JPH0572857B2 - - Google Patents

Abstract

PURPOSE:To secure the transmission of super-sonic oscillation to a welding sheet and to make the welding film, by making a plane where the horn and the anvil of the super-sonic oscillator contact the welding sheet into a specific shape. CONSTITUTION:The side faces of convex parts 5, 5 provided at planes 3, 3 where the horn 1 and the anvil 2 of a super-sonic oscillator contact a welding sheet are inclined at theta deg. and become inclined slopes 6. By making the convex parts 5, 5 into trapezoid forms by providing such inclined slopes 6, when multi- layered sheets are welded each other it becomes easier for the convex parts 5 to bite into the above-mentioned sheet. It is possible for the convex parts 5 to bite the multi-layered sheet to the inside layer which becomes a welding surface side in each layer, and super-sonic oscillation can be certainly transmitted to be welding surface.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an ultrasonic sealing device, and more particularly to an uneven pattern to be carved on the contact surface of a horn and anvil that clamps a sheet-like object, which is an object to be sealed, with the sheet-like object. . [Prior art and its problems] Ultrasonic sealing devices that weld a pair of sheet materials together using ultrasonic vibrations include so-called longitudinal vibration type devices that apply ultrasonic vibrations in a direction perpendicular to the welding surface; The so-called transverse vibration type, which applies ultrasonic vibration in a direction parallel to the plane, was developed by the applicant of the present invention in Japanese Patent Application No. 56-123692 (Japanese Unexamined Patent Publication No. 58-33424).
Patent Application No. 1987-87765 (Patent Application No. 1987-205723)
There are three types of diagonal vibration type proposed in No. 1, which applies ultrasonic vibration diagonally to the welding surface. Looking at the characteristics of each of these three types, the longitudinal vibration type applies vibration in a direction perpendicular to the welding surface, so a so-called lateral slip phenomenon occurs between the horn and anvil and the sheet material to be welded. Therefore, there is essentially no need to carve a concavo-convex pattern on the contact surface of the horn or anvil that comes into contact with the sheet-like object. However, since the vibration is applied in a direction perpendicular to the welding surface, even if foreign matter adheres to the welding surface, it cannot be blown away laterally by vibration. It is not suitable for welding the bottom part. Next, the transverse vibration type has the ability to vibrate and blow away foreign matter attached to the welding surface in the horizontal direction, but since it applies vibration in a direction parallel to the welding surface, the horn and anvil A side-slipping phenomenon occurs between the horn and the sheet material held between the horns, and vibrations are not efficiently transmitted to the welding surface, causing the horn to generate heat, and frictional heat due to vibrations is not generated sufficiently. There are problems such as poor welding, unpleasant high-pitched sounds due to side slipping, and hangnails or scrapes on the surface of the sheet material that is in contact with the horn or anvil. Therefore, a concavo-convex pattern as shown in FIG. 12 is engraved on the contact surface of the horn and anvil with the sheet-like material, but very good results have not been obtained with the concave-convex pattern shown in FIG. Finally, the diagonal vibration type has the advantages of both the vertical vibration type and the horizontal vibration type because the vibrations are dispersed in the vertical and horizontal directions, and has the ability to blow away foreign objects attached to the welding surface in the horizontal direction. At the same time, it also has the effect of suppressing the horizontal slip phenomenon to some extent, and can perform welding more efficiently than the longitudinal vibration type or the horizontal vibration type. Therefore, good results have been shown in the welding of multilayer sheets, which is not so good with the transverse vibration type. However, the fact remains that a side-slip phenomenon occurs, and this side-slip phenomenon cannot be eliminated even by carving a concave-convex pattern on the contact surface as shown in Fig. 12. Efficient welding is desired. In this way, in transverse vibration type and diagonal vibration type ultrasonic sealing devices, whether or not ultrasonic vibrations can be transmitted efficiently depends on the contact surface of the horn and anvil that clamps the sheet material. It depends on what kind of uneven pattern you want to create, but in that case, be careful to leave as much of the bonding surface parallel to the welding surface as possible on the horn or anvil in order to efficiently generate frictional heat on the welding surface. This is to ensure that the uneven pattern formed on the horn and anvil bites into the horn and anvil to eliminate side slipping. The case where the contact surface parallel to the welding surface is maximum is when no uneven pattern is provided, but in this case, the degree of side slip is also maximum as described above. On the other hand, the case where the penetration of the uneven pattern is maximized is when the tip of the convex part is made sharp, but in this case, there is no contact surface parallel to the welding surface, so ultrasonic vibrations are transmitted to the welding surface. It is difficult to generate frictional heat. Considering the concavo-convex pattern shown in FIG. 12 from this point of view, the convex portion 5 having a rectangular planar shape is formed by the inclined intersecting grooves 4, and the side surfaces of the convex portion 5 are vertically connected. Since the surface 21 is formed as a surface 21, the convex portion 5 is difficult to bite into the sheet-like object, and side slipping cannot be reliably suppressed. Also, as another conventional example, Japanese Patent Application Laid-Open No. 60-201928

