Abstract: This article analyzes the basic principle of ultra precision of tapered rollers and introduces the design structure and installation method of the ultra precision guide roller adjustment detection device. This detection device can directly detect the height of the size end of the tapered roller, achieving rapid adjustment of the ultra precision machine.
Keywords: tapered roller; Ultra precision machine; Guide roller; Detection device
In the tapered roller bearings used for railway freight cars, logarithmic curve shape is preferred for the rollers, and it is required to add an ultra precision process to the logarithmic curve rollers after traditional grinding. To obtain the ideal roller profile, the adjustment accuracy of the two working guide rollers in the ultra precision machine is very high, and the working angle of the two guide rollers is difficult to measure directly. It is mainly obtained through multiple adjustments based on experience, which requires high skill requirements for the adjustment workers and is time-consuming and laborious.
1. Basic principle of roller ultra precision
The through method ultra precision tapered roller is shown in Figure 1. The rollers are conveyed by the feeding device to two ultra precision spiral guide rollers with spiral tracks. The working surfaces of the two spiral guide rollers are adapted to the roller cone surface. The spiral guide roller with a blocking edge pushes the roller ball base surface to achieve axial feed. The other spiral guide roller is made into a spiral shaped hollow groove at the corresponding blocking edge position to facilitate the alignment of the pitch at high speed. When two spiral rollers rotate at the same speed and in the same direction, the rollers undergo linear and rotational motion under the joint drive of the spiral roller cone surface and the retaining edge. At the same time, the oilstone achieves ultra precision grinding of the rollers under certain pressure and reciprocating oscillation conditions, as shown in Figure 2.
1- Ultra precision roller without edge guard; 2- Ultra precision roller with edge blocking; 3- Rolling track; 4- Edge blocking; 5- Roller; 6- Oil stone
Figure 1 Schematic diagram of the outer diameter surface of the through method ultra precision tapered roller
Due to the continuous process of roller penetration and ultra precision, almost no auxiliary time is required, and high-precision and high-quality rollers can be obtained in a short period of time, making it suitable for large-scale production. The general oil stone pressure is P=0.2-0.25 MPa, the amplitude is A=1-4 mm, the vibration frequency is 1500-2000 times per minute, and the speed is adjustable.
Figure 2 Schematic diagram of the contact state between the roller and the oilstone
The ultra precision machining of tapered rollers is divided into two types based on the different requirements of the roller profile: straight feed and oblique feed. The article only explains the logarithmic curve roller ultra precision oblique feed.
The contact point of the roller between the two guide rollers is the key to producing an ideal contour line (Figure 3). The optimal contact position between the roller and the guide roller is between points A and B. The support curve of the guide roller between points A and B must be hyperbolic. Under the current technological conditions, the establishment of the mutual relationship between guide rollers and tapered rollers mainly considers the following points: (1) the contact position between tapered rollers and guide rollers depends on the center of the tapered rollers; (2) Conical rollers with the same cone angle and axis can use guide rollers with the same angle for ultra precision;
Figure 3 Schematic diagram of guide roller adjustment
The influence of the outer diameter center of the tapered roller on the guide roller angle is relatively small, but this effect is more significant when the roller cone angle increases; Adjust the center distance a between the two guide rollers. As a increases, the center height of the small end of the tapered roller will be raised; When a decreases, the height of the large end of the tapered roller will be increased.
2. Guide roller adjustment detection device
2.1 Structural Design: The structure of the guide roller adjustment detection device is shown in Figure 4. The detection device needs to achieve movement in three directions, namely movement parallel to the axis of the guide roller, movement perpendicular to the axis of the guide roller, and up and down movement of the watch stand. The up and down movement of the gauge frame allows the dial gauge to come into contact with the tapered roller; The movement in the direction of the vertical guide roller axis can find the highest point of the taper roller line; The relative height of the highest point of the roller size end line in any spiral groove of the guide roller can be detected by moving along the direction parallel to the axis of the guide roller. This height value is an important basis for adjusting the guide roller.
1- Dial indicator; 2- Fixed clamp; 3- Adjust the knob; 4- Longitudinal moving rod; 5- Lateral moving body; 6- Horizontal adjustment knob; 7- Support platform; 8- Guide rail compression knob; 9- Guide rail; 10- Guide rail support
Figure 4 Schematic diagram of the structure of the raceway adjustment device
2.2. Installation method
The practical application of the detection device is shown in Figure 5. (1) The movement along the direction parallel to the axis of the guide roller is completed with the help of a linear guide rail. The linear guide rail is installed on the guide rail frame, which is connected to two magnetic gauge bases. With the help of the two magnetic gauge bases, the detection device can be attached to the guide roller frame of the machine tool. (2) To move along the direction perpendicular to the axis of the guide roller, a small support plate should be added to the linear guide slider, and the small support plate should be moved forward and backward by adjusting the bolt. (3) The up and down movement of the watch stand is achieved by installing a fine adjustment slider on the small support plate, attaching a miniature magnetic watch holder to the slider, and using adjustment bolts to achieve up and down movement.
Figure 5 Schematic diagram of actual use of the detection device
3. Actual usage effect
The schematic diagram of logarithmic curve tapered roller is shown in Figure 6. The curvature of the roller size end changes, and there are three requirements for convexity values. Taking the actual processing of 353130B logarithmic curve roller as an example, MEF-120 profilometer was used to measure and record the data, as shown in Table 1.
Figure 6 Schematic diagram of logarithmic curve tapered roller
Table 1 Roller Inspection Data
After more than a year of practical use, the designed guide roller adjustment detection device not only saves machine tool changeover adjustment time, but also ensures the quality of processed products, effectively solving the problem of rapid adjustment of ultra precision machines and achieving good results in use.
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