Ultrasonic welding device and welding method for spouts

Abstract

To provide a welding technique for ultrasonically welding a plug without forming a depression on an outer surface of a container, preventing seal slippage and pinhole, and reducing variation in a projection amount of the plug to the outer surface of the container.SOLUTION: Among the ultrasonic horn and the anvil, when the one placed on an outside of a container is an outer surface side welding tool 31 and the one placed on an inside of the container is an inner surface side welding tool 41, a container blank-side surface of the outer surface side welding tool 31 is flat, a flange-side surface of the inner surface side welding tool 41 is ring-shaped, and a ring-shaped convex part 41a is provided on this ring-shaped surface over the entire periphery. In addition, a pedestal 51 for supporting a pouring cylinder of a plug is provided in a region surrounded by a ring-shaped surface of the inner surface side welding tool 41, and this pedestal 51 is independent from the inner surface side welding tool.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for ultrasonically welding a closure to a container blank. [Background technology]

[0002] Containers that hold liquid contents and have a stopper attached to the top from which the liquid contents are poured are well known. For example, containers with a stopper attached to the top of a liquid paper container, commonly known as a milk carton, are widely used.

[0003] The technology for ultrasonically welding a spout to a cylindrical blank for a liquid-storing paper container is described, for example, in Patent Document 1 and Patent Document 2. Fig. 10 is an explanatory cross-sectional view for explaining the main part.

[0004] The container blank 10 used in this technology has a surface on the inner side of the container that can be ultrasonically welded to the stopper 20. The blank 10 for liquid paper containers usually has paper as the base material, with a thermoplastic resin coating on both the inner and outer surfaces, and the stopper 20 can be ultrasonically welded to the thermoplastic resin coating on the inner surface.

[0005] Furthermore, a through hole is provided in advance in the blank 10, and the dispensing tube 21 of the plug 20 is inserted into this through hole.

[0006] On the other hand, the stopper 20 is configured to include a pouring tube 21 and a flange 22. The pouring tube 21 is used to pour the liquid content contained in the container out of the container, and has a communication hole in its center that connects the inside and outside of the container. On the other hand, the flange 22 is used to weld and fix the stopper 20 to the inside surface of the container, and as shown in the figure, is located around one end of the pouring tube 21 and is configured integrally with this pouring tube 21. As described above, the pouring tube 21 is inserted into the through hole of the blank 10, and the flange 22 is positioned around the through hole so as to abut against the inside surface of the container of the blank 10.

[0007] Then, when the flange 22 abuts against the inner surface of the blank 10, they are clamped between the ultrasonic horn 36 and the anvil 46 and pressed together while irradiating ultrasonic waves from the ultrasonic horn 36, thereby ultrasonically welding the plug 20 to the thermoplastic resin coating on the inner surface of the blank 10. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-30382 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-311850 Summary of the Invention [Problem to be solved by the invention]

[0009] As shown in the drawings, in the techniques described in Patent Documents 1 and 2, an ultrasonic horn 36 is disposed on the outer surface of a container, and an anvil 46 is disposed on the inner surface of the container. A ring-shaped protrusion 36a is provided on the surface of the ultrasonic horn 36 facing the blank 10. During ultrasonic welding, this ring-shaped protrusion 36a presses the blank 10 against the outer surface of the container, concentrating ultrasonic waves. Meanwhile, the surface of the anvil 46 facing the stopper 20 is flat, and supports not only the flange 22 of the stopper 20, but also the dispensing tube 21 together with the flange 22. When the stopper 20 is ultrasonically welded using such an ultrasonic horn 36 and anvil 46, a ring-shaped depression surrounding the stopper is left on the outer surface of the container, corresponding to the ring-shaped protrusion 36a.

[0010] This ring-shaped depression is particularly problematic when the container is used in a wet environment, such as when the container is used in a bathroom to store shampoo or conditioner. In this case, the contents poured through the spout 20 adhere to the outer surface of the container and, moreover, get into the depression, making it difficult to remove.

