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Patent Searching and Data


Title:
AN INSERT AND METHOD OF MANUFACTURING AN INSERT
Document Type and Number:
WIPO Patent Application WO/2009/150390
Kind Code:
A1
Abstract:
An insert (100) has an internal threaded bore (130) comprising a locking feature (142, 146) proximate and end (106) farthest from a surface (12) of a plastics component (10) in which the insert is installed. An insert (100) having a pair of axially spaced thread locking deformations (140, 142). An insert (400) with a thread (404) defining a taper (406).

Inventors:
MARTIN PAUL (GB)
Application Number:
PCT/GB2008/002012
Publication Date:
December 17, 2009
Filing Date:
June 12, 2008
Export Citation:
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Assignee:
PSM IP LTD
MARTIN PAUL (GB)
International Classes:
F16B37/12; F16B39/284
Foreign References:
GB1497693A1978-01-12
EP0527627A11993-02-17
US3220029A1965-11-30
FR2640705A11990-06-22
GB985714A1965-03-10
Attorney, Agent or Firm:
CROSTON, David (Goldings House2 Hays Lane, London SE1 2HW, GB)
Download PDF:
Claims:

Claims

1. An insert for installation into a plastics component comprising a generally cylindrical body having a bore defining an internal thread, the internal thread having a first end arranged to be positioned towards a surface of a plastics component when the insert is installed and a second end arranged to be positioned away from the surface, wherein the insert comprises a first locally deformed section configured to deform the internal thread at an axial position along the internal thread and wherein the insert comprises a second locally deformed section configured to deform the internal thread at an axial position spaced from the first locally deformed section.

2. An insert according to claim 1 in which the first locally deformed section is positioned along the internal thread proximate the second end.

3. An insert for installation into a plastics component comprising a generally cylindrical body having a bore defining an internal thread, the internal thread having a first end arranged to be positioned towards a surface of a plastics component when the insert is installed and a second end arranged to be positioned away from the surface, wherein the insert comprises a first locally deformed section configured to deform the internal thread at an axial position along the internal thread proximate the second end to form a thread locking feature.

4. An insert according to claim 1 or 2 in which the first locally deformed section comprises a run-in and the second locally deformed section comprises a run-out, wherein the end of the run-out is proximate the start of the run-in.

5. An insert according to claim 1 or 2 in which the first locally deformed section comprises a run-in and the second locally deformed section comprises a run-out, wherein the run-in and the run-out are at least partially coincident.

6. An insert according to any of claims 1, 2, 4 or 5 in which the second locally deformed section is positioned at an axial position along the internal thread closer to the first end that the second end.

7. An insert according to any preceding claim in which at least one of the locally deformed sections is a crimped section.

8. An insert according claim 7 in which the crimped section comprises two substantially opposite circumferential deformations.

9. An insert according to any preceding claim comprising a first and a second cylindrical portion separated by a first circumferential groove, the second cylindrical portion being positioned proximate the second end, and in which the first locally deformed section is coincident with the second cylindrical portion.

10. An insert according to claim 9 further comprising a third cylindrical portion proximate the first end, the third cylindrical portion being separated from the second cylindrical portion by a second circumferential groove, in which the second locally deformed section is coincident with the second groove.

11. An insert according to any preceding claim comprising ribs or knurls at least partially covering an outer surface of the insert.

12. An insert according to any preceding claim in which the insert comprises a first end first end arranged to be positioned proximate a surface of a plastics component when the insert is installed and a second end arranged to be positioned away from the surface in which the first locally deformed section is proximate the second end of the insert.

13. An insert according to any preceding claim in which the insert comprises a stop means arranged to inhibit further movement of a male threaded member further into the insert, and in which the first locally deformed section is proximate the stop means.

14. An insert for installation into a plasties component comprising a generally cylindrical body having a bore defining an internal thread, wherein the thread defines an inwardly tapered region to form a tapered thread locking feature.

15. An insert for installation into a mobile telephone component, the insert according to any preceding claim.

16. An insert for installation into a notebook computer, the insert according to any of claims 1 to 14.

17. A method of manufacturing an insert comprising the steps of: providing a generally cylindrical insert having a bore defining a threaded portion, the threaded portion having a first end and a second end, externally locally deforming the insert to deform a first section of the threaded portion, externally locally deforming the insert to deform a second section of the threaded portion axially spaced from the first section, installing the insert into a plastics component with the bore exposed to a surface of the plastics component.

18. A method of manufacturing an insert comprising the steps of: providing a generally cylindrical insert having a bore defining a threaded portion, the threaded portion having a first end and a second end, externally locally deforming the insert to deform a first section of the threaded portion proximate the second end to form a first thread locking feature proximate the second end, installing the insert into a plastics component with the bore exposed to a surface of the plastics component and the first end of the threaded bore closer to the surface than the second end.

