GB2156247A

GB2156247A - Apparatus for impregnating objects under vacuum

Info

Publication number: GB2156247A
Application number: GB08507836A
Authority: GB
Inventors: Wilhelm Hedrich
Original assignee: Hedrich Wilhelm Vakuumanlagen GmbH and Co KG
Current assignee: Hedrich Wilhelm Vakuumanlagen GmbH and Co KG
Priority date: 1984-03-27
Filing date: 1985-03-26
Publication date: 1985-10-09
Also published as: GB2156247B; JPS618167A; CH667019A5; FR2561948A1; FR2561948B1; GB8507836D0; DE3411166A1

Abstract

Impregnating agent (20) is fed into the upper region of an impregnating cylinder by way of an annular line (15) and is directed against the walls (1, 11) so as to be distributed over the periphery of the cylinder wall (1) and the periphery of screen wall (11). The impregnating agent (20) is spread over the walls (1, 11) to form thin layers and is degassed while running downwards, The degassed impregnating agent (20) rises from the base (2) of the cylinder and inundates the material (10) to be impregnated. <IMAGE>

Description

SPECIFICATION Apparatus for impregnating objects under vacuum The invention relates to apparatus for impregnating objects under vacuum, having a charging opening which is closable in a sealed manner for material to be impregnated, an extraction opening for evacuating the apparatus and a feed device for impregnating agent.

Impregnating apparatus of this type is used for introducing a fluid impregnating agent, e.g.

synthetic resins or oils, into objects to be impregnated. A typical example is the impregnation of spools with synthetic resins. The advantage of vacuum impregnation is that before the introduction of the impregnating agent into the pores and cavities of the objects to be impregnated the air and other gases must be removed from these cavities by pressure reduction (evacution) to a sufficient extent forthe impregnating agentto be able to fill the cavities completely. For this purpose the impregnating agent must also be sufficiently gasfree for it to be able to absorb residual gases still remaining in the cavities.

In the case of known impregnating cylinders the impregnating agent is fed in at the base of the cylinder or in the vicinity of the cylinder. Degassing of the impregnating agent cannot be carried out during feeding.

The aim of the invention is to provide an impregnating apparatus in which the impregnating agent is effectively degassed as it is poured into the apparatus.

The object is attained according to the invention in that a feed device comprises a plurality of discharge openings which are distributed around a wall in or of the chamber, in the upper area in the vicinity of the container wall and are orientated in such a way that the impregnating agent is directed against the wall.

In a preferred apparatus the impregnating agent runs down the chamber wall in the form of a thin film and is degassed. The diffusion of the impregnating agent to form a thin layer, and thus a layer of large surface area, substantially promotes the discharge of the gas, so that properly degassed impregnating agent accumulates at the base of the chamber and inundates the objects to be impregnated and contained in the cylinder. This advantage is achieved with an extremely modest structural outlay; only the feed device need be built in such a way that it distributes the impregnating agent over the periphery of the chamber.

The feed device advantageously has an annular conduit disposed in the cylinder. This structural embodiment is particularly advantageous since only a sealed passage through the chamber wall is necessary.

In a preferred embodiment of the invention a screen wall is disposed in the vacuum chamber.

This screen wall is preferably used to diffuse the impregnating agent over a surface for degassing purposes. By introducing impregnating agent between the screen wall and chamber wall the effective space is screened by the screen wall from impregnating agent which has possibly not yet been degassed, so that the material to be impregnated is inundated, in conventional manner, from below by impregnating agent. In the case of a design with a screen wall it is advantageous for the degassing space between the screen wall and the cylinder wall to be kept open at the top towards the cylinder space: This is particularly advantageous for extracting gases discharged from the impregnating agent.

The wall or walls are preferably vertical. The impregnating agent rapidly flows down vertical walls, so that even when the impregnating cylinder is filled rapidly the impregnating agent is diffused into a thin layer.

The screen wall can be supported on a grate, the impregnating agent passing through the grate at the lower end of the degassing space present between the screen wall and the cylinder wall and rising into the effective space of the impregnating cylinder on the other side of the screen wall.

The invention will be further described by way of example only, with reference to the accompanying drawing which illustrates diagrammatically an impregnating cylinder. An impregnating chamber comprises a cylindrical outer wall 1, preferably of circular cross-section, which rises up from a downwardly convex base 2. The chamber is closed at the top by a removable cover 3. The cover 3 closes off the cylindrical chamber 4 including the impregnating material degassing chamber 12 from the environment in a sealed manner. An extraction line 6, which leads to a vacuum pump (not shown in the drawing), is connected to an extraction opening 5 in the cover.

An outlet 7, which is closable by means of a valve 8, is provided at the lowest point of the base 2.

