Ultrasonic welding apparatus and ultrasonic welding method

Abstract

To provide an ultrasonic welding apparatus and an ultrasonic welding method capable of accurately measuring a pressing force of a horn and adjusting a down stroke of the horn to meet a preset pressing force.SOLUTION: An ultrasonic welding apparatus includes: a pressing force measuring anvil 110 including a pressing force measuring sensor; a horn 120 which is installed to vertically move above the pressing force measuring anvil and presses the pressing force measuring anvil when moving downward; a horn down stroke adjustment part that can adjust a down stroke of the horn so that a pressing force of the horn is within a preset pressing force range; and a welding anvil 140 on which welding target members W to be welded by the horn are placed and supported and of which a position is changed to a position of the pressing force measuring anvil so that the welding anvil is positioned under the horn after the down stroke of the horn is adjusted to be within the preset pressing force range.SELECTED DRAWING: Figure 2

Description

Technical Field

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

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0099891 filed on Jul. 29, 2021, and all contents disclosed in the corresponding Korean patent application are incorporated herein by reference.

Background Art

[0003] Recently, rechargeable secondary batteries have been widely used as an energy source for wireless mobile devices. In addition, secondary batteries have also attracted attention as an energy source for electric vehicles, hybrid electric vehicles, etc., which are proposed as solutions for solving air pollution such as existing gasoline vehicles and diesel vehicles that use fossil fuels. Therefore, the types of applications using secondary batteries are very diversified due to the advantages of secondary batteries, and it is expected that secondary batteries will be applied to more fields and products in the future than now.

[0004] One, two, three, or four battery cells are used for small mobile devices. For medium and large-sized devices such as automobiles, due to the need for high output and large capacity, a battery module in which a number of battery cells are electrically connected or a battery pack in which a number of the above battery modules are connected is used. Since the above battery module is preferably manufactured in a small size and weight, prismatic batteries, pouch-type batteries, etc. with a small capacity-to-weight ratio are mainly used as battery cells for medium and large-sized battery modules.

[0005] An electrode assembly in which a number of unit cells are stacked is provided in the above battery cell, and the electrical connection of the above unit cells is made by welding electrode tabs led out from the unit cells to each other. Also, for the electrical connection between the above battery cells or the electrical connection with an external device, the mass of the welded electrode tabs is welded to an electrode lead.

[0006] An ultrasonic welding method is used for welding between such electrode tabs and for welding between an electrode tab and an electrode lead.

[0007] Figure 1 is a schematic diagram showing the process of ultrasonic welding of an electrode tab and an electrode lead.

[0008] Tab W1 led out from the electrode assembly is stacked vertically with electrode lead W2 and is positioned on anvil 20 of an ultrasonic welding apparatus. A horn 10 that provides vibration for ultrasonic bonding is positioned on the anvil 20. The horn 10 descends onto tab W1 and lead W2 which are members to be welded, applies vibration while pressing the members to be welded, and ultrasonically welds the tab and the lead.

[0009] During such ultrasonic welding, since the horn 10 welds while pressing the members to be welded, the pressing force of the horn 10 affects the welding quality. For example, if the pressing force of the horn 10 is weak during ultrasonic welding, a poor weld may occur where tab W1 and lead W2 separate. On the contrary, if the pressing force of the horn 10 is excessively strong, problems such as disconnection of the tab or lead, or premature wear of the horn or anvil may occur.

[0010] Therefore, during ultrasonic welding using a horn and an anvil, it is important to maintain the pressing force of the horn within a set range or at an optimal pressing force. However, conventionally, there has been no method to accurately confirm the pressing force of the horn. For example, even if a pressure sensor is installed on the anvil or the like to measure the pressing force of the horn, since ultrasonic vibration is applied during welding, the pressing force of the horn cannot be accurately measured. Also, each time the member to be welded is replaced or a worn horn or anvil is replaced, the pressing force of the horn changes slightly, so there is a technical problem that it is difficult to perform ultrasonic welding with uniform welding quality.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention was devised to solve the above problems, and an object thereof is to provide an ultrasonic welding apparatus and an ultrasonic welding method that can accurately measure the pressing force of a horn and adjust the descending stroke of the horn so as to obtain a set pressing force.

Means for Solving the Problems

[0013] The ultrasonic welding apparatus according to the present invention includes an anvil for measuring pressing force provided with a pressing force measuring sensor; a horn installed above the anvil for measuring pressing force so as to be movable up and down, and pressing the anvil for measuring pressing force when descending; a horn descending stroke adjusting unit capable of adjusting the descending stroke of the horn so that the pressing force of the horn is included within a set pressing force range; and a welding anvil on which a member to be welded welded by the horn is placed and supported, and which is positioned below the horn after the descending stroke of the horn is adjusted so as to be included within the set pressing force range and is positioned below the horn after being repositioned with respect to the anvil for measuring pressing force.

[0014] In a specific example, the ultrasonic welding apparatus of the present invention may further include a pressing force indicator connected to the pressing force measuring sensor and representing the pressing force sensed by the pressing force measuring sensor.

[0015] In a specific example, the pressing force measuring sensor may be installed in an installation groove formed at the center of the upper surface of the anvil for measuring pressing force.

[0016] In a more specific example, the anvil for measuring pressing force includes extended protrusions protruding from one or both sides of the upper part of the body, and the pressing force measuring sensor may be installed in an installation groove formed at the center of the upper surface of the extended protrusion.

