Technical Field

The invention relates to the field of powder metallurgy, in particular, to devices for dosing and conveying of powder materials and can be used in foundries, mining and production of construction materials.

Background Art

There is known a method and device for pneumatic transportation of powder (application JP 56141228 "Pneumatic transportation of powder", published on 04.11.1981). According to the known method, the compressed air sent from an air compressor is mixed with powder sent out through a rotary feeder from a powder hopper in an accelerator and then sent through a pneumatic transport pipe to a reactor or cyclone. At that time, an electromagnetic valve as an opener is opened and closed repeatedly at certain intervals by ON-OFF signals from a timer, and each time the valve is closed, small pressure wave is generated inside the pneumatic transport pipe. The main drawback of the known device is that the powder should be lifted to the level of powder hopper (usually at about two meters height), which requires additional efforts and costs. Besides that the known device cannot be used in foundries, mining and production of construction materials without further improvements for selective feeding and transportation of ferromagnetic particles allowing feeding only ferromagnetic particles from the mixture of powders, or intake of ferromagnetic particle from the liquid environment (e.g. from the bottom of reservoir with water).

There is known a device for transportation of powdered materials using pulsed electromagnetic field (Jacobi S., Schneider R., Tradowsky K. Neues elektrisches Verfahren zur Verdichtung technischer Pulver. - ETZ. Aug. A., 1971, Bd. 92, H. 8, S. 486-488). The known device contains a surge current generator, a pipe, an inducer electrically connected with the surge current generator and a powder container having metallic bottom being placed in the pipe. At actuation of the generator the container is being pushed away by electromagnetic force and moves along the pipe. The device allows to convey powder materials in the pipe at high speed and press them in the container. Disadvantages of this device are low carrying capacity and short range of transportation. There is known powder conveying device using electrostatic force (patent application JP2000095346 "Long-distance powder conveying device using electrostatic force" published on 04.04.2000). The known device contains a tube comprising insulating dielectric material, an electrode having an insulating coating for insulating between adjacent turns of the electrode wound around the outer periphery of the tube, and a high voltage charge supply device electrically connected to this electrode. Powder particles are transported along the inner wall of the tube by means of electrostatic force caused by the high voltage applied to the electrode. Since electrostatic forces appear only on non-metallic materials, the known device cannot be used for transportation of powders with ferromagnetic properties. However the main drawback of the known device its low carrying capacity, which is not sufficient for transportation of powders having heavy particles, for instance 5g/lcm or more.

There is known a device for transportation of ferromagnetic powders by means of pulsed electromagnetic field (patent LV 13551 "Device for conveying and dosing of ferromagnetic powders", published on 20.06.2007). The device contains a powder hopper, a pulse current generator, an inducer and a vertical supply pipeline adapted for transportation of ferromagnetic powder, being provided with pipeline valve and having outlet aperture located above a mould. Ferromagnetic powder from the powder hopper placed above the level of a mould enters the vertical supply pipeline. Periodically, at the moment when the pipeline valve is opened, the pulse current generator is switched on and discharge current is applied to the inducer; the portion of ferromagnetic powder is accelerated by the energy of pulse electromagnetic field and being filled into the mould from top to bottom. Disadvantage of the known technical solution and its embodiments is low productivity due to quite short range of transportation and limited application of the device.

Disclosure of Invention

The objective of the invention is to eliminate the drawbacks of the prior art and to provide a device for conveying and dosing of ferromagnetic powder materials allowing feeding the powder to the supply pipe from a container, or a conveyor belt, located under the pneumatic transport pipe, ensuring selective intake and subsequent transportation of ferromagnetic particles from a mixture of powders, or intake of ferromagnetic particles from a liquid environment (e.g. from a bottom of reservoir with water), while ensuring high carrying capacity and long range of transportation in vertical, horizontal and/or inclined plane.

The defined objective is accomplished by providing the improved device for dosing and conveying of ferromagnetic powders comprising: a supply pipe for conveying ferromagnetic powders, the supply pipe having a first end and a second end situated opposite each other; a capturing means for taking a portion of ferromagnetic powder from a container and conveying this portion of powder into the supply pipe, the capturing means comprising a surge current generator being electrically connected with an inductor; a receiving means adapted to allow receiving and/or unloading the conveyed powder form the device for dosing and/or conveying ferromagnetic powders, wherein the first end of the supply pipe is being provided with a receiving means adapted to allow receiving into the supply pipe the powder from a container, or a conveyor belt located under the first end of the supply pipe; the second end of the supply pipe being connected to another receiving means adapted for unloading the powder; the second end of the supply pipe and/or the receiving means adapted for unloading the powder is being further provided with a means for discharge of air or inert gas from the supply pipe and/or the receiving means adapted for unloading the powder; wherein the supply pipe is being provided with one or more apertures adapted to allow supplying the compressed air or inert gas to the supply pipe above or after a means; the device for dosing and/or conveying ferromagnetic powders further comprising a fluidizing means for fluidizing the powder and conveying it to the receiving means, the fluidizing means comprising a means for supplying a compressed air or inert gas connected to the supply pipe through a valve and aperture or apertures by a pipe 9 so that the compressed air or inert gas can be supplied to the supply pipe from the fluidizing means, the fluidizing means further comprising a means being adapted to allow provision gastight separation between the receiving means and the supply pipe, a sensor being connected to the valve, allowing to detect the moment when the compressed air or inert gas should be supplied to the supply pipe and switch the valve to the open position.

