Self-leveling stack assembly with forward-throwing uniform amplitude ultrasonic welding horn

Abstract

The ultrasonic welding machine (10) includes a booster (50) and a stack assembly (34) including an ultrasonic horn (14). The stack assembly is self-leveling and rotatable. The ultrasonic horn is annular and attached to the booster. The booster has a threaded cavity, and a threaded bolt (52) that passes through the annular ultrasonic horn is threaded into the booster's threaded cavity. The horn has a shank (35) that can be attached to a source of high-frequency ultrasonic vibrations and a switch (37). The switch has a height and a width, and the height is tapered to have a cross-sectional area smaller than that of the shank. The switch is attached to an intermediate holder (31) and has a cross-sectional area smaller than that of the switch. The intermediate holder has a recess on its concave surface. The intermediate holder supports a rectangular welding tip (33) that has a cross-sectional area larger than that of the intermediate holder.

Description

[Technical Field]

[0001] This application is a continuation-in-part application related to U.S. Provisional Patent Application No. 63 / 064,423 and U.S. Provisional Patent Application No. 63 / 183,204, filed August 12, 2020 and May 3, 2021, respectively.

[0002] This disclosure relates to high-frequency ultrasonic welding, and in particular to a novel, specially designed horn. The use of high-frequency ultrasonic vibrations to weld materials has been known since the 1960s. Ultrasonic welding machines do not heat the materials, but rather create friction by subjecting the materials to ultrasonic vibrations, which creates the weld. Ultrasonic welding has proven to be an effective method for joining both plastics and metals. Furthermore, it has been applied in many industries, from toy manufacturing to the automotive and aviation industries. Ultrasonic welding is widely used due to its ease of welding and low cost. Ultrasonic welding is also ideal for joining small parts.

[0003] Ultrasonic welding is an alternative to arc welding, heat welding and soldering, and does not require consumables such as solder, flux or tempering materials, nor does it require cooling water or high energy consumption.An added benefit of ultrasonic welding is that minimal heat is generated during the welding process, minimizing damage to components.

[0004] Ultrasonic metal welding is used to join similar or dissimilar non-ferrous metals, such as those used in electrical components and pipe sealing. The parts to be ultrasonically welded are held together under pressure between an ultrasonic horn and anvil. Ultrasonic vibrations at frequencies of approximately 20 kHz to 40 kHz are applied, and the vibrations of the horn cause the parts to rub against each other, creating shear forces that remove surface inclusions and expose bare metal areas.

[0005] The intense frictional forces generated by simultaneously applying pressure to weld two components breaks down the oxide film on the metal substrate. Instead of melting the materials, the metals are welded through solid-state welding. Ultrasonic vibrations create shear and deformation of surface roughness, which disperses oxides and impurities present in the materials, allowing for metal-to-metal contact and bonding of the adjoining surfaces. This process creates sufficient intimate contact between the two materials to create an atomic-level bond. The atomic makeup of the materials combines to create a solid-state bond with a strong molecular surface, no impurities, and low electrical resistance. The relatively small temperature rise caused by friction is well below the melting point and does not play a significant role in the welding process.

[0006] Ultrasonic welding is performed on plastics and metals through different processes. When applied to plastics, the friction generated by the ultrasonic vibrations is sufficient to melt the materials at the joint, and after cooling, the weld is complete. Ultrasonic welding typically requires very short welding times, typically between 200 and 400 milliseconds. For a more general discussion of ultrasonic welding, see "New Developments in Advanced Welding" edited by Nasir Ahmad (2005).

[0007] The basic components of an ultrasonic welding system are a press, anvil, ultrasonic stack assembly, ultrasonic generator or power supply, and electrical controller. The work pieces to be welded are placed between the press and anvil, and the press applies pressure to the work pieces. The anvil directs ultrasonic vibrations to the material surface. The nest or anvil on which the work pieces (parts) rest allows the high frequency vibrations generated by the stack assembly to be directed to the interface of the weld substrate.

[0008] An ultrasonic stack assembly typically consists of a transducer, a booster, and a sonotrode or "horn." The transducer converts electrical energy into mechanical vibrations. The booster modifies the amplitude of the vibrations. The sonotrode applies the mechanical vibrations to the parts to be welded. These three components are typically made to resonate at the same ultrasonic frequency (typically 20 kHz, 35 kHz, or 40 kHz). These stack assembly components are connected to an electric ultrasonic generator, which sends a high-power AC signal to the stack assembly to match its resonant frequency.

