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1、大连交通大学2008届本科生毕业设计（论文）外文翻译Development of the composite flexspline for a cycloid-type harmonic drive using net shape manufacturing methodThe flexspline for a harmonic drive must be flexible in the radial direction for the elastic deformation, but must be stiff in the torsional direction for accurate
2、transmission of rotational motion. Since these requirements cannot be satisfied simultaneously with conventional metals such as steel or aluminium, in this work the carbon fiber epoxy composite material was employed for the flexspline material in order to increase the torsional stiffness by tailorin
3、g the stacking sequence and to improve the manufacturing productivity by moulding rather than machining.The toothed composite flexspline was manufactured with the elastomeric cascade tooling that is composed of the steel tooth die, the silicon rubber mandrel and the cone-shaped steel core. Also, the
4、 steel flexspline with the same dimensions of the composite flexspline was manufactured by CNC wire cutting method.The static and dynamic performances of the composite flexspline and the steel flexspline were experimentally tested. From the test results, it was found that the developed composite fle
5、xspline had better flexibility in the radial direction and high damping capacity at the fundamental natural frequency.INTRODUCTIONThe harmonic drive is a special gear-drive speed reduction system whose operation principle is based on the elastic deformation rather than the rigid body motion of gener
6、al gearing system. It has many advantages, such as high speed reduction ratio, high rotational accuracy, high torque transfer per weight, high efficiency, little backlash and very compact size. Therefore, the harmonic drive is widely accepted in industrial robots and precision mechanisms. The three
7、basic components of the harmonic drive are the circular spline, flexspline and elliptical wave generator as shown in Fig. 1.The circular spline which has usually two or four more teeth than the flexspline operates in rigid body motion. The flexspline is usually designed as a thin walled cup-type sha
8、pe. The flexspline is composed of tooth, tube and boss sections as shown in Fig. 2.Figure 3 shows the principle of motion of the harmonic drive.As the ball-bearing mounted on the elliptical wave generator deforms the flexspline as shown in Fig. 3, the teeth of the flexspline on the major axis of the
9、 elliptical wave generator engage the teeth of the circular spline and the teeth of the flexspline on the minor axis disengage the teeth of the circular spline. If the rigid circular spline is fixed, the clockwise rotating of the wave generator produces the counterclockwise rotation of the flexsplin
10、e. If the circular spline has 102 teeth and the flexspline has 100 teeth, a single clockwise revolution of the wave generator makes the flexspline rotate counterclockwise through an angle comparable to two teeth. In this case, the rotational velocity ratio is 50:1.The flexspline of the harmonic driv
11、e that is the key element for the torque transmission has the contradictory dual role that must be flexible in the radial direction but must be stiff in the torsional direction to accurately transmit rotational motion. The conventional flexspline that is made of isotropic materials such as steel or
12、aluminium can not satisfy perfectly the contradictory dual role. Also, the motion of the harmonic drive is not perfectly smooth but has a ripple which has the same frequency as the wave generator. 4 The ripple can produce noise and vibration during operation.However, if the flexspline is manufacture
13、d using the carbon fiber epoxy composite material, many drawbacks of the harmonic drive can be eliminated, because the carbon fiber epoxy composite material has high specific stiffness, high specific strength and high material damping capacity. Therefore, in this work, the flexspline was designed an
14、d manufactured with the high strength carbon fiber epoxy material. The torsional stiffness was increased without increasing the radial stiffness by tailoring the stacking sequence and selection of the fiber orientation. The initial study on the development of the composite flexspline with carbon fib
15、er epoxy composite materials for the harmonic drive was carried out by Oh6 and Jeong.7 They manufactured the composite flexspline by adhesively joining the separately manufactured parts such as the boss, tube and tooth sections. Since the previous manufacturing methods required several labor intensi
16、ve operations, in this work, a new net shape manufacturing method for the composite flexspline was developed to increase manufacturing productivity. In this method, all the sections of the flexspline were made with carbon fiber epoxy composite material except the boss section.Since the involute tooth profile that is used in the conventional steel flexspline has a small curvature at the dedendum, the stress concentration at the root of the teeth is large when the fle