[0017] As a specific example, when the horn pressurizes the anvil for pressure measurement, ultrasonic vibration may not be applied to the horn.

[0018] As an example, it can further include a control unit that compares the measured pressurizing force of the horn with the set pressurizing force range and controls the horn lowering stroke adjustment unit so that the pressurizing force of the horn is included in the set pressurizing force range.

[0019] In a specific example, the control unit can compare the measured pressurizing force of the horn with the set optimum pressurizing force and repeatedly control the horn lowering stroke adjustment unit so that the pressurizing force of the horn becomes the optimum pressurizing force.

[0020] As an example, the horn lowering stroke adjustment unit is a hydraulic or pneumatic cylinder, and the control unit can control the hydraulic or pneumatic pressure supplied to the hydraulic or pneumatic cylinder to adjust the lowering stroke of the horn.

[0021] As another example, the horn lowering stroke adjustment unit is a linear movement mechanism that moves by a servo motor, and the control unit can control the rotation amount of the servo motor to adjust the lowering stroke of the horn.

[0022] In another embodiment of the present invention, the anvil for pressure measurement and the anvil for welding are installed at a predetermined interval and are relatively movable with respect to the horn below the horn, and the positions of the anvil for pressure measurement and the anvil for welding with respect to the horn can be changed by the relative movement of the anvil for pressure measurement and the anvil for welding with respect to the horn.

[0023] As a specific example, the ultrasonic welding apparatus of the above embodiment further includes a movable plate that slides relative to the horn at the lower part of the horn, and the anvil for pressure measurement and the anvil for welding are fixedly installed separately. By sliding the movable plate relative to the horn, the positions of the anvil for pressure measurement and the anvil for welding relative to the horn can be varied.

[0024] The member to be welded can be a plurality of electrode tabs extending from the electrode assembly of the secondary battery, or the electrode tabs and electrode leads.

[0025] The ultrasonic welding method as another aspect of the present invention includes the steps of: arranging an anvil for pressure measurement provided with a pressure measurement sensor at the lower part of the horn; lowering the horn to press the anvil for pressure measurement, and measuring the pressing force of the horn by the pressure measurement sensor; comparing the measured pressing force of the horn with a set pressing force range, and adjusting the descending stroke of the horn so that the pressing force of the horn is included in the set pressing force range; after the descending stroke of the horn is adjusted, changing the position of the anvil for welding on which the member to be welded is placed and supported to position the anvil for welding at the lower part of the horn; and lowering the horn at the adjusted descending stroke to ultrasonically weld the member to be welded on the anvil for welding.

[0026] As a specific example, when the horn presses the anvil for pressure measurement, ultrasonic vibration may not be applied to the horn.

[0027] As a specific example, the descending stroke of the horn can be repeatedly adjusted until the measured pressing force of the horn reaches the set optimum pressing force, and the horn can be lowered to the anvil for welding at the descending stroke corresponding to the optimum pressing force to weld the member to be welded.

Advantages of the Invention

[0028] According to the present invention, by checking the pressing force of the horn before ultrasonic welding and adjusting it to the set pressing force range or the optimum pressing force to prevent the occurrence of welding defects, the quality of ultrasonic welding can be improved.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

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Modes for Carrying Out the Invention

[0030] Hereinafter, the present invention will be described in detail. Before that, terms or words used in this specification and the claims should not be construed in a limited sense in accordance with their ordinary or dictionary meanings. Instead, in accordance with the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best possible way, they should be construed in a meaning and concept that conforms to the technical idea of the present invention.

[0031] In this application, terms such as "comprising" and "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Also, when a part such as a layer, film, region, or plate is said to be "on" another part, this includes not only the case where it is directly "on" the other part but also the case where there are other parts in between. Conversely, when a part such as a layer, film, region, or plate is said to be "under" another part, this includes not only the case where it is directly "under" the other part but also the case where there are other parts in between. Also, being "disposed on" in this application can include the case of being disposed not only on the upper part but also on the lower part.

[0032] On the other hand, in this application, the "length direction" means the direction in which the electrode lead of the battery cell protrudes.

[0033] Hereinafter, the present invention will be described in detail.

[0034] The ultrasonic welding apparatus of the present invention includes an anvil for measuring pressing force equipped with a pressing force measurement sensor; a horn installed above the anvil for measuring pressing force so as to be movable up and down, and pressing the anvil for measuring pressing force when descending; a horn descending stroke adjustment unit capable of adjusting the descending stroke of the horn so that the pressing force of the horn is within a set pressing force range; and a welding anvil on which a weldment to be welded by the horn is placed and supported, and which is positioned below the horn after the descending stroke of the horn is adjusted so as to be within the set pressing force range and is positioned to be changed in position from the anvil for measuring pressing force.

[0035] The present invention includes an anvil for measuring pressing force capable of measuring the pressing force of the horn, and can measure in advance the pressing force of the horn, which is closely related to the welding quality. Further, the present invention includes a horn descending stroke adjustment unit capable of adjusting the descending stroke of the horn so that the pressing force of the horn measured by the anvil for measuring pressing force is within a set pressing force range, and can set the pressing force of the horn within the set pressing force range. When the descending stroke of the horn is adjusted so that the pressing force of the horn is within the set pressing force range, the positions of the anvil for measuring pressing force and the welding anvil on which the weldment is placed and supported are changed, and the weldment on the welding anvil is welded with the adjusted descending stroke of the horn, thereby preventing welding defects such as poor welding and preventing the horn and the anvil from rapidly wearing.

