FIXING DEVICE

Abstract: The present invention provides a fixing device (1), for anchoring a screw or bolt in a hole in a structure, compris­ ing a flexible sleeve (3) having a nut (5) for receiving the screw or bolt. The nut (5) is fixedly disposed in the sleeve (3) near one end thereof, and the peripheral surface of the nut (5) is enclosed by the sleeve (3). The outer surface of the sleeve (3) is provided with annular ribs (11) for hindering extraction of the radially expanded sleeve (3) from the hole, and at least one axial rib (9) protruding marginally beyond the cylindrical outer surface of the sleeve (3) for hindering rotation of the sleeve (3) during screwing of the screw or bolt into or out of the nut (5).

Description: FIXING DEVICE The present invention relates to a fixing device, comprising a flexible sleeve having at one end a nut for receiving 8 screw or bolt, for anchoring the screw o bolt in a hole i a struc > re. A device of this type which has been known for at least thirty years comprises a rubber flexible sleeve haming a brass or brass-plated hexagonal nut embedded therein at cne of its ends. The sleeve has an integrally moulded annular flange at its other end. The nut is hexagonal in order to anchor it securely in the sleeve. However, the use of a hexagonal nut led to difficulties in the production of the device. A proposal for overcoming these difficulties is described in GB-A-1,392,095. In the device described in this patent specification, the hexagonal nut is replaced by a cylindrical nut which preferably has in its outer surface a circumferential groove for keying the nut into the sleeve. In use of these devices, the sleeve is passed through a hole in, for instance, a sheet metal panel until the flange abuts the panel. A bolt is then passed into the sleeve and is screwed into the nut. As the bolt screws into the nut, the sleeve is compressed axially and is therefore forced to expand radially. The radial expansion of the sleeve produces a protuberance abutting the panel which prevents the device from being withdrawn from the hole. It has recently been proposed to use a fixing device of this type to anchor articles such as "sleeping policemen" or machinery to solid surfaces, such as roads or factory floors. However, it has been found that in cases where considerable force is exerted on the fixing device, for instance by traffic passing at ordinary speeds over a sleeping policeman, it is not possible properly to anchor the device on the surface. Moreover, it has proved difficult fully to insert the bolt in the nut since the whole device tends to rotate during the screwing of the bolt int the nut. It is & ar.. sf the present invention C prW an improved fixing device of the type described abcve. According to the present invention, there is provided 2 fixing device, for anchoring a screw or bolt in a hole in a structure, comprising a flexible sleeve having a nut, for receiving the screw or bolt, fixedly disposed in the sleeve near one end thereof, the peripheral surface of the nut being enclosed by the sleeve, wherein the outer surface of the sleeve is provided with: annular ribs for hindering extraction of the radially expanded sleeve from the hole; and at least one axial rib protruding marginally beyond the cylindrical outer surface of the sleeve for hindering rotation of the sleeve during screwing of the screw or bolt into or out of the nut. Preferably, there are two axial ribs disposed diametrically opposite one another. However, any number of axial ribs can alternatively be used so long as their presence does not interfere with the operation of the annular ribs. The amount the axial rib(s) protrude(s) will depend on the size of the hole into which the sleeve is to be placed. The amount should not be so great as to prevent the annular ribs, once the sleeve has been radially expanded, from contacting firmly the sides of the hole. The amount of protuberance can be readily determined by trial and error experimentation by the skilled person. As a general guide it is preferable that the radius to the outside cf an axial mit should not be more than 110% of the radius of the 5 eve. Preferably, the annular ribs are asymetric about a plane perpendicular to the axis of the sleeve, and mit remote from the nut is parallel to that plane and the other side of each rib is angled inwardly, conveniently at an angle of about 45 ,towards the nut. This facilitates insertion of the sleeve into the hole but makes it much more difficult to extract the radIally expanded sleeve from the hole. The annular and axial ribbing on the sleeve is preferably located in a single central area of the sleeve. Alternatively, the ribbing may extend the whole length of the sleeve or may be formed in a number of separate areas of the sleeve. The ribbing is preferably formed by moulding the sleeve in the appropriate shape. Alternatively the ribs could be cut out of the sleeve or adhered thereto. The sleeve may be made from any flexible material, but is preferably made from an elastomeric material such as natural rubber, synthetic rubber or blends thereof. The elastomeric material may contain pigments, fillers, ant-oxidants, stabilisers or any of the other additives knawn in the art. Particularly suitable elastomeric materials are rubber compositions used to produce vehicle tyres. The nut may be fixed in the sleeve by any of the methods known in the art. For instance the sleeve may be moulded around a nut blank which is subsequently taxed to provide an internal thread. Alternatively, the nut may be adhesively secured or bonded in a recess in a pre-formed sleeve. In a further alternative a corrination of moulding and bonding may be used. The nut may be of any desired shape, but is preferably circular, and may be made from any suitable material such as steel, stainless steel, brass or brassplaned steel. If desired an integral annular flange may be f@rred on the end of the sleeve remote from the nut. This will be necessary if it is intended to insert the sleeve into a holiow space behind a panel. However, it will not be necessary if the hole is formed as a well in a solid structure such as a road or factory floor. It is envisaged that the fixing device of the present invention will be of use in any of the applications for which the prior art fixing devices have been used. However, the fixing device of the present invention will be of particular use in fixing bolts or screws in solid structures such as roads or factory floors. In use in such an application, a hole is formed in the surface and a fixing device according to the invention of appropriate dimensions is placed in the hole. The device will be of such dimensions that the axial ribs engage the wall of the hole. The bolt is then inserted into the sleeve and screwed into the nut. As the bolt is screwed into the nut, any tendency for the sleeve to turn in the hole is removed by the interaction of the axial ribs and the wall of the hole. As the bolt is screwed into the nut, the sleeve is compressed axially and is therefore expanded radially. This brings the annular ribs into tight abutment with the wall of the hole. The annular ribs will be able to physically interlock with rough areas on the wall so that the sleeve is retained in the hole by more than just frIction between the wall and the sleeve. It can thus be seen that the fixing device of the present invention overcomes the disadvantages of knows fixing devices cf the s & e type. One embcdiment of a fixing device acecrà-rig te the invention is described below, by way of example only. wrth reference to the accompanying drawing which is a front view, partly in section, of the fixing device. Referring now to the drawing, the fixing device 1 comprises a cylindrical sleeve 3 made from a high quality rubber, comprising a blend of natural and synthetic rubber together with the appropriate ingredients to give excellent ageing and low set characteristics. Such rubbers andtheirformulation and compounding are well known in the art. The sleeve 3 defines a through bore 4 for receiving therein a bolt (not shown). The device 1 further comprises a circular nut 5 fixed into one end of the sleeve 3. The nut 5 was provided with a pretapped thread and the sleeve was moulded around the blank. The nut 5 was further fixed in the sleeve 3 by application of a bonding agent to the exterior unthreaded area of the nut before the moulding of the sleeve 3. The sleeve 3 has formed on the outside of a central section thereof two diametrically opposed axial ribs 9 and a plurality of annular ribs 11. The axial ribs 9 protrude marginally beyond the outer surface of the sleeve 3, but the edges of the annular ribs 11 are in the same plane as the outer surface of the sleeve 3. The annular ribs 11 each cerise a surface lla remote from the nut 5 which is perpendicular to the axis of the sleeve 3 and a surface : adjacent the nut 5 which is angle inwaroThy tcwarcs ;:- nut 5. In use, the fixing device 1 is placed into, for instance, a blind well in a road surface with its nut 5 adjacent the blind end of the well and its other end adjacent the road surface. The diameter of the well should be the same as or marginally smaller than the diameter of the sleeve including the axial ribs 9. Due te their shape, the annular ribs 11 do not significantly interfere with insertion of the sleeve 3 into the well. A "sleeping policemen" is then fixed to the road surface by passing a bolt through a suitable hole in the sleeping policeman and into the sleeve 3. The bolt is then screwed into the nut 5. Since the axial ribs 9 abt tightly the wall of the well, there is little or no tendency for the sleeve 3 to rotate in the well, thus facilitating screwing up of the bolt. As the bolt is screwed into the nut 5, the sleeve 3 is compressed axially between the nut 5 and the bottom of the sleeping policeman. This causes the sleeve 3 to expand radially, thus bringing the annular ribs 11 into tight abutment with the wall of the well. This of itself will make it difficult to remove the sleeve 3 from the well. However, this effect is enhanced by the shape of the annular ribs 11, the surfaces ila of which will physically interlock with the wall of the well. It has been found that, if a fixing device of the present invention is used, it is extremely difficult for traffic movlng at ordinary, or even excessive, speeds to remove sleeping policemen from a road surface. Using the fixing devices of the prior art, it was possible for traffic to overcome the anchoring effect of the device. Icreover , the * fling device of the present invention has been used to anchor a machine tool to a factory floor. This has proved to be a very effective way of anchoring the machine tool, and there has been no sign of any weakening of the anchorage. It is nonetheless easy to remove the anchored article merely by unscrewing the bolt. This will be facilitated by the presence of the axial ribs 9 which will prevent the sleeve 3 from rotating while the bolt is being unscrewed. It will be appreciated that the fixing device of the present invention has been described above by way of example only and that modifications and variations of detail may be made, as will be apparent to the man skilled in the art, without departing from the spirit and scope of the invention.