[Fig. 13 a, b, c], a horn for ultrasonic sealing is formed by carving a plurality of uneven lines 22 with corners cut at a constant depth and protrusion height along the longitudinal direction of the contact surface. 1 is stored, and specifically, it is described that the uneven line 22 is a continuous uneven surface having a sinusoidal shape with no corners in the transverse cross section of the contact surface 3. However, it is clear from Figure 13a that the ultrasonic sealing device described in this publication is of the longitudinal vibration type (the vibration direction of the ultrasonic wave is in the axial direction of the horn, and the tip of the horn in the axial direction (It is understood that vibration is applied in a direction perpendicular to the welding surface of the sheet because of the contact surface provided.) Therefore, an uneven pattern to prevent side slipping is essentially unnecessary. Nevertheless, the purpose of providing the uneven stripes 22 is to hold the resin melted by ultrasonic vibration in a flowing position at the sealing portion, thereby increasing the welding ability. Even if this structure is used in a transverse vibration type or diagonal vibration type device, since the cross section of the concavo-convex stripes 22 is sinusoidal, there is no contact surface 3 parallel to the welding surface, and the frictional heat is sufficiently absorbed. In addition, the uneven streaks 22 that have dug in have little effect in suppressing lateral slip. Against this background, the inventors of the present invention etched various uneven patterns on the contact surfaces of horns and anvils and repeated experiments. In order to ensure that the convex part bites into the sheet-like object, the contact surface parallel to the welding surface is at its maximum, i.e., when no convex part is provided.

[Fig. 11a] is the state where the convex part has maximum bite, that is, the tip of the convex part is sharpened.