[0036] (First Embodiment) FIG. 2 is a schematic view showing the configuration of an ultrasonic welding apparatus 100 according to an embodiment of the present invention.

[0037] Referring to FIG. 2(a), the ultrasonic welding apparatus 100 of the present invention includes a pressure measuring anvil 110 equipped with a pressure measuring sensor 115. The pressure measuring sensor 115 is installed on the pressure measuring anvil 110 to measure the pressure transmitted from the horn 120. Specifically, the pressure measuring sensor 115 can employ a load sensing sensor such as a load cell. The load cell can convert the pressure applied to the load cell through a strain gauge into an electrical signal and output it to display the pressure. The type of the pressure measuring sensor 115 is not greatly limited as long as it can indicate the numerical value of the pressure. For example, various forms of load cells such as a beam load cell and a cylindrical load cell can be used.

[0038] FIG. 3 is a schematic diagram of the pressure measuring anvil 110 and the pressure indicator 117 which are components of the ultrasonic welding apparatus 100, and FIG. 4 is a plan view and a side view of the pressure measuring anvil 110 of FIG. 3.

[0039] As shown in FIG. 3, the present invention can further include a pressure indicator 117 that digitizes and outputs the pressure applied to the pressure measuring sensor 115 as an electrical signal. The pressure measuring sensor 115 is electrically connected to the pressure indicator 117 by a wire 116, and the pressure applied to the pressure measuring sensor 115 is digitized into an electrical signal and appears in the pressure display portion 117a of the pressure indicator 117 as a value that can be visually confirmed. Further, the pressure indicator 117 is provided with a predetermined operation button 117b. Since such a load cell and the pressure indicator 117 are commonly known pressure measuring members or load measuring members, specific descriptions thereof are omitted in this specification. Although a load cell is exemplified as the pressure measuring sensor in this specification, it goes without saying that other suitable types of pressure measuring sensors that can measure the pressure or load of the horn can be adopted.

[0040] The pressure measurement sensor 115 is preferably installed at the center of the upper surface of the anvil 110 for pressure measurement. In the present invention, it is important to accurately measure the pressure applied to the horn 120 and find the downward stroke H of the horn 120 that can apply the set pressure range or the optimal pressure. Therefore, when the pressure measurement sensor 115 is installed on the side or lower part of the anvil 110 for pressure measurement, the pressure applied to the horn cannot be accurately measured. Thus, the pressure measurement sensor 115 is installed on the upper surface 111A of the anvil 110 for pressure measurement that is directly pressurized by the horn. Also, if the pressure measurement sensor 115 is installed offset to one side of the upper surface of the anvil, the accurate pressure cannot be reflected in the same way. Therefore, the pressure measurement sensor 115 is installed at the center of the upper surface of the anvil. For this purpose, as shown in FIG. 4, the anvil 110 for pressure measurement is provided with an installation groove 113 for installing the pressure measurement sensor 115 at the center of its upper surface.

[0041] The above anvil 110 for pressure measurement can be of the same shape and material as a normal anvil for welding. However, when the size of the member to be welded is small, the size of the anvil for welding also becomes small. In particular, the electrode tabs and electrode leads of secondary batteries are very small in size, so the size of the anvil for welding these is relatively small. In this case, if an anvil of the same size and shape as the anvil for welding is used for pressure measurement, sufficient space for installing the pressure measurement sensor on the anvil cannot be ensured. In order to ensure space for installing the pressure measurement sensor 115, as shown in FIGS. 3 and 4, an anvil 110 for pressure measurement processed to have a shape different from that of the anvil 140 for welding can be used. The above anvil 110 for pressure measurement includes a body part 111, fastening parts 114 protruding from both sides of the body part, and an extended protruding part 112 formed on the upper part of the body part.

[0042] As shown in Fig. 4, the above-mentioned extended protrusion 112 protrudes from both sides of the upper part of the body part 111 to provide a larger installation surface. However, the extended protrusion 112 may also protrude from one side of the upper part of the body part. The protruding direction, size, shape, etc. of the extended protrusion 112 can be appropriately changed in consideration of the size and shape of the sensor to be installed. An installation groove 113 is formed at the center of the upper surface 112A of the above-mentioned extended protrusion 112, and the pressure measurement sensor 115 can be installed in this installation groove 113. Fastening parts 114 are provided on both side parts of the body part 111 of the anvil 110 for pressure measurement, and fastening holes 114a for installing the anvil 110 for pressure measurement on a support member such as a base are formed in the fastening parts. Therefore, the above-mentioned anvil 110 for pressure measurement can be fixedly coupled to a support member such as a base through the fastening hole 114a with a fastening member C such as a bolt.

[0043] In a normal welding anvil, uneven portions are formed on the surface to press and press-fit the member to be welded during ultrasonic vibration (see Fig. 5). However, since the above-mentioned anvil 110 for pressure measurement is not for welding, no protrusions are formed on the upper surface.

