Ultrasonic joint method and ultrasonic joint structure

Abstract

To provide a joint method etc. which can achieve improvement of sealing strength by a lid member for a through hole of a housing etc.SOLUTION: A first workpiece W1 and a second workpiece W2 are joined so as to close a through hole W20 provided at the second workpiece W2 by a sealing portion included in the first workpiece W1 and formed in a disk-like, columnar, or inverted truncated cone shape. The through hole W20 is formed so that a portion from an opening to an annular step portion W22 in a middle part fits in a shape of the sealing portion of the first workpiece W1. A horn tip 140 (an ultrasonic junction chip) is placed in contact with an upper surface of the first workpiece W1 in a state that the sealing portion is inserted into the through hole W20 of the second workpiece W2. Ultrasonic complex vibrations are caused so that the horn chip 140 has ultrasonic vibration components in two vertical directions on a plane parallel to the upper surface of the first workpiece W1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic joining technique for joining a plurality of workpieces made of various materials such as metals by using ultrasonic vibrations. [Background technology]

[0002] Conventionally, as shown in FIG. 8, a metal cover member 51 is used to close a through-hole 520 (e.g., an electrolyte injection port) provided in a metal housing 52 (e.g., a wall material of a battery housing). The cover member 51 has a substantially cylindrical main body portion 511 and a substantially annular flange portion 512 that protrudes radially from the entire periphery of the upper portion of the main body portion 511. The through-hole 520 in the housing 52 has a shape in which three substantially cylindrical spaces of different diameters are stacked coaxially so that the diameter decreases in two stages from the top. The housing 52 is formed with a substantially annular first step portion 522 and a second step portion 524 as the two diameter-reducing portions of the through-hole 520.

[0003] 8, cover member 51 is inserted into through-hole 520 of housing 52, and the side surface of flange portion 512 abuts against inner surface 521 that defines the maximum diameter portion of through-hole 520, and the lower surface of flange portion 512 abuts against first step portion 522 of housing 52. In this state, laser light LB is irradiated along the outer surface of flange portion 512 of cover member 51 in a circular trajectory. As a result, the outer surface of flange portion 512 of cover member 51 and inner surface 521 of the maximum diameter portion of through-hole 520 of housing 52 are welded together over the entire circumference, and through-hole 520 of housing 52 is closed by cover member 51 (see, for example, Patent Document 1).

[0004] However, residual stress exists between the laser-welded lid member 51 and the housing 52, which may reduce the sealing strength of the lid member 51 at the through-hole 520 in the housing 52, and thus the pressure resistance of the housing 52. Furthermore, the electrolyte adhering to the injection port is likely to form pinholes during laser welding, which may reduce the sealing strength of the lid member 51 at the through-hole 520 in the housing 52, and therefore the pressure resistance of the housing 52.

[0005] Therefore, as shown in FIG. 9, a technology has been proposed in which the through-hole 620 in the housing 62 is sealed by ultrasonically joining the lower peripheral portion 612 of a substantially disk-shaped or cylindrical cover member 61 all around to the tapered side wall 622 of the substantially circular mortar-shaped through-hole 620 provided in the housing 62 (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-219962 [Patent Document 2] Japanese Patent Application Publication No. 2023-182089 Summary of the Invention [Problem to be solved by the invention]

[0007] However, since the bonding area of the lid member 61 to the housing 62 is small, the sealing strength of the lid member 61 at the through-hole 620 of the housing 62, and therefore the pressure resistance strength of the housing 62, may decrease.

[0008] Therefore, an object of the present invention is to provide a joining method and the like that can further improve the sealing strength of a cover member for a through hole in a housing or the like. [Means for solving the problem]

[0009] The ultrasonic bonding method of the present invention comprises the steps of: A method for joining a first workpiece and a second workpiece such that a sealing portion of a first workpiece formed in a disk, column, or inverted truncated cone shape closes a through-hole provided in the second workpiece such that a portion from an opening to an intermediate annular step portion fits the shape of the sealing portion of the first workpiece, a step of bringing an ultrasonic bonding tip into contact with an upper surface of the first workpiece in a state in which the sealing portion is inserted into the through-hole of the second workpiece; and a step of causing the ultrasonic bonding tip to undergo ultrasonic complex vibration so as to have ultrasonic vibration components in two directions perpendicular to a plane parallel to the top surface of the first workpiece.

