GB2026448A

GB2026448A - Dismountable seal arrangements

Info

Publication number: GB2026448A
Application number: GB7918955A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-31
Filing date: 1979-05-31
Publication date: 1980-02-06
Also published as: GB2026448B; NO145671B; NO145671C; NO781888L

Abstract

A moulded plastics lid (2) and a moulded plastics base (3) of a container (1) are releasably secured together by means of screws (4), Figure 1 (not shown). The joint between the lid (2) and base (3) is sealed by a gasket (16) accommodated, as shown, in grooves (5) and (13) moulded into facing surfaces of the lid and base. The gasket (16) is compressed between surfaces defined by the side walls (7, 8; 13, 14) of the grooves (5; 13), each of which surfaces extends substantially parallel to the direction of withdrawal of the moulding tool used in manufacture of the respective component. <IMAGE>

Description

SPECIFICATION Dismountable seal arrangements This invention relates to dismountable seal arrangements. More particularly, but not exclusively, the invention relates to reuseable dismountable seal arrangements for containers, in particular plastics containers.

It has been found to be difficult and expensive to obtain a satisfactory seal at high pressures for moulded plastics designs when the seal has to be dismountable. When an ordinary gasket or an O-ring is used, the load on the gasket must be as even as possible. As a result, undesirably large material dimensions and/or an undesirably large number of fixing screws must be used to ensure the stability of the joint.

According to the present invention there is provided a dismountable seal arrangement comprising moulded components which may be assembled together and disassembled and at least one sealing element that co-operates with the moulded components to seal them when they are assembled together, wherein the sealing element is compressed, when the components are assembled, between surfaces of the components, each of which surfaces was formed on moulding of the component and extends substantially parallel to the direction of withdrawal of the moulding tool used in manufacture of the component.

A seal arrangement embodying the present invention and described hereinbelow provides the necessary even load on the sealing member or gasket, whilst maintaining the dimensions of the material used and the number of fixing screws relatively small.

The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawing, wherein: Figure 1 shows a container that may embody a seal arrangement in accordance with the invention; Figure 2 is a section showing a prior art seal arrangement; and Figure 3 is a section through an embodiment of the invention.

Figure 1 shows a container 1 comprising a moulded plastics lid 2 and a moulded plastics base or body 3. The lid 2 is clamped to the base 3 using one or more screws 4. When the joint between the lid 2 and the base 3 must be sealed, for instance so as to be gastight up to 200 mbars, it is necessary and usual to use a gasket.

An example of a conventional seal is drawn in Figure 2. In the base 3 there is moulded a groove 5 which accommodates an elastically deformable 0ring 6. The diameter of the O-ring 6 is somewhat larger than the height b of the side walls 7 and 8 of the groove 5. The lid 2 has a flat underside 9 which presses against the O-ring 6 when the lid is fitted to the base 3. The O-ring 6 is compressed by its being squeezed between a top surface 10 and a bottom surface 11 thereof.

Due to the limited stiffness of plastics materials, it may be difficult to make such a seal sufficiently tight at the high excess pressures occuring in certain environments without resort to solutions incorporating particularly large dimensions. The problem of obtaining a good seal is further exacerbated by the plastics material of the base 3 settling during the moulding process, such that the bottom 12 of the groove 5 becomes uneven when the moulding tool is withdrawn. Furthermore, sealing becomes more complicated when the container 1 does not have a circular cross section, but is rectanguiar, elliptical or of an even more complex shape.

A dismountable seal arrangement embodying the invention is shown in Figure 3. The seal arrangement includes a groove 5 moulded in the base 3 of the container 1 and a corresponding groove 13 moulded in the lid 2. The groove 13 has side walls 14 and 15.

The seal arrangement also includes an elastically deformable gasket 16 fitted into the grooves 5 and 13 and designed in such a way that its width is greater than the distance a between the side walls 7,8 and 14,15, whereby it is compressed between the side walls 7 and 8 and between the side walls 14 and 15.

At least one surface part of the walls 7 or 8 and one surface part of the walls 14 or 15 engage the gasket 16 to form a seal. The gasket 16 preferably has a figure-of-eight cross section, as shown. This provides a dual or double set of sealing surfaces, an effect which may, however, also be obtained by using other cross sectional profiles.

An important advantage of the seal arrangement shown in Figure 3 is that the gasket 16 is being compressed or squeezed between two surfaces (7, 8; 14,15} which are parallel or largely parallel to the direction of withdrawal of the moulding tool used in the manufacture of the component (2, 3) bearing the surfaces. The moulding tool, which usually comprises an outer and an inner mould, is separated by pulling the moulds apart. It has been found that one may obtain far better dimensional stability across the direction of withdrawing the tool than along it, where one is likely to get settling of the material so that the surfaces become uneven.

The seal arrangement of Figure 3 is reliable and reproduceable and may be assembled and disassembled, and re-used, without problems.

