WO2013027390A1

WO2013027390A1 - Ultrasonic sealing apparatus and ultrasonic sealing method

Info

Publication number: WO2013027390A1
Application number: PCT/JP2012/005231
Authority: WO
Inventors: Hiroki Yamamoto; Takumi Nakano; Kazuo Ukegawa
Original assignee: Unicharm Corporation
Priority date: 2011-08-24
Filing date: 2012-08-21
Publication date: 2013-02-28
Also published as: CN103747767A; JP5990568B2; IN2014CN01519A; JP2014524265A; TW201332749A; TWI574824B; CN103747767B

Abstract

Provided is an ultrasonic sealing apparatus that forms a plurality of welded sections at intervals along a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article. The apparatus includes an ultrasonic horn that emits the ultrasonic vibration; an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web; and a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track. The forward path has an equal speed region in which the ultrasonic horn and the anvil oppose each other in the thickness direction and move at a speed value which is the same as a transport speed value of the continuous web. The ultrasonic horn and the anvil perform a nipping and a releasing of the nipping of the continuous web while moving in the equal speed region. The ultrasonic horn emits the ultrasonic vibration during the nipping of the continuous web.

Description

ULTRASONIC SEALING APPARATUS AND ULTRASONIC SEALING METHOD

The present invention relates to an ultrasonic sealing apparatus and an ultrasonic sealing method that weld a continuous web relating to an absorbent article, such as a disposable diaper.

In a production line of an absorbent article such as a disposable diaper (hereinafter referred to as a diaper), it is commonly known to join a plurality of strips of continuous web by forming welded sections at intervals in a transport direction thereof while continuously transporting the plurality of strips of continuous web of a nonwoven fabric or the like in a layered state. PTL 1 discloses, as an apparatus to perform this, an ultrasonic sealing apparatus 120 as shown in a schematic side view in Fig. 1, including steps (A) to (F).

As shown in Fig. 1 in (A), the ultrasonic sealing apparatus 120 includes an ultrasonic horn 130 provided above a linear transport track Tr1a of a continuous web 1a, and an anvil 160 that is provided below the linear transport track Tr1a and cooperates with the ultrasonic horn 130 to pinch the continuous web 1a during the welding process. The horn 130, supported by a parallelogram linkage mechanism 135, is configured to make a circular motion in a vertical plane in accordance with the rotation of a short side linkage section 135S of the parallelogram linkage mechanism 135 while maintaining a major axis direction of the horn 130 arranged along a long side linkage section 135L of the parallelogram linkage mechanism 135 in the vertical direction. Thus, a nipping surface 130a at a lower end of the horn 130 is maintained in an always downwardly oriented state during the circular motion. Also, the anvil 160 is supported by a similar parallelogram linkage mechanism 165, and, in other words, configured to make a circular motion in a vertical plane in accordance with the rotation of a short side linkage section 165S of the parallelogram linkage mechanism 165, while maintaining a major axis direction of the anvil 160 arranged along a long side linkage section 165L of the parallelogram linkage mechanism 165 in the vertical direction. Thus, a nipping surface 160a at an upper end of the anvil 160 is maintained in an always downwardly oriented state during the circular motion (see Fig. 1, (A) to (F)).

Fig. 2 shows a track Tr130a of the nipping surface 130a on the horn 130 side and a track Tr160a of the nipping surface 160a on the anvil 160 side during such a circular motion, and basically, each of the

nipping surfaces

130a, 160a is making a substantially circular motion. It is to be noted that the circular motion of the nipping surface 130a on the horn 130 side and the circular motion of the nipping surface 160a of the anvil 160 side is in a mutually opposite direction, and on the transport track Tr1a of the continuous web 1a, the tracks Tr130a and Tr160a of the circular motions intersect with each other. Further, the nipping surface 160a on the anvil 160 side is attached to the long side linkage section 165L of the above-mentioned parallelogram linkage mechanism 160 via an appropriate elastic member, which is not shown, and thus the nipping surface 160a is supported in the vertical direction in an elastically displaceable manner.

Therefore, at an intersecting track section TrC where the tracks Tr130a and Tr160a of the horn 130 and the anvil 60 intersect, when the nipping surface 130a on the horn 130 side and the nipping surface 160a on the anvil 160 side oppose each other across the continuous web 1a (Fig. 1E), the nipping surface 160a on the anvil 160 side is pressed downwards by the horn 130 with the

nipping surfaces

130a and 160a nipping the continuous web 1a from above and from below, and thus the continuous web 1a is smoothly nipped with the nipping surface 130a on the horn 130 side and the nipping surface 160a on the anvil side 160. During the nipping, ultrasonic vibration is emitted from the nipping surface 130 on the horn 130 side towards the continuous web 1a, and thus a portion of the continuous web 1a that is being nipped melts and a welded section 14 is formed.

JP-A-07-204223

It has been described above that, as shown in Fig. 2, when the

nipping surfaces

130a and 160a pass the above-mentioned intersecting track section TrC, the nipping surface 130a on the horn 130 side pushes down the nipping surface 160a on the anvil 160 side, and at this time an angular velocity of the circular motion of the nipping surface 130a on the horn 130 side and an angular velocity of the circular motion on the anvil 60 side are the same value. Therefore, a peripheral speed of the nipping surface 130a on the anvil 130 side will be slower than a peripheral speed of the nipping surface 130a on the horn 130 side by an amount of reduction of the radius of rotation R160a of the nipping surface 160a on the anvil 160 side due to the above-mentioned pushing. Then, the portion of the continuous web 1a nipped by these

nipping surfaces

130a and 160a will have a relative speed against at least one of the

nipping surfaces

130a and 160a, and as a result, fines may be produced by friction and creases may be produced in the continuous web 1a.

Also, at the time of applying ultrasonic vibration from the nipping surfaces 130a to the continuous web 1a, if the continuous web 1a is sliding relative to the

nipping surfaces

130a and 160a, the welding process may become unstable.

Further, as shown in Fig. 2, the transport track Tr1a of the continuous web 1a is of a linear trajectory, whereas a trajectory of the nipping surface 130a on the horn 130 side and a trajectory of the nipping surface 160a on the anvil 60 side at the intersecting track section TrC are an arc that is downwardly convex and an arc that is downwardly concave, respectively, and such an inconformity between these track shapes may be one of the causes of the relative slippage between the continuous web 1a and the

nipping surfaces

130a, 160a, and may promote the above-mentioned production of the fines or creases and the unstableness of the welding process.

The present invention has been made in view of such a problem and its object is to suppress the relative speed (relative slippage) between the ultrasonic vibration, the anvil and the continuous web during the welding process, to suppress the generation of the fines and creases, and to form the welded section in a stable manner.

In order to achieve the objects described above, the main aspect of the present invention is:

an ultrasonic sealing apparatus that forms a plurality of welded sections at intervals along a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article, the apparatus including,
an ultrasonic horn that emits the ultrasonic vibration;
an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web; and
a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track,
the forward path having an equal speed region in which the ultrasonic horn and the anvil oppose each other in the thickness direction and move at a speed value which is the same as a transport speed value of the continuous web,
the ultrasonic horn and the anvil performing a nipping and a releasing of the nipping of the continuous web while moving in the equal speed region,
the ultrasonic horn emitting the ultrasonic vibration during the nipping of the continuous web.

Also provided is an ultrasonic sealing method that forms a plurality of welded sections at intervals in a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article, the method including:
using
an ultrasonic horn that emits the ultrasonic vibration,
an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web, and
a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track,
moving, in the forward path, the ultrasonic horn and the anvil at a speed which is the same as the transport speed of the continuous web with the ultrasonic horn and the anvil opposing each other in the thickness direction;
nipping the continuous web with the ultrasonic horn and the anvil, in the moving at the same speed;
releasing the nipping, in the moving at the same speed; and
emitting the ultrasonic vibration with the ultrasonic horn during the nipping.

According to an aspect of the invention, the relative speed (relative slippage) between the ultrasonic vibration, the anvil and the continuous web during the welding process can be suppressed, the generation of the fines and creases can be suppressed, and to form the welded section in stable manner.

