24-09-2012, 12:17 PM
DESIGN AND ANALYSIS OF BEARINGS FOR VIBRATING SCREEN
COMPLETE VIBRATING SCREENS.docx (Size: 4.43 MB / Downloads: 103)
ABSRACT
The project deals with the design and analysis of bearing for the vibrating screen of capacity 2 tones per hour transmitting 5 B.H.P at a speed of 750 rpm. The design is based on the standard design procedure.
In the present work by using the standard design procedure diameter of vibrating screen shaft has been designed. Select the bearing based on shaft diameter from the standard design data and calculate the bearing life. For the safe design, the values obtained from the present design were compared with the values and results of the analysis obtained from the ANSYS package.
When the shaft rotates under no-load conditions, deflections and bending will occur due to critical speed of the shaft and the transverse loads applied on the shaft. To compensate this bending and deflections, shaft is designed such that the frequency and speed of the shaft is within critical limits. In this project the shaft and bearing assembly is modeled using PRO-ENGINEER modeling package. And using ANSYS package fem model of the shaft is developed, meshing of the shaft model is done and response of the model for the load applied is checked. The stresses and the bending moments obtained in the shaft are analyzed to get the design as a safer one. The design related discussions were carried out and conclusions regarding the best design were drawn.
INTRODUCTION
LITERATURE REVIEW
The literature collected mostly from the Bevcon company records and the data which was used in this project is collected from their client. We used the company’s standard procedure for power calculations and counter weight selection and the calculation from the company records. And the literature is collected from the following journals.
Peter.B.Alford [1]: This journal deals with the working and construction of an inclined vibrating screen with eccentric weights. It also consists of study of different types of exciters, different types of motions, and different types of deck mesh materials.
Leon Laudzers, Pits & Quarry [2]: in this article, it outlines the vibrating technology that has given us new products and there are new scalping applications. He has given sizing formula that has been incorporated into the most popular aggregate-flow computer program, making it easier to size vibrating scalping screens.
Sizing the scalper:
The first step in sizing and selecting the scalper is to review the application factors and to analyze how the scalper fits into the process flow. It is important to identify the scalper’s duty and determine what affect it has on other equipment. The scalper’s efficiency will affect the efficiency and capacity of crushers and other vibrating screens. Once all the application criteria, such as feed rates, material gradation, deck opening and efficiency rate are determined, then special application factors are applied to the sizing formula to determine the required deck area. Vibrating scalper sizing formula determines the square footage required for a desired tonnage rate. As mentioned, this formula was developed mainly from field data combined with empirical values corresponding to specific elements of the application.
Jackie Keul, Telsmith [3]:- This journal deals with the using of portable screeners and it outlines the uses of versatile portable screeners are more beneficent when compared with stationary screeners. They had taken a plant having three stationary screeners and replaced with a portable one, the time for installation of stationary screener is avoided completely i.e. , up to four days time is saved and installation expenditure is less. They implemented this portable screener for non-stop sixteen hours working conditions. The fast pack crushing-and-screening system was designed to be a high-tonnage plant that could be quickly and easily moved from one location to another. After arriving at a new site, the system can be set up in about four hours. The system consists of a Pioneer Vanguardstyle jaw plant as the primary crusher; two JCI three shaft horizontal screen plants; two
JCI Kodiak cone plants (one as secondary and one as tertiary); and as many Kolberg conveyors as may be required by the producer.
VIBRATING SCREEN
Introduction
Vibrating screens are used to screen the material to different sizes with the help of the screen the material that are crushed are categorized into various as per the requirement, and then sent to further processes. These are used in cement industries and thermal plants to screen the various sizes of the coal that comes to the screen from the crusher. The required size of the coal are filtered to the bottom of the screen and sent to the next processing section and the remaining material is sent again to the crusher.
Operating Principle
It adjusts the amplitude by tube-shaped violent vibration screen of eccentric shaft and eccentric blocks. The body moves like a circle, in order to make the materials screened.
Construction of machine
The screen basket is of welded, riveted bolted construction. The vibrator assembly consists of a shaft on which unbalanced weights are fixed. This shaft normally runs into special self aligning spherical roller bearing sealed in housing. The spring assembly normally consists of helical spring, or combination of both. Screening decks consists of knitted wire screen cloth or perforated plate grizzly type bar construction. The screen gets tis motion from a electric motor through v-belt drive.
WORKING OF MACHINE
Motor drives the vibrator through v-belt. Rotation of this vibrator causes centrifugal force exerted on the screen basket in the vertical plane and this causes the vibrating basket to obtain vibrating motion. The diameter of the circular motion (twice the amplitude) is fixed by the vibrator and unbalanced weight fixed on it and it is dependent on vibrating weight of the machine. Therefore, any modification in the screen basket or vibrator will disturb the balance of force and thereby the life of machine. The direction of rotation of the vibrator is marked on the machine with normal free floating material and with normal inclination (15 degree to 18 degree), the direction is forward but, material which are difficult to screen (normally wet materials and when sleep deck inclination 15 degree to 30 degree) is provided the direction of rotation is back words special instruction should followed for this type of machine.