[0011] Therefore, a first object of the present invention is to provide a welding device and a welding method that can ultrasonically weld a stopper without creating a depression in the outer surface of a container.

[0012] Of course, in the welding apparatus and welding method of the present invention, seal omissions must not occur, and pinholes due to welding must not occur.

[0013] Furthermore, if the stopper sinks into the container during welding, causing variations in the length of the stopper protruding from the outside of the container, this can cause variations in the pouring of the contents, making the container less user-friendly.Furthermore, the cap that seals the stopper can become tilted, making it impossible to seal.

[0014] The present invention has been made in light of these circumstances, and in addition to its primary objective of ultrasonically welding a stopper without creating a depression on the outer surface of a container, it also aims to provide a welding device and a welding method that do not cause missing seals or pinholes, and that also have little variation in the amount of stopper protruding from the outer surface of the container. [Means for solving the problem]

[0015] That is, the invention described in claim 1 is an apparatus for ultrasonically welding a stopper to a container blank, The container blank is provided with a through hole, and the stopper is a pouring tube for pouring out the contents. pouring tube and a flange provided around the through hole, and the spout tube of the spout is inserted into the through hole, and the flange is fastened to the through hole. of The device clamps the flange and the blank at the abutting portion between an ultrasonic horn and an anvil while the flange is in contact with the inner surface of the surrounding container blank, and irradiates ultrasonic waves from the ultrasonic horn to weld the flange of the plug to the inner surface of the container blank, When the ultrasonic horn and the anvil, which are arranged on the outer surface side of the container blank, are referred to as an outer surface welding tool, and the ultrasonic horn and the anvil, which are arranged on the inner surface side of the container blank, are referred to as an inner surface welding tool, The surface of the outer welding tool on the container blank side teeth, It is flat and No irregularities are formed in the portion overlapping with the flange, On the other hand, the surface of the inner welding tool on the flange side is ring-shaped, and a ring-shaped protrusion is provided on the ring-shaped surface around the entire circumference, Furthermore, a base for supporting the pouring tube of the spout is provided in an area surrounded by the ring-shaped surface of the inner surface welding tool, Moreover, this ultrasonic welding device for a plug is characterized in that the base is independent from the inner surface welding tool.

[0016] In addition, the pouring tube side of the base of The surface may be provided with irregularities.

[0017] The ring-shaped surface of the inner welding tool is located on the pouring tube side of the base. of The surface may be closer to the plug than the surface, for example, 0.2 mm.

[0018] Also, a biasing component may be provided that biases the base toward the dispensing tube of the plug.

[0019] Then, the ultrasonic welding device can be used to ultrasonically weld the stopper to the container blank. [Effects of the Invention]

[0020] According to the present invention, the surface of the outer welding tool placed on the outer surface side of the container blank is flat, so even if this flat surface is pressed against the blank, no depression is created on the outer surface of the container.

[0021] Furthermore, the inner surface welding tool arranged on the inner surface of the container blank is provided with a ring-shaped protrusion around the entire circumference, and this ring-shaped protrusion is pressed against the inner surface of the container blank, so the stopper can be welded liquid-tightly without causing the seal to come loose.

[0022] In addition, a base for supporting the spout of the stopper is provided in the area surrounded by the ring-shaped surface of the inner welding tool, which helps to reduce variations in the amount of the stopper protruding toward the outer surface of the container. Moreover, because this base is independent of the inner welding tool, it adequately supports the spout of the stopper during welding, preventing pinholes from forming.