Fig. 1 is a schematic side view of a conventional ultrasonic sealing apparatus 120 illustrating how a welding process is performed in a series, (A) to (F). Fig. 2 is an explanatory diagram for the conventional ultrasonic sealing apparatus 120 illustrating that a relative speed is produced between a base material 1a, an ultrasonic horn 130 and an anvil 160 when the base material 1a is nipped between a nipping surface 130a of the ultrasonic horn 130 and a nipping surface 160a of the anvil 160. Fig. 3A is an explanatory perspective view of the base material 1a of a diaper 1 that is transported to a sealing section provided with an ultrasonic sealing apparatus 20 of a first embodiment. Fig. 3B is another explanatory perspective view of the base material 1a of a diaper 1 that is transported to a sealing step provided with an ultrasonic sealing apparatus 20 of a first embodiment. Fig. 4A is a schematic side view of the ultrasonic sealing apparatus 20 of the first embodiment; Fig. 4B is a view taken along arrow line B-B; and Fig. 4C is a view taken along arrow line C-C. Fig. 5A is a partially cutaway enlarged side view illustrating an anvil 60 located at a withdrawn position. Fig. 5B is a partially cutaway enlarged side view illustrating the anvil 60 located at a nipping position. Fig. 6 is a schematic perspective view of a lower surface 60d of the anvil 60 seen from an obliquely downward position. Fig. 7 is an explanatory diagram of data for an operating pattern of a reciprocating operation in a front-back direction of the ultrasonic horn 30 and the anvil 60 in which an upper graph shows data for the ultrasonic horn 30 and a lower graph shows data for the anvil 60. Fig. 8 is an explanatory diagram of an operating pattern for an S-size and an L-size in which an upper graph shows data for the ultrasonic horn 30 and a lower graph shows data for the anvil 60. Fig. 9 is a schematic side view of an ultrasonic sealing apparatus 20a of a second embodiment. Fig. 10 is an explanatory diagram of data for an operating pattern for a rear module 20M and data for an operating pattern for a front module 20M. Fig. 11 is a diagrammatic view illustrating, in a series from (A) to (J), that both a rear module 20M and a front module 20M of a third embodiment are forming a welded section 14 on a base material 1a by reversely operating with each other. Fig. 12 is an explanatory diagram of data for an operating pattern for a rear module 20M and data for an operating pattern for a front module 20M.

At least the following matters will be disclosed in the present specification and accompanying drawings.

Provided is an ultrasonic sealing apparatus that forms a plurality of welded sections at intervals along a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article, the apparatus including,
an ultrasonic horn that emits the ultrasonic vibration;
an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web; and
a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track,
the forward path having an equal speed region in which the ultrasonic horn and the anvil oppose each other in the thickness direction and move at a speed value which is the same as a transport speed value of the continuous web,
the ultrasonic horn and the anvil performing a nipping and a releasing of the nipping of the continuous web while moving in the equal speed region,
the ultrasonic horn emitting the ultrasonic vibration during the nipping of the continuous web.

With such an ultrasonic sealing apparatus, within the equal speed region, both the ultrasonic horn and the anvil move at the same speed value as the continuous web and along the linear track of the continuous web, and perform the nipping of the continuous web and the releasing thereof. Accordingly, since the welding process is performed in a state where the speed values of the continuous web, the ultrasonic horn and the anvil are equal, a relative speed (relative slippage) between the three can be suppressed. As a result, friction and production of creases can be suppressed and also the welded section can be formed in a stable manner.

In the above-mentioned ultrasonic sealing apparatus, a plurality of modules may be arranged along the linear track, each of the modules having the ultrasonic horn, the anvil and the reciprocating linear motion mechanism.

It is preferable that in the above-mentioned ultrasonic sealing apparatus,
the plurality of modules includes at least a first module and a second module,
a reciprocating linear motion mechanism of the second module carries out a motion in a backward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a forward path, and
a reciprocating linear motion mechanism of the second module carries out a motion in a forward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a backward path.

With such an ultrasonic sealing apparatus, the first module and the second module are in a relationship performing substantially a reverse operation against each other with respect to the reciprocating motion of the ultrasonic horn and the anvil. Therefore, due to the reciprocating motion of the ultrasonic horn and the anvil, inertial forces may be cancelled out that may be exerted on a supporting member such as a panel supporting the first module and the second module, and as a result, mechanical vibration which may be produced in a member provided around the first module and the second module can be reduced.

In the above-mentioned ultrasonic sealing apparatus,
the plurality of modules may include at least a first module and a second module,
a reciprocating linear motion mechanism of the second module may carry out a motion in a forward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a forward path,
a reciprocating linear motion mechanism of the second module may carry out a motion in a backward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a backward path.

It is preferable that in the above-mentioned ultrasonic sealing apparatus,
during the nipping, the ultrasonic horn applies a pre-set amount of energy of the ultrasonic vibration to the continuous web.

With such an ultrasonic sealing apparatus, during the nipping, the ultrasonic horn applies a pre-set amount of energy of the ultrasonic vibration to the continuous web. Therefore, the fluctuation of the welding level for each welded section due to variation of the transport speed of the continuous web can be effectively prevented, and as a result, the welded section having a predetermined welding strength can be formed in a stable manner.

It is preferable that the above-mentioned ultrasonic sealing apparatus further includes a controller that controls the reciprocating linear motion mechanism, wherein,
under the control of the controller, the reciprocating linear motion mechanism repeatedly moves the ultrasonic horn and the anvil along the forward path and the backward path based on a predetermined operating pattern,
the controller has a plurality of data items relating to the operation pattern, the plurality of data items being different from each other,
the controller selects, from among the plurality of data items relating to the operating pattern, a data item relating to an operating pattern corresponding to a size of a formation pitch in the transport direction of the welded section to be formed, and uses the selected data item to control the reciprocating linear motion mechanism.

With such an ultrasonic sealing apparatus, the controller selects data relating to the operation pattern corresponding to the size of the formation pitch of the welded section to be formed, and the reciprocating linear motion mechanism is controlled based on the data relating to the selected operation pattern. Thus, the formation pitch of the welded sections can be altered in a facilitated manner.

It is preferable that in the above-mentioned ultrasonic sealing apparatus,
an up-down direction of the apparatus is orthogonal to the linear track, and the anvil is located above the ultrasonic horn in the up-down direction.

With such an ultrasonic sealing apparatus, maintenance of the movable sections of the anvil 60 can be carried out in a facilitated manner.

It is preferable that in the above-mentioned ultrasonic sealing apparatus,
the anvil is configured to be movable in the up-down direction, and the ultrasonic horn is configured to be immovable in the up-down direction.

With such an ultrasonic sealing apparatus, the number of movable sections for the nipping operation can be reduced because the ultrasonic horn is configured to be immovable in the up-down direction.

It is preferable that in the above-mentioned ultrasonic sealing apparatus,
the anvil is configured to be immovable in the up-down direction, and the ultrasonic horn is configured to be movable in the up-down direction.

With such an ultrasonic sealing apparatus, the number of movable sections for the nipping operation can be reduced because the anvil is configured to be immovable in the up-down direction.
In such an ultrasonic sealing apparatus,
both the anvil and the ultrasonic horn may be configured to be movable in the up-down direction.

Also provided is an ultrasonic sealing method that forms a plurality of welded sections at intervals in a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article, the method including:
using
an ultrasonic horn that emits the ultrasonic vibration,
an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web, and
a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track,
moving, in the forward path, the ultrasonic horn and the anvil at a speed value which is the same as the transport speed value of the continuous web with the ultrasonic horn and the anvil opposing each other in the thickness direction;
nipping the continuous web with the ultrasonic horn and the anvil, in the moving at the same speed;
releasing the nipping, in the moving at the same speed; and
emitting the ultrasonic vibration with the ultrasonic horn during the nipping.

With such an ultrasonic sealing method, in the moving of the ultrasonic horn and the anvil at the same speed value as the transport speed value of the continuous web, these two perform the nipping of the continuous web and the releasing of the nipping while moving along the linear track of the continuous web. Therefore, since the welding process is performed by nipping in a state where the speed values of the continuous web, the ultrasonic horn and the anvil have the same value, the relative speed (relative slippage) between the three can be suppressed. As a result, the production of rubbing or creases can be suppressed and the welded section can be formed in a stable manner.

First Embodiment
An ultrasonic sealing apparatus 20 of the present invention is an apparatus that forms a plurality of welded sections 14 on a continuous web 1a which is being transported in a continuous production line, in such a manner that the welded sections 14 are formed in a spaced apart manner at a predetermined pitch P1 along a transport direction of the continuous web 1a. In the first embodiment, a base material 1a of a pants-type diaper 1 is shown as an example of the continuous web 1a.

Figs. 3A and 3B are explanatory diagrams, each being a perspective view, of the base material 1a of the diaper 1 which is being transported to a sealing section provided with the ultrasonic sealing apparatus 20 (Fig. 4A). Fig. 3B illustrates a state immediately before transportation to the sealing process and Fig. 3A illustrates a state immediately before Fig. 3B.