1. A dismountable seal arrangement comprising moulded components which may be assembled together and disassembled and at least one sealing element that co-operates with the moulded components to seal them when they are assembled together, wherein the sealing element is compressed, when the components are assembled, between surfaces of the components, each of which surfaces was formed on moulding of the component and extends substantially parallel to the direction of withdrawal of the moulding tool used in manufacture of the component.

2. A seal arrangement according to claim 1, wherein the moulded components are moulded plastics components.

3. A seal arrangement according to claim 1 or claim 2, wherein the moulded components co

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Dismountable seal arrangements This invention relates to dismountable seal arrangements. More particularly, but not exclusively, the invention relates to reuseable dismountable seal arrangements for containers, in particular plastics containers. It has been found to be difficult and expensive to obtain a satisfactory seal at high pressures for moulded plastics designs when the seal has to be dismountable. When an ordinary gasket or an O-ring is used, the load on the gasket must be as even as possible. As a result, undesirably large material dimensions and/or an undesirably large number of fixing screws must be used to ensure the stability of the joint. According to the present invention there is provided a dismountable seal arrangement comprising moulded components which may be assembled together and disassembled and at least one sealing element that co-operates with the moulded components to seal them when they are assembled together, wherein the sealing element is compressed, when the components are assembled, between surfaces of the components, each of which surfaces was formed on moulding of the component and extends substantially parallel to the direction of withdrawal of the moulding tool used in manufacture of the component. A seal arrangement embodying the present invention and described hereinbelow provides the necessary even load on the sealing member or gasket, whilst maintaining the dimensions of the material used and the number of fixing screws relatively small. The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawing, wherein: Figure 1 shows a container that may embody a seal arrangement in accordance with the invention; Figure 2 is a section showing a prior art seal arrangement; and Figure 3 is a section through an embodiment of the invention. Figure 1 shows a container 1 comprising a moulded plastics lid 2 and a moulded plastics base or body 3. The lid 2 is clamped to the base 3 using one or more screws 4. When the joint between the lid 2 and the base 3 must be sealed, for instance so as to be gastight up to 200 mbars, it is necessary and usual to use a gasket. An example of a conventional seal is drawn in Figure 2. In the base 3 there is moulded a groove 5 which accommodates an elastically deformable 0ring 6. The diameter of the O-ring 6 is somewhat larger than the height b of the side walls 7 and 8 of the groove 5. The lid 2 has a flat underside 9 which presses against the O-ring 6 when the lid is fitted to the base 3. The O-ring 6 is compressed by its being squeezed between a top surface 10 and a bottom surface 11 thereof. Due to the limited stiffness of plastics materials, it may be difficult to make such a seal sufficiently tight at the high excess pressures occuring in certain environments without resort to solutions incorporating particularly large dimensions. The problem of obtaining a good seal is further exacerbated by the plastics material of the base 3 settling during the moulding process, such that the bottom 12 of the groove 5 becomes uneven when the moulding tool is withdrawn. Furthermore, sealing becomes more complicated when the container 1 does not have a circular cross section, but is rectanguiar, elliptical or of an even more complex shape. A dismountable seal arrangement embodying the invention is shown in Figure 3. The seal arrangement includes a groove 5 moulded in the base 3 of the container 1 and a corresponding groove 13 moulded in the lid 2. The groove 13 has side walls 14 and 15. The seal arrangement also includes an elastically deformable gasket 16 fitted into the grooves 5 and 13 and designed in such a way that its width is greater than the distance a between the side walls 7,8 and 14,15, whereby it is compressed between the side walls 7 and 8 and between the side walls 14 and 15. At least one surface part of the walls 7 or 8 and one surface part of the walls 14 or 15 engage the gasket 16 to form a seal. The gasket 16 preferably has a figure-of-eight cross section, as shown. This provides a dual or double set of sealing surfaces, an effect which may, however, also be obtained by using other cross sectional profiles. An important advantage of the seal arrangement shown in Figure 3 is that the gasket 16 is being compressed or squeezed between two surfaces (7, 8; 14,15} which are parallel or largely parallel to the direction of withdrawal of the moulding tool used in the manufacture of the component (2, 3) bearing the surfaces. The moulding tool, which usually comprises an outer and an inner mould, is separated by pulling the moulds apart. It has been found that one may obtain far better dimensional stability across the direction of withdrawing the tool than along it, where one is likely to get settling of the material so that the surfaces become uneven. The seal arrangement of Figure 3 is reliable and reproduceable and may be assembled and disassembled, and re-used, without problems. CLAIMS

3. A seal arrangement according to claim 1 or claim 2, wherein the moulded components co operate when assembled together to form a container.

4. A seal arrangement according to claim 1, claim 2 o, claim 3, wherein the sealing element is elastically deformable.

5. A seal arrangement according to any one of the preceding claims, wherein the sealing element has a dual set of sealing surfaces.

6. A seal arrangement according to any one of the preceding claims, wherein the sealing element has a cross-section at least approximately like a figure-of-eight.

7. A dismountable seal arrangement substantially as herein described with reference to the accompanying drawing.