Ultrasonic welding apparatus and method

Abstract

This ultrasound welding method comprises: a step for applying ultrasound energy to a workpiece; a step for reciprocally moving an anvil between an over-run region and a non-welding region; a step for guiding the anvil so that the anvil is in a first level in which the anvil is spaced apart from a surface level of a horn to prevent the anvil from abutting on the horn at an end portion far from a welding region, and causing the anvil to approach a second level in which the anvil contacts the horn in the welding region; and a step for performing control such that, in the over-run region, the anvil is displaced from the first level to the second level in a non-driven state in which the horn is not being caused to generate ultrasound energy, so that the anvil abuts on the horn without the workpiece therebetween.

Description

Technical Field

[0001] The present invention relates to an ultrasonic welding apparatus and method.

Background Art

[0002] An apparatus is known (Patent Document 1) that has an ultrasonic horn that rotates with a drum and an anvil that cooperates with the horn, and performs a welding process on a workpiece in which webs sandwiched between the horn and the anvil are stacked as the drum rotates and the anvil reciprocates in the axial direction of the drum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In this prior art, welding is performed during both the forward and backward movements of the anvil. However, due to misalignment of the web or the like during the forward and backward movements of the anvil, there are problems such as misalignment between the welding marks in the forward path and the welding marks in the return path, resulting in unstable welding strength or deterioration of the appearance.

[0005] It has been proposed to control such that the horn is vibrated via an ultrasonic generator to apply ultrasonic energy to the workpiece in either the forward or return path of the anvil, and ultrasonic energy is not applied to the workpiece in the other of the forward or return paths.

[0006] According to an example of this proposal, welding of the workpiece is performed only in one of the forward or return paths. Therefore, misalignment of the welding marks does not occur, and the welding strength does not become unstable or the appearance does not deteriorate.

[0007] In this case, within the range of motion of the anvil, in the region where a workpiece exists between the anvil and the horn, it is necessary to move the anvil closer to the horn in order to weld the workpiece. On the other hand, in the region of motion of the anvil where there is no workpiece between the anvil and the horn, it is necessary to move the anvil further away from the horn in order to suppress wear and deterioration of the anvil and the horn.

[0008] On the other hand, the sonic output from the horn is controlled to ensure a stable welding state and prevent horn deterioration. Therefore, a threshold is set for the sonic output, and an error message is generated if this threshold is exceeded.

[0009] However, as the anvil moves closer to the horn, from a first level where it is away from the horn to a second level where the horn makes contact with the anvil, an impact occurs on the horn when the anvil collides with it.

[0010] Such impacts can cause the sonic output to exceed the upper limit, resulting in an error message being displayed, the device shutting down, or deterioration of the horn.

[0011] Therefore, the object of the present invention is to provide an ultrasonic welding apparatus and method that can reduce the impact on the horn, prevent errors, and suppress the deterioration of the horn.

[0012] The present invention is an ultrasonic welding apparatus 1 that forms a welded portion S on a workpiece W such that a welded region α on the workpiece W extends in a first direction L1, and a non-welded region Δ extending to one side of the welded region α, where welding of the workpiece W is not required, is connected to the welded region α in the first direction L1. Horn 6 and Anvil 10, An ultrasonic generator 16 vibrates the horn 6 to impart ultrasonic energy to the workpiece W sandwiched between the anvil 10 and the horn 6, A moving mechanism moves the anvil 10 in the first direction L1 such that the horn 6 contacts the anvil 10 via the workpiece W in the welding region α and the non-welding region Δ, and moves the anvil 10 back and forth between the overrun region β that protrudes from the other side of the welding region α and the non-welding region Δ, A displacement mechanism that guides the anvil 10 so that it is at a first level away from the surface level of the horn 6, so that the anvil 10 does not come into contact with the horn 6 at the end (stroke end of the anvil) of the non-welding region Δ and the overrun region β that is far from the welding region α, and that allows the anvil 10 to approach a second level in which it comes into contact with the horn 6 in the welding region α, The device includes a control device 500 that controls the anvil 10 to displace from the first level to the second level in the overrun region β, when the horn 6 is in a non-driven state (including a weakly driven state) and no ultrasonic energy is being generated, so that the anvil 10 comes into contact with the horn 6 without the workpiece W being present.

[0013] The present invention is an ultrasonic welding method for forming a welded portion S on a workpiece W such that a welded region α on the workpiece W extends in a first direction L1, and a non-welded region Δ extending to one side of the welded region α, where welding of the workpiece W is not required, is connected to the welded region α in the first direction L1. A step of vibrating the horn 6 to apply ultrasonic energy to the workpiece W sandwiched between the anvil 10 and the horn 6, The process involves moving the anvil 10 in the first direction L1 so that the horn 6 contacts the anvil 10 via the workpiece W in the welding region α and the non-welding region Δ, and moving the anvil 10 back and forth between the overrun region β that protrudes from the other side of the welding region α and the non-welding region Δ, The process involves guiding the anvil 10 so that it is at a first level away from the surface level of the horn 6, so that the anvil 10 does not come into contact with the horn 6 at the ends (stroke ends of the anvil) of the non-welding region Δ and the overrun region β that are far from the welding region α, and then bringing the anvil 10 closer to a second level where it comes into contact with the horn 6 in the welding region α. The process includes controlling the anvil 10 to displace from a first level to a second level in the overrun region β while the horn 6 is in a non-driven state (including a weakly driven state) where ultrasonic energy is not generated, so that the anvil 10 comes into contact with the horn 6 without the workpiece W being involved.

[0014] In the present invention, "welding the workpiece" may refer to welding multiple overlapping webs together, or it may refer to welding a single web laminate folded in half, a so-called side seal. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a plan view and a cross-sectional view illustrating the general steps of the manufacturing method for disposable diapers according to the present invention. [Figure 2] Figure 2 is a front view of the main part of the ultrasonic welding apparatus according to the present invention. [Figure 3] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3. [Figure 5] Figure 5 is a view of the sheet holding drum shown in Figure 3 from the outside. [Figure 6] Figure 6 is a side view showing the horn, anvil, and lift cam. [Figure 7] Figure 7 is a cross-sectional view taken along line VII-VII in Figure 6. [Figure 8] Figure 8 is a side view showing the horn, anvil, and lift cam. [Figure 9]FIG. 9 is a schematic perspective view showing the operation in the forward path of the anvil. [Figure 10] FIG. 10 is a schematic perspective view showing the operation in the return path of the anvil. [Figure 11] FIG. 11 is a characteristic diagram showing the relationship between the movement of the anvil and the output of the horn.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and the drawings are for mere illustration and explanation and should not be used to define the scope of the present invention. The scope of the present invention is determined only by the claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.

