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1. Ren hp nht (Unified Thread UN)1.1 Gii thiuRen Unified Thread ra i sau chin tranh th gii ln th hai nhm mc ch tiu chun ha v tng cng kh nng lp ln i vi mi ghp ren ca ba nc M, Canada v Anh cng nh khc phc mt s hn ch trong phng php gia cng ren.c tnh hnh hc, kch thc, cp chnh xc, dung sai v k hiu ren Unified Thread c qui nh ln u tin trong tiu chun ANSI/ASME B1.1:1949 ban hnh nm 1949. Sau nhiu ln sa i, b sung phin bn mi nht ca tiu chun ny l ANSI/ASME B1.1:2003.Hnh 1. Profile c bn ca ren Unified Thread1.2 Cc dng ren ca Unified threadUnified Coarse Thread UNCUNC l loi ren bc th c dng rng ri nht cho cc mi ghp c bn ko thp v yu cu tho lp nhanh trn cc loi vt liu c bn thp nh gang, thp t carbon, ng, nhm.Unified Fine Thread UNFUNF l loi ren bc mn, c dng cho nhng mi ghp yu cu bn cao hoc nhng mi ghp c thnh mng v khong lp ghp ngn. Ngoi ra, nh gc nng ren nh, ren UNF cn c trong nhng trng hp cn s vi chnh chiu di lm vic ca ren.Unified Extra Fine Thread UNEFUNEF l loi ren bc cc mn, c dng khi chiu dy mi ghp nh hn chiu dy mi ghp bng ren UNF.Ngoi ra, gim ng sut tp trung, y ca ba loi ren ny c bo trn v cho ra i dng ren UNR vi k hiu tng ng l UNRC/UNRF/UNREF. Bulong ca ba loi ren ny vn dng ai c UN.Constant Pitch Series UN SeriesDng ren bc khng i ny c dng khi cc dng ren UNC, UNF v UNEF khng p ng c cc yu cu k thut khi thit k. N bao gm 8 kiu vi s ren trn 1 inch ln lt l 4, 6, 8, 12, 16, 20 ,28 v 32Unified special UNSL s kt hp gia ng knh ren v s ren trn 1 inch ca kiu ren ny khng c trong nhng tiu chun k trn. Khng nn dng kiu ren ny tr khi c nhng yu cu khc khe v mt k thut trong thit k.

Bng 1. Phi hp gia ng knh ren v s vng ren trn 1 inch ca ren UN & UNR (trch tiu chun ASME B1.1-2003)1.3 Dung sai renTiu chun ANSI/ASME B1.1:2003 phn ra 3 cp dung sai (1, 2, 3) nh gi chnh xc ca ren v hnh hc, v tr v khe h khi lp ghp. Thm vo ch A ch ren ngoi, ch B ch ren trong- 1A, 1B : c khe h lp ln nht, thng dng trong nhng mi trng c nhiu bi bn- 2A, 2B : khe h trung bnh v c dng ph bin nht trong cc mi ghp bng bulong v vt- 3A, 3B : c kn kht cao nht, dng cho nhng mi ghp chnh xc cao1.4. K hiu ren Unified threadDi y gii thch mt s k hiu ren Unified Thread thng gp3/8 16 UNC 2B LH (21) 3/8 : ng knh danh ngha ca ren l 3/8 inch 16 : c 16 ren trn 1 inch UNC : ren bc th 2B : ren l c dung sai cp 2 LH : ren tri (ren phi khng cn ghi) (21) : k hiu lin quan n vic o kim ren theo tiu chun ASME/ANSI 1.3M34 0.0625P 0.1875L (3 STARTS) UNF SPL-EXT (23) 34 : ng knh danh ngha ca ren l 34 inch 0.0625P : bc ren 0.0625 0.1875L : bc xon 0.1875 (3 STARTS) : ren 3 u mi UNF : ren bc mn SPL : ren c bit (special) EXT : ren ngoi (external) (23) : k hiu lin quan n vic o kim ren theo tiu chun ASME/ANSI 1.3M2. Ren tam gic h Met2.1 Gii thiuRen tam gic h Met c dng ph bin Vit Nam v nhiu nc khc trn th gii. c tnh k thut ca loi ren ny c qui nh trong tiu chun ASME B1.13M-2005 (tng thch vi tiu chun ISO 68 v profile ren v tiu chun ISO 965/1 v dung sai ren).Hnh 2.Profile c bn ca ren tam gic h MetKhc bit c bn ca ren h Met v ren UN l ren h Met s dng profile ren c gc nh 60ov tnh bc ren bng mm thay v tnh s vng ren trn 1 inch chiu di. Bc ca ren h Met c chia lm bc th v bc mn trong ren bc th c u tin s dng trong nhng mi ghp thng thng. Phi hp gia ng knh danh ngha v bc ren ca mt s ren h Met c cho trong bng 2

