GB1587082A - Fixing devices made of stainless steel - Google Patents

Description

(54) IMPROVED FIXING DEVICES MADE OF STAINLESS STEEL (71) We, UGINE ACIERS, a body corporate organised under the Laws of France of 10, rue du General Foy 75361 Paris Cedex08, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to improved fixing devices made of stainless steel.

The devices which form the subject of the invention are designed to be sunk or screwed into soft materials so as to act as a support, or to ensure that there is a link between different components or parts. More specifically, these devices comprise nails, spikes, hooks, claws, clasps, as well as wood screws and so on, composed of stainless steel which are designed to be sunk or screwed, without first providing a screw-threaded hole, at least partially into relatively soft materials such as wood, plaster, cardboard and certain plastics, and to be kept ir situ by means of the frictional forces which are exerted between the surfaces which are thus placed in contact.

It is well known that the excellent resistance to corrosion of stainless steels justifies their use for numerous fixing devices and in particular for those which are exposed to moist or corrosive atmospheres. Unforunately, experience has shown that in many cases these devices which are sunk at least partially into soft materials offer insufficient resistance to wrenching. This defect is caused by the fact that the extremely smooth undeteriorating surface of the various grades of stainless steels does not adhere sufficiently to the majority of materials which it may touch.

For these reasons, the use of stainless steel nails of all types, such as, for example, the dog nails used for joining the covering elements of a roof to the timber framework has not developed as anticipated.

Various solutions have been suggested for avoiding this poor retaining power of stainless steel nails. It has been suggested in particular that they be replaced by screws, but this solution is frequently neither practical nor economically feasible.

The same applies to the solution which consists in altering the surface of the stainless steel nails so as to create roughnesses which would increase their adherence. The latter solution has the particular disadvantage of making it more difficult to insert these nails, and this is not the effect desired.

Quite surprisingly, we have found a means for producing. a fixing device composed of stainless steel which provides at least one drive-in union or link between parts to be joined and which, while still remaining just as easy to drive in, offers a resistance to wrenching superior to that of similar devices composed of ordinary steel.

The invention provides a fixing device comprising at least one stainless steel part which is unthreaded or provided with a threading or with external reliefs, which is adapted to be introduced forcefully into one or more softer materials which do not have a preliminary hole or which are pierced with a preliminary unthreaded hole having an average cross-section smaller than the crosssection of the part of the device which is to be accommodated inside, and in which at least the part or parts of the device which are intended to be driven in are coated with a thin adherent layer of copper or copperbased alloy.

The invention also provides a method of making a joint, which comprises introducing a fixing device as defined above forcefully into a softer material which does not have a preliminary hole or which has been pierced with a preliminary unthreaded hole having an average cross-section smaller than the cross-section of the part of the device which is to be accommodated inside.

The core of these devices may be composed of any type of stainless steel such as austenitic, austenoferritic, semi-ferritic, ferritic or martensitic steels. The external dimensions of the devices according to the invention such as diameter, length, diameter of the head, shape of the part designed to be sunk or screwed, and so on, may be whatever desired and they generally reproduce the normally used ranges of dimensions.

The coating of copper or of copper-based alloy on the stainless steel may be applied by any suitable method such as chemical displacement, electrolytic deposition, immersion in a copper-based or copper alloy-based bath metallisation by spraying or again sheathing by various methods followed by codeformation. The novel products obtained in this way have the external appearance of copper or copper-based alloys, such as brasses or bronzes, but they maintain the essential mechanical properties of resistance to deformation and to breakage which characterise the grade of stainless steel of which they are formed.

For certain applications, the copper plating is voluntarily limited to the part which is designed to be sunk into the soft material or materials such as wood or plaster. For other - applications, it is preferable completely to cover the fixing device with eopper. This is the case, for example, with roofing hooks, intended for fixing slates to the timber framework; the overall copper plating allows the resistance to wrenching of the spike which penetrates the timber to be combined with excellent resistance to atmospheric corrosion.

Furthermore, the hooks have an identical appearance to that of hooks made of copper or of bronze and they acquire an almost identical patina with time.

Moreover, it is not necessary for the copper coating or copper-based alloy coating to be perfectly continuous, even in the area of penetration into the soft material. There may be deficiencies or cracks. In - each case, the steel which is thus exposed to the effect of the atmosphere or the humidity will exhibit the normal behaviour of the stainless steel of which it is composed. It has also been unexpectedly observed that the risk of the stainless steel corroding through the formation of a cell with the copper is practically nonexistent. As mentioned above, the invention applies to any fixing device made of stainless steel comprising at least one part securing a union or link as a result of sinking or screwing into a softer material.In the case where a joint by sinking is very desirable, in particular owing to vibrations, the adherence may be further increased by enlarging the contacting surface, for example by producing threads or various rough parts. In each case, the presence of the copper layer will increase significantly the effectiveness of the threaded surfaces or of these rough parts.

Composite fixing devices may also be produced in which only part is made of stainless steel, this part comprising the area for penetration into the soft material and this area at least being covered with copper. The fixing devices may be locked by penetration not only into relatively soft materials such as wood or plaster but also into harder materials such as concretes or certain types of rock. In certain cases, preliminary holes may be pierced into materials of this type in order to make it easier for the copper-plated stainless steel part which has to produce the union or link to penetrate.

The layer of copper or copper-based alloy preferably has a thickness of from 5 to 50 micrometres.