At the point shown in Fig. 3A, the base material 1a of the diaper 1 includes a continuous web 2a which will be a front sheet 2 to be placed on a wearer's skin side; a continuous web 3a which will be a back sheet 3 to be placed on a non-skin side; and absorbent bodies 4, 4... of pulp fiber or the like that are sandwiched between the continuous webs 2a and 3a and arranged in a spaced apart manner along a transport direction at a product pitch P1. These three components, i.e., 2a, 3a and 4, are bonded together in such a manner that adjacent ones are bonded to each other and are in an open state. The invention is not limited to the use of these three components 2a, 3a and 4.

Also, at this point, a leg opening section 8 is already formed between the absorbent bodies 4, 4 that are adjacent to each other in the transport direction. An elastic member 6 that provides stretchability to the leg opening 8 is adhered along the leg opening section 8 and along an inseam section 13. Further, a waist elastic member 5 that provides stretchability around the waist is adhered along an end section corresponding to the waist. The invention is not limited to the use of these components 5 and 6.

Immediately before the sealing section, the base material 1a, in an open state as shown in Fig. 3A, is folded in half along the inseam section 13 which is a substantially central section in its width direction, and thus the base member 1a is sent to the sealing section in a half-fold state as shown in Fig. 3B. In other words, a portion corresponding to a front piece 10 of the diaper 1 and a portion corresponding to a back piece 11 are sent to the sealing section in a state where they are layered on top of each other.

It is to be noted that the base material 1a of the diaper 1 at this point is in a state where the portion corresponding to the front piece 10 of the diaper 1 and the portion corresponding to the back piece 11 that are layered on top of each other have not yet been joined. Therefore, the ultrasonic sealing apparatus 20 in the sealing section applies a welding process to the base material 1a at a portion 1e corresponding to a side end section 1e around the waist of the diaper 1 and forms the welded section 14, and thus the front piece 10 and the back piece 11 of the base material 1a are joined with each other. The invention is not limited to welding of the base material 1a or to welding at this position.

Here, the portion to be welded 1e, i.e., the portion 1e corresponding to the side end section around the waist of the diaper 1, appears on either side of the absorbent body 4 on the base material 1a along the transport direction at the product pitch P1. Accordingly, the ultrasonic sealing apparatus 20 forms the welded sections 14 at the portions 1e of the base material 1a on both sides of the absorbent body 4 with a product pitch P1 in the transport direction. As shown in Fig. 3B, such welded sections 14 are formed in such a manner that, for one of the sections 1e, at least a pair of welded

sections

14, 14 are arranged side-by-side at positions adjacent to each other in the transport direction. Then, the base material 1a in which such welded sections 14 are formed is sent to a downstream process, and in the downstream process, the base material 1a is sequentially divided at a location 1c between the pair of welded

sections

14, 14, thereby forming the diaper 1 having the waist opening and the pair of

leg openings

8,8.

It is to be noted that an example of a raw material of the continuous web 2a of the front sheet 2 and the continuous web 3a of the back sheet 3 includes nonwoven fabric, woven fabric or a film made of a thermally weldable material such as a thermoplastic resin, but it is not limited thereto as long as it is a material capable of being ultrasonically welded. The invention is not limited to use of this process for manufacturing the diaper 1.

Fig. 4A is a schematic side view of the ultrasonic sealing apparatus 20; Fig. 4B is a view taken along arrow line B-B in Fig. 4A; and Fig. 4C is a view taken along arrow line C-C in Fig. 4A. In Fig. 4A, an anvil retaining section 72 or the like is illustrated in a cut-away view, and in Figs. 4A and 4C, in order to avoid confusion between the drawings, hatchings that should be provided on cross-sectional parts are omitted for some of the members.

In the following description, a width direction of the production line is also referred to as "CD-direction" or "right-left direction". The CD-direction is oriented in a horizontal direction. Regarding the two directions that are orthogonal to the CD-direction, a vertical direction is also referred to as an "up-down direction", and a horizontal direction is also referred to as a "front-back" direction. It is to be noted that the right-left direction, the up-down direction and the front-back direction are in a mutually orthogonal relationship.

In this ultrasonic sealing apparatus 20, the base material 1a is continuously transported in the transport direction at a predetermined transport speed value V1a by a transport apparatus 90 such as a transport roller 90. In this example, the base material 1a is transported along a linear track Tr1a, whose transport direction is the front-back direction, with a thickness direction being oriented in an up-down direction and a width direction being oriented in a right-left direction. In other words, the base material 1a is transported with the linear track Tr1a in the front-back direction being the transport track Tr1a.

It is to be noted that a controller (not shown) that controls the transport apparatus 90 receives a synchronization signal in order to synchronize with other devices on the production line and performs a transport operation based on the synchronization signal. This synchronization signal is outputted from a sensor such as a rotary encoder that measures a transport amount of the base material 1a in, for example, a device taken as a reference in the production line (e.g., a rotary die cutter device that forms the leg opening 8 by stamping). The synchronization signal is a rotational angle signal expressed by, for example, taking a transport amount of a single diaper, which is a product, (i.e., product pitch P1) as a unit transport amount, and allocating each rotational angle value between 0^O and 360^O in proportion to the transport amount. In other words, when the transportation is performed by an amount of a single diaper, a rotational angle value between 0^O and 360^O is outputted, and an output of the rotational angle value of 0^O to 360^O is periodically repeated every time such a transportation of the relevant single diaper is performed. It is to be noted that the synchronization signal is not limited to the rotational angle signal. For example, a digital signal may be used as the synchronization signal that is obtained by allotting each of the digital values for 0-8191 to the above-mentioned unit transport amount in proportion to the transport amount. Also, using a pulse signal as a synchronization signal that has a number of pulses in proportion to the transport amount, the rotational angle may be detected by counting the number of pulses in the signal.

As shown in Fig. 4A, the ultrasonic sealing apparatus 20 includes an ultrasonic horn 30 that is located below the linear transport track Tr1a of the base material 1a; an anvil 60 that is located above the transport track Tr1a; a front-back direction reciprocating linear motion mechanism that moves the ultrasonic horn 30 and the anvil 60 along a forward path Fp and a backward path Bp that are parallel to the transport track Tr1a of the base material 1a; a nipping drive mechanism that causes the ultrasonic horn 30 and the anvil 60 to nip the base material 1a in the up-down direction which is the width direction; and a controller 80 that controls those mechanisms.

Here, the above-mentioned forward path Fp is directed towards the front direction which is a downstream side in the transport direction of the base material 1a. In a substantially central region in the forward path Fp, a constant speed region Re is provided in which both the ultrasonic horn 30 and the anvil 60 move at the same speed value as the transport speed value V1a of the base material 1a in a state where they are opposing each other in the thickness direction. Also, while moving in the constant speed region Re, the ultrasonic horn 30 and the anvil 60 nip, and release the nipping of, the base material 1a, and further, during the nipping, the ultrasonic horn 30 emits ultrasonic vibration.

Therefore, with this ultrasonic sealing apparatus 20, a welding process can be performed by nipping the base material 1a in a state where the moving speeds in the front-back direction of the base material 1a, the ultrasonic horn 30 and the anvil 60 are the same. In other words, since a relative speed (relative sliding) between the three components, i.e., 30, 60 and 1a, during the welding process can be suppressed, the welded sections 14 can be formed in a stable manner while suppressing rubbing or generation of creases in the base material 1a.

It is to be noted that, after the above-mentioned welding process, the ultrasonic vibration is ceased and the nipping is released successively before the ultrasonic horn 30 and the anvil 60 leave the constant speed region Re, and thereafter, the ultrasonic horn 30 and the anvil 60 promptly reverse the moving direction from a forward path direction to a backward path direction, and start a moving operation in the backward path Bp. Then, in the motion in the backward path Bp, upon reaching a backward limit Pb, which is a starting end position in the forward path Fp, the moving direction is reversed from the backward path Bp to the forward path Fp again and a moving operation in the forward path Fp is started, and thereafter, a series of operations related to the welding process starting from the above-mentioned moving operation in the forward path Fp is performed. By repeating them, the welded sections 14 are formed in a spaced apart manner at the product pitch P1 in the front-back direction, which is the transport direction, on the base material 1a.

Hereinafter, the ultrasonic sealing apparatus 20 will be described in detail.

The ultrasonic sealing apparatus 20 is, for example, supported in a cantilevered manner on a panel 19 serving as a supporting member and provided in the production line in an upright manner resembling a wall surface. In other words, the panel 19 is provided on one side (for example, on the left side) in the CD-direction of the production line and extends in the up-down direction and the front-back direction, and supports the ultrasonic sealing apparatus 20 with its vertical surface 19a serving as a supporting surface.

