Course project. Chain conveyor drive. Design of conical-cylindrical gearbox

Contents

Section Name

Terms of Reference

Introduction

1. Kinematic calculations

1.1 Selection of electric motor

1.2 Determination of drive ratio

1.3 Determination of rotation speed and torque on drive shafts

2. Analysis of calculation results on computers

3. Sketched Design

3.1 Preliminary calculation of shafts

3.2 Distance between gear parts

3.3 Selection of bearing types

3.4 Assembly procedure, execution of necessary adjustment works

4. Design of gears and gears

4.1 Cylindrical gear wheel of high-speed shaft

4.2 Slow Shaft Cylindrical Gear

4.3 Pinion Shafts

5. Design of housing parts and bearing covers

6. Bearing calculation

6.1 Calculation of bearings on high-speed shaft

6.2 Calculation of intermediate shaft bearings

6.3 Calculation of bearings on low-speed shaft

6.4 Calculation of bearings on drive shaft

7. Calculation of connections

Calculation of key connections

8. Shaft Strength and Fatigue Test

8.1 Calculation of low-speed shaft

8.2 Calculation of high-speed shaft

9. Selection of lubrication methods and lubricants

10. Calculation of chain transmission

11. Coupling Selection and Calculation

12. Drive Shaft Companion

13. List of literature used

Applications

Introduction

The purpose of the course design is to design the chain conveyor drive. Chain conveyor are intended for transportation of loose and piece cargoes. The traction element is chains, load-carrying - floorings, buckets, trays, shelves, etc.

The presence of chains as a traction element limits their speed (usually ο< 1 m/s), but allows you to have a longer transportation length at a significant productivity.

The main advantages of chain conveyors compared to tape conveyors are the ability to move hot, dusty, large-piece weights at greater angles of inclination of the route or even in the vertical direction, working in heavier conditions.

Rotary motion from electric motor is transmitted through clutch to high-speed shaft of reduction gear box. In addition to transmitting rotational motion, the clutch also compensates for misalignment of the engine shaft and the high-speed gear shaft. Asynchronous motors were widely used as an electric motor. In these engines, a significant change in load causes a minor change in rotor speed.

Components of the drive are an electric motor, a toothed two-stage reduction gear, an elastic clutch on a high-speed shaft and a safety clutch with a sprocket on a slow-speed shaft, a drive shaft with a sprocket.

The drive device is as follows: torque is transmitted from the electric motor to the input shaft of the reduction gear box through an elastic clutch; from output shaft of reduction gear box through safety clutch to drive shaft. Sprocket secured on shaft moves chain onto which load is laid.

Traction sprockets are installed on the drive shaft and drive the chains according to GOST 58881.

You need to perform the necessary calculations, select the best diagram parameters and develop design documentation for the manufacture of the drive:

General view drawing;

Gearbox assembly drawing;

Working drawings of gearbox parts;

Coupling general view drawing;

General view drawing of drive shaft;

Calculation and explanatory note;

Specifications.

Analysis of calculation results on computers

When designing, the optimal parameters of the product should be selected that best meet various, often contradictory requirements: lowest weight, dimensions, cost; highest efficiency; required rigidity, reliability.

The use of computers for gear calculations allows you to make calculations with the search for the values ​ ​ of the most significant parameters: the method of thermal treatment or the materials used (permissible stresses), etc. You must select the best option.

In the PDM application package - machine parts design - the calculation is carried out in two stages. At the first stage, possible design solutions are found and the main quality indicators necessary for choosing a rational option are determined: mass of the mechanism, axial distance, wheel rim material, efficiency factor. When analyzing the results of the calculation, a rational option is chosen.

In the second step, all design parameters required for drawing release and the engagement forces required for shaft calculation and bearing selection are obtained for the selected option.

Gear gears are calculated for several combinations of hardnesses of the working surfaces of the gear teeth and the wheel, corresponding to the thermal treatment method: I - improvement of the gear and improvement of the wheel; II - hardening of HF gear and wheel improvement; III - cementation of gear and wheel.

The weight of the product is most often taken as an optimality criterion. The mass characterizes the material intensity, it is closely related to the dimensions and labor intensity of production, and the cost of the material is a significant part of the cost of the machine.

The choice is made taking into account the following general limitations:

- possibilities of constructive solution of the selected version;

- scarcity of materials;

- technological possibilities of production (availability of appropriate equipment for tooth cutting; with high hardness of the wheel material, finishing operations are necessary: grinding, lapping the surfaces of the teeth);

- proportionality of drive units and parts (electric motor, reduction gear, belt or chain transmission, drive shaft, etc.).

Structural limitations mean, first of all, the possibility of manufacturing gear teeth and ensuring the necessary strength and rigidity of the high-speed shaft, the possibility of placing high-speed stage shaft bearings in the gearbox housing. The higher the gear ratio of the gearbox and the higher the surface hardness of the teeth, the more difficult it is to satisfy the structural limitations.

Analyzing the proposed options, we can conclude: The first 3 options are not suitable, since they have a small hardness and a large axial distance. Variants with 7-9 are also not suitable, since the hardness of the teeth is large, it is difficult to process such wheels and gears, in addition, a small axial distance. Therefore, after analyzing all the parameters, I chose option 5 since in this version the dimensions of the gears are as close as possible.

All calculated parameters are given in Annex 1

Gearbox Design

3.1 Determination of shaft diameters (see [Dunaev Lelikov], c 45)

We will perform preliminary calculation of diameters of different sections of shafts.