WHAT WE CLAIM IS:- 1. A fixing device comprising at least one stainless steel part which is unthreaded or provided with a threading or with external reliefs, which is adapted to be introduced forcefully into one or more softer materials which do not have a preliminary hole or which are pierced with a preliminary unthreaded hole having an average cross-section smaller than the cross-section of the part of the device which is to be accommodated inside, and in which at least the part or parts of the device which are intended to be driven in are coated with a thin adherent layer of copper or copper-based alloy.

2. A device according to claim 1, in which the layer of copper or of copper-based alloy has a thickness of from 5 to 50 micrometres.

3. A device according to claim 1 or 2, in which the layer of copper or copper-based alloy has been deposited by chemical displacement, electrolysis, metallisation by spraying, immersion in a copper-based or copper-alloy-based bath, or sheathing followed by codeformation.

4. A fixing device according to claim 1, substantially as hereinbefore described.

5. A method of making a joint, which comprises introducing a fixing device as claimed in any one of claims 1 to 4 forcefully into a softer material which does not have a preliminary hole or which has been pierced with ta preliminary unthreaded hole having an average cross-section smaller than the crosssection of the part of the device which is to be accommodated inside.

6: A method according to claim 5, in which the layer of copper or copper-based alloy has a thickness of from 5 to 50 micrometres.

7. A method according to claim 5 or 6, in which the softer material is wood, plaster, concrete or rock.

8. A method according to claim 5, substantially as hereinbefore described.

9. A joint when made by a method according to any one of claims 5 to 8.

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

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. desired and they generally reproduce the normally used ranges of dimensions. The coating of copper or of copper-based alloy on the stainless steel may be applied by any suitable method such as chemical displacement, electrolytic deposition, immersion in a copper-based or copper alloy-based bath metallisation by spraying or again sheathing by various methods followed by codeformation. The novel products obtained in this way have the external appearance of copper or copper-based alloys, such as brasses or bronzes, but they maintain the essential mechanical properties of resistance to deformation and to breakage which characterise the grade of stainless steel of which they are formed. For certain applications, the copper plating is voluntarily limited to the part which is designed to be sunk into the soft material or materials such as wood or plaster. For other - applications, it is preferable completely to cover the fixing device with eopper. This is the case, for example, with roofing hooks, intended for fixing slates to the timber framework; the overall copper plating allows the resistance to wrenching of the spike which penetrates the timber to be combined with excellent resistance to atmospheric corrosion. Furthermore, the hooks have an identical appearance to that of hooks made of copper or of bronze and they acquire an almost identical patina with time. Moreover, it is not necessary for the copper coating or copper-based alloy coating to be perfectly continuous, even in the area of penetration into the soft material. There may be deficiencies or cracks. In - each case, the steel which is thus exposed to the effect of the atmosphere or the humidity will exhibit the normal behaviour of the stainless steel of which it is composed. It has also been unexpectedly observed that the risk of the stainless steel corroding through the formation of a cell with the copper is practically nonexistent. As mentioned above, the invention applies to any fixing device made of stainless steel comprising at least one part securing a union or link as a result of sinking or screwing into a softer material.In the case where a joint by sinking is very desirable, in particular owing to vibrations, the adherence may be further increased by enlarging the contacting surface, for example by producing threads or various rough parts. In each case, the presence of the copper layer will increase significantly the effectiveness of the threaded surfaces or of these rough parts. Composite fixing devices may also be produced in which only part is made of stainless steel, this part comprising the area for penetration into the soft material and this area at least being covered with copper. The fixing devices may be locked by penetration not only into relatively soft materials such as wood or plaster but also into harder materials such as concretes or certain types of rock. In certain cases, preliminary holes may be pierced into materials of this type in order to make it easier for the copper-plated stainless steel part which has to produce the union or link to penetrate. The layer of copper or copper-based alloy preferably has a thickness of from 5 to 50 micrometres. WHAT WE CLAIM IS:-

1. A fixing device comprising at least one stainless steel part which is unthreaded or provided with a threading or with external reliefs, which is adapted to be introduced forcefully into one or more softer materials which do not have a preliminary hole or which are pierced with a preliminary unthreaded hole having an average cross-section smaller than the cross-section of the part of the device which is to be accommodated inside, and in which at least the part or parts of the device which are intended to be driven in are coated with a thin adherent layer of copper or copper-based alloy.

2. A device according to claim 1, in which the layer of copper or of copper-based alloy has a thickness of from 5 to 50 micrometres.

3. A device according to claim 1 or 2, in which the layer of copper or copper-based alloy has been deposited by chemical displacement, electrolysis, metallisation by spraying, immersion in a copper-based or copper-alloy-based bath, or sheathing followed by codeformation.

4. A fixing device according to claim 1, substantially as hereinbefore described.

5. A method of making a joint, which comprises introducing a fixing device as claimed in any one of claims 1 to 4 forcefully into a softer material which does not have a preliminary hole or which has been pierced with ta preliminary unthreaded hole having an average cross-section smaller than the crosssection of the part of the device which is to be accommodated inside.

6: A method according to claim 5, in which the layer of copper or copper-based alloy has a thickness of from 5 to 50 micrometres.

7. A method according to claim 5 or 6, in which the softer material is wood, plaster, concrete or rock.

8. A method according to claim 5, substantially as hereinbefore described.

9. A joint when made by a method according to any one of claims 5 to 8.