Now, in addition to the above-mentioned segmentation of the components, the ultrasonic sealing apparatus 20 may be segmented into the following components. That is, the ultrasonic sealing apparatus 20 includes an ultrasonic horn unit 30U provided with the ultrasonic horn 30, an anvil unit 60U provided with the anvil 60 and the controller 80. In the following description, for the sake of convenience, the description will be made based on the segmentation into the

components

30U, 60U and 80. Those components corresponding to the "front-back direction linear motion mechanism" and the "nipping drive mechanism" in the above-mentioned segmentation of components will be described below when the corresponding components come up in the specification.

Ultrasonic Horn Unit 30U
The ultrasonic horn unit 30U includes: a horizontal floor board 32 secured to the panel 19 in such a manner that it is not relatively movable with respect to the panel 19 in order to support various devices associated with the ultrasonic horn unit 30U; a guiding member 40 that is provided on an upper surface of the floor board 32 and guides the ultrasonic horn 30 in a reciprocably movable manner along the linear track in a front-back direction; and a front-back direction driving mechanism 50 that is provided on a top surface of the floor board 32 and applies, to the ultrasonic horn 30, a driving force related to the reciprocating motion in the front-back direction. It is to be noted that the above-mentioned guiding member 40 and the front-back direction driving mechanism 50 correspond to the "front-back direction reciprocating linear motion mechanism".

The floor board 32 is secured to the panel 19 at a one-end edge (left-end edge) in the CD-direction and thus supported in a cantilevered manner.

The guiding member 40 is, for example, a linear guide 40. That is to say, it includes a pair of left and

right rails

42, 42 extending along the front-back direction and secured to a top surface of the floor board 32 in such a manner that they are not relatively movable with respect to the top surface, and also includes

sliders

44, 44 provided for the

rails

42, 42, respectively, and engaged with the

rails

42, 42 so as to be reciprocable in the front-back direction, only. The ultrasonic horn 30 is secured to the

sliders

44, 44 via an appropriate supporting table 46 in such a manner that it is not relatively movable, and thus the ultrasonic horn 30 and the

sliders

44, 44 are integrated and guided in such a manner that they are reciprocable in the front-back direction.

The front-back direction driving mechanism 50 includes a motor 52 and a feed screw mechanism 56. The feed screw mechanism 56 converts a rotational motion of a driving rotational axis 52a of the motor 52 into a front-back direction linear motion operation and transfers it to the ultrasonic horn 30, and a ball screw mechanism 56 is used here. In other words, a screw shaft 57 of the ball screw mechanism 56 is arranged with its axial direction lying along the front-back direction, and in this state, the screw shaft 57 is supported at both its end sections in a rotatable manner by bearing

members

59, 59 on a top surface of the floor board 32. A nut member 58 screws into a spiral groove (not shown) on an outer peripheral surface of the screw shaft 57 via a plurality of ball-like rolling elements (not shown), and the ultrasonic horn 30 is secured to the nut member 58 via the above-mentioned supporting table 46. Further, the driving rotational axis 52a of the motor 52 and the screw shaft 57 are concentrically linked via an appropriate coupling 55. Therefore, when the rotational operation of the driving rotational axis 52a of the motor 52 is transferred to the screw shaft 57 and the screw shaft 57 is rotated, the ultrasonic horn 30 and the nut member 58 moves in the front-back direction in an integrated manner.

The motor 52 is, for example, a servo motor 52 and carries out a position control based on a position instruction signal (control signal) which is transmitted from outside. In other words, the servo motor 52 includes an amplifier (not shown) provided with a position detecting element that is capable of detecting its actual position. Accordingly, with any position in the front-back direction being provided as a target position, the servo motor 52 can move the ultrasonic horn 30 to the target position in the front-back direction based on a feedback signal or the like of the actual position from the position detecting element of the amplifier. It is to be noted that such a target position is transmitted to the servo motor 52 in a form of the position instruction signal from the controller 80, and the servo motor 52 operates based on this position instruction signal.

As shown in enlarged side views in Figs. 5A and 5B, the ultrasonic horn 30 has a horizontal flat nipping surface 30a that is adjacent to and opposes a lower surface of the base material 1a so as to nip the base material 1a in its thickness direction in cooperation with the anvil 60. Ultrasonic vibration produced in an accessorized ultrasonic vibration generating device 31 is transferred to the nipping surface 30a, and thus, as shown in Fig. 5B, the ultrasonic vibration is applied to the base material 1a that is nipped in cooperation with the anvil 60. Then, a nipped portion of the base material 1a melts by an action such as generation of heat by friction due to ultrasonic vibration, and the welded section 14 is formed at such a portion.

Generation of such ultrasonic vibration is initiated based on an appropriate trigger signal, and the generation is ceased by the ultrasonic vibration generating apparatus 31, which has detected that a predetermined amount of energy (Joule) which had been set in advance has been applied. Accordingly, fluctuation of a melting level between the welded sections 14 due to variation in a transport speed V1a of the base material 1a can be prevented, and as a result, the welded sections 14 having a predetermined welding strength can be formed stably. It is to be noted that the above-mentioned trigger signal that specifies a generation initiating timing may be, for example, generated by the controller 80 and sent to the ultrasonic vibration generating apparatus 31, or, generated by the ultrasonic vibration generating apparatus 31 that receives a synchronization signal and self-determines the generation initiating timing of the trigger signal from the synchronization signal. It is to be noted that, in the first embodiment, the controller 80 generates an ultrasound generating instruction signal as the trigger signal and sends it to the ultrasonic vibration generating apparatus 31. The sending timing of the ultrasound generating instruction signal will be described later.

Anvil Unit 60U
The anvil unit 60U includes a horizontal top board 62 secured to the panel 19 in such a manner that it is not relatively movable with respect to the panel 19 in order to support various devices related to the anvil unit 60U; a guiding member 40AN that is provided on a lower surface of the top board 62 and guides the anvil 60 along the linear track in a reciprocable manner in the front-back direction; a front-back direction driving mechanism 50AN that applies a driving force related to the front-back direction reciprocating motion to the anvil 60; and an up-down direction reciprocation mechanism 70 that reciprocally moves the anvil 60 in the up-down direction, which is the thickness direction of the base material 1a, in order to nip the base material 1a in cooperation with the ultrasonic horn 30. It is to be noted that the above-mentioned guiding member 40AN and the front-back direction driving mechanism 50AN correspond to the "front-back direction reciprocating linear motion mechanism" and the up-down direction reciprocation mechanism 70 corresponds to the "nipping driving mechanism".

The top board 62 is secured to the panel 19 at one-end edge (left-end edge) in the CD-direction and it is thus supported in a cantilevered state. The guiding member 40AN and the front-back direction driving mechanism 50AN are provided on a lower surface of the top board 62. The basic structures of these guiding member 40AN and the front-back direction driving mechanism 50AN are substantially the same as those 40, 50 of the above-mentioned ultrasonic horn unit 30U. In other words, the guiding member 40AN and the front-back direction driving mechanism 50AN of the anvil unit 60U are substantially the same as the linear guide 40 serving as the guiding member 40 of the above-mentioned ultrasonic horn unit 30U and the ball screw mechanism 56 serving as the feed screw mechanism of the front-back direction driving mechanism 50 that are turned upside down and secured to the lower surface of the top board 62. Therefore, as has already been indicated above, various components associated with the guiding member 40AN and the front-back direction driving mechanism 50AN of the anvil unit 60U are represented with reference numerals with "AN" further added at an end of the same reference numeral of the various components of the ultrasonic horn unit 30U, and descriptions thereof are omitted, since they mainly differ from the guiding member 40 and the front-back direction driving mechanism 50 of the ultrasonic horn unit 30U for the above-mentioned points and other points are substantially of the same configuration.

As shown in Fig. 4A, the linear guide 40AN and the ball screw mechanism 56AN of the anvil unit 60U are arranged directly above the linear guide 40 and the ball screw mechanism 56 of the ultrasonic horn unit 30U in such a manner that they cooperate with the linear guide 40 and the ball screw mechanism 56 of the ultrasonic horn unit 30U to sandwich the transport track Tr1a of the base material 1a from above and from below (in the thickness direction). Accordingly, the anvil 60 which is suspended from a slider 44AN of the linear guide 40 of the anvil unit 60U is arranged at a position above the base material 1a in such a manner that it opposes the ultrasonic horn 30 across the base material 1a. Therefore, by controlling a servo motor 52AN of the ball screw mechanism 56AN of the anvil unit 60U to operate in cooperation with the servo motor 52 of the ball screw mechanism 56 of the ultrasonic horn unit 30U, the anvil 60 can be moved in cooperation with the ultrasonic horn 30 in a reciprocating manner in the front-back direction while maintaining an opposing state with the ultrasonic horn 30.