[0009] A user inputs commands into the system via a controller that controls press movement and activates the stack assembly power supply, which sends an electrical signal to the ultrasonic stack assembly to perform the weld. A transducer portion of the stack assembly converts the electrical signal into mechanical vibrations, utilizing a voltage booster to modify the vibration amplitude. A horn transmits the vibrations to the work piece. The welding horn typically consists of a handle attached to a welding tip.

[0010] The quality and success of ultrasonic welding depends on many factors, including signal amplitude, weld time, weld pressure, weld speed, hold time, and hold pressure. The appropriate values ​​for each of these factors depend on the type of material being welded and can vary greatly from material to material. In previous industrial practice, the only variables that could be effectively controlled were amplitude, force, and weld time or duration. Amplitude was controlled through a combination of frequency selection, horn and booster design, and modification of the electrical input to the transducer.

[0011] User control of the variables and the ultrasonic welding process is key to producing consistently effective welds. Better process control generally leads to improved weld quality, and therefore improved weld consistency and repeatability. In industry, welding is used to manufacture products, and when the weld quality of individual products is inspected, the typical error is between 2% and 4%. [Prior art documents] [Patent documents]

[0012] [Non-Patent Document 1] "New Developments in Advanced Welding," edited by Nasir Ahmad, 2005 Summary of the Invention [Problem to be solved by the invention]

[0013] Thin lithium-ion batteries (replacing copper and aluminum plies) are widely used in electric vehicles, such as cars and trucks. To provide longer battery life and / or more power to electric vehicles, thin batteries have grown in width and size by incorporating multiple layers. This increased battery size poses challenges for ultrasonic welding systems. Conventional horns, in particular, have difficulty achieving uniform welding across the entire width of thin batteries. The thin plies can easily bend at their corners, resulting in a "dog-eared" condition during pre-welding processing, primarily at the corners. As a result, the dog-eared plies are not welded across their entire width, resulting in a lack of electrical conductivity in the completed battery. The present invention proposes the detection of such bends. [Means for solving the problem]

[0014] The ultrasonic welding machine (10) includes a booster (50) and a stack assembly (34) including an ultrasonic horn (14). The stack assembly is self-leveling and rotatable. The ultrasonic horn has an annular shape and is attached to the booster. The booster has a threaded cavity, and a threaded bolt (52) that passes through the annular ultrasonic horn threadably engages with the booster's threaded cavity.

[0015] The high-frequency ultrasonic welding horn (14) includes a handle (36) consisting of a shaft (35) that can be attached to a source of high-frequency ultrasonic vibrations, and a switch (37) having a height and width. The cross-sectional area of ​​the switch is smaller than that of the shaft due to its tapered height. The switch is attached to an intermediate holder (31) having a height and width and a cross-sectional area smaller than that of the switch. The intermediate holder has a constant height and a concave recess on its side. The intermediate holder supports a rectangular welding tip (33), the cross-sectional area of ​​which is larger than that of the intermediate holder. The inverted concave areas allow for a more uniform weld across the entire welding edge of the horn.

[0016] A method for detecting foil fold edges in stacked foils includes welding the stacked foils with an ultrasonic welder (10) having a booster (50) and a stack assembly (34) with an ultrasonic horn (14), where the stack assembly is self-leveling and rotatable.

[0017] 8, the horn assembly 14 fits head-on into the rotating stack assembly 34 using threaded bolts 52 and is positioned by the threaded bolts 52 against the booster headstock 50. In the field or at the factory, this assembly method allows for easy removal and replacement by rotating the horn assembly 14, as it can be easily removed by simply removing the threaded bolts 52. More importantly, this assembly method allows for the horn to be replaced without having to disassemble the ultrasonic welder 10 or other components.

