In recent years, the technology of horizontal boring and milling machine and floor milling and boring machine has developed very fast. It is characterized by the continuous updating of product structure, the continuous application of new technologies, the compounding of process performance, the continuous improvement of speed and efficiency, and the emphasis on fine manufacturing.
The development of horizontal boring and milling machines has attracted much attention due to its concept of injection acceleration. Transmission elements such as electric spindles, linear motors, and linear guides, which are technical support for high-speed operation, have been widely used, pushing the machine’s operating speed to new heights. The innovative design of the spindle-replaceable horizontal boring and milling machining center solves the disadvantages of the advantages and disadvantages of the electric spindle and the boring bar mobile telescopic structure. It has the effects of composite machining and one machine dual use, and is also a major feature of horizontal boring and milling machines. Technical innovation.
The development of the floor-type milling and boring machine leads the trend of modern machining with its new design concept. The high-speed machining concept of the boring-shaft-free ram type and the use of a variety of milling head interchangeable structures are very elegant, and they are a great alternative to traditional milling. the trend of. Various milling head accessories represented by two-coordinate pendulum milling heads have become the main means to achieve high-speed and efficient composite machining. Its wider process performance, greater power, and greater 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 a horizontal boring and milling machine is the headstock, which is installed on the side of the column. There are also a few manufacturers who use a double-column thermosymmetric structure and place the headstock in the middle of the column. The biggest feature of this structure is rigidity, balance, and good heat dissipation. Provides a reliable guarantee for high-speed operation of the headstock. However, the double-pillar structure is not easy to maintain, which is why there are not many manufacturers using it today. The movement of the headstock is mostly driven by a motor-driven ball screw. It is the core drive of the spindle drive. It is mostly supported by a hydrostatic bearing and is driven by a servo motor driving the ball screw. Because the spindle speed is getting higher and higher, and the spindle is heating up faster, now many manufacturers will use oil mist cooling instead of oil cooling, to control the spindle temperature more effectively, and ensure its accuracy.
There are two main types of spindle system, one is the traditional boring bar telescopic structure, which has the characteristics of deep boring and high-power cutting; the other is the modern high-speed electric spindle structure, which has high speed, high speed and high efficiency. The advantages of high precision.
High-speed electric spindles are increasingly used in horizontal boring and milling machines. In addition to the significant increase in spindle speed and accuracy, the internal structure of the spindle box is simplified, and the manufacturing cycle is shortened. In particular, high-speed cutting can be performed. More than 10000r / min. The disadvantage is that the power is limited and its manufacturing cost is high, especially for deep hole machining. The boring bar telescopic structure has limited speed. Although the accuracy is not as good as that of the electric spindle structure, it can perform deep hole machining, and has high power, can be processed at full load, and high efficiency, 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 function of one machine and dual purpose. Users can choose to use it according to different machining objects, that is, the electric spindle and boring bar can be replaced and used. This structure takes into account the shortcomings of the two structures, and also greatly reduces costs. It is a great innovation of today’s horizontal boring and milling machine. The advantages of electric spindles 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 a higher speed, a rapid movement of up to 50m / min, an acceleration of 5m / s2, a position accuracy of 0.008 to 0.01mm, and a repeat positioning accuracy of 0.004 to 0.005mm.
Floor milling and boring machine milling cutter
Since floor-type milling and boring machines are mainly for machining large parts, the milling process has a wide range. Especially high-power and powerful cutting is a major machining advantage of floor-type milling and boring machines. This is also the traditional process concept of floor-type milling and boring machines. The technological development of contemporary floor milling and boring machines is changing the traditional process concepts and machining methods. The high-speed machining technology concept is replacing the traditional heavy-cutting concept, bringing high-speed, high-precision, and high-efficiency changes to the machining methods, thereby also promoting The structural changes of floor-type milling and boring machines and the improvement of their technical level are described.
Today, the biggest feature of the development of floor milling and boring machines is the development of high-speed milling. They are all ram-type (without boring shaft) structure and are equipped with a variety of milling head attachments with different technological performances. The advantage of this structure is that the cross section of the ram is large, the rigidity is good, the stroke is long, and the moving speed is fast. It is easy to install various functional accessories, mainly high-speed boring, milling heads, two-coordinate double-swing angle milling heads, etc. The performance and machining range reach the extreme, which greatly improves the machining speed and efficiency.