[0023] Furthermore, because the base that supports the dispensing tube does not absorb ultrasound, the stopper can become hot in parts, causing it to break off into string-like pieces, creating foreign matter. However, if the surface of the base facing the dispensing tube is uneven, this type of foreign matter will not be created. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 relates to a first embodiment of the present invention, and FIG. 1(a) is a cross-sectional explanatory view of a main part showing welding using an ultrasonic welding device according to the first embodiment, FIG. 1(b) is an enlarged cross-sectional explanatory view showing the relationship between the ring-shaped surface of the inner welding tool and the surface of the base facing the pouring tube, and FIG. 1(c) is an enlarged plan view explanatory view showing the surface of the base facing the pouring tube. [Figure 2] FIG. 2 relates to a second embodiment of the present invention, and FIG. 2(a) is a cross-sectional explanatory view of the main part during welding using an ultrasonic welding device according to the second embodiment, and FIG. 2(b) is an enlarged cross-sectional explanatory view showing the relationship between the ring-shaped surface of the inner welding tool and the surface of the base on the pouring tube side. [Figure 3] FIG. 3 relates to a third embodiment of the present invention, and FIG. 3(a) is a cross-sectional explanatory diagram of the main parts during welding using an ultrasonic welding device according to the third embodiment, FIG. 3(b) is an enlarged cross-sectional explanatory diagram showing the relationship between the ring-shaped surface of the inner welding tool and the surface of the base facing the dispensing tube, and FIG. 3(c) is an enlarged plan view explanatory diagram showing the positional relationship between the surface of the base facing the dispensing tube and the urging component. [Figure 4] FIG. 4 relates to Comparative Example 2 and is an explanatory cross-sectional view of a main part showing welding using the ultrasonic welding device according to Comparative Example 2. [Figure 5] FIG. 5 relates to Comparative Example 3 and is an explanatory cross-sectional view of a main part showing welding using the ultrasonic welding device according to Comparative Example 3. [Figure 6]FIG. 6 is a development view showing a blank of the upper sheet of the liquid-discharging paper container used in each of the examples and comparative examples. [Figure 7] FIG. 7 is a development view showing a blank of the lower sheet of the liquid-discharging paper container used in each of the examples and comparative examples. [Figure 8] FIG. 8 is a perspective view showing the state in which the upper and lower sheets of the liquid-carrying paper containers used in the examples and comparative examples are stacked. [Figure 9] FIG. 9 is a perspective view showing the box-shaped liquid-holding paper container used in each of the examples and comparative examples. [Figure 10] FIG. 10 is an explanatory cross-sectional view of a main part showing welding using a conventional ultrasonic welding device. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0026] (First embodiment) FIG. 1 relates to a first embodiment of the present invention, and FIG. 1(a) is a cross-sectional explanatory view of a main part showing welding using an ultrasonic welding device according to the first embodiment, FIG. 1(b) is an enlarged cross-sectional explanatory view showing the relationship between the ring-shaped surface of the inner welding tool and the surface of the base facing the pouring tube, and FIG. 1(c) is an enlarged plan view explanatory view showing the surface of the base facing the pouring tube.

[0027] As shown in the figure, the ultrasonic welding apparatus A1 according to the present invention is an apparatus for ultrasonically welding a stopper 20 to a container blank 10. When using this apparatus A1, it is necessary to prepare the container blank 10 and the stopper 20, and further, it is necessary to supply the container blank 10 and the stopper 20 to this apparatus A1 in a predetermined positional relationship.

[0028] That is, first, the surface of the container blank 10 that will become the inner surface of the container must be able to weld the stopper 20. Generally, by laminating a plastic film on the surface that will become the inner surface of the container, it becomes possible to weld the stopper 20 to this inner surface.

[0029] The other layers may be made of any material, but it is desirable to use a blank based on paper, for example. It is also desirable to have a plastic coating on the outer surface of the container. Blanks laminated with various plastic coatings, metal foils, vapor-deposited films, etc., in addition to paper can be used. A typical example of metal foil is aluminum foil. Vapor-deposited films can be formed by vapor-depositing a thin film on a plastic film such as polyester film or polypropylene film as a vapor-deposited substrate, with a metal such as aluminum or an oxide such as aluminum oxide deposited on the surface. Of course, a printed pattern layer may also be included.