19. A method of manufacturing according to claim 17 comprising the further step of:

externally locally deforming the insert to deform a second section of the threaded portion to form a second thread locking feature axially spaced from the first thread locking feature.

20. A method of manufacturing according to claim 19 in which the second thread locking feature is formed at an axial position along the internal thread closer to the first end that the second end.

21. A method of manufacturing according to any of claims 17, 19 or 20 in which the first section and the second sections are deformed simultaneously.

22. A method of manufacturing according to any of claims 17 to 21 in which the of the steps of externally locally deforming comprise the step of crimping.

23. A method of manufacturing according to claim 22 in which the step of crimping forms comprises two substantially opposite circumferential deformations.

24. A method of manufacturing according to any of claims 17 to 23 comprising the further step of forming ribs or knurls at least partially covering an outer surface of the insert.

25. A method of installing an insert into a plastics notebook computer component or plastics mobile telephone component comprising the steps of: providing a plastics notebook computer component or plastics mobile telephone component, providing an insert according to any of claims 1 to 16, installing the insert in the notebook computer component or mobile telephone component.

Description:

An insert and method of manufacturing an insert

The present invention relates to an insert for installation into a plastics material component. Specifically, the present invention relates to threaded inserts for installation into plastics material components such as automotive components, notebook computers and mobile phone casings for the attachment of further threaded components. The present invention also relates to a method of manufacturing such inserts.

Plastics materials are generally poor at holding formations for mechanical connections such as threads. Low stiffness and strength means that conventional threads formed in such plastics materials will tend to fail easily.

It is desirable to use mechanical connections such as threads with plastics components in order to attach further components to them by threaded members such as bolts.

One solution to this problem is to provide a metal insert defining an internally threaded bore. The insert also defines features on its external periphery to mechanically engage with the plastics material.

Such inserts are commonly installed into plastics material components by heating the component (either by heating the insert or ultrasonically vibrating the insert) and urging the insert into the molten plastics material. The molten material then flows around the features on the external periphery of the insert and cools and hardens to retain the insert in position.

The inserts are installed such that the threaded bore faces outwards and as such a threaded male component (such as a bolt) can be easily attached to the insert, and hence the plastic component.

A further problem is that mechanical attachment of components via threads is often unreliable as vibrations and movement of products featuring such threads in use can case loosening and eventual unfastening of the threaded connection.

Various thread locking technologies are known to address this problem. For example the male member is sometimes coated in a plastics material to cause the male and female threads to grip in use and take up any loose movement between the components which may encourage loosening.

Alternatively, the female thread may be plastically deformed from an undeformed state into a deformed state during manufacture of the insert. This forms a thread locking feature in the female thread. In order to mate with the female thread, the male thread must therefore deform the female thread back to the undeformed state. This deformation to the undeformed state is at least part elastic in nature and the resulting resilient tendency for the female thread to return to the deformed state applies a restoring force onto the male thread which lessens the loosening effect.

Such thread locking features are positioned midway along the length of the insert as they are intended to be effective if either the male member is too short to extend all the way along the insert.

A problem with this type of thread lock is that as the male thread progresses through the female thread, the female thread gradually plastically deforms, removing the thread locking feature and reducing the effectiveness of the thread lock. This thread lock removing plastic deformation occurs as male threads are often not perfectly helical in shape and as such the deformation of the female thread varies throughout the progression of the male threaded member.

The thread locking torque can also be affected by thread form variations along the length of the male member. It is common for screws to have a slight taper at the front and at back of thread and variations in diameter and pitch are also common.

Users of this type of product desire to retain a predetermined minimum level of torque to remove the male member following a number of repeat reinsertions. The thread lock also becomes less effective when multiple insertions and removals take place. This further increases the amount of plastic deformation which reduces the effectiveness of the thread lock.

It is an aim of the present invention to provide an improved insert and / or to overcome, or at least mitigate one of the above problems.

According to a first aspect of the invention there is provided an insert for installation into a plastics component comprising a generally cylindrical body having a bore defining an internal thread, the thread having a first end arranged to be positioned towards a surface of a plastics component when the insert is installed and a second end arranged to be positioned away from the surface, wherein the insert comprises a first locally deformed section configured to deform the internal thread at an axial position along the internal thread and wherein the insert comprises a second locally deformed section configured to deform the internal thread at an axial position spaced from the first locally deformed section.

According to a second aspect of the invention there is provided an insert for installation into a plastics component comprising a generally cylindrical body having a bore defining an internal thread, the internal thread having a first end arranged to be positioned towards a surface of a plastics component when the insert is installed and a second end arranged to be positioned away from the surface, wherein the insert comprises a first locally deformed section configured to deform the internal thread at an axial position along the internal thread proximate the second end to form a thread locking feature.

