Numerical control method and research of bearing housing

Along with the rapid development of the national economy and the improvement of people's living standards, the demand for electricity from all parties is also growing, and the development and research of single-machine high-power steam turbines has been greatly developed. Therefore, the manufacture and installation of high-power steam turbines has become the main model at present, and the market share of supercritical 600WM and above units is increasing.

At present, the super-critical and ultra-supercritical unit bearing seats adopt spherical bearing structure to improve the matching precision with the bearing and reduce the vibration generated by the unit operation.

1 Spherical bearing housing machining accuracy analysis The bearing machining accuracy has a direct impact on the stability of the rotor operation; poor machining accuracy will cause poor bearing alignment, resulting in uneven load distribution, resulting in premature fatigue of the bearing due to edge wear. Failure; the bearing and the bearing housing are too loose, and slight sliding and micro-vibration may occur, resulting in wear on the back of the tile; the looseness is also unfavorable for heat transfer, which may cause the surface temperature of the bearing pad to be too high. For power generation equipment, the bearing and bearing housing are more rigid.

The bearing housing of the ultra-supercritical unit bearing housing adopts the following spherical structure. The advantages of the spherical bearing housing are as follows: the spherical surface of the bearing body is automatically adjusted to the center, and the neutrality is good, so that the bearing pads are evenly stressed and the edge wear is avoided; the spherical bearing housing structure can be Avoid the slight sliding caused by the looseness; make the contact surface of the bearing seat and the bearing body facilitate the scraping, and effectively ensure the contact area is not less than 75%.

2 Analysis of processing method According to the characteristics of the structure of the bearing seat, the bearing seat width is 280, the spherical diameter is “ball Φ1030+0.076-0.025”, and the empty sipe at the third, A, B and C in the lower casing is “0 ̄ 0.5+0”. .20 0". For example, in the ordinary boring machine processing, the forming tool is required, but because the bearing seat width and the spherical diameter are large, the contact area of ​​the cutting edge in the machining will be too large, which causes a large cutting resistance and affects the machining precision. At the same time, the size of the empty knife can not be processed.

Through the analysis of the structure, it is considered that the bearing housing structure is more convenient to process in the CNC machine tool, and the accuracy requirement can be guaranteed. The processing process is as follows: processing the ball cavity ??? go to the upper half of the bearing housing to process the empty sipe "0 ~ 0.5 + 0.20 0".

3 Machining program: For the machining of spherical bearing holes and empty sipe at the center line of 2# and 3# bearings () of a bearing housing of an ultra-supercritical unit, use a rotary table on the CNC boring and milling machine by programming CNC machining program. Machine the spherical bearing holes to complete.

The following is a description of the machining program with the 3# bearing housing as an example. The X-axis and the A-axis are the shafts for the flat-turn disc machining. The X-axis zero point is set on the 3# bearing center line, and the Y-axis and Z-axis zero points are set in the 3# bearing. At the center of the seat, the zero point of the A-axis is set at the inner hole of the diameter of “Φ1006”. The ball cavity is first processed, and the infeed point and the exit point can be calculated by drawing.

The key to the next step is to machine the 0.5~0.7mm empty sipe at the spherical bearing holes A, B, and C. Take the empty sipe at B as an example, and calculate the center of the flat disk through the 1, 2, and 3 points in the B-direction view. It is shifted downward by 3.768mm with respect to the center of the ball cavity, and the machining path is calculated through the 4, 5, and 6 points in the F-F cross-sectional direction, and the machining program is programmed to ensure the machining accuracy of the 0.5-0.7mm empty sipe required by the drawing. The machining axis zero point is the same as the above program zero point, but the Z-axis zero point offset during machining is added. The empty grooving machining procedure is as follows: N0005G54G60G90 N0010M42F100S200M03 N0015G59Z-3.768 N0020G16AXXA-(Fixed machining coordinate plane) N0025G00A-2.288X-120 Knife point) N0030G03A-2.288X120U491.062 (cutting point) N0036G00X-120 (retracting knife) N0040M30 (end of program) 4 Conclusion This paper introduces the advantages of the spherical bearing housing structure and the corresponding numerical control machining program data analysis, calculation and compilation method, Since the spherical bearing housing has better matching precision and self-position characteristics, with the continuous advancement of science and technology, the spherical bearing housing structure will be widely used.


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