What are the structural features of boring and milling machines and milling and boring machines?

In recent years, the technology of horizontal boring and milling machine and floor milling and boring machine at home and abroad has developed very rapidly, which is characterized by the continuous updating of product structure, the endless application of new technologies, the compounding of process performance, the continuous improvement of speed and efficiency, and the emphasis on refined manufacturing.

The development of horizontal boring and milling machine has attracted much attention because of its concept of injection acceleration. Transmission components such as motorized spindle, linear motor and linear guide rail, which are supported by high-speed operation technology, have been widely used, pushing the running speed of machine tools to a new height. The innovative design of the machining center of horizontal boring and milling machine with replaceable spindle solves the shortcomings of the telescopic structure of motorized spindle and movable boring bar, and has the effect of compound machining and multi-purpose of one machine, which is also a major technological innovation of horizontal boring and milling machine.

The development of floor-standing milling and boring machine shows its elegance with its brand-new design concept, the trend of modern machining, the structure of ram without boring shaft with high-speed machining concept, and the exchange of various milling heads, which has a great tendency to replace traditional milling. Various milling head accessories represented by two-coordinate swing milling head have become the main means to realize high-speed and compound machining, with wider technological performance, higher power and stronger rigidity, which is a major breakthrough in the development of floor milling and boring machine.

Structural characteristics of 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 who adopt double-column thermal symmetry structure and put the headstock in the middle of the column. This structure is characterized by good rigidity, balance and good heat dissipation, which provides a reliable guarantee for the high-speed operation of the headstock. However, the double-column structure is not easy to maintain, which is why there are not many manufacturers in use today. The motion of headstock is mostly driven by ball screw driven by motor, which is the core transmission device of spindle drive. Most of them are supported by hydrostatic bearings, and servo motors drive ball screws. Because the spindle speed is getting higher and higher, the spindle temperature rises rapidly. Now many manufacturers will use oil mist cooling instead of oil cooling to control the temperature rise of the spindle more effectively and ensure its accuracy effectively.

There are two main structural types of spindle system. One is the traditional telescopic boring bar structure, which has the characteristics of boring deep holes and cutting with high power. The other is the modern high-speed motorized spindle structure, which has the advantages of high speed, high running speed and high precision.

The application of high-speed motorized spindle in horizontal boring and milling machine is more and more, which not only greatly improves the spindle speed and accuracy, but also simplifies the internal structure of spindle box and shortens the manufacturing cycle, especially for high-speed cutting, the highest speed of motorized spindle can reach more than 10000r/min. The disadvantage is limited power and high manufacturing cost, especially for deep hole machining. However, the speed of the telescopic structure of boring bar is limited, and its accuracy is not as good as that of the motorized spindle structure, but it can process deep holes with high power and high efficiency, which is incomparable to the motorized spindle. Therefore, the two structures coexist and have different technical attributes, but they provide users with more choices.

Now, a replaceable spindle system is developed, which has two functions. Users can choose to use it according to different machining objects, that is, the motorized spindle and boring bar can be used interchangeably. This structure takes into account the shortcomings of the two structures and greatly reduces the cost. This is a great innovation of today's horizontal boring and milling machine. The advantages of motorized spindle are fast cutting speed and fast feed speed, which greatly improves the accuracy and efficiency of machine tools.

The running speed of the horizontal boring and milling machine is getting higher and higher, the fast moving speed reaches 25 ~ 30m/min, and the highest rotating speed of the boring bar is 6000r/min. The speed of the horizontal machining center is higher, the rapid movement can reach 50m/min, the acceleration is 5m/s2, the position accuracy is 0.008 ~ 0.0 1mm, and the repeated positioning accuracy is 0.004~0.005mm.

Milling cutter of floor milling and boring machine;

Because the floor-type milling and boring machine mainly processes large parts, the milling range is wide, especially the high-power and powerful cutting is a great processing advantage of the floor-type milling and boring machine, which is also the traditional technological concept of the floor-type milling and boring machine. The technical development of contemporary floor milling and boring machine is changing the traditional process concept and processing method, and the concept of high-speed machining is replacing the traditional concept of heavy cutting, bringing about the change of high-speed and high-precision machining technology and method, thus promoting the structural change and technical level improvement of floor milling and boring machine.

At present, the biggest feature of the development of floor-standing milling and boring machines is the development of high-speed milling, all of which are ram-type (boring-free shaft) structures, equipped with various milling head accessories with different technological properties. The advantages of this structure are that the ram has large cross section, good rigidity, long stroke and fast moving speed, and it is convenient to install various functional accessories, mainly high-speed boring, milling head, two-coordinate double-pendulum angle milling head and so on. Reach the technological performance and processing range of the floor milling and boring machine, and greatly improve the processing speed and efficiency.

