JPS60228134A - Hot gluing method of plastic tape - Google Patents

Abstract

PURPOSE:To facilitate resin seal of an opening edge by using a plastic tape in a following manner, after the plastic tape is partly hot glued to the outside of a metal cylindrical body, the remaining portion of the tape is folded over the edge face and into the inside of the cylindrical body by the use of a special die and a core and by sticking thereto. CONSTITUTION:Pertaining to sealing with plastics of an opening edge portion 10a of a metal cylindrical body 10 from its outside portion 10a3, through the edge face, and then to its inside portion 10a2, firstly, over the whole periphery of the outside portion 10a3 of the opening edge 10a2 a portion of a plastic tape in its width direction is hot glued, and secondly, a die 12 is thrusted to the opening edge 10a of the cylinder 10 to turn the plastic tape 11 inwards and at the same time the foled portion is hot glued to the opening edge face, and without intervals, after insertion of a core 16, into the opening 10a, which has an outside diameter slightly smaller than the inside diameter of the opening, the outside diameter of the core is enlarged by a pressing tool 21 to stick the tape 11 to the inside of the opening edge 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION More specifically, the present invention relates to a method of thermally bonding a Zolastic tag to an open end of a metal cylinder.

(Prior art) Open ends 2a and 3a of a seamless upper can body 2 and a seamless lower can body 3, as shown in FIG. A metal can with a relatively thin body wall and having a bonded circumferential joint 5 is particularly suitable as a pressure-resistant can for storing beer, carbonated drinks, etc. (e.g., internal volume of about 1 to 10 liters). It is proposed as. In this case, the upper can body 2 and the lower can body 3 are usually made from blanks on which a corrosion-resistant coating (for example, a phenol-epoxy coating, or an organosol, etc.) is formed on the inner surface of the can to prevent corrosion of the contents. Since it is formed by a patterning process or the like, the inner surface is protected by a coating film, but the metal is exposed at the end surface 3al (formed by cutting) of the inner open end 3a. Therefore, in order to ensure corrosion resistance against the contents, it is necessary to
It is desirable that the inner circumferential surface 3a2e near the end surface 3al and the inner circumferential surface 3a2e be also covered with the adhesive layer 4.

As a preferable method of coating the end surface 3al and the inner circumferential surface 3a2 with the adhesive 4, the present inventors previously disclosed in Japanese Unexamined Patent Publication No. 58-160114 that the outer circumferential surface of the open end is coated with an adhesive. Bend the protruding part of the thermally bonded glass tape inward in the radial direction so that the base of the protruding part is in contact with the entire surface of the end surface 3aI, and then insert the core into the open end to remove the protruding part. We proposed a method in which the protruding portion is folded back and pressed against the folded protruding Wbk inner circumferential surface 3a2 with a core, the opening end is heated in this suppressed state, and the protruding portion is thermally bonded to the end surface and the inner circumferential surface. As a specific embodiment of the above-mentioned suppression, the core has an elastic sleeve whose outer diameter is equal to or greater than the value obtained by subtracting twice the inner diameter of the opening end Q It has been disclosed that when the core is pushed into the open end using an elastic sleeve, the elastic sleeve is compressed in the radial direction and the elastic force is used to perform the above-mentioned suppression.

(Problem to be solved by the invention) In this case, if the outer diameter of the sleeve is appropriate in relation to its comb hardness,
Thermal bonding is carried out under moderate elastic pressure, without wrinkles or bubbles in the thermally bonded plastic tag.
Further, there is no risk of thinning or cutting at the corner portion of the end face. However, the core gradually wears out during repeated use, the outer diameter of the sleeve decreases, and the pressing force becomes insufficient, making the tape prone to wrinkles and bubbles. The outer diameter of the sleeve also changes due to changes in temperature, and a core that has an appropriate outer diameter in the summer will have its outer diameter reduced due to heat shrinkage in the winter, making it more likely to cause the above-mentioned defects. Conversely, a core with an appropriate outer diameter in the winter increases in outer diameter due to thermal expansion in the summer, and when the core is pushed into the open end, the axial force applied to the protruding part that is folded back increases. It has been found that the tension is too high, which tends to cause problems such as thinning or cutting of the tape at the corners of the end surface during thermal bonding.