[11th
Intermediate state with Figure b

It has been found that the method shown in FIG. 11c is the most effective. The present invention was made against this background, and is directed to improving the uneven pattern to be carved on the contact surface of a horn and anvil that clamps a sheet-like object to the sheet-like object in an ultrasonic sealing device. Therefore, it is a technical problem to efficiently transmit ultrasonic vibrations to sheet-like objects so that welding can be performed reliably and firmly. [Means for Solving the Problems] In order to solve the above-mentioned technical problems, the present invention sandwiches a pair of sheet-like objects between a horn 1 and an anvil 2, and uses frictional heat generated by ultrasonic vibration to heat the pair of sheets. The following technical measures were taken in an ultrasonic sealing device for welding sheet materials together. In addition,
The ultrasonic sealing device in this case is limited to a transverse vibration type or an oblique vibration type, as a logical premise for the purpose of the present invention. The gist of the present invention is that grooves 4 are formed in each contact surface 3 of the horn 1 and the anvil 2 that contact the pair of sheet-like materials.
The convex portion 5 whose upper surface is flat by forming
A plurality of ridges are formed, and the side surfaces of the ridges 5 are sloped surfaces 6 so that the cross section of the ridges 5 is trapezoidal. Here, the inclination angle θ of the inclined surface 6 needs to be changed somewhat depending on the material of the sheet to be welded, but it is generally 5 to 45 degrees, preferably 10 to 30 degrees. Further, grooves 4 for forming the plurality of convex portions 5 are provided.
It is conceivable that there are cases in which a straight pattern is carved so as to intersect with each other, and there are cases in which it is carved so as to form a curved pattern that is not straight. In the former case, as shown in Figures 7 and 8,
It is formed by rectangular or triangular convex portions 5 or a continuous pattern; in the latter case, a zigzag pattern or wave pattern is formed when viewed from the plane, or as shown in Fig. 9, octagonal convex portions 5 are formed alternately. , a pattern in which hexagonal (honeycomb) convex portions 5 are continuously repeated (Fig. 1), and even circular convex portions 5
An example of this is the case where a pattern (FIG. 10) is formed in which the following steps are repeated. The size of the pattern formed by these grooves 4 and convex portions 5 is determined by taking into consideration the factors of generating more frictional heat, shortening the sealing time, and minimizing the pressing force by the horn 1 and the anvil 2. The distance l (pattern pitch) from one end of one convex part 5 to one end of another convex part 5 adjacent to it is 0.5 to 2.0.
mm, preferably 0.8 to 1.6 mm.
In addition, the shape and size of the convex portion 5 on the horn 1 side,
The shape and size of the convex portion 5 on the anvil 2 side may be made different. Furthermore, in order to obtain sufficient frictional heat, it is necessary to leave a certain amount of plane parallel to the welding surface.
For example, in the case of the honeycomb convex portion 5, the ratio of the ratio occupied by the grooves 4 to the proportion occupied by the flat surface of the upper surface of the honeycomb convex portion 5 is 30:70 to 64:36, preferably around 40:60. In addition, if the groove 4 for forming the convex part 5 is too deep, when welding thermoplastic resin sheets together, the convex part 5 will dig into the sheet too deeply, causing the thickness of the welded part to become thin and tearing. Moreover, if the volume of the groove 4 becomes too large and a large amount of molten resin enters therein, the appearance of the sealed portion will deteriorate if it solidifies. On the other hand, if the groove 4 is too shallow, the amount of bite of the convex portion 5 will be small, making it insufficient to suppress the side-slip phenomenon, and the efficiency of generating frictional heat at the welding surface will deteriorate. Therefore, the depth of the groove 4 is 35 to 65%, preferably 40 to 65%, of the thickness of one of the pair of sheets to be welded.
6% is preferred. By the way, the grooves 4 on the horn 1 side and the grooves 4 on the anvil 2 side do not need to have the same depth, and one may be deeper than the other. By the way, the pair of sheet-like objects to be welded by the ultrasonic sealing device of the present invention is a single-layer sheet of thermoplastic resin, a multi-layer sheet of thermoplastic resin, or a thermoplastic resin layer and a material other than synthetic resin, such as paper or aluminum. It is a multilayer sheet formed with a sheet layer of 1, and can be used, for example, to weld the bottom of a tube container containing cosmetics, toothpaste, etc. Regarding the multilayer sheet of thermoplastic resin, when using a multilayer sheet in a tube container, a multilayer tube with an inner layer of high density polyethylene (HDPE) and an outer layer of low density polyethylene (LDPE), or high density polyethylene A multilayer tube in which a gas barrier resin layer such as EVAL or nylon is provided between a layer and a low-density polyethylene layer, and a multilayer sheet with sheet layers of different materials is a multilayer tube with an aluminum laminate layer in the middle layer. It will be done. [Function] According to the present invention, since the side surface of the convex portion 5 provided on the contact surface 3 of the horn 1 and the anvil 2 is formed into an inclined surface 6, it is easy to bite into a sheet-like object. In particular, when welding multilayer sheets together, the protrusions 5 tend to bite into each other, so by appropriately selecting the height of the protrusions 5, that is, the depth of the grooves 4, as shown in FIG. 4b, Among the layers of the multilayer sheet, the convex portions 5 can penetrate into the inner layer on the welding surface side, and ultrasonic vibrations can be reliably transmitted to the welding surface to efficiently generate frictional heat. be able to. In this respect, if the convex part 5 bites only into the outer layer, the ultrasonic vibrations will not be transmitted directly to the inner layer, but will be transmitted through the outer layer, and will be attenuated when transmitted from the outer layer to the inner layer. Therefore, sufficient frictional heat is not generated. In particular, when welding the bottom of a multilayer tube that has polyethylene layers as the inner and