2020 – Page 90 – CNC Machining & Turning, Milling, Metal parts

What are the general principles of precision parts processing?

1. Benchmark first

That is to say, the datum plane should be processed first. In the process of machining, the surface as the positioning datum should be processed first, so as to provide the precision datum for the subsequent processing as soon as possible.

2. Division of processing stages

The appearance with high machining quality request can be divided into three stages: rough machining, semi finish machining and finish machining. The main purpose is to ensure the processing quality; to facilitate the scientific application of equipment; to facilitate the arrangement of heat treatment process; and to facilitate the detection of blank defects.

3. Face before hole

For the box, bracket, connecting rod and other parts, the plane shall be machined before the hole is machined. In this way, the hole can be machined by plane positioning, ensuring the position accuracy of plane and hole, and bringing convenience to the machining of hole on plane.

4. Finishing

Finishing of main surfaces, such as grinding, honing, finishing, rolling, etc., shall be placed at the end of the process route. The general principle of drawing up the processing route of precision parts and the formulation of the processing procedure of precision parts can be roughly divided into two parts. First of all, it is to draw up the process route of parts processing, and then determine the process size of each process, used equipment and process equipment, cutting specifications, working hours quota, etc.

How to process precision machine parts?

(1) Rough machining stage. Most of the machining allowance of each machining surface shall be cut off and the precision datum shall be machined. The first consideration is to improve the productivity as much as possible.

(2) Semi finishing stage. Remove the possible defects after rough machining, prepare for the finish machining of the surface, require to reach a certain machining accuracy, ensure the appropriate finishing allowance, and complete the processing of the secondary surface together.

(3) Finishing stage. In this stage, large cutting speed, small feed rate and cutting depth are selected to cut off the finishing allowance left by the previous process, so as to make the part surface meet the technical requirements of the drawing.

(4) Finishing stage. It is mainly used to reduce the surface roughness value or strengthen the surface processing. It is mainly used for the surface processing with high surface roughness requirements (RA ≤ 0.32 μ m).

(5) Super fine machining stage. The machining accuracy is 0.1-0.01 μ m, and the surface roughness Ra ≤ 0.001 μ M. The primary processing methods are: fine cutting, fine mirror grinding, fine grinding and polishing.

What are the advantages of precision hardware processing?

1. CNC machining precision of fine metal shaft is high, with stable processing quality;

2. Multi coordinate linkage can be carried out, and parts with disordered shapes can be processed;

3. When the fine hardware CNC machining parts are changed, generally only the NC program needs to be changed, which can save the production preparation time;

4. The machine tool itself has high precision and rigidity. It can choose favorable processing amount and high production rate (generally 3-5 times that of general machine tools);

5. The machine tool has a high degree of automation, which can reduce the labor intensity;

The short cutting tool is the main feature of CNC fine machining. The short cutting tool will obviously reduce the deviation of cutting tool, and then achieve outstanding surface quality, avoid rework, reduce the use of electrode, and shorten the EDM processing time. When considering the five axis machining, it is necessary to consider the principle of using the five axis machining die: finish the whole workpiece machining with the shortest cutting things as possible, also including cutting programming, clamping and machining time, but get more perfect surface quality.

The effect of precision machining technology

Generally in normal temperature processing, and do not cause changes in the chemical or physical phase of the workpiece, called cold processing. Generally, the processing above or below normal temperature will cause chemical or phase change of the workpiece, which is called hot processing. Cold working can be divided into cutting and pressure machining according to different machining methods. Hot working includes heat treatment, casting, casting and welding.

The technological functions of precision machining are as follows:

1. The accuracy of several shapes and orientations of parts can reach micron or angular second;

2. The tolerance of the boundary or feature dimension of the part is below micrometer;

3. The surface micro unevenness (average height difference of surface unevenness) of parts is less than 0.1 μ m;

4. Mutual fittings can meet the requirements of combining force;

5. Some of the parts can also meet the requirements of accurate mechanical or other physical characteristics, such as the torsional rigidity of the torsion bar of the float gyroscope, the rigidity coefficient of the flexible element, etc.

Key technologies of CNC machining and cutting development

In order to reduce the auxiliary time and increase the efficiency, it is required that the starting and stopping time of the main shaft of CNC machine tool CNC Mechanical and electrical engineering be as short as possible, so high starting and stopping plus (minus) speed is required. At present, the start-up and stop acceleration of the main shaft of CNC Mechanical and electrical engineering of overseas machine tools can reach above LG, and the time of full speed start-up and stop is within 1 s.

The CNC mechanical and electrical engineering spindles made by these companies have the following characteristics compared with those made in China: high power and high speed; high-speed and high rigidity bearings are selected; high-speed and high rigidity bearings are selected for overseas high-speed and compact spindles, with the emphasis on ceramic bearings and liquid dynamic and static pressure bearings; air smooth bearings and magnetic bearings are selected for unique scenes; The process level of careful processing and equipment is high; the level of supporting control system is high. These control systems include rotor automatic average system, bearing oil and gas smooth and careful control system, stator and rotor cooling temperature careful control system and spindle deformation temperature compensation careful control system, etc. On this basis, these foreign manufacturers, such as the United States, Japan, Germany, Italy, Switzerland and other industrialized countries, have made a variety of commercialized high-speed machine tools.