[0010] The ultrasonically bonded structure of the present invention is A first workpiece has a sealing portion formed in a disk shape, a cylindrical shape, or an inverted truncated cone shape, and a second workpiece has a through hole formed so that the portion from the opening to the annular step portion in the middle fits the shape of the first workpiece, The outer surface of the first workpiece and the inner surface of the second workpiece that defines the portion of the through hole are solid-state welded together over the entire periphery, The peripheral portion of the lower surface of the first workpiece and the stepped portion of the through hole of the second workpiece are solid-state welded together over the entire periphery. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating the configuration of an ultrasonic bonding device according to an embodiment of the present invention; [Figure 2] 1 is a flowchart showing the procedure of an ultrasonic bonding method according to an embodiment of the present invention. [Figure 3] 10A and 10B are explanatory diagrams illustrating a method for sealing a through-hole in a housing with a lid member. [Figure 4] 1 is a diagram illustrating the configuration of an ultrasonically bonded structure according to an embodiment of the present invention; [Figure 5] 10A and 10B are explanatory diagrams illustrating a sealing method of a through-hole in a housing with a lid member as another embodiment. [Figure 6]10A and 10B are explanatory diagrams illustrating a sealing method of a through-hole in a housing with a lid member as another embodiment. [Figure 7] FIG. 10 is a diagram illustrating the configuration of an ultrasonic bonding structure according to another embodiment of the present invention. [Figure 8] 1A and 1B are explanatory diagrams showing a method of sealing a housing through-hole with a lid member as Prior Art 1. FIG. [Figure 9] 10A and 10B are explanatory diagrams showing a method of sealing a housing through-hole with a lid member as prior art 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] (composition) 1 includes an ultrasonic complex vibration device 10, a horn tip 140 (ultrasonic bonding tip), and an anvil 18. The anvil 18 may be omitted.

[0013] The ultrasonic complex vibration device 10 includes a first vibration element 110 having a substantially cylindrical shape, an intermediate vibration element 100 having a substantially cylindrical, cylindrical, or bottomed cylindrical shape, and a second vibration element 120 having a substantially cylindrical or bottomed cylindrical shape. The first vibration element 110, the intermediate vibration element 100, and the second vibration element 120 constitute "vibration elements."

[0014] The first vibration element 110 and the intermediate vibration element 100 are coaxially connected by a mechanical connecting mechanism (such as a bolt and / or a clamp mechanism) at the middle or intermediate portion of the ultrasonic complex vibration device 10. The intermediate vibration element 100 and the second vibration element 120 are coaxially connected by a mechanical connecting mechanism at the middle portion of the ultrasonic complex vibration device 10. The first vibration element 110, the intermediate vibration element 100, and the second vibration element 120 may be integrally configured rather than being mechanically connected.

[0015] The intermediate vibration element 100 may be a component of the first vibration element 110. That is, the first vibration element 110 may be composed of two vibration elements. In this case, the first vibration element 110 and the intermediate vibration element 100 may be integrally configured rather than being mechanically connected. The intermediate vibration element 100 may be a component of the second vibration element 120. That is, the second vibration element 120 may be composed of two vibration elements. In this case, the second vibration element 120 and the intermediate vibration element 100 may be integrally configured rather than being mechanically connected.

[0016] As shown in FIG. 1, the first vibration element 110 is provided with a piezoelectric body 112 whose axial direction (parallel to the first axis) is the piezoelectric polarization direction.

