Gear Project Design

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Transcript of Gear Project Design

BICOL UNIVERSITYCOLLEGE OF ENGINEERING Legazpi City

S U B M I T T E D

T O:

ENGR. MANUEL RUSTRIA,MMEProfessor

S U B M I T T E D

B Y:

RUSSEL JAMES ALAMERBSME4B

LETTER OF TRANSMITTAL

February 11 ,2010

Engr. Manuel Rustria Professor in Charge College of Engineering Legazpi City

I hereby submit this design as a partial fulfillment to the completion of the subject Machine Design 2. Given this day of February 11 ,2010.

Sincerely yours, Russel James O. Alamer

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ACKNOWLEDGEMENT

The designer expresses his deep gratitude and sincere appreciation to those who inspired and helped him in the realization of this design project. To His professor Engr. Manuel Rustria for his valuable advices and suggestions in the designing and calculating process. To his classmates who shared their knowledge and resources in the fulfillment of the project: Fernado Pillejera Jr., Andrew Ferreras, Christian Gongona, Mark Eljun Vibar and Joseph Grimaldo. To his parents Rodolfo and Jonibeth Alamer for their encouragement and financial support. Above all to the Lord Jesus Christ, his God and Savior Who enables the designer to do everything according to His will.

TABLE OF CONTENTS

TITLE PAGEi

LETTER OF TRANSMITTALii

ACKNOWLEDGEMENT ...iii

TABLE OF CONTENTS....iv

STATEMENT OF THE PROBLEM..1

COMPUTATIONS..2

SUMMARY OF THE COMPUTED DIMENSIONS11

SKETCHES.

BIBLIOGRAPHY.13

APPENDICES..14

iv

STATEMENT OF THE PROBLEM PROBLEM 676]A gear reduction unit is to be designed according to the data in the table and the following specifications. Hp 80 Mg 2 Max. ctr. Dist., in. 5 Rpm, Pinion 720 Kind of load Mon. Nsf Minor pulsations, 1.2

The Velocity ratio may be varied by an amount necessary to have whole tooth numbers. The given center distance is the permissible maximum. The teeth are to be 20FD with Np 18 teeth, with 17 as the minimum acceptable. The service is continuous, with indefinite life. Use Buckinghams dynamic-load for average gears.

a) Decide upon the material with its treatment, pitch, and face width. Start outbeing orderly with your calculations so that you do not need to copy all of them for your report. The report should show calculations for the final decision first, but all significant calculations should be in the appendix. These latter calculations should show: that a cheap material cannot be used; that through hardened- steel (minimum permissible tempering temperature is 800F), flame or induction-hardened teeth have all been considered in detail.

b) To complete the design of the gears. A shaft size is needed. At the option ofthe instructor (i) compute shaft diameters for pure torsion only using a conservative design stress as Ss = 6ksi (to cover stress concentration factor, minor bending, on the assumption that the bearings will be quite close to the gears, etc.); or (ii) make a tentative assumption of the distance between bearings, and design the shafts by a rotational procedure. It would be logical for the input and output to be via flexible couplings. Let the shaft material be cold finished AISI 1137. Design the keys for cold-drawn AISI C1118. Use better materials than these only for good reason. c) Determine the dimensions of the hub, arms or webs, and rims and beads of both gears.

d) Make a sketch of each gear (on separate sheets of paper) including on it all dimensions and information for its manufacture. e) At the instructors option (i) choose rolling type bearings, or (ii) design sleeve bearings. f) Decide upon all details of the housing to enclose the gears, with sketches depicting them. g) Your final report should be arranged (1) Title Page; (2) a summary of the final design decisions, computed dimensions, and material specifications; (3) sketches; (4) final calculations; (5) other calculations.

1

COMPUTATIONS]GIVEN: Power = P = 80 hp Gear Ratio=Mg=2 Center distance= Cd=5 Pinion Revolution = N = 720 rpm Kind of Loading = Minor Pulsations Nsf = 1.2 Pressure Angle = = 20 FD Design the gears based on endurance strength SOLUTION: Mw = Mg = 2, since the pinion is the driver. Solving for the diameters: Cd= (Dg+ Dp) 2(5.25)= Dg+ Dp Dg=(10.5)-Dp ..eq.1 Since Mw = Dg/Dp =2, Substitute eq. 1: 2= (10.5-Dp)/ Dp 2 Dp + Dp =10.5 Dp=10.5/3 Dp=3.5 in. Dg=10.5 - 3.5 Dg=7 in. Assuming no. of teeth for pinion, Np = 17 Pd = Np/Dp = 17/3.5= 4.85, use 5 with Pd = 5 and, For Ng: Ng= Pd(Dg) = (7)(5) =35 with Pd = 5, Np = 17, solve for the new diameters, Dp= Np/Pd = 17/5 = 3.4 with Pd=5, Ng= 35, Dg= Ng/Pd

= 35/5 =7 the new Gear ratio,since it can be adjusted, Mg, Mw=Mg= Ng/Np=35/17 =2.0588 the new center distance Cd, Cd = (Dg + Dp)/2 = (7 + 3.5)/2 = 5.25 in. Solving for the Pitch line Speed, Vm, Vm= Dpn

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= [(3.4 in.)(720 rpm)]/(12 in/ ft.) = 640.8849013 fpm For transmitted Load Ft: Ft = 80hp/Vm = [(80hp)(33000 ft.-lb/min-hp)]/ 646.5397681 fpm = 4119.304409 lb. assume face width, b =1.75, [8 < bPd 572 therefore we cannot use that materials. ~END

DESIGN SUMMARYBEARING ~GEAR Rolling Material: Bearing Bore of cut: Type Diameter Outside Diameter BHN: BRG. 304 AISI C1137 with tempering temperature 750F 20mm or .7874 in. Precision cut 52mm or 2.04 in. 269 35 7 in.