outer layers and an EVAL layer as the middle layer, the polyethylene layer and the EVAL layer are not bonded together due to the nature of the resin, so the convex part extends to the inner polyethylene layer. Welding was difficult with conventional means in which the protrusions 5 do not cut into the inner layer, but according to the present invention, the protrusions 5 cut into the inner layer, so welding can be performed satisfactorily. Further, by forming the inclined surface 6, the cross section of the groove 4 itself also becomes trapezoidal, and the sheet-like material that has cut into the groove 4 is likely to be peeled off from the pattern surface after welding. If the grooves 4 for forming the convex portions 5 are not straight but have a curved pattern, the resin melted by the ultrasonic vibrations is evenly distributed over the welding surface along the grooves 4. Therefore, there is no unevenness in the welding of the pair of sheet-like materials, and the welding can be performed reliably and firmly. This effect is most remarkable when the planar shape of the convex portion 5 formed by the curved pattern of grooves 4 is a honeycomb. In this regard, if the groove 4 is straight, the molten resin will flow in only one direction, and there will be parts with too little molten resin and parts with too much molten resin on the welding surface, resulting in uneven welding, and in the worst case, parts will not be welded. There is a risk. Furthermore, in order to obtain sufficient frictional heat, it is necessary to leave a certain amount of plane parallel to the welding surface.
In the case of the present invention, since the upper surface of the convex portion 5 is left as a flat surface, there is no problem in this point. In addition, in the case of an oblique vibration type ultrasonic sealing device, ultrasonic vibrations are applied from an oblique direction, and even when welding the bottom of a tube container, for example, even if there is a filler attached to the welding surface, the ultrasonic vibration is applied to the outside of the welding surface. As mentioned above, it is possible to scatter the filling, but if the convex portion 5 whose side surface is an inclined surface 6 is provided on the contact surface 3 of the horn 1 or the anvil 2 as in the present invention, side slipping is reduced. Therefore, the effect of scattering the filler to the outside of the welding surface is more effectively performed. Therefore, welding can be performed even with cosmetics attached to the welding surface, and furthermore, the tube container is filled with cosmetics,
It can be sealed and welded while the cosmetic liquid remains attached to the welding surface. [Examples and Comparative Examples] First, the oblique vibration type ultrasonic sealing device and the transverse vibration type ultrasonic sealing device used in the Examples and Comparative Examples will be described. As shown in FIG. 3, the oblique vibration type ultrasonic sealing device has a support arm 12 rotatably connected to the tip of a support rod 11, and an ultrasonic oscillator 1 attached to the support arm 12.
3. The amplifier 14 and the horn 1 are installed on the same axis, and ultrasonic vibrations are oscillated in the direction of this axis. And the horn 1
has a pair of contact surfaces 3 on both sides of the tip, and each contact surface 3 has an angle ψ with respect to the axis of the horn 1.
It is tilted at an angle of 20 degrees, and the contact surface 3
The honeycomb-shaped convex portions 5 shown in FIG. 1 are formed in a repeating pattern. And this convex part 5
The angle θ of the side surface of is also set to an angle of 20 degrees.
In addition, the pitch l of the pattern is 1.1 mm, the ratio of the groove 4 to the plane on the convex part is 41:51, and the depth of the groove 4 is 0.2 mm.
It is. When one contact surface 3 at the tip of the horn 1 is fixed upright, the axis connecting the ultrasonic oscillator 13, amplifier 14, and horn 1 is supported at an angle of 20 degrees with respect to this upright contact surface 3. The arm 12 is now fixed, and thus the position of the horn 1 is fixed. Then, an anvil 1 is installed opposite the contact surface 3 of the tip of the upright horn 1, and this anvil 2
A contact surface 3 is formed on the opposite surface of the horn 1 side, and this contact surface 3 is also formed with a honeycomb-shaped convex portion 5 shown in FIG. The specifications of this convex portion 5 are the same as those of the convex portion 5 on the horn 1 side. And this anvil 2
is provided so that it can move forward and backward toward the horn 1 side by a hydraulic cylinder (not shown), and the contact surface 3 of the tip of the horn 1 and the contact surface 3 of the anvil 1 are set to be 10 mm apart in the forward and backward positions. As shown in FIG. 4a, when the anvil 2 is retracted, the bottom of the tube container 17, which has a circular cross section and is conveyed while being held by the holder 16 on the belt conveyor 15, is flattened and the horn 1 The guide 18 that guides between the horn 1 and the anvil 2
The guide 18 is provided adjacent to the anvil 2 and has a pair of opposing tapered surfaces 19, 19 to flatten the tube container 17. The bottom of the tube container 17 that has entered between the horn 1 and the anvil 2 is pressed between the contact surface 3 of the tip of the horn 1 and the contact surface 3 of the anvil 2 as the anvil 2 advances, and is welded by ultrasonic vibration. .
Since this ultrasonic vibration is applied at an angle of 20 degrees to the welding surface at the bottom of the tube container 17, it is dispersed in a direction perpendicular to the welding surface and in a direction parallel to the welding surface. Next, in the transverse vibration type ultrasonic sealing device, as shown in FIGS. 5 and 6, the axis connecting the ultrasonic oscillator 13, amplifier 14, and horn 1 is fixed upright, and A pair of parallel contact surfaces 3 are provided on both sides of the tip of the horn 1, and other points are the same as the oblique vibration type ultrasonic sealing device. In this case, ultrasonic vibrations vibrating in the axial direction of the horn 1 are applied via the contact surface 3 to the welding surface of the tube container 17 in a direction parallel to it. Hereinafter, tube containers 17 made of various materials will be
Since we sealed the bottom of the and measured the seal strength,
The results are shown in Table 1. The uneven patterns formed on the contact surfaces 3 of the horn 1 and the anvil 2 are a honeycomb pattern shown in FIG. 1 and a conventional square pattern shown in FIG. 12.

