RU2388398C1 - Mill (design and grinding method) - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: device relates to the field of producing fine powders including nano-sized ones. The device contains a hollow perforated cone-shaped electric motor rotor wherein, the same as in the grinding bowl of a common mill, proceeds disintegration of a substance to produce a nano-sized powder. On the inside the rotor has teeth or spikes performing disintegration of larger substance globules and creating aggressive vortex flows that continue milling the substance to ever smaller particles. Grinding is additionally promoted by vibration of the rotor suspended on magnet bearings during its high-speed rotation; the magnet bearings proper are designed so that to enable correction of the rotor vertical and horizontal microvibrations in accordance with the preset algorithm. Grinding is performed due to simultaneous action of three factors: disintegrating effect of the rotor spikes, aggressive air or gas vortices, rotor microvibration in the longitudinal or crosswise direction. Grinding proceeds within two spaces simultaneously: inside the hollow rotor and in the space between the rotor and the stator. Thanks too the device design peculiarities grinding is performed into two substance fractions at once.

EFFECT: invention enables production of fine powder with dispersity less than 100 micron.

2 cl, 3 dwg

Description

The invention relates to household and industrial equipment and can be used for grinding food products (coffee, grain, herbal medicinal and technical raw materials), as well as in industry and, in particular, to obtain nanopowders.

Mills for grinding coffee are known from the prior art (RU, patent, 2110943, A47J 42/06, A23F 5/08 from 1998.05.20). The coffee grinder (prototype) contains a housing with a grinding bowl. The working body and the impeller are located on the shaft of the electric motor. The housing cover has channels, and the impeller is located under the grinding bowl made of perforated material. An annular protrusion in the form of an upper half of a circular toroid and a labyrinth seal at the inlet of the channels are made on the lid. This eliminates the sticking of ground coffee to the walls and the bottom of the grinding bowl.

The disadvantage of this coffee grinder is the inability to obtain fine grinding, related in particle size to nanopowders.

Known coffee grinder (Chernitsky II, Potapov I.L. Repair of household machines and appliances at home - M .: Mashinostroenie, 1992, p.14), containing a housing, inside of which there is a grinding bowl and an electric motor, located in the center of the bowl a knife mounted on an electric motor shaft. The top is closed by a lid.

The disadvantage of this coffee grinder is the difficulty of removing ground coffee from the cup due to its sticking to the walls and bottom.

The objective of the present invention is to provide opportunities for obtaining on relatively simple devices fine powder with a dispersion of less than 100 microns.

This goal is achieved by the fact that the grinding bowl is replaced by a cone-shaped hollow rotor of an electric motor made with internal ribs-teeth and / or spokes and through holes. The grinding means are knitting needles and a rotor vibrating during rotation. The rotor makes vibrating micromotion, which can be adjusted by magnetic bearings in a given algorithm. A contributing factor to the grinding is the vortices inside the rotor, organized by a loading cylinder, made in the upper part with internal fins and ribs and sucking in air together with the grinding material. The loading cylinder (pipe) can be made long and fall below the middle transverse line of the rotor so that the air (gas) entering through it lifts the grinding material suspended on the narrow bottom of the rotor and prevents it from sticking to the inner parts of the rotor . The same vortex flows lift up small particles of material located in the gap between the outer wall of the rotor and the inner wall of the stator, facilitating the process of their grinding in vortex flows. At the same time, a long loading tube promotes the distribution of inert gas inside the rotor and the creation of more aggressive vortex flows, which improves the disintegration properties of vortex effects on the substance.

When operating a very fine grinding, it becomes necessary (as an explosion prevention and oxidation) to supply an inert gas (nitrogen, carbon monoxide, etc.) to the grinding space of the rotor. To perform this operation, it is enough to bring the tube with the gas exiting from it close to the external opening of the loading funnel or loading tube with blades-ribs and the gas will be sucked into the hole of the tube. For frequently repeated operations of this kind, it is advisable to arrange a nozzle for supplying gas in the cap of the mill, which is blocked by a corresponding valve.

