SU657086A1 - Device for applying coatings on powders - Google Patents

Description

(54) INSTALLATION FOR DRAINING POWDER COATINGS

the layer absorbs the evaporated metal. In order to uniformly coat all grains, the layer must be stirred, and the constituent material will be continuously removed in the working area, i.e. shift at a certain speed along the generator drum to its o-hidden end. To implement these operations, i.e. For mixing the layer and its axio transport and the known installation, this brush auger 1 o

However, this device has a number of drawbacks: the auger screw is difficult to manufacture | use of vra-. a good tidhe nevertheless does not exclude the abrasion of the metallized material, when its test has low mechanical strength; When metallizing hard materials, for example, abraiva powders, the device with a brush screw is not long-lasting and the mixing efficiency of the device is reduced by the measure of the dispersion of the material being processed.

UenL of the invention enhances the durability of the plant, reduces the attrition of powder — achieved by 4to in a coating plant for powder containing a carrier drum, a mechanism for feeding, mixing and axial movement of powder to the carrier surface, a drum, a mechanism for mixing and axial movement of BbrnofiHeH in as an electrode uzp located with a gap along the generator of the drum and electrically connected with a high voltage source. The electrode assembly is made in the form of two rows of parallel conductive plates, the first of which has pdasties with a constant inclination in the radial plane of the drum and faces its surface, and the second is made of plates with an insane inclination predominantly fittHeHHo in the vertical axial plane of the drum and kinematically connected to a device that provides the ability to change the inclination of the plates; The electrode assembly is made in the form of a cylinder of a series of parallel plates, the cylinder being electrically insulated and rotatably mounted on an axled drive axis, and the plates are placed under a cylinder rotatable in a vertical axi (drum plane and connected to a tilt control device.

The electrode assembly is made in the form of a screw auger fixed and electrically isolated on a connected axis with an adjustable drive.

The direct purpose of the proposed design is to carry out non-contact disruption of the grains composing the layer from their circular trajectory in the section of its downward branch so as to ensure the movement of these grains between the points of disruption and return to the previous trajectory not in the dense layer, but in the descending flow i.e. under the influence of gravitational and inertial forces. It is easy to see that during such a movement the mixing of the grains takes place automatically. In addition, it can be intensified by placing a system of obstacles in the form of fixed or moving inclined surfaces on the flow path. By setting these surfaces with the desired direction and degree of inclination, or, respectively, by setting a certain direction and speed of their movement, it is possible to provide a solution to the second task, namely, to obtain the possibility of a controlled displacement of the layer along the drum axis.

The effect of this design is based on the well-known phenomenon of recharging and the self-oscillating motion of solid conductive particles between the electrodes, if a certain potential difference is applied to these electrodes.

Claims (4)

