5 axis CNC machine
February 13, 2017 CNC Machine
Five-axis machining refers to the fact that there are at least five axes (three linear coordinates and two rotational coordinates) on one machine, and can be coordinated at the same time under the control of a computer numerical control (CNC) system. Five-axis machining machine with vertical, horizontal and cradle-type two-axis NC table, NC table NC dividing head, NC table 90 axis, NC table 45B axis, NC table A axis, two-axis NC spindle Types of. Five-axis CNC machine tools is a high-tech, high precision for the processing of complex surface of the machine, this machine system for a country’s aviation, aerospace, military, scientific research, precision instruments, high-precision medical equipment, Has a pivotal influence.
Table of content
Five-axis machining is a numerical control term, the machining is the NC machine tool axis at a certain speed at the same time to reach a set point, five-axis machining is five axes can be. Five-axis machining is a high-tech, high precision for the processing of complex surface of the machine, this machine system for a country’s aviation, aerospace, military, scientific research, precision instruments, high-precision medical equipment, etc. , Has a pivotal influence. Equipment manufacturing industry is the cornerstone of a country’s industry, it is the new technology, new product development and modern industrial production to provide an important means, is an indispensable strategic industry.
Five-axis CNC machine with vertical, horizontal and cradle-type two-axis NC table, NC table NC dividing head, NC table 90 axis, NC table 45B axis, NC table A axis, two-axis NC spindle Types of. The above six categories of seven kinds of five-axis machining has its own characteristics, can not say which form is better, can only say that your product is suitable for what type of five-axis processing.
(1) five coordinate machining double turntable machine
(A) Rotating coordinates have sufficient travel range, process performance is good.
(B) due to the structural constraints, swing the coordinates of the lower rigidity, as the whole machine rigid part of the rigid. The double turntable machine, turntable rigidity is much higher than the swing of the rigid, thereby improving the overall rigidity of the machine.
(C) to facilitate the development of a processing center. Only need to install a separate magazine and tool changer can be but double turntable turntable coordinate drive power, coordinate conversion relationship is more complex.
(2) five coordinate machining double swing head machine
Double swing head machine swing coordinate drive power is small, easy loading and unloading of the workpiece and coordinate conversion is simple.
(3) five coordinate machining a swing a turntable machine
The performance of a swing table machine is between the two.
1, can effectively avoid tool interference.
2, for the ruler surface parts, can be used side milling method knife.
3, the general three-dimensional surface, especially the more flat large surface, large diameter end mill can be used to close the surface of the surface processing.
4, can be a card on the workpiece on a number of surface space for multi-faceted, multi-process processing.
5, five-axis machining, the tool relative to the workpiece surface can be in the most effective cutting state. The error distribution on the surface of the part is even.
6, in some processing occasions, can use a larger size of the tool to avoid interference for processing.
4. Processing methods
1, point contact —- the most widely used five-axis machining type
The so-called point contact processing refers to the processing process to point contact forming the processing methods, such as spherical milling cutter, spherical grinding wheel grinding. The main features of this type of machining are: spherical surface normal vector pointing to the whole space, the processing of the surface normal vector has the ability to adapt, and line, surface contact processing compared to its programming is simple, less computationally, and as long as So that the tool radius is less than the minimum radius of curvature of the surface can avoid interference. So it is suitable for any surface processing. But because of the point of contact molding, cutting point in the cutting speed approaching zero, and thus poor cutting conditions, processing accuracy and efficiency is low.
2, surface contact type
The so-called surface contact processing refers to the face contact forming the processing methods, such as face milling (grinding) processing. The main features of this type of machining are: Since the cutting point has a high cutting speed, the cycle feed is large, so it has high processing efficiency and precision. However, due to the molding method and the shape of the tool, it is mainly suitable for the convex curve changes in the surface of the more flat processing.
3, line contact
Five coordinate machining NC processing current and future research focus.
The so-called line contact processing refers to the processing of the process of forming contact with the line, such as cylindrical Zhou milling, cone milling, camshaft drilling and belt grinding. This type of processing is characterized by the fact that the cutting speed is high at the cutting point, so that a higher machining accuracy can be obtained. At the same time, the machining efficiency is improved due to the contact molding. Has been developed to any curved surface contact processing research.
Five-axis machine tools, the workpiece is easy to clamp. Processing without special fixture, reducing the cost of fixtures, to avoid a number of clamping, improve mold processing accuracy. The use of five-axis machining die can reduce the number of fixtures used. In addition, due to the five-axis machine tool can save a lot of special tools in the processing, so reduce the tool costs. The five-axis CNC machine can increase the effective cutting edge length of the tool, reduce the cutting force, improve the tool life and reduce the cost. The use of five-axis machine tool processing mold can quickly complete the mold processing, fast delivery, better to ensure the quality of mold processing, mold processing becomes easier, and make mold modification easier. In the traditional mold processing, the general use of vertical machining center to complete the workpiece milling. With the continuous development of mold manufacturing technology, vertical processing center itself some of the weaknesses of the performance is more and more obvious. Modern die processing generally uses ball-end milling cutter to process, the ball cutter in the mold processing benefits are very obvious, but if the vertical machining center, then the bottom of the line speed is zero, so the bottom of the finish is very poor , If the use of four or five axis machining processing technology processing mold, you can overcome the above shortcomings.