[0017] Prior to the description of the apparatus according to an embodiment of the present invention, the structure and manufacturing method of a disposable diaper 20, which is an example of a wearing article manufactured by the apparatus, will be described.

[0018] Referring to FIG. 1, the disposable diaper 20 shown in (c) and (d) includes a front abdomen 20a disposed on the abdomen of the wearer, a rear back 20b disposed on the buttocks of the wearer, and a crotch part 20c extending from the front abdomen 20a through between the legs of the wearer to the rear back 20b when worn.

[0019] Both side edges of the front abdomen 20a and both side edges of the rear back 20b are welded to each other by two welding parts S so that the front abdomen 20a and the rear back 20b are connected in a circular shape.

[0020] Hereinafter, the manufacturing method of the disposable diaper 20 will be described.

[0021] In Figure 1(a), a workpiece W extending in the longitudinal direction is transported along its longitudinal direction. This workpiece W is processed to become a disposable diaper 20. Hereafter, the flow direction of the workpiece W will be referred to as the transverse direction, and the direction perpendicular to the transverse direction in Figure 1 will be referred to as the longitudinal direction.

[0022] Work W comprises a first stretchable sheet S1 that forms the front abdominal area 20a, a second stretchable sheet S2 that forms the back area 20b, and an absorbent material 200 that forms the crotch area 20c. Each sheet S1, S2 has an inner sheet that faces the skin side and is on the surface of the wearer's body when worn, an outer sheet that faces the non-skin side and is on the outside of the wearer when worn, and an elastic member F sandwiched between them.

[0023] The inner sheet is made of a liquid-permeable nonwoven fabric sheet and / or mesh sheet. The outer sheet is made of the same material as the inner sheet, or of polyethylene film, polypropylene film, or a water-repellent and breathable nonwoven fabric.

[0024] The elastic member F is constructed using a sheet or yarn made of polyurethane, natural rubber, or thermoplastic resin.

[0025] Workpiece W is positioned with its crotch area 20c positioned between its front abdomen 20a and rear back 20b. As workpiece W is transported, it is folded in half at the crotch area 20c.

[0026] The absorbent body 200 comprises a permeable sheet that is permeable to liquids, a water-repellent sheet that is water-repellent and breathable, and an absorbent core sandwiched between the permeable sheet and the water-repellent sheet.

[0027] Permeable sheets are composed of nonwoven fabric sheets and / or mesh sheets that are permeable to liquids. Water-repellent sheets are composed of polyethylene film, polypropylene film, or nonwoven fabric that is water-repellent and breathable.

[0028] The absorbent core is formed by laminating crushed pulp or a mixture of crushed pulp and a superabsorbent polymer.

[0029] By folding the workpiece W (continuous body) on which the absorbent material 200 is placed in half lengthwise, the portion corresponding to the front abdomen 20a and the portion corresponding to the back abdomen 20b of the workpiece W are overlapped. At this time, the lower edge of the back abdomen 20b protrudes downward from the front abdomen 20a. The protruding portion becomes a non-welded region Δ that will not be welded later.

[0030] In other words, the workpiece W in Figure 1 includes an anterior belly 20a and a posterior dorsal portion 20b, the posterior dorsal portion 20b covering the anterior belly 20a and having a non-welded region Δ that extends from the anterior belly 20a to one side in the first direction L1.

[0031] In the next welding process, the portion corresponding to the side edge of the front abdominal portion 20a and the portion corresponding to the side edge of the rear abdominal portion 20b of the folded workpiece W are ultrasonically welded together.

[0032] Specifically, in the welding process, two locations on the workpiece W are simultaneously ultrasonically welded, with an interval between them that separates the cutting range, which is predetermined to be cut in the cutting process described later, thereby forming a welded portion S on the workpiece W.

[0033] The welded portion S is formed in the longitudinal welded region α corresponding to the lateral edge of the anterior abdominal portion 20a and the lateral edge of the posterior dorsal portion 20b, respectively.

[0034] In the next cutting step, the workpiece W is cut along a virtual cutting line that extends vertically between the two welded sections S formed in the welding step. This separates the workpiece W (continuous body) into 20 disposable diapers.

[0035] The following describes an ultrasonic welding apparatus 1 according to one embodiment of the welding process, with reference to Figure 2.

[0036] The ultrasonic welding apparatus 1 includes an introduction roller 2 for introducing a workpiece W that has been folded in half in the folding process, a welding drum 3 for welding the workpiece W introduced by the introduction roller 2, and an exit roller 4 for leading out the workpiece W that has been welded by the welding drum 3.

[0037] The welding drum 3 comprises a sheet holding drum 5 that holds the workpiece W introduced by the introduction roller 2, six horns (ultrasonic horns) 6 provided on the sheet holding drum 5, six anvil units 7 that ultrasonically weld the workpiece W between each ultrasonic horn 6, a cylindrical anvil holding drum 8 (see Figure 3) that holds each anvil unit 7, a cam drum 9 (see Figure 3) provided inside the anvil holding drum 8, and six lift cams 18 (see Figure 3) fixed to the sheet holding drum 5 adjacent to each ultrasonic horn 6.

[0038] The welding drum 3 rotates and conveys the workpiece W along its outer surface, with the horn 6 and anvil 10 positioned so as to face each other radially on the inside and outside.

[0039] Referring to Figures 2 and 3, the sheet holding drum 5 is rotatable around the rotation center C1 while holding the workpiece W on its outer surface. The sheet holding drum 5 also has six grooves 5a formed at equal intervals around the rotation center C1. Each groove 5a opens outward from the sheet holding drum 5 and extends along the rotation center C1.

[0040] Each ultrasonic horn 6 applies ultrasonic vibrations to the workpiece W held in the sheet holding drum 5. Since each ultrasonic horn 6 has the same configuration as the others, only one ultrasonic horn 6 will be described, and the descriptions of the other ultrasonic horns 6 will be omitted.

[0041] Referring to Figure 7, the ultrasonic horn 6 comprises an input end 6a having an input surface 6c to which ultrasonic vibrations are input, and an output end 6b that branches in a direction perpendicular to the rotation center C1 (see Figure 2) by a slit 6d extending along the rotation center C1 of the sheet holding drum 5, and has a pair of output surfaces 6e that output ultrasonic vibrations on both sides of the slit 6d.