[0044] Referring to Fig. 2 again, a horn 120 is installed above the above-mentioned anvil 110 for pressure measurement so as to be able to move up and down. The above-mentioned horn 120 is for providing vibration for ultrasonic bonding at the bonding site of the member to be welded W. At the site where it contacts the member to be welded W, uneven portions that can form press-fit marks on the member to be welded located above can be provided to effectively transmit vibration. The horn 120 is also called a sonotrode and has an extension part 121 that contacts the member to be welded at its tip. However, such a shape of the horn is only an example, and it goes without saying that other forms of horns capable of performing ultrasonic welding can be adopted. Since the horn 120 has its own weight, the pressure of the horn due to its own weight can be measured when the horn 120 descends. However, if necessary, a separate pressing part (not shown) can be installed above the horn 120 to increase the pressing force of the horn. For example, a drive cylinder driven by a separate drive part above the horn can be adopted as the pressing part to additionally press the horn.

[0045] The horn 120 is connected to an ultrasonic generator G that generates ultrasonic waves, a transducer T that converts ultrasonic waves into vibrations, a booster B that amplifies the amplitude of the transducer, and the like. Since the ultrasonic generator G, the transducer T, and the booster B are known configurations commonly used in an ultrasonic welding apparatus, a specific description thereof will be omitted.

[0046] The horn 120 can be arranged to be movable up and down above the anvil 110 for measuring the pressing force alone or together with other ultrasonic welding members such as a booster. When the horn 120 descends toward the anvil 110 for measuring the pressing force and the horn presses the pressing force measuring sensor 115 (for example, a load cell) on the anvil 110 for measuring the pressing force, the pressing force of the horn is measured. When measuring the pressing force of the horn by the pressing force measuring sensor, ultrasonic vibrations are not applied to the horn 120. This is because if ultrasonic vibrations are applied, even if the horn 120 descends with the same downward stroke, the pressing force of the horn 120 will be variable and an accurate pressing force cannot be measured.

[0047] A horn lowering stroke adjustment unit 130 is provided for adjusting the raising or lowering stroke of the horn 120. A known vertical movement mechanism can be adopted as such a stroke adjustment unit. For example, a hydraulic or pneumatic cylinder can be installed at the lower part of a support base P that supports the horn 120, and hydraulic or pneumatic pressure can be supplied to the cylinder to raise and lower the horn. As an example of a pneumatic cylinder, a single-acting cylinder equipped with one air intake port or a double-acting cylinder equipped with air intake ports on the inlet side and the outlet side respectively can be adopted. Alternatively, a linear movement mechanism connected to a servo motor, such as a ball screw and a ball nut, can be used to raise and lower the horn. In this case, an LM guide rail or the like for guiding the movement of the linear movement mechanism can be adopted as needed. In addition, other vertical movement mechanisms or linear movement mechanisms commonly used in the technical field can be used as the horn lowering stroke adjustment unit. In this embodiment, a pneumatic cylinder 130 equipped with a cylinder body 131 and a cylinder rod 132 is introduced as the horn lowering stroke adjustment unit.

[0048] FIG. 6 is a schematic diagram showing the adjustment process of the horn lowering stroke according to the present invention.

[0049] The pressing force of the horn 120 can be expressed by the stroke in which the horn descends. That is, when the horn 120 descends relatively more toward the member to be welded, the pressing force of the horn received by the member to be welded W increases. On the contrary, when the descending stroke of the horn becomes shorter, the pressing force of the horn received by the member to be welded decreases. That is, the pressing force of the horn 120 can be expressed or converted by the descending stroke of the horn, and the pressing force of the horn can be adjusted by adjusting the descending stroke. The horn descending stroke adjusting unit 130 such as the hydraulic or pneumatic cylinder or the servo motor and the linear movement mechanism coupled thereto described above can be adjusted so that the pressing force of the horn 120 is included in the set pressing force range. However, for this purpose, measurement of the pressing force of the horn must be performed first. As described above, the pressing force of the horn 120 is variable during vibration, and the pressing force of the horn can vary depending on the type of the member to be welded W, or replacement of the member to be welded or replacement of the horn and anvil. Therefore, as shown in FIG. 6, first, the horn 120 is lowered with the anvil 110 for pressing force measurement to confirm the (initial) pressing force of the horn. If this pressing force is different from the set pressing force range, the descending stroke of the horn can be varied by the horn descending stroke adjusting unit 130 and the pressing force of the horn can be repeatedly measured. At this time, since the pressing force of the horn is displayed in real time by the pressing force indicator 117 described above, the descending stroke of the horn 120 can be adjusted while comparing whether the measured pressing force is included in the set pressing force range. For example, the operator can check the pressing force value of the pressing force indicator 117 and adjust the hydraulic pressure or pneumatic pressure to adjust the length of the lifting and lowering of the cylinder rod 132 to adjust the descending stroke of the horn. Alternatively, the descending stroke of the horn can be adjusted by controlling the rotation amount of a servo motor (not shown) to control the movement amount of the linear movement mechanism.

[0050] Referring again to Fig. 2(a), the horn 120 is supported on the support base P together with the booster B, and the support base P is coupled to the pneumatic cylinder 130. Specifically, the pneumatic cylinder 130 includes a cylinder body 131 and a cylinder rod 132 that protrudes from and retracts into the cylinder body 131, and the cylinder rod is coupled to the support base P.

