Machining Methods

Technical characteristics of horizontal and floor milling and boring machines

Technical characteristics of horizontal and floor milling and boring machines

In recent years, the technology development of horizontal boring and milling machines and floor milling and boring machines at home and abroad has been developing very quickly. It is characterized by the continuous updating of product structure, the endless application of new technologies, the composite of process performance, the continuous improvement of speed and efficiency, and the emphasis on refined manufacturing.

The development of horizontal boring and milling machines has attracted much attention due to its injection acceleration concept. The transmission elements such as electric spindles, linear motors, and linear guides, which are technically supported for high-speed operation, have been widely used, pushing the running speed of machine tools to a new level. The innovative design of the horizontal spindle boring and milling machining center with replaceable spindle solves the shortcomings of the advantages and disadvantages of the telescopic structure of the electric spindle and boring bar. It has the effect of composite processing and one machine, and it is also a major issue of the horizontal boring and milling machine. Technological innovation.

The development of floor-type milling and boring machines leads the trend of modern processing with its new design concept. The structure type with no boring shaft ram type and the exchange of various milling heads with the concept of high-speed machining is very elegant, and it greatly replaces traditional milling processing. the trend of. Various milling head attachments represented by two-coordinate swing-angle milling heads have become the main means of achieving high-speed and efficient composite machining. Its wider process performance, greater power and stronger rigidity are a major breakthrough in the development of floor milling and boring machines.

Structural features

Horizontal boring and milling machine

The main key component of the horizontal boring and milling machine is the spindle box, which is installed on the side of the column. There are also a few manufacturers that use the thermal symmetry structure of the double column to place the spindle box in the middle of the column. The biggest feature of this structure is the rigidity, balance, and good heat dissipation performance. , Which provides a reliable guarantee for the high-speed operation of the spindle box. However, the double-column structure is not easy to maintain, which is the reason why not many manufacturers use it today. The movement of the spindle box is mostly driven by the motor-driven ball screw. It is the core drive device of the spindle drive. It is mostly supported by static pressure bearings and driven by the servo motor-driven ball screw. As the spindle speed is getting higher and higher, the spindle temperature is rising fast. Now, many manufacturers will use oil mist cooling instead of oil cooling to control the spindle temperature more effectively, so that its accuracy is effectively guaranteed.
There are two main types of spindle system, one is the traditional boring bar telescopic structure, which has the characteristics of boring deep holes and high-power cutting; the other is the modern high-speed electric spindle structure, which has high speed, fast running speed and high efficiency , The advantages of high precision.
The application of high-speed electric spindles on horizontal boring and milling machines is increasing. In addition to the significant increase in spindle speed and accuracy, it also simplifies the internal structure of the spindle box and shortens the manufacturing cycle. Especially for high-speed cutting, the maximum speed of the electric spindle can be Larger than 10000r/min. The disadvantage is that the power is limited, and its manufacturing cost is high, especially deep hole processing. The boring bar telescopic structure has limited speed, although the accuracy is not as good as the electric spindle structure, but it can perform deep hole processing, and the power is large, it can be processed at full load, and the efficiency is high, which is unmatched by the electric spindle. Therefore, the two structures coexist and the process performance is different, but it provides users with more choices.
Now, a replaceable spindle system has been developed, which has the effect of one machine and two uses. The user chooses to use it according to different processing objects, that is, the electric spindle and the boring bar can be used interchangeably. This structure takes into account the shortcomings of the two structures, and also greatly reduces costs. It is a major innovation of today’s horizontal boring and milling machines. The advantages of the electric spindle are high-speed cutting and fast feed, which greatly improves the accuracy and efficiency of the machine tool.
The running speed of horizontal boring and milling machine is getting higher and higher, the fast moving speed reaches 25~30m/min, and the maximum speed of boring bar is 6000r/min. The horizontal machining center has higher speed, rapid movement up to 50m/min, acceleration of 5m/s2, position accuracy of 0.008~0.01mm, and repeated positioning accuracy of 0.004~0.005mm.

Floor milling and boring machine milling cutter

Because the floor-type milling and boring machine is mainly used for processing large parts, the milling process has a wide range, especially high power and powerful cutting is a major processing advantage of the floor-type milling and boring machine, which is also the traditional process concept of the floor-type milling and boring machine. The technological development of contemporary floor milling and boring machines is changing the traditional process concepts and processing methods. The high-speed machining process concept is replacing the traditional heavy cutting concept, bringing high-speed, high-precision and high-efficiency changes to the processing technology, which also promotes The structural changes of the floor-type milling and boring machine and the improvement of technical level have been introduced.

Today, the biggest feature of the development of floor-type milling and boring machines is the development of high-speed milling. They are all of the ram type (no boring shaft) structure, and are equipped with various milling head accessories with different technological properties. The advantage of this structure is that the ram has a large cross-section, good rigidity, long stroke, and fast moving speed. It is easy to install various functional accessories, mainly high-speed boring, milling head, two-coordinate double-swing angle milling head, etc. The performance and processing range reach the extreme, greatly improving the processing speed and efficiency.
Traditional milling is processed by boring bars, while modern milling is mostly completed by various functional accessories through rams. There has been a trend to replace traditional machining. Its advantages are not only the speed and efficiency of milling, but also the main The processing of polyhedrons and curved surfaces cannot be accomplished by traditional processing methods. Therefore, nowadays, many manufacturers are competing to develop and produce ram-type (without boring shaft) high-speed machining centers, because of its economic efficiency, obvious technical advantages, and can greatly improve the process level and process scope of the machine tool. At the same time, it also improves the processing accuracy and processing efficiency. Of course, various types of high-precision milling head accessories are required for technical support, and their requirements are also very high.

High-speed milling has brought structural changes to the floor-type milling and boring machine. The structure with the spindle box centered is more common. Its high rigidity is suitable for high-speed operation. The ram drive structure uses linear guides and linear motors. This structure is necessary for high-speed cutting. Foreign manufacturers have adopted it on floor-type milling and boring machines. Domestic similar products are still rare. Linear is only used on small and medium-sized machine tools. guide. High-speed machining also puts forward higher requirements on the environment and safety, which has produced the concept of pleasant production. All manufacturers attach great importance to the safety protection and operability of people under high-speed operation of the machine tool. The fully enclosed structure is implemented, which is safe and beautiful.

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