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Main shaft of the lathe and revolving stage use the rational exertion of the bearing


28th February 2010 Bearing Technology 0 Comments

Rational exertion of the main shaft bearing

The bearing precision used in main shaft of the lathe should be ISO P5 or the above P5 or P4 is the precision grade of ISO, it is usually P0, P6, P5, P4, P2 from low to high ,And support to the main shaft of high-speed, high precision machine tools such as the numerical control lathe, machining center,etc., need, select ISO P4 or precision of the above for use. Main shaft bearing including horn contact ball bearing, taper roll sub bearing, and cylinder get away types such as the sub bearing,etc..

1. The accurate angle contacts the ball bearing

In several kinds of above-mentioned bearings, are exposed to the ball bearing Fig. 1 with the accurate angle Use most extensive. Horn contact to it rolls body to be ball ball bearing, because it whether one order, contact ,So can offer higher rotational speed, smaller caloric value and higher rotatory precision. Employ the occasion in some ultrafast main shafts, will adopt the ceramic ball generally Si3N4 or Al2O3 Hybrid bearing. Compared with traditional quenching the steel ball completely completely, the characteristic of the ceramic ball material has high rigidity, high rotational speed, high temperature resistant, longe-lived characteristic for the ceramic ball bearing, thus satisfy advanced customer’s demands for lathe bearing products.

The accurate angle contacts the ball bearing

In case of that the angle is exposed to the contact angle of the ball bearing, it is the contact angle of 15 and 25 that relatively prevail at present; Usually the contact angle of 15 has higher performance of rotational speed, and the contact angle of 25 has higher axial bearing capacity. Because the choice of year is exposed to the influence that the ball bearing employs on the accurate angle very big in advance, in high to bear the weight of, high occasion of rigidity, generally will select medium-sized or heavy-duty year in advance of bearing for use; And direct against some high rotational speed, high-accuracy application occasion, in the selecting type in early days of the bearing, need to pay attention to choosing the appropriate year in advance. Generally divided into light, medium-sized, heavy-duty three kinds in year in advance, it is more common in year in advance to be generally light. Use of customer, several big the intersection of bearing and manufacturer in the world offer in advance grinding the terminal surface of bearing generally at present but bearing with year in advance for convenience, that is to say usually said and omnipotent to mate people accurate corner keep in touch the ball bearing form. This kind of bearing dispenses with the regulating in year in advance of the customer, thus saved the time of installing.

2. Accurate taper get away sub bearing

In some heavily loaded lathes with certain requirement employ the occasion, if car silk machine, heavy-duty lathe and milling machine which neglects rubing, petroleum pipeline of the forging,etc., choosing the accurate taper to roll, the sub bearing is a kind of more ideal scheme. Because taper roll sub bearing roll son design that line contact, so it can offer very high rigidity for main shaft and bear the weight of; In addition, the sub bearing is that a kind of pure bearing that rolls is designed that the taper rolls, it can well reduce the bearing and operate the torsion and generate heat, thus guarantee rotational speed and precision of the main shaft. Because taper roll sub bearing can regulate year in advance axially in installation ‘ Backlash ,This can let customers optimize the backlash of the bearing to regulate better during the whole life cycle of the bearing.

In addition, block on some inner circles in the linear velocity is greater than the high-speed application of 30m/s, some tapers designed specially roll the sub bearing can meet the demands, if the intersection of TSMA and bearing or Hydra-Rib hydraulic float and block the side bearing ‘ Fig. 2 . The blocking of TSMA bearing has the lubricating oil holes of a plurality of axial directions, can adopt and circulate the oil is lubricated or the oil fog is lubricated, last son with blocking while can have oil distributed toing centrifugal force by keeping in touch area,thus can bearings lubricated fully, improve the bearing rotational speed. And Hydra-Rib hydraulic floats and blocks it is designed in year in advance for optimizing the main shaft system that the bearing is, have being can floating bearing block, with rolling there aren’t main aspects sub, can’t have inner circles fixed who block than common bearing; It if you can’t is it floating to and it’s time, block by side from ” The pressure ” System make a reservation, in this way can guarantee bearing can give play to the most excellent performance under each operating mode terms, and already used in the Chinese customer successfully.

Take hydraulic float, block and main shaft of bearing design

Roll as to taper sub precision of bearing choose but speech, bearing of ISO P5 grade apply traditional lathe to mainly and in the milling machine; If machining center, grinding machine application, usually can choose ISO P4 or accurate bearing of the above. In the main shaft design, more common taper rolls there are two kinds of sub bearing overall arrangements. First front and adopt one taper get away sub bearing respectively while being back, and adopt the face-to-face installation way, this kind of design is compact, rigidity is high and easy to install and regulating.

Second to adopt two taper roll sub bearing install the front as main shaft face-to-face, and the back bearing TDO which use outer lanes, two form inner circles Serve as floating end; Because of having floating ability, this kind of design can well bear the axial thermal expansion of the main shaft, and rigidity is very high, have guaranteed the precision of the lathe.