[0017] As shown in FIG. 1 , the intermediate vibration element 100 is formed with a substantially annular plate-shaped intermediate flange 102 that protrudes radially around its entire circumference at a central position in the axial direction. The intermediate vibration element 100 is configured to be clamped or supported around its entire circumference by a clamping mechanism (not shown) at least at the intermediate flange 102. If it is ensured that the intermediate vibration element 100 is supported by a mechanical support mechanism, the intermediate flange 102 may be omitted. As shown in FIG. 1 , the intermediate vibration element 100 has a substantially cylindrical shape with a substantially constant outer diameter in the axial direction behind the intermediate flange 102 (leftward in FIG. 1 ). As shown in FIG. 1 , the intermediate vibration element 100 has a substantially cylindrical shape (a shape in which a substantially truncated conical shape and a substantially cylindrical shape are coaxially connected) with a substantially constant outer diameter after continuously tapering partway toward the tip of the intermediate vibration element 100 (rightward in FIG. 1 ).

[0018] 1, the second vibration element 120 is provided with a frequency adjustment element 122 in the shape of a generally regular octagonal plate with rounded corners, which extends radially around the entire circumference at a midpoint in the axial direction of the second vibration element 120. The frequency adjustment element 122 adjusts the resonance frequencies of the longitudinal vibration component and the torsional vibration component of the ultrasonic vibration. The outer shape of the frequency adjustment element 122 may be a generally circular, generally elliptical, or generally regular n-polygonal plate (e.g., n = 4, 6, 8, 12, 16, etc.) plate, columnar, or frustum shape, which shares a common central axis with the second vibration element 120, or any combination thereof.

[0019] 1, the second vibration element 120 has a plurality of slits 124 formed on its outer surface behind the frequency adjustment element 122. A plurality of slits 124 may be formed on the outer surface of the second vibration element 120 ahead of the frequency adjustment element 122. The slits 124 extend obliquely in the second vibration element 120 when viewed from the side, or extend in the axial direction while being displaced in the circumferential direction in phase with each other. N (N=2, 3, ...) slits 124 may be arranged to have N-fold rotational symmetry (e.g., N=8, 12, or 16) around the central axis of the second vibration element 120.

[0020] 1, the second vibration element 120 is provided with a tip portion 126 of a generally regular octagonal shape with rounded corners that protrudes radially around the entire circumference at the tip position in the axial direction. Holes 128 (or through holes) are formed in the tip portion 126 at a plurality of locations spaced apart in the circumferential direction. The M (N=2, 3, ...) holes 128 may be arranged to have M-fold rotational symmetry (e.g., M=4) around the central axis of the second vibration element 120. A female thread is provided on the inner surface of the hole 128.

[0021] Horn tip 140 has a substantially truncated cone-shaped base portion and a tip portion that abuts against workpiece W1, which is the uppermost of first workpiece W1 and second workpiece W2. A male thread provided at the base end of horn tip 140 is threaded into a female thread provided in hole 128 in tip portion 126 of second vibration element 12, thereby removably fixing horn tip 140 to second vibration element 120. Horn tips 140 of various shapes are available, so that horn tips 140 can be appropriately replaced depending on the type of metal to be joined, etc.

[0022] The balancer for adjusting the phase difference between the longitudinal vibration and the torsional vibration at the tip 126 of the second vibration element 120, and hence at the horn tip 140, may be removably fixed to the tip 126 of the second vibration element 120 by screwing the male thread of the balancer into the female thread of the hole 128.

[0023] Anvil 18 is disposed so as to face the tip of horn tip 140 in the vertical direction. A first workpiece W1 and a second workpiece W2 as multiple workpieces are placed on the upper surface of anvil 18. Anvil 18 may be configured to passively or actively displace up and down in response to the pressure of horn tip 140 received through first workpiece W1 and second workpiece W2.

[0024] As shown in FIG. 1, the ultrasonic bonding apparatus according to one embodiment of the present invention further includes an operating device 20, a control device 22, a rotational driving device 220, a high-frequency power supply device 221, a translational driving device 222, and a status sensor 224.

