This invention relates generally to an insert and more specifically, although not exclusively, to an insert with retaining features such as projections on its outer surface for insertion or incorporation into a moulded part. More particularly, this invention relates to a method of manufacturing such an insert as well as the insert itself.

Inserts for incorporation into moulded parts, particularly those formed of a plastics material, are known. Such inserts may be required to provide, for example, regions of higher strength or durability. This invention is particularly concerned with inserts formed of metal for incorporation into plastic parts for creep mitigation and/or compression limitation.

Anti-creep inserts or spacers, also known as compression limiters, are often used to provide reinforced clearance holes for bolts to pass through a plastic moulding. These inserts allow relatively high metal-to-metal clamping forces to be applied to an assembly without stressing the plastic beyond its elastic limit. The insert must also be sized and dimensioned to limit the clamping forces applied to the plastic regions in order to prevent creep of the plastic over time, which would reduce the overall clamping force and allow the bolt to loosen, for example under vibration.

These inserts may be moulded-in or inserted after the moulding operation. Examples of such inserts include split seam designs for post-moulding insertion, solid designs with a knurled outer surface either for in-mould or over-mould manufacture or for post-mould insertion and designs with radial grooves on their outer surface for in-mould manufacture. The inserts are generally formed of a brass or steel (e.g. carbon steel) material, depending upon the application. When formed of heat treated steel, de-embrittlement and/or other heat treatment processes are generally required, which adds significant cost to the manufacturing of such inserts. The majority of these inserts are also machined, which is expensive and creates a great deal of material waste.

It is therefore a non-exclusive object of the invention to provide an insert and/or a method of manufacturing an insert that mitigates the aforementioned issues associated with known designs.

One aspect of the invention provides a method of making an insert, e.g. for a moulded part, the method comprising the steps of providing a length or strip of material, forming a depression on a first side of the length or strip of material in order to create a projection on a second side opposite the first side and forming the length or strip of material into a ring or tube or sleeve such that its ends abut one another.

This method enables anti-creep spacers to be manufactured from less expensive materials, in many cases without the need for post forming operations, heat treatment and the like.

The ring or tube or sleeve forming step preferably comprises forming the length or strip of material such that the projection is external, for example radially external or extends externally or radially externally and/or such that the depression is internal for example radially internal. The depression forming step preferably comprises punching the depression into the first side, for example a round or square depression or a depression of any other requisite or suitable shape, preferably using a punch having an end with a substantially squared axial cross-section, for example a flat end with a side or sides substantially orthogonal or perpendicular thereto, e.g. between 80 and 100 degrees or 85 and 95 degrees or 90 and 100 degrees or 90 and 95 degrees or substantially 90 degrees. The depression forming step may comprise two or more depressions, for example three or more depressions, e.g. four or more depressions, on the first side of the length or strip of material, e.g. in order to create corresponding projections.

The method preferably comprises retaining the length or strip, for example transversely, e.g. a third and/or fourth sides that may be perpendicular to the first and/or second sides, such as to prevent side load. The method may also comprise retaining the length or strip along the first and/or second sides, for example using a stripper plate, e.g. to enable retraction of the former or punch. One or more of the forming steps may be carried out using a four slide machine.

The length or strip of material is preferably substantially flat and/or has a substantially square or rectangular cross-section that more preferably includes rounded corners or edges. The length or strip of material may comprise a strip, bar or wire of material, e.g. that is supplied in coil form. The method may further comprise cutting the strip from the coil, e.g. prior to the sleeve forming step. The length or strip of material may comprise a metal, for example a steel such as a mild steel, or brass or any other suitable material.

In a particularly preferred embodiment of the invention, the method comprises coining or compressing, e.g. plastically compressing, the length or strip of material or sleeve or insert such that the width of the length or strip of material or the length of the sleeve or insert is reduced, for example without substantially altering, or minimising any change to, the thickness of the length or strip of material and/or without substantially altering, or minimising any changes to, an inner or outer diameter of the sleeve or insert. The coining step may also be used to improve and/or reduce the tolerance in the width of the length or strip of material and/or in the length of the manufactured insert. In a most preferred embodiment, the rounded corners or edges of the length or strip of material comprise a radius that is configured to permit the strip or insert to be compressed, e.g. plastically compressed, without altering the thickness of the length or strip of material and/or without altering an inner or outer diameter of the sleeve or insert.

