel, so when the angular displacement measurement, to using multi-turn absolute encoder.
The position data of the absolute encoder is stored in the memory, held by an external lithium battery, and the data is not lost after power failure. So the configuration of the absolute encoder CNC milling machine once the reference point after the completion of the set, after each boot power after the need to return to the reference point of the operation.
The above is a simple introduction to the milling machine absolute photoelectric encoder, hoping to help you.