[0025] The operation device 20 is configured, for example, by a display, and displays or outputs on the display the displacement amount of the pressure block and / or the time series of the pressure according to the output signal of the status sensor 224. The display may be configured by a touch panel display, and may be configured to accept a setting operation for allowing the user to directly or indirectly specify parameters, such as one of a plurality of bonding modes that determine a time series pattern of the target pressure.

[0026] The control device 22 is configured with a microcomputer, an arithmetic processing device (CPU, microprocessor, processor core, etc.), and a storage device (memory such as ROM and RAM). The control device 22 is configured to control the displacement operation of the pressure block by the translation drive device 222 based on a time series of the displacement amount of the pressure block represented by an output signal of a stroke sensor constituting the status sensor 224, for example. The control device 22 is configured to control the power supplied to the piezoelectric body 112 based on the amplitude (corresponding to a specified parameter) of the horn tip 140 represented by an output signal of an amplitude sensor constituting the status sensor 224, and thereby to control the ultrasonic vibration power of the vibration elements (first vibration element 110, intermediate vibration element 100, and second vibration element 120) and the ultrasonic vibration power of the horn tip 140.

[0027] The high-frequency power supply device 221 is configured to excite the first vibration element 110 in the axial direction by applying a high-frequency AC voltage to the piezoelectric element 112 of the first vibration element 110 in accordance with power supplied from a commercial power source (not shown).

[0028] The translational drive device 222 is equipped with a pressure block and is configured to apply pressure from the horn tip 140 to the first workpiece W1 and the second workpiece W2 by displacing a support mechanism such as a clamping mechanism that supports the intermediate vibration element 100 using the pressure block.

[0029] The status sensor 224 includes a stroke sensor that outputs a signal corresponding to the displacement of the pressure block that constitutes the translational drive device 222, as well as an amplitude sensor that outputs a signal corresponding to the amplitude (corresponding to a specified parameter) of the horn tip 140. The amplitude sensor may be a sensor module composed of an imaging device and a device that calculates the amplitude by analyzing an image captured by the imaging device. As the status sensor 224, a pressure sensor that outputs a signal corresponding to the pressure acting on the intermediate vibration element 100 from the pressure block of the translational drive device 222 (the pressure that the horn tip 140 applies to the first workpiece W1 and the second workpiece W2) may be provided, and the control device 22 may control the time series of the pressure to be constant or in a specified manner based on the output signal of the pressure sensor.

[0030] (Ultrasonic bonding method) The procedure of an ultrasonic bonding method according to one embodiment of the present invention, performed by the ultrasonic bonding apparatus 1, will be described with reference to the flowchart of FIG. 2. As shown in FIG. 3, the first workpiece W1 is a substantially disk-shaped metal cover member used to close a through-hole W20 formed in the second workpiece W2. The entire first workpiece W1 may constitute the sealing portion, or only a portion or a lower portion of the first workpiece W1 may constitute the sealing portion. The second workpiece W2 is a metal casing (e.g., a battery housing) or a wall material thereof, in which a through-hole W20 (e.g., an electrolyte injection port) is formed. The through-hole W20 of the second workpiece W2 has a shape in which a large-diameter, substantially cylindrical space and a small-diameter, substantially cylindrical space are coaxially stacked from top to bottom, with the diameter tapering midway. The second workpiece W2 has a substantially annular stepped portion W22 formed as the tapered portion of the through-hole W20.

[0031] As shown in Figure 3, the first workpiece W1 is inserted into the through hole W20 of the second workpiece W2, and the side surface of the first workpiece W1 abuts against the inner surface W21 that defines the large diameter portion of the through hole W20, and the bottom surface of the first workpiece W1 abuts against the step portion W22 of the second workpiece W2.

[0032] The ultrasonic complex vibration device 10 and the horn tip 140 are moved in the radial direction by the translational drive device 222 so as to approach the first workpiece W1 and the second workpiece W2 (FIG. 2 / STEP 112).

