The five-axis CNC machine tool is a machine with high technology and high precision for machining complex curved surfaces.
This machine tool system has a significant influence on a country’s aviation, aerospace, military, scientific research, precision equipment, high-precision medical equipment.
At present, the five-axis CNC machine tool system is the only means to solve the processing of impellers, blades, marine propellers, heavy-duty generator rotors, turbine rotors, large diesel engine crankshafts, etc.
Equipment manufacturing is the cornerstone of a country’s industry.
It provides an important means for the development of new technologies, new products and modern industrial production, and is an indispensable strategic industry.
Even the developed industrialized countries are highly valued.
With the rapid development of China’s national economy and the need for national defense construction, there is an urgent need for high-end CNC machine tools.
Machine tools are a symbol of the state’s manufacturing level.
On behalf of the highest level of machine tool manufacturing is the five-axis CNC machine tool system.
In a sense, it reflects the state of industrial development in a country.
For a long time, the western industrialized countries led by the United States have always used the five-axis CNC machine tool system as an important strategic material to implement an export licensing system.
In particular, during the Cold War, the embargo was imposed on the socialist camps such as China and the former Soviet Union.
A friend who loves military affairs may know the famous “Toshiba Incident”: At the end of the last century, Toshiba Corporation of Japan sold several five-axis CNC milling machines to the former Soviet Union. As a result, the propellers used to build submarines in the former Soviet Union were upgraded to higher level. The sonar of the US spy ship could not monitor the sound of the submarine. Therefore, Toshiba in the United States violated the strategic material embargo policy and was under punishment then.
There are cradle type, vertical type, horizontal type, NC table + NC indexing head, NC table + 90 ° B axis, NC table + 45 ° B axis, NC table + A axis, two axis NC spindle etc.
(1) Double oscillating head form (+A, +C)
(2) Drooping swing head type (+B, +C cutter)
(3) Double turntable form (NC workbench)
(4) Drooping work table type (+B, +CNC workbench)
(5) One swing and one turn form (+A, NC workbench)
The five-axis machining center has the characteristics of high efficiency and high precision, and the workpiece can be processed in one time with the pentahedron.
If equipped with a five-axis high-grade CNC system, it can also process high-precision space surfaces with high precision, and it can adapt to the processing of modern molds such as auto parts and aircraft structural parts.
There are two ways for the rotary shaft of the vertical five-axis machining center, one is the rotary axis of the table.
The table set on the bed can be rotated around the X axis, defined as the A axis.
The A-axis has a general working range of +30 degrees to -120 degrees.
There is also a turntable in the middle of the workbench.
Rotate around the Z axis at the position shown, defined as the C axis, and the C axis is 360 degrees.
Thus, through the combination of the A-axis and the C-axis, the workpieces fixed on the table can be machined by the vertical spindle except for the bottom surface.
The minimum dividing value of the A-axis and the C-axis is generally 0.001 degrees, so that the workpiece can be subdivided into arbitrary angles, and the inclined surface, the inclined hole can be processed.
The A-axis and the C-axis can be combined with the XYZ three linear axes to process complex spatial surfaces.
Of course, this requires high-end CNC systems, servo systems and software support.
The advantage of this arrangement is that the structure of the spindle is relatively simple, the rigidity of the spindle is very good, and the manufacturing cost is relatively low.
However, the general workbench cannot be designed too large and the load is small.
Especially when the A-axis rotation is greater than or equal to 90 degrees, the workpiece will bring a large load-bearing moment to the table when cutting.
The other is the rotation of the vertical spindle head.
The front end of the spindle is a turret, which can wrap 360 degrees around the Z axis and become the C axis.
There is also an A-axis on the turret with a rotation around the X-axis, typically up to ±90 degrees, to achieve the same function described above.
The advantage of this type of setting is that the spindle machining is very flexible and the workbench can be designed very large.
The huge fuselage and huge engine casing of the passenger aircraft can be processed on such machining centers.
This design also has a big advantage: when we use the spherical milling cutter to machine the surface and the tool center line is perpendicular to the working surface, the surface quality of the workpiece cut by the vertex will be very poor because the vertex line speed of the spherical milling cutter is zero.
The design of the spindle rotation makes the spindle rotate through an angle with respect to the workpiece, so that the spherical milling cutter avoids the cutting of the apex, ensuring a certain line speed and improving the surface processing quality.
This structure is very popular with the high-precision surface machining of the mold, which is difficult to achieve in the rotary machining center of the table.