[0042] The width dimension of the slit 6d corresponds to the distance between the two welded sections S that are welded simultaneously during the welding process (see Figure 1).

[0043] The distance between the input surface 6c and each output surface 6e is set to a distance corresponding to half the wavelength (1 / 2λ) of the ultrasonic vibration input to the input surface 6c. The slit 6d is formed in the range from a position corresponding to a node (not shown) of the ultrasonic vibration input to the input surface 6c to the end face (output surface 6e) of the output end 6b.

[0044] The ultrasonic vibrations input to the ultrasonic horn 6 are longitudinal waves in a direction perpendicular to the output surface 6e.

[0045] Furthermore, as shown in Figures 2 and 5, the ultrasonic horn 6 is provided within the groove 5a such that each output surface 6e contacts the workpiece W held by the sheet holding drum 5 from the inside.

[0046] Here, as shown in Figure 5, the length of each output surface 6e is longer than the welding area α set on the workpiece W, and both ends of each output surface 6e in the longitudinal direction are positioned to protrude from the welding area α on both sides.

[0047] Each anvil unit 7 in Figure 3 is positioned at the same location as each ultrasonic horn 6 around the rotation center C1. Since each anvil unit 7 has the same configuration as the others, the configuration of one anvil unit 7 will be described, and the descriptions of the other anvil units 7 will be omitted.

[0048] The anvil unit 7 includes an anvil (roller) 10 for welding the workpiece W between itself and the ultrasonic horn 6, and an anvil holding member 11 that holds the anvil roller 10 so that the anvil roller 10 can move relative to the sheet holding drum 5 along the rotation center C1.

[0049] As shown in Figures 3 and 4, the holding member 11 includes a holding member body 12 that is movable along the rotation center C1 relative to the anvil holding drum 8, a holding lever 19 that is pivotably attached to the holding member body 12 around the pivot axis 19b in Figure 3 and holds the anvil roller 10 so as to be rotatable around the rotation axis 19a, and a biasing member 25 that biases the holding lever 19 in a direction that brings the anvil (roller) 10 closer to the ultrasonic horn 6.

[0050] In Figure 3, the rotation axis 19a and the oscillating axis 19b are axes that extend in directions perpendicular to the plane containing the rotation center C1 and the anvil unit 7 (directions perpendicular to the plane of paper in Figure 3), respectively. The rotation axis 19a is provided at the tip of the holding lever 19, and the oscillating axis 19b is provided in the middle of the holding lever 19.

[0051] Therefore, the anvil roller 10 can roll and make contact with the workpiece W in accordance with the movement of the holding member 11 along the rotation center C1, and can move closer to and away from the workpiece W (ultrasonic horn 6) in the radial direction of the sheet holding drum 5 in accordance with the rotation of the holding lever 19.

[0052] The biasing member 25 biases the anvil roller 10 toward the ultrasonic horn 6 by biasing the base end of the holding lever 19 toward the holding member body 12 toward the rotation center C1.

[0053] The biasing member 25, the holding lever 19, and the oscillating shaft 19b bias the anvil roller 10 toward the ultrasonic horn 6 so that the output surface 6e of the ultrasonic horn 6 and the welding surface 10d of the anvil roller 10 (described later) move closer to each other in the direction normal to these surfaces, and thus constitute a part of the displacement mechanism 100.

[0054] The holding member body 12 is provided with a cam projection 14 extending toward the rotation center C1, and a pair of engaging projections 15 shown in Figure 4 that protrude in opposite directions in directions perpendicular to the cam projection 14 and the rotation center C1 (left-right directions in Figure 4), and extend along the rotation center C1.

[0055] In Figure 4, the retaining member body 12 is provided between a pair of rails 17 erected on the outer circumferential surface of the anvil retaining drum 8. Each rail 17 has an engagement groove 17a that opens toward the other rail 17 and extends along the rotation center C1 (Figure 3). Each engagement projection 15 of the retaining member body 12 engages with the engagement groove 17a so that it can move along the rotation center C1 relative to the anvil retaining drum 8.

[0056] In Figure 3, the cylindrical anvil holding drum 8 is provided with a slit 16a that penetrates its peripheral wall and extends along the rotation center C1. The cam projection 14 of the holding member body 12 is inserted into the inside of the anvil holding drum 8 through the slit 16a.

[0057] Next, an example of the mobile mechanism 300 will be described. A cam drum 9 is provided inside the anvil holding drum 8, and a cam groove 9a is formed on the outer circumferential surface of this cam drum 9. The tip of the cam projection 14 is inserted into the cam groove 9a. The cam groove 9a guides the cam projection 14 so that the anvil unit 7 moves along the rotation center C1 in response to the rotation of the anvil holding drum 8 relative to the cam drum 9.

[0058] Here, the seat holding drum 5 and the anvil holding drum 8 are fixed to each other, and they rotate together around the rotation center C1. On the other hand, the rotational position of the cam drum 9 is fixed regardless of the rotation of the seat holding drum 5 and the anvil holding drum 8. Therefore, the holding member body 12 moves along the rotation center C1 in accordance with the rotation of the seat holding drum 5 and the anvil holding drum 8 around the rotation center C1.

[0059] Specifically, the anvil unit 7, located at the bottom in Figures 2 and 3, is positioned away from the workpiece W held by the sheet-holding drum 5 in a plan view. In this state, as the sheet-holding drum 5 rotates counterclockwise in Figure 2, the anvil unit 7 moves toward the workpiece W along the rotation center C1.

[0060] As the anvil unit 7 rotates to the uppermost position in Figures 2 and 3, the anvil roller 10 crosses the workpiece W, and in the uppermost position of the anvil unit 7 in Figures 2 and 3, the anvil roller 10 is positioned away from the workpiece W held by the sheet holding drum 5 in a plan view. If the sheet holding drum 5 rotates further counterclockwise from this state, the anvil roller 10 crosses the workpiece W again and returns to the position of the anvil roller 10 at the lowermost position in Figures 2 and 3.

