Key technologies and application prospects of mill-turn compound machining

Qiqihar No.2 Machine Tool (Group) Limited Liability Company Qiqihar, Heilongjiang 

Abstract: The eternal goal pursued in the field of metal processing is machining efficiency and precision. CNC technology, computer technology, machine tool technology, processing technology continues to develop, the traditional processing concept can no longer meet the processing speed, efficiency and accuracy requirements. In this context, the emergence of composite machining technology. Generally speaking, composite processing refers to a processing equipment, to complete different processes or different machining methods of processing technology. Nowadays, the composite processing technology mainly presents two different types, one is based on the combination of different processing methods of energy or motion mode, and the other is based on the principle of process concentration, based on the machining process.Mill-Turn MachiningIt is one of the processing methods that have developed very rapidly in this field in recent years.

Keywords: mill-turn machining; key technologies; recommendations;

At this stage, aerospace product parts are diversified, with small quality, complex processes, and raw materials for overall thin-walled structures. In view of the complexity of the process, material selection and processing are also correspondingly complex, and in small quantities, which results in relatively long production cycle times, extremely stringent selection of materials, resulting in large amounts of material removal, and low machining efficiency, among other things. In order to improve these problems and to enhance the efficiency and precision of aerospace products, engineers continue to search for the best machining methods. The development and application of combined turning and milling machining equipment provides a good way to solve these problems.

First, the development and characteristics of turning, milling composite processing

Turning and milling technology is an advanced machining technology that replaces turning tools with milling tools to cut rotating parts. Depending on the difference in the relative position of the tool axis and the workpiece axis, turning and milling can be divided into axial turning and milling, and orthogonal turning and milling. Turning and milling movement belongs to the composite movement, this movement with the help of milling cutter rotation and workpiece rotation of the joint movement can be achieved. Turning and milling is not simply a combination of turning and milling approach, but the use of turning and milling of the integrated movement to complete the processing of various types of surfaces. In the turning and milling cutting process, the workpiece is not required to carry out high-speed rotation, the main rotary motion is completed by the movement of the tool, so it can not make the workpiece high-speed rotation to achieve high-speed cutting, which is beneficial for large rotating body for high-speed cutting workpiece, and for the realization of the difficulties of the dry cutting processing material is also helpful. Based on the machining characteristics of turning and milling, turning and milling are intermittent cutting, and this type of cutting is extremely suitable for cutting chip materials that are difficult to cut. By turning and milling to achieve high-speed processing, usually deal with interfaces and milling machining centres, such as HSK, CAPTO high-speed processing, high-speed cutting tools and workpiece rotation speed is lower than the previous situation, resulting in the cutting force is far less than the traditional type of machining, this state is extremely suitable for thin-walled parts of the machining process, and also will not be triggered by the thin-walled workpieces. This is ideal for machining thin-walled parts, and there is no risk of thin-walled parts becoming thin due to the centrifugal force factor and deformation caused by high-speed rotation.

Second, the key technology of turning and milling composite processing

A technology called turning and milling composite processing, composite processing which is the most representative of the characteristics of the machining process is concentrated, so the scientific and reasonable processing methods and process progress, is the core elements of turning and milling composite machining technology to continue to improve and develop, to take a milling machine car composite machining centre, the machine tool with five-axis milling, turning, boring, drilling, sawing, automatic feeding and other functions, the use of FANUC 31i CNC system, especially suitable for high-speed precision machining of shafts, rotary parts, in the processing of aviation impellers, using the S192F milling centre. After the execution of all processes and subsequent processing, this mode can be used for single card loading. The entire process does not require human intervention, but is carried out by the machine itself. The integrity of the process is guaranteed, which greatly improves accuracy, reduces product errors and saves production costs.

2.CNC programmingTechnology, involving turning and milling composite machining. The development of turning and milling compound machining technology puts forward higher requirements for CNC programming technology, which is also a bottleneck for turning and milling compound machining equipment in actual production and application. In actual production, turning and milling compound processing due to the application of a short period of time, the lack of professional compound machining solutions, processing procedures are usually part of the plan, with the help of general CAM software, followed by manual process personnel will be integrated into the programme to meet the requirements of the compound machining machine tool machining program. This type of solution is very demanding on the craftsmen. Compared to traditional CNC programming techniques, the difficulties in programming for turning as well as milling complex machining are mainly in the following areas. Firstly, the variety of processes. For craftsmen, turning and milling composite processing technology is extremely difficult to apply, need to master CNC turning, milling, drilling and other types of processing methods, for more than one process before the link as well as the mastery of the extremely strict standards. In the process of CNC programming, to have a good understanding of the current operating process and grasp, for the process to be implemented, easy to concentrate on the overall control and programming. Second, at the time of programming, serial or parallel order must be strictly in accordance with the process route to determine. In the mill-turn composite machining line, can achieve a variety of parts from raw materials until the finished product of a one-time processing, but the processing process to ensure that the CNC programming with a high degree of conformity with the process, the combination of multiple processes can and should be in accordance with the complete CNC machining programme to be considered comprehensively, so the achievement of composite machining process should be followed by the process - conversion - Simulation of the integration of process execution planning, integration of machining procedures, in accordance with the domestic discussion, it can be seen that turning and milling composite machining of CNC programming is quite difficult, the process is more complicated, at present, the CAM software to deal with a number of problems to be dealt with by engineers.