Further, substance of the invention and its various embodiments are described by way of examples with references to the drawings.

Brief Description of Drawings

Fig. l is a schematic illustration of a device for conveying and dosing of ferromagnetic powder; Fig. 2 is a schematic illustration of a device for conveying and dosing of ferromagnetic powder with actuated capturing means;

Fig. 3 is a schematic illustration of a device for conveying and dosing of ferromagnetic powder with actuated fluidizing means;

Fig. 4 is a schematic illustration of another embodiment of a device for conveying and dosing of ferromagnetic powder having a series of capturing means;

Fig. 5 is a longitudinal section of a supply pipe showing direction of apertures for supplying the compressed air to the supply pipe;

Fig. 6 is a perspective view of the supply pipe showing location on spiral line of apertures for supplying the compressed air to the supply pipe;

Fig. 7 is a longitudinal section of the supply pipe with apertures provided with guiding blades;

Fig. 8 is a schematic illustration of embodiment of the device for conveying of ferromagnetic powder in a horizontal or inclined plane.

With reference to figures 1-3, the device for conveying and dosing of ferromagnetic powder comprising:

- a supply pipe 1 for conveying of ferromagnetic powder materials, having one or more apertures 2 adapted to allow supplying the compressed air or inert gas to the supply pipe 1,

- a receiving means (e.g. nozzle) 3 adapted to allow receiving into the supply pipe 1 the powder from a container, or a conveyor belt, being located under the receiving means

(nozzle) 3,

- a capturing means for taking a portion of powder from a container, or a conveyor belt and conveying this portion of powder material into the supply pipe 1, the capturing means comprising a surge current generator 4, an inductor or inductors 5,

- a fluidizing means for fluidizing the powder and conveying it to the receiving means 6, the fluidizing means comprising a means for supplying a compressed air or inert gas 7 (e.g. compressor or container with inert gas), a valve (e.g. air-valve) 8, a pipe 9 for supplying the compressed air or inert gas from the means 7 to the supply pipe 1 through the aperture or apertures 2, a means 10 (e.g. electromagnetic air-valve) adapted to provide airtight (gastight) separation between the receiving means 3 and the supply pipe 1, a sensor 11 for detecting the moment when the compressed air or inert gas should be supplied to the supply pipe 1 and switching the valve 8, being installed on the pipe 9, to the open position to allow supply of the compressed air or inert gas from the means 7 to the supply pipe 1 (the sensor 11 can be an inductive sensor being electrically connected with generator's 4 output and the valve 8, so that the sensor 11 is actuated when electric current passes through the winding of the inductor 5, and switches the valve 8 to the open position),

- a receiving means 6 adapted to allow receiving and/or unloading the conveyed powder form the offered device (e.g. to a mould or mixer),

- a discharge valve 12 for discharge of air or inert gas from the supply pipe 1 and/or the receiving means 6.

The supply pipe 1 has a first end and a second end situated opposite each other, wherein the first end is being provided with the receiving means 3, and the second end of the supply pipe 1 is being connected to the receiving means 6; the second end of the supply pipe 1 and/or the receiving means 6 is being further provided with means 12. According to one embodiment the inductor 5 is a spiral multiple-turn inductor having vertically directed inner cavity adapted for insertion of the first end of the supply pipe 1. The surge current generator 4 is being electrically connected with the inductor 5. However the offered device can be provided with several inductors, for instance with additional flat inductor located coaxially to the pipe 1, under the layer of powder to be supplied to the pipe 1 and/or container with powder (the container having bottom made from material not conducting current); wherein the additional flat inductor and the main inductor 5 are being parallel and concordantly electrically connected with generator 4. The device for dosing and conveying of powder can be provided with more than one cylindrical inductors located around the pipe 1, one above another (Fig. 4), also being parallel and concordantly electrically connected with generator 4 to allow consecutive conveyance of powder by force of electromagnetic field created sequentially by the inductors 5 and 5\

The first end of the supply pipe 1 is being put vertically into the spiral multiple-turn inductor inductor's 5 inner cavity (Fig. 1-3), so that the receiving means 3 are being put in or adjacent to the container for ferromagnetic powder, or the conveyor belt located under the first end of the supply pipe 1. The receiving means 3 are being provided with the means 10. The aperture or apertures 2 are located above or after the means 10, but not higher or further than the level up to which the bottom part of the portion of powder is being conveyed by the electromagnetic field of the inductor 5, wherein the aperture or apertures 2 are located so, that direct or reflected current of the compressed air or inert gas can hit the bottom part of the portion of powder conveyed by the electromagnetic field of the inductor 5. The second end of the supply pipe 1 may have a widening and/or curving adapted to decrease the speed of the flow of fluidized powder and set a direction of conveying for the powder material separated from the gas.