[0061] In other words, in the ultrasonic welding apparatus 1, the anvil roller 10 reciprocates over the workpiece W in the welding region α of Figure 1 within the range E1 of Figure 2, and the workpiece W is welded during this reciprocating movement. More specifically, the anvil roller 10 located outside the range E1 of Figure 2 is located within the first and second overrun regions β and β2 of Figure 5, which are outside the workpiece W in a plan view. When the anvil roller 10 enters the range E1, it is located in the welding region α and non-welding region Δ that overlap the workpiece W in a plan view, and sequentially moves within the second overrun region β2, which is outside the workpiece W on the opposite side of the first overrun region β in a plan view, and within the welding region α and non-welding region Δ.

[0062] The lift cam 18 in Figure 6, which moves the anvil roller 10 located within the overrun regions β and β2 away from the workpiece W, will be explained below with reference to Figures 5 to 7.

[0063] The lift cam 18 in Figure 7 has a width dimension smaller than the width dimension of the slit 6d of the ultrasonic horn 6 and is a plate-shaped member provided within the width range of the slit 6d. Furthermore, the width dimension of the lift cam 18 is smaller than the distance between the pair of protrusions 10b of the anvil roller 10. Here, each protrusion 10b protrudes from the outer circumferential surface of the disc-shaped roller body 10a over its entire circumference and has a welding surface 10d that welds the workpiece W to the output surface 6e of the ultrasonic horn 6. The portion of the outer circumferential surface of the roller body 10a between the two protrusions 10b constitutes a supported surface 10c that can roll into contact with the lift cam 18, which will be described later.

[0064] The lift cam 18 in Figure 5 has a length greater than the length of the ultrasonic horn 6 and is positioned along the rotation center C1. For example, both longitudinal ends of the lift cam 18 are positioned outside the ultrasonic horn 6 and are fixed to the seat holding drum 5 (Figure 3) by a pair of bolts B1 in Figure 6.

[0065] The lift cam 18 in Figure 6 comprises a base-side guide portion 21 located within the non-contact area E4, a central portion 22 located within the contact area E3, and a tip-side guide portion 23 located within the non-contact area E2.

[0066] The central portion 22 has a non-guiding surface 22a that is located on the same plane as the output surface 6e of the ultrasonic horn 6 or at a position closer to the rotation center C1 than the output surface 6e.

[0067] The base end guide portion 21 has a base end guide surface 21a which includes an inclined surface that slopes radially outward from the non-guide surface 22a toward the center portion 22, and a flat surface that extends from the inclined surface toward the non-guide surface 22a (output surface 6e) toward the center portion 22.

[0068] Similarly, the tip-side guide portion 23 has a tip-side guide surface 23a which includes an inclined surface that slopes radially outward from the non-guide surface 22a toward the center portion 22, and a flat surface that extends from the inclined surface toward the non-guide surface 22a toward the center portion 22.

[0069] Each guide surface 21a, 23a is pressed against the supported surface 10c of the anvil roller 10 located within the first and second overrun regions β, β2 (Figure 5) by the biasing force of the biasing mechanism (biasing member 25, holding lever 19, and pivot shaft 19b). The lift cam 18 is fixed to the seat holding drum 5 with both guide surfaces 21a, 23a positioned within the widthwise range of the slit 16a (Figure 4).

[0070] In Figure 6, the two guide surfaces 21a and 23a roll and make contact with the supported surface 10c of the anvil roller 10 as the anvil roller 10 moves from the contact area E3 to the non-contact areas E2 and E4, thereby moving the anvil roller 10 located within the non-contact areas E2 and E4 away from the workpiece W (ultrasonic horn 6). Here, the supported surface 10c is the outer circumferential surface (outer surface) of the roller body 10a located between the protrusions 10b of the anvil roller 10.

[0071] In other words, the end of the base-side guide portion 21, including the base-side guide surface 21a, and the end of the tip-side guide portion 23, including the tip-side guide surface 23a, are inserted between the respective protrusions 10b of the anvil roller 10. As a result, the anvil roller 10 and the lift cam 18 located within the non-contact ranges E2 and E4 engage with each other in such a way that the movement of the anvil roller 10 is restricted in a direction perpendicular to the direction of movement of the anvil roller 10 and the direction of biasing by the biasing member 25 (the left-right direction in Figure 7).

[0072] The operation of the anvil roller 10 by the lift cam 18, which constitutes part of the displacement mechanism 100, will be described below.

[0073] In the process in which the anvil roller 10 in Figure 6 moves within the contact range E3, the welding surface 10d of the anvil roller 10 is pressed against the output surface 6e of the ultrasonic horn 6 with the workpiece W in between, due to the biasing force of the biasing member 25 (Figure 3).

[0074] In this pressed state, ultrasonic vibrations are applied to the ultrasonic horn 6, causing the workpiece W to be ultrasonically welded.

[0075] As the anvil roller 10 in Figure 6 begins to move from the contact area E3 towards the non-contact areas E2 and E4, the supported surface 10c of the anvil roller 10 comes into contact with the inclined surface of the guide surfaces 21a and 23a. As the anvil roller 10 continues to move, it rolls against the guide surfaces 21a and 23a (inclined surfaces) and gradually moves away from the ultrasonic horn 6 along the inclined surfaces, resisting the biasing force of the biasing member 25 (Figure 3). As the anvil roller 10 continues to move further, it comes into a state where it is supported by the flat surface of the guide surfaces 21a and 23a. In other words, both guide surfaces 21a and 23a have a shape that allows the anvil roller 10 to be guided in a direction in which the output surface 6e and the welding surface 10d move away from each other in the direction normal to each other, resisting the biasing force of the biasing member 25.

[0076] In this supported state, the welding surface 10d of the anvil roller 10 is set back from the output surface 6e of the ultrasonic horn 6 by a predetermined distance (a distance greater than the amplitude of the ultrasonic vibration). Therefore, wear and deterioration of the ultrasonic horn 6 and the anvil roller 10 caused by the ultrasonic vibration applied to the ultrasonic horn 6 being transmitted to the anvil roller 10 can be prevented.

[0077] Meanwhile, as the anvil roller 10 begins to move from the non-contact areas E2 and E4 towards the contact area E3, the anvil roller 10 rolls and makes contact with the guide surfaces 21a and 23a, and gradually approaches the ultrasonic horn 6 along the inclined surface due to the biasing force of the biasing member 25 (Figure 3). As the anvil roller 10 continues to move, it reaches the contact area E3.

[0078] In other words, the biasing mechanism (biasing member 25, holding lever 19, and pivot shaft 19b) and the lift cam 18 correspond to a displacement mechanism 100 that displaces the anvil roller 10 relative to the ultrasonic horn 6 such that the output surface 6e and the welding surface 10d move closer to each other in the contact range E3, and the output surface 6e and the welding surface 10d move further apart in the non-contact ranges E2 and E4.