[0033] Furthermore, it is determined whether the pressure P that horn tip 140 receives from first workpiece W1 (and second workpiece W2) is equal to or greater than first specified pressure P1 (FIG. 2 / STEP 114). The pressure P that horn tip 140 receives from first workpiece W1 is measured based on the output signal of a pressure sensor that constitutes state sensor 224. When the tip of horn tip 140 is separated from workpiece W1, P=0. For example, as shown in FIG. 3, when the tip of horn tip 140 comes into contact with first workpiece W1 that is inserted into through-hole W20 of second workpiece W2, a reaction force is received, so that P>0.

[0034] If the determination result is negative (FIG. 2 / STEP 114...NO), the translational drive device 222 moves the ultrasonic complex vibration device 10 and the horn tip 140 in the radial direction so as to approach the first workpiece W1 inserted into the through-hole W20 of the second workpiece W2 (FIG. 2 / connector X1 →STEP 112). As a result, the position of the horn tip 140, and therefore the static pressure applied from the horn tip 140 to the first workpiece W1 and the second workpiece W2, is adjusted to be within a specified static pressure range (e.g., 200 N to 800 N).

[0035] If the determination result is affirmative (FIG. 2 / STEP 114...YES), ultrasonic vibrations are generated in the vibration elements (FIG. 2 / STEP 116). Specifically, in response to power being supplied to the high-frequency power supply device 221 from a commercial power source (not shown) via a slip ring or the like, the high-frequency power supply device 221 applies a high-frequency AC voltage to the piezoelectric body 112 of the first vibration element 110. This causes the first vibration element 110 to vibrate in its axial direction at, for example, approximately 20 KHz, generating ultrasonic vibrations. The ultrasonic vibrations are transmitted from the first vibration element 110 to the intermediate vibration element 100 in its axial direction, and the amplitude of the ultrasonic vibrations is amplified. Furthermore, the ultrasonic vibrations with amplified amplitude are transmitted from the intermediate vibration element 100 to the second vibration element 120 in its axial direction.

[0036] In this way, a portion of the longitudinal vibration component (axial component of the second vibration element 120) of the ultrasonic vibration transmitted to the second vibration element 120 is converted into a torsional vibration component by the plurality of slits 124 formed on the outer surface of the second vibration element 120. Then, a composite vibration generated by combining the longitudinal vibration component and the torsional vibration component is transmitted to the horn tip 140 fixed to the tip of the second vibration element 120.

[0037] In response, the horn tip 140 displaces or vibrates in a circular or elliptical orbit on a plane perpendicular to the contact direction of the first workpiece W1. As a result, the amplitude and ultrasonic vibration power of the horn tip 140 gradually increase from the vibration start time t=t0. During this process, impurities are removed from the contact surfaces of the first workpiece W1 and the second workpiece W2, and plastic deformation of the contact surfaces of the first workpiece W1 and the second workpiece W2 may be promoted. After the rate of increase in the amplitude and ultrasonic vibration power of the horn tip 140 significantly decreases at time t=t1, the amplitude and ultrasonic vibration power of the horn tip 140 gradually increase. This is because the oxide coatings and other metals constituting the joining surfaces of the first workpiece W1 and the second workpiece W2 are removed, revealing clean, activated metal atoms at the joining surfaces. The temperature rise due to frictional heat activates the atomic movement, generating a mutual attraction between the atoms.

[0038] At this time, the composite vibration is applied to the first workpiece W1 and the second workpiece W2 while adjusting the amount of pressing of the first workpiece W1 and the second workpiece W2 by the horn tip 140 and / or the static pressure applied to the first workpiece W1 and the second workpiece W2. As a result, as shown in Fig. 4, the outer surface and the peripheral edge of the lower surface of the first workpiece W1 can be solid-state welded to the stepped portion W22 of the second workpiece W2 over the entire circumference.