A second aspect of the invention provides a method of manufacturing a component that includes an insert, the method comprising the steps of providing a length or strip of material, forming a depression on a first side of the length or strip of material in order to create a projection on a second side opposite the first side, forming the length or strip of material into a ring or tube or sleeve such that its ends abut one another and inserting the insert into a component, for example a moulded component that may be moulded from a plastics material.

A third aspect of the invention provides a method of manufacturing a component that includes an insert, the method comprising the steps of providing a length or strip of material, forming a depression on a first side of the length or strip of material in order to create a projection on a second side opposite the first side, forming the length or strip of material into a ring or tube or sleeve such that its ends abut one another and inserting the insert into a mould, for example a plastics and/or injection or compression or thermoforming mould, and preferably moulding a component around a portion of the insert.

One or more of the methods described above may further comprise case hardening and/or heat treatment and/or de-embrittlement of the insert prior to its incorporation into the or a component.

A fourth aspect of the invention provides an insert, e.g. for a moulded part, that may have been made using a method as described above and/or may comprise a ring or tube or sleeve that may be formed from a length or strip of material whose ends meet at a butt joint. The insert may comprise one or more, for example two or more, e.g. three or more, e.g. four or more, depressions on an internal, e.g. radially internal, side or surface thereof and/or one or more, for example two or more, e.g. three or more, e.g. four or more, projections or corresponding projections on an external, e.g. radially external, side or surface thereof, which projection or projections may comprise material displaced by the formation of the depression or a corresponding one of the depressions.

The depression may comprise a punched depression and may be round or square or any other suitable shape in plan. The depression may comprise a substantially squared axial cross-section, for example a flat base with a side or sides substantially orthogonal or perpendicular, e.g. between 80 and 100 degrees or 85 and 95 degrees or 90 and 100 degrees or 90 and 95 degrees or substantially 90 degrees. The or each depression is preferably located at substantially the centre of the length of the ring or tube or sleeve. Where there are two or more depressions, they are preferably spaced equally about the internal circumference of the ring or tube or sleeve.

The projection may comprise dimples, for example the shape of each projection may correspond to or be determined by or result from, the shape of the corresponding depression, e.g. the projection may comprise a bulge in the material that results from the formation of the depression. In some embodiments, the projection comprises a gradual and/or rounded profile to enable insertion post-moulding.

The ring or tube or sleeve or length or strip of material may comprise a substantially square or rectangular cross-section that may include rounded corners or edges. The length or strip of material may comprise a strip, bar or wire of material, e.g. that is supplied in coil form. The ring or tube or sleeve or length or strip of material may be coined, e.g. wherein the rounded corners or edges of the length or strip of material comprise a radius that is configured to permit the strip or insert to be coined or compressed, e.g. plastically compressed, without altering the thickness of the length or strip of material and/or without altering an inner or outer diameter of the sleeve or insert.

The insert may comprise a metal, for example a steel such as a mild steel, or brass or any other suitable material.

A fifth aspect of the invention provides a component that includes an insert as described above and/or made using a method as described above. The component may be a moulded component and/or the insert may be push fit into a depression or hole or aperture or receptacle in or of the component. The component may be a moulded component that comprise a plastics material, in which case the insert may either be push fit as described above or over-moulded, for example such that it is at least partially embedded within the component or within the or a depression or hole or aperture or receptacle in or of the component.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a perspective view of an insert according to a first embodiment of the invention;

Figure 2 illustrates the punching of a depression to form one of the projections of the embodiment of Figure 1 ;

Figure 3 is a perspective view of an insert according to a second embodiment of the invention;

Figure 4 illustrates the punching of a depression to form one of the projections of the embodiment of Figure 3;

Figure 5 is a perspective view of an insert according to a third embodiment of the invention;

Figure 6 illustrates the punching of a depression to form one of the projections of the embodiment of Figure 5;

Figure 7 is a plan view of an insert according to a fourth embodiment of the invention; and

Figure 8 is a figurative view illustrating the way in which the insert deforms during coining.

