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 the contents disclosed in the corresponding Korean patent application are incorporated herein by reference.

Background Art

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

[0008] The tab W1 derived from the electrode assembly is stacked vertically with the electrode lead W2 and positioned on the anvil 20 of the ultrasonic welding apparatus. Above the anvil 20 is a horn 10 that provides vibrations for ultrasonic bonding. The horn 10 descends over the workpieces, the tab W1 and lead W2, and applies vibrations while applying pressure to the workpieces, thereby ultrasonically welding the tab and lead.

[0009] During ultrasonic welding, the horn 10 applies pressure to the workpiece while welding, so the pressure applied by the horn 10 affects the welding quality. For example, if the pressure applied by the horn 10 is too weak during ultrasonic welding, a weak weld may occur where the tab W1 and lead W2 separate. Conversely, if the pressure applied by the horn 10 is too strong, problems may arise such as the tab or lead breaking, or the horn or anvil wearing out prematurely.

[0010] Therefore, when performing ultrasonic welding using a horn and anvil, it is important to maintain the horn's pressure within a set range or at the optimal pressure. However, conventionally, there has been no way to accurately check the horn's pressure. For example, even if a pressure sensor is installed on the anvil to measure the horn's pressure, ultrasonic vibrations are applied during welding, making it impossible to accurately measure the horn's pressure. Furthermore, since the horn's pressure changes slightly each time the workpiece is replaced or a worn horn or anvil is replaced, there is a technical challenge in that it is difficult to perform ultrasonic welding with uniform weld quality. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Korean Published Patent No. 10-2021-0037902 [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] The present invention was devised to solve the above-mentioned problems, and aims to provide an ultrasonic welding apparatus and ultrasonic welding method that can accurately measure the pressure applied to the horn and adjust the downward stroke of the horn so that the set pressure is achieved. [Means for solving the problem]

[0013] The ultrasonic welding apparatus according to the present invention includes: a pressure measuring anvil equipped with a pressure measuring sensor; a horn installed above the pressure measuring anvil so as to be movable up and down and pressurizing the pressure measuring anvil when it is lowered; a horn lowering stroke adjustment unit that can adjust the lowering stroke of the horn so that the pressurizing force of the horn falls within a set pressure range; and a welding anvil on which the member to be welded by the horn is placed and supported, and which is positioned below the horn after the lowering stroke of the horn has been adjusted so as to fall within the set pressure range, and is positioned differently from the pressure measuring anvil.

[0014] In a specific example, the ultrasonic welding apparatus of the present invention may further include a pressure indicator connected to the pressure measurement sensor to represent the pressure sensed by the pressure measurement sensor.

[0015] In a specific example, the pressure measurement sensor can be installed in a mounting groove formed in the center of the upper surface of the pressure measurement anvil.

[0016] In a more specific example, the pressure measuring anvil may have an extended projection protruding from one or both sides of the upper part of the body, and the pressure measuring sensor may be installed in a mounting groove formed in the center of the upper surface of the extended projection.

[0017] As a specific example, when the horn pressurizes the pressure measuring anvil, ultrasonic vibration does not necessarily have to be applied to the horn.

[0018] As one example, the control unit may further include a control unit that compares the measured pressure applied to the horn with a set pressure range and controls the horn's downward stroke adjustment unit so that the pressure applied to the horn falls within the set pressure range.

[0019] In a specific example, the control unit can compare the measured pressure applied to the horn with the set optimal pressure and repeatedly control the horn lowering stroke adjustment unit so that the pressure applied to the horn becomes the optimal pressure.

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

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

[0022] In another embodiment of the present invention, the pressure measuring anvil and the welding anvil are installed at a predetermined distance apart below the horn so as to be movable relative to the horn, and the positions of the pressure measuring anvil and the welding anvil relative to the horn can be varied by moving them relative 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 welded member may be a plurality of electrode tabs extending from the electrode assembly of the secondary battery, or the electrode tabs and electrode leads.

[0025] As another aspect of the present invention, an ultrasonic welding method 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 the 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 welded member 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 welded member 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 welded member.

Effect of the Invention

[0028] The present invention makes it possible to improve the quality of ultrasonic welding by checking the pressure applied to the horn before ultrasonic welding and adjusting it to a set pressure range or optimal pressure to prevent welding defects. [Brief explanation of the drawing]