[0039] It is determined whether the time derivative δA (= current amplitude A(k) - previous amplitude A(k-1)) of the amplitude A of the horn tip 140 is negative and whether the amplitude A is equal to or less than the reference amplitude A0 (FIG. 2 / STEP 118). An amplitude sensor constituting the state sensor 224 optically measures the amplitude A at a specified location (e.g., a location where the amplitude is relatively large) of the horn tip 140. Instead of this determination process, it may be determined whether the amplitude A has decreased by the reference amplitude A0 (or a reference ratio based on the maximum value) using the maximum value at the time when the amplitude A started to decrease as a reference. For example, the reference amplitude A0, such as one of multiple joining modes for which the reference amplitude A0 is determined, may be directly or indirectly specified via a touch panel display constituting the operation device 20.

[0040] If the determination result is negative (FIG. 2 / STEP 118...NO), ultrasonic vibrations are continuously generated in the vibration element (FIG. 2 / connector X2 →STEP 116). On the other hand, if the determination result is positive (FIG. 2 / STEP 118...YES), the translational drive device 222 moves the ultrasonic complex vibration device 10 and the horn tip 140 away from the first workpiece W1 and the second workpiece W2 (FIG. 2 / STEP 122).

[0041] Furthermore, it is determined whether the pressure P that the horn tip 140 receives from the first workpiece W1 (and the second workpiece W2) has become equal to or less than a second designated pressure P2 (FIG. 2 / STEP 124). The second designated pressure P2 is set to a value smaller than the first designated pressure P1, for example, 0 or a very small value.

[0042] If the determination result is negative (FIG. 2 / STEP 124...NO), the translational drive device 222 moves the ultrasonic complex vibration device 10 and the horn tip 140 away from the first workpiece W1 and the second workpiece W2 (FIG. 2 / connector X4 →STEP 122). This reduces the radial position of the horn tip 140, and therefore reduces the static pressure applied by the horn tip 140 to the first workpiece W1 and the second workpiece W2.

[0043] If the determination result is positive (FIG. 2 / STEP 124...YES), the generation of ultrasonic vibrations in the vibration element is stopped (FIG. 2 / STEP 126). For example, after the amplitude of horn tip 140 changes from increasing to decreasing and falls below reference amplitude A0 at time t=t2, the ultrasonic power of horn tip 140 is controlled to become 0 with a slight response delay. This stops the series of processes.

[0044] (effect) With the ultrasonic bonding device configured as described above, the outer surface and the peripheral portion of the lower surface of the first workpiece W1 are ultrasonically or solid-state bonded to the inner surface of the large-diameter portion of the through-hole W20 of the second workpiece W2 and the stepped portion W22 along the entire periphery. Residual stress between the first workpiece W1 and the second workpiece W2 is reduced, thereby improving the sealing strength of the through-hole W20 of the second workpiece W2 by the cover member serving as the first workpiece W1 and the pressure resistance of the housing serving as the second workpiece W2. Furthermore, since the first workpiece W1 only needs to be formed in a generally disk-like or generally cylindrical shape, manufacturing costs are reduced compared to the cover member 51 of the prior art (see FIG. 5). Furthermore, even if foreign matter such as electrolyte is attached to the side of the through hole W20, the horn tip 140 applies ultrasonic complex vibration, circular vibration, or elliptical vibration to the first workpiece W1, thereby removing the foreign matter from the joining surface of the first workpiece W1 and the second workpiece W2, thereby avoiding a decrease in joining strength due to the foreign matter.

[0045] (Another embodiment of the present invention) In the above embodiment, the first work W1 (or the sealed portion of the first work W1) and the large-diameter space of the through-hole W20 provided in the second work W2 and into which the first work W1 is inserted are both approximately disk-shaped or approximately cylindrical. In contrast, in other embodiments, the first work W1 (or the sealed portion of the first work W1) and / or the large-diameter space of the through-hole W20 provided in the second work W2 and into which the first work W1 is inserted may be approximately truncated cone-shaped (inverted) with the bottom side facing up.

