FEEDER FOR BULK MATERIALS Feeders are applied for feeding bulk materials fiom a container. For instance, there are screw feeders for powders of chemicals and vibratory feeders for granulated linearrelationbetweenacontrollableoperatingvariable,e.g.spee dorminerals.The vibrating amplitude and a feeding output is a useful advantage in application requiring accuracy. The varying characteristics of the material to be fed disturb titis linear relation. Clianges in water content or grain size can cause stickiness or blocking wluch make the operation unsafe.

In mis respect, we examined the characteristics of feeders and made tests with feeders operating on ofourinventionfiledApril251997.(Processesprinciples and feedingandtransportingpiecegoodsandbulkmaterials-for fardier on"hwention I". These feeders combine the avantage of the principes of positive displacement (namely that one feeding stroke or turn runs with a constant feeding volume) and the simplicity of the vibratory feeders. We experienced that these feeders of Invention I could be applied well for feeding and transporting bulk materials. At the same time we experienced an incident making difficulties at me feeding process. Namely, when one of the feeding fittvigs swings in the direction opposite to the material How (me pliase of return), me material can stick to tlus feeding fitting.

For separation the material stuck on, the principle of Invention I is mat at least two fittings clamp the material during me return phase of the third one. For tlus operation, at least three fittings are required (see the claims of me Invention I).

We found that tlus method was not efficient for sticky materials.

Searclung the solution we devised a process and constructed mechanisms proper for implementation of that. This new process comes from the development of the processes of Invention 1, and at the same time it enlumces the teeding output, too.

The new amusement of the feeding fittings is shown in FIGs 1 - 4. For the sake of clear view only the feeding fittings and the container are shown.

FIG. 1 is a vertical view, FIG. 2 is a stepped cut view from above. FIG. 3 is a vertical cut view. FIG. 4. is a perspective view of the arrangement of the feeding fittings.

The basic changes are that there are two feeding fittings, and that file axes of the feeding fittings 5 are not parallel to the plane of material transport 6 therefore those cut it with the angle α. Therefore the feeding fittings 1, 2 forum a trough section narrowing towards the container as shown in FIG. 2. As it can be seen in FIG. 4., one feeding fitting above, one below is provided witli a tab to provide a closed section for the material flow and to prevent material scattering outside tlus section.

There is a cut of size"k"between the horizontal edge of the upper tab and the vertical edge of the other feeding fittings. By application of this cut for improving condition of feeding, a vertical flow component of the rnaterial flow exists in addition to the horizontal flow towards the opening.

The feeding fittings are forced to swiig longitudinally (xi and x2) and laterally(ß angles in FIG. 3) b the programmable power supply (60).

It can be seen that during ti the swings of leave off the container are simultaneous Now the material between the feeding fittings is separated and moving in the required direction. For effective material separation of sticky materials, the friction force between the material and the surface of feeding fitting needs increase during tolus time. For emmple, by application of contrary moments round the axes of feeding fittiys can be applied for generating clamping force F between the fittings.

In thetimingisshownonFIG.6.case, lie periods t2 are for return to the starting position. During this tune two actions have to be made. A separation of the transported material from the surface, and for the next grasp, puslung me feeding fitting in the material. As shown in FIG. 2, the material stuck to the returning feeding fitting is forced to separate, otherwise it would be compressed owing to the convergent mounting.

An other avantage of tlus invente process is mat the compression is the most effective at the entering edges of the feeding fittings, where it is needed for effective separation. Therefore, the lateral camping is more efficient than at feeding fittings mounted parallel, where lateral forces are distributed along the full surfaces.

In outer appearance, the invented feeder shows similarity with the vibratory ones, but there is a basic difference in the operation. At vibratory feeders, die material in its fluidized state beliaves as a tluid and"runs out"from the container. Here the principe of positive displacement stands out, and, for dus reason, there is a unifom volume of feeding defined by the dimensions and swinging amplitudes. Tlierefore the material flow rate varies linearly with the swinging frequency.

FIGs 7-9 are the assembly drawing of the feeders. The means needed for construction are as follows : Two feeding fittings 1,2 mounted to the mounting frame 14 by two assemblies of spring-thread 30, the electromagnetic drive gear including the electromagnet 41 of the clamping force, the electromagnets 42 of the longitudinal swings, the electromagnet armatures 43,44, the feeder housing 20 with rubber sealings of the fittings 16 and the stuffing for the electric cable 50.

Further details in the construction of the feeders: The electromagnetic drive is transmitted to the feeding fittings by arms of tube. The assemblies of spring-thread 30 permit almost frictionless swinging of the feeding assemblies and provide returning force. An advantageous form is disclosed in Invention 1 Here it is shown in FIG. 5 and consists of mi assembly foot 34, four pieces spring-tlueads 34, two pieces stocks of spring-threads 33 and the fitting plate 39.

Essentially, tlus is a mechanism forcing a link of jointed slide, which provides guided and springed deflections along and around the feeding fitting axis 5. nie mounting frame 14 serves for mounting the assemblies of spring thread 30 and the two mounting bolts 15 for electromagnets. For the sake of clear view, me fixing elementsoftheelectromagnetsarenotshownonFIG.7and8.andsetting The well-considered feeder assembly is ill a sealed housing 20. Two screws 21 are for fixing the case to the mounting frame 14. Two bolts 22 on the mounting frame are provided for mounting me feeder to the container. A LIST OF SYMBOLS AND RELATING ELEMENTS USED IN THE DRAWINGS SYMBOLELEMENT fitting11Feeding fitting22Feeding 5 Axis of the feeding fitting 6 Plane of the material transport 7 Container 14 Mounting frame 15 Mounting bolts for the electromagnets 16 Rubber sealing for the fittings 20 Feeder case connectionbetweenthemountingframeandthecase21Screwed ofmounting22Bolt ofspring-thread30Assembly 31Spring-thread 33 Stock of tlle spring-thread 34 Assembly foot holdingplate39Assembly 41 Electromagnet for the camping force 42 Electromagnet for the axial swings assemblyforthefeedingfitting143Armature 44 Armature assembly for the feeding fitting 2 50 Stufftng box for the electric cable 60Programmable power supply Angle between the axis of fitting and the plane of the material transport (5) pt, P2 Angles of the lateral swings of the fittings moveofthefittingsx1(t),x2(t)Axial F (t) Camping force on the material tt Time needed to move the fittings in the direction of material transport t2 Time needed to get tl te fitting into the material