Calculated estimates, as well as model experiments, show that the level of field strength indicated above in the gap is quite sufficient to affect the true size of the order of fractions of mm, i.e. on grains of coarse powders. For smaller ones, the correct effect is increased. The power of the voltage source5 necessary for the operation of the mechanism for mixing and axial movement (PAP) depends on the specific dimensions of the installation, the layer thickness and the grain size, but in order of magnitude is fractions of kilowatts. This is significantly less than the power that heats the layer as a result of metal transfer. With a gap width of about 1 cm, the direction of the source should be within the first tens of kilovolts. Voltages of this level are widely used in vacuum installations, for example for feeding electron-beam evaporators. The specific structural 56 design of the mechanism for mixing and axial movement may depend on the level of intrinsic electrical conductivity of the material of the grains. The level of electrical conductivity required for the effect is low and deliberately overlaps already at the initial stages of the main process, however, the behavior of particles of an OF material for substantially dielectric materials can have a number of features. Such particles are capable of movement only in an uneven field. However, in this case, they are prone to the formation of aggregates (chains) and sticking to the electrodes. Accounting for all such features necessitates the existence of device variants (PAPs), which are not equivalent under specific conditions. The general layout of the units of the proposed installation, as well as versions of its device PAP presented on the drawings. FIG. 1 and 2 schematically show the vertical axial and radial sections of the installation as a whole; in fig. 3 and 4 - types of cross-sections for barbs and a mechanism for mixing and axial movement in a variant that is suitable for working with a powder from materials with an intrinsic conductivity of more than 0.1 (OM - m); in fig. 5, 6 and 7 options for working with less electrically conductive materials, similar cuts. The installation contains a chamber 1, in which containers for bulk material 2 and 3 are installed, evaporators 4, a mechanism for mixing and axial movement S and a drum 6 enclosing these elements. The latter rotates along the arrow B during operation and carries a layer of metallizable material 7 on its inner surface. A reversed screw 8 is fixed along the drum axis, the end of which covers the tip of the feeder tray with bulk material 9. Mechanism 5 is electrically connected to a voltage source (not shown) through a high-voltage input 1O. Presented in FIG. 3.4 The mechanism 5 consists mainly of two, united by a box, rows of conductive plates that are oriented in mutually perpendicular planes. The plates of the first row 11 have a constant inclination in the radial plane of the drum 6 and are arranged with a gap relative to the layer moving with the drum 7. The plates of the second row 12 are equipped with axes 13 and are fixed to rotate in these axes in the axial plane of the drum and interconnected by a pull 14, which connects these plates with their tilt control (not shown). The entire structure of the mechanism 5 is fixed by insulators 15 to the console 16 inserted into the drum cavity and connected through a high-voltage input 1O to a voltage source. Mechanism 5 (FIG. 5) consists of a smooth Electrically conductive cylinder 18 mounted on an axis 17, fastened to the axis by means of insulators 19. A spring-loaded contact 2O adjoins the surface of the cylinder, which rests on insulator 15 and is connected to a source through a high-tension input 10 tension The insulator 15 is mounted on the console 16. On the same console there is installed a bracket 21, which carries the duct 22, a cover mounted on it a row of plates 12 with axles 13 and t 14, as well as the aforementioned cylinder. The entire device is facing the surface of the drum 7 and is located with a gap relative to the drum and lying. on the 7. layer. The axis 17 is provided with a drive (not shown) and is driven in rotation along the arrow G. Mechanism 5 (Fig. 6 -and 7) consists mainly of a helical conductive blade 23 mounted on the axis 17. The blade is fixed by insulators 19 and is connected to a voltage source through a high-voltage input and rests on insulator 15, a sliding contact 2O. The blade is covered by the box 22, which is fixed on the console 16 through the bracket 21. The axis 17 is provided with a drive with a variable rotation speed (not shown) and is driven in rotation along arrow G, in accordance with the direction of rotation of the drum. The installation works as follows. in a way. The chamber 1 is evacuated and maintained under high vacuum, and the drum 6 is driven into rotation in the direction of arrow B. The bulk material from the tank 2 flows along the feeder 9 into the inverted screw 8, by which this material is transported to the bottom of the drum. Here it falls into the annular gap and falls on the conical, and then on the --- cylindrical part of the bearing surface, the speed of rotation of the drum is chosen so as to ensure reliable pressing of the bulk material at all points of the trajectory. Therefore, this material forms a solid k, an olyc layer 7. On a portion of the downward branch of the said trajectory, this layer falls into the zone of action of mechanism 5. The latter, at least part of its elements, is