1. Turning and milling compound processing, post-processing technology exists. 2. between the different processes, the articulation of the movement requires strict accuracy. 3. firstly, it is necessary to set up a scientific and reasonable way of entering and exiting the tool, as well as the coolant switching off time, and the time of the automatic tool change, etc. 4. secondly, in the realisation of the machining of a process, it is necessary to unify and integrate the rest of the parts of the movement. 5. to ensure the stability of the other parts in a process, to avoid the impact of friction and collision between parts. 6. the process sequence and CNC program need to be determined automatically. The stability of other parts in a process, to avoid the impact of friction and collision between the parts. 6. The process sequence and the CNC programme, need to be automatically determined. In post-processing, the sequence of machining and changes in tool positions can be determined automatically, and changes can be made automatically according to the programming to set up the subsequent machining process. Each part of the programming should be carefully analysed and interpreted when writing the CNC programming content. For example, the tool position information covers the machining method, as well as the tool position information and the machining sequence, including the type of tool used and the tool number. The subsequent discharge process facilitates the determination of the sequence, method and tool. Post-processing techniques vary. The post-turn-mill process needs to be capable of multi-axis CNC milling. It also needs to be able to achieve turning and drilling. And to be able to achieve machining and healing and also sawing. And also be able to implement automatic feeding, and be able to implement tail control circuits. And can achieve the function of the programme call, and then the back of the turning and milling processing algorithms, basically encompasses the existing CNC processing of various processing methods. And can achieve seamless integration between different processing methods and movements.

Currently there are turning and milling composite machining simulation technology, as a path to enhance the application level of turning and milling composite machining, but also to improve programming efficiency, so it is necessary to promote the application of simulation technology, at present, and Gibbs company's output of the software is the main software for turning and milling composite machining simulation, but this type of software is usually expensive, and is rarely used in China's aerospace manufacturing industry. Put into use, in fact, milling composite machining simulation with the help of the current general CNC machining simulation software (such as , and so on) can also be achieved, based on the structure of milling composite machining equipment, the characteristics of the movement, the special features and CNC system, relying on the custom function as well as the macro-development to achieve the machining process of motion simulation.

5. Attention to the cultivation of talents, composite processing equipment is now the embodiment of cutting-edge technology in the field of machining, whether it is process planning or operation and maintenance are more complex compared to conventional equipment, high-level R & D team is to reach the core of the healthy and efficient operation of the equipment.

Third, the development prospects of turning and milling technology

Turning and milling belongs to high-efficiency and high-precision machining methods, but in view of milling processing, with the help of four-axis or five-axis linkage processing, so its trajectory is extremely complex, the traditional manual programming is difficult to detect the milling and turning CNC programming, as well as CAM software programming readability is poor, in the change of the code generated by the post-processing, so in the field during the operation of the situation varies. Today each turning and milling machining centre equipment manufacturer has its own set of turning and milling machining macros, which are not very versatile, like the standardisation of manufacturer macros, more like cam, crankshaft, and chamfering macros for cylindrical intersecting holes, and subsequently turning and milling machining technology can be developed rapidly. Milling cutter for turning is not as common as the general milling cutter, this milling cutter mainly by means of turning and milling to carry out machining operations on rotary parts, so its forefront of the front angle and the back angle, as well as the blade angle, the main front and the sub-cutting edge, are different from the ordinary milling cutter, even if there are a number of manufacturers of cutting tools for automotive milling cutter, but the high speed and high precision turning and milling cutter is still a further development of the milling cutter. Even though there are some manufacturers of tools for automotive milling, high speed and high precision turning and milling cutters are still a limitation for the further development of milling. The development of milling and turning technology would be faster if there were a wider variety of tools and a wider range of options. With the development of CNC programming, machining simulation and milling tool technology, the future of turning and milling technology will be even more promising.

At this stage, composite processing equipment is moving towards a larger processing range, higher efficiency, scale and modularity, which is the current situation. Aviation product manufacturing field has always been the key stage for advanced manufacturing technology to play a role. With the aviation product upgrading continues to accelerate, the process of dispersed processing equipment will gradually be process concentration of flexible automation equipment to replace, and this for the development and application of composite processing technology provides a broader space.