[0030] Examples of containers that use such blanks 10 include liquid paper containers commonly known as milk cartons. Alternatively, the liquid paper container described in JP 2019-026274 A may be used. The liquid paper container described in JP 2019-026274 A will be described later together with examples.

[0031] Next, this container blank 10 must be provided with a through-hole through which a dispensing tube 21 of a spout 20, which will be described later, can be inserted.

[0032] On the other hand, the spout 20 is configured to have a pouring tube 21 and a flange 22. Inside the pouring tube 21, a pouring passage is provided that connects the inside and outside of the container and enables the pouring of the liquid content. It is usually cylindrical. Note that a blocking part that closes this pouring passage before use may be provided. By providing a pull top or the like to this blocking part, it is possible to remove the blocking part and open the pouring passage when in use.

[0033] The flange 22 is welded to the inner surface of the container to fix the stopper 20. The flange 22 is provided around the end surface of the pouring tube 21 on the inner surface side of the container. As mentioned above, the pouring tube 21 is usually cylindrical, so its end surface is circular with a pouring passage in the center, and the flange 22 is ring-shaped and connected to the end surface of the pouring tube 21 on the inner surface side of the container and provided around it.

[0034] As shown in the figure, the dispensing tube 21 of the stopper 20 is inserted into the through-hole of the container blank 10 from the inside of the container, so that the flange 22 abuts against the inside of the container blank around the through-hole. The container blank 10 and the stopper 20 are supplied to the ultrasonic welding device A1 in this positional relationship. Note that the container blank 10 and the stopper 20 only need to have this positional relationship when they are welded, and do not need to have this positional relationship before being supplied to the ultrasonic welding device A1. For example, first, the container blank 10 is supplied to the ultrasonic welding device A1. Then, the plug 20 may be inserted into the through-hole from the inside surface of the container.

[0035] The ultrasonic welding apparatus A1 has an ultrasonic horn and an anvil that sandwich the flange 22 and the portion of the blank 10 that abuts against it, of the container blank 10 and the plug 20 that are positioned as described above. In addition to the ultrasonic horn and anvil, the ultrasonic welding apparatus A1 also has, as an essential component, a base that supports the dispensing tube of the plug.

[0036] The ultrasonic horn transmits ultrasonic waves to either the flange 22 or the portion of the blank 10 that contacts it, causing high-frequency vibrations, and heat generated by this high-frequency vibration welds the flange 22 to the portion of the blank 10 that contacts it. On the other hand, the anvil is on the opposite side of the ultrasonic horn and supports the flange 22 and the portion of the blank 10 that contacts it.

[0037] Either the ultrasonic horn or the anvil may be positioned on the outer surface of the container. If the ultrasonic horn is positioned on the outer surface of the container, the anvil will be positioned on the inner surface of the container. Conversely, if the anvil is positioned on the outer surface of the container, the ultrasonic horn will be positioned on the inner surface of the container. Therefore, of the ultrasonic horn and the anvil, the one positioned on the outer surface of the container is called the outer welding tool, and the one positioned on the inner surface of the container blank is called the inner welding tool. As mentioned above, the outer welding tool may be either an ultrasonic horn or an anvil, but in this embodiment, the outer welding tool 31 is an ultrasonic horn and the inner welding tool 41 is an anvil.

[0038] The surface of the outer welding tool 31 facing the container blank 10 is ring-shaped and surrounds the periphery of the pouring tube 21 of the stopper 20, but its surface is flat and has no irregularities. If there are irregularities on this surface, depressions corresponding to the irregularities may be formed in the container blank 10 when the outer welding tool 31 is pressed against the outer surface of the container blank 10.