Traditional milling is processed by boring bar, while modern milling is performed 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 mainly The machining of polyhedrons and curved surfaces cannot be completed by traditional machining methods. Therefore, many manufacturers are now competing to develop and produce ram-type (no boring shaft) high-speed machining centers because of its economy, obvious technical advantages, and can greatly improve the process level and scope of machine tools. At the same time, machining accuracy and machining efficiency are improved. 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 of the center of the headstock is more common, and its rigidity is high, which is suitable for high-speed operation. The ram drive structure uses linear guides and linear motor drives. This structure is necessary for high-speed cutting. Foreign manufacturers have used it on floor milling and boring machines. Similar domestic products are rare, and only linear machines are used on small and medium-sized machines. guide. High-speed machining also puts forward higher requirements on environment and safety, which has also brought about the concept of pleasant production. All manufacturers attach great importance to the safety protection and operability of people under the high-speed operation of machine tools. Fully enclosed structure is safe and beautiful.
Process Characteristics
Traditional horizontal boring and milling machines are mainly suitable for machining various mechanical parts, especially mechanical transmission boxes and various curved body parts. Due to the improvement of various equipment technology levels, the requirements for mechanical structures are becoming more and more simplified, and fewer transmission parts are required, especially as parts for transmission boxes are becoming fewer and fewer. Mechanical transmissions are more directly driven, and The accuracy requirements are very high, which places higher requirements on the technological performance of horizontal boring and milling machines. Therefore, as a traditional boring shaft type structure, the machining target is decreasing. It will be replaced by a non-boring shaft type electric spindle, that is, a variety of parts will be processed by a high-speed machining center. Horizontal boring and milling machines are developing towards high-speed machining centers. On the one hand, the process is more adaptable, on the other hand, it also improves the performance level and machining accuracy. While increasing the scope of the machining process, various functional accessories are required as process guarantees. Boring, milling, drilling, tapping, attachment of CNC swing angle milling head accessories, and machining of various curved body parts. Equipped with a flexible work unit, which can exchange parts for batch machining.
The floor-type milling and boring machine mainly processes large and super-large parts with various profiles. Its process feature is equipped with a large floor-type platform (the size of the worktable is not limited), and it can process ultra-long and ultra-wide parts. At the same time, it can also be equipped with a rotary table, which can be used for rotary indexing and radial linear motion. Multi-sequence machining of parts can be completed by indexing, which greatly increases the technological scope. Now, the floor-type milling and boring machine produced by Italian company Pama (Pama) is specially equipped with a tilting and adjustable angle table, which further expands the machining range. High-power, high-efficiency cutting is a major machining advantage of floor-type milling and boring machines. The high-speed and high-precision technical requirements are increasingly affecting the technical development of floor-type milling and boring machines, and it is an important means to improve the technical level of floor-type milling and boring machines. Therefore, floor-type milling and boring machines are changing a single high-power, high-efficiency cutting, and more into the high-speed, high-precision process technology. Now, the ram structure has become the main structural type for high-speed milling and boring. The ram has a large cross-section, high rigidity, and high-speed operation stability. It is easy to install various milling head accessories for high-speed machining.
Development Trend
The development of heavy machine tools will present two major trends. On the one hand, the development direction is technically based on machining centers or large flexible machining units and large-scale composite machining machine tools. Among them, horizontal boring and milling machines will gradually be replaced by high-speed machining centers and flexible machining units; floor-type milling and boring machines to develop large-scale Combined composite machining centers are mainly composed of two or more hosts combined into a composite machining machine to meet the single-piece and small-batch production of large-scale machining parts. The technology is complex, the auxiliary time and the machining cycle are long. It is difficult for the machine tool to complete all the machining procedures, and it can be realized by two combined machining centers. For example: two CNC gantry boring and milling machines form a composite machining center and share the bed and guide rails, respectively with a rectangular table and a rotary table (indexing), which can perform boring and milling; a floor-type milling and boring machine and A CNC single-column vertical lathe constitutes a large-scale composite machining center, sharing the bed rail, with a floor platform and a rotary table, which can complete turning, boring, milling, drilling and other machining. The rotary table can be indexed. There are also many combined forms such as two large floor milling and boring machines sharing bed rails. This saves floor space, reduces costs, and improves machining efficiency. Another development trend is the pursuit of refined manufacturing, improving the technological content of equipment manufacturing, and reflecting the safety, environmental protection and humanization of machine tools.
In summary, the technology of contemporary horizontal boring and milling machines and floor-type milling and boring machines is developing very fast, which is mainly reflected in the update of design concepts and the improvement of machine tool operating speed and manufacturing process level. On the other hand, the structure of machine tools has changed greatly. The application of new technologies is endless. The structure of the horizontal boring and milling machine is developing towards the high-speed electric spindle, the floor-type milling and boring machine is developing towards the ram type (without boring shaft) structure, and the functional attachments are developing at a high speed, multi-axis linkage, and diversified structure types. This will be New trends in technology development in the coming period.