TO THE SUBSTANTIATION OF THE STORAGE BUNKER DESIGN FOR A HIGH-ACCURACY VOLUMETRIC DOSING DEVICE

The paper substantiates the design of one of the main components of a high-precision volumetric dosing device for bulk materials - its storage hopper. It is determined that hopper structural design should avoid possible hang-ups of the product processed and maintain rather uniform dense packing of the material on its way to the dosing area. The process of bulk material flow in a storage hopper was studied numerically by discrete element method. It is concluded that hopper design should be axially symmetric, with defect-free walls, and expanding at an angle of 2-4° to its base.

Experimental Studies Of The Specific Load Distribution Of The Mixture Over The Area Of The Inclined Tray

The regularities of specific loading distribution of loose mixture on the area of a working surface of the inclined tray are established in the work. The studies were performed on the experimental setup consisting of a storage hopper and inclined flat trays of different lengths. The material of the study was a grain mixture of winter wheat variety "Myronivska 30". The magnitude of the load was determined using a receiving device, which allowed to obtain the specific load distribution on the width and length of the tray and over time. The specific loading of the tray is uneven in the area of the working surface: the central section is overloaded, and the wall is underloaded. The largest deviations of the specific load at the inlet of the tray, but with length they decrease, approaching a uniform distribution. The specific load profile across the width of the tray is asymmetric and has a local extremum. As the tray length increases, at the certain initial speed and angle, the specific load decreases and the mixture flow slows down. With a constant supply of material from the hopper, there is a gradual accumulation of the mixture in the tray, compaction and growth of the layer, which leads to complete cessation of flow. Uneven loading of the tray occurs due to uneven supply of material from the storage hopper, in which the movement begins. The initial feed varies across the width of the tray and over time, and the nature of the specific load profile formed at the entrance to the tray is preserved for almost its entire length. The movement of the mixture flow in the inclined tray is non-stationary, the specific load varies significantly over the entire surface area and largely depends on the initial conditions of movement. The obtained regularities of specific loading on the working surface area of the tray can be used in the calculation of the modes of loose mixtures movement and substantiation of the equipment parameters for loading the working bodies of machines.

THE EFFECT OF EXTERNAL SUCTION AT THE DUST OUTLET OF A CYCLONE

Cyclone is one of the most commonly used particulate dust collectors in industries. It employs centrifugal force generated by a spinning gas stream to separate the particulate matter from the carrier gas. However, cyclone is efficient to collect coarse rather than fine particulate size fraction. In this regard, a study was carried out to determine the effect of creating more negative pressure at the storage hopper of a 100 mm diameter laboratory scale cyclone. The negative pressure was created by drawing out a small portion of the gas stream by means of an air pump attached to the storage hopper. Results showed that there was exponentially related between the pressure drop (ΔP) and the amount of gas stream drawn at the storage hopper, but with an increment of 2.6% with suction compared to without. Interestingly, it was observed that more of the fine particulate matter was drawn from the gas stream as the suction flow rate increases. This is due to the suction velocity which exceeds the terminal falling velocities of the fine particles size range. There was a reduction by weight in the fine particle emitted from the cyclone ranging between 14% to 52% by introduction of the suction. The finding serves as a basis for future work in reducing fine particulates from a cyclone separator.

Optimisation of a railway sanding system for optimal grain entrainment into the wheel–rail contact

To combat adhesion loss, sand is fired into the wheel–rail contact via a hose using compressed air typically from a storage hopper mounted to the under frame of the train. Many passenger trains in the UK are fitted with stepped braking controllers which range from 1 to 3 with a fourth step being ‘emergency braking’.1 Sand is fired automatically if wheel slip is detected from brake step level 2 upwards.2 Sand is automatically fired when the emergency brakes are applied irrespective of whether low adhesion/wheel slip has been detected.2 For adhesion loss in traction, sand can be applied at the driver’s discretion. Current railway standards2 govern the maximum permissible sand flow rate to protect against wheel/rail isolation of track circuits, but do not address the hose position. This results in a range of hose set-ups across different train types, some of which may not be effective at delivering sand. The work here was carried out using a full-scale laboratory rail–wheel test machine to find the position for the hose and sand flow rates that give optimum sand entrainment to the contact. It was found that ideally the hose should be aimed at the rail or nip and be as close to that contact as safely possible. The use of a 20 mm bore nozzle on the end of a 25 mm bore hose increased sand passing through the contact by up to 70% relative to widely used 25 mm bore hoses without a nozzle. Reduction in sand flow rate below the 2 kg/min threshold significantly reduced the amount of sand entering the contact. It was also shown that relatively small movements in the hose/nozzle from its ideal position and cross winds significantly reduced sand entrainment.

Sampling Mechanism Design and Analysis of Kinematic and Dynamics

Propose a novel way of belt conveyor material sampling.On the basis of sampling theory research ,Design a new type of sample mechanism.It is characterized by effective sample iron ore,coal and other materials on the belt conveyor.Through the study of collision contact characteristics of iron ore , the kinematics simulation experiments were carried out on the designed sampling head by ADAMS,meanwhile the sample head of design parameters were optimized.The result of test shows that the optimal sampling head rotation angular velocity is 340deg/s.when the rotation angular velocity of sampling head between 317deg/s~317.18deg/s,all the materials can be thrown into the storage hopper.

Further Mechanical Aids for the Foundry

New mechanical and semi-mechanical devices put into practice in the foundry between 1942 and 1949 are described. They include in the mass-production shop, the moulding machine, brake block production and a modern knocking-out station, sand preparation and reconditioning and a multiple-belt storage hopper. Mechanization in the jobbing foundry is also discussed.