[0039] Meanwhile, since the flange 22 of the plug 20 is ring-shaped as described above, the flange-side surface of the inner-side welding tool 41 is correspondingly ring-shaped. A protrusion 41a is provided on a portion of the ring-shaped surface. This protrusion 41a is narrower than the ring-shaped surface but is provided around the entire circumference. This protrusion 41a strongly presses against the flange 22 of the plug 20. In this way, the flange 22 and the portion of the blank 10 abutting it are strongly pressed between the outer-side welding tool 31 and the inner-side welding tool 41 while they are overlapped, and heat is generated by vibration due to ultrasonic irradiation, causing welding. The inner-side welding tool 41 has a protrusion 41a provided around the entire circumference, and this ring-shaped protrusion is pressed against the inner surface of the blank, allowing the plug to be liquid-tightly welded without seal loss.

[0040] In this embodiment, the protrusion 41a provided on the ring-shaped surface of the inner welding tool 41 is a single ring, but it can also be a double or triple ring. Of course, by using a double or triple ring, it is possible to more reliably prevent the seal from slipping out.

[0041] Next, the base 51 supports the dispensing tube 21 of the stopper 20 from the inside of the container. For this reason, it is arranged in the area surrounded by the ring-shaped surface of the inner-side welding tool 41. This base 51 must not be integral with the inner-side welding tool 41, but must be independent from the inner-side welding tool 41. In other words, when the outer-side welding tool 31 presses the container from the outside, and the inner-side welding tool 41 and base 51 press the container from the inside, the inner-side welding tool 41 and base 51 must be configured to withstand the pressure independently of each other in response to the pressure. If the inner-side welding tool 41 and base 51 were configured integrally, a pinhole would be formed during welding. In contrast, in this ultrasonic welding device A1, the inner surface welding tool 41 and the base 51 are independent of each other, so the spout tube of the stopper is properly supported during welding, preventing pinholes from occurring.

[0042] 1(b), it is desirable that the ring-shaped surface of the inner surface welding tool 41 is disposed closer to the plug 20 than the pouring tube side surface of the base 51. The height difference x is, for example, 0.2 mm.

[0043] However, because the base 51 that supports the dispensing tube 21 does not absorb ultrasound, the plug 20 may become partially hot and break into string-like pieces, producing foreign matter. To prevent the production of such foreign matter, the surface of the base 51 facing the dispensing tube 20 is provided with fine irregularities 51a. By providing the irregularities on the surface of the base facing the dispensing tube in this way, it is possible to prevent the production of such foreign matter. In this embodiment, the irregularities 51a are made up of recesses arranged in a matrix, but the shape, depth, and pitch thereof may be arbitrary.

[0044] The ultrasonic welding apparatus A1 according to the first embodiment has been described above. From the above description, it should be clear how to ultrasonically weld the stopper 20 to the container blank 10 using this apparatus A1. The container blank 10 and stopper 20 are positioned in a predetermined relationship and set into the ultrasonic welding apparatus A1. An outer welding tool 31 is placed on the outer surface of the container, and an inner welding tool 41 and a base 51 are placed on the inner surface. Then, by applying pressure from the inside and outside and irradiating with ultrasonic waves, the container blank 10 and the stopper 20 can be welded together. There are no depressions on the outer surface of the container, and of course, no missing seal or pinholes. Furthermore, because the surface of the base 51 facing the dispensing tube 20 has fine irregularities 51a, no foreign matter is generated during ultrasonic welding.

[0045] (Second embodiment) FIG. 2 relates to a second embodiment of the present invention, and FIG. 2(a) is a cross-sectional explanatory view of the main part during welding using an ultrasonic welding device according to the second embodiment, and FIG. 2(b) is an enlarged cross-sectional explanatory view showing the relationship between the ring-shaped surface of the inner welding tool and the surface of the base on the pouring tube side.