【table】

[Table] As is clear from Table 1, the one in which the honeycomb-shaped protrusion 5 is provided on the contact surface 3 seals better than the conventional one. Very good results can be obtained when combined. Since the side surfaces of the convex portions 5 were sloping surfaces 6, they could be easily penetrated, the unpleasant friction noise generated during sealing was small, and the sheet-like material could be easily removed from the pattern surface after sealing. Since the combination of the oblique vibration type ultrasonic sealing device and the honeycomb-shaped convex portion 5 is good as described above, experimental data for this combination is shown in Table 2.

【table】

〔Effect of the invention〕

According to the present invention, since the side surface of the convex portion provided on the contact surface between the horn and the anvil is made into an inclined surface, it easily bites into the sheet-like object, thereby suppressing the side-slipping phenomenon as much as possible, and preventing ultrasonic vibration from welding. It can be transmitted reliably to the surface and generates frictional heat efficiently, making welding reliable and strong. Therefore, it is now possible to successfully weld multilayer sheets, which was conventionally considered impossible by ultrasonic welding, and it is particularly effective in welding multilayer sheets having EVAL in the middle layer. In addition, since the ultrasonic vibrations are transmitted reliably, the horn generates less heat, and the horn does not require much cooling, allowing continuous and speedy welding. Furthermore, since the sideslip phenomenon has decreased,
Unpleasant sealing noise generated during welding can be reduced, and the working environment can be improved. In addition, since the side-slip phenomenon is eliminated, there are no hangnails or scrapes on the surface of the sheet material held between the horn and the anvil, and a beautiful finish can be achieved. In addition, since the cross section of the convex part is trapezoidal, the sticking phenomenon of sheet-like objects is greatly reduced, and sheet-like objects that have dug into the grooves can be easily peeled off from the pattern surface after welding, and cuts do not occur in the sheet-like objects. . From the above, whereas conventionally it was necessary to prepare sealing devices suitable for various materials such as heat seals, high frequency seals, and ultrasonic seals, by using the horn and anvil of the present invention, A single ultrasonic sealing device can seal various materials, weld firmly and reliably, and the appearance of the welded portion can be made extremely beautiful. By the way, in order to ensure reliable welding, the conventional ultrasonic sealing device for welding the bottom of a tube container is equipped with a holding device 20 called a Jaw, as shown in FIGS. 14 and 15. Previously, the bottom of the tube container was clamped near the welded part at the bottom of the tube container, and then the bottom of the tube container was clamped and welded between a horn and an anvil.However, according to the present invention, welding is reliable and strong, so this type of welding is possible. There is no need for auxiliary equipment, and the device can therefore be simplified.

