JB/T 5389.1-1995 Rolling bearings Four-row cylindrical roller bearings for rolling mills JB/T5389.1-1995 Standard download and decompression password: www.bzxz.net
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JB/T5389.1---1995 Foreword This standard is formed by merging the two standards JB4039--85 "Outline Dimensions of Four-row Cylindrical Roller Bearings for Rolling Mills" and JB/T5389-91 "Technical Conditions of Four-row Cylindrical Roller Bearings for Rolling Mills". The main revisions are: a) Improve the code method of four-row cylindrical roller bearings; b) Add some bearing models: c) Remove the words "Inner diameter is a non-preferred size"; Radial clearance", inner diameter size 500mm or more, the clearance value is the same as that of foreign advanced bearings d) The clearance value is the same as GB4604-93 "Product Sample of Rolling Bearing Company"; e) The technical requirements for the inner ring of commercial bearings are moved to the appendix; f) The tapered hole clearance value in the original standard appendix is ??cancelled. Appendix A of this standard is the standard appendix. Appendix B of this standard is the prompt appendix. This standard is proposed by the National Technical Committee for Standardization of Rolling Bearings. This standard is under the jurisdiction of the Luoyang Bearing Research Institute of the Ministry of Machinery Industry. The drafting units of this standard are: Wafangdian Bearing Factory and Beijing Bearing Research Institute. The main drafters of this standard are: Zou Renkai and Li Lianyuan. 195 1 Scope Standards of the Machinery Industry of the People's Republic of China Rolling Bearings Four-row Cylindrical Roller Bearings for Rolling Mills JB/T5389.1:1995 This standard specifies the structure, code, size and technical conditions of four-row cylindrical roller bearings for rolling mills (hereinafter referred to as bearings). This standard applies to the manufacture, inspection, design selection and acceptance of bearings. 2 Referenced Standards The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T272--93 Rolling bearing code method GB307.284 Rolling bearing tolerance measurement method GB307.3--84 Rolling bearing GB 3203--82 G13 7811 ---87 JB 1255..91 --General technical requirements Technical conditions for carburizing bearing steel Rolling bearing parameter symbols Technical conditions for heat treatment of high carbon chromium bearing steel rolling bearing parts J3/T 2974 ---93 JB/T 3016.-.91 JB/T 3017- [B/ 3034 -91 93 JB/T 3573---93 JB/T 3574--92 ZBJ11020 ·89 Z13 J36 001 --86 ZB J36 002—86 3 Symbols and abbreviations Rolling bearings Rolling bearings Rolling bearings Rolling bearings Rolling bearings Rolling bearings Supplementary provisions for code methods Technical conditions for packaging nailboard boxes Technical conditions for packaging cartons Oil seal anti-rust packaging Measurement and evaluation methods of radial clearance Product marking Inspection rules for rolling bearings and their commercial parts Quality standard for carburizing heat treatment of rolling bearing parts Quality standard for deep carburizing heat treatment of rolling bearing parts Except for the following symbols, the symbols cited in this standard conform to the provisions of GB7811. Factory: Inner ring nominal chamfer \: Outer ring nominal chamfer mia: Inner ring minimum single chamfer size ixain: Outer ring minimum one-way chamfer size dimpnaxd2npmnin: Between the two inner rings of the bearing, the maximum average inner diameter and the minimum average inner diameter di: Inner ring raceway nominal diameter : Inner ring raceway diameter deviation Approved by the Ministry of Machinery Industry on 1995-06-16 496 Implemented on 1996-07-01 JB/T 5389.1 Single.