[0046] This ultrasonic welding device A2 is similar to the first embodiment in that the surface of the base 52 facing the dispensing tube 20 is flat and smooth. That is, the outer surface welding tool 32 of the ultrasonic welding device A2 is an ultrasonic horn, the same as the outer surface welding tool 31 of the first embodiment, and the inner surface welding tool 42 is an anvil, the same as the inner surface welding tool 41 of the first embodiment. Furthermore, the base 52 is similar to the base 51 of the first embodiment, except that its surface is smooth. Also similar to the first embodiment, the ring-shaped surface of the inner surface welding tool 42 is positioned closer to the stopper 20 than the surface of the base 52 facing the dispensing tube.

[0047] When this ultrasonic welding device A2 is used, no dents are formed on the outer surface of the container, and of course no missing seal or pinholes occur. However, because the surface of the base 52 facing the dispensing tube 20 is flat, foreign matter may be generated during ultrasonic welding.

[0048] (Third embodiment) Next, Figure 3 relates to a third embodiment of the present invention, and Figure 3(a) is a cross-sectional explanatory diagram of the main parts during welding using an ultrasonic welding device related to the third embodiment, Figure 3(b) is an enlarged cross-sectional explanatory diagram showing the relationship between the ring-shaped surface of the inner surface welding tool and the dispensing tube side surface of the base, and Figure 3(c) is an enlarged plan view explanatory diagram showing the positional relationship between the dispensing tube side surface of the base and the urging part.

[0049] In this ultrasonic welding device A3, the surface of the base 53 on the side of the dispensing tube 20 is flat and has no irregularities, and a biasing part 60 is disposed on the back surface of the base 53. 21 of the first embodiment. In other respects, the second embodiment is similar to the first embodiment. That is, the outer surface welding tool 33 of the ultrasonic welding device A2 is an ultrasonic horn, which is the same as the outer surface welding tool 31 of the first embodiment, and the inner surface welding tool 43 is an anvil, which is the same as the inner surface welding tool 41 of the first embodiment. The second embodiment is similar to the first embodiment except that the surface of the second embodiment is smooth. The ring-shaped surface of the inner surface welding tool 43 is also positioned closer to the stopper 20 than the surface of the base 53 on the side of the dispensing tube, which is the same as the first embodiment.

[0050] Examples of the biasing member 60 include a spring and an elastic body such as rubber. The number and arrangement of the biasing members 60 may be arbitrary as long as the surface of the base 53 is uniformly biased toward the dispensing tube 21. In this embodiment, however, as shown in Fig. 3(c), springs are arranged at eight equally divided positions on the back surface of the base 53.

[0051] When this ultrasonic welding device A3 is used, no dents are formed on the outer surface of the container, and of course no missing seal or pinholes occur. Moreover, even though the surface of the base 53 facing the dispensing tube 20 is flat, the biasing component 60 is disposed on the back surface of the base 53 to bias it toward the dispensing tube 21 of the stopper 20, so no foreign matter is produced during ultrasonic welding. [Example]

[0052] The present invention will be explained below by comparing examples and comparative examples.

[0053] The containers used in these examples and comparative examples are liquid paper containers described in JP 2019-026274 A.

[0054] This liquid-carton container is constructed by overlapping an upper sheet and a lower sheet and sealing them together at the periphery, and can be in either a flat or box-shaped state. Figure 6 shows a blank for the upper sheet, and Figure 7 shows a blank for the lower sheet. Figure 8 is a perspective view showing the upper and lower sheets overlapped, and Figure 9 is a perspective view of the liquid-carton container in a box-shaped state.

[0055] As can be seen from Figure 6, a through hole is provided on the top surface of the blank of the upper sheet, and a plug 20 is attached to this through hole. In the examples and comparative examples described below, the plug 20 is attached to this blank of the upper sheet.

[0056] Example 1 Example 1 is an example in which the ultrasonic welding device A1 according to the first embodiment was used. The height difference x between the ring-shaped surface of the inner welding tool 41 and the surface of the base 51 on the pouring tube side was set to 0.2 mm.