6. Development trends
The current five-axis CNC machine tools in Europe and America, Japan as the representative of these countries, five-axis CNC machine tools represent today’s five-axis CNC machine tools the highest level of development. Well-known machine tool plant five-axis CNC machine tool technology development focus can be attributed to: high-speed, high precision, environmental protection, intelligence, composite. The torque motor is widely used as a rotary coordinate drive device, which makes the machine feed mechanism realize high speed, low loss, high precision and high efficiency.
The first is the use of linear motor drive technology. After ten years of development, linear motor technology has been very mature. Straight-line motors have just been developed to be susceptible to interference and heat generation problems have been resolved, and linear motor positioning technology, both in the high-speed mobile fast stop, there are some machine manufacturers to use damping technology to solve. Linear motor has the advantage of linear drive, no transmission chain, no wear, no backlash, so to achieve the best positioning accuracy. Linear motor with high dynamic, acceleration can be more than 2g. The use of linear motor drive also has a high reliability, maintenance-free features.
Followed by dual-drive technology. For a wider table or gantry type, if the use of intermediate drive, the actual can not guarantee the driving force in the center, prone to tilt, making the dynamic performance is poor. The use of dual-drive, dual-scale, a drive module, you can make the dynamic performance is perfect. A drive command, dual drive at the same time, the ruler to detect whether the two points are balanced, if not balanced by different instructions to achieve its balance. Of course, the development of five-axis CNC machine tool technology is far more than that, many of the technology in the DMG machine tool products will be reflected.
Five-axis CNC machining center
Machining centers are generally divided into vertical machining centers and horizontal machining centers. Vertical machining centers (triaxial) The most efficient machining surfaces are the top surface of the workpiece. The horizontal machining center can only be used to complete the workpiece Four sides processing. At present, high-end processing center is moving in the direction of five-axis control, five-axis machining processing center has high efficiency, high precision characteristics, the workpiece can be completed a five-face processing. Such as the configuration of the five-axis machining of the high-end CNC system, but also on the complex spatial surface of high-precision processing, more suitable for auto parts, aircraft structural parts and other modern mold processing. (Vertical vertical axis machining center in this issue) Vertical five-axis machining center There are two ways to rotate the rotary shaft of this type, one is the rotary table of the table. The table set on the bed can be rotated around the X axis, defined as the A-axis, A-axis general operating range +30 degrees to -120 degrees. The middle of the table also has a turntable, in the illustrated position around the Z axis rotation, defined as the C axis, C axis are 360 degrees rotation. This is done by combining the A-axis and the C-axis. The workpiece fixed to the workbench can be machined by a vertical spindle in addition to the bottom surface. A axis and C axis minimum index value is generally 0.001 degrees, so that the workpiece can be subdivided into any angle, the processing of the inclined surface, tilt holes and so on. A-axis and C-axis, such as with the XYZ three linear axis to achieve machining, you can process a complex space surface, of course, this requires high-end CNC system, servo system and software support. The advantage of this arrangement is that the spindle structure is relatively simple, the spindle stiffness is very good, the manufacturing cost is relatively low. But the general table can not be designed too much, load-bearing is also smaller, especially when the A-axis rotation is greater than or equal to 90 degrees, the workpiece cutting will bring a lot of carrying capacity of the table. The other is to rely on vertical spindle head rotation. The front end of the spindle is a rotary head, can be rotated around the Z axis 360 degrees, as the C axis, rotary head and can rotate around the X axis of the A axis, generally up to ± 90 degrees or more, to achieve the same function. The advantage of this setting is that the spindle machining is very flexible, the table can also be designed very large, the aircraft’s huge body, a huge engine shell can be processed in such processing center. This design also has a great advantage: we use the spherical milling cutter surface, when the tool center line perpendicular to the processing surface, the spherical milling machine vertex line speed is zero, the top of the workpiece surface quality will be poor, The use of spindle slewing design, so that the spindle relative to the workpiece through an angle, so that the spherical cutter to avoid vertex cutting, to ensure a certain line speed, can improve the quality of surface processing. This structure is very welcome by the mold with high precision surface processing, which is difficult to do the rotary table machining center. In order to achieve high precision rotary, high-grade rotary shaft is also equipped with a circular grating feedback, sub-degree accuracy within a few seconds, of course, this type of spindle rotation structure is more complex, manufacturing costs are higher.