3. Accurate cylinder get away sub bearing

In the application of the main shaft of the lathe, pair lists accurate cylinder and rolls the sub bearing will be used to too, usually contact the ball bearing or thrust bearing and make application up with the accurate angle. This kind of bearing can bear larger radial load and allow higher rotational speed. Two in the bearing roll son arrange by way of crossing, fluctuate frequency than the intersection of uniline and the intersection of bearing and rise by a wide margin rotate, the amplitude is reduced by 60%- 70%. This kind of bearing usually has two kinds of forms: NN30, NN30K, two serial bearing inner circle tapes, block, the outer lane can be separated; NNU49, NNU49K, two serial bearing outer lane tapes, block, the inner circle can be separated, among them NN30K and NNU49K series inner circle are holes of awls conical degree 1:12 ,Cooperate with cone-shaped journal of the main shaft, move the inner circle axially and can make the inner circle swell, the intersection of bearing and backlash can it reduces to be even urgent bearing in advance in this way ‘ Shoulder the backlash state . The cylinder hole bearing usually adopts heat to hold, utilize and have a surplus of and cooperate to reduce the backlash of the bearing, or the tight bearing in advance. The NNU49 series bearing that can separate for the inner circle, generally roll correctly a finish machining more after the inner circle is loaded onto the main shaft, in order to improve the main shaft to rotate the precision.

Selecting type rationally of the bearing of the revolving stage

The commonly used gyration working bench has working benches of graduation and numerical control that turn the working bench round in the numerical control lathe. The numerical control lathe when processing some parts, except need the straight line of X, Y, Z three coordinate axes to enter to sports, sometimes also need the circular motion which winds X, Y, Z three coordinate axes, is called A, B, C axle separately.

It is can be used for realizing the circumference enters to sports, in addition turning the working bench round in numerical control, can also finish graduation sports. And the function of the working bench of graduation just transfers the work piece to the location to change the surface, cooperate with using with changing one one hundred sheets of devices automatically, realizing installation of work piece can finish many kinds of processes of several Taxies, so, have raised working efficiency greatly. Working bench of appearance and graduation of the numerical control revolving stage has few differences, but have a series of characteristics on the structure. Because the numerical control revolving stage can be realized and entered to sports, it gives with the entering of numerical control lathe on the structure and drives the organization to have much in common. The ones that drove the organization to realize in difference were entered to sports by straight line, and what the numerical control revolving stage is realized is that the circumference enters to sports.

Turn the working bench round and is widely used various numerical control milling machine, boring machine, various the lathe of setting up the car and setting up milling etc.. Besides demand, turn working bench round, can bear the intersection of work piece and weight well, need, guarantee it in gyration precision under of bearing the weight of. The bearing of the revolving stage, as the key part of the revolving stage, while the revolving stage runs, not only want, have very high bearing capacity, need, possess high to turn precision round, not high to resist, topple ability, and higher the intersection of rotational speed and ability,etc..

1. Thrust ball bearing cylinder get away sub bearing

The thrust ball bearing can bear certain axial force, so this bearing is used mainly for bearing the weight of the work piece; And cylinder roll sub bearing use mainly for the localization of the radial and bear external the intersection of radial and force ‘ For example cut strength, mill and pare strength etc. . This kind of design is employed extensively, and the cost stands opposite each other cheaper. Because thrust ball whether one order bearing that contact, so it bear the weight of force to be relatively relatively more limited axially, used mainly in the small-scale or medium-sized lathe and turn the working bench round. In addition the lubrication of thrust ball is more difficult.

2. Quiet to press bearing accurate cylinder get away sub bearing

Quiet to it presses bearings to be whether one supply pressure with oil by outside, set up quiet to press, bear the weight of the oil film by realizing the sliding bearing that the liquid lubricates in bearing. The liquid is quiet to press the bearing and work from starting to stop lubricating in the liquid all the time, unworn has long performance life, it is small to start the power; In addition the bearing have, rotate precision to be high also, oil film rigidity large, can inhibit the intersection of oil film and the intersection of person who shake and advantage from. The accurate cylinder has rolled the sub bearing has very good radials that bears the weight of strength, and because has adopted the accurate bearing of grade, the gyration precision of turning round working bench can get the assurance too. The gyration working bench which uses this kind of design can bear very high axial force, the weight of some work pieces exceeds above 200t, the revolving stage diameter exceeds 10m. But the design have some weak point too, must attach, come, supply pressure oil by one specialized oil supply system while being quiet to press bearing, it is more complicated to safeguard, and the cost is higher.

3. Sub bearing of the roller alternately

Get away sub bearing alternately ‘ Fig. 3 The application on the revolving stage is more general. Roll alternately sub characteristic of bearing to have two roll line in the bearing, whom two platoon arrange alternately get away son. Compared with the situation that the traditional thrust bearing radial centers the bearing to make up ‘ Fig. 4 ,Roll compact sub bearing alternately and volume small and exquisite, and simplified the working design of platform, thus has reduced the cost of the revolving stage.

In addition, because of using the tight strength in advance that is optimized, this kind of bearing has very high rigidity, therefore rigidity and precision of the revolving stage have got the assurance. Benefit from two roll design of son alternately, the effective span of the bearing can be improved notably, so this kind of bearing has very high resisting and toppling the moment. Roll alternately in the sub bearing, divided into two kinds of types again: First roll sub bearing alternately cylinder, second get away sub bearing alternately taper. Usually, the sub bearing is low that the sub bearing price roll more alternately than tapers that cylinders roll alternately, in suitable for the rotational speed relatively lower revolving stage is employed; And taper roll alternately sub bearing adopt taper roll son purely rolling to design, operate the precision high, the ability of rotational speed is strong, have reduced advantages such as axle length and process cost,etc.. The sub bearing is suitable for all kinds of vertical or horizontal boring machines to roll alternately, and set up and rub, set up application of car and large-scale gear milling machine,etc..

In a word, the bearing, as lathe main shaft and key part of the revolving stage, the operation of the lathe behaves and plays a very important role. In order to choose suitable size and bearing of the type, we need to consider various operating mode conditions synthetically, for example running speed, lubricating, installing the type, main shaft rigidity, precision,etc. is required. In terms of the bearing, only fully understand its design characteristic and advantage and disadvantage brought from this, could give play to the best performance of the bearing.










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