Figs. 5A and 5B are enlarged side views illustrating the anvil 60 and the ultrasonic horn 30.

As shown in Fig. 5A, an up-down direction reciprocating mechanism 70 (corresponds to a thickness direction reciprocating mechanism) that reciprocates the anvil 60 in the up-down direction includes an anvil retaining section 72 that retains the anvil 60 in a relatively movable manner in the up-down direction. This anvil retaining section 72 is secured to the sliders 44AN, 44AN of the linear guide 40 via an appropriate supporting table 76 so as not to be relatively movable, and thus the retaining section 72 reciprocates in the front-back direction in an integrated manner with the sliders 44AN, 44AN.

The anvil retaining section 72 includes, for example, a box member 72 serving as a main body and the anvil 60 is accommodated in an inner space thereof with a clearance corresponding to the above-mentioned reciprocating motion in the up-down direction. Also, a lower surface wall section 72d of the box member 72 is provided with a through hole 72h formed therein that is somewhat greater than a cross sectional configuration of the anvil 60 so as to let the lower surface 60d of the nipping surface 60a of the anvil 60 protrude outwards. Further, the anvil 60 has a flange section 60f protruding annularly and laterally from its upper end section, and the flange section 60f is configured to engage with a peripheral section of the through hole 72h of the lower surface 60d of the box member 72. Then, with such an engagement, an amount of downward displacement of the anvil 60 is limited to a predetermined amount and, in other words, the anvil 60 is allowed to move upwardly and downwardly between predetermined upper and lower limit positions.

Here, as shown in Fig. 5A, at an upper limit position, the anvil 60 opposes the base material 1a situated below with a predetermined gap therebetween. In other words, it is not in contact with the base material 1a. On the other hand, as shown in Fig. 5B, when lowering from the upper limit position to the lower limit position as indicated with a white arrow, the anvil 60 comes into contact with the base material 1a and further pushes the base material 1a downwards and thus the anvil 60 comes to a state where it cooperates with a nipping surface 30a of the ultrasonic horn 30 to nip the base material 1a with a predetermined nipping force. When this nipping state is reached, any further downward movement is stopped by the ultrasonic horn 30, and, in practice, the anvil 60 does not lower down to the lower limit position. Hereinafter, the upper limit position is also referred to as "a withdrawn position" and a position where the nipping state is achieved during the movement to the lower limit position is also referred to as "a nipping position".

On the other hand, as shown in Fig. 5A, a drive source, such as an air spring 74, that moves the anvil 60 in the up-down direction is interposed between a lower surface 72ud of an upper wall section 72u of such an anvil retaining section 72 and an upper surface 60u of the anvil 60 (a surface of the anvil 60 opposite to the nipping surface 60a of the lower surface 60d). The air spring 74 has a sealed bag body 74 as a main body. The bag body 74 inflates when internally pressurized by an air supply and deflates when internally depressurized by ejection of air. Further, a compression spring 75 is interposed between the lower surface wall section 72d of the anvil retaining section 72 and the flange section 60f of the anvil 60, and the anvil 60 is always pressed towards the upper surface wall section 72u (i.e., upwards) due to its restoring force. Therefore, by supplying and ejecting air to and from the air spring 74 by cooperating with the compression spring 75, the anvil 60 can be moved with respect to the anvil retaining section 72 in a reciprocating manner in the up-down direction. In other words, by pressurizing the air spring 74 by supplying the air, the anvil 60 moves downwardly due to inflation of the air spring 74 and reaches the nipping position, and thereby cooperates with the lower ultrasonic horn 30 to nip the base material 1a (Fig. 5B). On the other hand, when the air spring 74 is depressurized by ejecting the air, the anvil 60 is pushed back upwardly due to the restoring force of the compression spring 75 and thus returns to the withdrawn position, which is the upper limit position (Fig. 5A).

An example of a mechanism for achieving air supply/ejection control for such an air spring 74 may be a configuration in which a compression air source such as a compressor (not shown) is connected to the air spring 74 via an air channel such as a duct, and a regulator (not shown) such as a pressure adjustment valve is provided on the above-mentioned air channel between the compression air source and the air spring 74.

It is to be noted that the air supply/ejection operation is carried out in accordance with an appropriate control signal. The control signal may be, for example, generated by the controller 80 and transmitted to the above-mentioned regulator, or, may be generated by the regulator itself, which is receiving a synchronization signal, by determining a supply/ejection operation timing from the synchronization signal. According to the first embodiment, the controller 80 generates a supply/ejection instruction signal that serves as a control signal and sends it to the regulator. This supply/ejection signal is, for example, an ON/OFF signal. When an ON state is received, the regulator is brought to a pressurizing state and this state is maintained while receiving the ON state, and on the other hand, when an OFF state is received, it is brought to a depressurizing state and this state is maintained while receiving the OFF state. It is to be noted that, in other words, "while the supply/ejection instruction signal is in an ON state, the anvil 60 is in a nipping state where it nips the base material 1a and while the supply/ejection instruction signal is in an OFF state, the anvil 60 is in a withdrawn state where the nipping of the base material 1a is released." Therefore, in the following description, such a supply/ejection instruction signal is also referred to as "a nipping instruction signal."

It has been briefly described above that the nipping surface 60a of the anvil 60 is provided on the lower surface 60d of the anvil 60 so as to be capable of opposing the nipping surface 30a of the ultrasonic horn 30 situated below, and, the nipping surface 60a will now be described in detail. Fig. 6 is a schematic perspective view of the lower surface 60d of the anvil 60 seen from an obliquely downward position. The lower surface 60d of the anvil 60 is provided with a pair of front-

back ribs

61, 61 formed thereon along the right-left direction, i.e., the CD-direction, in such a manner that they correspond to a shape pattern (Fig. 3) of the pair of front-back welded

sections

14, 14 which are to be formed on the base material 1a. A plurality of protruded

sections

61a, 61a... are formed on a surface of each rib 61 along a longitudinal direction of the rib 61 and at a predetermined pitch, and the respective top surfaces of the protruded

sections

61a, 61a,... serve as the nipping surface 60a of the anvil 60. However, this has been indicated by way of example only, and a nipping surface 60a of another configuration may also be used.

Controller 80
The controller 80 is an appropriate computer or sequencer and includes a processor and a memory which are not shown in the figures. The above-mentioned synchronization signal is inputted to the controller 80. Based on the synchronization signal, the controller 80 controls the respective front-back direction driving mechanism 50, 50AN of the ultrasonic horn unit 30U and the anvil unit 60U, and the up-down direction reciprocation mechanism 70 of the anvil 60. For example, the position instruction signal is sent as the control signal to amplifiers of the

servo motors

52,52 of the respective front-back driving mechanisms 50, 50AN of the ultrasonic horn unit 30U and the anvil unit 60U, whereas the nipping instruction signal (supply/ejection instruction signal) is sent as the control signal to the regulator of the air spring 74 of the up-down direction reciprocation mechanism 70 of the anvil unit 60U, and further, an ultrasound generation instruction signal is sent as the control signal to the ultrasonic vibration generating apparatus 31 of the ultrasonic horn unit 30U.

It is to be noted that a control program related to the above-mentioned control is pre-stored in the memory of the controller 80. Further pre-stored in this memory is data of an operation pattern specifying the front-back direction reciprocating motion operation of the ultrasonic horn 30 and the anvil 60, data specifying the ON/OFF state of the nipping instruction signal, and data specifying a transmission timing of the ultrasound generation instruction signal. With the processor appropriately reading out and executing the corresponding control program or data occasionally from the memory, the control of the respective front-back direction driving mechanism 50 of the above-mentioned ultrasonic horn unit 30U and the anvil unit 60U, the control of the up-down direction reciprocation mechanism 70 related to the anvil unit 60U, as well as the control of the ultrasonic vibration generating apparatus 31 related to the ultrasonic horn unit 30U, can be achieved.

Fig. 7 is an explanatory diagram of data of an operation pattern of the front-back direction reciprocating motion operation of the ultrasonic horn 30 and the anvil 60 (a pattern indicating a correspondence relationship between a front-back direction target position of the ultrasonic horn 30 and the anvil 60, and a rotational angle value of the synchronization signal) in which the top diagram indicates data for the ultrasonic horn 30 and the bottom diagram indicates data for the anvil 60. A vertical axis represents the target position in the front-back direction, and a forward limit Pf is provided at the front and a backward limit Pb is provided at the back. Of course, in the forward path, motion is from the backward limit Pb to the forward limit Pf and, in the backward path, motion is from the forward limit Pf to the backward limit Pb. A horizontal axis represents the rotational angle value corresponding to the synchronization signal and, in other words, a unit transport amount, which is a transport amount through the product pitch P1 of the base material 1a, is allotted to each value between 0^O and 360^O. It is to be noted that 360^O is also 0^O.