A grate 9, which acts as a floor for charging impregnated material 10, is disposed in the chamber 4. A cylindrical screen wall 11, which is parallel to the outer wall 1, also rises from the grate 10. An intermediate space 12, referred to as a degassing chamber, is formed between the walls 11 and 10.

At the upper end of the screen wall 11 there is an upwardly projecting edge 13 which does not, however, reach the outer wall 1, so that a gap 14, by which the degassing space 12 communicates with the cylinder chamber 4, is left between the end 1 3a of the edge 13 and the outer wall 1.

An annular line or conduit 15, which extends around the entire periphery of the cylinder, is disposed at the upper end of the degassing space 12. A feed line 16, which passes through the outer wall 1 in a sealed manner, opens into the annular line 15. The feed line can be closed by a valve 17. In the annular line 15 are provided openings 18 and 19 which are orientated in such a way that impregnating agent discharged from the openings 18 is directed against the screen wall 11 and impregnating agent discharged from the openings 19 is directed against the outer wall 1. This is indicated in the drawing by small arrows.

The impregnating cylinder is used as follows: When the cover 3 is removed material 10 to be impregnated is introduced into the still empty cylinder. Afterthe cylinder has been closed by means of the cover 3 the air contained therein is largely extracted, and gas present in the material 10 to be impregnated, such as air present in pores for example, is also substantially removed. Fluid impregnating agent is then allowed to flow in by opening the valve 17. The fluid is directed against the walls 1 and 11 and runs down these walls as a thin film. Gas dissolved in the impregnating agent 20 passes into the gaseous phase, bubbles first being formed in the fluid which then burst open.

This gas is extracted by way of the extraction line 6.

As the impregnating agent moves downwards its gas content decreases, which is indicated in the drawing by gas bubbles decreasing in size from top to bottom. The impregnating agent passes through the grate 9 at the lower end of the degassing space 12 and first arrives in the space 4a below the grate 9.

After filling the space 4a the impregnating agent rises through the grate openings into the effective space 4b, in which is the material 10 to be impregnated. Impregnating agent is fed in until the material lotto be impregnated is completed inundated. After the material 10 to be impregnated has been inundated the pressure in the inner chamber is increased, for example to the ambient pressure the actual impregnation procedure occurs, since the impregnating agent is forced into previously degassed pores and the like of the material 10 to be impregnated. After a certain impregnation period which depends upon the material to be impregnated and the impregnating agent, the excess impregnating agent is discharged by opening the valve 8 and is fed into a storage container from which it is removed again for further impregnation procedures.

The storage container can be located at any desired position. In particular, it can even be disposed immediately below the impregnating cylinder, it being possible for the storage container and the impregnating cylinder directly connected thereto to form one unit.

Claims

1. Apparatus for impregnating objects under vacuum, comRF3rising a chamber having a sealable charging opening for charging the chamber with material to be impregnated, an extraction opening for evacuating the chamber and a feed device for feeding impregnating agent into the chamber, wherein the feed device comprises a plurality of discharge openings which are arranged around the inner periphery of the chamber in an upper area thereof in the vicinity of a wall and are orientated in such a way that the impregnating agent is directed against the wall as it is fed into the chamber.

2. Apparatus as claimed in claim 1, wherein the wall is a wall of the chamber.

3. Impregnating apparatus according to claim 1 or 2 characterized in that the feed device comprises an annular line which extends along the wall in the upper region thereof and in which the discharge openings are provided.

4. Impregnating apparatus according to claim 1, 2 or 3, characterized in that a screen wall is disposed in the interior of the chamber, spaced from the chamber wall, and the feed device is disposed in the intermediate space between the cylinder wall and the screen wall, the space forming a degassing space and being in communication with the extraction opening.

5. Impregnating apparatus according to claim 4, characterized in that the discharge openings are orientated relative to the screen wall in such a way that the impregnating agent is directed against the screen wall.

6. Impregneting apparatus as claimed in claim 5, wherein the impregnating agent is directed against both the screen wall and the chamber wall.

7. Impregnating apparatus according to claim 4, 5 or 6, wherein a grate is arranged in the chamber above the base of the cylinder, and the screen wall is mounted on the grate, the degassing space communicating, by way of passages in the grate and the space below the grate, with the space for receiving the material to be impregnated.

8. Impregnating apparatus according to any one of claims 4 to 7, characterised in that the degassing space is open at its upper end towards the interior of the chamber.

9. Impregnating apparatus according to any one of the preceding claims, characterized by a vertical, preferably cylindrical wall, in the upper region of which the feed device is arranged.

10. Impregnating apparatus substantially as hereinbefore described with reference to the accompanying drawings.