[0079] As described above, the anvil roller 10 is biased toward the ultrasonic horn 6, and this biasing force causes the outer surface of the anvil roller 10, located within the non-contact ranges E2 and E4, to press against the guide surfaces 21a and 23a of the lift cam 18.

[0080] Furthermore, the two guide surfaces 21a and 23a guide the anvil roller 10 in a direction that moves the output surface 6e and the welding surface 10d away from each other as the anvil roller 10 moves from the contact area E3 to the non-contact areas E2 and E4.

[0081] Therefore, when the anvil roller 10 is in contact range E3, the biasing force of the biasing member 25 (Figure 3) brings the output surface 6e and the welding surface 10d closer together in the direction normal to these surfaces, allowing the workpiece W to be ultrasonically welded between them. On the other hand, as the anvil roller 10 moves from contact range E3 to non-contact ranges E2 and E4, the anvil roller 10 is guided along the guide surfaces 21a and 23a, thereby moving the output surface 6e and the welding surface 10d further apart from each other.

[0082] Next, we will explain the details of the ultrasonic welding apparatus 1. The ultrasonic welding apparatus 1 forms a welded portion S on the workpiece W such that the welded region α, to which the workpiece W is welded in Figure 1(c), extends in a first direction L1, and a non-welded region Δ, which extends to one side of the welded region α and does not need to be welded to the workpiece W, is connected to the welded region α in the first direction L1. In this example, the first direction L1 is the width direction perpendicular to the waist circumference direction of the wearable item 20.

[0083] The ultrasonic welding apparatus 1 shown in Figure 8(a) comprises an ultrasonic generator 16 and a control device 500. The ultrasonic generator 16 vibrates a horn 6 to impart ultrasonic energy to the workpiece W sandwiched between the anvil 10 and the horn 6.

[0084] As shown in Figures 8(a) and 8(b), the moving mechanism 300 moves the anvil 10 in a first direction L1 so that the horn 6 contacts the anvil 10 via the workpiece W in the welding region α and the non-welding region Δ, and also moves the anvil 10 back and forth between the first overrun region β that protrudes from the other side of the welding region α, the non-welding region Δ, and the second overrun region β2.

[0085] The displacement mechanism 100 includes a lift cam 18 that guides the anvil 10 so that it reaches a first level, and the biasing member 25 (Figure 3) that biases the anvil 10 so that it contacts the horn 6.

[0086] The lift cam 18 of the displacement mechanism 100 guides the anvil 10 so that it reaches a distal first level away from the surface level of the horn 6, so that the anvil 10 does not come into contact with the horn 6 at the end (stroke end of the anvil) far from the welding region α in the non-welding region Δ and the second overrun region β2, while allowing the anvil 10 to approach a proximal second level where it contacts the horn 6 in the welding region α. ​​The lift cam 18 may be divided into two in the first direction L1.

[0087] In the forward path OB shown in Figure 8(a), the control device 500 controls the anvil 10 to displace from the first level to the second level in the first overrun region β when the horn 6 is in a non-driven state (including a weakly driven state) and no ultrasonic energy is being generated, so that the anvil 10 comes into contact with the horn 6 without the workpiece W being involved.

[0088] In the return path IB shown in Figure 8(b), the control device 500 controls the anvil 10 to displace from the first level to the second level so that it comes into contact with the horn 6 via the workpiece W, while the horn 6 is in a driving state where ultrasonic energy is being generated in the non-welding region Δ.

[0089] The control device 500 controls the anvil 10 in Figure 9 to apply ultrasonic energy to the workpiece W only in the return path IB of the forward path OB, which moves from one side to the other in the first direction L1, and in the return path IB, which moves from one side to the other in Figure 10.

[0090] As shown in Figure 8(b), the anvil 10 of the return path IB is displaced from the first level to the second level in the non-welding region Δ, and the welding drum 3 transports the workpiece W so that the anvil 10 comes into contact with the horn 6 via the workpiece W in the non-welding region Δ. That is, the workpiece W is positioned eccentrically towards the second overrun region β2 by the amount of the non-welding region Δ with respect to the center of the horn 6.

[0091] Therefore, in the return path IB, the anvil (roller) 10 collides with (comes into) the horn 6 during operation via the non-welded region Δ of the workpiece W from the second overrun region β2, and does not directly collide with the horn 6.

[0092] As shown in Figure 11(b), the control device 500 has an output unit 501 that takes the sonic output of the horn 6 as input and outputs an error when the sonic output reaches a predetermined threshold.

[0093] Next, the operation of the ultrasonic welding apparatus 1, including the method for forming the welded portion S shown in Figure 10, will be described.

[0094] In this example, as shown in Figure 1(c), welded portions S are formed at both ends of the waist portion of the wearable item 20. As shown in Figure 1(a), the welded portions S are formed near the cutting lines of adjacent wearable items 20. As shown in Figure 10, the welded portions S are formed intermittently in the first direction L1 within the welded region α.

[0095] In this welding method, the control device 500 controls the anvil 10 in Figure 9 to apply ultrasonic energy to the workpiece W only in the return path IB of the forward path OB, which moves from one side to the other in the first direction L1, and in the return path IB, which moves from one side to the other in Figure 10.

[0096] First, let's explain the outbound OB in Figure 8(a). In this figure, the anvil 10 is held at the distal first level by the lift cam 18 at the origin position shown by the solid line. As the anvil 10 moves in the first direction L1 from the origin position (first overrun region β), it displaces from the first level to the proximal second level along the inclined surface of the lift cam 18 and comes into contact with the surface of the horn 6 (output surface 6e).

[0097] After this contact, the anvil 10 crosses the welded area α and non-welded area Δ of the workpiece W, rises again to the first level along the inclined surface of the lift cam 18, and advances to the stroke end (second overrun area β2) indicated by the dashed line.

[0098] In the forward path OB described above, the horn 6 does not vibrate substantially. Therefore, as shown in Figure 9, the workpiece W is not welded in the forward path OB.

[0099] Next, we will explain the return leg IB in Figure 10. In this return path IB, the anvil 10 returns from the stroke end (second overrun region β2), indicated by the dashed line, to the origin position (first overrun region β), indicated by the solid line. As shown in Figure 8(b), at the stroke end (second overrun region β2), the anvil 10 is held at a first level by the lift cam 18, not in contact with the horn 6.