Further, in Fig. 7, an ON/OFF state of the nipping instruction signal related to the up-down reciprocating motion of the anvil 60 (supply/ejection instruction signal) and a first rotational angle value, which is data specifying a sending timing of an ultrasound generating instruction signal related to the ultrasonic horn 30, are also indicated.

The controller 80 acquires the target position corresponding to the rotational angle value of the synchronization signal from the data of the above-mentioned operation pattern in the memory at a predetermined control cycle, and sends the data of the acquired target position as a position instruction signal to the amplifiers of the servo motors 52, 52AN of the respective front-back direction driving mechanisms 50, 50AN of the ultrasonic horn unit 30U and the anvil unit 60U. Then, the amplifiers of the respective servo motors 52, 52AN control the servo motors 52, 52AN to move the ultrasonic horn 30 and the anvil 60 to the target position of the position instruction signal, and thus both the ultrasonic horn 30 and the anvil 60 reciprocate in the operation pattern shown in Fig. 7.

Now, as can be seen by comparing the graph at the top with the graph at the bottom in Fig. 7, in this example, regarding the front-back direction reciprocating operation, an operation pattern of the ultrasonic horn 30 and an operation pattern of the anvil 60 are completely identical patterns without any positional offset between the rotational angle values through the entire range of the rotational angle value from 0^O to 360^O. Accordingly, the ultrasonic horn 30 and the anvil 60 are capable of reciprocating in the front-back direction by completely cooperating with each other while maintaining a state where the nipping surfaces 30a, 60a are opposing each other across the base material 1a.

Further, as shown in Fig. 7, the forward path includes a first acceleration/deceleration region, a constant speed region in which the motion is at a constant speed value, and a second acceleration/deceleration region. Similarly, the backward path includes a third acceleration/deceleration region, a constant speed region and a fourth acceleration/deceleration region. Here, the speed value of the constant speed region of the forward path is set to the same value as a transport speed value V1a in the front-back direction of the base material 1a. In other words, this constant speed region is an equal speed region Re in which the speed of the ultrasonic horn 30 and the anvil 60 is the same as the transport speed value V1a of the base material 1a. Also, within a substantially central region of such an equal speed region Re, an ON state of the nipping instruction signal is set for a predetermined range of rotational angle value RON. Further, a first rotational angle value at which an ultrasound generating instruction signal is sent to the ultrasonic vibration generating apparatus 31 is set in the above-mentioned range of rotational angle value RON where such an ON state is associated.

Accordingly, when the rotational angle value indicated with the synchronization signal comes into the above-mentioned range RON, the controller 80 switches the nipping instruction signal to the up-down direction reciprocation mechanism 70 of the anvil unit 60U from an OFF state to an ON state. Thereby, the anvil 60 located at the withdrawn position, which is the upper limit position, descends and cooperates with the nipping surface 30a of the ultrasonic horn 30 to nip the base material 1a. Then, when the rotational angle value of the synchronization signal exceeds the above-mentioned first rotational angle value, the controller 80 sends an ultrasound generating instruction signal to the ultrasonic vibration generating apparatus 31. Thereby, ultrasonic vibration is emitted from the nipping surface 30a of the ultrasonic horn 30, and a portion of the base material 1a nipped between the nipping surface 30a of the ultrasonic horn 30 and the nipping surface 60a of the anvil 60 melts and forms the welded section 14. It is to be noted that, as has been described above, the ceasing of the ultrasonic vibration is automatically performed by the ultrasonic vibration generating apparatus 31. For example, the ultrasonic vibration generating apparatus 31 cumulatively measures the applied amount of energy (Joules) for every welding process, and ceases when it is detected that the applied amount of energy has reached a specified set value. On the other hand, if the rotational angle value of the synchronization signal leaves the above-mentioned range RON, the controller 80 changes the nipping instruction signal to an OFF state. Thus, the anvil 60 ascends, and after having released the nipping state of the base material 1a, finally comes back to the withdrawn position that is the upper limit position, and then waits until the nipping instruction signal switches from the OFF state to the ON state.

Then, as can be clearly understood from the description above and Fig. 7, the above-mentioned range RON of the rotational angle value is completely included in the equal speed region Re of the forward path. Therefore, the nipping and the releasing thereof of the base material 1a is completely performed in a state where the front-back direction speed value of the ultrasonic horn 30 and the anvil 60 and the transport speed value V1a of the base material 1a are equal. Then, as a result, a relative speed is not produced between each other, rubbing or generation of creases can be suppressed, and the welded section 14 can be formed in a stable manner.

Now, in the example of Fig. 7, the operation pattern in the forward path and the operation pattern in the backward path are in a mirror-image relationship with the rotational angle value of 180^O being a border. In other words, except that the orientation is reversed, these operation patterns are identical concerning the shape of the pattern, but it is not limited thereto. For example, before the rotational angle value reaches 360^O, if the ultrasonic horn 30 and the anvil 60 can return to the backward limit Pb, the operation pattern in the backward path need not be in a mirror-image relationship with the operation pattern in the forward path.

Also, in an example of Fig. 7, the operation pattern in the front-back direction reciprocating operation is identical for the ultrasonic horn unit 30U and the anvil unit 60U, but it is not limited thereto. In other words, in the forward path, if the constant speed region Re, in which the front-back direction speed value of the ultrasonic horn 30 and the anvil 60 is the same value as the transport speed value V1a of the base material 1a, can be assured as the rotational angle value of the predetermined range, the operation pattern of the ultrasonic horn unit 30U and the operation pattern of the anvil unit 60U need not be completely identical.

Further, in the first embodiment, the controller 80 has data for the operation pattern of the reciprocating motion in the front-back direction separately for the ultrasonic horn unit 30U and the anvil unit 60U, but it is not limited thereto, and these two may share single data for the operation pattern. In such a case, the controller 80 sends a position instruction signal generated based on the single data for the operation pattern to both the ultrasonic horn unit 30U and the anvil unit 60U. Thus, the ultrasonic horn 30 and the anvil 60 can reciprocate in a completely synchronized manner.

In the production line of the disposable diaper 1, a so-called size change is commonly performed in which the product size of the diaper 1 to be produced is changed, and the first embodiment is easily adaptable to such a size change. For example, the memory in the controller 80 pre-stores the operation pattern illustrated in Fig. 7 for each of the product sizes such as "S", "M" and "L". Fig. 8 shows an example of a data for the operation patterns for size S and size L, and, as can be seen in Fig. 8, a distance DS and DL between the forward limit Pf and the backward limit Pb is different for size S and size L, and in other words, the above-mentioned distance D is greater for size L, which is the product size larger than size S.

When this distance D changes, an interval between the welded

sections

14 and 14 which are formed adjacent to each other in the front-back direction changes. Therefore, if the data for the relevant operation pattern is configured to be selectable by the controller 80 based on the product size to be produced, by changing the size of the front-back direction formation pitch of the welded sections 14 (i.e., an interval size between the welded

sections

14 and 14 adjacent to each other in the front-back direction), it is easily adaptable to a size change.

Further, depending of the product size, when it is desired to change the welding strength of the welded section 14, the above-mentioned ultrasonic vibration generating apparatus 31 may have set values of an amount of energy (Joules) to be applied and related to ultrasonic vibration so as to be capable of being set for each product size such as "S", "M" and "L", and the same ultrasonic vibration generating apparatus 31 may be configured to select the set value based on the product size. Needless to say, the set value of an amount of energy is greater for size L, which has a larger total area of welded sections 14 than size S.

An alternative method of changing the welding strength depending on the above-mentioned product size is, for example, to change, for every product size, the strength of the nipping force when nipping the base material 1a with the ultrasonic horn 30 and the anvil 60. As has been described above, the nipping force is produced by a pressurizing force exerted by the air spring 74. Therefore, for example, in order to achieve this, a regulator may be configured to be capable of setting the pressurizing force of the air spring 74 with a plurality of set values of mutually different values and to select a single set value from among the above-mentioned plurality of set values. It is to be noted that both changing of the pressurizing force depending on the product size and changing of the set value of the amount of energy of the ultrasonic vibration depending on the above-mentioned product size may be performed.

