JPS5931451B2 - Method for manufacturing tube containers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tube-shaped container for storing a fluid such as toothpaste.As a conventional method for manufacturing tubes, the tube body is made in advance by profile extrusion molding. The overwhelming majority of methods involve inserting it into a tube mold and using the injection method to melt the joints of the main body using the heat of the resin in the neck.

Alternatively, a method has been used in which the neck part is manufactured separately from the main body in advance, and then the neck part is fused to the main body and compressed by heating. In these methods, the neck part can be joined to the neck part, making it possible to create a laminated pipe or When a laminated sheet is used, the laminations are not exactly continuous at the seams, resulting in the result shown in the schematic cross-sectional view of FIG. 1 is the outer layer, 2 is the middle layer, and 3 is the innermost layer.

In addition, in this manufacturing method, the adhesion of the joints is weak, and the contents may leak out due to breakage, making it impossible to produce a finished product.Furthermore, it is difficult to match the colors of the body and neck, resulting in poor appearance. There are also drawbacks. There is also a method of integrally molding the main body and neck part from a single piece of Parylin using professional molding. in this case,
There will be no seams, and if you use laminated Parylin, you can create a completely laminated tube, but the mold must be split into a split type, which creates parting lines on the tube body, and may cause characters to be missing during secondary processing such as printing. This becomes a defect in appearance. Furthermore, there are drawbacks such as difficulty in uniformly rolling the wall thickness and the occurrence of burrs. The present invention has overcome these drawbacks, and its gist is to provide a body having an outer diameter that is approximately the same as the inner diameter of the pipe to be formed, a neck that is thinner than the body, and a shoulder that connects the neck and the body. A mandrel made of a thermoplastic synthetic resin is inserted into a pipe whose length is at least longer than the sum of the heights of the body, shoulders, and neck of the mandrel, and the outer surface of the body of the pipe is cooled by an external cooling tube. While covering the pipe and holding the tip of the part of the pipe that protrudes from the mandrel neck with a chuck, heat the vicinity of the pipe corresponding to the mandrel neck to raise the resin temperature above the melting point. The diameter of the part of the pipe corresponding to the mandrel neck is reduced by pulling it on the mandrel axis on the opposite side of the mandrel, and a press fitting for forming that matches the shape of the neck of the tube container is attached to the reduced diameter part. By pressing the pipe against the neck and shoulders of the mandrel to form it into the desired shape and cooling it, a uniform wall thickness can be achieved, and the body and neck become one piece with no seams. Furthermore, even if laminated pipes are used, a tube container with complete lamination can be obtained.

Thermoplastic synthetic resin tubes have a property of shrinking in diameter due to surface tension when heated, and the present invention takes advantage of this. To explain the present invention in more detail, FIG. 2 is a schematic cross-sectional view showing a good laminated state of thermoplastic synthetic resin pipes used in the present invention. All the drawings shown below are schematic cross-sectional views, and FIG. 3 shows a mandrel A having a neck 5, a shoulder 6, and a body 7 inserted into a pipe 4, and the body being inserted into a cooling cylinder 8 from the outside of the pipe. Cool down. Upper tip of pipe 9
is sandwiched between chucks 10 as shown in Figure 4, and the part of the pipe above the shoulder of the mandrel is heated and lifted to the upper opening to form mold B, which integrates the shoulder and neck of the container as shown in Figure 5. Press from the outside as a split mold to create the state shown in Figure 6,
By cooling the mold B, a tube container with uniform wall thickness, high strength, and a seamless body can be manufactured. Reference numeral 11 denotes a groove for forming a threaded portion of the cap of the tube.

As a method for heating and cooling, known methods such as a method using a conventional heater or a method using hot air can be used. In this case, it is preferable to sand the neck of the mandrel so that air can be removed. In addition, the shoulders and neck are thicker,
To make it hard, a mandrel is filled with thermosetting resin or thermoplastic bending resin in advance, and the tube is made by heating and clamping the mold as shown in FIG. 12 is a pre-loaded resin.

Furthermore, by adjusting the heating temperature, the thickness of the shoulders and neck can be adjusted. Any thermoplastic synthetic resin can be used in the present invention, and polyethylene, polypropylene, etc. are often used, for example.

In addition, various laminated pipes can be used; (1) the inner and outer layers are made of polyethylene, the middle layer is made of polyamide or ethylene-vinyl alcohol copolymer resin, and (support) the outer layer is made of polyamide resin, the inner layer is polyethylene, and (3) the outer layer is made of polyethylene. Ethylene-vinyl alcohol copolymer, inner layer polyethylene, (4
) Pipes with two-layer or multi-layer structures, such as an outer layer made of polyethylene and an inner layer made of polyamide, can be used in various combinations. According to the present invention, the wall thickness of the tube is uniform and there is extremely little loss, extrusion molded pipe can be used, which makes it inexpensive, and there is no seam between the tube body and the neck, making it a beautiful and high-class product, making it suitable for the use of laminated pipes. There are various advantages such as no problems.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a tube showing an example of an inconvenience that often occurs when tube containers are made from synthetic resin laminated pipes using the conventional method, and Figure 2 shows that the method of the present invention always maintains a normal laminated structure. Figure 3 is a cross-sectional view of the tube-shaped container that can be produced, Figure 3 is a cross-sectional view showing a container-shaped mandrel inserted into the pipe according to the method of the present invention, Figure 4 is a cross-sectional view showing the tip of the pipe at the shoulder and neck portion of the container. A cross-sectional explanatory diagram showing a state in which the chuck is used to heat the container. Fig. 5 is a cross-sectional explanatory diagram showing a state in which the shoulder and neck of the container are pressed using an external press mold. Figure 7 is a cross-sectional explanatory diagram showing a state in which a tube container is formed by pressing the tube from the outside with a molding die on the shoulder and cooling it to form a tube container. It is a cross-sectional explanatory view of a tube container. DESCRIPTION OF SYMBOLS 1... Outer layer of laminated vibrator, 2... Middle layer of laminated vibrator, 3... Inner layer of laminated pipe, 4... Thermoplastic resin pipe, 5... Neck of mandrel, 6... Mandrel Shoulder part, 7... Mandrel body, 8... Cooling tube,
9... Upper tip of the pipe, 10... Chuck 11 for biting the pipe, groove section provided in the press mold for forming the threaded part of the neck of the tube container, A... Entire mandrel, B...Press mold for forming shoulders and neck.

Claims (1)

[Claims] 1. At least the body of the mandrel is molded from thermoplastic synthetic resin, and includes a body having an outer diameter that is approximately the same as the inner diameter of the pipe to be molded, a neck that is thinner than the body, and a shoulder that connects the neck and the body. The mandrel was inserted into a pipe whose length was longer than the height of the mandrel, shoulder, and neck, the outer surface of the pipe's body was covered with an external cooling cylinder, and the tip of the part of the pipe that protruded from the mandrel neck was gripped with a chuck. In this state, the vicinity of the mandrel neck of the pipe is heated to raise the resin temperature above the melting point, and the chuck is pulled on the mandrel center axis to the opposite side of the mandrel while keeping the pipe body still. The diameter of the part corresponding to the neck of the mandrel is reduced, and a press mold for forming that matches the shape of the neck and shoulders of the tube container is pressed onto the reduced diameter part so as to correspond to the neck and shoulders of the mandrel. A method of manufacturing a tube container by molding a pipe into a desired shape.