JP2000142605A - Ultrasonic sealing method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sealing a tube container wherein when a bottom opening end rim of the tube container formed of a thermoplastic resin is sealed by welding, influence of stress or strain due to thermal expansion of the tube container is reduced and defects such as burrs and pinholes are less likely to occur. SOLUTION: When a container opening end rim 5a of a tube container 5 formed of a thermoplastic resin is held by a horn 13 and an anvil 14 of an ultrasonic vibrator 3 for sealing the container opening end rim 5a of the container 5 by frictional heat due to ultrasonic vibration, the end rim 5a of the container 5 is preheated, and the preheated end rim 5a is held by the horn 13 and the anvil 14 for welding by ultrasonic vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing method for sealing a bottom opening edge of a tube container made of a thermoplastic resin by welding by frictional heat generated by ultrasonic vibration. The present invention relates to a tube container sealing method for sealing the opening edge after preheating the edge.

[0002]

2. Description of the Related Art Conventionally, in welding and sealing the bottom opening edge of a tube container formed of a thermoplastic resin by ultrasonic vibration, an ultrasonic sealing method for a tube container proposed in Japanese Patent Application Laid-Open No. 3-49931 is disclosed. It has been known.

[0003] In the sealing method, the opening edge is preliminarily clamped and flattened by a pair of conveyor belts, and a horn that generates ultrasonic vibrations in that state and an anvil that is a stator facing the horn are used. Hold the opening edge,
A method of generating frictional heat between a horn and an anvil and the opening edge by ultrasonic vibration generated from a horn to weld and seal the opening edge.

In this sealing method, the opening edge is flattened in advance, and sealing is performed as it is. By sandwiching the opening edge flat in advance, stress or distortion generated in the sealing portion easily escapes to the periphery. Therefore, it is possible to reduce the occurrence of defects such as cavities (burrs) generated on the boundary between the sealed portion and the non-sealed portion in the sealed tube container, and pin holes generated in the sealed portion. This is a method for sealing a tube container.

[0005]

By the way, when the bottom opening edge of the tube container is sealed by welding, the tube container behaves in such a manner as to expand in both the length direction and the trunk direction. This is considered to be due to thermal expansion due to heat applied to the tube container when welding the opening edge of the tube container.

Although the above-mentioned sealing method makes it difficult to generate defects such as burrs and pinholes, it generates heat such that the opening edge is welded to the opening edge of the tube container at room temperature. However, it has not been possible to sufficiently cope with stress and strain caused by thermal expansion.

The present invention has been made in view of the above situation,
An object of the present invention is to reduce the influence of stress and strain caused by thermal expansion of a tube container when sealing the bottom opening edge of a tube container formed of a thermoplastic resin by welding, and to reduce the effects of burrs and pinholes. An object of the present invention is to provide a method for sealing a tube container, which makes defects less likely to occur.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a sealing method and a sealing device for ultrasonically sealing an edge of a bottom opening of a tube container. I have.

That is, the bottom opening edge of a tube container formed of a thermoplastic resin is sandwiched between a horn and an anvil of an ultrasonic vibrator, and the bottom opening edge of the tube container is frictionally heated by ultrasonic vibration. In sealing the seal,
An ultrasonic sealing method for a tube container in which a bottom opening edge of the tube container is preheated, and the preheated opening edge is sandwiched between the horn and an anvil and welded by ultrasonic vibration.

A sealing device according to the present invention comprises a preheating device for heating an edge of a bottom opening of a tube container, a horn for generating ultrasonic vibration, and an anvil as a stator facing the horn. And an ultrasonic vibration device installed so as to sandwich the opening edge.

Further, the preheating device is a first blower that blows warm air, and a tubular body having a closed base end, the blower being provided inside a base end of the tubular body. A straight body portion, a hollow tapered portion installed at the tip of the first straight body portion and converging from the diameter of the first straight body portion to a smaller diameter in the tip direction, and convergence of the tapered portion. A second straight body having a diameter equal to the convergent end, a bar protruding from the front end of the second straight body in the front direction, and a tip of the bar. A preheating device comprising a plate-shaped member installed and fixed perpendicular to the length direction of the bar is suitable for heating the opening edge.