[0100] In the return stroke IB shown in Figure 8(b), the anvil 10 moves from the stroke end toward the opposite side of the first direction L1, displacing from the distal first level to the proximal second level along the inclined surface of the lift cam 18, and contacting the surface of the horn 6 (output surface 6e) via the workpiece W in the non-welding region Δ. In this return stroke IB, the horn 6 undergoes intermittent ultrasonic welding. However, because the thickness of the workpiece W is thin in the non-welding region Δ, no welding energy is generated in the workpiece W.

[0101] During the contact in the return path IB, the horn output shown in Figure 11(b) becomes larger than during welding due to the added energy from the collision. However, since the anvil 10 does not directly contact (metal contact) the horn 6, but rather contacts the horn 6 via the non-welded region Δ of the workpiece W, the collision energy does not become very large, and therefore the horn output becomes smaller than a predetermined threshold. For this reason, there is no risk of the control device 500 outputting an error.

[0102] In Figure 11(b), the anvil 10, shown by the solid line, passes through the non-welding region Δ and then through the welding region α. ​​During this time, the horn 6 vibrates ultrasonically, sandwiching the welding region α of the workpiece W between itself and the anvil 10, and applying ultrasonic energy to the workpiece W between the anvil 10 and the horn 6. As a result, numerous welded parts S are formed in two rows in the welding region α, as shown in gray in Figure 10.

[0103] As shown in Figure 11(b), during this welding process, the output of the horn due to ultrasonic vibration appears as a waveform. The level of this output is lower than the output level in the non-welding region Δ mentioned above.

[0104] In Figure 11(b), the anvil 10, having passed through the aforementioned welding region α, moves toward the origin position indicated by the dashed line. At this time, the anvil 10 passes through a first overrun region β on the surface of the horn 6 where no workpiece W is placed. In this first overrun region β, the horn 6 repeatedly vibrates ultrasonically and directly collides with (metal contact with) the anvil 10. Therefore, the horn output becomes greater than during the welding described above.

[0105] However, this horn output is set to be smaller than a predetermined threshold. Therefore, there is no risk of an error output being generated.

[0106] Subsequently, the anvil 10 rises again along the inclined surface of the lift cam 18 to the first level and returns to the origin position shown by the dashed line.

[0107] Thus, in this example shown in Figure 11(b), the impact of a large drop collision T1 and the metal contact T3 occur separately before and after the welding T2, so that the impact of the large drop collision T1 and the metal contact T3 do not overlap. Therefore, it is possible to prevent the horn output from becoming excessively large and to prevent the occurrence of error output.

[0108] To make the effects of this example easier to understand, we will explain the case where T1 during a fall impact and T3 during metal contact occur simultaneously using Figure 11(a).

[0109] Figure 11(a) shows a reference example not included in the present invention. As shown in this figure, when the first level anvil 10, indicated by the solid line, descends the inclined surface of the lift cam 18 and directly contacts (metal contacts) the horn 6, the impact from the falling collision of the anvil 10 overlaps with the impact from the metal contact. Furthermore, the horn 6 is vibrating ultrasonically, and the impact energy from this vibration with the anvil 10 also overlaps. Therefore, as shown in this figure, the horn output becomes significantly larger than during welding (T2), making it easier to exceed a predetermined threshold. Note that T4 is the non-welding stage, but because the workpiece W is thin, the horn output is higher than during welding (T2).

[0110] In contrast, in the example shown in Figure 11(b), it is possible to prevent the horn output from becoming excessively large and to prevent the occurrence of error output.

[0111] The above specific embodiments include the invention of an ultrasonic welding apparatus having the following configuration.

[0112] The present invention is an ultrasonic welding apparatus 1 that forms a welded portion S on a workpiece W such that a welded region α on the workpiece W extends in a first direction L1, and a non-welded region Δ extending to one side of the welded region α, where welding of the workpiece W is not required, is connected to the welded region α in the first direction L1. A horn 6 and an anvil 10, and an ultrasonic generator 16 that vibrates the horn 6 to impart ultrasonic energy to the workpiece W sandwiched between the anvil 10 and the horn 6, A moving mechanism 300 moves the anvil 10 in the first direction L1 so that the horn 6 contacts the anvil 10 via the workpiece W in the welding region α and the non-welding region Δ, and moves the anvil 10 back and forth between the overrun region β that protrudes from the other side of the welding region α and the non-welding region Δ, A displacement mechanism 100 guides the anvil 10 so that it is at a first level away from the surface level of the horn 6, so that the anvil 10 does not come into contact with the horn 6 at the end (stroke end of the anvil) of the non-welding region Δ and the overrun region β that is far from the welding region α, and allows the anvil 10 to approach a second level in which it comes into contact with the horn 6 in the welding region α. The device includes a control device 500 that controls the anvil 10 to displace from the first level to the second level in the overrun region β, when the horn 6 is in a non-driven state (including a weakly driven state) and no ultrasonic energy is being generated, so that the anvil 10 comes into contact with the horn 6 without the workpiece W being present.

[0113] According to the apparatus of the present invention, in the overrun region β, the anvil 10 is displaced from a first level to a second level relative to the non-driven horn 6, and the anvil 10 comes into contact with the horn 6 without the workpiece W being involved. Therefore, although an impact occurs due to the contact, no energy is added due to ultrasonic vibration. As a result, excessive impact can be suppressed, and deterioration of the horn can be suppressed.

[0114] Preferably, in the non-welding region Δ, the control device 500 controls the anvil 10 to be displaced from the first level to the second level while the horn 6 is in a driving state where ultrasonic energy is being generated, so that the anvil 10 comes into contact with the horn 6 via the workpiece W.

[0115] In this case, although the horn 6 is in a driven state in the non-welded region Δ, and therefore vibration-induced shock occurs to the horn 6, metal-to-metal contact can be prevented because the horn 6 contacts the anvil 10 via the non-welded region Δ of the workpiece W. Consequently, the shock generated to the horn is reduced.

[0116] In a preferred example, the displacement mechanism 100 may include a lift cam 18 that guides the anvil 10 to the first level, and a biasing member 25 that biases the anvil 10 so that it contacts the horn 6.

[0117] In a preferred example, the welding drum 3 may be provided, which rotates while conveying the workpiece W along its outer surface, and the horn 6 and anvil 10 are arranged to face each other radially on the inside and outside.

