1、F-Z7-/7 however, most engine bearings have more internal clearance (to provide for expansion in the hot engine) than is advisable for use on a balancing machine. Moreover, a large supply of balancing machine support adapters would be required to accommodate the many engine bearing sizes in use. bear
2、ings may require very tight inner race fits; such fits are not necessary for slave bearings and thus risk of shaft damage can be avoided by use of slave bearings. 3.4 Eccentricity in all rolling element bearings constitutes a potentially significant error source for the balance of a rotor. engine be
3、aring and the slave bearing may have different eccentric: ties between the inner race and the bore and also different angular positions of these eccentricities. Thus, the axes of rotation in the balancing machine and engine assembly may not coincide. This in turn may cause a substantial residual unb
4、alance in the engine assembly. If the inner race eccentricities of both the slave bearing and the engine bearing have the same angular positions, the unbalance of a perfectly balanced rotor is the result of the difference in eccentricities of the slave bearing and the engine bearing rather than the
5、eccentricity of the engine bearing alone. Also, some engine For instance, the 4. APPLICABLE DOCUMENT: SAE ARP 587 - Balancing Equipment for Jet Engine Components, Compressor and Turbine-Rotating Type For Measuring Unbalance in One or More Than One Transverse Planes 5. REQUIREMENTS: 5.1 Workmanship:
6、In general, material quality, heat treating procedure, forging, machining, hand1 ing and preparation for shipping chal 1 be equivalent to commercially processed bearings suppl ied for the aircraft gas turbine industry. 5.2 Materials: 5.2.1 Materials shall conform to customary industry standards for
7、high precision aircraft quality bearings and should be subjected to testing and controls applicable t9 equivalent bearings of conventional sizes. 5.2.2 The metal used for balls and rings should be homogeneous in structure, free from pipes, seams, laminations, excessive inclusion of nonmetal1 ic impu
8、rities and such other internal defects as would render the material unsuitable for the intended purpose. 5.2.3 Hardness: BALLS RC58-62 or equivalent RACES RC58-62 or equivalent The hardness should be higher in roll ing elements. SAE ARP*1202A 87 8357340 O025244 5 W Page 3 -G3 I ARP 1202A 5.3 Dimensi
9、ons and Tolerances: 5.3.1 Dimensions and tolerances shall be equivalent to ABEC-7 except as shown in Tables I and II herein. 5.3.2 Outer ring dimensions shall conforin to specifications shown in Table II which covers the range of sizes generally used with machine types described in ARP 587. finish,
10、size and tolerance are to be specified by user. 5.3.3 Inner ring range of sizes shall conform to Table II, but final bore 5.3.4 Bearing width shall conform to Table II. 5.3.5 Ball dimensions or other internal features of bearings not covered by ABEC-7 or Tables I and II herein shall follow design pr
11、actice appropriate for comparable bearings supplied to the aircraft gas turbine industry. PREPARED BY SAE COMMITTEE EG-I, AEROSPACE PROPULSION SYSTEMS SUPPORT ECU1 PMENT SPONSORS: BRUCE SHULL AND EMIL WISEKAL, EGI-A ,- ._ - - SAE ARPmL202A 87 W 8357340 0025245 7 M I ARP 1202A ma Page 4 -o TABLE I -
12、General SPecifications (inches) Radial Play 0.0014 - 0.0019 Maximum Runout Ou ter Race 0.001 F.I.R. Maximum Runout Inn er Race 0.0001 F. I.R. 6,500 O.D. except balls made of material shall be heat stabilized at 400F (204OC). 1 material AIS1 52100 Bearings shall be made Conrad type construction havin
13、g deep grooves with uninterrupted raceways. Slave bearing runout introduces a balance error of 0.5 (Runout F.I.R.) X (rotor mass). slave bearing runout may have to be reduced. If the error exceeds the specified balance tolerance, the TABLE II - Standard Dimensions (inches) Nom i na1 Outs i de Diamet
14、er Bear i ng Number Inn er Ra ce Bore Range Nominal Width 4.1 250 2.3611 - 2.7999 O .6875 1 2 5.6250 2.8000 - 3.9599 3,9600 - 4.6999 O ,875 O .875 6,5000 3 4 8.7500 4.7000 - 5.8999 1.125 1.125 4A 5 5 .go00 - 6.5000 8.75000 10.7500 6.5000 - 8.0000 . 1.375 2,000 8.0000 - 9.5000 6 7 13.000 15 .o000 * 2.000 9,3000 - 10.8749
