Drawings of machine parts for course design with explanations

Contents

1. Kinematic calculation of the drive and selection of electric motor

1.1. Electric motor selection

1.2. Kinematic account

2. Design calculation for the strength of gear feathers

2.1. Gear and wheel material selection

2.2. Definition of allowable stresses

2.2.1. Allowable contact stresses

2.2.2. Allowable tooth bending stresses

2.3. Design calculation for strength of closed cylindrical gears

3. Defining Layout Dimensions

4. Low-speed calculation

5. Selection of rolling bearings

6. Calculation of Keyway Connection

List of used literature

Appendix A Specifics

1. Kinematic calculation of the drive and selection of the electric motor

The design of drive devices begins with a kinematic drive, the task of which is to select the catalog of the electric motor, determine the total gear ratio of the drive and break it down into separate gearboxes according to the kinematic scheme. The final issue of this calculation is the determination of the main kinematic (rotation speeds of shafts) and power (powers and torque on shafts) characteristics of the drive.

2. Design Strength Calculation of Gears

The purpose of the design calculation is to determine the geometric dimensions of the transmission, ensuring its operability and reliability under given operating conditions and given resource. Initial data for design calculation are accepted based on results of kinematic calculation of the drive.

Gear and

Wheel Material Selection

For the manufacture of gears, mainly steels are used, subjected to thermal or chemical-thermal strengthening, which allows to obtain high hardness of the tooth surfaces in combination with a softer (viscous) core, which provides sufficient endurance (contact and bending) of the teeth and their resistance to jamming.

The teeth of the improved wheels are cut after heat treatment, which allows for high accuracy and eliminates the need for grinding the teeth. Wheels of improved steels are well worked out. It is recommended to assign more hardness of the wheel by at least 25 units for the beam-and-neck spinning of the teeth. The improvement is also used as a prior operation in surface heat treatment of teeth to improve the mechanical characteristics of the tooth core.

Surface quenching, cementation and nitrocementation with subsequent quenching ensures high hardness and bearing capacity of surface layers of teeth and sufficiently high bending strength of teeth. After heat treatment, the teeth are subjected to finishing operations (grinding, lapping, etc.). These heat treatment methods do not require a difference in the hardness of the gear teeth and the wheel. TVH surface quenching can be used for gears operating with improved wheels to ensure equal strength.

For a reducer the gear wheel and a wheel need to be made of identical steel grades (in this case we choose steel 40XH) with heat treatment.

So, wheels - improvement, hardness of HV 269... 302

T.O. gears - improvement and hardening of HPV, surface hardness HRC 48... 53