Modeling with five axes (5 -axis machine), as its name suggests, a model for treatment for CNC machines. The linear interpolation movement of 5 coordinates in X, Y, Z, A, B and C is adopted. But do you really know the treatment at five axes?
The development of five -axes technology
For decades, people generally believe that five -axis CNC treatment technology is the only means of continuous, smooth and complex curved surfaces. Once people encounter insoluble problems in the design and manufacture of complex surfaces, they will help treatment technology with five axes. but. Petrol Petrol Linding at five CNC axes is the most difficult and most used technology in CNC technology. Use internationally, CNC Liaison technology with five axes as a sign of the level of automation technology for production equipment. Due to its special status, in particular for the significant impact of aviation, aerospace and the military industry and technological complexity, the developed countries of Western industry have always implemented the system CNC in five axes as a license system for exporting strategic equipment. Compared to the link to three axes, from the point of view of the process and the programming, the use of CNC treatment at five axes has the following advantages for complex curved surfaces: 1) Improvement of quality and efficiency Treatment 2) Expansion of the scope of process 3) Define a new development of the composite development department
But haha, but still. Essence petrol due to control of interference and tools in the treatment space, CNC treatment with five axes is much more complicated than the three -axis machine tool. Therefore, the five axes are easy to say, and it is really difficult to do it! In addition, it is more difficult to use it!
Speaking of the five axes, I must say that the five axes of the real and the false? The difference between the True and Faux 5 axes is whether there is an RTCP function. RTCP, explain, Fidia’s RTCP is an abbreviation for the “center of rotation tools”, which literally means “rotation tool center”. The RTCP of PA is the abbreviation of the first words “rotation of the center of tools in real time”. Heidehan described the SO-appeal upgraded technology of TCPM, that is to say the abbreviation of the “management of the tool center” and the central management of tools. Other manufacturers are called TCPC, which is the abbreviation of the “control point control of the tool center” and control of the central point of the tool. From the literal meaning of the Fidia RTCP, supposes that the RTCP function is carried out in a manual way, the real point of contact of the central point of the knife and the surface of the tool and the surface of the room will remain unchanged. Line, the knife handle will revolve around the center of the tool. In order to achieve the goal of simply surrounding the target trajectory point (that is to say the central point of the knife) when the RTCP function is executed, it is necessary to compensate for the lag of each right coordinate of The set of tools of tools caused by the rotation of the handle. The effectiveness of the tool and the part and effectively avoids interference. Consequently, RTCP seems to be more at the central point of the knife (that is to say the target trajectory point of the control control code) to deal with the change in rotary coordinates. Machine-tools with five axes and CNC systems that do not have RTCP must rely on cam programming and post-procedure. A false axis at five. Of course, it is understandable to be called a five -axis link, but this (false) axis with five axes is not the other five axes (real)!
The publisher also consulted industry experts. ! It’s a popular saying, not a standard saying. The five -axis positioning treatment. Mode can also be understood as a fake axis at five.
The shape of the CNC machine with current five axes
In the mechanical design of the 5-axis treatment center, manufacturers of machine tools have always persisted in developing a new sports mode to meet various requirements. Based on the current five-axis machine tools on the market, although its forms of mechanical structure are diverse, there are mainly the following forms:
Two rotary contact details directly control the management of the axis of the tool (double swing head)
The two coordinated trees are at the top of the tool, but the rotary tree is not vertically perpendicular to the right axis (lying headrest)
Two rotary contact details directly control the space spin (double -round table form))
The two coordinate trees on the Ouchette, but the rotary tree is not perpendicular to the right axis (drilling workshop)
One of the two rotating coordinates is on the tool, and the other saw the machine-tools on the room (a swing, a turn). exercise.
The difficulty and resistance of the development of CNC technology at five axes
Everyone has already recognized the superiority and the importance of CNC technology in five axes. But so far, the application of CNC technology to five axes is still limited to a small number of funds, and there are still problems that have not been resolved.
Did the following publishers have collected difficulties and resistance to see if this corresponds to your situation?
