Research and application of common gears in the main motion shifting system of CNC machine tools Zhang Xuewei Harbin University of Science and Technology, Heilongjiang Harbin 15,80 effect.

1 Introduction The main motion of CNC machine tools adopts electric stepless speed regulation by DC or AC speed regulating motor as power source. However, due to the large speed range of the main motion of the CNC machine tool, the speed control motor alone cannot meet such a large speed range; in addition, the power and torque characteristics of the speed control motor are difficult to directly match the power and torque of the machine tool. Therefore, the stepless speed-regulating motor is always connected in series to meet the requirements of the speed regulation range and torque characteristics. The design of the main motion shifting system of the CNC machine tool is combined with the ordinary machine tool step-variable transmission and the motor. After that, the requirements of the spindle torque and the stepless speed regulation range should be satisfied; the main motion step-variable motion should shorten the transmission chain as much as possible to improve the transmission stiffness; the volume of the main motion stepped shifting mechanism should be as small as possible. In the analysis of the main motion shifting system of the CNC machine tool, it is found that the use of the common gear is beneficial to the realization of the above requirements, and an unexpected effect can be obtained.

2 The characteristics of the common gear adopt common gears to reduce the number of gears in the shifting transmission mechanism and simplify the transmission mechanism. Therefore, it is widely used in the shifting system of ordinary machine tools. The use of a single common or multiple common gears does not prevent the series of speed series from forming, but since the common gear belongs to both transmission groups at the same time, the choice of transmission ratio is limited, especially when using multiple common gears. However, the transmission ratio has a stricter design and can be optimized. However, the application of the common gear in the ordinary machine shifting system is still limited. The reason is that the main motion of the ordinary machine tool is separately completed by the gear shifting mechanism, and the speed adjustment range is relatively large. Therefore, when the speed regulation stage is timed, the step ratio value is required to be smaller than the common ratio 9, and the common gear mechanism has the number of teeth between the shafts. The reason and difficulty in the displacement of the person in the same drive group is difficult to achieve.

Although the speed regulation range of the main motion of the CNC machine tool is large, the series gear shifting motion of the series gear after the stepless speed change is reasonable and small, which is advantageous for the common gear transmission.

3 The main motion design of CNC machine tool The AC main motion system with AC asynchronous motor is a constant power shifting system, but in actual production, it does not need constant power throughout the speed regulation range. The actual use of the machine tool is adjusted, and the statistics are generally required to calculate the rotational speed. The above is the constant power transmission, and the following is the constant torque transmission. This calculation of the speed is the minimum speed at which the spindle can deliver full power. The DC compound motor is used on the machine tool to adjust the armature voltage regulation from the rated speed to adjust the constant torque speed. The electromagnetic field current is adjusted from the rated speed to adjust the speed to constant power. Therefore, the torque and power characteristics required by the machine tool are similar. Generally, 4, and the motor constant power zone is smaller than the spindle constant power zone. Directly driving the spindle by the motor can not meet the requirements of the machine tool. It is necessary to drive the series geared transmission after the motor to achieve the requirements of the spindle torque and the stepless speed regulation range.

The following is an example of the design of the main motion shifting system of the CNC machine tool to illustrate the selection of its stepless speed range.

The maximum output power of the spindle speed melon spindle P stepless speed regulation selects the DC motor 2252, the rated power 13=7 rated speed=1500, the maximum speed, = 240, for example, the calculated speed 4=80 can also be determined. The motor range = 20, therefore, a stepped gearbox must be connected in series between the motor and the main shaft. The speed range of the mechanical shifting transmission is the scale machine. Because of the scale machine 8, a gear shifting mechanism composed of two shifting groups can be used. In the original transmission scheme, 2=4, from the ruler=1 to get = 1=2.37; now the 6-speed shifting mechanism composed of the common gear, ie 7=6, 1.68. The speed and power torque characteristics of the two transmission schemes And drive system, 1 and 2. respectively.

Under the same number of transmissions, the transmission mechanism with the common gear is more compact than the original transmission mechanism, reducing the volume of the transmission, shortening the axial length and increasing the rigidity of the main shaft.

4 Conclusions It is not difficult to see the calculation example of the main motion design of CNC machine tools. The common gear transmission mechanism can better realize the cooperation with the stepless speed regulation motor in the main motion mechanical shifting mechanism of the CNC machine tool; it can meet the spindle speed and speed regulation. The requirements of the range, at the same time, make the axial dimension of the spindle the shortest, and it is easy to ensure the rigidity of the shaft, which provides convenience for the gearbox design of the CNC machine tool and the overall structural design of the machine tool.

The machine tool design manual is written and edited. Machine Tool Design Manual, Volume 3 1. Mechanical Industry Press, 1996.

Liao effect, edited by Zhu Qizhen. Digital control machine tools such as. Huazhong University of Science and Technology Press, a original program; b new program

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