Mask and masking method

Abstract

 A tubular component 10, particularly a heat-­shrinkable tubular component, is masked over a selected area before surface-treatment of the other areas, by fitting a re-usable masking element e.g 12 to the component 10, the tubular component 10 and/or the masking element 12 resiliently deforming so as to be urged together over the selected area of the component 10.

Description

[0001] This invention relates to a method of masking a selected area or selected areas of tubular components prior to treating unmasked surface areas. The invention also relates to a mask for use in the masking method.

[0002] Hitherto in masking tubular components, masking tape has been applied over the selected areas of the component surface, whether this is the outer surface or the inner surface of the component even though applying masking tape to the inner surface of a tubular component is particularly difficult. Once masked in this manner, the relevant surface or surfaces of the tubular component are treated in the manner required. For example, in the case of heat-shrinkable tubular components of plastics material, the surface treatment may comprise spraying or otherwise depositing a layer of metal or alloy, adhesive coating, paint spraying, sand-or aqua-blasting or surface etching for example.

[0003] In accordance with this invention, there is pro­vided a method of masking a selected area or selected areas of a tubular component prior to treating unmasked surface areas, comprising fitting a re-usable masking element to the tubular component, the tubular component and/or the masking element resiliently deforming so as to be urged together over the selected area or selected areas of the tubular component.

[0004] In this manner the selected area or areas of the tubular component are effectively and securely masked so that the required surface treatment of the component can then be restricted to the unmasked area(s).

[0005] The re-usable masking element may comprise a tubular member for fitting within one end of the tubular component to mask an area of the inside surface adjacent that end. Preferably the inner end of the tubular mask element is chamfered around its inner edge: if a layer of e.g. metal is then applied to the unmasked inside area of the tubular component, when the mask element is removed it leaves a clean edge to the applied metal layer.

[0006] The re-usable masking element may comprise a tubular member for fitting around the outside of the tubular component to mask an area of its outer surface. The masking element may comprise a cap member for fitting to the end of the tubular component, and having inner and outer circumferential skirts for fitting against the inner and outer surfaces of the tubular component.

[0007] Another form of re-usable mask may comprise a flexible or semi-flexible tubular member of resilient material and of outer diameter greater than the inner diameter of the tubular component which is to be masked over a selected area of its inner surface. This tubular mask member can then be folded or kinked along its length, inserted into the tubular component and then allowed to expand under its own resilience so far as the inner diameter of the tubular component will permit, thus pressing firmly against the inner surface of the tubular component over a portion of its circumference.

[0008] Embodiments of this invention will now be des­cribed by way of example only and with reference to the accompanying drawings, in which:

FIGURE 1 is a longitudinal section through an end portion of a heat-shrinkable tubular component shown with a re-usable masking element inserted into one end;

FIGURE 2 is a similar section through the same tubular component shown with a re-usable mask in the form of a cap member fitted to the end of the component; and

FIGURE 3 is an end view of the tubular component shown with a re-usable, tubular mask member which has been kinked along its length and inserted into the end of the component.

[0009] Referring to Figure 1, there is shown a heat-­shrinkable tubular component 10 of plastics material. A re-usable masking element 12 has been inserted into one end of the component 10 to mask a selected area of the inner surface of the component adjacent that end. The masking element 12 comprises a precision-made tubular member, which may be machined or moulded, and is pro­vided with a chamfered edge 14 to its inner end. If the surface treatment which the unmasked area of the tubular component 10 is to receive involves high temperatures, the element 12 is formed of temperature resisting material e.g. PTFE.

[0010] In use, the tubular masking element 12 is pushed into the end of the component 10 to the position shown. The element 12 has a slightly greater outer diameter than the inner diameter of the component 10, but forces the component 10 radially outwards against its own inherent resilience. Thus the masking element is firmly in engage­ment with the tubular component 10 over the selected area, such that this area is effectively and securely masked. The required surface treatment to the unmasked area(s) of the component 10 can then be carried out. If this treat­ment comprises the application of a layer of e.g. adhesive or metal, then the chamfered edge 14 of the masking element ensures that this element can be removed and leave a clean edge to the applied layer of e.g. adhesive or metal: if instead the end of the element 12 was flat, there would be a build up of the applied material of the layer against it, such that the layer would tend to tear at its junction with the element 12 upon removal of the latter.

[0011] Referring to Figure 2, there is shown a modified shape of re-usable masking element 22 fitted to one end of the heat-shrinkable tubular component 10. Element 22 is in the form of a cap having inner and outer circumferential skirts 23,24 which are spaced apart to receive an end por­tion of the component 10 therebetween. The annular space between the two skirts 23,24 is slightly less than the wall thickness of the component 10, so that the latter will be compressed slightly against its own inherent resilience and therefore the skirts 23,24 press firmly against the inner and outer surfaces of the component 10. This again provides for effective masking of the areas concerned.

[0012] Referring to Figure 3, there is shown a re-usable masking element in the form of a flexible or semi-flexible tubular member 32 of outer diameter greater than the inner diameter of the tubular component 10. The masking element is inserted into the component 10 by folding or kinking it along its length as shown, then pushing it into one end of the component 10 and releasing it. The element 32 then expands radially under its own resilience, as far as the inner diameter of the component 10 will allow. The masking element thus presses firmly against the inner surface of the component 10 over a substantial portion of the cir­cumference of the latter.

[0013] It will be appreciated that each of the masking elements which have been described can be removed readily from the tubular component, after the required surface treatment of the unmasked area(s) has been carried out. The masking elements can then be re-used.

[0014] It will also be appreciated that the tubular component which is masked may be of any desired cross-­sectional shape (e.g. circular, square, elliptical etc) and its cross-sectional shape and/or size may vary along its length. The masking element may also be of any desired cross-sectional shape and may similarly vary in cross-sectional shape and/or size along its length.

Claims

1) A method of masking a selected area or selected areas of a tubular component prior to treating unmasked surface areas, comprising fitting a re-usable masking element to the tubular component, the tubular component and/or the masking element resiliently deforming so as to be urged together over the selected area or areas of the tubular component.

2) A method as claimed in claim 1, in which the tubular component comprises a heat-shrinkable tubular component of plastics material.

3) A method as claimed in claim 1 or 2, in which the re-usable masking element comprises a tubular member which is fitted within one end of the tubular component to mask an area of the inside surface adjacent that end.

4) A method as claimed in claim 3, in which the tubular masking member is chamfered around its inner edge at one end thereof.

5) A method as claimed in claim 1 or 2, in which the re-usable masking element comprises a tubular member which is fitted around the outside of the tubular component to mask an area of its outer surface.

6) A method as claimed in claim 5, in which the tubular masking member comprises a cap which is fitted to an end of the tubular component, the cap having an outer circumferential skirt which fits against the outer surface of the tubular component.

7) A method as claimed in claim 1 or 2, in which the re-usable masking element comprises a flexible or semi-­flexible tubular member of resilient material of outer diameter greater than the inner diameter of the tubular component the masking element being fitted by first being folded and kinked along its length then being injected into the tubular component and allowed to expand under is own resilience and press firmly against the inner surface of the tubular component over a portion of its circumference.

8) A method of forming a tubular component with a selected area or selected areas of its surface treated, comprising taking a tubular component, masking a selected area or selected areas thereof using a method as claimed in any preceding claim, subjecting unmasked areas of the tubular component to a surface treatment, and then removing the masking element for re-use.

Drawing