[Brief explanation of the drawing]

Figures 1a and b are a plan view and a cross-sectional view showing an example of the uneven pattern according to the present invention, Figure 2 is a front view of the horn and anvil portion of an oblique vibration type ultrasonic sealing device, and Figure 3 is an oblique vibration type ultrasonic sealing device. A front view of the ultrasonic sealing device, Fig. 4a is a process diagram showing the process of sealing the bottom of a tube container, Fig. 4b is a sectional view showing the state of the convex part biting in, and Fig. 5 is a transverse vibration type ultrasonic A front view of the sealing device, FIG. 6 is a front view of its horn and anvil portion, FIGS. 7 to 10 are plan views showing other examples of uneven patterns, and FIG. 11 is a sectional view showing the progress leading to the invention. , FIGS. 12a and 12b are plan views and sectional views showing a conventional uneven pattern, FIGS. 13a, b, and c are views showing another conventional example of a horn and its contact surface, and FIG. 14 is a conventional example. FIG. 15 is a front view showing the oblique vibration type ultrasonic sealing device, and FIG. 15 is a sectional view showing the jaw portion thereof. 1... Horn, 2... Anvil, 3... Contact surface, 4... Groove, 5... Convex portion, 6... Inclined surface.

Claims (1)

[Scope of Claims] 1. In a horn and anvil of an ultrasonic sealing device that clamps a pair of sheet-like objects and welds the pair of sheet-like objects together using frictional heat generated by ultrasonic vibration, the pair of sheet-like objects By forming grooves on each contact surface that comes into contact with the pair of sheet-like objects when holding an object, a plurality of convex portions with flat upper surfaces are formed, and the cross section of these convex portions becomes trapezoidal. A horn and an anvil for an ultrasonic sealing device, characterized in that the side surface of the convex portion is an inclined surface. 2. The horn and anvil of an ultrasonic sealing device according to claim 1, wherein the grooves for forming the plurality of convex portions form a bent pattern. 3. The horn and anvil of an ultrasonic sealing device according to claim 1, wherein the vibration direction of the ultrasonic waves is oblique to the welding surfaces of the pair of sheet materials. 4. The ultrasonic sealing device horn and anvil according to claim 1, wherein the vibration direction of the ultrasonic waves is parallel to the welding surfaces of the pair of sheet materials. 5. The horn and anvil of an ultrasonic sealing device according to claim 1, wherein the pair of sheet-like materials are single-layer sheets of thermoplastic resin. 6. The horn and anvil of an ultrasonic sealing device according to claim 1, wherein the pair of sheet-like materials are multilayer sheets of thermoplastic resin. 7. The ultrasonic sealing device horn and anvil according to claim 2, wherein the planar shape of each convex portion formed by the groove is a honeycomb shape. 8. The ultrasonic sealing device horn and anvil according to claim 2, wherein each convex portion formed by the groove has an octagonal planar shape. 9. The ultrasonic sealing device horn and anvil according to claim 2, wherein each convex portion formed by the groove has a circular planar shape. 10. The horn and anvil of an ultrasonic sealing device according to claim 6, wherein the multilayer sheet includes a sheet layer made of a thermoplastic resin and a different material.