The abstraction of CNC programming in five axes and the operating difficulty. The three-axis machine has only a line of right coordinates, and the structure of CNC machine tools with five axes is diversified; A certain machine tool with five axes cannot be applicable to the NC code of a machine tool with five axes. In addition to the straight line movement, the CNC programming must also coordinate the relevant calculations of the rotation movement, such as the inspection of the rotary angle, the nuclear of non -linear error and the calculation of the rotation movement of the knives. CNC programming is extremely abstract. The functioning of the CNC treatment with five axes is closely linked to programming skills. Only repeated practice can program and operators master the necessary knowledge and skills. The absence of experienced programming and the lack of operators is a major resistance for the popularization of CNC technology with five axes. Many national manufacturers have bought CNC machine tools at five axes abroad. Many opportunities are not as good as using three-axis machine tools. The movement of the NC interpolation controller and the Servo driver system is very strict. The addition of rotating coordinates not only increases the burden of interpolation computer science, but also the small error of the rotary coordinate will considerably reduce the treatment accuracy. Therefore, the controller must have higher computer precision. The movement characteristics of the five-axis machine tool require that the Servo pilot system has good dynamic characteristics and a high-speed regulation range.
The verification of the NC program at five axes is particularly important
In order to improve the efficiency of mechanical treatment, it is urgent to eliminate the traditional verification method of the “test cutting method”. In the CNC treatment at five axes, the work of verifying the NC program has become very important because the price of the treatment of the part of the CNC machines at five axes is generally very expensive, and the collision is a common problem in the CNC treatment Five axes: the tool was cut in the knife room; In the CNC at five axes, it is difficult to predict the collision. If the CAM system detects an error, the trajectory of the knife can be treated immediately; But if the NC program is false during treatment, the trajectory of the knife cannot be directly modified as in the three -axis CNC. On the three-axis machine tool, machine tool operators can directly modify settings such as the tool department. In the treatment at five axes, the situation is not so simple, because the changes in the size and position of the tool have a direct impact on the trajectory of subsequent rotation movement.
Compensation of the knife radius
In the NC liaison program with five axes, the tool length compensation function is always valid, while compensation for the radius of the tool is not valid. When cylindrical friction is contacted for training and milling, different procedures must be prepared for tools with different diameters. Currently, the Popular CNC system cannot complete compensation for the radius of the tool, because the ISO file does not provide enough data to calculate the tool’s position position. The user must frequently change the knife or adjust the exact size of the tool during CNC treatment. Consequently, the entire processing process is very effective. In response to this problem, Norwegian researchers develop a temporary solution called LCOPS (optimal production strategy optimized at low cost, low in optimal consumption). The required data required by the trajectory of the tool is transported to the CAM system by the CNC application, and the transporter trajectory of the calculated cutter is directly sent to the controller. LCOPS requires a third party to provide CAM software, which can be connected directly to the CNC machine. The final solution of this problem depends on the introduction of a new generation of CNC control system, which can identify the part model (such as STEP, etc.) or CAO system files in general formats.
Rear processor
The difference between the five -axis machine and the three -axis machine is that it also has two rotating coordinates. Using the popular rear processor generator on the market, you just have to enter the basic parameters of the machine tool to generate the rear processor of the CNC machine with three axes. For the CNC machine with five axes, there are currently only improved rear processors. The rear processor of the five-axis CNC machine-tool should be developed.
When the three-axis link, it is not necessary to consider the point of origin of the part at the location of the machine tools in the tool trajectory. The machine tool. For a five -axis link, for example, when treating a horizontal grinder with five five axes of X, Y, Z, B and C, the size of the location between the part on the C -TO and the position size between B and C to each other. Workers generally spend a lot of time to cope with these location relationships during the installation of workers. If the rear processor can process this data, the installation of the part and the handling of the tool trajectory will be considerably simplified; The rear treatment Treatment The device can obtain the appropriate NC program after the trajectory of the knife 迹.
Non -linear errors and strange problems
Due to the introduction of rotating coordinates, the athletics of the CNC machine with five axes is much more complicated than the three -axis machine. The first problem related to rotation is non -linear errors. Non -linear errors must be attributed to programming errors and can be checked by shrinking the distances of PAS. During the Pre-Calculist phase, the programmer cannot know the size of the non-linear error. The linearization of the tool trajectory can solve this problem. Some control systems can line up the tool trajectory during processing, but it is generally linearized in the rear processor. Another problem caused by the rotary axis is strangeness. If the strange point is at the limit position of the rotary axis, if there is a small oscillation near the strange point, it will rotate the rotary tree at 180 °, which is quite dangerous.
CAD / CAM requirements
For the operation of the five – -factor machining, users must use the mature CAD / CAM system, and they must have experienced programmers to operate the CAD / CAM system.
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