-Radial plane. Inner ring raceway diameter variation E: Inner ring raceway nominal width Li: Inner ring raceway straightness diau—dimp: Difference between the average diameters at both ends of the inner ring raceway Sa: Variation of the inclination of the inner ring raceway element line to the base end face Fw: Inner diameter of roller group 4Structural type FC type FCD type- Four-row cylindrical roller bearing (see Figure 1): One pair of inner rings and four-row cylindrical roller bearings (see Figure 2): FCDP type 1995 Double inner ring four-row cylindrical roller bearing with flat retaining ring on the outer ring (see Figure 3). Figure 1 FC type Figure FCIP type Figure 2 FCD type 497 5 Code 5.1 Code composition JB/T5389.1---1995 The bearing code consists of type code, scale code and post-code, and the arrangement order is as follows; post-code Scale code Type code 5.2 Type code The type code consists of uppercase Latin letters, indicating the structural characteristics of the bearing, see Table 1. There is a half-character space between the type code and the size code (except for the code with \): Table] Type code FC FCD FCDP Size code 5.3 Conclusion Four-row cylindrical liquid bearing (one inner ring)Double inner ring four-row cylindrical roller bearing Features Double inner ring net-row cylindrical roller bearing with flat retaining ring on the outer ringFeatures Size codes are composed of Arabic numerals, which represent the codes of nominal inner diameter N, nominal outer diameter D and the number of millimeters of nominal width 阝 from left to right. The representation method is shown in Table 2. Table 2 Code Item Table Method 5.4 Post-code Nominal inner diameter code Nominal inner diameter in millimeters/5 Nominal outer diameter D code Nominal outer diameter in millimeters/5 Nominal width B code Nominal width in millimeters Post-code is a supplementary code for bearings when the internal structure changes and for indicating tolerance grade, clearance, heat treatment, etc. Post-codes are represented by uppercase Latin letters (or Arabic numerals). The rules for compiling post-codes shall comply with the provisions of GB/T272. The meaning and arrangement order are shown in Table 3. Table 3 Sequence number 3 5.5 Marking example Rolling bearing 498 Item name Internal structure Cage and material Tolerance grade Travel Chen Others FCD100144530/P53 Contains Changes in bearing internal structure Meaning Changes in bearing cage structure and material Tolerance grade specified in the standard Clearance group specified in the standard Heat treatment, lubrication, etc. JB/T 5389. ---1995 Hip code A, B or C According to JB/T2974 According to GB/T272 According to GB/T272 According to JB/T2974 FCD 100 144 530/F53 B/T5389.1--1995 Tolerance Grade 5. Radial runner 3 Correction 1 Nominal width is 530mm - Nominal outer diameter is 720mm - Nominal inner diameter is 500mm "Double inner four-row round rolling bearing 5.6 For bearings whose dimensions are not specified in this standard, the type code and size code in the code are separated by "/\". Example: FC/4258192 bearing has an outer diameter of 290mm and a width of 192mm, which is not specified in this standard. FC/82120440 bearing has an inner diameter of 410mm, which is not specified in this standard. 