Kỹ thuật nâng - Vận chuyển - Cơ cấu nâng

KYÕ THUAÄT NAÂNG –VAÄN CHUYEÅN CHÖÔNG 5 CÔ CAÁU NAÂNG (MOTIVE POWER OF HOISTING MACHINERY) DAÃN ÑOÄNG MAÙY TRUÏC( motive power of hoisting machinery) DAÃN ÑOÄNG MAÙY TRUÏC(tt)a) Ñoäng cô ñieän (The electric drive) Ñoäng cô ñieän 1 chieàu (a): kích thích song song , noái tieáp, hoãn hôïp => coù khaû naêng ñieàu khieån cao nhöng giaù thaønh lôùn. (D.c motor are provided in three standard types by the way they are excited. These are the series motor, shunt motor, and compound motor) Ñoäng cô ñieän xoay chieàu (b): coù kích thöôùc goïn, giaù thaønh thaáp. Loàng soùc: môû maùy baèng noái sao, tam giaùc (reû hôn) (5). Daây cuoán: môû maùy baèng ñieän trôû phu (4)ï. (Distinction is made between squirrel-cage (5) and wound- rotor a.c. (4) crane motor -The fact that the speed- torque characteristic of the squirrel- case motor is flat as that as of the shunt motor in handling rated loads indicated that the speed changes but little with load. Squirrel- case motors are the most reliable and inexpensive a.c prime mover. -Wound motors are somewhat heavier and larger than squirrel- case ones. At the same time, the losses of energy in windings during the transient periods are smaller in the former than in later) DAÃN ÑOÄNG MAÙY TRUÏC (tt)a) Ñoäng cô ñieän (The electric drive) DAÃN ÑOÄNG MAÙY TRUÏC (tt) b) Ñoäng cô ñoát trong ( internal combustion device) Ñoäng cô xaêng (petrol engine) Ñoäng cô ñiezen. (diezel engine) => Maùy coù phaïm vi hoaït ñoäng lôùn. DAÃN ÑOÄNG MAÙY TRUÏC (tt)c) Ñoäng cô thuûy löïc ( The hydraulic device) Cho pheùp thay ñoåi taàn soá deã daøng;Cho coâng suaát lôùn vôùi kích thöôùc nhoû; Laøm vieäc eâm Hydraulic derive providing motive power for various on hoisting installations are being increasingly used nowadays due to the following advantages: Perfect overload-absorbing potentiality permitting the transmission of high torques by drive of comparatively small size and low mass. Stepless speed control over a wide range Possibility of a gradual reversing along with frequent and quick speed changes. Automatic safeguarding of the machine and hydraulic drive against overloading. Remote control of the machine, automation and mechanization of the process by simple means. Low moment of inertia of rotating mechanical components in spite of high rates of acceleration and retardation Possibility of feeding energy to more than one motion simultaneously Stable performance irrespectively of speed. High resistance of constituent component wear CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY (hand drive hoisting mechanism) Goàm hai loaïi. Ñaët treân maët ñaát: tay quay. Ñaët treân cao: ñóa xích vaø xích keùo. CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY (hand drive hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY (hand drive hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY(tt) The hoisting mechanism consist of a drum spooling a rope suspended from which a load which a weigh Gload,, a gear reduction which an aggregate speed ratio i, and a means of actuating the drive in the form of a lever or operating sheave to which a form P is applied -Let the radius of the lever or that of operating sheave be l and the form exerted by a laborer P. then torque applied is Where m is the number of laborers and  is a factor allowing for a non-uniform application of the force when more than one laborer When the drive is used on the traveling motion the resistance moment on the track wheel axle is The speed ratio of the gear train between the input and output shafts of the mechanism can be determined from Where  is the efficiency of the gear train Ñaëc ñieåm tính toaùn thieát keá: Thieát keá boä truyeàn cho pheùp naâng vaät vôùi löïc tay quay ñaõ xaùc ñònh ( tính tæ soá truyeàn theo ñieàu kieän löïc ) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY (hand drive hoisting mechanism) Caùch tính tôøi quay tay: Cho : Q, M Tính : boä truyeàn. Choïn (caùp) loaïi daây: caùp, xích . Sô ñoà maéc caùp => palaêng , a. Smax -> Sñöùt. Tính vaø choïn daây. Tính caùc chi tieát. Mtg ? Mp ? i ? => hoäp giaûm toác. Phanh (Mf ≥ k.Mx ). CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY (hand drive hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG TAY (hand drive hoisting mechanism) Sô ñoà cô caáu. Ñaëc ñieåm caáu taïo: Hoäp giaûm toác Phanh Khôùp noái Ñoäng cô Tang CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Schematic diagram of an electrically- driven hoisting mechanism -In use are number of typical arrangements for connecting the hoisting drum with the reducer Sô ñoà noái ñaàu tang vôùi hoäp giaûm toác: Khôùp raêng daøi: cho pheùp leäch truïc, deã laép, kích thöôùc lôùn. - The hoisting drum independently supported by two bearing is connected to the reducer through a coupling. Since the drum bearings are independent of the reducer housing, a shaft misalignment is likely to occur during assembly. The possible misalignment can be corrected by using a coupling of the adequate type, e.g, the tooth coupling tolerating considerable shaft misalignment CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Sô ñoà noái ñaàu tang vôùi hoäp giaûm toác: Truïc 2 oå ñôõ: kích thöôùc nhoû, naëng=> khoâng cho pheùp laép rieâng => ít duøng. More compact are the drives in which two or three bearing are use support the hoisting drum shaft which function as the reducer output shaft at the same time -Unfortunately, a two bearing shaft is rather heavy and, further more, any inaccuracy in positioning a shaft bearing interferes with the meshing of reduction gears CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Sô ñoà noái ñaàu tang vôùi hoäp giaûm toác: Truïc 3 oå ñôõ: ñoøi hoûi laép raùp chính xaùc => khoâng cho pheùp laép rieâng => ít duøng. -A triple- supported shaft is even more vulnerable to such inaccuracies. -In either case the reducer cannot be fitted and run in separately from the drum, preventing thus the use of standard parts. Consequently, the two arrangements have failed to spread CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Sô ñoà noái ñaàu tang vôùi hoäp giaûm toác: Baùnh raêng hôû laép treân truïc tang. Baùnh raêng hôû laép treân vaønh tang: chæ uoán. => duøng trong quay tay. In some arrangements the torque is to the drum through an unguarded single gear train. The gear is secured either to the drum shaft (d) or to drum directly (e), then shaft is subject to a bending load only CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Sô ñoà noái ñaàu tang vôùi hoäp giaûm toác: OÅ töïa truïc tang ñaët vaøo ñaàu ra hoäp giaûm toác => kích thöôùc goïn => laø phöông aùn hôïp lyù nhaát. Promising is an arrangement where one of the drum shaft bearing is located inside the reducer output shaft extension (f). It is compact, provides for designing the shafts as statically determinate, and enables the use of standard unit CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN(tt) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Löu yù caùc thoâng soá tính toaùn trong cô caáu naâng. Coâng suaát ñoäng cô: => N=KW Nñc ≥ N1 + CÑ% cho tröôùc => Nñc , nñc , CÑ%. Tæ soá truyeàn: CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Trình töï tính toaùn cô caáu naâng dao ñoäng baèng ñieän. Cho : Q, H, Vn , CD%. Tính : ñaëc ñieåm laø ñaûm baûo vaän toác => trình töï: Böôùc 1  böôùc 5: gioáng vôùi caùc böôùc tính toùan cô caáu naâng daãn ñoäng baèng tay Böôùc 6 : Ñoäng cô: => Nñc Böôùc 7 : Hoäp giaûm toác Böôùc 8 : Phanh CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Quùa trình môû maùy trong cô caáu naâng. CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Quaù trình phanh trong cô caáu naâng. Quaù trình phanh vaät ñang haï töông öùng ngöôïc laïi vôùi quaù trình môû maùy khi naâng. Môû maùy taïo gia toác töông ñöông trong quaù trình phanh taïo gia toác aâm. Hieäu suaát maát maùt  => tham gia quaù trình phanh => laøm Mf  =>  ôû töû soá. CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) Vaäy: Chuù yù: Coâng thöùc vieát cho tröôøng hôïp phanh ñaët taïi truïc I ( ñoäng cô ), neáu phanh ñaët ôû truïc khaùc thì phaûi thay trò soá töông öùng vaøo choå cuûa nñc vaø i. CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN(tt) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN(tt) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) CÔ CAÁU NAÂNG DAÃN ÑOÄNG BAÈNG ÑIEÄN ( electrically- driven hoisting mechanism) ANY QUESTIONS ? ……….. THANK YOU