GB2348157A

GB2348157A - Treating an elongate element with a liquid

Info

Publication number: GB2348157A
Application number: GB9904997A
Authority: GB
Inventors: David Tee
Original assignee: Acco UK Ltd
Current assignee: Acco UK Ltd
Priority date: 1999-03-04
Filing date: 1999-03-04
Publication date: 2000-09-27
Anticipated expiration: 2019-03-04
Also published as: GB9904997D0; GB2348157B

Abstract

A method of treating an elongate element, such as a pencil 5, with a fluid, such as a varnish, comprising introducing the elongate element into a tank containing the fluid through a sealing washer assembly 3, which makes a substantially fluid-tight seal with the exterior of the elongate element, causing the elongate element to traverse the tank and to exit the tank through a second washer assembly 6 which makes a substantially fluid-tight seal with the exterior of the elongate element, includes a step of generating a localised region of high pressure air at a position adjacent the point at which the elongate element exits the tank. Compressed air may be caused to flow into an annular passage 11 of a housing 9, and thence along the inner face of the mouth 17 of the housing.

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO AN APPARATUS FOR TREATING AN ELONGATE ELEMENT WITH A LIQUID" THE PRESENT INVENTION relates to an apparatus for and a method of treating an elongate element with a liquid. In particular, the invention relates to a method of, and an apparatus for, treating an elongate element formed at least partially from wood with a liquid such as, for example, paint, varnish or a preservative. The invention may have a particular application to the treatment of elements of wood in the form of pencils or crayons, but it is envisaged that the invention may find equal application in the treatment of wood such as the treatment of elongate elements formed of timber.

It has been proposed previously to treat pencils and elements of timber with a liquid, such as paint, varnish or a preservative by passing the elongate elements sequentially through a tank containing the liquid. The elongate elements are introduced into the tank through an appropriate washer located in one side wall of the tank, the washer being of resilient material such that the washer makes a substantially fluid-tight seal with the exterior of the elongate element.

The elongate element passes horizontally through the tank, so that the exterior of the elongate element is exposed to the liquid within the tank. If the liquid is a preservative, some of the liquid soaks into the element passing through the tank, whereas if the liquid is of paint or varnish, some of the paint or varnish clings to the exterior of the element as it passes through the tank.

The element exists from the tank through another washer formed in the opposite side wall. This washer, again, is formed of a resilient material which forms a seal against the exterior of the elongate element. However, the resilient material cannot be biased very firmly against the exterior of the elongate element or else the paint or varnish applied to the exterior of the elongate element would simply be scraped off. Thus, the seal between this particular washer and the exterior of the elongate element is provided with a certain "tolerance"so that the elongate element, as it emerges from the tank, carries an even coating of paint or varnish on its exterior surface.

Because there is a degree of"tolerance"in the washer through which the elongate elements exit from the tank there is, almost inevitably, some"leakage" of liquid from the tank through the washer. This is undesirable.

It has been proposed to overcome this particular problem by sealing the tank containing the liquid, and subjecting the upper part of the tank to a vacuum. The presence of the vacuum within the tank substantially reduces the amount of liquid that will escape through the seal provided by the washer through which the elongate elements exit from the tank, even if there is a substantial"tolerance". However, it has been found that in using a vacuum, air is drawn into the tank and, as a consequence, the air that is extracted from the tank to create the vacuum carries atomised particles of the liquid used to coat the elongate elements. These particles are very difficult to separate out from the air before it is discharged to atmosphere.

The present invention seeks to provide an improved method, and an improved apparatus, that may be utilised to treat elongate elements such as, for example, pencils or the like.

According to one aspect of this invention there is provided a method of treating an elongate element with a fluid, the method comprising the steps of introducing the elongate element into a tank containing the fluid by passing the elongate element through a sealing washer assembly, which makes a substantially fluid-tight seal with the exterior of the elongate element, causing the elongate element to traverse the tank and to exit the tank through a second washer assembly which makes a substantially fluid-tight seal with the exterior of the elongate element, the method comprising the step of generating a localised region of high pressure air at a position adjacent the point at which the elongate element exits the tank.

Preferably the localised region of high pressure air is generated by mounting a substantially tubular housing on the tank adjacent the point at which the elongate elements exit the tank, and causing a stream of air to flow through the tubular housing towards the point at which the elongate elements exit the tank.