According to a third aspect of the invention there is provided an insert for installation into a plastics component comprising a generally cylindrical body having a bore defining an internal thread, wherein the internal thread defines an inwardly tapered region to form a tapered thread locking feature.

According to a fourth aspect of the invention there is provided a method of manufacturing an insert comprising the steps of: providing a generally cylindrical insert having a bore defining a threaded portion, the threaded portion having a first end and a second end, externally locally deforming the insert to deform a first section of the threaded portion, externally locally deforming the insert to deform a second section of the threaded portion axially spaced from the first section, installing the insert into a plastics component with the bore exposed to a surface of the plastics component.

According to a fifth aspect of the invention there is provided a method of manufacturing an insert comprising the steps of: providing a generally cylindrical insert having a bore defining a threaded portion, the threaded portion having a first end and a second end, externally locally deforming the insert to deform a first section of the threaded portion proximate the second end to form a first thread locking feature proximate the second end, installing the insert into a plastics component with the bore exposed to a surface of the plastics component and the first end of the threaded bore closer to the surface than the second end.

Advantageously, positioning the thread locking feature proximate the second end of the internal thread provides that the male threaded member only engages it for sufficient distance for it to begin to grip the male threaded member. The continuous and repetitive engagement which is caused by the thread locking feature being positioned further towards the surface is therefore avoided.

An example insert and method of manufacture will now be described with reference to the accompanying figures in which:

Figure 1 is a side view of a first insert in accordance with the present invention,

Figure 2 is a side section view of the insert of figure 1 along line II-II in an installed configuration,

Figures 3 a to 3 c are side section views of the insert of figure 1 in use, Figures 4a to 4c are side section views of a part of manufacturing process for manufacturing the insert of figure 1,

Figures 5 a and 5b are side section views of a second insert in accordance with the present invention, and

Figures 6a and 6b are side section views of a part of a third insert in accordance with the present invention.

Figure 1 shows an insert 100. The insert 100 is substantially cylindrical, and substantially axially symmetric about a main axis 102. The insert 100 defines a first end 104 and a second end 106.

Proximate the first end 104 is a first cylindrical section 108. The first cylindrical section 108 defines a plurality of helical grooves 110 on its outer surface.

A second cylindrical section 112 is defined approximately midway between the first end 104 and the second end 106. The second cylindrical section 112 defines a plurality of helical grooves 114, oppositely oriented to the helical grooves 110 on the first cylindrical section 108. The second cylindrical section 112 defines a tapered region 116 which tapers inwardly towards the second end 106.

A first annular groove 118 is defined between the first cylindrical section 108 and the second cylindrical section 112. The first annular groove 118 defines a crimped region 120.

A third cylindrical section 122 is defined proximate the second end 106 of the insert 100. The third cylindrical section 122 defines a tapered region 124 which tapers inwardly to the second end 106. The third cylindrical section 122 is separated from the second cylindrical section by a second annular groove 126.

The third cylindrical section 122 defines a crimped region 128.

Referring to figure 2, the insert 100 is installed in a plastics component 10. The plastics component 10 has an outer surface 12. The insert 100 is installed such that the first end 104 is proximate the surface 12.

As can be seen in figure 2, the insert 100 comprises an internal open bore 130, coaxial with the axis 102. The bore 130 defines a thread 132 along its entire length.

The insert 100, as can bee see in figure 2, comprises further crimped regions 134, 136 substantially opposite the crimped regions 120, 128 respectively. It may also be seen that at each of the crimped regions 120, 128, 134, 136, the thread 132 has corresponding deformed regions 140, 142, 144, 146 respectively.

In particular, the deformed regions 142, 146 are proximate the second end 106 of the insert 100.

Referring now to figures 3a to 3c, a male threaded member 148 is shown comprising an external thread 150. The male threaded member 148 is typically a bolt for the attachment of a further component (not shown) such as corresponding component for the plastics component 10.

The external thread 150 corresponds to the internal thread 132 of the insert 100.

The male threaded member 148 is rotated clockwise to engage the threads 150, 132. As the male threaded member progresses, the thread 150 encounters the deformed regions 140, 144 of the thread 132. As this occurs, additional force must be applied by the user to turn the member 148 and use the external thread 150 to attempt to return the deformed regions 140, 144 to an undeformed condition.

The inherent elasticity of the metal material of the insert 100 resiliently urges the deformed regions 140, 144 back to their deformed state, and in doing so clamps the male threaded member. In this way a "thread lock" feature is provided.

As the male threaded member 150 progresses through the bore 130, the deformed regions 140, 144 slowly become significantly plastically deformed towards their undeformed state. This is caused by variations in the geometry of the male thread 150 causing repetitive loading on the female thread 132 as well as movement of the male member 150 during insertion by the user.

As the male member 148 progresses through the position shown in figure 3b and to the position shown in figure 3c, the thread 150 begins to engage the deformed portions 142, 146 proximate the second end 106 of the insert 100.