No. of Teeth Gear Diameter HUB Material GEAR AND PINION DIMENSIONS tempering temperature 750F AISI C1137 with Hub Diameter 3 in. Center distance 5.2 in. Hub length 3.15 in. Velocity ratio KEY 2.0558 Material AISI C1118 cold drawn Gear ratio 2.0558 thickness 3/8 in. Diametral pitch base 1/2 5 in. (tolerance: -0.0025 in.) Length 3.15 in. Face width 1.75in RIM Addendum: 1/5 in Material AISI C1137 with tempering temperature 750F Thickness: .3518in. Dedendum 1.25/5 in. WEB Working depth 2/5 in. Material AISI C1137 with tempering temperature 750F Thickness .3455in. whole depth 2.25/5 in. ARM N.A. Fillet radius 0.3/5 SHAFT clearance 0.35/5AISI 1137 cold finished Material Shaft Diameter 1 15/16 in (Tolerance: -0.0004 in. -0.0007 in.) ~PINION Material: AISI 4150 with tempering temperature 1200F BHN: 331 HOUSINGCut Type of Precision cut Material Teeth SAE 1045 No. of 17 Height Diameter 10.3.4 in. 2 inches Pinion Length 10 inches HUB Depth 14 inches Material AISI 4150 with tempering temperature 1200F ```For Detail dimensions, see at in. Hub Diameter 2 sketches Hub length 2.74 in. KEY Material AISI C1118 Thickness 1/4 in. Base 3/8 in. (Tolerance: -0.004 in. -0.007 in.) Length 2.74 in SHAFT Material AISI 1137 cold finished 1 11/16 in. (Tolerance: -0.003 in. -0.016 in.) Shaft Diameter BEARING Rolling Bearing BRG. 308 Bore Diameter 40mm or 1.5748 in. Outside Diameter 90mm or 3.5433 in.

BIBLIOGRAPHY 1. V. M. FAIRES, DESIGN OF MACHINE ELEMENTS 4th EDITION, THE MACMILLAN COMPANY, NEW YORK, 1969 2. PSME CODE, THE PSME CODE COMMITTEE, 1984

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APPENDICES

Addendum. The radial distance between the Pitch Circle and the top of the teeth.

Backlash. Play between mating teeth.

Base Circle. The circle from which is generated the involute curve upon which the tooth profile is based.

Center Distance. The distance between centers of two gears.

Circular Pitch. Millimeter of Pitch Circle circumference per tooth.

Circular Thickness. The thickness of the tooth measured along an arc following the Pitch Circle

Clearance. The distance between the top of a tooth and the bottom of the space into which it fits on the meshing gear.

Contact Ratio. The ratio of the length of the Arc of Action to the Circular Pitch.

Dedendum. The radial distance between the bottom of the tooth to pitch circle.

Diametral Pitch. Teeth per mm of diameter.

Face. The working surface of a gear tooth, located between the pitch diameter and the top of the tooth.

Face Width. The width of the tooth measured parallel to the gear axis.

Flank. The working surface of a gear tooth, located between the pitch diameter and the bottom of the teeth

Gear. The larger of two meshed gears. If both gears are the same size, they are both called "gears".

Land. The top surface of the tooth.

Line of Action. That line along which the point of contact between gear teeth travels, between the first point of contact and the last.

Module. Millimeter of Pitch Diameter to Teeth.

Pinion. The smaller of two meshed gears.

Pitch Circle. The circle, the radius of which is equal to the distance from the center of the gear to the pitch point.

10

Diametral pitch. Teeth per millimeter of pitch diameter.

Pitch Point. The point of tangency of the pitch circles of two meshing gears, where the Line of Centers crosses the pitch circles.

Pressure Angle. Angle between the Line of Action and a line perpendicular to the Line of Centers.

Ratio. Ratio of the numbers of teeth on mating gears.

Root Circle. The circle that passes through the bottom of the tooth spaces.

Root Diameter. The diameter of the Root Circle.

Working Depth. The depth to which a tooth extends into the space between teeth on the mating gear.

Kilogram. The kilogram is defined as the mass of international prototype (standard block of platinumiridium alloy) of the kilogram, kept at the International Bureau of Weights and Measures at Sevres near Paris.

Second. The second is defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

Strength. It is the ability of a material to resist the externally applied forces without breaking or yielding. The internal resistance offered by a part to an externally applied force is called *stress.

Stiffness. It is the ability of