The elongate elements may be pencils, and the fluid may be paint or varnish. Alternatively the elements are elements of timber and the fluid is a preservative.

According to another aspect of this invention there is provided an apparatus for treating elongate elements with a fluid, the apparatus comprising a tank, the tank having, in one side wall a washer assembly incorporating a resilient element dimensioned to permit the elongate elements to be introduced into the tank through the washer assembly with a substantially fluid-tight seal between the washer and the element and having, in an opposed side wall, a second washer assembly incorporating a resilient element, the resilient element being adapted to permit the elongate element to exit the tank with a substantially fluid-tight seal, the apparatus further comprising means adapted to generate a localised high air pressure adjacent the washer assembly through which the elongate element may exit the tank.

Preferably the means to generate high air pressure comprise a substantially tubular housing mounted on the tank in alignment with the second washer assembly, means being provided to cause a stream of air to flow through the tubular housing towards the second washer assembly.

Conveniently the tubular housing incorporates means adapted to be connected to a source of compressed air, an annular distribution chamber surrounding the axis of the housing, and a flow passage leading from the distribution chamber to the interior of the housing, the flow passage being dimensioned to cause air to flow from the distribution chamber substantially axially of the housing towards the point at which the elongate elements exit the tank.

Advantageously the flow passage is constituted by a substantially radially inwardly directed lip carried at the end of the tubular housing, and a bell-like mouth formed at the end of a central axial passage formed within the tubular housing, which mouth is located adjacent the inwardly directed lip.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawing which is a schematic sectional view of an apparatus in accordance with the invention for performing the method of the invention.

Referring to the accompanying drawing, a tank 1 is provided which is adapted to contain a liquid, such as paint, varnish or the like. In one side wall 2 of the tank, a washer assembly 3 is provided which incorporates a resilient washer element 4 which is dimensioned to engage the exterior of an elongate element 5, in the form of a pencil or the like, which is introduced horizontally into the tank 1 through the washer. The elongate element 5 forms part of a substantially endless series of elongate elements which are passed horizontally through the tank 1.

Each elongate element 5 exits the tank through a second washer assembly 6 which is mounted in the side wall 7 of the tank opposed to the side wall 2 carrying the first washer assembly 3. The second washer assembly 6 incorporates a resilient element 8 that engages the exterior of the elongate elements 5 as they leave the tank 1. The resilient element 8 does not firmly engage the exterior of the elongate elements 5, but engages the exterior of the elongate elements with a certain"tolerance"so that the elongate elements may exit from the tank 1 through the washer assembly 6 whilst carrying a coating of the liquid that is present within the tank 1. The tank 1 may be provided with a lid.

As thus-far described, the apparatus is conventional.

Mounted on the exterior of the housing 1, and secured to the side wall 7, is a tubular cylindrical housing 9. The cylindrical tubular housing is substantially aligned with the second washer assembly 6. The cylindrical housing 9 has a relatively thick side wall 10. Adjacent the free end of the cylindrical housing 9, an annular passage 11 is formed within the side wall 10.

The annular passage surrounds the axis of the tubular cylindrical housing 9.

The annular passage communicates with a compressed air inlet 12. The annular passage is of substantially rectangular cross-section, and serves to separate a radially inwardly located wall 12, and a radially outwardly located wall 13. The radially outwardly located wall 13 extends in alignment with the exterior wall of the cylindrical housing 9, and terminates with a radially inwardly directed lip 14 which has a substantially planar radially inwardly extending face 15, the face 15 thus lying in a plane which is perpendicular to the axis of the housing 9. The inner wall 12 extends substantially parallel with the outer wall 13 and surrounds a central axial passage 16 which extends through the tubular cylindrical housing. The wall 12 terminates with an outwardly flared bell-like mouth 17 which lies immediately adjacent the planar face 15 carried by the inwardly directed lip 14.

The central axial passage 16 terminates adjacent the second washer assembly 6, and is so positioned that elongate elements 5 exiting the tank I will pass along the passage 16.

It is to be appreciated that when compressed air is supplied to the compressed air inlet 12, the compressed air will flow into the annular passage 11 which acts as a distribution chamber. The air will then flow through the small space defined between the planar face 15 carried by the lip 14, and the outwardly flared bell-shaped mouth 17 carried by the wall 12. The compressed air will flow down the inner curved face of the bell-shaped mouth 17 due to the coanda effect. The coanda effect is an effect that is familiar in fluidics in that a flowing liquid or gas will tend to"cling"to a surface as the liquid or gas flows, if the liquid or gas is at any point initially adjacent that surface. Consequently, the flow of compressed air will follow the contour of the bell-shaped mouth and will be directed axially of the passage 16 towards the second washer assembly 6. The flowing air may entrain with it further air from the atmosphere which will flow into the passage 16.