In the preheating step of preheating the bottom opening edge of the tube container formed of a thermoplastic resin, a certain amount of heat is applied in the length direction or the trunk direction of the tube container by heating the bottom opening edge of the tube container. The step may be a step of generating stress or strain due to expansion in advance. The heating performed here is preferably such that heat is applied to the bottom opening edge so as not to change the shape of the bottom opening edge of the tube container to be heated, and it is more preferable that the opening edge is uniformly heated. .

As the preheating step, a method of heating by bringing a heat source such as a heater into contact with the opening edge or a method of heating without contacting a heat source with the opening edge can be considered. The latter is a tube. The bottom opening edge of the container can be heated evenly, and even if the filling filled in the tube container adheres to the vicinity of the opening of the tube container, there is little possibility of contaminating the heat source, the tube container and the filling. preferable.

Preferably, the preheating step is performed immediately before the sealing step of sealing the opening edge by ultrasonic vibration. However, if the step of sandwiching the opening edge and flattening is performed before the sealing step. It is further preferable that stress and strain generated by thermal expansion can escape to the periphery of the opening edge.

In the sealing step, a method of sealing the opening edge by the ultrasonic vibration known in the prior art and the like can be used. Further, as shown in JP-A-3-49931, when sealing is performed by ultrasonic vibration in a state where the opening edge is sandwiched between a pair of conveyor belts, the occurrence of the burrs and pinholes can be reduced, In addition to reducing sealing sound, stabilizing sealing strength and sealing time,
This is preferable because scattering of the tube resin during sealing is reduced.

The above-mentioned preheating device has the above-described configuration, and enters the inside of the tube container from the bottom opening edge of the tube container, and heats the opening edge from the inside by blowing heated air. can do. The shape and size of the preheating device are determined by the shape and size of the tube container to be heated.In general, if the vertical cross section of the preheating device in the longitudinal direction of the preheating device is circular, the opening edge is uniform. It is suitable for heating to.

The blowing device in the preheating device may be a device for blowing air heated by a heat source. The air may be heated air that is blown after being heated to a predetermined temperature, or may be heated air that passes through a heat source in the process of being blown and is thereby heated to a predetermined temperature. The temperature of the heated air is determined by the resin compound forming the tube container and the filling material filled in the tube container, but is generally preferably 80 to 100 ° C.

The first straight body preferably has the blower disposed on the inner base end side of the straight body. When the base is closed, heated air blown from the blower is preferably provided. Is more preferably blown in one direction toward the tip of the straight body. The first straight body preferably has a larger diameter than the bottom opening edge of the tube container to be heated.

The diameter of the converging end of the tapered portion depends on the diameter of the opening edge, and is preferably smaller than the opening edge. In addition, if the outer peripheral surface of the tapered portion is provided with a film made of a resin having excellent heat resistance, such as a fluororesin, and a small moisture permeability, the filler adhering to the periphery of the opening edge may be filled. It is more preferable because it becomes difficult to adhere to the outer peripheral surface of the tapered portion, and cleaning when it adheres becomes easy.

The second straight body portion is a straight body portion installed from the convergent end of the tapered portion toward the distal end, and the diameter of the second straight body portion is determined by the diameter of the convergent end. It is preferable to provide a resin compound film having excellent heat resistance and low moisture permeability similarly to the tapered portion on the outer peripheral surface of the second straight body portion.

The bar is a means for connecting the second straight body and the plate-like body, and is protruded from the tip of the second straight body to the tip direction. A heated air passage hole is formed between the tip and the plate. A single bar may be provided, but it is preferable that about two or three bars be provided at target positions with respect to the center axis of the second straight body. On the outer surface of the bar,
Similar to the tapered portion and the second straight body portion, it is preferable to provide a resin compound film having excellent heat resistance and small moisture permeability.