[0029] [Figure 1] This is a schematic diagram illustrating the process of ultrasonic welding electrode tabs and electrode leads. [Figure 2] This is a schematic diagram showing the configuration of an ultrasonic welding apparatus according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of a pressure measuring anvil and a pressure indicator, which are components of the ultrasonic welding apparatus of the present invention. [Figure 4] These are a plan view and a side view of a pressure measuring anvil, which is a component of the ultrasonic welding apparatus of the present invention. [Figure 5] This is a perspective view of a welding anvil, which is a component of the ultrasonic welding apparatus of the present invention. [Figure 6] This is a schematic diagram showing the adjustment process for the horn descent stroke according to the present invention. [Figure 7] This is a schematic diagram showing that welding is performed according to one embodiment of the present invention. [Figure 8] This is a schematic diagram showing the configuration of an ultrasonic welding apparatus according to another embodiment of the present invention. [Figure 9] This is a schematic diagram showing the configuration of an ultrasonic welding apparatus according to another embodiment of the present invention. [Figure 10] A side view and a front view showing the configuration of an ultrasonic welding apparatus according to another embodiment of the present invention. [Figure 11] A side view and a front view showing the configuration of an ultrasonic welding apparatus according to another embodiment of the present invention. [Figure 12] Figures 10 and 11 are perspective views showing the main components of the ultrasonic welding apparatus. [Figure 13] This is a flowchart showing the sequence of steps in the ultrasonic welding method according to the present invention. [Modes for carrying out the invention]

[0030] The present invention will now be described in detail. Before that, however, terms and words used in this specification and in the claims should not be interpreted restrictively in their usual or dictionary sense, but rather should be interpreted in a sense and concept that is consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best describe their invention.

[0031] In this application, terms such as “includes” and “have” are intended to specify the existence of features, numbers, stages, actions, components, parts, or combinations thereof described in the specification, and should be understood not to preemptively exclude the possibility of the existence or addition of one or more other features, numbers, stages, actions, components, parts, or combinations thereof. Furthermore, when a part such as a layer, film, region, or plate is said to be “on top” of another part, this includes not only when it is “directly on top” of the other part, but also when there are other parts in between. Conversely, when a part such as a layer, film, region, or plate is said to be “below” another part, this includes not only when it is “directly below” the other part, but also when there are other parts in between. Furthermore, in this application, being “placed on top” may include being placed at the bottom as well as at the top.

[0032] On the other hand, in this application, "lengthwise direction" means the direction in which the electrode leads of the battery cell protrude.

[0033] The present invention will be described in detail below.

[0034] The ultrasonic welding apparatus of the present invention includes: a pressure measuring anvil equipped with a pressure measuring sensor; a horn mounted above the pressure measuring anvil so as to be movable up and down and pressurizing the pressure measuring anvil when lowered; a horn lowering stroke adjustment unit that can adjust the lowering stroke of the horn so that the pressurizing force of the horn falls within a set pressure range; and a welding anvil on which the member to be welded by the horn is placed and supported, and which is positioned below the horn after the lowering stroke of the horn has been adjusted so as to fall within the set pressure range, and is positioned differently from the pressure measuring anvil.

[0035] This invention provides a pressure measuring anvil capable of measuring the pressure of a horn, allowing for the pre-measurement of the horn's pressure, which is closely related to welding quality. Furthermore, it includes a horn lowering stroke adjustment unit that allows for adjusting the horn's lowering stroke so that the pressure measured by the pressure measuring anvil falls within a set pressure range, thereby setting the horn's pressure within the set pressure range. When the horn's lowering stroke is adjusted so that the horn's pressure falls within the set pressure range, the positions of the pressure measuring anvil and the welding anvil on which the workpiece is placed and supported are changed, and the workpiece on the welding anvil is welded with the adjusted horn lowering stroke. This prevents welding defects such as weak welds and also prevents rapid wear of the horn and anvil.

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

[0037] Referring to Figure 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 and measures the pressure transmitted from the horn 120. Specifically, the pressure measuring sensor 115 can be a load sensing sensor such as a load cell. A 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 pressure measuring sensor 115 is not greatly limited as long as it can display a numerical value of pressure, and various forms of load cells such as beam load cells and cylindrical load cells can be used.

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

[0039] As shown in Figure 3, the present invention may 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 as an electrical signal and displayed as a numerical value visible to the naked eye on the pressure display section 117a of the pressure indicator 117. The pressure indicator 117 is also equipped with a predetermined operation button 117b. Since such load cells and pressure indicators 117 are commonly known pressure measuring members or load measuring members, a detailed explanation is omitted in this specification. Although a load cell is used as an example of a pressure measuring sensor in this specification, it goes without saying that other suitable types of pressure measuring sensors capable of measuring the pressure or load of a horn can be used.

[0040] It is preferable to install the pressure measurement sensor 115 in the center of the upper surface of the pressure measurement anvil 110. In this 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 allows for the application of a set pressure range or the optimal pressure. Therefore, if the pressure measurement sensor 115 is installed on the side or bottom of the pressure measurement anvil 110, 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 pressure measurement anvil 110, which is directly pressurized by the horn. Similarly, if the pressure measurement sensor 115 is installed off-center on either side of the upper surface of the anvil, it cannot accurately reflect the applied pressure. Thus, the pressure measurement sensor 115 is installed in the center of the upper surface of the anvil. For this purpose, as shown in Figure 4, the pressure measurement anvil 110 is provided with an installation groove 113 for the installation of the pressure measurement sensor 115 in the center of its upper surface.