Development trend of spindle technology in CNC Mechanical and electrical engineering

Continue to develop towards the goal of high speed and high rigidity

Due to the demand of high-speed CNC machining and essential use, with the development of spindle bearing and its smooth technology, careful machining technology, careful moving average technology, high-speed cutter and its interface technology and other related technologies, the high-speed spindle of CNC Mechanical and electrical engineering for CNC machine tools has become the current development trend, such as CNC Mechanical and electrical engineering for drilling and milling, ibag in Switzerland The speed of hf42 reached 140000 R / min, and that of d1733, a PCB drilling machine of westwind company in the UK, reached 250000 R / min. The main shaft of CNC Mechanical and electrical engineering for machining center was 42000 R / min for Fischer in Switzerland and 75000 R / min for camfior in Italy. In terms of the system rigidity of CNC Mechanical and electrical engineering spindles, the system rigidity of CNC Mechanical and electrical engineering spindles is increasing due to the development of bearings and their smooth technology, which meets the needs of the development of CNC machine tools in high-speed, high-efficiency and precision machining.

Towards the goal of high speed, high power, low speed and high torque

According to the demand of essential application, numerous CNC machine tools can meet the requirements of Heavy CNC machining and high-speed CNC machining at the same time. Therefore, the CNC Mechanical and electrical engineering spindle of machine tool should have the performance of low speed, high torque and high power. The main shaft of CNC Mechanical and electrical engineering for machining centers made by camfior, step Tec of Switzerland and GMN of Germany is satisfactory. It is not difficult for the main shaft of CNC Mechanical and electrical engineering of Cytec of Germany to transmit torque above 200 N · m in low speed section. The main shaft of CNC Mechanical and electrical engineering of CNC milling machine and lathe of Cytec of Germany has reached 630 n · m in large torque, and in high speed section, it is usually at 10-50 kW; The great transmission power of cyteccnc CNC CNC Mechanical and electrical engineering spindle is 50 kW; the great power of Swiss step teccnc mechanical and electrical engineering spindle is 65 kW (S1), which is used for aircraft manufacturing and mold processing; and the report of CNC Mechanical and electrical engineering spindle power reaching 80 kW is more.

Further development to the goal of high precision, high reliability and long working life

Users put forward higher and higher requirements for the accuracy and reliability of CNC machine tools. As one of the core performance components of CNC machine tools, CNC Mechanical and electrical engineering spindle requires higher and higher accuracy and reliability. For example, the radial runout of the main shaft is within 0.001 m m, and the axial positioning accuracy is below 0.5 μ M. At the same time, the service life of CNC Mechanical and electrical engineering spindle has been lengthened and its application reliability has become higher and higher due to the selection of special and careful spindle bearing, advanced smooth mode and unique preload application mode. Step TEC’s CNC Mechanical and electrical engineering spindle is also equipped with acceleration sensor to reduce the vibration acceleration level of bearing. In order to monitor and limit the vibration on the bearing, a vibration monitoring module is installed to prolong the working life of CNC Mechanical and electrical engineering spindle.

The performance and mode diversification of the spindle’s built-in electromechanics in CNC

In order to meet the demand of essential use, the performance of spindle motor in CNC Mechanical and electrical engineering has been improved. For example, the ratio of constant torque and high speed to constant power and high speed (i.e. constant power speed regulation boundary) delivered by Fischer spindle motor in Switzerland has reached 1:14. In the rest, permanent magnet synchronous motor CNC Mechanical and electrical engineering spindles appear. Compared with asynchronous motor CNC Mechanical and electrical engineering spindles of the same power, the appearance size of synchronous motor CNC Mechanical and electrical engineering spindles is small, which is conducive to increasing power density and completing small size and large power rate.

Start and stop the response quickly

Technological process of precision parts processing mould

The process of precision parts machining is the process of mould manufacturing, which transforms the design of mould parts into the products of mould parts. It includes the work of design, parts manufacturing, standard parts purchasing, mould equipping and mould test acceptance. The following is the process of precision mould parts machining explained by a small editor.

The key mission of discussing the manufacturing process of precision parts mould is to discuss the possibility of mould manufacturing and how to deal with the problem of mould manufacturing. A mould is composed of several parts. The fundamental prospect is to seek the processing of precision mould parts with low cost, short cycle and high quality. Cost, cycle and quality are the key economic and technical indicators of mold manufacturing. We should not study the three indicators alone, but should study them comprehensively, so that the three links of design, manufacturing and application are in harmony with each other.