[0057] Example 2 Example 2 is an example in which the ultrasonic welding device A2 according to the second embodiment was used. The height difference x between the ring-shaped surface of the inner welding tool 42 and the surface of the base 52 on the pouring tube side was set to 0.2 mm.

[0058] Example 3 Example 3 is an example in which ultrasonic welding device A3 according to the third embodiment was used. The height difference x between the ring-shaped surface of inner-side welding tool 43 and the surface of base 53 on the pouring tube side was set to 0.2 mm.

[0059] (Comparative Example 1) This example uses a conventional ultrasonic welding device.

[0060] 10, the ultrasonic welding device B uses an ultrasonic horn with a ring-shaped protrusion 36a on the container blank side as the outer welding tool 36. On the other hand, an anvil with a flat, even surface on the flange 22 side is used as the inner welding tool 46.

[0061] 10, the inner welding tool (anvil) 46 is cylindrical, not ring-shaped. This shape is an integral combination of the ring-shaped inner welding tool and a base surrounded by the ring-shaped inner welding tool.

[0062] (Comparative Example 2) This example uses an ultrasonic welding device without a base.

[0063] FIG. 4 is an explanatory cross-sectional view of a main part showing welding using this ultrasonic welding device C.

[0064] That is, this ultrasonic welding device C uses an anvil with a flat surface facing the container blank as the outer welding tool 34. Also, an ultrasonic horn with a ring-shaped surface facing the flange and a protrusion 44a on part of the ring-shaped surface is used as the inner welding tool 44. No pedestal is disposed in the area surrounded by this ring-shaped inner welding tool 44.

[0065] (Comparative Example 3) This example uses ultrasonic welding device D, which is provided with a base integrated with the inner welding tool. The ring-shaped surface of the inner welding tool is positioned closer to the stopper than the surface of the base on the pouring tube side.

[0066] FIG. 5 is a cross-sectional explanatory view of the essential parts showing welding using this ultrasonic welding device D.

[0067] That is, this ultrasonic welding device D uses, as the outer welding tool 35, an anvil with a flat surface facing the container blank. Also, as the inner welding tool 45, an ultrasonic horn with a ring-shaped surface facing the flange and a protrusion 45a provided on a portion of the ring-shaped surface is used. As can be seen from the figure, this protrusion 45a is wide, and therefore faces not only the flange 22 of the stopper 20 but also the pouring tube 21. That is, this protrusion 45a serves both as the inner welding tool and as the base in the present invention. In other words, in this ultrasonic welding device D, the base is not separate from the inner welding tool, but the two are integrated. Of course, the height difference x between the ring-shaped surface of the inner welding tool and the surface of the base facing the pouring tube is 0 mm.

[0068] (Results and Discussion) The plugs were ultrasonically welded without missing seals using the ultrasonic welding devices of Examples 1 to 3 and Comparative Examples 1 to 3. The results were evaluated from four perspectives.

[0069] First, the blank 10 was evaluated as to whether or not a dent was formed on the outer surface of the container. If no dent was formed, it was evaluated as "good", and if a dent was formed, it was evaluated as "poor".

[0070] Next, whether pinholes occurred due to welding was evaluated. Plugs were welded to a large number of blanks, and if pinholes occurred in 1% or more of the blanks, it was evaluated as "X", and if not, it was evaluated as "O".

[0071] Next, the variation in the length of the stoppers protruding from the outer surface of the container was evaluated by welding stoppers to a large number of blanks and subtracting the minimum from the maximum length of the stoppers protruding from the outer surface of the container.

[0072] Finally, we evaluated whether or not foreign matter was generated during welding. In this evaluation, we evaluated whether or not foreign matter with a length of 8 mm or more was generated.

[0073] The results are shown in Table 1. In the table, "single ring" means that a single ring-shaped protrusion is provided on the blank side surface of the outer welding tool or the flange side surface of the inner welding tool.