[0041] The pressure measuring anvil 110 described above can be the same shape and material as a normal welding anvil. However, if the size of the workpiece to be welded is small, the size of the welding anvil will also be small. In particular, the electrode tabs and electrode leads of secondary batteries are very small, so the size of the welding anvil used to weld them is also relatively small. In this case, if an anvil of the same size and shape as a welding anvil is used for pressure measuring, it will not be possible to secure sufficient space on the anvil to install the pressure measuring sensor. In order to secure space to install the pressure measuring sensor 115, a pressure measuring anvil 110 that has been processed to have a different shape from the welding anvil 140 can be used, as shown in Figures 3 and 4. The pressure measuring anvil 110 described above comprises a body portion 111, fastening portions 114 protruding from both sides of the body portion, and an extended projection portion 112 formed on the upper part of the body portion.

[0042] As shown in Figure 4, the extended protrusions 112 protrude from both sides of the upper part of the body 111, providing a larger mounting surface. However, the extended protrusions 112 may also protrude from one side of the upper part of the body. The direction, size, and shape of the extended protrusions 112 can be appropriately changed considering the size and shape of the sensor to be installed. An installation groove 113 is formed in the center of the upper surface 112A of the extended protrusions 112, and the pressure measuring sensor 115 can be installed in this installation groove 113. Fastening parts 114 are provided on both sides of the body 111 of the pressure measuring anvil 110, and fastening holes 114a are formed in the fastening parts for installing the pressure measuring anvil 110 on a support member such as a base. Therefore, the pressure measuring anvil 110 can be fixedly connected to a support member such as a base through the fastening holes 114a with fastening members C such as bolts.

[0043] Conventional welding anvils have irregularities on their surface to pressurize and press-fit the workpiece during ultrasonic vibration (see Figure 5), but the pressure measuring anvil 110 described above is not for welding, so no protrusions are formed on its upper surface.

[0044] Referring again to Figure 2, a horn 120 is installed above the pressure measuring anvil 110 so as to be able to move up and down. The horn 120 is for providing vibrations for ultrasonic welding to the joint portion of the member to be welded W, and the portion that contacts the member to be welded W may be provided with an uneven surface that can form an indentation mark on the member to be welded above in order to effectively transmit the vibrations. The horn 120 is also called a sonotrode and has an extended portion 121 at its tip that contacts the member to be welded. However, this shape of horn is just one example, and it goes without saying that other forms of horns capable of performing ultrasonic welding can be used. 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 is lowered. However, if necessary, the pressure of the horn can be increased by installing a separate pressurizing unit (not shown) above the horn 120. For example, the horn can be further pressurized by using a drive cylinder driven by a separate drive unit above the horn as the pressurizing unit.

[0045] The horn 120 is connected to an ultrasonic generator G that generates ultrasonic waves, a transducer T that converts ultrasonic waves into vibrations, and a booster B that amplifies the amplitude of the transducer. The ultrasonic generator G, transducer T, and booster B are known components commonly used in ultrasonic welding equipment, so a detailed explanation of them is omitted.

[0046] The horn 120 may be positioned above the pressure measuring anvil 110 so as to be able to move up and down, either independently or together with other ultrasonic welding components such as a booster. When the horn 120 descends toward the pressure measuring anvil 110 and pressurizes the pressure measuring sensor 115 (e.g., a load cell) on the pressure measuring anvil, the pressurizing force of the horn is measured. When the pressurizing force of the horn is measured by the pressure measuring sensor, ultrasonic vibration is not applied to the horn 120. This is because if ultrasonic vibration is applied, the pressurizing force of the horn 120 will vary even if the horn 120 descends with the same downward stroke, making it impossible to measure the pressurizing force accurately.

[0047] A horn lowering stroke adjustment unit 130 is provided to adjust the raising or lowering stroke of the horn 120. Known vertical movement mechanisms can be used as such a stroke adjustment unit. For example, a hydraulic or pneumatic cylinder can be installed at the bottom of the support base P that supports the horn 120, and hydraulic or pneumatic pressure can be supplied to the cylinder to raise or lower the horn. As an example of a pneumatic cylinder, a single-acting cylinder with one air intake port or a double-acting cylinder with air intake ports on both the inlet and outlet sides can be used. Alternatively, a linear movement mechanism connected to a servo motor, such as a ball screw and ball nut, can be used to raise or lower the horn. In this case, an LM guide rail or the like can be used to guide the movement of the linear movement mechanism as needed. Other vertical movement mechanisms or linear movement mechanisms commonly used in the art can also be used as the horn lowering stroke adjustment unit. In this embodiment, a pneumatic cylinder 130 comprising a cylinder body 131 and a cylinder rod 132 is introduced as the horn lowering stroke adjustment unit.