(Object of the Invention) The present invention relates to an improvement over the prior art described above, and an object of the present invention is to be able to apply an appropriate pressing force even if the outer diameter of the core sleeve changes to some extent. Another object of the present invention is to provide a method for thermally adhering the above-mentioned type of glass tape, which does not cause the tape to become thin or cut.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an opening in a metal cylindrical body in which a plastic tape is thermally bonded surrounding the outer peripheral surface leaving an outwardly extending protrusion. A method of thermally bonding the protruding portion to the end face and inner peripheral surface of the end portion, the protruding portion being bent approximately radially inward, and the base of the protruding portion being brought into contact with the entire surface of the end face, Next, a core having an elastic sleeve whose outer diameter is smaller than the inner diameter of the open end is inserted into the open end, the protruding portion is folded back, and the elastic sleeve is pressed in the axial direction, so that the inner diameter is expanding outward and pressing the folded protruding portion against the inner circumferential surface;
In the suppressed state, the open end of the metal cylinder is heated to a temperature higher than the temperature at which the plastic can be thermally bonded, and the protruding portion is thermally bonded to the end surface and the inner peripheral surface. This article provides a complete method for thermally bonding glass tape.

(Example) The present invention will be described below with reference to the drawings.

In FIG. 2, IO is a metal cylinder and lOa is an open end. In this specification, a metal cylindrical body is a cylindrical body having a pair of opposing open ends (a cylindrical body without side seams,
In addition to forming a cup-shaped cylinder with a bottom, such as the lower can 3 shown in FIG. 1, or a shoulder 2b and a curled part 2cl, as in the upper can 2, It also includes a cylindrical body having a narrow opening 2c.

The metal forming the cut metal cylinder also includes tin-plated steel plate, tin-free steel (electrolytic chromic acid treated deck), aluminum (alloy) plate, and other arbitrary metals or alloys.

The open end 10a of the metal cylindrical body 10 in FIG. 2 corresponds to the open end 3a of the lower can 3 in FIG. It becomes. Although not shown, an anticorrosion coating film (preferably excellent in thermal adhesion to the plastic material 7'll described later) is formed on the inner surface. The outer surface, especially the outer peripheral surface 1 of the opening end
If necessary, a primer layer (not shown) having excellent thermal adhesion with the plastic tape 11 is formed on 0a3. Note that the end surface of the opening end 10a] Oa.

are usually left cut so that the metal is exposed.

A plastic tape 11 is thermally bonded along the entire circumference, surrounding the outer circumferential surface 10a3' of the open end 10a, and a portion of the plastic tape 11 is not thermally bonded and extends outward to form the protruding portion 11a. It becomes. Plastics forming the plastic tape 11 include modified linear polyester, nylon 11 or nylon 12, or acid-modified polyolefin, which has a relatively low melting point or softening point.
A thermoplastic plastic having a polar group is exemplified.

Thermal bonding of the plastic tape 11 surrounding the outer circumferential surface 10a3i is performed by, for example, as previously proposed by the present inventors, the outer circumferential surface 10 is held on the circumferential surface of an adhesive roll by vacuum suction.
A piece of plastic tape with a length substantially equal to the circumference of A3 is heated to a temperature that allows thermal bonding, and the open end 10ai is internally supported by a mandrel, while rotating at the same circumferential speed as the adhesive roll. This is done by moving it onto the outer circumferential surface 1Oa3 under pressure.

By inserting the open end 10a into the die 12 shown in FIG. 3, the open end 10a is bent inward in the radial direction so that the base 11a of the protruding portion 11a abuts the entire surface of the end surface 10a1. The die 12 has an open end insertion hole 13 (
(hereinafter referred to as the opening end side hole), a stepped portion 14 connected to the opening end side hole 13 and extending radially inward, and a hole for inserting a core 16 (see Fig. 4) connected to the stepped portion 14. Part 15
(hereinafter referred to as core side hole).

