DE2441448A1 - DEVICE FOR APPLYING SPRAY COATINGS TO SUBSTRATES - Google Patents

Description

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Augsburg , August 28 , 197k

The British Oxygen Company Limited, Hammersmith House,

London W6 9DX ,. England

Device for applying spray coatings to substrates

The invention relates to an application device

of spray coatings on substrates,

In particular, it is a device for coating all surfaces of a base material

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2UU48

with a coating in a spraying process,

The material to be coated can be rods or tubes made of metal or other material. The invention is particularly suitable, however, for coating pulverulent substrates, when coating pulverulent substrates It is necessary that the coating material can reach the grains of the powder from all sides these receive a uniform coating.

The invention is based on the object of creating a device of the type set out in the introduction which the coating material is sprayed away from an area facing the material to be coated the path that surrounds it,

In order to achieve this object, such a device according to the invention is characterized by a vacuum-tight housing, a hollow cylindrical electrode made of the coating material and arranged therein, and by means which produce a spray of material on the inner surface of the electrode in such a way that it is sprayed off Electrode material strikes the substrate which essentially passes through the electrode along the electrode _{axis 4}

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24-14-8

A preferred embodiment of the invention is Described below with reference to the accompanying drawing, for example, which is a schematic section shows through a spray device according to the invention »

The spray device shown has a housing on that at its upper end a splash 4 and on its lower end has an outlet 6, the latter for operating the device on a suitable vacuum pump is connectable.

The flange * J is designed so that thereon means for feeding the material to be coated into the interior of the housing 2 can be fastened in a vacuum-tight manner. Does it If the material to be coated is a powder, instead of the illustrated closure plate 8, a suitable, not shown, closed hopper attached to the upper end of the device. Should If wires, rods or tubes are covered with the device shown, the closure plate 8 by means for feeding said elongated workpieces through one or more vacuum seals into the Replaced the inside of the housing. For elongated substrates there are also other collecting means than those in the drawing

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Means shown required, the latter are designed for collecting coated powder materials.

The collecting device shown consists of a funnel 10, a slide valve 12 and a collecting chamber 14, in which a collection container 16 is housed «The interior of the collection chamber 14 can be selectively evacuated or with the Outside air can be connected by using either a vacuum pump or outside air Valve 18 is actuated accordingly. The chamber 14 is provided with a vacuum-tight closure 20 through which the collecting container 16 can be brought into or removed from the chamber.

Inside the housing there are two coaxial electrodes 22 and 24, these two electrodes are outside of the housing 2 is connected to a suitable electrical energy source 26, which is a high-frequency alternating voltage supplies. The electrodes and the voltage source are connected in such a way that, during operation, between the two electrodes a glow discharge takes place, which separates material from the inner surface of the two electrodes by means of of a spray mechanism. That of the inner surfaces of the electrodes sprayed electrode material moves to

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Center of the housing 2 where it meets the surface of the powder grains or the wire or other substrate comes into contact, which passes through the housing along the electrode axis. The conditions are chosen so that the coating material when it hits the substrate is bonded to this and a coating completely covering the surface of the substrate form.

If the device is used for covering wires or the like, it can be arranged in any convenient orientation. If, however, powder materials are to be coated , as is the case in the embodiment shown , the housing 2 must be arranged vertically so that the powder grains fall along the axis of the device as a result of gravity »

During the fall, a coating is formed on the powder grains , the thickness of which depends on the degree of spraying of electrode material from the electrodes, the gas pressure prevailing in the housing and the length of time during which the powder grains are exposed to the coating material .

As shown, inside the

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Housing 2 also has a cylindrical grid 28, This • grid is not absolutely necessary and is desired * if provided, if the powder to be coated has a. field-free space should happen. The grid 28 is on Housing 2 grounded so that the field generated by electrodes 22 and 22 does not affect the inside of the grid extends into the space. However, the grid is designed so that most of the from the electrodes sprayed material passed through the grid openings and used to form a coating finds.

The coated powder materials can optionally after appropriate actuation of the slide valve 12 and the

vacuum-tight closure 20 can be removed.

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Claims (1)

Claims 1, / device for applying spray coatings on substrates, characterized by a vacuum-tight Housing (2), a hollow cylindrical electrode (22) arranged therein and consisting of the coating material, and by means which produce a spray of material on the inner surface of the electrode such that this sprayed electrode material onto the material passing through the electrode essentially along the electrode axis Substrate hits, 2, device according to claim I _9, characterized in that the same has a second hollow cylindrical electrode (24) made of coating material, which is arranged coaxially and at the end with respect to the first-mentioned electrode (22), and that the two electrodes each have a pole of one High-frequency AC voltage source (26) are connected,. . . . 3, device according to claim 2, characterized in that that the second electrode (24) has the same diameter as the first electrode. 509810/0 87 9 24414A8 4, device according to one of claims 1 to 3, characterized characterized in that the housing can be connected to the inlet of a vacuum pump, 5, device according to one of claims 1 to 4, characterized in that the electrode axis runs vertically and that above the electrode or the electrodes (22, 24) a closed feed container for powdery substrate is arranged, such that the powder from the Feed container falls down along the electrode axis, 6, device according to claim 5, characterized in that below the electrode or the electrodes (22, 24) a collecting funnel (10) and below it a collecting chamber (14) are arranged, 7, device according to one of claims 1 to 6, characterized by a grounded cylindrical grid (28), which is arranged within the electrode or the electrodes (22, 24) and surrounds the electrode axis. 509810/0879