Bng 2. Phi hp gia ng knh danh ngha v bc ren h Met (trch tiu chun ASME B1.13M-2005)2.2 Dung sai renTiu chun ISO 965-1 qui nh cp chnh xc cho cc yu t hnh hc ca ren nh sau :- ng knh y ren trong : 4, 5, 6, 7, 8- ng knh nh ren ngoi : 4, 6, 8- ng knh trung bnh ren trong : 4, 5, 6, 7, 8- ng knh trung bnh ren ngoi : 3, 4, 5, 6, 7, 8, 9i vi sai lch c bn :- Ren ngoi : e, f, g, h- Ren trong : G, H2.3 K hiu renDi y gii thch mt s k hiu ren h Met thng gpM10 x 1 5g6g LH M10 : ren h met c kch thc danh ngha 10mm 1 : bc ren 1mm (khng cn ghi nu l bc ren th) 5g : dung sai ng knh trung bnh ca ren l 5g 6g : dung sai ng knh nh ren l 6g LH : hng xon tri (hng xon phi khng cn ghi)M42 x 4.5 6g 0.63R M42 : ren h met c ng knh danh ngha 42mm 4.5 : bc ren 4.5mm 6g : dung sai ng knh trung bnh v ng knh nh ren l 6g 0.63R : bn knh bo trn nh nht ti y renM16 x L4 P2 4h6h (TWO STARTS) M16 : ren h met c ng knh danh ngha 16mm L4 : bc xon 4mm P2 : bc ren 2mm TWO STARTS : ren hai u miM6 x 1 4G6G EXT 4G6G EXT : nu buc phi son tho bng ch in hoa th thm EXT ch ren ngoi, INT ch ren trongMJ6 1 4h6h MJ : loi ren c bit c dng trong ngnh hng khng3. Ren thang ACMERen thang c dng nhiu trong truyn ng bi n c nhiu u im v bn v d ch to hn so vi ren vung. Ngy nay trn th gii ph bin ba h thng ren thang l ren thang theo tiu chun ACME (M), ren thang theo tiu chun ISO 2904-1977 v ren thang theo tiu chun DIN 1

Hnh 3 : Profile c bn ca ren thang ACME3.1 Phn loi ren thang ACME- General purpose G : dng vi mc ch thng thng. Loi ren ny c ba cp chnh xc l 2G, 3G v 4G trong cp 2G c u tin s dng- Centralizing C : tng t nh loi G nhng c khe h gia ng knh nh ren trong v ren ngoi nh hn, dng trong trng hp cn hn ch ma sat sn ren v vng thn ren. Loi ren ny c 6 cp chnh xc t 2C n 6C nhng thng khng dng 2 cp 5C v 6C. Tiu chun v 2 loi ren G v C c trnh by trong ASME/ANSI B1.5-1997- Stub : dng trong nhng trng hp yu cu bc ren th v chiu su ren thp. Cp chnh xc ca n tng ng vi cp chnh xc 2G, 3G v 4G ca ren loi G. Tiu chun v ren Stub c trnh by trong ASME/ANSI B1.8-1988

Bng 3 : Phi hp ng knh danh ngha v s ren trn 1 inch ca ren ACME (trch ASME/ANSI B1.5-1988)3.2 K hiu ren thang ACMEDi y gii thch mt s k hiu ren thang ACME thng gp1.750-6-ACME-4C 1.750 : ng knh danh ngha 1.75in 6 : c 6 ren trn 1 inch ACME : ren thang theo tiu chun ASME 4C : cp chnh xc 4 cho ren loi C2.875-0.4P-0.8L-ACME-3G 2.875 : ng knh danh ngha 2.875in 0.4P : bc ren 0.4in 0.8L : bc xon 0.8in ACME : ren thang theo tiu chun ASME 3G : cp chnh xc 3 cho ren loi G 20 Stub ACME-2G M1 : ng knh danh ngha 0.5in 20 : c 20 ren trn 1 inch Stub ACME : ren thang ACME loi Stub 2G : cp chnh xc theo ren loi G M1 : kch thc c hiu chnh theo nhm 14. Ren thang h Met4.1 Gii thiu

Hnh 4. So snh profile ca ren thang ACME v ren thang h Metim khc bit c bn gia ren thang h Met v ren thang ACME l ren thang h Met dng gc sn ren 30othay v 29o. Do s khc bit khng qu ln nn nhiu ngi nhm tng hai loi ren ny l mt, nht l trong lc o kim. V d, ren 1-5 ACME c ng knh danh ngha l 25.4mm v bc l 5.08mm rt d nhm vi ren TR 25 x 5 c ng knh 25mm v bc l 5mmRen thang h Met c ng knh t 8mm n 300mm c tiu chun ha trong hai tiu chun : ISO 2904-1977 v DIN 103. Gia hai tiu chun ny c hai im khc bit c bn nh sau :- Tiu chun ISO qui nh nhiu bc ren cho mt ng knh danh ngha trong khi tiu chun DIN ch qui nh mt bc ren cho mt ng knh danh ngha- Tiu chun ISO p dng khe h nh nhau i vi ng knh nh v ng knh y ren trong khi tiu chun DIN khe h ca ng knh y ren ln hn t hai n ba ln so vi khe h ca ng knh nh ren