Second Embodiment
Fig. 9 is a schematic side view of an ultrasonic sealing apparatus 20a of a second embodiment.

The above-mentioned first embodiment includes the ultrasonic sealing apparatus 20 that has a module including a single set of the ultrasonic horn unit 30U and the anvil unit 60U, but it is not limited thereto, and, for example, a plurality of

modules

20M, 20M,... may be arranged along the transport track Tr1a of the base material 1a. In an example of Fig. 9, as an example of a plurality case, two

modules

20M and 20M are arranged in a row in the front-back direction. It is to be noted that, since other matters are substantially the same as the first embodiment, identical structures are provided with the same reference numerals and explanations thereof are omitted.

Here, the

modules

20M and 20M that align in the front-back direction are configured to perform mutually the same operation with regards to the reciprocating operation in the front-back direction of the respective ultrasonic horn 30 and the anvil 60. In other words, when the ultrasonic horn 30 and the anvil 60 of the rear module 20M move along the forward path in the front-back direction, the ultrasonic horn 30 and the anvil 60 of the front module 20M also move along the forward path, and when the ultrasonic horn 30 and the anvil 60 of the rear module 20M move along the backward path in the front-back direction, the ultrasonic horn 30 and the anvil 60 of the front module 20M also move along the backward path. Hereinafter, this is also referred to as a "forward operation".

The ultrasonic sealing apparatus 20a of the second embodiment in which two

such modules

20M and 20M mutually perform the forward operation may be achieved by, for example, being configured as follows. First, as shown in Fig. 10, the memory of the controller 80 has data relating to an operation pattern for the rear module 20M and data relating to an operation pattern for the front module 20M. The data for these operation patterns is completely identical without any phase offset of the rotational angle value between them. Also, the range of rotational angle values related to an ON state of the nipping instruction signal RON and the first rotational angle value specifying the initiation of generation of ultrasonic vibration are set to be the same for both the rear module 20M and the front module 20M.

Further, in the second embodiment, the two

modules

20M, 20M are included. Therefore, one cycle of the operation pattern corresponds to a range of the rotational angle value from 0^O to 720^O, the range being associated with the transport amount of two diapers. This enables the two

modules

20M, 20M to cooperate with each other and to form the welded section 14 at the product pitch P1 on the base material 1a of the diaper 1.

It is to be noted that, in the second embodiment, a case in which the number of modules 20M is two has been illustrated as an example, but, needless to say, three or more modules 20M may be arranged in a row.

Third Embodiment
Figs. 11A to 11J are diagrammatic views illustrating a third embodiment, and to be more specific, illustrating, in a series, that both the rear module 20M and the front module 20M of the third embodiment are forming welded sections 14 on the base material 1a. It is to be noted that in Figs. 11A-11J, the welded sections 14 formed by the rear module 20M are indicated with circles and the welded sections 14 formed by the front module 20M are indicated with triangles.

In the aforementioned second embodiment, as shown in Fig. 10, the two

modules

20M and 20M are performing a forward operation, which is identical to the reciprocating operation in the front-back direction, and the third embodiment differs in that a reverse operation is performed.

In other words, as shown in Figs. 11A-11J, the third embodiment is configured in such a manner that when the ultrasonic horn 30 and the anvil 60 associated with the rear module 20M (corresponds to the first module) move along the forward path in the front-back direction, the ultrasonic horn 30 and the anvil 60 associated with the front module 20M (corresponds to the second module) move along the backward path, and on the other hand, when the ultrasonic horn 30 and the anvil 60 associated with the rear module 20M move along the backward path in the front-back direction, the ultrasonic horn 30 and the anvil 60 associated with the front module 20M move along the forward path.

According to such a configuration, due to the reciprocating motion in the front-back direction of the ultrasonic horn 30 and the anvil 60, inertial forces exerted on the panel 19 supporting the rear module 20M and the front module 20M can be cancelled out, and as a result, mechanical vibration that may be produced in the panel 19 can be reduced.

It is to be noted that, for example, the ultrasonic sealing apparatus 20b related to the third embodiment in which the two

modules

20M and 20M mutually perform opposite operations can be achieved in a manner described below. Fig. 12 is an explanatory diagram of data relating to an operating pattern for each

module

20M and 20M.

First, in the memory of the controller 80, data relating to an operating pattern for a rear module 20M and data relating to an operating for a front module 20M, as shown in Fig. 12, are stored. Comparing the data for these operating patterns, the pattern shape is the same as each other, and phases of respective rotational angle values are offset by half a cycle, i.e., 360^O (one cycle, 720^O). Accordingly, the above-mentioned reverse operation is achieved.

Also, since the phase of the rotational angle value of the operation pattern of the front module 20M shown at the bottom of Fig. 12 is offset by half a cycle, i.e., 360^O with respect to the rear module 20M, the range of rotational angle value RON related to an ON state of the nipping instruction signal and the first rotational angle value specifying the initiation of generation of ultrasonic vibration for the front module 20M are also phase-shifted by half a cycle, i.e., 360^O from the range of rotational angle value RON of the rear module 20M and the first rotational angle value for the rear module 20M. Accordingly, also for the front module 20M, the welding process is performed in the equal speed region Re in the forward path.

Other embodiments
In the description above, the embodiments of the present invention have been mainly discussed, but the above-mentioned embodiments are provided for the purpose of facilitating the understanding of the present invention only and not intended for giving any limitation to the present invention. It goes without saying that any modifications and improvements to the present invention can be made without departing from the spirit of the invention and the present invention includes its equivalents. For example, variants described below are conceivable.

In the above-mentioned embodiment, a disposable diaper 1 that is worn on a wearing target and absorbs excretion fluid thereof was taken as an example of the absorbent article, but it is not limited thereto, as long as it absorbs excretion liquid such as urine and menstrual blood, and may be a sanitary napkin or a pet sheet which absorbs the excretion of a pet.

In the above-mentioned embodiments, the linear guides 40, 40AN and the ball screw mechanism 56, 56AN were illustrated as examples of the guiding members 40, 40AN and the front-back direction driving mechanism 50, 50AN that are related to the front-back direction reciprocating linear motion mechanism of the ultrasonic horn 30 and the anvil 60, but it is not limited thereto as long as the ultrasonic horn 30 and the anvil 60 are movable in a reciprocating manner along the linear transport track Tr1a of the base material 1a. For example, instead of the rails 42, 42AN of the linear guides 40, 40AN, sliders 44, 44AN may be slidably engaged with linear grooves (not shown) that are formed in the floor board 32 or the top board 62, or the rotational operation of the servo motors 52, 52AN may be converted into linear motion operation by using an appropriate cam mechanism instead of the ball screw mechanism 56, 56AN. It is to be noted that, in a case where the cam mechanism is used, since the above-mentioned operation pattern can be achieved by the setting of a cam curve of the cam, there may be a case where the data for the operation pattern stored in the memory of the controller 80 can be omitted. Also, a linkage between the driving rotational axis 52a, 52AN of the servo motors 52, 52AN and the screw shafts 57, 57AN is not limited to the coupling 55, 55AN, and for example, a linkage may achieved by using a wind-around transmission device including a timing belt and a pulley.

In the above-mentioned embodiments, the anvil 60 is located above the ultrasonic horn 30, but the up-down positional relationship can be opposite. In other words, the anvil unit 60U having the anvil 60 may be located below the ultrasonic horn unit 30U having the ultrasonic horn 30. However, from a maintenance point of view, rather than such a configuration, the first embodiment shown in Figs. 4A and 5 is more preferable. The reasons are as follows.

For example, in the case of the first embodiment, the ultrasonic horn 30 does not reciprocate in the up-down direction, but the anvil 60 reciprocates in the up-down direction, and many movable sections such as the air spring 74 are provided in association with the up-down motion, and consequently, these movable sections require maintenance. Here, according to the configuration of the first embodiment shown in Figs. 4A and 5A, in an operation halt state of the ultrasonic sealing apparatus 20, the anvil 60 is located above the base material 1a, and thus it is not in a state where it is covered with the base material 1a from the top like the ultrasonic horn 30 but rather substantially exposed in its entirety. Therefore, a maintenance person can carry out maintenance of the movable sections of the anvil 60 in a facilitated manner.

In the above-mentioned embodiment, the front-back direction transport track Tr1a of the base material 1a is horizontal, but it is not limited thereto, and may be inclined upwardly or downwardly at a predetermined angle of inclination against horizontal. However, in such a case, the linear track related to the front-back direction reciprocation of the ultrasonic horn 30 and the linear track related to the front-back direction reciprocation of the anvil 60 will be set at an inclination against horizontal with the same angle of inclination corresponding to the angle of inclination of the above-mentioned transport track Tr1a.