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

[0049] The pressure applied by the horn 120 can be expressed by the stroke over which the horn descends. That is, the more the horn 120 descends relative to the workpiece W, the greater the pressure applied by the horn to the workpiece W. Conversely, as the horn's downward stroke shortens, the pressure applied by the horn to the workpiece decreases. In other words, the pressure applied by the horn 120 can be expressed or converted by the horn's downward stroke, and the pressure applied by the horn can be adjusted by adjusting the downward stroke. The horn downward stroke adjustment unit 130, such as the aforementioned hydraulic or pneumatic cylinder, or a servo motor and a linear movement mechanism coupled thereto, can be adjusted so that the pressure applied by the horn 120 falls within a set pressure range. However, this requires prior measurement of the pressure applied by the horn. As mentioned above, the pressure applied by the horn 120 is variable during vibration, and the pressure applied by the horn may change depending on the type of workpiece W, or by replacing the workpiece, horn, or anvil. Therefore, as shown in Figure 6, the horn 120 is first lowered using the pressure measuring anvil 110 to check the (initial) pressure of the horn. If this pressure differs from the set pressure range, the horn's lowering stroke can be varied using the horn lowering stroke adjustment unit 130, and the pressure of the horn can be measured repeatedly. At this time, the pressure of the horn is displayed in real time by the pressure indicator 117, so the lowering stroke of the horn 120 can be adjusted while comparing whether the measured pressure falls within the set pressure range. For example, the operator can check the pressure value on the pressure indicator 117 and adjust the length of the cylinder rod 132's movement by adjusting the hydraulic or pneumatic pressure to adjust the horn's lowering stroke. Alternatively, the horn's lowering stroke can be adjusted by controlling the amount of movement of the linear movement mechanism by controlling the rotation amount of a servo motor (not shown).

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

[0051] The pneumatic cylinder 150 is mounted on the base 150 to stably support the horn 120. In Figure 2, the pressure measuring anvil 110 is shown mounted on the base 150 as well, but the pressure measuring anvil 110 may be mounted on a separate support member.

[0052] After the horn's downward stroke H is adjusted by the horn downward stroke adjustment unit 130 so that the downward stroke of the horn 120 falls within the set pressure range, the welding anvil 140 is provided, which is repositioned from the pressure measuring anvil 110.

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

[0054] Referring to Figure 5, the welding anvil 140 comprises a body portion 141 and fastening portions 142 on the left and right sides of the body portion, each having fastening holes 142a into which fastening members can be inserted. Furthermore, the upper surface 141A of the body portion 141 is provided with irregularities that can form press-fit marks on the bottom surface of the member to be welded. The illustrated form of the welding anvil is merely an example and is not necessarily limited to the above form of an anvil. Since the welding anvil is the part in which ultrasonic welding is actually carried out by the horn, the member to be welded is placed and supported on the upper part of the welding anvil. That is, as shown in Figure 1, for example, if the member to be welded W is an electrode tab W1 and electrode lead W2 extending from the electrode assembly of a secondary battery, the electrode tab and electrode lead are stacked and located on the welding anvil 140.

[0055] Referring to Figure 2(b), the welding anvil 140 is shown in a position swapped with the pressure measuring anvil 110 and installed below the horn 120. The position swapping or replacement of the pressure measuring anvil 110 and the welding anvil 140 can be performed manually by an operator. In this case, the fastening member C is separated from the fastening portion 114 of the pressure measuring anvil 110 and the pressure measuring anvil 110 is removed from the base 150, etc. Thereafter, the welding anvil 140 can be placed in the position where the pressure measuring anvil 110 was installed, and the fastening member C can be attached to the fastening portion 141 of the welding anvil 140 to install the welding anvil 140 below the horn. However, the position swapping of the pressure measuring anvil and the welding anvil may be performed automatically using a separate moving member, as will be described later.

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

[0057] Figure 7 shows the state in which the welding anvil 140 is positioned on the base 150 after the downward stroke H of the horn has been adjusted so that it falls within the set pressure range, and the pressure measuring anvil 110 has been repositioned. In this case, the pressure applied by 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 applied force falls within the set pressure range by comparing it with the set pressure. Therefore, the horn 120 will descend to the workpiece on the welding anvil 140 by a downward stroke H corresponding to the set pressure. Subsequently, as shown in Figure 7, the ultrasonic vibrations transmitted from the ultrasonic generator G - transducer T - booster B allow the horn 120 to ultrasonically weld the workpiece W on the welding anvil with the set pressure.

[0058] (Second Embodiment) Figures 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 Figures 8 and 9, the ultrasonic welding apparatus 100' of this embodiment may further include a control unit 160 that compares the measured pressure of the horn with a set pressure range and controls the horn lowering stroke adjustment unit 130 so that the pressure of the horn falls within the set pressure range.