The opening end side hole portion 13 has a truncated conical guide surface 13a and a short cylindrical guide surface 13bi, and a short cylindrical guide surface 13b.
The inner diameter of the open end 10a is D11, and the thickness of the plastic tape 11 is t(!: Then, (D+ +2t)
The opening end 10a, in which the plastic chip f11 is thermally bonded to the outer peripheral surface 10a3, is set to be slightly larger than the opening end 10a.

The radial width of the stepped portion 14 is determined to be substantially equal to the sum of the thickness of the open end portion 10a and the thickness 1) of the plastic tape 11. Therefore, when the open end 10a is inserted into the die 12 through the open end side hole 13, the protruding part 11a is bent approximately radially inward when it hits the stepped part 14, and the base 11a of the protruding part 11a is It is bonded between the stepped portion 14 and the end surface 10a1.

The core side hole portion 15 has a short cylindrical guide surface 15a and a frusto-conical guide surface 15bt for guiding the core 16 connected to the stepped portion 14. The inner diameter of the short circular guide surface 15a is substantially equal to the inner diameter of the open end 10a.

The die 12 is approached near the short cylindrical guide surface 13b,
A high-frequency induction heating coil 17 (hereinafter referred to as a heating coil) is built in surrounding the heating coil 17.
The open end 10a is fixed with a plastic tee 7'll.
It is possible to heat the plastic at a temperature higher than the temperature at which it can be thermally bonded (i.e., higher than the melting point or softening point) of the plastic that forms it. Therefore, the die 12 is not subjected to induction heating and is made of a material having strength and heat resistance, such as ceramics, Bakelite, fluororesin, or the like. Note that 18 is a magnetic core made of a high magnetic permeability material, for example, ferrite.

As shown in FIG. 4, the core 16 has a rigid core portion 16a1.
Cylindrical elastic sleeve 16b made of heat-resistant elastic rubber
It is equipped with Also, a hollow shaft 19 fixed to the core portion 16a
A pressing tool 21 having an annular protrusion 21a'i for pressing the end surface 16bl of the sleeve 16b is provided at the tip of the shaft 2o that is inserted through the sleeve 16b.

The outer diameter d of the sleeve 16b is preferably determined to be within a range that satisfies the following formula (11), more preferably within a range that satisfies formula (2).

D) d) D-2t-α (1) D-2t's d) D-2 -α It is usually a constant within the range of 0.05 to 0.3 mm.

When the outer diameter d becomes 0 or more, the protruding part 1iak of the tape
When inserting the core 16 into the opening end 10a while folding it back, a large axial tension is applied to the protruding portion 11aK, and during thermal bonding, the protruding portion 11a is attached to the end surface 10a.
There is a risk that the wall of the first coat may become thin or cut.

Furthermore, the sleeve is likely to wear out during repeated use.

On the other hand, if the outer diameter becomes less than (D-2 - α), the pressing tool 21
Even if the sleeve 16bk is pressed in the axial direction and expanded radially outward, sufficient pressing force cannot be applied to the protruding portion 11a, and the protruding portion 11a after thermal bonding is
Wrinkles and bubbles are likely to occur.

The elastic coil forming the sleeve 16b is preferably one having excellent heat resistance, abrasion resistance, and releasability from the melted or softened plastic material 7'll, such as a fluorine coil or a silicone coil. That hard rubber (
A) is preferably 40 to 80 degrees, more preferably 50 to 7 degrees.
0 degree is more preferable.

Thermal bonding is performed using the above-mentioned apparatus as follows.

The open end 10a'i is inserted into the die 12, and the protruding part 1
1'a is bent into a radial inner push 1 so that its base 11a+ abuts the end surface 1oaf, and then the hollow part 19 is inserted into a ringing device (for example, a cam mechanism), not shown.
5, the core 16 is inserted into the opening end 10a together with the suppressor 21, and the protruding portion 118 is folded back.

Immediately move the shaft 20 to the right in the figure by a drive device (for example, an air cylinder) not shown, and press the pressing tool 2.
1 of the annular protrusion 21, the end surface 1 of the sleeve 16b
6bti with a predetermined force to expand the sleeve 16b radially outward and press the folded protruding portion 11a against the inner circumferential surface 10a2 of the open end 10a, as shown in FIG. .