Claims: CLAIMS: 1. A fixing device, for anchoring a screw or bolt in a hole in a structure, comprising a flexible sleeve having a nut, for receiving the screw or bolt, fixedly disposed in the sleeve near one end thereof, the peripheral surface of the nut being enclosed by the sleeve, wherein the outer surface of the sleeve is provided with: annular ribs for hindering extraction of the radially expanded sleeve from the hole: and at least one axial rib protruding marginally beyond the cylindrical outer surface of the sleeve for hindering rotation of the sleeve during screwing of the screw or bolt into or out of the nut. 2. The fixing device of claim 1, wherein there are two axial ribs disposed diametrically opposite one another. 3. The fixing device of claim 1 or claim 2, wherein the radius to the outside of an axIal rib is not more than 110% of the radius of the sleeve. 4. The fixing device of any one of claims 1 to 3, wherein the annular ribs are asymmetric about a plane perpendicular to the axis of the sleeve. 5. The fixing device of claim 4, wherein the side of each annular rib remote from the nut is parallel to that plane and the other side of each rib is angled inwardly, towards the nut. 6. The fixing device of claim 5, wherein each rib is angled at 450. 7. The fixing device of any one of claims 1 to 6, which is made from an elastomeric material such as natural rubber, synthetic rubber or blends thereof. 8. The fixing device of any one of claims 1 to 7, wherein the sleeve is moulded around a nut blank which is subsequently tapped to provide an internal thread. 9. The fixing device of any one of claims 1 to 7, wherein the nut is adhesively secured or bonded in a recess in a pre-formed sleeve. 10. The fixing device of any one of claims 1 to 9, and including an integral annular flange formed on the end of the sleeve remote from the nut.

Inventors: WILSON, FRANCIS MICHAEL
Applicants: ROCOL LIMITED
Application year: 1986
Main classification: F16B13
IPC codes: F16B37, F16B13, F16B29