The plate-like body is supported by the bar in a direction perpendicular to the central axis direction of the second straight body. The shape of the plate-like body is vertical to the second straight body. It is preferable that the shape is the same as the shape of the cross section, and if the size is slightly larger than the shape of the vertical cross section, the heated air flows along the surface direction of the plate-like body, and It is more preferable because the periphery can be uniformly heated. The outer surface of the plate-like body also has the tapered portion, the second straight body portion,
Like the rod and the bar, it is preferable to provide a film of a resin compound having excellent heat resistance and low moisture permeability.

When the opening edge is heated by the preheating device having the above-described configuration, the heating time of the opening edge by the preheating device depends on the thickness and properties of the thermoplastic resin forming the tube container and the heating air. Generally, the temperature of the heated air is 80 to 100 ° C.
In this case, the time is about 0.5 to 1 second. Under such a condition, it is sufficient to heat the opening edge and does not deteriorate the filling in the tube container.

The ultrasonic vibration device can use a conventional technique. A horn, which is a vibrator for generating ultrasonic vibration, and an anvil, which is a stator facing the horn, have an opening edge. It can be an ultrasonic vibration device installed so as to be sandwiched.

The ultrasonic vibration device includes a longitudinal vibration type in which ultrasonic vibration is applied in a direction perpendicular to the welding surface of the opening edge,
A lateral vibration type in which ultrasonic vibration is applied in a direction parallel to the welding surface, an oblique vibration type in which ultrasonic vibration is applied in an oblique direction to the welding surface, and the like are known. The oblique vibration type ultrasonic vibration device is preferable.

When the tube container whose opening edge is heated by the preheating device is transported from the preheating device to the ultrasonic vibrator, the tube container is transported via a pair of transport belts that sandwich and flatten the opening edge. Then, it is preferable that the stress and strain generated in the tube container by heating can be released to the periphery of the opening edge, so that the sealing by the ultrasonic vibration device is performed while the opening edge is sandwiched by the conveyor belt. It is more preferable to provide a conveyor belt.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows an ultrasonic sealing device according to an embodiment of the present invention.

The ultrasonic sealing device according to the present embodiment includes a preheating device 1 which enters the inside of the tube container 5 from the container opening edge 5a of the tube container 5 and heats the container opening edge 5a, and a container opening edge 5a. And a pair of transport belts 2 for holding and flattening the container, and an ultrasonic vibration device 3 for sandwiching the container opening edge 5a held by the transport belt 2 and generating ultrasonic vibration.

A belt conveyor 4 for moving the tube container 5 to a work position of each device is provided immediately below the preheating device 1, the conveyor belt 2, and the ultrasonic vibration device 3. The tube container 5 is held by a holder 6 that holds the tube container 5 in an inverted state such that a container opening edge 5a corresponding to the bottom of the tube container 5 faces upward.
Along with the belt conveyor 4. In addition, the tube container 5 is formed of polyethylene which is a thermoplastic resin.

As shown in FIG. 2, the preheating device 1 has a blowing device 7 for blowing heated air, a diameter of 44 mm and a height of 30 mm.
A first straight body portion 8 that closes the base end of a cylindrical body having a diameter of 2 mm and the blower 7 is installed on the inner base end side, and a length of 40 mm that converges from the front end of the first straight body portion 8 toward the front end. The tapered portion 9, a second straight body portion 10 having a diameter of 8 mm and a length of 20 mm installed from the converging end of the tapered portion 9 toward the front end, and a length from the front end of the second straight body portion 10. Two rods 11 protruding toward the distal end at 10 mm, and a 2 mm-thick disc 1 installed at the distal end of the rod 11 in a direction perpendicular to the longitudinal direction of the rod 11
2

The surface of the disk 12 on the side of the bar 11 is a circle having a diameter of 8.5 mm, and the surface of the disk 12 on the side of the bar 11 is slightly larger than the diameter of the second straight body 10. have. The surface on the tip end side of the disk 12 is a slightly smaller circular shape than the surface on the side of the bar 11, and the side surface of the disk 12 is
Slightly converges toward the tip. Outer peripheral surfaces of the tapered portion 9 and the second straight body portion 10 and the bar 11 and the disc 12
Is subjected to a fluororesin processing.