When the heating coil 17 is energized at the same time, the open end 10
a is induction heated to a temperature higher than the temperature at which the plastic can be thermally bonded, and the base 11a of the protruding portion 11a is the end surface 10a.
1, the folded protruding portion 11a is located on the inner peripheral surface 1.
0a2, the thermal bonding part is placed under pressure.

In this case, the heating temperature is changed by the input current to the heating coil 17, and the pressing force against the folded protruding part 11a is changed by the force applied to the gift 20, so that the thickness of the plastic tape 11 is substantially reduced during thermal bonding. It can be easily controlled to the extent that it does not fluctuate. After thermal bonding, the heating coil 17 is deenergized and the glass tape 11 is cooled and solidified, after which the pressing tool 21 is returned to its original position and the core 16 and metal cylinder 10 are extracted from the die 12.

When thermal bonding is performed continuously, the surface 16b of the sleeve is heated and the diameter changes, and the resin at the cant edge may be thinned due to excessive compression. It is preferable to prevent the temperature rise on the surface of the sleeve by using a device or the like.

The present invention is not limited to the above examples, and for example, the sleeve 16b is
z (FIG. 5) to expand radially.

(Effects of the Invention) According to the present invention, even if the outer diameter of the elastic sleeve of the core changes slightly due to changes in temperature, etc., the predetermined force can be maintained by adjusting the axial force applied to the elastic sleeve. Since the protruding portion of the folded plastic tape can be thermally bonded by the pressing force, it is possible to obtain a thermally bonded portion free from defects such as bubbles and wrinkles.

In addition, since the frictional force when inserting the elastic sleeve into the open end can be minimized or zero, there is less wear and tear on the sleeve, and the axial tension applied to the folded protrusion is also small. Therefore, it is possible to easily prevent the folded protruding portion from becoming thin or being cut at the corner portion.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an example of a metal container in which a metal cylinder to which a plastic tape is thermally bonded by the method of the present invention is assembled as a lower can body, and FIG. 1. A vertical cross-sectional view of a main part of a metal cylindrical body with a plastic tape thermally bonded to the outer circumferential surface of the open end. FIG. 4th longitudinal cross-sectional view showing a state in which the portion is bent approximately radially inward;
The figure is a longitudinal cross-sectional view of an example of a core used to carry out the method of the present invention, and FIG. 5 shows the core shown in FIG. 4 inserted into the open end of the metal cylinder shown in FIG. 3. FIG. 6 is a longitudinal sectional view showing a state in which the sleeve of the core is pressed in the axial direction to perform thermal bonding. 10... Metal cylindrical body, 10a... Open end '1 10
a... End face, 10a2... Inner peripheral surface, 10a3...
Surrounding the evening, 11...Plastic tape, 11a...
・Protrusion part, 11a1...base, 16...core,
16b... Elastic sleeve, 17... High-frequency induction heating coil, 21... Pressing tool 0, Patent applicant: Akira Kishimoto, Patent attorney: Etsube Shuto ・1.11〕□, 2 First illustration ] No. 4 (￥I and 10 No. 5, No. 6 (branch)

Claims (1)

[Claims] (1) The protruding parts are thermally bonded to the end face and inner circumferential surface of the open end of the metal cylindrical body, which is heat-bonded by surrounding the outer circumferential surface, leaving an outwardly extending protruding part. The method comprises: bending the protruding portion approximately radially inward and bringing the base of the protruding portion into contact with the entire surface of the end surface;
Next, a core having an elastic sleeve whose outer diameter is smaller than the inner diameter of the open end is inserted into the opening, the protruding portion is folded back, and the elastic sleeve is pressed in the axial direction. The protruding portion expanded radially outward and folded is pressed against the inner circumferential surface, and in the suppressed state, the open end is heated to a temperature higher than the temperature at which the plastic can be thermally bonded to close the protruding portion. A method for thermally bonding a silk tape to an open end of an integral metal cylinder, the method comprising: C thermally bonding a silicone tape to the end surface and the inner circumferential surface.