[0046] For example, as shown in Fig. 5, the first workpiece W1 may have a first sealing portion having a generally inverted truncated cone shape and a second sealing portion having a generally cylindrical or disc shape connected to the upper end of the first sealing portion and having a diameter generally the same as that of the upper end of the first sealing portion. For example, as shown in Fig. 5, the second workpiece W2 may have a generally two-stage cylindrical through-hole W20, the large diameter portion of which is larger than the lower end of the first sealing portion and smaller than the upper end of the first sealing portion (and therefore the second sealing portion). With the first sealing portion of the first workpiece W1 inserted into the large diameter portion of the through-hole W0, the first workpiece W1 is pushed downward into the horn tip 140, and ultrasonic complex vibrations are applied to the first workpiece W1 from the horn tip 140.

[0047] As a result, as shown in Figure 6, following the first sealing portion of the first work W1, which is approximately inverted truncated cone-shaped, a portion of the second sealing portion is deformed into an approximately cylindrical shape to fit the shape of the large diameter portion of the through hole W20 of the second work W2, and the first work W1 is gradually inserted to fit the shape of the through hole W20 of the second work W2.

[0048] 7, the first workpiece W1, deformed into a substantially two-stage cylindrical shape, is solid-state welded at the side of the small-diameter cylindrical portion to the inner surface W21 that defines the large-diameter portion of the through hole W20, at the peripheral portion of the lower end surface to the substantially annular stepped portion W22 that is the reduced-diameter portion of the through hole W20, and at the lower end surface of the large-diameter portion (flange portion) to the peripheral portion of the through hole W20 in the second workpiece W2. As a result, the bonding area between the first workpiece W1 and the second workpiece W2 is further increased. In other words, the sealing strength of the through hole W20 in the second workpiece W2 by the first workpiece W1 (or the sealing portion derived from the first sealing portion and the second sealing portion) is improved.

[0049] In the above embodiment, the amplitude A of the horn tip 140 was measured as a specified parameter that changes depending on the progress of joining the first workpiece W1 and the second workpiece W2, but in other embodiments, the axial displacement amount, displacement speed and / or displacement acceleration of the vibration element (e.g., the second vibration element 120) may be measured as a specified parameter. [Explanation of symbols]

[0050] 10. Ultrasonic complex vibration device 100...Intermediate vibration element 102...Intermediate flange 110...First vibration element 112. Piezoelectric material 120...Second vibration element 122...Frequency adjustment element 124. Slit 140...Horn tip (Ultrasonic bonding tip) 18. Anvil 20‥Operation device 22. Control device 220 Rotational drive device 221‥High frequency power supply equipment 222...Translation drive device 224...Status sensor W1: First workpiece (lid part) W2: Second workpiece (casing) W20...Through hole W22‥ step difference part.

Claims

1. A method for joining a first workpiece and a second workpiece such that a sealing portion of a first workpiece formed in a disk, column, or inverted truncated cone shape closes a through-hole provided in a second workpiece such that a portion from an opening to an intermediate annular step portion conforms to the shape of the sealing portion of the first workpiece, a step of bringing an ultrasonic bonding tip into contact with an upper surface of the first workpiece in a state in which the sealing portion is inserted into the through-hole of the second workpiece; and a step of subjecting the ultrasonic bonding tip to ultrasonic complex vibration so as to have ultrasonic vibration components in two directions perpendicular to a plane parallel to the top surface of the first workpiece. Ultrasonic bonding method.

2. An ultrasonic bonding program for causing a computer constituting an ultrasonic bonding apparatus to execute the method according to claim 1.

3. A first workpiece has a sealing portion formed in a disk shape, a cylindrical shape, or an inverted truncated cone shape, and a second workpiece has a through hole provided so that the portion from the opening to the annular step portion in the middle fits the shape of the first workpiece, an outer surface of the first workpiece and an inner surface of the second workpiece that defines the portion of the through hole are solid-state welded together over the entire periphery; The peripheral portion of the lower surface of the first workpiece and the stepped portion of the through hole of the second workpiece are solid-phase welded together over the entire periphery. Ultrasonic bonded structure.

4. 4. The ultrasonically bonded structure according to claim 3, A battery including a cover member of the first work and a housing of the second work having an electrolyte injection port as the through hole. Ultrasonic bonded structure.

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