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EP-4508339-B1 - MARKED THREADED FASTENER MANUFACTURE AND FASTENER

EP4508339B1EP 4508339 B1EP4508339 B1EP 4508339B1EP-4508339-B1

Inventors

  • Spampatti, Matteo
  • Kurz, Tobias
  • Wielgat, Marcin

Dates

Publication Date
20260506
Application Date
20230328

Claims (9)

  1. Method for manufacturing a marked threaded fastener (1) comprising, - a providing step (11), in which a threaded fastener (1) having at least one marking surface (2) is provided, - following the providing step (11), a roughening step (12), in which the marking surface (2) is roughened, and - following the roughening step (12), a marking step (14), in which a marking (4) is applied to the at least one marking surface (2), wherein the roughening step (12) is a sandblasting step, in which the marking surface (2) is roughened by sandblasting.
  2. Method according to claim 1, characterized in that the marking surface (2) is a spanner flat.
  3. Method according to any of the preceding claims, characterized in that the threaded fastener (1) is a nut having a threaded bore therein.
  4. Method according to any of the preceding claims, characterized in that the threaded fastener (1) is a stainless-steel fastener.
  5. Method according to any of the preceding claims, characterized in that in the roughening step (12), the marking surface (2) is roughened to have a gloss ranging from 5 gloss units to 50 gloss units, inclusive.
  6. Method according to any of the preceding claims, characterized in that the method further comprises, following the roughening step (12), a coating step (13), in which the roughened marking surface (2) is coated with at least one coating layer (3) or at least one overcoat layer (8), wherein the marking step (14) follows the coating step (13).
  7. Method according to any of the preceding claims, characterized in that the marking step (14) is a printing step, in which the marking (4) is printed on the at least one marking surface (2).
  8. Method according to any of the preceding claims, characterized in that the marking (4) is a barcode.
  9. Threaded fastener (1), manufactured by a method according to any of the preceding claims, having a marking surface (2), on top of which at least one coating layer (3) or overcoat layer (8) is provided, on top of which at least one marking (4) is provided, wherein the marking surface (2) has gloss ranging from 5 gloss units to 50 gloss units, inclusive.

Description

The invention relates to a method for manufacturing a marked threaded fastener and to a threaded fastener. EP1171716 B1 describes threaded nuts having 2D barcodes located thereon. DE 102021106817 A1 discloses providing optoelectronically readable code on a nut, wherein a distance of the code from edges of wrench surfaces of the nut is proposed. Applying barcodes to threaded fasteners, such as nuts, can pose technical challenges, in particular when the fasteners are steel fasteners, such as carbon steel fasteners or stainless-steel fasteners, provided with a hydrophobic functional coating, such as a friction-modifying coating and/or a corrosion protective coating. Laser-marking might damage surfaces, thereby promoting corrosion.Throughput of laser-marking might be limited, which might be disadvantageous in view of mass production.Ink printing might imply adhesion issues when printing on functional top coatings, resulting in the code marking being not environmentally robust enough for certain applications, in particular outdoor applicationsMarkings on bright surfaces might be difficult to read out. It is an object to provide a method for manufacturing a fastener attending these and/or other technical challenges, and/or to provide a durable and machine scannable marking solution, in particular for carbon steel or stainless fasteners, in particular suitable for mass production. The object is solved by a method according to claim 1 and by a fastener according to claim 9. Dependent claims describe preferred embodiments of the method. The invention proposes a method for manufacturing a marked threaded fastener comprising, a providing step, in which a threaded fastener having at least one marking surface is provided,following the providing step, a roughening step, in which the marking surface is roughened, in particular mechanically roughened, andfollowing the roughening step, a marking step, in which a marking is applied to the at least one marking surface, in particular over the at least one coating layer, wherein the roughening step is a sandblasting step, in which the marking surface is roughened by sandblasting. The invention moreover proposes a threaded fastener, manufactured by the method described here, having a marking surface, on top of which at least one coating layer or overcoat layer is provided, on top of which at least one marking is provided, wherein the marking surface has gloss ranging from 5 gloss units (GU) to 50 gloss units (GU), inclusive. Accordingly, the gloss is >= 5 GU and <=50 GU. Accordingly, the threaded fastener is explicitly roughened before the code is applied by printing. Increased surface roughness resulting from the roughening step might increasing adhesion of the subsequently applied marking. Additionally or alternatively, said increased surface roughness might entail increased dullness, which in term might improve readability of the marking. The roughening step can include roughening the entire surface of the threaded fastener or just parts of said surface. The marking typically extends only over a part of the at least one marking surface, but it might also extend over the entirety of the at least one marking surface. The marking is typically limited to the at least one marking surface, but in other embodiments, the marking might also extend beyond the at least one marking surface, into other surface areas of the threaded fastener. The marking surface is the surface on which the marking is intended to be placed. Preferably, the marking surface is a spanner flat, that is a usually generally flat surface intended to be engaged by a spanner or a wrench for imparting torque onto the threaded fastener. Preferably, the threaded fastener has six spanner flats so as to form a hex drive. The threaded fastener could for example be a screw. Preferentially, the threaded fastener is a nut having a threaded bore therein. The nut can be placed on the shaft of an expansion anchor. The roughening step is a sandblasting step, in which the marking surface is roughened by sandblasting. Sandblasting includes propelling a stream of abrasive material against the marking surface. This may provide for particularly efficient roughening. The method might be particularly suitable for steel fasteners, more preferably stainless-steel fasteners. It is advantageous that in the roughening step, the marking surface is roughened to have a gloss ranging from 5 gloss units to 50 gloss units, inclusive (i.e. the gloss is >= 5 GU and <=50 GU). This can provide particularly good readability and/or adhesion of overlayers. Preferably, the method further comprises, following the roughening step, a coating step, in which the roughened marking surface is coated with at least one coating layer or with at least one overcoat layer, wherein the marking step follows the coating step. This can further improve performance and/or durability. The coating step can include coating the entire surface of the threaded fastener or just p