According to the preferred embodiment the aperture or apertures 2 are being made at 27°-35°, preferably 30° to the imaginary central longitudinal axis of the supply pipe 1 (Fig 5). In the embodiment with more than one aperture 2, the apertures 2 are preferably being made on spiral as shown on Fig. 6. The use of aperture 2 made at an angle to the imaginary central longitudinal axis of the supply pipe 1 and located on a substantially spiral line favours more effective capture of powder and its transportation. The aperture or apertures 2 can be provided with guiding blades 13 (Fig. 7) for controlling the direction of a gas flow and ensuring higher speed of powder transportation.

Another embodiment (Fig. 8) is intended for capturing powder from a container, or a conveyor belt located under the supply pipe 1 and conveying it in the horizontal or inclined plane. This embodiment characterized in that the second end of the supply pipe 1 is being connected to a pipe 14, which is mounted at an angle a to an imaginary central longitudinal axis of the supply pipe 1, where 90°<a<180°, so that the powder can be supplied from the pipe 1 to the pipe 14. In this embodiment the pipe 9 is being connected to a first end of the pipe 14 through the valve 8, so that compressed air or inert gas can be supplied to the pipe 14 ensuring piping of fluidized powder through the pipe 14 to the receiving means 6 mounted to the second end of the pipe 14.

The device operates in the following manner. The surge current generator 4 is switched on a preset automatic regime of operation. Pulse current, at a set energy level, is supplied from the surge current generator 4 to the inductor 5 (sequentially to each inductor 5 starting from the lower inductor as shown in fig. 4, to ensure sequential creation of the electromagnetic field along the length of the pipe 1. At the same time the means 10 is opened. Forced by electromagnetic field created by the electric current passing through the inductor 5, a portion of ferromagnetic powder is conveyed from the container (or a conveyor belt located under the receiving means 3) into the supply pipe 1. After a certain period of time (usually 10-100 μ8) supply of electric current to the inductor 5 is ceased. Under its own inertia the portion of ferromagnetic powder travels along the supply pipe 1 some distance. The sensor 11 is actuated. For instance, the electromagnetic sensor 11 is actuated when electric current passes through the winding of the inductor 5, and switches the valve 8 to the open position. The valve 8 is being switched on with delay after actuation of the inductor 5, which is long enough for the portion of powder already supplied to the pipe 1 by the electromagnetic field of the inductor 5 to leave the zone of inductor 5. The means 10 is being closed. The compressed air is supplied from the compressor 7 to the pipe 1 (alternatively the inert gas is supplied from the container with inert gas). The air or gas hits the bottom part of the portion of powder conveyed by the electromagnetic field of the inductor 5, fluidizes this portion of powder and conveys it further to the receiving means 6, where it is stored or unloaded from the offered device. The compressed air or inert gas is discharged through the means 12.

In the embodiment with widening and/or curving of the second end of the supply pipe 1, the speed of the fluidized portion of powder is being decreased while flowing through the widening of the supply pipe. The curving of the supply pipe sets the direction of flow of the powder, which, being heavier than air, falls into the receiving means 6.

The electric current again is supplied from the surge current generator 4 to the inductor 5, the means 10 is opened and the process of dosing and conveying of powder materials is repeated. Duration of pause between current pulses supplied to the inductor 5 is chosen taking into account the size of powder portions, and performance capabilities of the fluidizing means and the device's overall performance capabilities. For instance, the number of pulses can be from 20 to 200 per minute or more.

In the embodiment shown in fig. 8 the same operation principle applies - first forced by electromagnetic field created by the electric current passing through the inductor 5, then under its own inertia a portion of ferromagnetic powder is conveyed from the container, or a conveyor belt located under the receiving means 3 into the supply pipe 1 travels along the supply pipe 1 and enters the pipe 14. The sensor 11 is actuated and switches the valve 8 to the open position. Thus the portion of powder is being conveyed to the receiving means 6 by the compressed air or inert gas.

The offered device for dosing and conveying of ferromagnetic powders allows intake of the ferromagnetic powder, for instance ferrous powder having particles' size 1- 300 μιη, to the supply pipe from a container, or a conveyor belt, located under the supply pipe, ensuring selective intake and subsequent transportation of ferromagnetic particles from the mixture of powders, or intake of ferromagnetic particle from the liquid environment (e.g. from the bottom of reservoir with water), while ensuring high carrying capacity and long range of transportation.