Hybrid bearing absorbed the advantages of static and dynamic pressure bearing, abandoned the two bearing faults. It used has surface shallow cavity oil wedge structure, using static pressure bearing of throttle principle, make pressure oil cavity in the produced enough large of static pressure axis hosted force, make spindle in is not rotating Shi on can floating up, to overcome has liquid moving pressure bearing started and stopped Shi appeared of dry friction caused spindle and bearing wear phenomenon, improve has spindle and bearing of using life and the precision keep sexual, and due to surface natural throttle, no has static pressure bearing in the throttle Manager plug of plagued, using reliable. After the Spindle On, rely on shallow cavity formation of ladder effect of dynamic pressure bearing and hydrostatic bearing overlay and vastly improved spindle bearing capacity, and multiple reset the structure and greatly increases rigidity of spindle; homogenization of high pressure oil film and good resistance to shock, ensure the spindle has a high running accuracy and smoothness of operation. High rigidity, vibration resistance performance is good, almost without friction and wear, and to maintain the long-term use of precision, bearing flow compared to the minimum required, simple structure, easy to replace.
Basic steps are as follows:
1, grinding boring head housing bore. Spall and refinements of the grinding Rod after cleaning, boring and grind the head should be placed in a vertical position. Housing bore requirements after grinding head roughness Ra<0.32 μ m, column 0.004mm.
2, determine the location of oil boring heads, boring, tapping.
3, ordering the bearing outer circle size 0.3~0.4mm nominal amount of grinding to ensure the arrow holes meet the needs of. After grinding and housing bore keeps 0.006~0.008mm clearance, to ensure that bearings with cylindrical bore of the coaxial, equipped with bearings cylindrical grinding requirements when mounted on a mandrel taper is less than 1:10,000. Bearing when mounted mandrel, Gary pushed, not with a blunt object into the, in order to avoid deformation of the bearing and bearing damage. When removing, hot out of hot water the hot bearing, easy and secure. To facilitate bearing mounting the housing bore, can go into the holes in the bearing end mill small diameter 0.05mm, 10MM taper the width.
4, bearing cylindrical distribution after grinding is complete, a rigorous cleaning with clean kerosene or gasoline, and then mount the bearing bore holes. Arrow end bearing surface distance around 5mm. When the bearing is installed too tight, and not forced into, you should check the following: ① bearing is mounted, ② the clearance is too small, ③ bearing rounds and boring head bearing hole is there dirt or burrs.
5, installation and cleaning oil system. Bearings are installed, according to the information provided by the manufacturers install circuit. When cleaning oil, the oil supply system is connected to the supply and return pipe, start the oil supply system, loop wash. Then connect the bearing oil, again starting fuel supply system for the entire bearing oil system cleaning and observation hole injection into oil in the bearing even and symmetrical, to detect hydraulic system problems.
6, boring and grinding head spindle. To ensure the original spindle boring head is still used, order on behalf of the inner diameter of the bearing size to reduce 0.2mm. Distribution according to the bearings of spindle grinding. Enjoy grinding spindle front should complete a center hole, ensure the spindle shaft and flange runout is less than 0.003mm. Spindle and bearings and enjoy grinding gap size should ensure 0.028mm. Rear axle diameter of the cylindrical grinding-0.003mm distribution, surface roughness Ra ≤ 0.161 μ m.
7, install spindle. Spindle after clean install, put out the oil system and bearing cleaning oil, provisions on transfer of lubricating oil, connected to all the oil, loosen the relief valve, starting the pump operation. Adjust the relief valve, fuel pressure is 1.2 per cent to 2.0MPa, check the two bearing oil cavity pressure, should generally be between 0.6 to 1.5MPa. Rotate the shaft by hand, easily without blocking normal, as spindle rotation when the oil supply for the best.
8, the trial run. Bearing part of the installation has been completed, equipped with pulleys and belts, adjust the belt tension (not too tight), note that this should be done in open state of oil supply system, so as not to damage the spindle and spindle hole. Check the oil pressure and the bearing cavity pressure necessary to meet the requirements in the 7th, turn the spindle to see if light. If there is no exception to start the spindle motor spindle running, the bearing pressure due to the effect of dynamic pressure in the cavity will have a more significant rise, usually spindle does not rotate when the pressure of two or three times. Trial run after the LH base tends to a constant oil temperature, without the boring bar can be installed try processing the exception.
9, try processing tests. In accordance with technical requirements for trying. Upon examination, the roundness of the bearing bore from 0.05mm to 0.005mm, straight from 0.01mm down to 0.005mm, surface roughness is lower than Ra0.16 μ m.
Transformed boring of connecting rod after several years of running shows that to good effect.
1, to improve the machining precision level.
2, reduced bearing surface roughness levels.
3, increases machine productivity, reduced downtime repairman? 60h. Single-link reduced processing time by half.
4, extend the life of the spindle and bearings, is expected to use a maintenance free period of nearly 10 years.
5, saving the large bearing replaced repair costs or purchase of new machine tools, good economic results.
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