6 Dimensions 6.1 FC type bearing dimensions shall be in accordance with the provisions of Table 4. Table 4 Bearing code FC:182870 FC2028104 FC202970 FC2030106 FC2234120 FC2436105 FC2640125 FC 2842125 FC2842155 FC2942155 FC2945156 FC3045120 FC3046156 FC3248168 FC3248124 FC:3450170 FC3452120 FC 3652168 FC3656180 FC3852168 FC3854200 FC:3856200 FC4056200 FC4058192 FC4064216 FC1260210 d 90 100 100 100 110 120| |tt||130 140 140 145 145 150 150 160||tt ||160 170 170 180 180 190 190 190 200 200 200 210 D 140 140 145 150| |tt||170 180 200 210 210 210 225 225||tt ||230 240 240 250 260 260 280 260 270 280 280 290 320 300 B 70 104| |tt||70 106 120 105 125 125 155 155||tt ||156 120 156 168 124 170 120 168 180 168 200 200 200 192 216 210 Fu| |tt||105 111 113 113 127 135 14.9 158||tt ||158 166 169 168 174 183 183 192 195 202 207 212 212 214 222 226 233| |tt||231 r. 1.5 1. 5 1. 5 1.5 2 2 2 2 2 2 2| |tt||2.1 2.1 2.1 2.1 2.1 2.1 2.1 2. 1 2.1 2.1 2.1 2. 1||h||2.1||h||mm||hh||1. 1 1. 1 . 1.1 51 2 2.1 2.1 2.1 22, 1 .1 2.1 2、1 2.1 2. 2.1 2.|| tt||2.1 2. ay 小明代号 FC4462192 FC:4464210 FC 4666206 FC:4668260 FC:4866220 FC 4872220 FC 5070220 FC 5274220 FC5276280 FC:5476230||tt| |FC:5678220 FC 5681280 FC 5882240 FC 5881300 FC 6084218 FC 6084240 FC6490240 FC:6196290 FC 6692340 FC: 6892260 FC:6896280 d 220 220 230 230 240 240 250 260 260 270 280|| tt||280 290 2903 300 300 320 320 330||tt| |340 340 JB/T 5389.1-—1995 裴4(完) n 310 320|| tt||330 340 33) 360 350 370 380 380||tt ||390 420 410 420 120 420 150 480 460 460 480 B 192 210 206 260 220| |tt||220 220) 220 280 230 220 280 240|| tt||300 2.18 240 240 290 340 260 280||tt| |2FCI型、FCDP型图像发动发动在按表5的设计。6.2 表5 长谦 代号 FCD型 FCD 6084300 FCD6496350 FCD 6692340|| tt||FCID6896350 FCD 72102370 FCD 72104380 FCD74104380 FCD 76108400 FCD 80112410 FCD 84120440 FCD 88124450 FCD 92130-170 FCD 96136500 FC 96130450 500 FCDP型 FCDP 6084300 FCDP 6496350 FCDP 6692340 FCDP 6896350 FCDP 72102370 FCDP 72104380 FCDP 74104380 FCDP 76108400 FCDP 80112410 FCDP 84120440 FCDP 88124450 FCDP 92130470 FCDF 96136500 FCDP 96130450 & 300|| tt||320 330 340 360 360 370 380 400||tt| |420 440 460 480 480 420 480 460 480 510 520 520 540 560 600 620 650|| tt||680 650 F 246 248 260 261 264||tt| |272 278 292 294 298 312 318 320 327 332 332 355 364 365 370 374 300|| tt||350 340 350 370 380 380 400 410||tt| |170 450 470 500 450 F 'min 2.1bZxz.net 2.1 2.1 2.1 2.1 2.1 3 3 3 3| |tt||3 4 4 4 4 -1 4 4|| tt||4 332 364 365 378 392 405 409||tt| |422 445 170 487 509 532 525 raai 3 4 1 4 1 4 5 5 5|| hh||行||hh||mm||hh||2. 1 2.1 2.1 2.1 2.1 2.1 3 3 3| |hh||3||hh||3||hh||4||hh||4||hh||4||hh||4||hh||4||hh||mm||hh ||3 4 4 4 5 5 5 5 6 FCI型 承 代号 长 FCDP型 FCD 100144530 FCD) 106156570|| tt||FCD 110148510 FCD 112164630 FCD 114163594 FCD 120164575 FCD 120174640 FCD 126180670 FCD 130184670||tt ||FCD 134190700 FCD 138196715 FCD 140186620 FCD 142200715 FCD 146192620 FCD 150200670 FCD 160216700||tt ||FCD 160230850 FCD170230840 FCD180244840 FCD 1902721000 FCD 200272800 FCD 2123001120 FCD 222296980 FCD 2243161150. |tt||FCIDP 114163594 FCDP 120164575 JB/T5389.1---1995 表5(完) 500 530 550 560 570 600. FCDP146192620 FCDP 150200670 FCDP 160216700 FCDP 160230850 FCDP170230840 FCDP 180214840 FCDP 1902721000||tt ||FCDP 200272800 FCDP 2123001120 FCDP 222296980 FCDP 2243161150 600 630 650 670| |tt||690 700 710 730 750 800 800 850||tt 1110 6和5级安全公差应果公公差电影视频表6、表7的设计720 780 740 820 815 820| |tt||870 900 920 950 980 930 1000 960||tt ||1000 1080 1150 1150 1220 1360 1360 1500 1480. |80 120 180 到 主内场 120 180 250 250315. -18 30 22 Va, 6 5 Vamy 公 6 915 15 1325 18 1530 23 3525|| tt||18 35125 12 14 19 23 26 11 14||tt ||17 19 差 5 max 25 5 7 8 Kia 等 13 30 18 4020 50 25| |tt||R 530 570 510 630 59.1 575 640||tt ||670 670 700 715 620 715 620 670 700 850 840 840 1000 800 1120 980 1150| |tt||d iunpmnx F 568 601 600 625 628 660|| tt||682 698 723 756 767.5 763 787.5 790||tt| |813 878 905 928 989 1058 1084 1165 1210 1240 el anigmin 级 5 8 10! 