[0060] In other words, this embodiment includes a control unit 160 that automatically controls the horn lowering stroke adjustment in conjunction with the confirmation of the pressure applied to the horn 120. As shown in Figure 8, the control unit 160 is connected to the pneumatic cylinder of the horn lowering stroke adjustment unit 130, allowing the horn 120 to be automatically lowered from the pressure measurement stage. When the control unit 160 operates the horn lowering stroke adjustment unit 130 and the horn lowers onto the pressure measurement anvil 110, the pressure applied to the horn measured by the pressure measurement sensor 115 is displayed on the pressure indicator 117, and the control unit 160 can receive this pressure data. The control unit 160 also compares the measured pressure applied to the horn 120 with a set pressure range, and if the measured pressure applied to the horn falls outside the set pressure range, it can adjust the horn lowering stroke adjustment unit 130. For example, if the set pressure range for the electrode tab and electrode lead is 150-200 kgfg, and the measured pressure is less than 150 kgf, the control unit 160 controls the hydraulic / pneumatic pressure or increases the rotation amount of the servo motor to increase the downward stroke of the horn until the pressure on the horn becomes 150 kgf or more. At this time, the pressure measurement sensor 115 (load cell) continuously measures the pressure on the horn as the downward stroke increases, and this pressure can be displayed on the pressure indicator display unit 117a. The control unit 160 can save the downward stroke of the horn when the measured pressure transmitted from the pressure indicator falls within the set pressure range. Alternatively, if the pressure on the horn exceeds the set pressure, for example, if it exceeds 200 kgfg, the downward stroke of the horn can be reduced to adjust the pressure on the horn so that it falls within the aforementioned set range.

[0061] On the other hand, while the control unit 160 can control the range of pressure applied to the horn as described above, it can also perform pinpoint control to ensure that the pressure applied to the horn is optimal. In this case, the horn lowering stroke adjustment unit 130 can be repeatedly controlled until the measured pressure applied to the horn becomes the optimal pressure. To achieve this, the horn can be repeatedly raised and lowered until the measured pressure applied to the horn becomes the optimal pressure, and the pressure measurement sensor 115 can be repeatedly measured to find the horn lowering stroke H that indicates the optimal pressure.

[0062] Figure 9 shows that after the horn's pressure reaches the set pressure range or the optimal pressure, the pressure measuring anvil 110 and the welding anvil 140 are repositioned so that the workpiece W on the welding anvil is welded by the horn 120. The horn 120 descends by a downward stroke H corresponding to the set pressure range or the optimal pressure, applying pressure to the workpiece W on the welding anvil and performing ultrasonic welding, thus preventing weak welding of the workpiece and excessive wear of the horn and anvil.

[0063] Furthermore, this embodiment has the advantage that the horn's downward stroke adjustment unit 130 or the downward stroke of the horn can be adjusted more precisely and accurately because the control unit 160 automatically controls the downward stroke of the horn.

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

[0065] This embodiment is characterized by its ability to automatically control the horn's downward stroke adjustment in conjunction with the confirmation of the horn's applied pressure, as well as to automatically change the positions of the pressure measuring anvil and the welding anvil.

[0066] Referring to Figures 10 to 12, the pressure measuring anvil 110 and the welding anvil 140 in this embodiment are positioned at a predetermined distance from each other at the lower part of the horn 120 so as to be movable relative to the horn. In this embodiment, the positions of the pressure measuring anvil 110 and the welding anvil 140 relative to the horn can be varied by moving them relative to the horn.

[0067] Specifically, this embodiment includes a movable plate 170 that can slide relative to the horn 120 at its lower position. A pressure measuring anvil 110 and a welding anvil 140 are fixedly installed on the movable plate 170 at predetermined intervals. When the control unit 160 has finished adjusting the horn's lowering stroke, the operator or the control unit's movement signal causes the movable plate 170 to slide relative to the horn. That is, the movement of the movable plate 170 causes the pressure measuring anvil 110 and the welding anvil 140 to move simultaneously horizontally relative to the horn, and as a result, the welding anvil 110 is positioned below the horn. Thereafter, the horn is lowered onto the welding anvil 140 by a lowering stroke corresponding to the set pressure or optimal pressure, and the workpiece W supported by the welding anvil can be pressurized and ultrasonically welded. Once ultrasonic welding is complete, the movable plate 170 can be moved back to its original position, and the pressure measurement operation using the pressure measuring anvil 110 can be repeated.

[0068] Therefore, according to this embodiment, there is no need to disassemble the pressure measuring anvil 110 and set up the welding anvil 140 each time the process transitions from pressure measurement and horn descent stroke adjustment to the welding process. The control unit 160 can comprehensively control pressure measurement, horn descent stroke adjustment, and the movement of the pressure measuring anvil 110 and the welding anvil 140. If necessary, the control unit 160 can also be connected to the ultrasonic generator and transducer and their components can be integrated and controlled together.