In the design, we should not only study the application performance, but also fully study the feasibility of manufacturing; in the manufacturing, we should meet the design requirements and guide users to use. Design and manufacturing also need to understand to make the design convenient for manufacturing under the condition of meeting the application performance; the detailed process of mold manufacturing is as follows:

The above is all about the technological process of precision parts processing mold. If there is a need for processing design, please call us.

How to choose high efficiency CNC production line

At present, the varieties of CNC processing lines include rigid automatic line and flexible CNC processing line. Which kind of CNC processing line is located in the CNC processing field should be confirmed according to the change of products and output. If it is a large number of production, and is mature production line, then should choose rigid line, because the working efficiency is high. However, if it is a small and medium-sized batch, and the product has certain transformation, then flexible line should be selected, because the process of this production line is a set of control, and has strong suitability.

Other factors, such as the change degree of CNC production line, product life cycle and product change, are also what we need to study when choosing production line. In this respect, the flexible production line is better than the rigid production line, because it is more sensitive, more suitable, and can reduce the investment crisis.

At present, there is a new method of CNC machining production line, which is the combination of automatic line and flexible CNC machining center, resulting in the production line, which is mainly the automatic production line, to ensure the processing accuracy and the stability of the production line. For other processes, CNC machining is used. This production line also has certain advantages, so there will be, but also according to the nature of the situation to determine whether it is appropriate, can not be confused to use.

Precision parts processing can meet your requirements

We will use many parts in our life, that is to say, we will use many parts when we use many machines. But our parts can’t be precise occasionally. At this time, we might as well go to buy precision parts. Why? Because a original precision part might as well be worth a lot of our ordinary parts. Without this good precision part, many of our machines would be very difficult to use.

But we often have such things, that is, we will occasionally find our own precision parts are still not good. Take the car for example, if our car breaks down, we go to buy parts, buy precision parts and find that it still cannot meet the requirements of our car. Then you need such equipment for precision parts processing, that is to say It is such a simple thing to process the precision parts you still buy and then meet the requirements of your machinery.

Precision parts processing, to meet any requirements of your machinery.

The influence of ultra precision CNC machining technology

Ultra precision CNC machining technology has significant economic benefits, social benefits and market demand prospects: ultra precision machine tool is the carrier of high-level CNC machining technology, with high development cost, long cycle and high value of each machine. If it can replace the import of an ultra precision machine tool, it will save millions of dollars; if the value of its annual machining creation is calculated, the economic benefits are significant.

Ultra precision CNC machine tool is an indispensable equipment for the development of national defense cutting-edge and high-tech products. It has always been regarded as a strategic material by some powerful family property countries and is banned for export. If China does not develop its own machine tool, it is difficult to buy it if necessary, so the social benefits are great.

With the development of science and technology and people’s economy, the demand for ultra precision machining technology is becoming more and more superior, and the market is expanding. Its application is not limited to the cutting-edge of national defense and aerospace, but has expanded to various boundaries. Its application scale and demand are larger, so the market demand prospect is optimistic. The detailed analysis is as follows.

The use of CNC processing is becoming mediocre and the market demand is expanding. The boundary of ultra precision CNC processing technology is becoming more and more mediocre, which is used in the boundary of high-tech technology, military property and civil property. Therefore, it is an indispensable skill for the development of high and new technology and products.

Machining quality of precision parts is expressed by machining precision

1、 Interchangeability of parts

According to the precision parts manufacturer, after long-term production and operation, some parts will inevitably wear and deform and be scrapped, replacing with new parts. These parts are called accessories or spare parts. Accessories or spare parts without repair or selection, installed on the machine can run, known as exchange.

In order to achieve interchangeability, when manufacturing parts, we should make the size and geometry of the parts as a whole. The so-called “all in all” does not require that the score is not poor at all (it is neither economical nor possible to do so). As long as the size and geometry of the parts are controlled within a promised boundary, so that the parts and other parts have the same fusion function after fusion. The promised deviation line is the official of form and position.

2、 The machining quality of precision parts is expressed by machining accuracy:

1. Geometric form accuracy

The accuracy of geometric form refers to the accurate level of geometric form such as the surface or axis of the part, such as whether the line is straight, whether the surface is flat, and whether the normal section on the cylinder is round, etc. The allowable change boundary is expressed by “shape and position yamen servant”. The smaller the number of shape and position yamen servant is, the higher the form accuracy is.

2. Dimensional accuracy

According to the analysis of precision parts processing factory, dimensional accuracy refers to the accurate level of the dimension after the parts are processed, which is represented by “dimension yamen runner”. When the dimensions of the parts are the same, the higher the accuracy, the smaller the Yamen number.

3. Position accuracy

According to the precision parts manufacturer, the position accuracy refers to the accurate level of the mutual position between the surfaces of the parts, such as whether the two planes are parallel, vertical, and whether the two axes are coaxial.

The Yamen servants in the above forms and positions are referred to as “yamen servants in shape and position”.