Calculation and design of roller conveyor drive - heading

Introduction

Mechanical engineering has a leading role among other sectors of the economy, since machines perform the main production processes. Therefore, the technical level of many industries largely determines the level of development of engineering.

Improving operational and quality indicators, reducing the time of development and implementation of new machines, improving their reliability and durability are the main tasks of machine builders. The basis of design is no less important for an engineer, as well as the basis of technology for a design engineer. One of the areas of solving these problems is improving design training.

Depending on the complexity and overall dimensions, machines are divided into a number of parts, which consist of separate parts - products made of a material uniform in name and brand, without the use of assembly operations. Distinguish between parts of general and special-purpose vehicles. General-purpose parts include rivets, nut bolts, shafts, axles, gear and friction wheels, pulleys, sprockets, couplings, bearings, springs, housings and many others. In a wide variety of machines, such parts of the same type perform the same functions, which allows you to distinguish their study into an independent field of science - machine parts. Special-purpose parts, such as piston, valve, spindle, lemech, are found only in certain types of machines. The parts form assembly units - articles, the components of which are to be connected to each other at the manufacturer by assembly operations.

The project is a set of technical documents related to the product intended for manufacture or modernization and containing drawings, calculations, description with fundamental justification, layouts, etc. During the design process, the engineer solves a number of complex and diverse tasks. To do this, the designer must be able to perform kinematic, power, strength and other calculations; of the plurality of shapes that can be given to the part, of the plurality of materials having numerous and varied properties, he must choose those that allow the best use of these properties to increase the efficiency and reliability of the product.

A drive is a device that drives a machine or mechanisms of units and assemblies.

Gearbox Gear Calculation

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

The use of computer programs for calculating transmissions expands the amount of information used, allows you to make calculations with the selection of values ​ ​ (variation) of the most significant parameters: the method of thermal treatment or the materials used, the distribution of the total gear ratio between stages, etc.

Calculation of belt transmission

To calculate the belt gear, we will use the CLIN.EXE. program. To simplify the design of the gear box, we will accept the maximum number of belts equal to 4.

After analyzing the results of the calculation, we choose rational options. In this case, the 4th option (axial distance 702mm) is suitable, since it allows to significantly reduce the dimensions of the drive.

Calculation of cylindrical slow-moving stage

The calculation is carried out on the computer using the program CILPER.EXE. The initial data are the torque on the wheel shaft, the rotation speed, the required gear ratio, the service life, the loading cyclogram, the minimum and maximum tilt angle of the teeth. When calculating, we also enter the properties of the gear and wheel materials, a total of 3 pairs of materials for 3 transmission options.

From the obtained options we will choose the most suitable, we will choose option 3, that is, steel grade for transmission with aw = 315mm 40XN

Calculation of cylindrical high-speed stage

The calculation is carried out on the computer using the program CILPER.EXE. The initial data are the torque on the wheel shaft, the rotation speed, the required gear ratio, the service life, the loading cyclogram, the minimum and maximum tilt angle of the teeth. When calculating, we also enter the properties of the gear and wheel materials, a total of 3 pairs of materials for 3 transmission options. And the axial distance from the slow-moving stage.

From the obtained options we will choose the most suitable, we will choose option 3, that is, steel grade for transmission with aw = 315mm 40XN

Shaft check calculations for static and fatigue strength

The main loads on the shafts are transmission forces. The forces on the shafts are transmitted through the parts fitted on them: toothed or worm wheels, pulleys, half-couplings. When calculating, it is accepted that the parts fitted on the shaft transmit forces and moments to the shaft at the middle of its width. Under the action of forces constant in value and direction in rotating shafts, stresses occur that vary in symmetric cycle.

Static strength check is performed in order to prevent plastic deformations during the period of short-term overloads (for example, during start-up, acceleration, reversal, braking, actuation of the safety device).

Refined calculations for fatigue resistance reflect the influence of a type of stress cycle, static and fatigue characteristics of the material, dimensions, shape and state of the surface.

Calculation of shafts is carried out on computers using VAL.EXE. Data preparation for calculation is carried out according to methodological instructions of the department.

Selection and inspection of bearings

Bearings are selected by dynamic lifting capacity at rotation speed. During the construction of the drive or gearbox layout, the bearings have already been preselected by shaft diameter. Therefore, the calculations given are limited to checking the selected bearing and refining its type, diameter and series according to the program PODSCH.EXE The initial data for the calculation of bearings are: bearing installation diagram, required life, safety factor, temperature factor, ring rotation factor, load cyclogram.

Check calculation of keys

In most cases, non-stressed prismatic keys are used in gearboxes to attach wheels and couplings on shafts. Keys with rounded ends are most often used. Slots on shafts for such keys are made with finger cutters. The most dangerous deformation for keys and slots is crushing from torque.

Gear lubrication (method, type, volume)

To reduce friction power losses, reduce the wear rate 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 gear box housing 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. A suspension of oil particles and air is formed inside the housing, which covers the surface of the parts located inside the housing.

Collars as per GOST 875279 are used to prevent oil leakage through shaft supports. They are installed in through covers of bearings of inlet and outlet shafts. Surface of shaft under cuff is hardened, ground and polished.

Gearbox assembly

Assembly consists in connection of all units to each other by means of bolts. Bearing sockets are closed with embedded covers, which do not require threaded fixation. Reduction gear case and cover are connected by bolts tightening at bosses and flanges.

Before connecting the cover to the housing, it is necessary to cover the surface of the housing flange with a thin layer of sealant. After filling of oil check the reducer for tightness.

Frame (Plate) Design

These elements are supporting structures and serve for connection into a single unit of a machine or separate mechanisms, in this case - drive units. They perceive and transmit to the foundation the loads acting on the machine and ensure the correct location of the units during operation.

In addition to strength, support structures must be rigid, since the latter determines the vibration resistance of the machine.

When developing the design of plates or frames, the operational, technological and economic requirements for the machine are taken into account.

The length and width (L and B) are specified along the drawn drive contour. We assign the height of the plate based on the condition of sufficient rigidity based on the design practice of similar structures:, where L is the length of the plate; We round these values according to GOST 663669 according to row Ra40. H = 220 mm .

After H calculation we select the nearest larger channel size (GOST 824089).

Select Profile

Under the main view is a top view. It shows the holes in the legs of the electric motor and reduction gear, the coordinates of their location, which we take from the catalog of motors and from the drawing of the reduction gear.