[0069] As described above, after adjusting the horn's downward stroke H by comparing the pressure of the horn measured by the pressure measuring anvil 110 with the set pressure range or optimal pressure of the horn, the replacement of the pressure measuring anvil 110 and the installation of the welding anvil 140 can be done manually, for example, by disassembling the fastening members of the pressure measuring anvil's fastening section and connecting the fastening members of the welding anvil's fastening section to a base or the like. However, this requires time and manpower and can reduce the automatic control efficiency of the control unit 160. In this embodiment, the replacement or repositioning of the anvil in conjunction with the downward stroke of the horn can also be performed automatically by the control unit 160, for example, thereby making the present invention even more suitable for mass production and equipment automation.

[0070] The sliding movement of the movable plate 170 relative to the horn 120 can be performed by a linear motion mechanism commonly known in the mechanical field. For example, as shown in Figures 10 and 12, a guide rail 151 can be installed on the base 150, and a guide groove 171 can be formed on the lower part of the movable plate 170, allowing the movable plate 170 to slide relative to the horn 120 and the base 150. Alternatively, the opposite may be true: a guide rail can be installed on the lower part of the movable plate 170, and a guide groove can be formed on the base 150. Furthermore, 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, which is equipped with a cylinder or the like, and the movable plate is moved relative to the horn.

[0071] Before and after the movement of the movable plate 170, a stopper 152 or fixing member can be installed on the guide rail 151 to limit the movement distance of the movable plate 170 and stop the movable plate. Figures 11 and 12 show the state in which, after the pressure measurement by the pressure measuring anvil 110, the movable plate 170 has moved and the welding anvil 140 is positioned below the horn, and the stopper 152 is fixed to the guide rail 151, stopping the movable plate 170. By separating the stopper 152 from the guide rail 151 and moving the welding anvil 140 to the left relative to the horn, the pressure measuring anvil 110 can be positioned below the horn again. In this state, the stopper 152 can be connected to the guide rail 151 on the base 150, and the pressure measuring anvil 110 and the welding anvil 140 can be fixed in position relative to the horn 120.

[0072] By installing a servo motor and a ball screw mechanism (not shown) on the movable plate 170 in addition to the guide rail 151 and guide groove 171, the movable plate 170 can be moved relative to the horn and base. In this case, the movement distance of the movable plate can be limited by the amount of rotation of the servo motor and the movable plate can be stopped, so the aforementioned stopper is not necessarily required. However, it is preferable to install a stopper to securely fix the movable plate before and after its movement and to perform welding without it shaking relative to the horn.

[0073] In this embodiment, the pressure measuring anvil 110 and the welding anvil 140 are described as being moved relative to the horn, but the horn 120 may be deformed to be moved horizontally relative to the anvils. Also, in this embodiment, the pressure measuring anvil 110 and the welding anvil 140 are shown to be moved horizontally across the extension direction of the horn, but the movable plate 170 may be deformed to be moved relative to the lower part of the horn 120 in a direction parallel to the extension direction of the horn 120. Needless to say, the direction of movement of the anvil or movable plate relative to the horn can be appropriately changed considering the extension direction of the horn, the arrangement direction of the anvil, etc.

[0074] The following describes each step of the ultrasonic welding method of the present invention.

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

[0076] First, a pressure measuring anvil 110 equipped with a pressure measuring sensor 115 is placed at the bottom of the horn 120 (S10 stage). The pressure measuring anvil 110 can be installed at a set position at the bottom of the horn (a set position on the base 150) by fastening members C. Alternatively, if a movable plate 170 that can slide relative to the horn is installed on the base 150, the anvil 110 can be fixedly installed to the movable plate 170 by fastening members C. As shown in Figures 3 and 4, the pressure measuring anvil 110 can be manufactured in a shape different from a normal welding anvil, and may be equipped with an extended projection 112, etc., to provide sufficient space for installing the pressure measuring sensor 115.

[0077] Next, the horn 120 is lowered to pressurize the pressure measuring anvil 110, and the pressure of the horn is measured by the pressure measuring sensor 115 (S20 stage). The pressure measuring sensor 115 may be a load measuring sensor such as a load cell. The pressure measuring sensor is also connected to a pressure indicator 117 so that the pressure of the horn can be digitized and displayed numerically in real time. This pressure of the horn can be confirmed visually or transmitted to the control unit.

[0078] Subsequently, the measured pressure applied to the horn 120 is compared with the set pressure range, and the downward stroke of the horn is adjusted (S30 steps) so that the pressure applied to the horn falls within the set pressure range.

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

[0080] If the measured pressure does not fall within the set pressure range or differs from the optimal pressure, the above pressure measurement and downward stroke adjustment operations can be repeated as needed.

[0081] After the downward stroke H of the horn is adjusted, the pressure measuring anvil 110 and the welding anvil 140 on which the member to be welded is placed and supported are repositioned (S40 step). In this case, the position of the anvils can be changed or replaced manually, but this is inefficient. Therefore, as shown in Figures 11 and 12, the pressure measuring anvil 110 and the welding anvil 140 are fixed in place beforehand, and the anvils can be easily replaced by moving them relative to the horn 120.