The ultrasonic vibration device 3 is an oblique vibration type ultrasonic vibration device, and as shown in FIG. 3, a horn 13 which is a vibrator for generating ultrasonic vibration and a ultrasonic vibration device for generating ultrasonic vibration. Has an anvil 14 as a stator. The horn 13 is fixed at a certain position, the anvil 14 is installed so as to be movable in the horizontal direction as indicated by the arrow in the figure, and the horn 13 and the anvil 14 are installed so as to be able to pinch the container opening edge 5a. ing.

Next, an ultrasonic sealing method using the ultrasonic sealing device according to the present embodiment will be described. <Preheating Step> The tube container 5 moves to just below the preheating device 1 while being held by the holder 6 on the belt conveyor 4. When the tube container 5 moves to just below the preheating device 1, the preheating device 1 enters the tube container 5 from the container opening edge 5a as shown in FIG. At this time, the preheating device 1 forms a gap between the outer peripheral surface of the tapered portion 9 and the container opening edge 5a, and prevents the filling material filled in the tube container 5 from coming into contact with the disk 12. It enters the tube container 5.

The second straight body portion 10, the bar 11, and the disk 12 located on the tip side from the tapered portion 9 are formed in the tube container 5, which may occur when the tube container 5 is filled with a highly viscous filler. Although there is a possibility of contact with the filler adhering to the inner wall of the tube container 5 due to dripping to the inner wall or the like, the above-mentioned constituent members are hardly adhered to the filler because the outer surface is subjected to fluororesin processing, In addition, even if they adhere, cleaning is easy.

When the preheating device 1 enters the inside of the tube container 5 from the container opening edge 5a, the blowing device 7
Heated air at 0 ° C. is blown. The heated air is blown in the direction of the arrow in FIG. That is, the heated air blown from the blower 7 is supplied to the first straight body portion 8, the tapered portion 9,
Then, it passes through the inside of the second straight body portion 10 and is blocked by the disk 12 in the flow direction.

The heated air whose flow direction has been interrupted by the disk 12 is supplied to the second straight body 10 by the rod 11.
After flowing out of the gap created between the disk 12 and the disk 12 and flowing in the surface direction of the disk 12, it collides with the inner wall of the tube container 5,
Further, it rises along the inner wall of the tube container 5 and flows out of the tube container 5 through a gap formed between the container opening edge 5a and the outer peripheral surface of the tapered portion 9.

Since the disk 12 is fixed so as to form a surface perpendicular to the length direction of the bar 11, the heated air flows out uniformly to the inner wall of the tube container 5. Therefore, the heated air rising along the inner wall of the tube container 5 also flows uniformly on the inner wall of the tube container 5 up to the container opening edge 5a. Is heated uniformly. The time during which the heated air is blown from the blower 7 is 0,0.
It is about 5 to 1 second.

When the heating of the container opening edge 5a by the heated air is completed, the preheating device 1 moves upward from the container opening edge 5a and returns to the position before the preheating step. The tube container 5 having the heated container opening edge 5 a is conveyed to the conveyor belt 2 by the belt conveyor 4, and the container opening edge 5 a is clamped by the conveyor belt 2. Tube container 5 sandwiched by conveyor belt 2 and having container opening edge 5a flattened
Is transported to the ultrasonic vibration device 3 by the transport belt 2 with the container opening edge 5a held therebetween.

