Middle-East Journal of Scientific Research 20 (6): 744-748, 2014 ISSN 1990-9233 © IDOSI Publications, 2014 DOI: 10.5829/idosi.mejsr.2014.20.06.11372
Design and Fabrication of Rack and Pinion Lift A. Thirugnana m, Praphul da s and Lenin Rakesh Department of Mechanical Engineering, Bharath Institute of Science and Technology, P.O 600073, Chennai, India Abstract: A Rack and Pinion Lift is composed composed of two gears and a Rack and Pinion arrangement. The flat helical gear is the rack and the round helical gear is the pinion. The rack has teeth cut into it and they mesh the teeth of the pinion gear. Also a spur gear is connected to the shaft of the pinion. And this gear is connected to another gear by using a chain drive. One of the spur gear is connected to the shaft of the torque and transfer power by using a chair. The motor is running by use of 12 v battery. A rack and pinion is used to convert between rotary and linear motion. This rack and pinion lift is commonly used in many industrial applications. A rack and pinion lift consists of a rack and a pinion engaging also transfer motion to or from a special kind of spur gear called a rack consisting of series of teeth in a straight line on a flat surface. The invention relates to rack and pinion lifts, which include a lift car which is driven via toothed wheels by means of an electromotor along a rack carried by a lift mast, said car containing a control and maneuver unit for the electric motor with a control and maneuver button set including floor call buttons, landing based call button units being connected to said control and maneuver unit via a ground level unit from which also a power cable leads to the lift car. In associati on with the lift car a sensor device is arranged to indicate passage of teeth of the rack or the toothed toothe d wheel and produce corresponding position impulses, which represent the position of the lift car. A micro computer system is connected for receiving the position impulses and for collecting and storing call impulses from the call units and destination impulses from the button set of the control and maneuver maneuver unit and based upon the position o f the lift car ordering travel direction, r etardation and stop of the lift car. Said micro computer system includes on the one hand a programmable micro computer unit in the lift car with a register for position impulse numbers corresponding to the positionsof the landings, inputs for landings and outputs for controlling controlling operation operation of the the electric motor, on the other hand a micro computer unit scanning the call b utton units with respect respect to their state and associated associated with the ground ground level unit and communicat communicating ing with the programmable micro computer unit in the lift car. Key words: Rack and Pinion arrangement
Rack and pinion lift consists
INTRODUCTION
A Rack Rack and pinion pinion gear syste system m is composed composed of two two gears. The norma normall helical helical gear gear is the the pinion pinion gear and and the stra straig ight ht heli helica call gea gearr is is the the rack rack.. The The rac rack k has has tee teeth th cut cut into into it and they mesh the teeth teeth of the pinion gear. Rack Rack and pinion gear provides a greater feedback and steering sensation sensation [1]. A well well design designed ed mechanis mechanism m such as the rack and pinion pinion gear gear save effort effort and time. time. The rack rack and and pinion is used to convert between rotary and linear motio motion. n. Rack Rack and pinio pinion n can conver convertt from from rotary rotary to linea linearr or from from linea linearr to rotar rotary. y. The The diamet diameter er of the the gear gear
Which represent the position
determines the speed that the rack moves as the pinion turns. Rack and pinion are commonly used in the steering syste system m of cars cars to conver convertt the the rotar rotary y motio motion n to the steeri steering ng wheel wheel to to the the side side to side motion motion in the the whee wheell [2]. [2]. A rack and and pini pinion on con consi sists sts of of a pinio pinion n engag engaging ing and and transferri transferring ng motion to or from a special kind of spur gear, called a rack, ra ck, consisting of a series of teeth in a straight s traight line on a flat flat surface surface.. The The rack rack and and pinion pinion change changess linea linear r motion into into rotary rotary motion, motion, or vice versa versa the rack and pinion is used to convert between rotary and linear moti motion on.. Rack Rack and pinio pinion n can conve convert rt from from rotary rotary to to linear linear or from from linear linear to rotary rotary.. The diamete diameterr of the gear gear
Corresponding Author: A. Thirugnanam, Department of Mechanical Engineering, Bharath Institute of Science and Technology, P.O 600073, Chennai, India.