[0051] To stably support the horn 120, the pneumatic cylinder 150 is installed on the base 150. In Fig. 2, the anvil 110 for measuring the pressing force is also shown as being installed together on the base 150, but the anvil 110 for measuring the pressing force may be installed on a separate support member.

[0052] After the downward stroke H of the horn is adjusted by the horn downward stroke adjustment unit 130 so that the downward stroke of the horn 120 is included in the set pressing force range, the anvil 140 for welding, which is positionally changed with the anvil 110 for measuring the pressing force, is provided.

[0053] Fig. 5 is a perspective view showing an example of the anvil 140 for welding, which is a component of the ultrasonic welding apparatus 100 of the present invention.

[0054] Referring to Fig. 5, the anvil 140 for welding includes a body portion 141 and a fastening portion 142 having fastening holes 142a into which fastening members can be inserted on the left and right sides of the body portion. Further, on the upper surface 141A of the body portion 141, uneven portions capable of forming press-fit marks on the bottom surface of the member to be welded are provided. The illustrated form of the anvil for welding is merely an example and is not necessarily limited to the anvil of the above form. Since the anvil for welding is the portion where ultrasonic welding is actually performed by the horn, the member to be welded is placed and supported on the upper portion of the anvil for welding. That is, as shown in Fig. 1, for example, when the member to be welded W is the electrode tab W1 and the electrode lead W2 extending from the electrode assembly of the secondary battery, the electrode tab and the electrode lead are laminated and positioned on the anvil 140 for welding.

[0055] Referring to FIG. 2(b), a welding anvil 140 is shown being repositioned with a pressure measuring anvil 110 and installed at the lower part of the horn 120. The operator can manually change or replace the positions of the pressure measuring anvil 110 and the welding anvil 140. In this case, the fastening member C is separated from the fastening part 114 of the pressure measuring anvil 110 described above, and the pressure measuring anvil 110 is removed from the base 150 or the like. Thereafter, the welding anvil 140 can be placed at the position where the pressure measuring anvil 110 was installed, the fastening member C can be installed at the fastening part 141 of the welding anvil 140, and the welding anvil 140 can be installed at the lower part of the horn. However, the positions of the pressure measuring anvil and the welding anvil may be automatically changed using a separate moving member as described later.

[0056] FIG. 7 is a schematic diagram showing that welding is performed according to the embodiment of FIG. 2.

[0057] In FIG. 7, after the downward stroke H of the horn is adjusted to be within the set pressure range, a state is shown where the welding anvil 140 is positioned on the base 150 after being repositioned with the pressure measuring anvil 110. In this case, the pressure of the horn 120 is confirmed by the pressure measuring sensor 115 of the pressure measuring anvil, and the downward stroke of the horn is adjusted so that the pressure is compared with the set pressure and is within the set pressure range. Therefore, the horn 120 descends to the welded member of the welding anvil 140 by only the downward stroke H corresponding to the set pressure. Thereafter, as shown in FIG. 7, the horn 120 can ultrasonically weld the welded member W on the welding anvil with the set pressure by the ultrasonic vibration transmitted to the ultrasonic generator G - transducer T - booster B.

[0058] (Second Embodiment) FIGS. 8 and 9 are schematic diagrams showing the configuration of an ultrasonic welding apparatus 100' according to another embodiment of the present invention.

[0059] Referring to FIGS. 8 and 9, the ultrasonic welding apparatus 100' of this embodiment may further include a control unit 160 that compares the measured pressing force of the horn with the set pressing force range and controls the horn lowering stroke adjustment unit 130 so that the pressing force of the horn is included in the set pressing force range.

[0060] That is, this embodiment is provided with a control unit 160 that automatically controls the horn lowering stroke adjustment in relation to the confirmation of the pressing force of the horn 120. As shown in FIG. 8, the control unit 160 is connected to the pneumatic cylinder of the horn lowering stroke adjustment unit 130 and can automatically lower the horn 120 from the pressing force measurement stage. When the control unit 160 operates the horn lowering stroke adjustment unit 130 and the horn descends to the anvil 110 for pressing force measurement, the pressing force of the horn measured by the pressing force measurement sensor 115 is displayed on the pressing force indicator 117, and the control unit 160 can receive the transmission of this pressing force data. Further, the control unit 160 compares the measured pressing force of the horn 120 with the set pressing force range, and when the measured pressing force of the horn is outside the set pressing force range, the horn lowering stroke adjustment unit 130 can be adjusted. For example, if the set pressing force range of the electrode tab and the electrode lead is 150 to 200 kfg and the measured pressing force is less than 150 kgf, the control unit 160 increases the rotation amount of the hydraulic / pneumatic control or the servo motor to increase the lowering stroke of the horn until the pressing force of the horn becomes 150 kgf or more. At this time, the pressing force measurement sensor 115 (load cell) continuously measures the pressing force of the horn due to the increase in the lowering stroke, and the pressing force can be displayed on the display unit 117a of the pressing force indicator. The control unit 160 can save the lowering stroke of the horn when the measured pressing force transmitted from the pressing force indicator belongs to the set pressing force range. Or when the pressing force of the horn exceeds the set pressing force, for example, exceeds 200 kfg, the lowering stroke of the horn can be decreased to adjust the pressing force of the horn to be within the aforementioned set range.