[0018] For a better understanding of the nature and advantages of the present methods and processes, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0019] [Figure 1]FIG. 1 is an isometric view of a high frequency ultrasonic self-leveling welding system of the present disclosure. [Figure 2] FIG. 2 is a side view of the welding head showing the horn welding the edges of the stacked battery plies. [Figure 3] FIG. 3 is a front view of the high frequency ultrasonic self-leveling welding system with the front cover removed. [Figure 4] Figure 4 is an enlarged front view of the welding horn. Figure 4A is a perspective view of the encoder. Encoder bracket 25 is mounted on the backside and includes encoder sensor 27 that reads the position of encoder strip 29 in the slot of booster mounting ring 40. [Figure 5] FIG. 5 is an isometric view of the welding assembly. [Figure 6] FIG. 6 is an isometric view of a self-centering die stack. [Figure 7] FIG. 7 is a front view of the horn. [Figure 8] Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7. Figure 8A is an enlarged view of the vibration absorbing O-ring and the installation of the booster 50. [Figure 9] FIG. 9 is an isometric close-up view of the components of the stack assembly. [Figure 10] FIG. 10 is an isometric view of the laminated battery plies, showing one layer of the laminate with a corner folded (folded). [Figure 11] FIG. 11 is an enlarged front view of the welding assembly in position for welding. [Figure 12] FIG. 12 is a side elevational view of the novel horn of the present disclosure shown in FIG. [Figure 13] 13 is a front view of the novel horn of the present disclosure shown in FIG. 3. FIG. 13A is a cross-sectional view taken along line 13A-13A of FIG. [Figure 14] FIG. 14 is a top / bottom view of the novel horn of the present disclosure shown in FIG. [Figure 15] FIG. 15 is an isometric view of a novel horn of the present disclosure having a notch, niche, or concave surface on the side. [Figure 16] FIG. 16 is an isometric view of a prior art horn without side cutouts or niches. [Figure 17] FIG. 17 illustrates experimental results (gauge measurements) of amplitude for examples of operating the novel horn of one embodiment at various positions on the welding horn and at various power levels of the welding unit. [Figure 18] FIG. 18 illustrates experimental results (gauge measurements) of amplitude for an embodiment of a prior art horn operated at various positions on the welding horn and with varying power levels of the welding unit. [Figure 19] FIG. 19 illustrates experimental amplitude results (laser measurements) for examples of operating the novel horn of one embodiment at various positions on the welding horn and at various power levels of the welding unit. [Figure 20] FIG. 20 illustrates experimental amplitude results (laser measurements) for an embodiment of a prior art horn operated at various positions on the welding horn and with varying power levels of the welding unit. [Figure 21] FIG. 21 is an isometric view of the novel horn in one embodiment, showing numerically labeled points across the horn and alphabetically labeled points along the length of the horn. [Figure 22] FIG. 22 illustrates experimental results for an embodiment where the novel horn of FIG. 12 is operated at 100% power output of the welding unit. [Figure 23] FIG. 23 is an isometric view of a prior art horn showing numerically labeled points across the horn and alphabetically labeled points along the length of the horn. [Figure 24]Figure 24 illustrates experimental results for an example where the welding unit was operated at 100% power and the prior art horn of Figure 14 was operated. The figures are described in detail below in connection with the example. DETAILED DESCRIPTION OF THE INVENTION

[0020] The growing popularity of electric vehicles has driven battery development, increasing the need for welding the edges of extremely thin electrode layers. One technique for detecting edge weld uniformity involves ensuring that none of the layers are bent, as this would prevent the entire edge from being welded. The ultrasonic welding machine disclosed herein offers a novel design solution to this problem.

[0021] Referring initially to FIG. 1, an ultrasonic welder 10 includes electrode plies 12 stacked in place to ultrasonically weld edges with a horn assembly 14 held in place by a booster mounting ring 40 (see FIG. 2). Most of the internal components are housed in a case 18, as will be described below. A base 20, as seen in FIG. 1, supports the ultrasonic welder 10 and rests on adjustable legs 22A and 22B. Beneath the horn assembly 14 is an anvil assembly 23. Adjacent to the horn assembly 14 are a leveling spring assembly 21 and a tilt encoder assembly 25 (see FIG. 4). The horn assembly 14 is housed in a carriage block assembly 31 (see also FIG. 5), which will be described in detail below. A key assembly 35 is located above the horn assembly 14. Also visible is a servomotor-driven vertical pressure screw assembly 28 (see also FIG. 3) that applies vertical downward pressure to hold a carriage block 31 (see FIG. 5) described below.

[0022] In Figure 3, the front cover of the case 18 has been removed to reveal the internal components. It can be seen that the servo motor-driven vertical pressure screw assembly 28 includes a ball screw assembly 32 that applies pressure against the carriage block assembly 30. The carriage block assembly 30 houses the rotating stack assembly 34 (see Figure 9), which includes the horn assembly 14, described below, a booster assembly 50 (see Figure 9), and a transducer 38 (see Figure 5). The rotating stack assembly 34 and its components work in concert to impart vibrational energy to the horn assembly 14, causing it to vibrate relative to the anvil assembly 23.