[0082] Finally, the horn 120 is lowered with the adjusted downward stroke H, and vibration is applied to ultrasonically weld the workpiece W on the welding anvil (S50 stage).

[0083] In stage S20, when the horn 120 pressurizes the pressure measuring anvil, ultrasonic vibration is not applied to the horn. This allows for more accurate measurement of the pressurizing force of the horn without the influence of ultrasound.

[0084] In step S30, the downward stroke of the horn 120 can be repeatedly adjusted until the measured pressure of the horn reaches the set optimal pressure. After determining the downward stroke corresponding to the optimal pressure through repeated adjustment, the horn is lowered to the welding anvil 140 with that downward stroke and the workpiece is welded, thereby welding with the optimal pressure. This prevents, for example, weak welding between the electrode tab and the electrode lead. Furthermore, because welding is performed with the optimal pressure, problems such as excessive wear of the horn and welding anvil, and breakage of the electrode tab or lead due to strong pressure can be prevented.

[0085] The above description is merely illustrative of the technical concept of the present invention, and a person with ordinary skill in the art to which the present invention belongs will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the drawings disclosed herein are for illustrative purposes only, not to limit the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such drawings. The scope of protection of the present invention should be interpreted by the following claims, and all technical concepts within an equivalent scope should be interpreted as being included within the scope of the present invention.

[0086] On the other hand, while terms indicating direction such as up, down, left, right, front, and back are used in this specification, these terms are merely for the convenience of explanation, and it is self-evident that they can change depending on the position of the object in question, the observer's position, and so on. The following items will also be disclosed. [Item 1] An anvil for measuring pressure, equipped with a pressure measurement sensor; A horn is installed above the pressure measuring anvil so as to be movable up and down, and pressurizes the pressure measuring anvil when it is lowered; A horn downward stroke adjustment unit that can adjust the downward stroke of the horn so that the pressure applied to the horn falls within a set pressure range; and An ultrasonic welding apparatus comprising a welding anvil repositioned and located below the horn, wherein a workpiece to be welded is placed and supported by the horn, and the downward stroke of the horn is adjusted so that it falls within the set pressure range. [Item 2] The ultrasonic welding apparatus of item 1, further comprising a pressure indicator connected to the pressure measuring sensor and representing the pressure of the horn as sensed by the pressure measuring sensor. [Item 3] The ultrasonic welding apparatus of item 1, wherein the pressure measuring sensor is installed in a mounting groove formed in the center of the upper surface of the pressure measuring anvil. [Item 4] The ultrasonic welding apparatus of item 3, wherein the pressure measuring anvil comprises an extended projection protruding from one or both sides of the upper part of the body, and the pressure measuring sensor is installed in the mounting groove formed in the center of the upper surface of the extended projection. [Item 5] The ultrasonic welding apparatus according to item 1, wherein when the horn pressurizes the pressure measuring anvil, ultrasonic vibration is not applied to the horn. [Item 6] The ultrasonic welding apparatus of item 1, further comprising a control unit that compares the measured pressure of the horn with a set pressure range and controls the horn lowering stroke adjustment unit so that the pressure of the horn falls within the set pressure range. [Item 7] The ultrasonic welding apparatus of item 6, wherein the control unit compares the measured pressure applied to the horn with a set optimal pressure and repeatedly controls the horn lowering stroke adjustment unit so that the pressure applied to the horn becomes the optimal pressure. [Item 8] The ultrasonic welding apparatus of item 6, wherein the horn lowering 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 horn lowering stroke. [Item 9] The ultrasonic welding apparatus of item 6, wherein the horn lowering stroke adjustment unit is a linear movement mechanism moved by a servo motor, and the control unit controls the amount of rotation of the servo motor to adjust the lowering stroke of the horn. [Item 10] The pressure measuring anvil and the welding anvil are installed at a predetermined distance apart below the horn and are movable relative to the horn. The ultrasonic welding apparatus of item 1 or item 6, wherein the position of the pressure measuring anvil and the welding anvil relative to the horn is varied by the relative movement of the pressure measuring anvil and the welding anvil relative to the horn. [Item 11] The invention further includes a movable plate that slides relative to the horn at the lower part of the horn, and on which the pressure measuring anvil and the welding anvil are fixedly installed at a distance from each other. The ultrasonic welding apparatus of item 10, wherein the position of the pressure measuring anvil and the welding anvil relative to the horn is varied by the sliding movement of the movable plate relative to the horn. [Item 12] The ultrasonic welding apparatus according to item 1, wherein the member to be welded is a plurality of electrode tabs extending from an electrode assembly of a secondary battery, or the electrode tabs and electrode leads. [Item 13] The step of positioning a pressure measuring anvil, equipped with a pressure measuring sensor, at the bottom of the horn; A step of lowering the horn to pressurize the pressure measuring anvil, and measuring the pressure of the horn using the pressure measuring sensor; A step of comparing the measured pressure of the horn with a set pressure range and adjusting the downward stroke of the horn so that the pressure of the horn falls within the set pressure range; After the downward stroke of the horn has been adjusted, the steps of changing the position of the welding anvil on which the pressure measuring anvil and the member to be welded are placed and supported, so that the welding anvil is positioned below the horn; and An ultrasonic welding method comprising the step of ultrasonically welding the workpiece on the welding anvil by lowering the horn with the adjusted downward stroke. [Item 14] The ultrasonic welding method of item 13, wherein ultrasonic vibration is not applied to the horn when the horn pressurizes the pressure measuring anvil. [Item 15] The ultrasonic welding method of item 13 or item 14, comprising repeatedly adjusting the downward stroke of the horn until the measured pressure of the horn becomes the set optimal pressure, and then lowering the horn onto the welding anvil with the downward stroke corresponding to the optimal pressure to weld the member to be welded. [Explanation of Symbols]