[0061] On the one hand, as described above, the control unit 160 can control the range of the pressing force of the horn, and can also perform pinpoint control so that the pressing force of the horn becomes the optimum pressing force. In this case, the horn lowering stroke adjustment unit 130 can be repeatedly controlled until the measured pressing force of the horn becomes the optimum pressing force. For this purpose, the horn can be repeatedly raised and lowered until the measured pressing force of the horn becomes the optimum pressing force, and the pressing force can be repeatedly measured by the pressing force measurement sensor 115 to find the lowering stroke H of the horn indicating the optimum pressing force.

[0062] FIG. 9 shows that after the pressing force of the horn reaches the set pressing force range or the optimum pressing force, the anvils 110 for pressing force measurement and 140 for welding are repositioned so that the welded member W on the welding anvil is welded by the horn 120. Since the horn 120 descends by the lowering stroke H corresponding to the set pressing force range or the optimum pressing force to press the welded member W on the welding anvil for ultrasonic welding, weak welding of the welded member and excessive wear of the horn and the anvil can be prevented.

[0063] In addition, in this embodiment, since the control unit 160 automatically controls the horn lowering stroke adjustment unit 130 or the lowering stroke of the horn, there is an advantage that the pressing force of the horn can be adjusted more precisely and accurately.

[0064] (Third Embodiment) FIGS. 10 and 11 are side views and front views showing the configuration of an ultrasonic welding apparatus 100" according to still another embodiment of the present invention, and FIG. 12 is a perspective view showing a main part of the ultrasonic welding apparatus 100" of FIGS. 10 and 11.

[0065] This embodiment is characterized in that not only the automatic control of the horn lowering stroke adjustment is linked with the confirmation of the pressing force of the horn, but also the position change of the anvil for pressing force measurement and the welding anvil can be automatically performed.

[0066] Referring to FIGS. 10 to 12, the anvil 110 for pressure measurement and the anvil 140 for welding in this embodiment are arranged to be relatively movable with respect to the horn 120 at the lower part of the horn with a predetermined interval therebetween. In this embodiment, when the anvil 110 for pressure measurement and the anvil 140 for welding move relative to the horn, the positions of the anvil for pressure measurement and the anvil for welding with respect to the horn can be varied.

[0067] Specifically, this embodiment includes a movable plate 170 that can slide relative to the horn at the lower part of the horn 120. The anvil 110 for pressure measurement and the anvil 140 for welding are fixedly installed on the movable plate 170 with a predetermined interval therebetween. When the operation of adjusting the downward stroke of the horn by the control unit 160 is completed, the operator or according to the movement signal of the control unit, the movable plate 170 is slid relative to the horn. That is, due to the movement of the movable plate 170, the anvil 110 for pressure measurement and the anvil 140 for welding move horizontally simultaneously with respect to the horn. Along with this, the anvil 110 for welding will be located at the lower part of the horn. Thereafter, the horn can be lowered onto the anvil 140 for welding by a downward stroke corresponding to the set pressure or the optimum pressure, and the welded member W supported by the anvil for welding can be pressurized and ultrasonically welded. When the ultrasonic welding is completed, the movable plate 170 can be moved back to the original position to repeat the pressure measurement operation by the anvil 110 for pressure measurement.

[0068] Therefore, according to this embodiment, it is not necessary to disassemble the anvil 110 for pressure measurement and install the anvil 140 for welding each time when shifting to the welding process after measuring the pressure and adjusting the downward stroke of the horn. The control unit 160 can comprehensively control the pressure measurement, the adjustment of the downward stroke of the horn, and the movement of the anvil 110 for pressure measurement and the anvil 140 for welding. If necessary, the control unit 160 can be connected to the ultrasonic generator and the transducer to integrally control them together.

[0069] As described above, after adjusting the lowering stroke H of the horn by comparing the pressing force of the horn measured by the anvil 110 for measuring the pressing force with the set pressing force range or the optimum pressing force of the horn, the replacement of the anvil 110 for measuring the pressing force and the installation of the anvil 140 for welding can be manually performed, for example, by disassembling the fastening member of the fastening portion of the anvil for measuring the pressing force and coupling the fastening member of the fastening portion of the anvil for welding to a base or the like. However, this requires time and personnel and can reduce the automatic control efficiency of the control unit 160. In this embodiment, the present invention is made more suitable for mass production and equipment automation by enabling the replacement or position change of the anvil to be automatically performed, for example, by the control unit 160, in association with the lowering stroke of the horn.

[0070] The sliding movement of the movable plate 170 relative to the horn 120 can be performed by a linear movement mechanism in the generally known mechanical field. For example, as shown in FIGS. 10 and 12, a guide rail 151 is installed on the base 150, and a guide groove 171 is formed in the lower portion of the movable plate 170, so that the movable plate 170 can be slidably moved relative to the horn 120 and the base 150. Alternatively, conversely, a guide rail may be installed in the lower portion of the movable plate 170 and a guide groove may be formed on the base 150. Further, the movable plate 170 only needs to move relative to the horn and does not necessarily have to be installed on the base 150. However, in this embodiment, for the stability of the sliding operation, the movable plate 170 is installed on the base 150 on which a cylinder or the like is installed, and the movable plate is moved relative to the horn.

