Surface coating device of core body

#This invention relates to a surface coating device wherein the surface of a body is coated with plastic synthetic resin, e.g. polyvinyl chloride to a given thickness and, in addition, a plurality of discontinuous projections of the coating resin are formed all over the surface.

#Of the stays or posts that are used for agricultural or marine purposes, those made of a metallic tube with its surface being coated by synthetic resin for the purpose of rust prevention have become extensively used nowadays in lieu of those made of natural tree branches or bamboo which are apt to get rotten fast. However, the surface of a post coated with synthetic resin by an ordinary extruding machine is slippery. When a rope or the like is tied to the post, it easily moves out of position. In order to solve this problem, the surface, after being coated with said synthetic resin, must further be made uneven. To do this, a method as described next has conventionally been pursed. The conventional way has been that by the use of an adequate extruding machine, the surface of the body is coated with plastic synthetic resin and, at the same time, several continuous projection lines are formed all over the surface in the axial direction of the elongate body. Then, before the coated synthetic resin is hardened, the projection lines are pressed or cut off at a given distance by proper means to form secondary discontinuous projection portions. The aforesaid method, however, has been proved defective as it invites a high production cost resulting from a complicated manufacturing process, extra labor and excessive waste of synthetic resin.

#One of the prime objects of the present invention is to provide a surface coating device enabling the coating of the surface of a body with synthetic resin and, at the same time, by repeating the operation of supply and nonsupply of said synthetic resin to the grooved portion of dies affixed on the tip of the coating device main body, to form a plurality of discontinuous projections simultaneously with said coating resin.

#FIG. 1 is a vertical section of the central part of a coating device in accordance with the present invention.

#FIG. 2 is a perspective, particaly sectional, view of the device of FIG. 1 showing grooves of the fixed die out of alignment with grooves of the moveable die.

#FIGS. 1(a) to 3(d) are perspective views of pipes coated with synthetic resin and provided with projections, in various patterns, in accordance with the invention.

#The embodiments of the present invention will be explained with reference to accompanying drawings.

#As shown in FIG. 1, the main body (1) of the device has a screw (1a) inside a cylinder (1b) to force resin into resin chamber (3) having a nozzle (2) therein. On the outer side of an opening (3a) of said chamber (3) a fixed die (4) is affixed. Between said chamber (3) and fixed die (4) a moveable die (5) is provided, rotatable freely on bearings (5a) (5b). The dies (4) (5) are provided with resin passages (4') and (5') respectively having diameters corresponding to the thickness of the coating resin and the diameter of these passages is designed to be the same as or a bit less then the diameter of the opening (3a) of the resin chamber (3).

#On the inner surface of the respective resin passages (4') (5') of the two dies (4) (5) are formed, passing through to the direction of thickness, a plurality of respective grooves (6) (7) and, by the rotation of said moveable die (5), the respective grooves (6) of the fixed die (4) can be moved into alignment jointly or individually with the grooves (7) of the moveable die (5).