Shortly after dong so, the male member 148 reaches its final position as shown in figure 3c in which it cannot be inserted any further (due to its length). The thread 150 has only just engaged the deformed regions 142, 146 and as such has the aforementioned significant plastic deformation has not had the opportunity to occur. Rather the deformed portions 142, 146 present their maximum possible elastic deformation and clamp the male member 148 to provide a more secure thread locking effect than the deformed regions 140, 144.

Figures 4a to 4c show a method of manufacture of the insert 100. One half of an internally threaded insert workpiece 200 is shown in figure 4a. The workpiece 200 defines the portions 108, 112, 122 of the insert 100 as well as the bore 130 and the internal thread 132. The workpiece 200 is normally turned from a solid piece of metal.

In figure 4b a first crimping tool 202 is used to form the crimped portion 120. As the crimped portion 120 is formed, the internal thread 132 is deformed to produce the deformed region 140.

In figure 4c a second crimping tool 204 is used to form the crimped portion 128. As the crimped portion 128 is formed, the internal thread 132 is deformed to produce the deformed region 142. As the opposite operations are performed at the same time on the opposite side of the workpiece 200, the insert 100 is formed.

Referring to figures 5a and 5b, an insert 300 is shown installed in a plastics component 20. The insert 300 is substantially similar to the insert 100 of figure 2, and comprises a threaded bore 302 defining thread locking deformations 304, 306 at a first axial position and thread locking deformations 308, 310 at a second axial position. Deformations 304, 308 correspond to their opposing deformations 306, 310 and may be formed by crimping.

The deformations 304, 308 are similar but opposite to the deformations 306, 310 and as such only the deformations 304, 308 will be described in detail.

The deformation 304 has a tapered run-in region 312 and a tapered run-out region 314. The deformation 308 has a tapered run-in region 316 and a tapered run-out region 318. These run-in and run-out regions occur as the deformations 304, 308 are formed, and their size can be influenced by the thickness, stiffness and strength of the insert material as well as the size and speed of the deformation tool. For example, the run-in and run-out regions of the insert 300 are significantly longer (axially) than those of the insert 100 and as such the insert 300 may have been made with softer material, thinner sidewalls or a deeper deformation process.

It can be seen that as the run-out region 314 ends, the run-in region 316 begins. The thread locking effect begins as soon as the run-in region starts, and as such a continuous thread locking effect is seen by placing the run-out region 314 and run-in region 316 close to each other.

In addition, known screws often have a natural end taper (the "as-rolled" end). This is shown in figure 5b in which a screw 30 is shown engaging the insert 300. The screw 30 has a tapered "as-rolled" end 32.

It will be appreciated that the tapered end 32 of the screw 30 engages with the female taper of the run-in region 316 to provide and additional thread locking effect. This further enhances the aforementioned benefit.

Turning to figures 6a and 6b a part of an insert 400 is shown comprising a bore 402 open to receive a screw 50.

The bore 402 defines an internal thread 404. The thread comprises a tapered region 406. As shown, the tapered region 406 is at an angle A to an axis X of the insert 400.

The screw 50 defines an external thread 52 which also comprises a tapered region 54 formed "as-rolled". The tapered region 54 is at an angle B to the main axis of the screw (not shown, but assumed to be coincident with X).

As the screw 50 is turned and advances into the bore 402, the tapered region 54 eventually engages with the tapered region 406. As this occurs, the tapered region 54 urges and elastically deforms the tapered region 406 radically with respect to the axis X. As a result, the tapered region 406 attempts to resile to its undeformed state and thereby clamps the screw 50 providing a thread locking feature.

Variations of the above embodiment fall within the scope of the present invention.

The crimping operations performed in figures 4b and 4c may be performed simultaneously by a single tool.

The thread locking may be formed by any known local deformation technique- for example to provide only a single circumferentially deformed region which would provide the advantage. Crimping would of course normally provide two oppositely located deformed regions.

Additionally, further crimps or deformations around the circumference of the insert may be added.

Further thread locking features along the axial length of the insert may be provided.

The thread locking features described herein may be used in conjunction with other thread locking technologies. For example, the male threaded member may comprise a

plastics coating. The invention would enhance the performance of the plastics coating as it would be less likely to be eroded or rubbed off if it only had to engage a thread locking feature proximate the second end of the insert.

The external features (i.e. the cylindrical portions and the grooves) are optional and can be replaced by any number of portions with any desired mechanical features such as axial grooves or knurls.

The threaded portion 132 does not have to run the full distance of the bore, and can extend through part of it, as long as the thread locking feature is provided proximate the lowermost region in which the male member engages.

The run-out region 314 and the run-in region 316 may overlap.

The bores mentioned in any of the above embodiments may be through or blind.