In the above-mentioned embodiment, as an example of the nipping drive mechanism, the ultrasonic horn 30 is configured to be immovable in the up-down direction and the anvil 60 is configured to be movable in the up-down direction, but it is not limited thereto. For example, it may be the anvil 60 that is configured to be immovable in the up-down direction or it may be the ultrasonic horn 30 that is configured to be movable in the up-down direction by the up-down direction reciprocation motion mechanism, and further, both the ultrasonic horn 30 and the anvil 60 may be configured in such a manner that each of them reciprocates in the up-down direction. It is noted that, it is preferable that one of the ultrasonic horn 30 and the anvil 60 is configured to be immovable in the up-down direction, since the number of movable sections for the nipping operation can be reduced.

In the above-mentioned embodiment, the air spring 74 is illustrated as an example of a drive source of the up-down direction reciprocating mechanism 70 serving as the nipping driving mechanism, but it is not limited thereto. For example, an air cylinder or hydraulic cylinder may be used, and the feed screw mechanism may be applied.

In the above-mentioned embodiment, the ceasing of the generation of ultrasonic vibration of the ultrasonic vibration generating apparatus 31 is performed by detecting, by the apparatus 31, that the amount of energy (Joules) of the applied ultrasonic vibration has reached the set value. However, depending on the case, after releasing the nipping of the base material 1a by the ultrasonic horn 30 and the anvil 60, the above-mentioned amount of energy may reach the set value, and in such a case, the welding will not be sufficient by an amount of ultrasonic vibration that was applied while not being nipped, and as a result, the strength of the welded section 14 may become insufficient. Therefore, it is preferable to configure as follows. First, the controller 80 receives a signal related to the ceasing of generation from the ultrasonic vibration generating apparatus 31 everytime the generation of ultrasonic vibration ceases. Then, the controller 80 compares a time of ceasing of generation that can be obtained from the signal and a time of releasing of the nipping, and in a case where the time of ceasing of generation is later than the time of release of the nipping, outputs an alarm for a bad welding to an appropriate alarm apparatus and informs the operator.

In the explanation of the above-mentioned embodiment, since the near-far relationship of the ultrasonic horn 30 and the anvil 60 with respect to the base material 1a in a case of the nipping release state illustrated in the enlarged side view of Fig. 5A has not been described in detail, this will be now be described. In this released state, the nipping surface 30a of the ultrasonic horn 30 is closer to the base material 1a than the nipping surface 60a of the anvil 60. According to such a positional relationship, a press-down amount when the anvil 60 descends to nip the base material 1a and presses the base material 1a against the ultrasonic horn 30 can be reduced. Accordingly, the irregularity of the transport track Tr1a for the base material 1a due to the pressing-in can be suppressed and, as a result, the welded section 14 can be formed in a more stable manner.

1 disposable diaper (absorbent article), 1a base material (continuous web), 1c position, 1e portion, 2 front sheet, 2a continuous web, 3 back sheet, 3a continuous web, 4 absorbent body, 5 elastic member, 6 elastic member, 8 waist opening section, 10 front section, 11 back section, 13 inseam section, 14 welded section, 19 panel, 19a vertical surface, 20 ultrasonic sealing apparatus, 20a ultrasonic sealing apparatus, 20b ultrasonic sealing apparatus, 20M rear module (first module), 20M front module (second module), 30 ultrasonic horn, 30U ultrasonic horn unit, 30a nipping surface, 31 ultrasonic vibration generating apparatus, 32 floor board, 40 linear guide (guiding member), 40AN linear guide (guiding member), 42 rail, 42AN rail, 44 slider, 44AN slider, 46 supporting table, 50 front-back driving mechanism, 50AN front-back driving mechanism, 52 servo motor, 52AN servo motor,
52a driving rotational axis, 52aAN driving rotational axis, 55 coupling, 55AN coupling, 56 ball screw mechanism (feed screw mechanism), 56AN ball screw mechanism (feed screw mechanism), 57 screw shaft, 57AN screw shaft, 58 nut member, 58AN nut member, 59 bearing member, 59AN bearing member, 60 anvil, 60U anvil unit, 60a nipping surface, 60d lower surface, 60f flange section, 60u upper surface, 61 rib, 61a protruded section, 62 top board, 70 up-down direction reciprocating mechanism (thickness direction reciprocating mechanism), 72 box member (anvil retaining section), 72d lower surface wall section, 72h through hole, 72u upper surface wall section, 72ud lower surface, 74 air spring, 76 supporting table, 80 controller, 90 transporting roller (transporting apparatus), Pb backward limit, Pf forward limit, Re equal speed region, RON region, Tr1a transport track (linear track)

Claims

An ultrasonic sealing apparatus that forms a plurality of welded sections at intervals along a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article, the apparatus comprising,
an ultrasonic horn that emits the ultrasonic vibration;
an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web; and
a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track,
the forward path having an equal speed region in which the ultrasonic horn and the anvil oppose each other in the thickness direction and move at a speed value which is the same as a transport speed value of the continuous web,
the ultrasonic horn and the anvil performing a nipping and a releasing of the nipping of the continuous web while moving in the equal speed region,
the ultrasonic horn emitting the ultrasonic vibration during the nipping of the continuous web.
The ultrasonic sealing apparatus according to claim 1, wherein
a plurality of modules are arranged along the linear track, each of the modules having the ultrasonic horn, the anvil and the reciprocating linear motion mechanism.
The ultrasonic sealing apparatus according to claim 2, wherein
the plurality of modules includes at least a first module and a second module,
a reciprocating linear motion mechanism of the second module carries out a motion in a backward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a forward path,
a reciprocating linear motion mechanism of the second module carries out a motion in a forward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a backward path.
The ultrasonic sealing apparatus according to claim 2, wherein
the plurality of modules includes at least a first module and a second module,
a reciprocating linear motion mechanism of the second module carries out a motion in a forward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a forward path,
a reciprocating linear motion mechanism of the second module carries out a motion in a backward path while a reciprocating linear motion mechanism of the first module is carrying out a motion in a backward path.
The ultrasonic sealing apparatus according to any one of claims 1 to 4, wherein,
during the nipping, the ultrasonic horn applies a pre-set amount of energy of the ultrasonic vibration to the continuous web.
The ultrasonic sealing apparatus according to any one of claims 1 to 5, further comprising a controller that controls the reciprocating linear motion mechanism, wherein,
under the control of the controller, the reciprocating linear motion mechanism repeatedly moves the ultrasonic horn and the anvil along the forward path and the backward path based on a predetermined operating pattern,
the controller has a plurality of data items relating to the operation pattern, the plurality of data items being different from each other,
the controller selects, from among the plurality of data items relating to the operating pattern, a data item relating to an operating pattern corresponding to a size of a formation pitch in the transport direction of the welded section to be formed, and uses the selected data item to control the reciprocating linear motion mechanism.
The ultrasonic sealing apparatus according to any one of claims 1 to 6, wherein
an up-down direction of the apparatus is orthogonal to the linear track, and the anvil is located above the ultrasonic horn in the up-down direction.
The ultrasonic sealing apparatus according to claim 7, wherein
the anvil is configured to be movable in the up-down direction, and the ultrasonic horn is configured to be immovable in the up-down direction.
The ultrasonic sealing apparatus according to claim 7, wherein
the anvil is configured to be immovable in the up-down direction, and the ultrasonic horn is configured to be movable in the up-down direction.
The ultrasonic sealing apparatus according to claim 7, wherein
both the anvil and the ultrasonic horn are configured to be movable in the up-down direction.
An ultrasonic sealing method that forms a plurality of welded sections at intervals in a transport direction of a continuous web by applying an ultrasonic vibration to the continuous web while the continuous web is being transported along a predetermined linear track, the continuous web being related to an absorbent article, the method comprising:
using
an ultrasonic horn that emits the ultrasonic vibration,
an anvil that cooperates with the ultrasonic horn so as to nip the continuous web in a thickness direction thereof while the ultrasonic horn is emitting the ultrasonic vibration towards the continuous web, and
a reciprocating linear motion mechanism that moves the ultrasonic horn and the anvil along a forward path and a backward path which are parallel to the linear track,
moving, in the forward path, the ultrasonic horn and the anvil at a speed value which is the same as the transport speed value of the continuous web with the ultrasonic horn and the anvil opposing each other in the thickness direction;
nipping the continuous web with the ultrasonic horn and the anvil, in the moving at the same speed;
releasing the nipping, in the moving at the same speed; and
emitting the ultrasonic vibration with the ultrasonic horn during the nipping.