8 18 E Trmua 6 6 6 6 6 6|| tt||6 7.5 7.5 7.5 7.5 7. 5 7.5 7.5 7.5 7.5 *7.5 7.5 7.5 7.5 9.5 9.5 9.5 A 0.6.5 可下于室 200||tt| |m 6 6 G 6 G G 7.5 7.5 7.5 7.5 7.5 7.5 7. 5 7.3 7.5 7.5 7.5 7.5 7.5 9.5 9.5| |tt||9.5 five max 25 25030 300 30 30||tt ||3501 35 : : 19 501 /mm ?????? 315 0.6.5 上自定 400 400500 630 500 630 1800 800| |tt||1000 1000125 D/mm ?????? 80 120 150 180| |tt||250 315 400 500 630 到 120 150||tt ||门 门 下自电 40-30/--23/40 45 5040 75|| tt||—1004 125 lo.6.5 上内家 C 0 180 250 315 400 500 630 800 80011000 1000 1250|| tt||7.2 1250 1600 游隙 0 0 0 0 0 45 3050 75 100 125 61 下自定 15| |tt||18 25 30 25 40 -45 50 75|| tt||20 25 28 33 38 45-- 31 35|| tt||40 JB/T5389.1--1995 表 G(完) Vrip 公 差 max 3012312 34 27 Vnp 1015 19 1325 15| |tt||18 23 28 E 50 3575 -100 j—60 125 -160 15 18 20 5 2.8 34 38 1 40100 125 38 10 12 13 16|| tt||26114 30 Kia 等 级 5 30 115||tt| |60 65 1570 80 90 1100 表了 外圈||tt| |Vne 公 11 14 19 23 26 1830 20 34 38 h 60:3575 160] 图像达向游隙按表8的设计。| |tt||1 14 15 19 21 25 29 34||tt ||差 10 18 20 Dirarmax Dzrapmir 等 ct npinax -||tt ||d ap [20115[12 23 18 2520115 38 50 63| |tt||K. 级 0 6 5101 max 35 9|| tt||7 8 9 10 12 18 45 20||tt| |E13 15 9 1o 18 113 2014 2317 2519 8 9 10 12 14 40 45 18|| tt||20 23 5025 60 30 r 9.6.5 正偏卷下偏券 400 40 m 5 miax 15 450150 500160 tt||10 11 13 15 18 120 70 135||tt| |8040 100/50 23 25 3823 18 [12016030 50||tt ||30 63 80 20 140 75 1 30 160 190 表8四列圆柱死子开发很向游隙(圆柱孔)公称内称||hh||d/mm||hh||性事||hh||80||hh||100||hh||120||hh||502| |tt||到 100 120 140 2组 min 15 15|| tt||15 max 50 55 60 min 50 50||tt| |60 0 max 85 90 105 nin 75 3维 85 1oo max 110 125 145 min 105| |tt||125 4组 净 门 心 0 miax 140|| tt||165 145 190 200 250 -250 17 45||tt ||50120 aim 0.65 max 8 同 axes 300 -350 8 8 10 内 11 13 400 的 150 500|| tt||750 et 15 相 18 同20 -1000 1250|| tt||-1600 5组 in 155 180 200 25 μm|| tt||max 19元 220 245 公称内称 d/mtm 性交 140 160 180 200 225 250 280 315 355| |tt||400 450 500 560 630 710 800 900||tt ||1000 1120 1250 160 180 200 225 250 281) 315 355 400 150 500 560 630 710 800 900 1000 1120 1250 1400 2组 min| |tt||20 25 35 4.5 45 55 55 65||tt ||100 110 110 120 140 145 150 180 200 220 230 270 max 70 75 90 105| |tt||110 125 130 145 190 210 220 240||tt ||260 285 310 350 390 430 470 530 JB/T 5389.1--1995 表8(完) 组 mit 70 75 90||tt ||105 110 125 130 145 190 210 220 240 260 285 310 350 390 430 170 530| |tt||max 120 125 145 165 175 195 205||tt ||225 280 310 330 360 380 425 470 520 580 640 710 790 min 115 3组 120 1:453 160 170 190 20 225 280 310 330 360 380 425 470 520 580 G40|| tt||710 790 mtx 165 170 195 220 235||tt| |260 275 305 370 410 .140 480 500 565 630 690 770 850 950 1050 min 165| |tt||170 4组 max 215 220 195 220 235|| tt||260 275 305 370 110 440 480 500||tt| |565 630 690 770 850 950 1050 250 280 300 330 350 385 460 510 550 600|| tt||620 705 790 860 960 1060 1190 1310||tt| |min 225 250 275 305 330 370 410 5 155 510 565 625 max 275 300 330)| |tt||365 393 440 435 535 600 665 735||tt ||7.3 Materials/热方法 7.3.1 高频黎黎黄钢钢面的黄院的黑色,应电汉下载手机电视,读选用ZGCr15.ZGCt15SiMn、vacuum脱气GCr15.GCr15SiMn及--般GCr15、GCr15SiMn Bearing steel.7.3.2 Bearing parts made of high-carbon chrome bearing steel G20Cr2Ni4A and G20Cr2Ni4 etc., whose raw materials should meet the requirements of FB3203. 