[0087] 100, 100', 100″: Ultrasonic welding equipment 110: Anvil for measuring applied pressure 111: Torso 112: Expanded protrusion 113: Installation groove 114: Fastening section 120: Horn 121: Expansion section 130: Horn stroke adjustment mechanism (pneumatic cylinder) 131: Cylinder body 132: Cylinder rod 140: Welding Anvil 141: Torso 142: Fastening section 150: Bass 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: Member to be welded

Claims

1. An anvil for measuring pressure, equipped with a pressure measurement sensor; A horn is installed above the pressure measuring anvil so as to be movable up and down, and pressurizes the pressure measuring anvil when it is lowered; A horn descent stroke adjustment unit that can adjust the descent stroke of the horn so that the pressurizing force of the horn falls within a set pressurizing force range; and An ultrasonic welding apparatus comprising a horn on which a workpiece to be welded is placed and supported, and after the downward stroke of the horn is adjusted so that it falls within the set pressure range, the pressure measuring anvil and the welding anvil are positioned below the horn such that only one of them is positioned below the horn at a time.

2. The ultrasonic welding apparatus according to claim 1, further comprising a pressure indicator connected to the pressure measuring sensor and representing the pressure of the horn as sensed by the pressure measuring sensor.

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

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

5. The ultrasonic welding apparatus according to claim 1, wherein when the horn pressurizes the pressure measuring anvil, ultrasonic vibration is not applied to the horn.

6. The ultrasonic welding apparatus according to claim 1, further comprising a control unit that compares the measured pressure of the horn with a set pressure range and controls the horn lowering stroke adjustment unit so that the pressure of the horn falls within the set pressure range.

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

8. The ultrasonic welding apparatus according to claim 6, wherein the horn lowering stroke adjustment unit is a hydraulic or pneumatic cylinder, and the control unit adjusts the horn lowering stroke by controlling the hydraulic or pneumatic pressure supplied to the hydraulic or pneumatic cylinder.

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

10. The pressure measuring anvil and the welding anvil are installed at a predetermined distance apart below the horn and are movable relative to the horn. Furthermore, the ultrasonic welding apparatus according to claim 1 or claim 6, wherein the positions of the pressure measuring anvil and the welding anvil relative to the horn are varied by the relative movement of the pressure measuring anvil and the welding anvil relative to the horn.

11. The invention further includes a movable plate that slides relative to the horn at the lower part of the horn, and on which the pressure measuring anvil and the welding anvil are fixedly installed at a distance from each other. The ultrasonic welding apparatus according to claim 10, wherein the movable plate slides relative to the horn, thereby varying the positions of the pressure measuring anvil and the welding anvil relative to the horn.

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

13. The step of positioning a pressure measuring anvil equipped with a pressure measuring sensor at the bottom of the horn; A step of lowering the horn to pressurize the pressure measuring anvil and measuring the pressure of the horn using the pressure measuring sensor; A step of comparing the measured pressure of the horn with a set pressure range and adjusting the downward stroke of the horn so that the pressure of the horn falls within the set pressure range; After the downward stroke of the horn is adjusted, the positions of the pressure measuring anvil and the welding anvil on which the member to be welded is placed and supported are changed so that the welding anvil is positioned below the horn, and the step of having only one of the pressure measuring anvil and the welding anvil positioned below the horn at the same time; and An ultrasonic welding method comprising the step of ultrasonically welding the workpiece on the welding anvil by lowering the horn with the adjusted downward stroke.

14. The ultrasonic welding method according to claim 13, wherein when the horn pressurizes the pressure measuring anvil, ultrasonic vibration is not applied to the horn.

15. The ultrasonic welding method according to claim 13 or claim 14, wherein the downward stroke of the horn is repeatedly adjusted until the measured pressure of the horn becomes the set optimal pressure, and the horn is lowered onto the welding anvil with the downward stroke corresponding to the optimal pressure to weld the member to be welded.