[0023] 8 and 9, the components of the self-leveling rotating stack assembly 34 are shown in exploded view. From this, it can be seen that the horn assembly 14 extends from the weld tip into the booster mounting ring 40 (see also FIG. 6), which in turn extends into the carriage block 30. The booster mounting ring 40, in turn, has a threaded end that threads into the threaded end of the booster mounting sleeve 42 and is securely held in place by a locking nut 44. A large, deep groove ball bearing (single row) 46 fits onto the end of the booster mounting ring 40 and against the locking nut 44. The booster head bridge 42 threads into the self-leveling shell 48. A booster head bridge 50 extends through the self-leveling shell 48 and the booster mounting sleeve 42 until it abuts the horn assembly 14. The horn assembly 14 is firmly held to the booster headplate 50 by threaded bolts 52. At one end, a booster locking ring 54 threads onto the self-leveling shell 48 and is positioned with an O-ring wire 56 and O-ring 58. A locking nut 64, a large, deep groove ball bearing (single row) 62, and an O-ring 60 are fitted to the self-leveling shell 48. The rotating stack assembly 34 has a pair of ball bearing rings on both sides, allowing it to rotate in both directions. The stack assembly's rotational performance can be measured by an encoder assembly (consisting of an encoder bracket 25, encoder sensor 27, and encoder strip 29), and it is returned to a horizontal neutral position by a leveling spring assembly 21.

[0024] 8, the horn assembly 14 fits head-on into the rotating stack assembly 34 using threaded bolts 52 and is positioned by the threaded bolts 52 against the booster headstock 50. In the field or at the factory, this assembly method allows for easy removal and replacement by rotating the horn assembly 14, as it can be easily removed by simply removing the threaded bolts 52. More importantly, this assembly method allows for the horn to be replaced without having to disassemble the ultrasonic welder 10 or other components.

[0025] FIG. 10 shows stacked electrode plies 66 with a bent corner 68. The stack 66 is inserted into the ultrasonic welding machine 10 of the present disclosure with the stack for edge welding. The stack functions to rotate the encoder assembly (comprising the encoder bracket 25, encoder sensor 27, and encoder strip 29) and the leveling spring assembly 21. The bent corner 68 causes the weld edge on the bent side to be thicker than the opposite corner, which is detected by the encoder assembly and prevents further welding. The ability to detect bent plies also reduces the waste of welded electrode ply edges, and removing the bent electrode ply allows the stack to be repaired and achieve the desired edge weld.

[0026] The high-frequency ultrasonic welding unit 10 may be a pneumatically operated ultrasonic welding system, which is common in the industry. Such systems utilize pneumatic cylinders to control force and decelerate the stack. Pneumatic systems have limited inlet and outlet velocities as the contained air moves the system's pneumatically operated actuator. Therefore, pneumatic systems cannot handle sudden changes in direction or speed, limiting the system's distance control. A system that can instantly adjust speed to suit the type of material is ideal for achieving perfectly uniform welds. Improved system control over speed and distance can reduce variability in weld quality.

[0027] Pneumatic systems also utilize static pressure to compress parts engaged in the system. The type of material being worked on can affect the ideal pressure selected, resulting in a weaker weld when static pressure is applied compared to systems that can adapt dynamic pressure to the material's condition. The nature of pneumatic systems further limits control over horn face movement and positioning. The weaknesses of pneumatic ultrasonic welding systems result in less adaptability to external contaminants and types of weld material, as well as greater misalignment between welds than ideal standards.

[0028] A better ultrasonic welding device 10 utilizes an electric motor to bring a sonotrode into contact with the weld material to increase the compressive force of the ultrasonic weld. A sensor, such as a load cell, measures the increase in compressive force. The sensor can directly measure the load on the horn, independent of losses in the system. A software algorithm compensates for deflection of the load cell sensor and loss motion in the electric motor operation. Such a servo motor-based ultrasonic welding device is described in U.S. patent application Ser. No. 15 / 927,114, filed March 21, 2018.

[0029] 12-14, the intermediate holder 31 has concave notches on its sides. These notches, or "depressions," cause the cross-sectional area of ​​the holder 31 to be small at the midpoint and increase toward the welding tip 33. Figure 13A shows the small cross-sectional area of ​​the holder 31 near the midpoint.