7.3.3 Bearing parts made of high-carbon chrome bearing steel, whose heat treatment quality should meet the requirements of JB1255. 7.3.4 Bearing parts made of carbon steel bearing, heat treatment quality according to the depth of carbon layer depth shall meet the requirements of 73J36001 or ZB「36002. Manufactured bearing parts should be handled with high precision, their hardness should meet the requirements of JB1255. 7.4 Bearing parts must be handled with care. The surface doesn't have a texture. 12 regulations. 6 2 regulations. 6 1--1995 表8(完) 组 mit 70 75 90 105 110 125 130 145 190 210 220 240|| tt||260 285 310 350 390 430 170 530||tt| |max 120 125 145 165 175 195 205 225 280 310 330 360 380 425 470 520|| tt||580 640 710 790 min 115 3组 120||tt ||1:453 160 170 190 20 225 280 310||tt ||330 360 380 425 470 520 580 G40 710 790 mtx 165 170 195 220 235 260| |tt||275 305 370 410 .140 480 500 565|| tt||630 690 770 850 950 1050 min 165||tt| |170 4组 max 215 220 195 220 235 260 275 305 370 110 440 480 500 565| |tt||630 690 770 850 950 1050 250 280||tt ||300 330 350 385 460 510 550 600 620 705 790 860 960 1060 1190 1310 min| |tt||225 250 275 305 330 370 410 5||tt ||155 510 565 625 max 275 300 330)||tt| |365 393 440 435 535 600 665 735 7.3 Materials and heat treatment 7.3.1 High carbon chromium bearing steel manufactured bearing parts, according to different usage requirements, separately selected ZGCr15.ZGCt15SiMn、vacuum脱气GCr15.GCr15SiMn---般GCr15、GCr15SiMn bearing steel。 7.3.2 Bearing parts made of high-carbon chrome bearing steel G20Cr2Ni4A and G20Cr2Ni4 etc., whose raw materials should meet the requirements of FB3203. Bearing parts made of carbon steel, whose heat treatment quality is based on the depth of the carbon layer should meet the requirements of 73J36001 or ZB「36002. 7.3.5 Bearings made of high-carbon chrome steel电影应可通高回火电影,其图度应可以下载JB1255的实施。 7.4 Bearings的滚子素线must have 呈得度或修形得度。 7.5 Bearings件不可有裂纹。 工作电视不成学烧生、自点和脱確。7.6本未未计算长国,应电影电影图样受机行电影。8 明是核性和脱行系统 8.1 公差的电影时间按GB307.2的设计。6 1--1995 表8(完) 组 mit 70 75 90 105 110 125 130 145 190 210 220 240|| tt||260 285 310 350 390 430 170 530||tt| |max 120 125 145 165 175 195 205 225 280 310 330 360 380 425 470 520|| tt||580 640 710 790 min 115 3组 120||tt ||1:453 160 170 190 20 225 280 310||tt ||330 360 380 425 470 520 580 G40 710 790 mtx 165 170 195 220 235 260| |tt||275 305 370 410 .140 480 500 565|| tt||630 690 770 850 950 1050 min 165||tt| |170 4组 max 215 220 195 220 235 260 275 305 370 110 440 480 500 565| |tt||630 690 770 850 950 1050 250 280||tt ||300 330 350 385 460 510 550 600 620 705 790 860 960 1060 1190 1310 min| |tt||225 250 275 305 330 370 410 5||tt ||155 510 565 625 max 275 300 330)||tt| |365 393 440 435 535 600 665 735 7.3 Materials and heat treatment 7.3.1 High carbon chromium bearing steel manufactured bearing parts, according to different usage requirements, separately selected ZGCr15.ZGCt15SiMn、vacuum脱气GCr15.GCr15SiMn---般GCr15、GCr15SiMn bearing steel。 7.3.2 Bearing parts made of high-carbon chrome bearing steel G20Cr2Ni4A and G20Cr2Ni4 etc., whose raw materials should meet the requirements of FB3203. Bearing parts made of carbon steel, whose heat treatment quality is based on the depth of the carbon layer should meet the requirements of 73J36001 or ZB「36002. 7.3.5 Bearings made of high-carbon chrome steel电影应可通高回火红设度,其图像应可以下载JB1255的实施。 7.4 Bearings的滚子素线must have 呈得度或修形得度。 7.5 Bearings件不是有裂纹。 工作电视不成存烧生、自点和脱確。7.6本未未计算长国,应电影电影图样受机行电影。