Bng 4 : Phi hp ng knh danh ngha v bc ren ca 2 tiu chun ren thang h Met4.2 K hiuTR 60 x 18 (P9) LH TR : ren thang 60 : ng knh danh ngha 60mm P9 : bc ren 9mm 18 : bc xon 18 (ren c 2 u mi) LH : ren tri (ren phi khng cn ghi)5. Ren Whitworthy l loi ren do Sir Joseph Whitworth pht minh vo khong gia th k 19. Trc kia ren Whitworth c dng ph bin Anh nhng sau khi Anh thng nht vi M v Canada ban hnh tiu chun ren UN, n hu nh ch cn c dng trong vic ch to nhng linh kin thay th.c trng c bn ca ren Whitworth l profile ren c bo trn c nh v y ren v dng gc nh ren 55othay v 60onh nhng loi ren khc.

Hnh 5 : Profile c bn ca ren Whitworth6. Ren ng ca AnhRen ng ca Anh (British Standard Pipe BSP) tr thnh tiu chun chung v c s dng rng ri trn ton th gii (ngoi tr M dng ren NPT).6.1 Phn loiRen BSP s dng profile ren Whitworth (gc nh 55o) v c chia thnh hai loi theo ng knh ren- Ren ng thng (British Standard Pipe Parallel BSPP) c ng knh ren khng i c k hiu bng ch G- Ren ng cn (British Standard Pipe Taper Thread BSPT) c ng knh tng hoc gim trn chiu di ren c k hiu bng ch R Nu phn loi theo phng php lp ghp, ren BSP c ch to theo hai tiu chun hon ton khc nhau- Tiu chun ISO 7-1 : s ghp kn c to ra gia 2 b mt kim loi, c th kt hp hai b mt ren cn (dng cho ng chu p sut cao) hoc b mt ren cn bn ngoi v b mt ren thng bn trong (dng cho ng chu p trung bnh). Trong tiu chun ny, dy ren R c k hiu nh sau : R : ren ngoi cn Rs : ren ngoi song song dng c bit Rc : ren trong cn Rp : ren trong song song- Tiu chun 228-1 : s ghp kn c to thnh thng qua mt lp m kn. Trong tiu chun ny, dy ren G c k hiu nh sau G : ren trong song song GA : ren ngoi song song c chnh xc cao GB : ren ngoi song song dng trong mc ch thng thng

Hnh 6 :Profile c bn ca ren BSPLu : ng knh ren ghi trong k hiu khng phi l ng knh thc m l ng knh qui c dng trong thng mi. ng knh thc ca ren tng ng vi ng knh dng trong thng mi c cho trong bng

Bng 5 : Kch thc mt s loi ren BSP6.2 K hiuRen BSP c k hiu nh sau :Pipe thread ISO 228 G 2 A LH Pipe thread : ren ng ISO 228 : tiu chun ren G : ren BSPP 2 : ng knh ren A :ren ngoi song song c chnh xc cao LH : ren tri (nu ren phi khng cn ghi)7. Ren ng ng ca M7.1 Phn loiM s dng ren ng theo h thng tiu chun American National Standard Pipe Threads, c khc bit c bn vi ren ng BSP ca Anh l n s dng profile c gc nh 60o. Ren ng ca M c chia lm hai loi chnh theo ng knh ren- National Pipe Taper NPT : ren cn c ng knh tng hoc gim trn chiu di ren- National Pipe Straight NPS : ren thng c ng knh ren khng i trn chiu di renT hai loi ren ny ngi ta cn c th ha thnh nhng loi ren khc ty theo mc ch s dng nh ren NPTR dng trong ngnh ng st, NPSC dng kt ni ng chu p sut thp Chi tit v nhng loi ren ny c th tham kho thm trong s tay Machinerys Handbook, 28th Edition

Bng 6 : Kch thc mt s loi ren NPT7.2 K hiuLoi ren ny c k hiu nh sau :3/8 18 NPT 3/8 : ng knh danh ngha ca ren 18 : c 18 ren trn chiu di 1 inch NPT : ren National Pipe Taper theo tiu chun ANSI/ASME B1.20.1-198318 27 NPTF 1 1/8 : ng knh danh ngha ca ren 27 : c 27 ren trn chiu di 1 inch NPTF : ren Dryseal USA (American) Standard Taper Pipe Thread theo tiu chun ANSI B1.20.3-1976 1 : cp chnh xc 1