Surface coating device of bamboos

This invention relates to a surface coating device of bamboos including the stays having anti-corrosion, insect-prevention property and produced by said device characterizing that a nozzle having an opening permitting to freely pass natural materials such as bamboos or tree branches whose outside diameter is irregular is inserted in the resin chamber set up adjacent to the cylinder pushing out melted synthetic resin such as vinyl chloride and by passing said natural materials or the materials whose surface has been evenly coated beforehand by chemicals having adhesiveness like tar as well as anti-corrosion, insect-prevention property at a constant speed slowly rotating from backward of said nozzle, said melted resin successively fed in to said chamber adhesively coats the surface of said materials in a state of film.

This invention relates to a surface coating device of bamboos or tree 
branches with their surface having knots or shaping uneven wherein the 
surface of these materials whose outside diameter is irregular is coated 
by a thin synthetic resin film. 
Hitherto when such natural materials as bamboos or tree branches are used 
for clothes poles in an ordinary household or for agricultural or fishing 
stays these materials had to be guarded against causing to decay or 
worning-out originating in worm-eating. As a counter measure a method 
coating the surface of these bamboos by an adequate synthetic resin is 
conventionally known widely. Speaking in a concrete way an example is 
cited in that a vinyl tube formed cylindrical beforehand is put on a 
bamboo and by the use of heat-absorbing contractility of said tube 
resulting from the heating of the cylindrical surface by hot water or 
other pertinent ways said tube can be tightly stuck to the bamboo surface. 
In another example a bamboo is put in to a melted resin supplied 
successively through a pushing mechanism to be coated by the film of said 
melted resin while being thinned all around its surface. 
The former example, however, as has been explained above, needs a good 
number of work processes so that it has a defect of remarkably lowering 
down the production efficiency. As to the latter example, a bamboo merely 
passes through the melted resin solution depending entirely upon the 
adhesiveness of resin so that to obtain a uniform coating of resin film is 
extremely difficult. Even if the coating in the aforesaid two examples has 
been done perfectly, due to the fact that a cooled and then solidified 
resin film still potentially retains contractility within, when the 
bamboos are cut to uniform their length after the coating process, the 
resin film shrinks on account of said contractility and the end portion of 
finished product is inevitably exposed. Furthermore, as a perfect contact 
between the bamboo and the resin film can not be achieved on account of 
the presence of latent contractility as aforesaid, coming-off of the resin 
film from the finished product is apt to occur thus the coating effect 
which is the primary object is lessened. 
The present invention is designed to solve all the aforesaid defects at a 
stroke and one of its chief objects is to offer a novel device wherein the 
surface of bamboo is made possible to be coated uniformly by the resin 
film through passing the bamboo rotating slowly at a constant speed in the 
melted resin that is successively fed by a pushing mechanism. 
Another object is to offer a device wherein the end portion of bamboo 
doesn't expose to air nor the resin film comes off from inside even if 
said film gets cooled and then shrinks by closely contacting it directly 
or through applying a sticky tarry substance in-between on the surface of 
bamboo. 
Still another object is to offer a device wherein the forming of coating 
film having a different surface structure is made possible through 
properly varying the quality, color & etc. of the feeding resin by 
providing a plural number of pushing mechanism of melted resin on the body 
of coating device. 
A further object is to offer a device wherein the operational efficiency 
can be greatly elevated by automatically conducting the coating of bamboo 
successively. 
A still further object is to offer, if so found necessary, a bamboo to be 
coated to enable it from getting decay or worm-eaten through applying a 
tarry substance having antisepsis and adhesiveness between the bamboo and 
the resin film. 
The primary and other pertinent objects and the characteristics of this 
invention enumerated above in a concrete way are undoubtedly clear by the 
explanation described hereunder relating to this invention.

Description is made hereunder on the embodiments of this invention with 
reference to the accompanying drawings. 
As shown in FIG. 1, the device (1) consists of a push cylinder (1'), a 
melted resin chamber (2) communicating a die (3) with one side, a nozzle 
(4) inserted and affixed on the inside of said chamber (2) coaxially and 
rotating members consisting of belts (5) or rollers (5') that move forward 
a bamboo (a) at a fixed speed while giving a constant rotation at front 
and back of the body of the device (1). 
The opening (4') at the end of the nozzle (4) has a bore freely permitting 
the bamboo (a) having an irregular outside diameter to pass through. 
A bamboo or a tree branch is inserted in to the chamber (2) at a given 
speed slowly rotating by means of rotating members (5) (5') through the 
nozzle (4) of the coating device body (1) made up as aforementioned hence 
the melted resin successively fed to the chamber (2) through said push 
cylinder (1') is made to coat the surface of bamboo (a). 
Namely, the bamboo (a) inserted in to the chamber (2) moves to the rotating 
members (5) (5') lying ahead from the die (3) in a state of its end tip 
being coated by resin and under this state the bamboo (a) moves forward in 
which the amount of melted resin that is fed to the chamber (2) from the 
push cylinder (1') varies according to the diameter of the bamboo (a) and 
its forwarding speed but represents an amount sufficient enough to keep 
the resin film (b) that has been spread as thin as possible unbreakable 
thus the resin constantly extends forward to enable forming a resin film 
(b) having a standard thickness. 
At the same time said bamboo (a) is given a slight rotation then said resin 
film is pulled at a fixed angle against the direction of axis of bamboo 
(a) and is coated on the surface of said bamboo (a) likely in a state of 
being wound up. Accordingly said resin film is assuredly stuck to the 
surface of said bamboo (a) in a uniform thickness exactly according to the 
unevenness of the bamboo surface without allowing the presence of air 
between the bamboo surface and the resin film. 
In addition in order to further enhance the effects against corrosion and 
damage by worms as shown in FIG. 2, the surface of bamboo (a) is applied 
with a tarry substance (c) at first then coated by the resin film after 
inserting it into the chamber (2) having said structure thus helped by all 
the characteristics of anti-corrosion, insect-prevention and adhesiveness 
which the tarry substance (c) natively owns, presence of air between the 
bamboo (a) and the resin film can perfectly be evaded even if a rotation 
is not specifically given. Accordingly the corrosion of bamboo and the 
peeling-off of resin film resulting from the presence of air which have 
hitherto been experienced never occur thus the durability is remarkably 
improved. 
FIG. 5 represents another embodiment wherein further one more cylinder (6) 
is provided between the push cylinder (1') of the device of the present 
invention and the die (3). In this case the lower end of the push cylinder 
(6) is open to the resin chamber (2) for coating purpose so that in 
addition to the operational effect as described above the strengthening of 
resin film is made possible through properly varying the quality of resin 
(d) that is fed to the respective cylinders (1') (6) and by changing the 
color of melted resin fed from the cylinder (6), coloring of surface can 
optionally be changed thus it possesses excellent effects. 
All the aforesaid embodiments describe the bamboo (a) pass rotating through 
the chamber (2) respectively but there are instances where a similar 
coating effect can be attained by the spreading nature of the coating 
resin that is put in use. In order to attain an anti-corrosion, 
insect-prevention stay after applying beforehand a tarry substance on the 
surface of bamboo, there is a way of applying same either by a brush or a 
spray gun on the surface of bamboo but it is also possible to discharge a 
tarry substance having a constant viscosity from the end tip of space 
created by the remodeling of the nozzle of push cylinder of said structure 
to a double-tube system. 
Description has been made as to the fitting embodiments of surface coating 
device of bamboos in accordance with the present invention as above but 
any alteration excepting those aforementioned is also possible so long as 
it doesn't cross the scope of the spirit and patent claims to be described 
later on the present invention.