[0030] Although the cross-section of the concave notch or depression is small, the concave notch or depression does not allow the ultrasonic waves to propagate uniformly to the welding tip 33 of the horn 14. Therefore, the location, radius, and depth of the concave feature become important. Only through repeated simulation analysis and finite element analysis (FEA) can a geometry be determined that achieves uniform amplitude across the entire welding tip 33 of the horn 14.

[0031] Ultrasonic waves are affected by concave characteristics. For example, as the cross-sectional area increases toward the welding tip 33, the ultrasonic waves bend outward and reach the tip of the welding tip 33 with the same force as if they had traveled in a straight line. This is based on test measurements, as reported in the first-cited U.S. Provisional Patent Application No. 63 / 064,423.

[0032] While the devices, systems, and methods have been described with reference to various embodiments, those skilled in the art will recognize that various changes may be made and that equivalents may be substituted for elements without departing from the scope of the present disclosure. Furthermore, modifications may be made to reflect the findings of the present disclosure and to adapt to particular situations and materials without departing from the essential scope. Therefore, it is not intended that the present disclosure be limited to the particular embodiments disclosed, but rather that the present disclosure may include all embodiments falling within the scope of the appended claims. Furthermore, all citations referenced herein are expressly incorporated herein by reference. [Example]

[0033] recessed horn 15 and 16, horns 114 and 120 were subjected to amplitude analysis using SOLIDWORKS® simulation software manufactured by Dassault Systemes SolidWorks, Inc., 175 Wyman Blvd., Waltham, Massachusetts, ZIP Code 02451, USA. Horns 114 and 210 are both manufactured by Tech-Sonic, Inc., 2710 Sawbury Blvd., Columbus, Ohio, ZIP Code 43235, USA.

[0034] To verify the FEA results, actual horn amplitude data was collected for both horns using a laser. Amplitude was measured at the left edge, left center, center, right center, and right edge of each horn.

[0035] To ensure that both horns were as identical as possible, the knurling patterns and horn dimensions were identical. Both horns were also mounted to the same booster, converter, and shell (Figure 1), with the only difference being that one horn had a concave side and the other did not (Figure 23). For both horns, the amplitude was measured at five locations on the horn surface (as shown in Figures 15 and 16). All measurements were located as close as possible to the knurling to simulate the amplitude the weld surface would experience during the welding process.

[0036] Both horns were measured using both an amplitude gauge and a laser amplitude measurement device to ensure the results were as accurate as possible. The amplitude gauge included in the gauge was mounted fixedly to the machine. This ensured that the gauge would not move easily due to vibration of the horn or any external forces. The laser was also mounted fixedly to the machine. Three laser readings were taken and the average was recorded.

[0037] The results are shown graphically in Figures 17-20. It can be seen that the new horn achieved a more uniform amplitude across the entire width of the welding tip at all test powers. This uniformity can be easily seen by comparing the edge amplitude to the center amplitude in terms of percentage amplitude difference, as shown in the table below.

[0038] [Table 1]

[0039] [Table 2]

[0040] [Table 3]

[0041] [Table 4]

[0042] [Table 5]

[0043] [Table 6]

[0044] [Table 7]

[0045] [Table 8]

[0046] As shown in Figures 17-20, the disclosed concave horn exhibited more uniform amplitude across the weld surface, while the non-concave horn exhibited significantly higher amplitude at the center compared to the ends. The amplitude difference was particularly pronounced at low and high amplitude percentages. The amplitude difference for the non-concave horn compared to the horn with concave sides was very significant (Tables 5-8). For laser readings recorded at 45%, the amplitude difference for the non-concave horn was -38.52% when comparing the left end (measurement point 1) to the center (measurement point 3). Meanwhile, the amplitude difference for the right end (measurement point 5) was -39.45%. For the novel concave horn, the differences were -1.86% and -0.61% when comparing the left end (measurement point 1) to the center (measurement point 3) and the right end (measurement point 5) to the center, respectively. The higher the amplitude, the more significant the difference. For a horn without concave sides, the difference in amplitude between the left end (measurement point 1) and the center (measurement point 3) was -18.08%, and the difference between the right end (measurement point 5) and the center was -18.53%. For a horn with concave sides, the difference in amplitude between the left end and the center was -1.42%, and the difference between the right end and the center was 0%.