In order to achieve high precision of the rotation, the high-end rotary shaft is also equipped with circular encoder feedback, and the indexing accuracy is within a few seconds.
Of course, the rotary structure of such a spindle is relatively complicated and the manufacturing cost is also high.
Foreign five-axis CNC machine tools have emerged to adapt to the processing of polyhedral and curved parts.
With the new development of machine tool compounding technology, on the basis of CNC lathes, a turning and milling center capable of milling is quickly produced.
The machining efficiency of the five-axis CNC machine tool is equivalent to two three-axis machine tools, and sometimes it can even completely eliminate the investment of some large-scale automated production lines, which greatly saves the space and the working time and cost of working between different manufacturing units.
The demand of the market has promoted the development of China’s five-axis CNC machine tools. At the CIMT99 exhibition, the domestic five-axis CNC machine tools first entered the stage of the machine tool market.
At present, the domestic five-axis CNC machine tools already have vertical, horizontal, gantry and floor-type machining centers in the variety, to adapt to the processing of miscellaneous parts of different sizes.
The development of five-axis milling machines and large boring and milling machines, as well as turning and milling centers, basically covers the needs of the domestic market.
The machining center which developed by Beijing Machine Tool Research Institute, the NJ25HMC40 horizontal machining center developed by Ningjiang Machinery Group Co., Ltd. and the TH61160 horizontal boring and milling machining center developed by Jiaoda Kunji Technology Co., Ltd. all have high precision. It is comparable to products from developed countries.
In the product market sales, the products of many machine tool companies have been recognized by the domestic market.
On the morning of July 31, 2013, the high-precision five-axis vertical machine tool manufactured by Dalian Kede was shipped to Germany for export.
Wang Weiming, deputy director of the Equipment Department of the Ministry of Industry and Information Technology, said: “This high-end CNC machine tool is sold to developed countries and is an important milestone in the Chinese machine tool manufacturing industry.”
It is generally believed that the five-axis CNC machine tool system is the only means to solve the processing of impellers, blades, marine propellers, heavy-duty generator rotors, turbine rotors, large diesel engine crankshafts, etc.
It is a machine tool with high technology and high precision for machining complex surfaces.
The machine tool system has a significant influence on a country’s aviation, aerospace, military, scientific research, precision instruments, high-precision medical equipment industries.
The use of a five-axis machine makes it easy to clamp the workpiece.
No special fixtures are needed during processing, which reduces the cost of the fixture, avoids multiple clamping and improves the precision of mold processing.
Machining molds with five-axis technology can reduce the number of fixtures used.
In addition, because the five-axis machine saves many special tools during machining, the tool cost is reduced.
The five-axis machine tool can increase the effective cutting edge length of the tool during machining, reduce the cutting force, improve the tool life and reduce the cost.
The use of five-axis machine tool can quickly complete the mold processing, fast delivery, better guarantee the processing quality of the mold, make mold processing easier, and make mold modification easier.
In the traditional mold processing, the vertical machining center is generally used to complete the milling of the workpiece.
With the continuous development of mold manufacturing technology, some weaknesses of the vertical machining center itself are becoming more and more obvious.
Modern mold processing is commonly processed using ball end mills.
Ball-end milling cutters bring significant benefits in mold processing.
However, if a vertical machining center is used, the line speed of the bottom surface is zero, so that the bottom surface has a poor finish.
If you use four or five-axis machining technology to process the mold, you can overcome the above shortcomings.
- The first is to use linear motor drive technology
After more than ten years of development, linear motor technology has been very mature.
The problem that the linear motor has just been developed to be susceptible to interference and large heat generation has been solved.
The positioning technology of the linear motor not only stops quickly during high-speed movement, but also some machine tool manufacturers use damping technology to solve it.
The advantages of linear motors are linear drive, no drive train, no wear, no backlash, so you can achieve the best positioning accuracy.
Linear motors have high dynamics and accelerations can exceed 2g.
Linear motor drive is also highly reliable and maintenance-free.
- Followed by dual drive technology
For the wider workbench or gantry type, if the intermediate drive is used, the driving force is not guaranteed to be centered, which tends to cause tilting, resulting in poor dynamic performance.
With dual drives, dual scales and a drive module, dynamic performance is perfect.
A drive command, the dual drive works at the same time, the grating ruler to detect whether the two points are balanced.
If it is unbalanced, it is balanced by different instructions.
Of course, the development of five-axis machine technology is far more than that, and many technologies will be reflected in DMG’s machine tools.
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