Update date:2017-11-11 Browse：5763
Parallel machine tool is developed on the basis of the principle of spatial parallel mechanism Stewart platform, is appearing in recent years, a new concept of machine tool, it is the product of parallel robot mechanism combined with machine, is the space agency, machinery manufacturing, numerical control technology, computer technology and the height of the CAD/CAM technology combining hard and soft of high-tech products. It overcomes the traditional machine tool series mechanisms tools can only along the fixed guide feed, homework degrees of freedom is low, the equipment machining flexibility and mobility is not inherent defects, which can realize multi-axis linkage nc machining, assembly and measurement of a variety of functions, can satisfy more complicated parts of special processing.
Known as the "machine tool of the 21st century", it has become the most alive new member of the machine tool family since its debut in the Chicago machine tool exhibition in 1994. 1 the characteristics of parallel machine tool as a whole, the traditional serial mechanism of machine tool, it is to belong to simple and complex machine, mathematics and relative, parallel mechanism of machine tool has simple structure and complex math, movement of the whole platform involves numerous mathematical operation, the result of virtual axis parallel machine tool is a knowledge-intensive organization. This new machine completely broke the traditional machine tool structure concept, abandoned the fixed guide rail way of cutting tool orientation, driven by the s parallel mechanism, greatly improving the rigidity of machine tool, machining precision and machining quality has improvement.
In addition, due to the improvement of its feed speed, high-speed and ultra-high speed machining is easier to achieve. Due to this kind of machine has high rigidity, high bearing capacity, high speed, high precision, and light weight, simple mechanical structure, low manufacture cost, high degree of standardization, got successful application in many fields, therefore received extensive attention of academia. The hybrid CNC machine, which consists of parallel and series, not only has the advantage of parallel machine tool, but also has more practical value in use.
With the continuous development of high speed cutting, the traditional tandem organization structure platform of structural rigidity and high speed mobile station gradually became the bottleneck in the development of technology, the parallel platform becomes the best candidate, and relative to the tandem type machine tool, parallel work platform has the following features and benefits: simple structure, low price. Machine mechanical parts number dropped sharply a tandem structure platform, mainly by the ball screw, hooke hinge, ball joint, servo motor, such as general components, these common components can be produced by specialized manufacturers, so the machine manufacturing and inventory costs was much lower than the traditional machine tool of the same function, easy to assemble and handling. High structural rigidity.
Due to adopt the structure of the seal (closed - loop structure) possesses the advantages of high rigidity and high speed, its structural load flow is short, and decomposition of load and pressure by six connecting rod at the same time, with material mechanics point of view, when the external force must, stress and deformation are maximum, the amount of cantilever ends insert (build) in second and then the Jane supported on both ends (simple - supported), followed by compression force structure, stress and deformation are minimum tension is the second force structure, so it has high rigidity. The stiffness weight ratio is higher than that of conventional CNC machine tools. High processing speed and low inertia.
Changes direction, if the structure of force (between tension and pressure), two force component will be the most saving material structure, and its moving parts weight is reduced to the minimum and at the same time by six actuator drive, so high speed machine is very easy, and have low inertia. High machining accuracy. Because of its multiple axis parallel mechanism of 6 telescopic rod length all alone on the location of the cutting tool and the attitude to work, so there is no traditional machine tool (that is, the series machine tools) geometric error accumulation and amplification phenomenon, and even average effect (averaging effect); It has the thermal symmetry structure design, so the thermal deformation is small. So it has the advantages of high precision. Versatility and flexibility.
Because the simple control mechanism is convenient, easier to object to be processed and designs the special machine tool, and at the same time developed into a general machine tools, can be used to implement the milling, boring, grinding, such as processing, can also be equipped with the necessary tools to make it of measuring machine, so as to realize the multifunction machine. This will bring great application and market prospect, and have a very wide application prospect in both national defense and civil service. Long service life.
Because the force structure is reasonable, the moving parts wear little, and there is no guide rail, there is no iron chip or coolant entering the guide rail, causing it to scratch, wear or rust. The Stewart platform is suitable for modular production. For different machining ranges of machines, it is easy to change the link length and the location of the connecting rod, and it is easy to maintain, without the need for the remaking and adjustment of the machine parts, simply input the new mechanism parameters. The transformation coordinates are convenient.