[0118] More preferably, the workpiece W includes a front abdominal portion 20a and a back portion 20b of the wearable article 20, wherein the back portion 20b covers the front abdominal portion 20a and has the non-welded region Δ that extends from the front abdominal portion 20a to one side in the first direction L1. The control device 500 controls the anvil 10 to apply ultrasonic energy to the workpiece W only in the return path IB of the forward path OB, which moves from the other side of the first direction L1 to the one side, and the return path IB, which moves from the one side to the other side.

[0119] In this case, ultrasonic welding of the workpiece W is performed only on the return path IB during the round trip movement. Therefore, a weld with stable welding strength and excellent appearance is obtained.

[0120] More preferably, the anvil 10 is displaced from the first level to the second level in the non-welding region Δ, and the welding drum 3 conveys the workpiece W such that the anvil 10 comes into contact with the horn 6 via the workpiece W in the non-welding region Δ.

[0121] As the welding drum 3 transports the workpiece W in this manner, when the anvil 10 is displaced from the first level to the second level, the anvil 10 comes into contact with the horn 6 via the non-welded region Δ of the workpiece W, and the impact of the collision due to the fall is mitigated by the non-welded region Δ of the workpiece W.

[0122] More preferably, the control device 500 has an output unit 501 that receives the sonic output of the horn 6 as input and outputs an error when the sonic output reaches a predetermined threshold.

[0123] In this case, when the sonic output becomes excessive, the control unit 500 and the operator can detect this, thus preventing horn degradation.

[0124] On the other hand, the aforementioned specific embodiments include an invention of an ultrasonic welding method having the following steps. The present invention is an ultrasonic welding method for forming a welded portion S on a workpiece W such that a welded region α, to which the workpiece W is welded, extends in a first direction L1, and a non-welded region Δ, which extends to one side of the welded region α and does not need to be welded to the workpiece W, is connected to the welded region α in the first direction L1. A step of vibrating the horn 6 to apply ultrasonic energy to the workpiece W sandwiched between the anvil 10 and the horn 6, The process involves moving the anvil 10 in the first direction L1 so that the horn 6 contacts the anvil 10 via the workpiece W in the welding region α and the non-welding region Δ, and moving the anvil 10 back and forth between the overrun region β that protrudes from the other side of the welding region α and the non-welding region Δ, The process involves guiding the anvil 10 so that it is at a first level away from the surface level of the horn 6, so that the anvil 10 does not come into contact with the horn 6 at the ends of the non-welded region Δ and the overrun region β that are far from the welding region α, and then bringing the anvil 10 closer to a second level where it comes into contact with the horn 6 in the welding region α. In the overrun region β, the anvil 10 is displaced from the first level to the second level in a non-driven state where ultrasonic energy is not generated in the horn 6, and is controlled to come into contact with the horn 6 without the workpiece W being involved.

[0125] According to the method of the present invention, in the overrun region β, the anvil 10 is displaced from a first level to a second level relative to the non-driven horn 6, and the anvil 10 comes into contact with the horn 6 without the workpiece W being involved. Therefore, although an impact occurs due to the contact, no energy is added due to ultrasonic vibration. As a result, excessive impact can be suppressed, and deterioration of the horn can be suppressed.

[0126] Preferably, in the non-welding region Δ, while the horn 6 is in a driving state where ultrasonic energy is being generated, the anvil 10 is controlled to be displaced from the first level to the second level so that the anvil 10 comes into contact with the horn 6 via the workpiece W.

[0127] In this case, although the horn 6 is in a driven state in the non-welded region Δ, and therefore vibration-induced shock occurs to the horn 6, metal-to-metal contact can be prevented because the horn 6 contacts the anvil 10 via the non-welded region Δ of the workpiece W. Consequently, the shock generated to the horn is reduced.

[0128] More preferably, the workpiece W includes a front abdominal portion 20a and a back portion 20b of the wearable article 20, wherein the back portion 20b covers the front abdominal portion 20a and has the non-welded region Δ that extends from the front abdominal portion 20a to one side in the first direction L1. The control device 500 controls the anvil 10 to apply ultrasonic energy to the workpiece W only in the return path IB of the forward path OB, which moves from the other side of the first direction L1 to the one side, and the return path IB, which moves from the one side to the other side.

[0129] In this case, ultrasonic welding of the workpiece W is performed only on the return path IB during the round trip movement. Therefore, a weld with stable welding strength and excellent appearance is obtained.

[0130] More preferably, the system further includes a step of taking the sonic output of the horn 6 as input and outputting an error when the sonic output reaches a predetermined threshold.

[0131] As the welding drum 3 transports the workpiece W in this manner, when the anvil 10 is displaced from the first level to the second level, the anvil 10 comes into contact with the horn 6 via the non-welded region Δ of the workpiece W, and the impact of the collision due to the fall is mitigated by the non-welded region Δ of the workpiece W.

[0132] Features described and / or illustrated in relation to each of the embodiments described above may be used in the same or similar form, and / or in combination with or instead of features of other embodiments, in one or more other embodiments.

[0133] As described above, preferred embodiments have been explained with reference to the drawings, but those skilled in the art will readily anticipate various changes and modifications within the obvious scope by reviewing this specification. For example, the anvil may be positioned radially inward on the outer surface of the web support member, and the horn may be positioned outside the same outer surface. Furthermore, a structure similar to US2017 / 0027762 A1 may be adopted as the moving mechanism. Additionally, the drum may have only one set of horns and anvils, or multiple sets. Furthermore, parts of the pant-type garment other than the so-called side seals may be welded. Therefore, such changes and modifications shall be construed as falling within the scope of the invention as defined by the claims. [Industrial applicability]

[0134] This invention can be used in production equipment for disposable wearable items such as disposable pants, diapers, and sanitary products, as well as in production equipment for medical wound dressings and the like. [Explanation of Symbols]