When operating the nanopowder, the loading tube of the rotor is long (lengthen, possibly even almost to a narrow bottom of the rotor), which improves the uniform distribution of inert gas throughout the entire internal volume of the rotor.

The rotor is suspended by rotation on magnetic bearings, made with the ability to adjust the microvibration of the rotor (using electromagnetic pulses) in the vertical and horizontal directions. Mill body is necessarily grounded.

In the constructive plan, when producing very fine powder and especially when collecting it into prefabricated containers, it becomes necessary to make outlet openings of prefabricated tubes with the possibility of sealing them from the external environment with appropriate materials. The purpose of this constructive solution is to prevent the scattering of very small particles of the substance and their targeted pouring into receiving containers. As such a material, synthetic microporous fabrics or even ordinary polyethylene can be used, on the outer surface of which a conductive layer is applied, which makes it possible to localize this part of the device.

In addition, the valves on the exhaust tubes of the mill can be made with the possibility of automatic adjustment by any type of electromechanical device to create an automatic mill control system.

In a brief embodiment, the device can be characterized as follows:

A mill for grinding substances, including an electric motor and a grinding system, characterized in that the rotor of the engine is conical with the possibility of replacing the grinding bowl and the inner surface of the hollow and perforated rotor is made with knitting needles; while in the upper part of the rotor a loading pipe is made with ribs-blades to create an air flow towards the inside of the rotor, and the lower part is made with a support base and a recess for the ball.

A mill, characterized in that the lower and upper magnetic bearings of the rotor, hanging it during rotation, are made with the possibility of regulating the vertical and horizontal microoscillations of the rotor during its rotation in a predetermined algorithm.

A known method of grinding substances (RU 2110943) using a modified grinding bowl and the movement of air created by the impeller mounted on the axis of the engine.

The disadvantage of this method is the inability to obtain powders of less than 100 microns on a mass scale (that is, in a large percentage of the weight of the substance being ground).

The objective of the present invention is to provide a method that allows to obtain a high (mass) yield of powder with sizes less than 100 microns.

The problem is solved by the fact that the grinding is carried out in a specially designed mill, where the disintegrating role of the rotor spokes, the vortex air (gas) flows inside the rotor and the rotor microvibration act as factors for the grinding. In addition, when producing fine powders, an inert gas is introduced into the grinding space to prevent the powder from exploding and oxidizing.

Raw materials are sucked into the grinding bowl (into the inner space of the hollow rotor) through the loading tube and sent to the rapidly rotating spokes (teeth) of the rotor. The resulting small particles of material acquire other aerostatic qualities compared to the feedstock and move along other trajectories, due to which they are involved in the vortex grinding process.

The features of the grinding method also consist in the fact that the process is conducted under the simultaneous influence of three factors: the disintegrating effect of the rotor spokes, aggressive air (gas) vortices, microvibration of the rotor in horizontal and vertical directions. In addition, grinding occurs in two spaces at once: inside the hollow rotor and in the space between the rotor and the stator.

The process includes the following operations:

- preparation of raw materials for grinding;

- loading of raw materials through the loading funnel and the loading pipe of the rotor;

- maintaining the grinding with the given algorithms of rotation and micro-oscillations of the rotor at a given vortex mode inside the rotor, with the given movements of air (gases) through the valves of the tubes that discharge the powders into the collecting containers;

- collection of powders at given modes of movement of air (gases) through the valves of the outlet tubes.

In a brief description, the method can be represented as follows:

A method of grinding a substance, including introducing it into the grinding bowl, using air flows to prevent powder from sticking to the inner surfaces of the grinding device, characterized in that the grinding of the substance is carried out inside a hollow and perforated rotor of an electric motor equipped with teeth (spokes) on the inside, the substance itself for grinding, they draw with the flow of air (gases) inside the rotor, where the factors contributing to the grinding are the impacts of the spokes, rotor micro-oscillations and vortex air flows ha (gas) inside the rotor; while the grinding process is carried out with the possibility of obtaining two fractions of the substance.