<Ultrasonic Sealing Step> The horn 13 and the anvil 14 of the ultrasonic vibrating device 3 are provided with a gap into which the container opening edge 5a of the tube container 5 conveyed by the conveyor belt 2 can be directly inserted. . Conveyor belt 2
Tube container 5 whose container opening edge 5a is sandwiched by
Is transported between the horn 13 and the anvil 14. When the container opening edge 5a is conveyed between the horn 13 and the anvil 14, the horn 13 and the anvil 14
, So as to sandwich the container opening edge 5a in the horizontal direction.

When the container opening edge 5a is sandwiched by the horn 13 and the anvil 14, the horn 13 generates ultrasonic vibration in an oblique direction with respect to the container opening edge 5a sandwiched. The container opening edge 5a is welded between the container opening edge 5a and the horn 13 and the anvil 14 by frictional heat generated by the ultrasonic vibration, and the container opening edge 5a is sealed.

The tube container 5 in which the container opening edge 5a is welded and sealed is carried out of the ultrasonic vibration device 3 by the belt conveyor 4 and subjected to post-processing such as R-cut of the seal portion, appearance inspection, etc. Become.

[0042]

According to the ultrasonic sealing method of the present invention, a preheating step of preheating the bottom opening edge is performed before the ultrasonic sealing step of sealing the bottom opening edge of the tube container formed of a thermoplastic resin. This makes it possible to reduce the stress and strain generated at and around the bottom opening edge due to the thermal expansion accompanying the sealing, and as a result, the sealing method can further reduce defects such as burrs and pinholes.

Since the bottom opening edge of the tube container is preheated in the preheating step, the time of ultrasonic vibration required for sealing in the ultrasonic sealing step can be shortened. Furthermore, by selecting appropriate preheating conditions for the material and shape of the tube container whose bottom opening edge is heated in the preheating step, the above heating can be performed in a short time, and the quality can be reduced without lowering the productivity. This is a sealing method capable of sealing the bottom opening edge in a good tube container.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an ultrasonic sealing device according to an embodiment of the present invention.

FIG. 2 is a side view showing a preheating apparatus according to one embodiment of the present invention.

FIG. 3 is a schematic diagram showing an ultrasonic vibration device according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a preheating step by a preheating device according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preheating device 2 Conveying belt 3 Ultrasonic vibration device 4 Belt conveyor 5 Tube container 5a Container opening edge 6 Holder 7 Blower 8 First straight body 9 Tapered part 10 Second straight body 11 Bar 12 Disk 13 Horn 14 Anvil

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Minoru Ohata 6-48, Yayoi-cho, Shizuoka-shi, Shizuoka Pref. DA03 EA06 FA05 FA16 GA11 HA02 HA08

Claims (3)

[Claims] 1. An edge of a bottom opening of a tube container formed of a thermoplastic resin is sandwiched between a horn and an anvil of an ultrasonic vibrator, and the bottom opening edge of the tube container is frictionally heated by ultrasonic vibration. An ultrasonic sealing method for a tube container, wherein a sealing edge is preheated at the bottom opening edge of the tube container, and the preheated opening edge is sandwiched between the horn and the anvil and welded by ultrasonic vibration. 2. A preheating device for heating an opening edge of a bottom portion of a tube container, a horn for generating ultrasonic vibration, and an anvil serving as a stator facing the horn, wherein the horn and the anvil are connected to the opening edge. An ultrasonic sealing device for a tube container, comprising: an ultrasonic vibrating device installed so as to sandwich the tube container. 3. A first blowing device for blowing warm air, wherein the preheating device is a tubular body having a closed base end, and the blower device is provided inside a base end portion of the tubular body. A straight body portion, a hollow tapered portion installed at the tip of the first straight body portion and converging from the diameter of the first straight body portion to a smaller diameter in the tip direction, and convergence of the tapered portion. A second straight body having a diameter equal to the converging end, a second straight body being installed from the end to the front end, a bar protruding from the front end of the second straight body toward the front, and a front end of the bar. The preheating apparatus according to claim 2, further comprising: a plate-like body that is installed and fixed vertically to a length direction of the bar.