Roller bearings are used as supports for all shafts

3.3 Bearing Type Selection and Layout

Ball radial bearings are most often used to support shafts of spur and helical gears of gears and gearboxes. We initially assign light series bearings. If the load capacity is insufficient in the subsequent calculation, then we will accept the bearings of the middle series. With excessively large sizes of ball bearings, conical roller bearings are used as supports of shafts of cylindrical wheels. Conical and worm wheels shall be precisely and rigidly fixed in axial direction. Ball radial bearings are characterized by small axial stiffness. Therefore, conical roller bearings characterized by high axial rigidity are used in power transmissions for shaft supports of conical and worm wheels. Initially, a light series is selected.

For greater unification, all bearings will be tapered roller.

There are 2 schemes for installing bearings: "screwdriver" and "screwdriver."

The design of installation of bearings "at rest" is structurally simplest. It is widely used with relatively short shafts. When installing radial ball bearings in supports, the ratio l/d ≈ 8... 10.

When installing the shaft according to the "screed" scheme, the distance between the bearings can be slightly larger than in the "off-line" scheme: for ball radial l/d ≈ 10... 12, ball radial-thrust l/d < 10, conical roller l/d < 8.

Based on the given data for the high-speed shaft, we select roller conical radial thrust bearings, the installation scheme of bearings is "screed"; for the intermediate shaft, we select roller conical radial thrust bearings, the installation scheme of the bearings is "vraspor"; for the output shaft, we select roller conical radial thrust bearings, the installation scheme is "in kind"; for drive shaft we select ball two-row spherical bearings.

3.4 Assembly procedure, execution of necessary adjustment works

When assembling the conical transmission, the bearings are adjusted first and then the engagement. Axial clearance in radial thrust bearings is adjusted by axial displacement along shaft by means of round splined nut of inner bearing ring. After adjustment, the nut is locked with a multi-deck washer.

When adjusting the engagement, the gear shaft is moved in the axial direction by changing the thickness of the set of thin gaskets between the reduction gear case and the sleeve flange.

On the intermediate shaft, in addition to adjusting the bearings, it is also necessary to perform a conical engagement control, which is carried out by axial movement of the entire assembled set. Adjustment of bearings and engagement is carried out using a set of thin metal gaskets installed under flanges of screwed-in covers. To move the shaft, the gaskets under the bearing covers are moved from one side of the housing to the other, and their total thickness should remain unchanged.

Required axial clearance in bearings on slow-moving shaft is also provided by means of set of adjusting gaskets.

Pinion shafts

Two designs of gear gears are possible: as a whole with the shaft (shaft-gear) and separately from it (nozzle gear). The quality (rigidity, accuracy, etc.) of the gear shaft is higher, and the manufacturing cost is lower than the shaft and the head gear, so most gear gears are integral with the shaft. Nozzle gears are used, for example, in cases where this is due to geometry.

Due to geometrical features, we manufacture gears of cylindrical and conical gears as a whole with the shaft.

Selection of lubrication methods and lubricants

A crankcase system is used to lubricate the gears. Oil is poured into the reduction gear case so that wheel rims are immersed in it. When rotating, the wheels entrain the 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.

At V < 1m/s, the wheels of both stages of the transmission must be immersed in the oil.

Bearings are lubricated with the same oil as gear parts.

During crankcase lubrication of gears bearings are lubricated with oil spatter. Due to the rotation of the wheels, all gear parts and internal surfaces of the walls of the housing are covered with a splash of oil. Oil flowing from wheels, shafts and from the walls of the housing enters the bearing.

Oil access to high-speed shaft bearings is difficult. Therefore, TSIATIM221, GOST 943380 grease is used for their lubrication, which is put into the cavity between the bearings, before their installation. On the inner side the bearing is closed with an oil discharge ring.

To replace oil, a plug with metric thread is provided in the housing. To monitor the oil level, a plug with metric threads is also installed.

Select the type of oil.

Recommended kinematic viscosity for gears by circumferential speed up to 2 m/s at a temperature of 61 ° C - 75 mm2s. According to the table we choose GOST 20799-86 I-HECTARE oil 68

Calculation of chain transmission

Gearbox movement to drive shaft is performed by means of chain transmission. Calculation is performed on the computer, refer to Appendix 1.

Coupling selection and calculation (see [Dunaev Lelikov], c 360)

Often, the coupling requires a certain set of properties, for example, limiting the transmitted load with misaligned shafts. As a safety clutch, we choose a clutch with breaking elements. Couplings of this type are compact and have high operating accuracy. We choose such a coupling since the overloads are random, i.e. emergency cases. (For frequent overloads, a friction clutch is used).

In case of overload, not the conveyor but the drive will fail.

Therefore, the safety clutch is located as close as possible to the overload site. In my case, it is better to combine it with a driven asterisk.

Drive Shaft Companion

The diameter of the end section of the drive shaft is accepted as Ø65 mm, cylindrical. The mounting diameter of the bearings, as for the slow-moving shaft, shall be Ø75 mm. Since the drive shaft is very long, deflections are inevitable and spherical bearings must be used, which are capable of working even with significant ring distortions. Spherical double-row bearings with designation 1215 as per GOST 2842890 were selected.

In order not to unduly complicate the design, the bearing housings are selected as standard (CMM 110 according to GOST 1321880). The covers are designed in a similar way to the bearing covers in the gearbox, but taking into account the special fastening method characteristic of the bearing housing (long screw and nut). The covers are inserted into the housing.

Traction sprockets are welded. Sprocket is connected to shaft.