[0047] A similar trend was observed in the gauge test. For the horn without concave sides, the amplitude was different at both ends (measurement points 1 and 5) compared to the center point (measurement point 3). Due to the variance inherent in gauge testing, the gauge in this example was used only to determine whether the results recorded in the laser test were representative of the gauge test, but did not necessarily provide an accurate reading.

[0048] The very high amplitude seen in the center of the horn can be problematic during welding. This is because the center may be properly welded, but the ends may not be properly welded. Alternatively, the center may be over-welded, while the ends may be properly welded. Insufficient welding can weaken the area and prevent a sufficient bond for proper electrical conduction. Conversely, excessive welding can weaken the weld, making it brittle. [Example]

[0049] Rotating Stack The welder's own leveling capabilities were evaluated using a test scheme that included 10 good welds, 15 bent welds, and 10 overlapping welds. The welder and rotary horn of Figures 1-11 were used in this example.

[0050] Typical or good weld test results are presented in Table 9 below.

[0051] [Table 9]

[0052] The bent weld test results are presented in Table 10 below.

[0053] [Table 10]

[0054] To determine if the new welder could maintain thickness differential detection when a mixture of unbent and bent foils was used, alternating good / bent welds were prepared. The results are shown in Table 11.

[0055] [Table 11]

[0056] Again, the welder's ability to detect folded foil among unfolded foil was excellent.

[0057] The disclosed welder design is successful in its ability to detect bent foil. All reported tests were performed without rework. The starting height is important to detect good foil from bent foil.

Claims

1. An ultrasonic welding machine (10) having a booster (50) and a self-leveling rotating stack assembly (34) with an ultrasonic horn (14), The ultrasonic horn is (a) a shaft (35) attachable to a source of high frequency ultrasonic vibrations; (b) a transition (37) having a height and a width, the height tapering to have a cross-sectional area smaller than the cross-sectional area of ​​the stem; (c) an intermediate holder (31) having a height and width, the intermediate holder having a cross-sectional area smaller than the cross-sectional area of ​​the switch, the intermediate holder having a constant height and a concave recess on the side; (d) a rectangular welding tip (33) having a cross-sectional area larger than that of the intermediate holder and attachable to the handle; An ultrasonic welding machine comprising:

2. 2. The ultrasonic welding machine according to claim 1, wherein the rectangular welding tip (33) has a cross-sectional area larger than that of the intermediate holder and is attached to the intermediate holder.

3. the ultrasonic horn is annular and attached to the booster; 2. The ultrasonic welding machine of claim 1, wherein the booster has a threaded cavity, and a threaded bolt (52) passing through the annular ultrasonic horn is threadedly engaged with the threaded cavity of the booster.

4. 1. A method for detecting foil fold edges in stacked foils, characterized in that the stacked foils are welded by an ultrasonic welding machine (10) having a pressure booster (50) and a stack assembly (34) with an ultrasonic horn (14), the stack assembly being self-leveling and rotatable.

5. A horn (14) for a high frequency ultrasonic welding horn, comprising: (a) a shaft (35) attachable to a source of high frequency ultrasonic vibrations; (b) a transition (37) having a height and a width, the height tapering to have a cross-sectional area smaller than the cross-sectional area of ​​the stem; (c) an intermediate holder (31) having a height and width, the intermediate holder having a cross-sectional area smaller than the cross-sectional area of ​​the switch, the intermediate holder having a constant height and a concave recess on the side; (d) a rectangular welding tip (33) having a cross-sectional area larger than that of the intermediate holder and attachable to the handle; A horn comprising:

6. An ultrasonic welding machine (10) having a booster (50) and a stack assembly (34) with an ultrasonic horn (14), the improvement comprising: the ultrasonic horn is annular and is attached to the booster, the booster having a threaded cavity, and a threaded bolt (52) passing through the annular ultrasonic horn is threadedly engaged with the threaded cavity of the booster; The ultrasonic horn is (a) a shaft (35) attachable to a source of high frequency ultrasonic vibrations; (b) a transition (37) having a height and a width, the height tapering to have a cross-sectional area smaller than the cross-sectional area of ​​the stem; (c) an intermediate holder (31) having a height and width, the intermediate holder having a cross-sectional area smaller than the cross-sectional area of ​​the switch, the intermediate holder having a constant height and a concave recess on the side; (d) a rectangular welding tip (33) having a cross-sectional area larger than that of the intermediate holder and attachable to the handle; An ultrasonic welding machine comprising:

Images