Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Patent
1996-01-03
1997-09-30
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
264296, 264322, 264DIG41, 425392, 425515, 425520, 493255, 493308, B29D 2320, B29C 6500
Patent
active
056723083
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for molding a seal portion of a tubular body of synthetic resin, wherein the seal portion of the tubular body is pressed flat, fused and sealed.
BACKGROUND OF THE INVENTION
According to a prior art, a seal portion of a tubular body of synthetic resin is formed as follows. The end portion of the tubular body is pressed by a pair of opposed clamps until it becomes flat. Then, the end portion projecting from the clamps is heated and fused by a heater. Thereafter, the end portion is pressed from front and back sides and sealed by a sealing mold.
According to the prior art, the seal portion of a synthetic resin made tubular body is formed by being pressed with the sealing mold after being heated and fused. Therefore, side projecting portions 4 are undesirably formed at both sides of the seal portion 5, which is the lowest part of the tubular body I (but shown as the top portion in Figures), as shown in FIG. 15.
According to the prior art, the seal portion is formed as the projecting end portion is pressed by the sealing mold after being fused by the heater. Therefore, some fused synthetic resin at the end portion of the tubular body freely flows and comes out of the mold, forming an irregular thick portion as shown in FIG. 16.
Further, since the projecting side portions are projectedly formed at both sides of the seal portion, fingers may be hurt by them while users are using the tube.
Further, the seal portion is formed by the sealing mold as described above, so that it is shaped such as shown in FIG. 15. It is impossible to form the seal portion an any desired shape such as one, for example, comprising a hanger portion for being hung on a bar.
According to the prior art, the seal portion is formed simply by being pressed by the sealing mold after being fused, so that the adhesive strength of the seal portion is not firm enough. Therefore, in a case in which a substance with higher viscosity is filled in the tube, the seal portion would easily be torn when an user squeezes the substance out of the tube. Then, the substance may be squeezed from the torn seal portion.
Further, when the tubular body is composed of plural layers of high gas-barrier quality synthetic resin, the synthetic resin decomposes and foams by an effect of heat while sealing the seal portion. This would cause a leak of a substance out of the tube.
The invention resolves these problems. Therefore, an object of the invention is to increase density of the seal portion and to form the seal portion in a desired shape.
SUMMARY OF THE INVENTION
A method for forming a seal portion of a tubular body of synthetic resin according to the invention will now be explained. First, clamp an end portion of a tubular body of synthetic resin flat by a pair of clamps. Then, heat and fuse a projecting end portion projecting out of the clamps. Finally, press the projecting end portion to form a desired seal portion shape, while reducing a cubic volume of the projecting end portion to 0.65-0.80 times the original volume.
Another method for forming a seal portion of a tubular body of synthetic resin according to the invention comprises the following process. First, clamp an end portion of a tubular body of synthetic resin flat by a pair of clamps. Second, heat and fuse a projecting end portion projecting out of the clamps. Finally, press the projecting end portion to form a desired seal portion shape, while reducing and restricting decomposition and foam of the synthetic resin.
Prior to pressing the projecting end portion into the seal portion, it is desirable that side projecting portions are bent inside. The side projecting portions are formed protrudely from both sides of the projecting end portion while the projecting end portion is heated and fused.
It is also desirable that each of the side projecting portions is bent toward each other along a line about 0-0.5 mm inside from the edge of the flattened end portion.
Apparatus for forming a seal portion of a tubular
REFERENCES:
patent: 2028112 (1936-09-01), Westin
patent: 2413323 (1946-12-01), Hills
patent: 2488212 (1949-11-01), Lloyd, Jr.
patent: 2562523 (1951-07-01), Brunet
patent: 3032454 (1962-05-01), Rohdin
patent: 3063890 (1962-11-01), Saumsiegle
patent: 4196825 (1980-04-01), Kincaid
patent: 5373965 (1994-12-01), Halm et al.
Eashoo Mark
Silbaugh Jan H.
Yoshino Kogyosho Co. Ltd.
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