Overview of the structural design of the most popu

The structural design concept of exechon parallel machine tool

analysis of the existing parallel machine tool

the kinematic parallel structure looks like many parallel "arms" with one end connected to each other and the other end connected to the base. This design requires that the joint points have invalid degrees of freedom (idof). The number of parallel arms of kinematic parallel machine tool (PKM) depends on its design (read the Patent Description) , the number of parallel arms varies, but no matter which design follows, flexibility and rigidity should be combined

due to its complex structure, difficult to manufacture, good rigidity, no gap and reasonable cost, the closed node has become a prominent problem of all parallel machine tools. This technical problem limits the number of parallel machine tools on the market, which is why the most successful design is those parallel machine tools with fewer joint points and less invalid degrees of freedom. Tricept is a parallel machine tool with the least joint points and invalid degrees of freedom, which also explains why Tricept can account for 70% of today's parallel machine tool market

analysis Tricept

the design of parallel machine tool is to make a movable box structure. From the perspective of viewing, this is very good, but the corresponding number of required invalid degrees of freedom (idof) has caused problems. Each joint point has more than one degree of freedom, acting like a universal hinge, and can only bear pure axial load, so the force must be absorbed additionally, such as by the central tube of Tricept

the biggest problem that appears on the central tube is that this force causes bending and torsion force on the central tube, and the combination of the two forces is very difficult to process and analyze the data easily. It is another difficult problem to process joint points with more than 2 degrees of freedom with sufficient rigidity and accuracy with multiple invalid degrees of freedom at a reasonable cost. And this kind of design has a negative impact on the rigidity of axial joint points, which will also seriously affect the overall rigidity

the concept of axcon

the design concept of the new axcon parallel machine tool solves all the problems of the parallel machine tool described above, and highlights all the goals of the parallel machine tool, such as high rigidity and excellent flexibility, and the combination of real-time display of temperature, deformation and other data, drawing curve dynamics. This new concept is: the degree of freedom of the lower joint point used is no more than 1 (1-DOF), and the brake with two stiffness (1-dos) is used, with linearity and bending in the same direction. The physical structure formed by this design can be completely solved. 3. Formulate correct and reasonable solutions to the problems, and exert the influence of deflection and torque forces on all parties of the machine tool

the design of exechon parallel machine tool solves the main problems in the structure of parallel machine tools in the past. For the first time, the parallel machine tool no longer relies on spherical nodes, highlighting all the goals of parallel machine tools, such as the combination of high rigidity and excellent flexibility and dynamics. This new concept is based on the use of the lower joint point with a degree of freedom of 1. The solid structure formed by this design can completely solve the influence of the deflection and torque forces applied to the machine tool

the design of exechon described here actually constitutes a pyramid shaped mobile tripod. This structure is through three 2-stiffness actuators connected to the rotating head. 1 Shandong Dongchen and Shandong Guangyin have both built 5000 ton/year pa1212 industrialized devices. The joint points with three degrees of freedom transmit the force to the platform without losing any rigidity. However, due to the influence of the angle of the joint point of the upper platform, it is possible to make the lower node is 1 degree of freedom only when the upper joint point of two actuators is 2 degrees of freedom and the upper joint point of the third actuator is 3 degrees of freedom. This design reduces the number of nodes and degrees of freedom of the whole parallel structure to 6 and 10

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