Course project on the discipline "Machine parts" on the topic: "Calculation of a single-stage cylindrical reduction gear box"

Contents

Contents:

Introduction

Motor selection and drive power calculation

1.1 Selection of electric motor

1.3 Power calculation of the drive

Gearing Calculation

2.1 Selection of gear material

2.2 Transmission Design Calculation

2.3 Calculation of geometric dimensions of engagement

2.4 Calculation of forces acting in gear engagement

2.5 Gearing check calculation

2.5.1 Check calculation of gear for contact endurance

2.5.2 Check calculation of gearing for endurance by bending stresses

Shaft calculation

3.1 Selection of shaft material

3.2 Design calculation of shafts. Selection of bearings and keys

3.3 Calculation diagram of the gearbox driven shaft

3.4 Construction of curvature and torques

3.4.1 Calculation of shaft for static strength

3.4.2 Calculation of shaft for fatigue strength

Bearing test calculation by dynamic lifting capacity

Check calculation of keys

Selection of reduction gear box parts lubrication

Selection and justification of gearbox main parts fits

Gearbox assembly

Heat calculation of reduction gear box

List of literature

Introduction

Gear reducers - mechanisms with gears, made in the form of separate units. Reduction gears are used to reduce rotation speed and increase torque from input to output shaft. In modern gearboxes, as a rule, helical cylindrical and conical with circular gear teeth are used, which have a large carrying capacity and smooth operation compared to spur gears.

Reduction gears are mono-, two- and three-stage

The gearbox housing determines the mutual location of the gear parts, perceives the arising forces, serves to protect the parts from contamination and provide lubrication. The main requirements for the design of the housing are strength and rigidity.

The gearbox body is usually cast iron (less often welded steel or cast from light alloys). Bosses (i.e. massive lugs) and ribs are provided at bearing locations to increase housing stiffness. As a rule, the housing has a horizontal connector in the plane in which the axes of all the shafts are located, this provides a convenient fence if each shaft is pre-assembled with all the parts on it.

There are structures of reduction gears with permanent housings, in this case, the assembly of parts is carried out through large holes closed by covers.

The shape of the gearbox cast housing can be different:

1) modern - the body outside has smooth surfaces. Tides, ribs, flanges are located inside;

2) traditional - tides, ribs, flanges are made outside.

The modern chassis design has the following advantages over traditional designs:

oil volume increases, which increases stability of its properties over time, reduces temperature peaks during short-term overloads of the reduction gear box;

flanges are excluded - cause of deviation from flatness of parting surfaces and oil leak by connector;

stiffness and vibration acoustic properties of the housing are increased;

the strength of the legs for the fundamental bolts located in the recesses of the housing is increased;

external cleaning is simplified;

deformation of bosses directed towards deflection of shaft reduces skew of bearing track.

 The lower part of the housing (base) is connected to the upper (cover) with bolts installed with a gap, or with screws, less often with studs. Correct arrangement of body parts is fixed by two conical pins. Sometimes cylindrical pins are installed, but this gives a less accurate fixation. Conical pins intended for installation in blind holes shall have a threaded journal or internal thread used to remove the pin during disassembly.

Sealing devices shall not be installed in the joint plane. gasket, since deformation of these gaskets during tightening of bolts does not provide accuracy of dimensions of holes for bearings. The bolts tightening the bosses for the bearing seats should be placed as close to the bearings as possible. To eliminate oil leakage from the reduction gear box through the joint of the housing and the cover, before final assembly, the connector planes are covered with a special paste. In order to facilitate the separation of glued body parts during disassembly, holes for squeezing screws are provided. Screws are screwed into one part of housing and thrust against the other.

Eyes, slots, hooks or load screws (eye - bolts) are provided on the housing for lifting and transportation of body parts and assembled reduction gear.

Reduction gear is secured to plate or frame by screws or studs with nuts. Screws are placed on lugs or in niches of reduction gear box.

Most often, rolling bearings are used as supports of gear shafts. Covers covering bearings are screwed and embedded. Screwed-in covers are more convenient to use, as they provide access to individual bearings for inspection without disassembling the gear box. Embedded covers simplify the design and reduce the weight of the reduction gear, are more aesthetic, however, they can be used only if there is a housing connector.

Gears, as a rule, are made integral with the shaft, and wheels are put on the key section of the shaft with interference. It is possible to fit gears on smooth shafts with high tension, as well as on splined shafts. Assembly of gears with shafts is carried out under press or using temperature deformation.

List of literature

Vorobyov Yu.V., Kavergin A.D. Machine details. - Tambov, TSTU, 2004.

Chernelevsky D.V. and others. Machine details. Textbook, under. ed. Borodina N.A. - M.: Engineering, 1983.

Nichiporchik S.N. Machine details in examples and tasks

Machine details. Atlas of designs edited by Reshetov D.N. 1992

Ivanov M.N., Ivanov V.N. Machine details. Course design. 1975