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Grinding processing and high-speed grinding technology of the bearing ring

29th June 2013 Bearing Technology 0 Comments

In bearing production, process the amount of labour and account for 60% of the total amount of labour in grinding, the used grinding machine quantity accounts for about 60% of all metal cutting lathes too, the cost processed in grinding accounts for more than 15% of the cost of whole bearing. As to the high-accuracy bearing, these proportions processed in grinding are larger. In addition, it is most complicated in the whole processing course that grinding is processed, it is still the most insufficient link so far to its understanding. This complexity shows: Require more performance indexes, the precision is higher; It is more complicated to process shaping mechanism, factors influencing machining accuracy are numerous; It is difficult to process the on-line testing of the parameter. So, process as to grinding of one of the key processes in bearing production, how to adopt the innovative technology, new technology, by finishing the grinding course high-accuracily, with high efficiency, low-costly, it is a primary service processed in grinding.

High-speed grinding technology

Two major goals that high-speed grinding can realize the modern manufacturing technology and pursue raise product quality and efficiency. Practice has proved: If will grind the speed when being be brought up to 50- 60m/s by 35m/s, general production efficiency can be improved by 30%- 60%, raise about 0.7- 1 times to durable degree of the emery wheel, the work piece surface roughness parameter value is reduced by about 50%.

The general grinding speed reaches above 45m/s and is called high-speed grinding. Represented by ZYS- 811 all automatic bearing internal grinder that I developed in the eighties China, take the lead in employing high-speed grinding technology in Chinese bearing trade’s collar grinding is processed, forming a complete set succeeds in developing high rigidity, high rotational speed, high-power electric basic shaft and high-speed emery wheel. And high-speed grinding employ extensively already outside the China, and than with adopt high grinding extensively, the high durable superhard abrasive such as CBN of degree, the grinding speed of the emery wheel has already reached 80- 120m/s, even higher. For instance: Germany Mikrosa, centerless grinder of Japan KOYO Company, bearing internal grinder of Japan TOYO Company,etc., the grinding emery wheel linear velocity of outer surface reaches 120m/s, the grinding linear velocity of interior surface reaches 60m/s- 80m/s.

Increase the emery wheel, drive ‘ Transmit The power and improving the stiffness of the lathe of the system, it is to realize an important measure of high-speed grinding, and the basic shaft unit at a high speed is the most crucial part of the high-speed grinding machine among them. In high-speed grinding, the emery wheel also needs to guarantee to have good grinding characteristics besides should have sufficient intensity ing, could obtain and rub the result high. In addition, the cooling device realizes one of the high-speed grinding vital devices too.

CBN emery wheel grinding technology

The abrasive of cubic boron nitride is abbreviated as CBN abrasive, the emery wheel made by it is called CBN emery wheel, it mainly possesses the characteristics of the following: The hardness is high, the thermal conductivity is high, heat good stability, can bear 1300- 1500 ℃ high temperature. Serviceability high, abrade light, grinding than reachable 4000-10000, grinding than mean grinding course remove the intersection of work piece and the intersection of material and quantity the ratio of to abrasion quantity of emery wheel And the ordinary corundum emery wheel is only 50- 80. Grinding strength is little, grinding is hot and small, it is small to process the work piece stress, the ply stress of the table is thin or does not have. Auxiliary time ‘ Repair the emery wheel, change the emery wheel Reduce greatly.

To Chinese bearing trade, it is one kind of new process technologies that use CBN pays collar grinding and processes, application prospect is very broad, but need to research and solve the following technology: Manufacturing technology, repairment technology, specialized bearing grinding machine and grinding cooling fluid of CBN emery wheel,etc..

Because CBN emery wheel have processing characteristicking good, carry on the intersection of bearing ring and grinding go on, develop and apply production to already abroad with the intersection of CBN and emery wheel, and is called ” Produce a technical great revolution of processing ” . Since 1982, CBN emery wheel has already been employed in large batches in Japan, and grow at top speed.

The outer surface grinding emery wheel moves balancing technique automatically

As to the grinding of outer surface, because the emery wheel is larger and the anisotropic organizer body, the systematic center of the emery wheel always deviates from the centre of the basic shaft, must cause the vibration of emery wheel system and the whole lathe at the time of the high-speed rotation, life time of the direct influence lathe. In this case, grinding is difficult to reach high precision to process, it is apt to cause the surface of the work piece to produce and rub and shake the line, the waviness increases.

Install moving the balancing device automatically of mechanical or other ways directly on the lathe emery wheel, approach the equilibrium position the most directly fast after the starting up, autobalance comparatively improves and can omit the static balance of the emery wheel. This technical break-through has promoted the development of grinding technology, can at the same time maximal limit lengthen the emery wheel, repairs and spends adamas and main shaft bearing life-span, reduce the lathe to shake, keep the original precision of the lathe for a long time.

Dispel the technology of the grinding idle stroke of interior surface fast

In all bearings rub the processing unit, the level of the grinding machine of interior surface has meaning symbolized. This is mainly that a grinding aperture has limited size and corresponding systematic mechanism set parameter of the emery wheel, having limited the stiffness of the craft system fundamentally, its machining accuracy is expected relatively much at the same time. All these require us to enter deep studying to the technological process of grinding of interior surface, except that the cutting ability that maximum gives play to lathe and emery wheel limiting, it is the key to raising grinding efficiency to reduce the time of auxiliary grinding, because the idle stroke of grinding accounts for about 10% of time of whole grinding.

At present, employ the technology of the comparatively extensive fast elimination grinding idle stroke to have the following aspects outside China: The grinding technology of controlling force, the grinding technology of constant power, utilize initiative survey meter technology and measure electricity main shaft current technology.

CNC numerical control technology and exchanging servo technology

Exchange the alignment module of servomotor and PLC programmable controller, the servo amplifier can form the servo system while linking up, the servomotor has optical rotary encoders itself, feedbacking the signal that it outputs to the servo amplifier can form half a closed loop control system. In the high rotational speed 3000rpm And low speed operates and can all guarantee the location accuracy, can finish the fast hopping, hasten quickly, repair compensating, thick precise grinding while using the servo system, make the feed mechanism of the lathe simplified greatly, characteristic reliability is improved greatly.

Exchange the technology of speed regulation by frequency variation

The linear velocity of the emery wheel is reduced with the consumption of the emery wheel gradually in grinding, its linear velocity proportion about 3 begun and ended: 2. At present, has already adopted the grinding of high linear velocity in the field of grinding of the emery wheel, in order to raise grinding efficiency, guarantee the quality conformance of grinding, adopt the programmable controller computing function and calculate the radius of the emery wheel after repairing the emery wheel each time, and then calculate and keep the frequency converter of the permanent linear velocity of the emery wheel inputting the frequency, and convey to the AC-drive, thus guarantee the linear velocity of the emery wheel is constant.

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