[0071] Before and after the movable plate 170 moves, a stopper 152 or a fixing member that restricts the moving distance of the movable plate 170 and stops the movable plate can be installed on the guide rail 151. FIGS. 11 and 12 show a state in which after the pressure measurement is performed by the anvil 110 for pressure measurement, the movable plate 170 moves and the welding anvil 140 is located below the horn, and the stopper 152 is fixed to the guide rail 151 and the movable plate 170 stops. When the stopper 152 is separated from the guide rail 151 and the welding anvil 140 is moved to the left with respect to the horn, the anvil 110 for pressure measurement can be positioned again below the horn. In this state, the stopper 152 can be coupled to the guide rail 151 on the base 150 to fix the anvil 110 for pressure measurement and the welding anvil 140 in position with respect to the horn 120.

[0072] In addition to the guide rail 151 and the guide groove 171, by installing a servo motor and a ball screw mechanism (not shown) on the movable plate 170, the movable plate 170 can be relatively moved with respect to the horn and the base. In this case, since the moving distance of the movable plate can be restricted by the rotation amount of the servo motor and the movable plate can be stopped, the above-described stopper is not necessarily required. However, it is preferable to install a stopper to securely fix the movable plate before and after the movement of the movable plate and perform welding without shaking with respect to the horn.

[0073] In this embodiment, the relative movement of the anvil 110 for pressure measurement and the welding anvil 140 with respect to the horn has been described. However, the horn 120 may be deformed to move relatively in the horizontal direction with respect to the anvil. Further, in this embodiment, it has been shown that the anvil 110 for pressure measurement and the welding anvil 140 move relatively in the horizontal direction crossing the extending direction of the horn. However, it may be deformed such that the movable plate 170 moves relatively below the horn 120 in a direction parallel to the extending direction of the horn 120. Needless to say, the moving direction of the anvil or the movable plate with respect to the horn can be appropriately changed in consideration of the extending direction of the horn, the arrangement direction of the anvil, and the like.

[0074] Hereinafter, each step of the ultrasonic welding method of the present invention will be described.

[0075] FIG. 13 is a flowchart showing the sequence of the ultrasonic welding method according to the present invention.

[0076] First, an anvil 110 for measuring the pressing force provided with a pressing force measurement sensor 115 is arranged below the horn 120 (step S10). The anvil 110 for measuring the pressing force can be installed by a fastening member C at a set position below the horn (a set position on the base 150). Alternatively, when a movable plate 170 that can slide relative to the horn is installed on the base 150, it can be fixedly installed on the movable plate 170 by a fastening member C. As shown in FIGS. 3 and 4, the anvil 110 for measuring the pressing force can be manufactured in a shape different from that of a normal welding anvil, and can be provided with an extended protruding portion 112 or the like so as to have a sufficient space for installing the pressing force measurement sensor 115.

[0077] Next, the horn 120 is lowered to press the anvil 110 for measuring the pressing force, and the pressing force of the horn is measured by the pressing force measurement sensor 115 (step S20). The pressing force measurement sensor 115 can be a load measurement sensor such as a load cell. Further, the pressing force measurement sensor is connected to a pressing force indicator 117 to digitize the pressing force of the horn and display it numerically in real time. The pressing force of this horn can be confirmed visually or transmitted to the control unit.

[0078] Thereafter, the measured pressing force of the horn 120 is compared with the set pressing force range, and the downward stroke of the horn is adjusted so that the pressing force of the horn is included in the set pressing force range (step S30).

[0079] The adjustment of the downward stroke of the horn can be performed, for example, by controlling the pneumatic or hydraulic pressure supplied to a pneumatic or hydraulic cylinder, or by controlling the amount of rotation of a servo motor connected to a linear movement mechanism such as a ball screw. The adjustment of the above stroke can be performed manually by an operator or automatically by the control unit 160.

[0080] When the measured pressing force does not belong to the set pressing force range or is different from the optimum pressing force, the above pressing force measurement and downward stroke adjustment operations can be repeated as necessary.

[0081] After the downward stroke H of the horn is adjusted, the position of the anvil 110 for pressing force measurement and the welding anvil 140 on which the member to be welded is placed and supported is changed (step S40). In this case, the position of the anvil can be manually changed or replaced, but this reduces efficiency. Therefore, as shown in FIGS. 11 and 12, the anvil 110 for pressing force measurement and the welding anvil 140 are fixedly installed in advance, and the anvil can be easily replaced by relatively moving the anvil with respect to the horn 120.

[0082] Finally, the horn 120 is lowered at the adjusted downward stroke H, and vibration is applied to ultrasonically weld the member to be welded W on the welding anvil (step S50).

[0083] In step S20, when the horn 120 presses the anvil for pressing force measurement, ultrasonic vibration is not applied to the horn. This makes it possible to more accurately measure the pressing force of the horn without the influence of ultrasonic waves.

[0084] In the S30 stage, the downward stroke of the horn 120 can be repeatedly adjusted until the measured pressing force of the horn 120 reaches the set optimum pressing force. After obtaining the downward stroke corresponding to the optimum pressing force by repeated adjustment, if the horn is lowered to the welding anvil 140 at that downward stroke to weld the member to be welded, welding can be performed with the optimum pressing force. As a result, for example, weak welding between the electrode tab and the electrode lead can be prevented. Also, since welding is performed with the optimum pressing force, problems such as excessive wear of the horn and the welding anvil or disconnection of the electrode tab or lead due to strong pressure can be prevented.