[0074] [Table 1]

[0075] As can be seen from Table 1, when a single ring-shaped protrusion is provided on the container blank side surface of the outer welding tool (Comparative Example 1), a depression corresponding to the protrusion is formed on the container outer surface of the blank to which the stopper is welded. On the other hand, in other examples (Examples 1 to 3, Comparative Examples 2 and 3) in which the container blank side surface of the outer welding tool is flat, no such depression is formed.

[0076] Next, in the case where there is no base supporting the spout of the stopper (Comparative Example 2), there is a large variation in the length of the stopper protruding from the outer surface of the container. In such cases, the dispensing of the contents also varies, which can impair the usability of the container. In addition, the cap that seals the stopper may tilt, making it impossible to seal.

[0077] Even if there is a base that supports the spout of the spout, if this base is integrally formed with the inner welding tool and is not independent (Comparative Example 3), pinholes are likely to occur during ultrasonic welding.

[0078] In contrast to this, when a seat independent from the inner surface welding tool is provided (Examples 1 to 3), the above-mentioned variations are small and pinholes are less likely to occur.

[0079] Even in this case, in Example 2, where the surface of the base is not uneven, the stopper may become partially hot during ultrasonic welding, causing it to break into string-like pieces and produce foreign matter. In contrast, if the surface of the base facing the pouring tube is uneven as in Example 1, such foreign matter will not be produced. Even if there are no unevenness, if a biasing component is provided that biases the base toward the pouring tube of the stopper as in Example 3, foreign matter will also not be produced. [Explanation of symbols]

[0080] 10: Container blank 20: Spout 21: Dispensing tube 22: Flange 31,32,33,34,35,36:Outer side welding tool 36a: Ring-shaped protrusion of outer welding tool 41,42,43,44,45,46:Inner side welding tool 41a, 42a, 43a, 44a, 45a: Ring-shaped protrusions of inner surface welding tools 51, 52, 53: Base 51a: Unevenness of the base 60: Actuating parts

Claims

1. An apparatus for ultrasonically welding a stopper to a container blank, comprising: a through hole is provided in the container blank, and the stopper is configured to have a pouring tube for pouring the contents and a flange provided around the pouring tube, and the pouring tube of the stopper is inserted into the through hole, and with the flange abutting against the inner surface of the container blank around the through hole, the flange and the blank at the abutting portion are clamped between an ultrasonic horn and an anvil, and ultrasonic waves are irradiated from the ultrasonic horn to weld the flange of the stopper to the inner surface of the container blank, When the ultrasonic horn and the anvil, which are arranged on the outer surface side of the container blank, are referred to as an outer surface welding tool, and the ultrasonic horn and the anvil, which are arranged on the inner surface side of the container blank, are referred to as an inner surface welding tool, the entire portion of the outer welding tool's surface on the container blank side that overlaps with the flange is flat; On the other hand, the surface of the inner welding tool on the flange side is ring-shaped, and a ring-shaped protrusion is provided on the ring-shaped surface around the entire circumference, Furthermore, a base for supporting the pouring tube of the spout is provided in an area surrounded by the ring-shaped surface of the inner surface welding tool, Moreover, the ultrasonic welding device for a plug is characterized in that the base is independent from the inner surface welding tool.

2. 2. The ultrasonic welding device according to claim 1, wherein the surface of the base facing the pouring tube is provided with irregularities.

3. 3. The ultrasonic welding device according to claim 1, wherein the ring-shaped surface of the inner welding tool is disposed closer to the stopper than the surface of the base on the side of the pouring tube.

4. 4. The ultrasonic welding device according to claim 3, wherein the ring-shaped surface of the inner welding tool is disposed 0.2 mm closer to the stopper than the surface of the base on the side of the pouring tube.

5. 5. The ultrasonic welding device according to claim 1, further comprising a biasing member for biasing the base toward the dispensing tube of the stopper.

6. A method for welding a stopper, comprising ultrasonically welding the stopper to a container blank using the ultrasonic welding device according to any one of claims 1 to 5.

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