2011年6月29日星期三

Ultra-precision Grinding Machine with a Common, low-roughness Part





Large-scale construction machinery factory grinding surface roughness Ra0.02 - 0.04μm, accuracy h4 - h5 of the journal, the expensive high-precision grinding machines are on. But the general construction machinery factory did not build high-precision grinding machines, grinding out to be such a low surface roughness, the journal such a high accuracy is very difficult. We have existing equipment M131W ordinary cylindrical grinder on a lot of testing, and exercise the necessary testing, scraping and adjusted by trimming and fine balance wheel, the abrasive on the whole more suitable micro edge contour , they can achieve ultra-high precision, low roughness of the grinding pin, effectively grinding the accuracy h4 - h6, roughness Ra0.02 - 0.04μm parts. The method is simple, convenient and easy, the effect is quite good.
2 ultra-fine grinding mechanism
Ultra-fine grinding wheel working surface can be trimmed by a large number of high-abrasive micro-edge of this feature and can be carried out. The high micro-blade removal from the work surface meager, still has some traces of defects and micro-shape and size and margin of error. Therefore, the use of these and other micro-cutting is a lot, and if appropriate the amount of grinding, the surface may be left behind in processing a large number of very fine cutting traces, so the available low surface roughness. In addition, in the absence of fire since spent grinding stage, there is still very clear to the friction, slip extrusion, and calendaring and so polished, so that was the secret process to further reduce surface roughness.
Three pairs of normal maintenance grinding
In order to work on grinding out grinding roughness Ra0.02 - 0.04μm workpiece, grinding should be flexible as the old test project does not meet accuracy requirements, will have to be scraping maintenance.
(1) bed rail maintenance
1) how to detect and V-shaped scraping bed rails: in the vertical plane of Non-straightness in the 1m length shall not exceed 0.01mm; in the horizontal plane of Non-straightness in the 1m length shall not exceed 0.01mm; saddle rails with no vertical slip degree in 250mm length shall not exceed 0.02mm; point of contact requires 12 - 14 points (25 × 25) mm.
2) testing how scraping flat bed rail: V-shaped rail of the degree of inequality in the 1m length shall not exceed 0.02mm; in the vertical plane of Non-straightness in the 1m length, the method was more than 0.01mm ; contact with spots requiring 12 - 14 points (25 × 25) mm.
(2) maintenance slide rails saddle
1) how to detect and V-shaped scraping slide saddle rails; not in the vertical plane straightness, all length shall not exceed 0.01mm; touch spots requires 10 - 12 pm (25 × 25) mm.
2) testing and what level scraping slide saddle rails: V-shaped rail is not parallel, the total length should not exceed 0.02/1000mm; touch spots requires 10 - 12 pm (25 × 25) mm.
(3) adjusting the grinding wheel spindle and bearing clearance
In the paint on the grinding wheel spindle shaft and bearing transfer research, with a bearing scraper scraping table containing surface, the contact spot should reach point 12 - 14 points (25 × 25) mm, then the installation and adjustment, the grinding wheel spindle and bearing the gap adjusted to 0.0025 - 0.005mm. This can be overcome in the grinding of the workpiece edge appears circular defects.
(4) spindle motor and wheel balance wheel
As the grinding wheel spindle motor vibration on the surface roughness of great influence, so the grinding wheel spindle motor need to go through a balance wheel balance should be carried out twice; wheel dressing with a diamond pen after a rough balance, and then Whetstone or after roughing trimmed by the fine grinding wheel to do a fine balance.
4 fine, fine twice what the entire wheel
For grinding a surface roughness of the workpiece to achieve Ra0.02 - 0.04μm, using the following two methods to work fine, fine grinding wheel dressing twice.
(1) finishing with diamond pen, and then fine-fine grinding wheel after the car repair round, to meet the surface roughness Ra0.4 - 0.8μm requirements, to grinding out Ra0.02 - 0.2μm is very difficult . If, however, finishing with a diamond pen, the rear wheel and then fine fine repair, you can meet this requirement.
Small repair can be used when TL60 # ZR1 - ZR2 wheel diameter φ100mm so. In a first mandrel wheel clamp, and then finish turning lathes in precision cylindrical, to eliminate deflection. Repair after the fine-grinding wheel, grinding wheel that is fine with grinding wheel business.
Finishing grinding wheel with a rotation by the head frame, its speed is lower, the Ministry of Trade 80--100r/min, feed when a small, back and forth once the Ministry of Trade 0.002mm, table reciprocating motion slower than 0.3m/min , subject to appropriate the whole back and forth several times. Wheel dressing and the dressing wheel rotate in the same direction, namely the two points of contact line speed in the opposite direction. Coolant to the full, in order to float the sand wash away, to prevent the process of grinding the surface with floating sand nap.
After fine grinding, fine trimmed twice in the abrasive wheel can be repaired more of the high micro-blade, grinding wheel after wheel dressing was removed and then brush the surface of the sand. Before grinding, the coolant should undergo strict filtering. Grinding, the coolant to the full, to prevent the burn surface.
(2) finishing with diamond pen, and then repair fine whetstone
First with a sharp single-particle diamond pen intensive, large abrasive wheel repair can be more of a micro-blade high, then Whetstone (or sand) were not fine repair,stone crusher that is refined, based on the grinding wheel grain trim on the more micro edge contour.

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