The invention is illustrated by drawings 1, 2, 3, where figure 1 shows the device in its entirety, figure 2 shows the rotor in more detail, and figure 3 presents the fundamentally important elements of the stator. Further description will be made with reference to these figures.

Mill 1 (figure 1) includes a housing 2, in which the stator windings 3 and the magnetic bearing 4 are distributed, as well as the outlet tubes 5 (for powder with nanoscale sizes) and 6 for a larger grinding fraction. Both tubes are made with valves changing their position by means of rods 7. In the upper part, the housing ends with projections 8 with a threaded thread for screwing on the cover 9, made with the second magnetic bearing 10 and the sleeve 11. In the upper part of the cover, grooves (not shown) are made for fastening nozzles 12 (using the protrusions 12 ', see figure 3), which created space for the loading funnel 13.

The rotor 14 (figures 1 and 2) is made hollow and perforated with a loading channel (tube) 15, spokes 16 and a supporting base 17.

Outside, the mill body is decorated with a transparent transparent coating, inside of which there are spaces for receiving tanks 18 (for a fine grinding fraction) and 19 (for a larger grinding fraction).

Structurally, the rotor (figure 2) is made collapsible with the upper 20 and lower 21 parts connected by a threaded connection. In the bearing base of the rotor, a recess 22 is made under the ball bearing 23 (ball) of the lower magnetic bearing. The loading tube of the rotor is made with blades 24 to create air movement from top to bottom, that is, inside the rotor.

The fundamental elements of the stator and its housing are presented in figure 3.

The mill operates as follows.

When the voltage is turned on, the rotor 14 rotates on the support ball 23 at low speeds, and at high speeds the rotor is suspended from the magnetic bearing 4 and partially on the magnetic bearing 10. The task of the latter is also to create the most stable rotation in the coupling 11 at high speeds rotor.

The spokes 16 break down the particles of raw materials into smaller parts, which are involved in a larger volume in a vortex process that contributes to the further grinding of the substance, are pushed through the perforations of the rotor into the space between the rotor and the stator, rise up to the tube 5 and exit through it to the collecting tank 18.

Larger particles (when operating at low rotor speeds) in a larger volume fall into the tube 6 and collect in the tank 19.

Before loading the raw materials into the rotor 14, the mill is idled and the rotor rotates when the tubes 5 and 6 are closed with magnetic valves 4 and 10, and then the dose of raw materials prepared according to the fractional composition is fed to the funnel 13 and the quality parameters of the obtained fractions are checked grinding in tanks 18 and 19. If necessary, the rotor rotation mode is changed or adjusted.

When the valves are closed or closed in tubes 5 and 6, grinding continues and the substance is transferred to an increasingly fine fraction.

In the developed mode (meaning the algorithm) of the rotor rotation and the amount of raw material supplied per unit time, the valve positions are set by rods 7 in tubes 5 and 6 and the product is continuously milled in semi-automatic or automatic modes.

Claims (2)

1. Mill for grinding substances, comprising an electric motor and a grinding system, characterized in that the rotor of the engine is made conical with the possibility of replacing the grinding bowl, and the inner surface of the hollow and perforated rotor is made with knitting needles; while in the upper part of the rotor a loading pipe is made with ribs-blades to create an air flow towards the inside of the rotor, and the lower part is made with a support base and a recess for the ball; at the same time, the lower and upper magnetic bearings of the rotor, which suspend it during rotation, are configured to regulate vertical and horizontal microoscillations during its rotation in a predetermined algorithm. 2. A method of grinding a substance, including introducing it into the grinding bowl and using air or gas flows to prevent sticking of the substance to the inner surfaces of the grinding device, characterized in that the grinding of the substance is carried out inside a hollow and perforated rotor of an electric motor equipped with teeth or spokes on the inside, moreover, the grinding substance itself is pulled with the flow of air or gases into the rotor, where the factors contributing to the grinding are the impacts of the spokes, the oscillations of the rotor and vortex flows of air or gases inside the rotor; while the grinding process is carried out with the possibility of obtaining two fractions of the substance.

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