[0085] The above description merely exemplarily explains the technical idea of the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the drawings disclosed in the present invention are for explanation purposes rather than for limiting the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by such drawings. The protection scope of the present invention should be construed according to the following claims, and all technical ideas within the equivalent scope should be construed as being included in the scope of the present invention.

[0086] On the other hand, although terms indicating directions such as up, down, left, right, front, and back are used in this specification, such terms are merely for convenience of explanation and it is obvious that they can change depending on the position of the object and the position of the observer, etc.

Explanation of Reference Numerals

[0087] 100, 100´, 100″: Ultrasonic welding apparatus 110: Anvil for measuring pressing force 111: Body part 112: Extended protrusion 113: Installation groove 114: Fastening part 120: Horn 121: Expansion part 130: Horn stroke adjustment part (pneumatic cylinder) 131: Cylinder body 132: Cylinder rod 140: Welding anvil 141: Body part 142: Fastening part 150: Base 151: Guide rail 152: Stopper 160: Control unit 170: Movable plate 171: Guide groove G: Ultrasonic generator T: Transducer B: Booster C: Fastening member P: Support stand W: Welded member

Claims

1. An anvil for pressure measurement equipped with a pressure measurement sensor; A horn installed above the anvil for pressure measurement so as to be movable up and down, and pressurizing the anvil for pressure measurement when descending; A horn descent stroke adjustment unit capable of adjusting the descent stroke of the horn so that the pressure applied by the horn is within a set pressure range; and An ultrasonic welding apparatus including a welding anvil that is placed and supported with a weldment to be welded by the horn, and after the descent stroke of the horn is adjusted so as to be within the set pressure range, is repositioned with the anvil for pressure measurement and located below the horn.

2. The ultrasonic welding apparatus according to claim 1, further including a pressure indicator connected to the pressure measurement sensor and representing the pressure applied by the horn sensed by the pressure measurement sensor.

3. The ultrasonic welding apparatus according to claim 1, wherein the pressure measurement sensor is installed in an installation groove formed at the center of the upper surface of the anvil for pressure measurement.

4. The anvil for pressure measurement includes an extended protruding portion protruding from one or both sides of the upper part of the body, and the pressure measurement sensor is installed in the installation groove formed at the center of the upper surface of the extended protruding portion. The ultrasonic welding apparatus according to claim 3.

5. The ultrasonic welding apparatus according to claim 1, wherein when the horn pressurizes the anvil for pressure measurement, no ultrasonic vibration is applied to the horn.

6. The ultrasonic welding apparatus according to claim 1, further including a control unit that compares the measured pressure applied by the horn with a set pressure range, and controls the horn descent stroke adjustment unit so that the pressure applied by the horn is within the set pressure range.

7. The ultrasonic welding apparatus according to claim 6, wherein the control unit compares the measured pressure applied by the horn with an optimal set pressure, and repeatedly controls the horn descent stroke adjustment unit so that the pressure applied by the horn becomes the optimal pressure.

8. The horn descent stroke adjustment unit is a hydraulic or pneumatic cylinder, and the control unit controls the hydraulic or pneumatic pressure supplied to the hydraulic or pneumatic cylinder to adjust the descent stroke of the horn. The ultrasonic welding apparatus according to claim 6.

9. The horn lowering stroke adjustment unit is a linear movement mechanism that moves by a servo motor, and the control unit controls the rotation amount of the servo motor to adjust the lowering stroke of the horn. The ultrasonic welding apparatus according to claim 6.

10. The anvil for pressure measurement and the anvil for welding are installed at a predetermined interval and are relatively movable with respect to the horn below the horn. Moreover, when the anvil for pressure measurement and the anvil for welding move relative to the horn, the positions of the anvil for pressure measurement and the anvil for welding with respect to the horn are variable. The ultrasonic welding apparatus according to claim 1 or claim 6.

11. It further includes a movable plate that slides relative to the horn below the horn, and the anvil for pressure measurement and the anvil for welding are fixedly installed at a distance from each other. When the movable plate slides relative to the horn, the positions of the anvil for pressure measurement and the anvil for welding with respect to the horn are variable. The ultrasonic welding apparatus according to claim 10.

12. The member to be welded is a plurality of electrode tabs extending from the electrode assembly of the secondary battery, or the electrode tabs and electrode leads. The ultrasonic welding apparatus according to claim 1.

13. Placing an anvil for pressure measurement provided with a pressure measurement sensor below the horn; Lowering the horn to press the anvil for pressure measurement, and measuring the pressure of the horn by the pressure measurement sensor; Comparing the measured pressure of the horn with the set pressure range, and adjusting the lowering stroke of the horn so that the pressure of the horn is included in the set pressure range; After the lowering stroke of the horn is adjusted, changing the position of the anvil for pressure measurement and the anvil for welding on which the member to be welded is placed and supported so that the anvil for welding is positioned below the horn; and Lowering the horn with the adjusted lowering stroke to ultrasonically weld the member to be welded on the anvil for welding. An ultrasonic welding method including:

14. When the horn presses the anvil for pressure measurement, no ultrasonic vibration is applied to the horn. The ultrasonic welding method according to claim 13.

15. Repeatedly adjust the downward stroke of the horn until the measured pressing force of the horn reaches the set optimum pressing force, and lower the horn to the welding anvil with the downward stroke corresponding to the optimum pressing force to weld the member to be welded. The ultrasonic welding method according to claim 13 or claim 14.

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