Middle-East J. Sci. Res., 20 (6): 744-748, 2014
dete determ rmin ines es the the sp speed eed that that the the rack rack mov moves as the the pini pinion on turn turns. s. Rack Rack and and pin pinio ion n are are comm common onlly use used d in in the the stee steeri ring ng syst system em of cars ars to con conver vert the the rot rotary ary moti motion on of to the stee steeri ring ng whe wheel el to to the the side side to to side side motio otion n in the the whee wheel. l. A rack and pinion consists consists of a pinion pinion engaging engaging and transferring motion to or from a special kind of spur gear, called a rack, consisti consisting ng of a series series of teeth teeth in a straight straight line on a flat flat surfac surfacee [3]. [3]. The rack rack and and pinio pinion n changes changes line linear ar moti motion on into into rotar otary y motio otion, n, or vic vice vers versa. a. In a rack rack and and pinio pinion n lift lift system system,, compri comprising sing a lift lift car, car, electro motor means for driving said car along a lift mast via rack and pinion pinion means, a control control unit in said car with a control buttons set including including floor call buttons, buttons, call button units on landings along said mast, means connecti connecting ng said said call call button button units units to said contro controll unit via a ground ground level level unit, unit, the improv improveme ement nt comprisi comprising. ng. The present invention relates to a rack and pinion lift system, system, comprising comprising a lift car car electro electro motor means means for driving said car along a lift mast via rack and pinion means, means, a contro controll unit unit in in said said car car with with a control control button button set including floor call buttons, buttons, call button units on landings landings along said said mast, mast, means means connecting connecting said said call call button button units units to said control unit via a ground level unit. Micro comput computer er controll controlled ed floor call call systems systems are earlier known in connection with fixed wire rope hoist syste ystems ms for for in indoor door appl appliicat cations ions.. To To app applly sim simil ilar ar sys system tems for for aut autom omat atic ic con control trol of rack rack and and pin pinio ion n dri driv ve lif lifts ts in tough tough indu indust stri rial al envi enviro ronm nmen ent, t, buil buildi ding ng site sites, s, exca excava vati tion onss and and the the simi simillar, meet with a number of proble blems. Amon Among g th these ese pro problem blemss tem tempe pera ratture ure and and mois moistu ture re conditions varying within wide limits should be mentioned, as well as corrosive atmosphere in some cases. cases. power power main mainss volta voltage ge variati variations ons often often occur occur due to connectio connection n and disconn disconnecti ection on of great great loads loads and also also the risk for voltage voltage disapp disappear earanc ancee is greate greaterr than normal. normal. The above mentioned mentioned problems can certainly in some cases be remedied by suitable choice of components, but at the same time they necessitate a far going simplification simplification of the signal transmission transmission and its organiza organization tion in order order to to elimi eliminate nate as many many sources sources of error error as possible because of environment [4]. have design designed ed and fabric fabricate ated d Rack Rack Work Done: We have And Pinion Pinion Lift Lift and further further calcula calculatio tions ns are done. done. Rack Rack and pinion pinion mechan mechanism ism are introd introduced uced in lifting lifting mechanism. The major major opera operatio tions ns done done in desig design n and fabr fabricat ication ion of a rack and pinion lifts are as follows:
Cutti utting ng Dri Drilli lling Weldi elding ng Gri Grindin nding g Cutting: Cutting operations are done so as to make the materia materials ls in proper proper dimensi dimensions. ons. The cutting operations operations are
done by the vario various us cutte cutters rs availa available ble in the the market market just just lik like dew dewaalt, lt, bla black ck decc decco or etc etc.. ha hack saw saw are are used sed fo for sof softt iron iron parts parts such such as stai stainles nlesss steels steels [5]. [5]. Drilling: Drilling is a cutting process that uses a drill bit to cut or enlarge enlarge a hole in solid materials. materials. The drill bit is a
multipoint , end cutting tool. It cuts by applying pressure and rotation rotation to the workpi workpiece, ece, which which form formss chip chipss at at the cutting cutting edge edge [6]. [6]. Welding: Welding is a process for joining different
materia materials.weld ls.welding ing joins different different metals metals or alloys with the help of a number number of proce processes sses in in which which heat is is supplied supplied either electrically electrically or by means means of a gas torch.Heat torch.Heat and and pressure pressure are the important important requirement requirement in welding. welding. Welding Welding is classifi classified ed into; into; Gas Gas wel weldi ding ng Arc Arc weld weldin ing g Resi Resist stan ance ce weld weldin ing g Soli olid stat statee weldi elding ng Gas Gas weldi elding ng Gas Welding: It is a fusion welding process.it joins metals metals using the heat of combust combustion ion of and oxygen/ oxygen/air air and fuel gas mixture mixture.. The intense intense heat heat thus produc produced ed
melts melts and fuses fuses togeth together er the edge edgess of the parts parts to to be welded,gene welded,generally rally with the addition addition of a filler me [7]. Grinding: For material removal, the method used in
grinding grinding is called called abrasion. abrasion. In other words, in grinding, grinding, an abrasive abrasive material material rubs rubs against against the metal part and and clears clears or removes tiny pieces of material. The process implies that instead instead of cutting cutting like a lathe bit, bit, the material material is is slowly and steadil steadily y worn worn away. away. This This is because because compar compared ed to the material material being being ground, ground, the abrasive abrasive is harder. harder. The grindi grinding ng wheel wheel actual actually ly acts acts like like many hundre hundreds ds of very small lathe bit, each cutting off some metal. The abrasive abrasive must must be strong strong enoug enough h to bear any any kind of forces acting upon it while grinding. Usually some sort of
Middle-East J. Sci. Res., 20 (6): 744-748, 2014
impact impact shock shock occurs occurs when when the abrasive abrasive comes comes in contact with the material. Grinding abrades material material in a way similar to sanding. sanding. The grinding grinding oper operat atio ion n is per perfo form rmed ed on on a seve severa rall mach machiines nes lik like the the lathe and th the mi mill, wi with th the ap appropriate ad add-on accesso ries, the most important of which is the spindle. Design Calculations: Design of Rack:
Rack-Cast iron Pinion-Cast iron u<390 N/mm² b =30 N/ mm² Calculation of Centre Distance Corresponding Number of Starts:
Z= 3 Z= iZ 24×3=72 Check Whether Z Lies Between 25 and 85
Choose q=11 Assume Assume(( c ) =159 =159 N/mm² N/mm² Assume initially kkd=1 Wheel torque= power × 60÷2 × rpm of the pinion =50×60÷2 ×(50÷24) = 229 Nm
REVISE a and OBTAIN d1
a =0.5 mx (q+z) a =0.5 0.5×5(1 5(11+72 1+72)) =207mm Pitch circle diameter of rack=d1=qmx =11×5 =55mm 5.Vs=V1÷cos
tan =z =z÷q
=0.14÷cos15.25° =3÷11 =0.145m/s lead angl anglee = 15 15.25 .25° V1=pitch line velocity of rack = d1n1÷(60×1000) = ×55×50÷(60×1000) =0.1439m/s SINCE Vs < 4m/s, the [ c] is correct REVISE k,kd and [Mt] for the actual pitch line velocity velo city of the pinion
V2=rack speed(rpm)×lead÷(60×1000) = 50×(2 mx)or zpa÷(60×1000) =50× =50×3× 3× ×5÷( ×5÷(60 60×1 ×1000 000)) =0.03m/s Since V2=0.03m/s<3m/s, kd=1
[Mt] =ko.kd.Mt =1 =1×1×229×10³ =2 = 229×10³ Nmm a =[(z÷q)+ =[(z÷q)+]³v[(5 ]³v[(540÷(z 40÷(z÷q)[ ÷q)[ c] ]².[Mt]÷ ]².[Mt]÷10 10 =[(72÷11)+1]³v[540÷(72÷11)×159.[229×10³÷10] =7.56³v(0.518867)²×(229×10³)÷10 =7.56×18.336 =139mm Calculation of Axial Module
Mx=2a÷(q+z) =2×139÷(11+72) =3.3mm Take mx=5mm (standard)
[Mt]=k.kd.Mt =1×1×229×10³ =229×10³ Determination of Induced Stress:
c=540÷(z÷q)v[((z÷q)+1)÷a]³.[Mt]÷10 =540÷v[(72÷11)+1)÷207]³.229×10³ =82.5×1.03512 =86.9N/m =86.9N/mm²< m²<[[ c]=159 c]=159N/m N/mm² m² b=1.9[Mt]÷m³xqzyv b=1.9[Mt]÷m³xqzyv =1.9×229×10³÷(5³×11×72×0.499) =8.80N/mm²<[ b]=30N/mm² Zeq=z÷cos³ =72÷cos³15.25° =80 yv =0.499(for 80 teeth)
Middle-East J. Sci. Res., 20 (6): 744-748, 2014
Basic Dimensions: Rack:
L =(12.5+0.09 Z)MX =(12.5+(0.09×72)15 =284mm L1=L+35(grinding allowance) =284+38 =319 Number of Threads on Rack
=L1÷ mx =319÷( ×5 × 5) =21 Actual Length of Rack
=21× ×5 =330mm Pitch diameter of the rack=55mm Tip diameter da=d1+2mx =55+(2×5=65 Root diameter df1=d1-2mx-2c =55-(2×5)-2×(0.3×5) =42 Design of Pinion Face Width of the Pinion
=370+(1.5×5) =378mm Root diameter of the pinion df2=(z-2)mx-2c =(72-2)5-(2×0.3×5) =347mm Specification of Rack:
Material- Cast iron Module=1.5mm Cross section=58×25mm Teeth on the rack is adjusted for 86mm Specification of Pinion:
Material-Cast iron Outside diameter=58mm Pitch circle diameter=55mm Circular pitch=4.7mm Module=1.5mm Pressure angle=21° Addendum=1.5mm Dedendum=1.8m Circular tooth thickness=2.35mm Fillet radius=0.45mm Clearance=0.375 Expected Load Can Handle:
P=mgh÷t The power getting in pinion after all reduction
b =0.75 d1 =0 =0.75×55 =42 Pitch circle diameter of pinion,d2=zmx =7 =72×5 =3 =360mm
=38.4 M=? t =5sec(assumed) g =9.8 h =45cm(assumed) m =P×t ÷gh =(38.4×5)÷(9.81×0.45) =43.49kg(including rack weight)
Tip diameter of the wheel,da2=(z+2)mx CONCLUSION
=(72+2)×5 =370mm Maximum pinion diameter de2=da2+1.5mx
Therefore to conclude, we have designed and fabricated Rack And Pinion Lift and further calculations are done. Rack and pinion mechanism are introduced in
Middle-East J. Sci. Res., 20 (6): 744-748, 2014
lifting mechanism. mechanism.Thus Thus we came in to a contradiction co ntradiction that the installation of a lift is not an easy task and high installation cost. As compar compared ed with with the the other other lift liftin ing g mecha mechani nism sm,, rack rack and and pini pinion on lift lift mech mechan anis ism m does does not not need need any any sepa separa rate te machin machinee rooms rooms.. Well Well desig designe ned d Rack Rack and pini pinion on lift liftss are more compact compact and saves effort and time.
REFERENCES
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