Drive to hoist for lifting of load

Contents

Job for Course Project

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

1.1. Electric motor selection

1.2. Determination of gear ratios of drive stages

1.3. Determination of torque on drive shafts and diameters of gear box shafts

2. Design Strength Calculation of Gears

2.1 Selection of gear and wheel material

2.2 Determination of allowable contact stresses

2.3. Allowable tooth bending stresses

2.4. Calculation of strength of closed cylindrical gear gears of reduction gears

3. Calculation of shafts for strength

3.1. Preliminary Shaft Calculation

3.2. Input shaft calculation

3.3. Calculation of intermediate shaft

3.4. Output shaft calculation

4. Selection of rolling bearings

4.1. Dynamic Capacity Bearing Selection and Static Capacity Check

4.2. Input shaft

4.3. Intermediate shaft

4.4. Output shaft

5. Calculation of shaft-hub connections

Key No.

Key No.

Key No.

Key No.

6. Selection of drive couplings

Literature

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.

2.1. Gear and Wheel Material Selection

For the manufacture of gears, use 40X steel and thermal treatment improvement + TVH hardening. Hardness of a core is 269...302 HB, the hardness of a surface is 45...50 HRCe, strength σв =900 MPas, a fluidity limit σт =750 MPas.

Calculation of shafts for strength

Shaft material

For shafts, steels with high mechanical characteristics and low sensitivity to stress concentration are used.

The material of the shafts is 40X steel. Material parameters: σв =900 MPas., σ1=410 MPa., τ1=240 MPa., ψσ=0.1, ψτ=0.05.

Calculation of shafts for strength and fatigue resistance

The calculation of shafts for strength is usually carried out in two stages: the first stage is the preliminary calculation of the shaft, which is carried out after determining the main dimensions of the designed transmission for preliminary selection of shaft diameters at the seats of half-couplings, bearings, gears, etc.; the second stage is a refined calculation, carried out on the basis of the finally developed design of the designed object, in order to determine the actual safety factor for the dangerous section of the shaft.

Selection of lubricants and lubrication system

5.1. Selection of lubrication system.

To reduce friction power losses, reduce the intensity of wear of friction surfaces, their cooling and cleaning from wear products, as well as to protect against jamming, gouging, corrosion, reliable lubrication of friction surfaces must be provided. A crankcase system is widely used to lubricate the gears. Oil is poured into the reduction gear case so that the crowns of the wheels are immersed in it. Wheels during rotation are carried away by oil, spraying it inside the body. Oil enters the inner walls of the housing, from where it flows into its lower part. Inside the housing, a suspension of oil particles is formed in the air, which covers the surface of the parts located inside the housing.

5.2.Select lubricant.

The choice of lubricant is based on the experience of the machines. Oils are preferred. For lubrication of worm engagement oil viscosity is selected depending on sliding speed VC = 5 m/s (Table 11.9), and oil grade - aviation MK22 (Table 11.10).

5.3. Lubricating devices.

During operation of the transmissions, wear products gradually contaminate the oil. Over time, it ages, its properties deteriorate. Defective features are increased acid number, increased water content and presence of mechanical impurities. Therefore, the oil poured into the gearbox housing is periodically changed. To replace oil in the housing, a drain hole is provided, which is closed by a plug with a conical thread. Cylindrical threads do not create a reliable seal.

During long-term operation due to air heating, the pressure inside the housing increases. This leads to oil leaking through seals and joints. To avoid this, the internal cavity of the body is communicated with the external environment by installing the perfume (hatch) at its upper point.