8 明是核性和脱行系统 8.1 公差的时间方法按GB307.2的设计。6 140 480 500 565 630 690 770 850 950| |tt||1050 min 165 170 4 groups max 215 220|| tt||195 220 235 260 275 305 370 110||tt| |440 480 500 565 630 690 770 850 950 1050 250 280 300 330 350 385 460|| tt||510 550 600 620 705 790 860 960||tt| |1060 1190 1310 min 225 250 275 305 330 370 410 5 155 510 565 625 max|| tt||275 300 330) 365 393 440 435 535||tt ||600 665 735 7.3 Materials and heat treatment 7.3.1 Bearing parts made of high carbon chromium bearing steel should be treated separately according to different usage requirements. Choose ZGCr15.ZGCt15SiMn, vacuum degassed GCr15.GCr15SiMn and general GCr15, GCr15SiMn bearing steel. 7.3.2 The raw materials of bearing parts made of carburized bearing steel G20Cr2Ni4A and G20Cr2Ni4 should comply with the provisions of (FB3203). 7.3.3 The heat treatment quality of bearing parts made of high carbon chromium bearing steel should comply with the provisions of JB1255. 7.3.4 The heat treatment quality of bearing parts made of carburized bearing steel should comply with the requirements of 73J36001 or ZB "36002 according to the depth of the carburized layer. 7.3.5 When the bearing service temperature exceeds 120C, the bearings made of high carbon chromium bearing steel The parts should be highly tempered and their hardness should comply with the requirements of JB1255. 7.4 The roller line of the bearing must be convex or modified. 7.5 The working surface of the bearing is not allowed to have cracks. Burns, soft spots and decarburization. 7.6 Items not specified in this standard shall comply with product drawings and current standards. 8 Testing methods and inspection rules 8.1 Testing methods 8.1.1 Tolerances The measurement method is in accordance with GB307.2 6 140 480 500 565 630 690 770 850 950| |tt||1050 min 165 170 4 groups max 215 220|| tt||195 220 235 260 275 305 370 110||tt| |440 480 500 565 630 690 770 850 950 1050 250 280 300 330 350 385 460|| tt||510 550 600 620 705 790 860 960||tt| |1060 1190 1310 min 225 250 275 305 330 370 410 5 155 510 565 625 max|| tt||275 300 330) 365 393 440 435 535||tt ||600 665 735 7.3 Materials and heat treatment 7.3.1 Bearing parts made of high carbon chromium bearing steel should be treated separately according to different usage requirements. Choose ZGCr15.ZGCt15SiMn, vacuum degassed GCr15.GCr15SiMn and general GCr15, GCr15SiMn bearing steel. 7.3.2 The raw materials of bearing parts made of carburized bearing steel G20Cr2Ni4A and G20Cr2Ni4 should comply with the provisions of (FB3203). 7.3.3 The heat treatment quality of bearing parts made of high carbon chromium bearing steel should comply with the provisions of JB1255. 7.3.4 The heat treatment quality of bearing parts made of carburized bearing steel should comply with the requirements of 73J36001 or ZB "36002 according to the depth of the carburized layer. 7.3.5 When the bearing service temperature exceeds 120C, the bearings made of high carbon chromium bearing steel The parts should be highly tempered and their hardness should comply with the requirements of JB1255. 7.4 The roller line of the bearing must be convex or modified. 7.5 The working surface of the bearing is not allowed to have cracks. Burns, soft spots and decarburization. 7.6 Items not specified in this standard shall comply with product drawings and current standards. 8 Testing methods and inspection rules 8.1 Testing methods 8.1.1 Tolerances The measurement method is in accordance with GB307.2 6 Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.