Referring to Figures 1 and 2, there is shown an insert 1 according to a first embodiment of the invention for insertion into a moulded part (not shown). The insert 1 is in the form of a sleeve 2 formed from a length or strip of material whose ends meet at a butt joint 3. The insert 1 includes three depressions 4 on a radially internal surface 20 of the sleeve 2 and three corresponding projections 5 on a radially external surface 21 thereof. The sleeve 2 has a length L-i and a wall thickness T-i . Each depression 4 is round in plan and has a squared axial cross-section with a flat base 40 and a circumferential side 41 that is orthogonal to the base 40. Each depression 4 is located substantially at the centre of the length L-i of the sleeve 2 and the depressions 4 are spaced equally about the internal circumference 20 of the sleeve 2.

Each projection 5 is in the form of a dimple or bulge 5 in the material opposite one of the depressions 4 and includes a gradual or rounded profile to enable insertion of the insert 1 into a component (not shown) after it has been moulded.

In this embodiment, the insert 1 is formed of a mild steel, but it may also be formed of brass or any other suitable material. The insert 1 has a substantially square or rectangular axial cross-section with rounded corner edges.

To make the insert 1 , a coil of material (not shown) supplies a length of material 6 into a guide (not shown) that restrains the transverse sides 60 of the length of material 6 while a stripper plate (not shown) is put into contact with the top surface 20 of the length of material 6 to retain it against a substrate (not shown). One or more punches 7 are then used to punch the depressions 4 into the length of material 6, a strip 8 is then cut from the coil and formed into the sleeve 2.

The or each punch 7 has an end with a substantially squared axial cross-section with a flat end 70 and a substantially orthogonal or perpendicular side 71. This design was found to be particularly advantageous because the deformation of the transverse sides 60 during the punching operation is minimal as compared to punches with a rounded or chamfered axial cross-section.

In some embodiments, the substrate (not shown) is provided with a recess or depression to accommodate and/or at least partially constrain the formation of the projection 5.

Figures 3 and 4 show an insert 100 according to a second embodiment of the invention, while Figures 5 and 6 show an insert 200 according to a third embodiment of the invention. The inserts 100, 200 according to the second and third embodiment are similar to the insert 1 according to the first embodiment, wherein like references depict like features that will not be described further. The inserts 100, 200 according to the second and third embodiments differ from that of the first embodiment only in their cross-sectional sizes L ₂ , T ₂ and L ₃ , T ₃ . Figure 7 shows an insert 300 according to a fourth embodiment of the invention, which is similar to the inserts 1 , 100, 200 according to the first three embodiments, wherein like references depict like features that will not be described further. The insert 300 according to this embodiment differs from the insert of the third embodiment in that it includes four projections 5 rather than three.

As shown in Figure 8, the inserts 1 , 100, 200, 300 according to the embodiments described above may be coined or compressed plastically in the axial direction in order to produce a predetermined and accurate insert length L-i , L ₂ , L ₃ . This may be done during the forming process described above, but is preferably carried out after the insert 1 , 100, 200, 300 has been formed into the sleeve 2.

The rounded corner edges of the insert 1 , 100, 200, 300 have a pre-coined radius Ri that is configured such that coining of the insert 1 , 100, 200, 300 does not alter the wall thickness Ti, T ₂ , T ₃ of the insert 1 , 100, 200, 300. Instead, compression displaces the material such that the radii Ri are reduced to a post-coined radius R ₂ .

It will be appreciated by those skilled in the art that several variations are envisaged without departing from the scope of the invention. For example, the insert 1 , 100, 200, 300 may be inserted into a component after the moulding process or it may be inserted into the cavity of a mould prior to the moulding process such that the component is moulded around at least part of the insert 1 , 100, 200, 300. The insert and method may be used with or for components formed of a thermoset or thermoplastic moulding.

It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.