In any event, as a consequence of the stream of air flowing towards the second washer assembly 6, a localised high pressure zone is created adjacent the exterior part of the second washer assembly 6, and this high pressure zone will tend to cause air to enter the tank 1 if there is any"tolerance"in the seal between the resilient element 8 of the second washer assembly 6, and elongate elements 5 exiting the tank 1 through that second washer assembly.

Because air is effectively forced into the tank 1 due to a localised high pressure zone on the exterior of the tank, it is found that there is a minimum amount of atomised coating particles present in the air that leaves the tank 1.

Whilst the invention has been described with specific reference to the coating of pencils, it is to be appreciated that the invention may prove to be equally applicable to the treatment of other elements formed of wood, including the impregnation of wood with preservative or like.

Claims

CLAIMS: 1. A method of treating an elongate element with a fluid, the method comprising the steps of introducing the elongate element into a tank containing the fluid by passing the elongate element through a sealing washer assembly, which makes a substantially fluid-tight seal with the exterior of the elongate element, causing the elongate element to traverse the tank and to exit the tank through a second washer assembly which makes a substantially fluid-tight seal with the exterior of the elongate element, the method comprising the step of generating a localised region of high pressure air at a position adjacent the point at which the elongate element exits the tank.
2. A method according to Claim I wherein the localised region of high pressure air is generated by mounting a substantially tubular housing on the tank adjacent the point at which the elongate elements exit the tank, and causing a stream of air to flow through the tubular housing towards the point at which the elongate elements exit the tank.
3. A method according to Claim 2 wherein the tubular housing incorporates means adapted to be connected to a source of compressed air, an annular distribution chamber surrounding the axis of the housing, and a flow passage leading from the distribution chamber to the interior of the housing, the flow passage being dimensioned to cause air to flow from the distribution chamber substantially axially of the housing towards the point at which the elongate elements exit the tank.
4. A method according to Claim 3 wherein the flow passage is constituted by a substantially radially inwardly directed lip carried at the end of the tubular housing, and a bell-like mouth formed at the end of a central axial passage formed within the tubular housing, which mouth is located adjacent the inwardly directed lip.
5. A method according to any one of the preceding Claims wherein the elongate elements are pencils, and the fluid is paint or varnish.
6. A method according to any one of Claims 1 to 4 wherein the elements are elements of timber and the fluid is a preservative.
7. An apparatus for treating elongate elements with a fluid, the apparatus comprising a tank, the tank having, in one side wall a washer assembly incorporating a resilient element dimensioned to permit the elongate elements to be introduced into the tank through the washer assembly with a substantially fluid-tight seal between the washer and the element and having, in an opposed side wall, a second washer assembly incorporating a resilient element, the resilient element being adapted to permit the elongate element to exit the tank with a substantially fluid-tight seal, the apparatus further comprising means adapted to generate a localised high air pressure adjacent the washer assembly through which the elongate element may exit the tank.
8. An apparatus according to Claim 7 wherein the means to generate high air pressure comprise a substantially tubular housing mounted on the tank in alignment with the second washer assembly, means being provided to cause a stream of air to flow through the tubular housing towards the second washer assembly.
9. An apparatus according to Claim 8 wherein the tubular housing incorporates means adapted to be connected to a source of compressed air, an annular distribution chamber surrounding the axis of the housing, and a flow passage leading from the distribution chamber to the interior of the housing, the flow passage being dimensioned to cause air to flow from the distribution chamber substantially axially of the housing towards the point at which the elongate elements exit the tank.
10. An apparatus according to Claim 9 wherein the flow passage is constituted by a substantially radially inwardly directed lip carried at the end of the tubular housing, and a bell-like mouth formed at the end of a central axial passage formed within the tubular housing, which mouth is located adjacent the inwardly directed lip.
11. A method of treating an elongate element substantially as herein described with reference to the accompanying drawings.
12. An apparatus for treating an elongate element substantially as herein described with reference to and as shown in the accompanying drawings.
13. Any novel feature or combination of features disclosed herein.