GB1116743A - Metal coated papermaking wire and process and apparatus for making the same - Google Patents

Abstract

In electroplating a paper-making wire the margins of the wire are shielded against deposition of ions of the plating material as the wire is passed through the plating bath. The shielding <PICT:1116743/C6-C7/1> <PICT:1116743/C6-C7/2> may be achieved by pre-coating the margins of the wire with a lacquer or plastic or the margins of the wire may pass between inert shields in the plating bath, the shields preferably being arranged to effect a gradually tapered increase in deposit thickness towards the centre over a limited region adjacent the margins. As shown a paper-making wire 1, as of brass, bronze, phosphor bronze, or stainless steel strands, is fed through a chromic acid bath under a largely immersed inert guide roll 11 and an inert non-immersed roll 12 between lead anodes 14, 15 supported respectively from a ventilating hood 17 and the bottom of a tank 10 of inert plastic-lined steel, cathodic connection to the wire being made via conducting roll 13. The electrolyte is circulated continuously from a large reservoir, being fed in at the bottom of the tank and overflowing into a return trough 16. Resiliently mounted non-conducting edge guides 24 for the wire are supported by arms 28 depending from carriages 29 running on a track 30 on the ventilating hood 17, the limbs 25, 26 of the edge guides masking the margins of the wire completely. To achieve gradual increase in the thickness of the chromium deposit from the margins towards the centre masks 18, 19 are arranged on anodes 14, 15 with V-notches opening out towards the middle of the wire, the masks being slidable on the anodes transversely of the wire to vary the extent of the region in which thickness variation takes place. Preferably the maximum thickness of the chromium coating on the wear side of the wire is 1.4 to 3 times that on the paper-making side of the wire. Typically the strand diameters are from 0.075 to 4 mm, the wear side coating is 0.0025 mm thick and the paper-making side coating is 0.0018 mm thick, and the uncoated margin width is 1.27 to 3.80 cm while the tapered thickness coating width is 3.8 cm. Reference is made in the Specification to paper-making "wires" made of polyamide filaments. Reference has been directed by the Comptroller to Specification 1,024,717.ALSO:A metal papermaking wire, e.g. of brass, bronze, phosphor bronze or stainless steel strands, is electroplated, e.g. with chromium, so that the lateral margins of the wire are shielded against deposition as the wire passes through the plating bath. Preferably shields are arranged to produce a gradually tapered increase in deposit thickness towards the centre over a limited region adjacent the margin, and the maximum thickness of the chromium coating on the wear side is 1.4 to 3 times that on the papermaking side of the wire. Typically the strand diameters are 0.075 to 4 mm., the wear side coating is 0.0025 mm thick and the paper making side coating is 0.0018 mm thick, and the uncoated margin width is 1.27 to 3.80 cm while the tapered thickness coating width is 3.80 cm. Reference is made in the Specification to papermaking wires made of polyamide filaments. Reference has been directed by the Comptroller to Specification 1,024,717