maintained at high potential relative to the chamber, drum and pressed to its inner the surface of layer 7. Due to this, an electrostatic field arises in the gap between the mechanism 5 and the drum (or layer, if it is made of electrically conductive material). This field electrifies or polarizes the layer grains, and the electrification is superficial and the polarization is volumetric. In either case, in an uneven field, the grains are affected by the Coulomb forces depending on the grain size, for example, the weight and the degree of unevenness of the field. These forces are mainly directed toward the center of rotation of the layer, i.e. opposite to the direction of the centrifugal force. With proper selection of the source voltage, the specified seeps tear the layer from its circular path and the grains move to the elements of mechanism 5. There they ocynjecr-VLAYU.T recharge and, moving along the 9th reflecting drum, return to the bearing surface. Moving, then along with this surface the layer passes in the form of evaporators, where it absorbs the evaporated metal. Due to each act of interaction, the slodo with mechanism 5, i.e. on each revolution of the drum, the layer is displaced by a definite distance in the direction of the axis. Thus, the resulting layer trajectory is a cylindrical helix. At the end of the movement along such a helix, the metallized material leaves the drum and accumulates in the container 3. The following is a more detailed description of the TCP device according to the options presented. In the embodiment according to FIGS. 3 and 4, the grains of the bulk material from the layer 7 are subjected to the action of Kulrin forces on the plates of the first row 11 and are slid down onto the plates of the second row 12. The last 14 of the plates are installed with a tilt in the axial plane of the drum. Sliding on these plates, the material is shifted to a distance, the value of which depends on the degree of the specified inclination. Thus, the position of the said gi rod determines the speed of the axial trapport of the layer, and consequently, the residence time of the grains in the metallization zone. In the embodiment of FIG. 5, the role of the first row of plates is performed by the cylinder 18 rotating in arrow D, which alone is maintained at high potential. The rotational speed of this cylinder is chosen from the condition that the action of centrifugal forces should prevent the grains from dropping. (Note that sticking can be discussed only with respect to grains of a substantially dielectric material, and only of those that have not yet been in the form of evaporators, i.e., they do not carry a sheath on a semiconductor 1) the gap between the cylinder and the drum, as in the previous case, causes the grains to collapse from their trajectory and move to the surface of the cylinder 18; In contact with this cylinder, the conductive grains undergo a recharge, which causes a change in the direction of the Coulomb forces. The bottom grains on the same cylinder acquire an impulse tangentially at the separation point. As a result, "the grains are dropped onto the plates 12. The assignment of these plates is similar to the previous one. In the embodiment of Figs 6 and 7 above a high potential, by a helical blade 23; When this blade rotates, an uneven field in the gap between the vacuum tube and the drum acquires the properties of a running along the generators of both electrodes. Moving in such a field, the grains of the bulk material acquire a velocity component in the same direction as the axial transport, the layer, provides. The speed of this transport will depend on the speed of rotation of the above-mentioned blade 23. This installation design greatly expands the capabilities of the process of encapsulation of powders both in the direction of the range of mechanical properties of their material and in the direction of dispersion, which can provide a significant economic effect. Claims. Powder Coater drum, viexaiiHaMb for ggpdchchn, mixing and axial spacing of the powder along the bearing surface 6nf) a ban, differing from the fact that in order to increase the payoff; with a gap along the generator drum, and electrically connected to a high voltage source. 2. Installation “about p. 1, about tl and h and yush so that the electrode node is made in the form of two rows of parallel conducting plates, the first of which has plates with a constant inclination in the radial plane of the drum and is facing to the surface, and the second one is made of plates with a worn inclination, mainly in the vertical-axial plane of the drum ti, kinematically connected with a device that allows the inclination of the pastein to be changed. 3. The installation according to clause J, in connection with this, that the electrode assembly is made in a vice cylinder and a row of para-parallel plates, the cylinder being electrically fixed, isolated and rotatably on the actuated axis, and the plates are placed under the cylinder can be rotated in a vertical-axial plane of the drum and connected to a tilt control device. 4. Installation pop, 1, differs by the fact that the electrode assembly is made in the form of a screw auger fixed and electrically isolated on the axis connected to the adjustable drive. Sources of information accepted. Attention in the examination 1. USSR author's certificate No. 440077, cl. C 23 C 13 / O8, 1974. & f3 12 15 IG To argon upralet} I iWAVT ffWAf h W W 2f 17 13 Zi sixteen sixteen uz./