| 摘要 |
The disclosed invention is a method and an apparatus for wiping excess metallic coatings from meshes in the contemporary continuous hot dip coating process through electromagnetic induction. For the necessary electromagnetic induction, the coated mesh emerging out of a hot dip bath is further passed, without any physical or electrical contact, through a loop of electrical conductors carrying an alternating electric current of suitable frequency, waveform shape and magnitude. The conductors constituting the said loop are located completely outside the hot dip bath, and are shaped and oriented in order not to be parallel to any links of the coated mesh running through. The running mesh and the liquid metallic coating layers thereon are thus subjected to the action of an effectively localized, externally applied alternating magnetic field, which has components substantially parallel to all the links of the mesh. Consequently, alternating currents are induced in the coating layers in the vicinity of the conductor loop, and interactions between the existent magnetic flux and induced currents within the coating layers bring about effective squeezing and wiping of the excessive liquid coating carried on the running mesh. The squeezed out and wiped away liquid coating mass flows back to the bath under gravity and is recovered. The extent of squeezing and wiping is controlled through a variation of the magnitude of the loop current on-line. In preferred embodiments, the conductors of the loop are substantially covered on all sides except those directly facing the running mesh with soft, Horseshoe or C shaped ferromagnetic cores. The conductors are tubular through which some coolant is circulated. Also, wiping is carried out under inert gaseous atmosphere covering the coating layers on the running mesh. Furthermore, the invention also covers some preferred modified embodiments to suit various types of commonly manufactured meshes, such as, hexagonal mesh, chain link mesh, square or rectangular mesh and expanded wire or sheet mesh in the conventional hot dip metal coating practice. 10-> - - 4 x __1 ___ ___ __ _ I Ln 1 I F 5 If - -i x S C SE 5Pc KP CASE-4 XY I |