[0135] 1: Ultrasonic welding device 2: Inlet roller 3: Welding drum 4: Outlet roller 5: Sheet holding drum (holding member) 5a: Groove 6: (Ultrasonic) Horn 6a: Input end 6b: Output end 6c: Input side 6d: Slit 6e: Output side 7: Anvil unit 8: Anvil holding drum 9: Cam drum 9a: Cam groove 10: Anvil (roller) 10a: Roller body 10b: Protruding part 10c: Supported surface 10d: Welding surface 11: Retaining member 12: Main body of the retaining member 14: Cam projection 15: Engaging projection 16: Ultrasonic generator 16a: Slit 17: Rail 17a: Engagement groove 18: Lift cam 19: Holding lever 19a: Rotation axis 19b: Oscillating axis 20: Items worn (disposable diapers) 20a: Front abdomen 20b: Back 20c: Crotch area 200: Absorbent material 21: Base end guide portion 21a: Base end guide surface 22: Central part 22a: Non-guiding surface 23: Tip side guide section 23a: Tip side guide surface 25: Biasing member 500: Control device 501: Output unit 100: Displacement mechanism 300: Moving mechanism E1: Range E2, E4: Non-contact range E3: Contact range F: Elastic member S: Welded part S1(S2): First (second) stretchable sheet IB: Return journey OB: Outbound journey L1: First direction T1: During impact from falling T2: During welding T3: During metal contact α: Welding area β: Overrun area Δ: Non-welding area

Claims

1. An ultrasonic welding apparatus (1) that forms a welded portion (S) on a workpiece (W) such that a welded region (α) to which the workpiece (W) is welded extends in a first direction (L1), and a non-welded region (Δ) extending to one side of the welded region (α) and not requiring welding of the workpiece (W) is connected to the welded region (α) in the first direction (L1), Horns (6) and anvils (10), An ultrasonic generator (16) vibrates the horn (6) to impart ultrasonic energy to the workpiece (W) sandwiched between the anvil (10) and the horn (6), A moving mechanism (300) moves the anvil (10) in the first direction (L1) such that the horn (6) contacts the anvil (10) via the workpiece (W) in the welding region (α) and the non-welding region (Δ), and moves the anvil (10) back and forth between the overrun region (β) that protrudes from the other side of the welding region (α) and the non-welding region (Δ), A displacement mechanism (100) guides the anvil (10) so that it is at a first level away from the surface level of the horn (6) so that the anvil (10) does not come into contact with the horn (6) at the ends of the non-welded region (Δ) and the overrun region (β) that are far from the welded region (α), and allows the anvil (10) to approach a second level in which it comes into contact with the horn (6) in the welded region (α). The control device (500) controls the anvil (10) to displace from the first level to the second level in the overrun region (β) in a non-driven state where ultrasonic energy is not generated in the horn (6), so that the anvil (10) comes into contact with the horn (6) without the workpiece (W) in between. In the non-welding region (Δ), the control device (500) controls the anvil (10) to displace from the first level to the second level while the horn (6) is in a driving state in which ultrasonic energy is generated, so that the anvil (10) comes into contact with the horn (6) via the workpiece (W). Ultrasonic welding device (1).

2. In claim 1, The displacement mechanism (100) comprises a lift cam (18) that guides the anvil (10) to the first level, and a biasing member (25) that biases the anvil (10) so that it contacts the horn (6), in an ultrasonic welding apparatus (1).

3. In claim 2, An ultrasonic welding apparatus (1) is provided with a welding drum (3) that rotates and transports the workpiece (W) along its outer surface, and has the horn (6) and anvil (10) positioned to face each other radially on the inside and outside.

4. In claim 3, The workpiece (W) includes the front abdominal portion (20a) and the back portion (20b) of the wearable article (20), the back portion (20b) covers the front abdominal portion (20a) and has the non-welded region (Δ) that protrudes from the front abdominal portion (20a) to one side in the first direction (L1), The control device (500) controls the anvil (10) to apply ultrasonic energy to the workpiece (W) only during the return path (IB) of the forward path (OB) in which the anvil (10) moves from the other side in the first direction (L1) to the one side, and the return path (IB) in which it moves from the one side to the other side. Ultrasonic welding device (1).

5. In claim 4, An ultrasonic welding apparatus (1), wherein the anvil (10) is displaced from the first level to the second level in the non-welding region (Δ), and the welding drum (3) transports the workpiece (W) such that the anvil (10) comes into contact with the horn (6) via the workpiece (W) in the non-welding region (Δ).

6. In claim 5, The control device (500) has an output unit 501 that takes the sonic output of the horn (6) as input and outputs an error when the sonic output reaches a predetermined threshold, and is an ultrasonic welding apparatus (1).

7. An ultrasonic welding method for forming a welded portion (S) on a workpiece (W) such that a welded region (α) to which the workpiece (W) is welded extends in a first direction (L1), and a non-welded region (Δ) extending to one side of the welded region (α) and not requiring welding of the workpiece (W) is connected to the welded region (α) in the first direction (L1), wherein A step of vibrating the horn (6) to apply ultrasonic energy to the workpiece (W) sandwiched between the anvil (10) and the horn (6), The process involves moving the anvil (10) in the first direction (L1) such that the horn (6) contacts the anvil (10) via the workpiece (W) in the welding region (α) and the non-welding region (Δ), and moving the anvil (10) back and forth between the overrun region (β) that protrudes from the other side of the welding region (α) and the non-welding region (Δ), A step of guiding the anvil (10) so that it is at a first level away from the surface level of the horn (6) so that the anvil (10) does not come into contact with the horn (6) at the ends of the non-welded region (Δ) and the overrun region (β) that are far from the welded region (α), and bringing the anvil (10) closer to a second level in which it comes into contact with the horn (6) in the welded region (α), The process includes controlling the anvil (10) to displace from the first level to the second level in the overrun region (β) while the horn (6) is not being driven and ultrasonic energy is not being generated, so that the anvil (10) comes into contact with the horn (6) without the workpiece (W) in between. In the non-welding region (Δ), while the horn (6) is in a driving state where ultrasonic energy is being generated, the anvil (10) is controlled to be displaced from the first level to the second level so that the anvil (10) comes into contact with the horn (6) via the workpiece (W). Ultrasonic welding method.

8. In claim 7, The workpiece (W) includes the front abdominal portion (20a) and the back portion (20b) of the wearable article (20), the back portion (20b) covers the front abdominal portion (20a) and has the non-welded region (Δ) that protrudes from the front abdominal portion (20a) to one side in the first direction (L1), The anvil (10) is controlled to apply ultrasonic energy to the workpiece (W) only during the return path (IB) of the forward path (OB) from the other side in the first direction (L1) to the one side, and the return path (IB) from the one side to the other side. Ultrasonic welding method.

9. In claim 8, An ultrasonic welding method further comprising the step of taking the sonic output of the horn (6) as input and outputting an error when the sonic output reaches a predetermined threshold.

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