Traditional milling is processed by boring bar, while modern milling is mostly completed by various functional accessories through ram, which tends to replace traditional machining. Its advantages are not only the speed and efficiency of milling, but also the machining of polyhedrons and surfaces that can not be completed by traditional machining methods. Therefore, at present, many manufacturers are competing to develop and produce ram-type (boring-free shaft) high-speed machining center, which can greatly improve the technical level and scope of machine tools because of its economy and obvious technical advantages. At the same time, the machining accuracy and efficiency are improved. Of course, technical support requires different types of high-precision milling head accessories, and its requirements are also very high.

High-speed milling has brought structural changes to the floor milling and boring machine. The structure centered on the headstock is very common, with high rigidity and suitable for high-speed operation. The ram drive structure is driven by linear guide rail and linear motor, which is necessary for high-speed cutting. Foreign manufacturers have adopted it on floor-standing milling and boring machines, but there are few similar products in China, and linear guides are only used on small and medium-sized machine tools. High-speed machining also puts forward higher requirements for environment and safety, which leads to the concept of humanized production. All manufacturers attach great importance to the safety protection and operability of machine tools under high-speed operation, and implement a fully enclosed structure for the console and column, which is both safe and beautiful.

Process characteristics:

The traditional horizontal boring and milling machine is mainly suitable for machining various mechanical parts, especially mechanical transmission boxes and various curved parts. Due to the improvement of the technical level of various equipment, the requirements for mechanical structure are more and more simplified, and fewer transmission parts are needed, especially those used as transmission boxes. Mechanical transmission is mostly direct drive, and the precision of transmission parts is very high, which puts forward higher requirements for the technological performance of horizontal boring and milling machine. Therefore, as a traditional boring shaft structure, the number of machining objects is decreasing, and the non-boring shaft motorized spindle will be replaced, that is, the high-speed machining center will complete the machining of various parts. The development of horizontal boring and milling machine to high-speed machining center, on the one hand, has stronger technological adaptability, on the other hand, it also improves the performance level and machining accuracy. At the same time, various functional accessories are needed as process guarantee, which can not only bore and mill, but also drill, tap, install CNC pendulum milling head accessories and process various curved parts. Equipped with a flexible processing unit consisting of an exchange workbench, parts can be processed in batches.

The floor milling and boring machine mainly processes large and super-large parts with various surfaces. Its technological feature is that it is equipped with a large floor-standing platform (the size of the workbench is not limited), which can process ultra-long and ultra-wide parts. At the same time, it can also be equipped with a rotary table, which can perform rotary indexing and radial linear motion. Through indexing, multi-sequence machining of parts can be completed, which greatly improves the process scope. At present, the floor milling and boring machine produced by Pama company in Italy is specially equipped with a workbench with adjustable tilt angle, which further broadens the processing scope. High power and high cutting is one of the advantages of the floor milling and boring machine. The technical requirements of high speed and high precision are increasingly affecting the technical development of the floor milling and boring machine, which is an important means to improve the technical level of the floor milling and boring machine. Therefore, the floor milling and boring machine is changing the single high power and cutting mode, and more technical connotations of high speed and high precision are incorporated. At present, ram structure has become the main structure type of high-speed milling and boring, with large cross section, high rigidity and good stability in high-speed operation, which is convenient for clamping various milling head accessories to realize high-speed machining.

Development trend:

The development of heavy machine tools will present two major trends. On the one hand, machining centers or large flexible machining units and large combined compound machining machines are the development direction, in which horizontal boring and milling machines will be gradually replaced by high-speed machining centers and flexible machining units; The floor milling and boring machine mainly develops a large-scale combined compound machining center, that is, two or more hosts are combined into a compound machining machine tool, which is suitable for small batch production of large-scale machined parts and has the characteristics of complex process, long auxiliary time and long machining cycle. It is often difficult for one machine tool to complete all the processing procedures, but two combined machining centers can completely achieve it. For example, two CNC gantry boring and milling machines form a composite machining center, and the rectangular workbench and the rotary workbench (indexing) are respectively equipped with a lathe bed and a guide rail, which can be used for boring and milling; The floor milling and boring machine and CNC single-column vertical lathe form a large-scale compound machining center. * * * lathe bed guide rail, landing platform and turntable can complete turning, boring, milling and drilling, and the turntable can be indexed. There are also two large floor milling and boring machines * * * with bed guide rails and other combinations. This not only saves the floor space, reduces the cost, but also improves the processing efficiency. Another development trend is to pursue refined manufacturing, improve the scientific and technological content of equipment manufacturing, and embody the characteristics of machine tool safety, environmental protection and humanization.

To sum up, the technology of contemporary horizontal boring and milling machine and floor milling and boring machine has developed very rapidly, which is mainly reflected in the renewal of design concept and the substantial improvement of machine tool running speed and manufacturing technology level. On the other hand, the machine tool structure has undergone great changes, and the application of new technologies has emerged one after another. The structure of horizontal boring and milling machine is developing in the direction of high-speed motorized spindle, and the floor-standing milling and boring machine is developing in the direction of ram structure (no boring shaft). Functional accessories are developing in the direction of high speed, multi-axis linkage and diversified structural types, which will be a new trend of technological development in the future.