Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
  • B23K20/10—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating making use of vibrations, e.g. ultrasonic welding
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/531—Electrode connections inside a battery casing
  • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/502—Interconnectors for connecting terminals of adjacent batteries; Interconnectors for connecting cells outside a battery casing
  • H01M50/514—Methods for interconnecting adjacent batteries or cells
  • H01M50/516—Methods for interconnecting adjacent batteries or cells by welding, soldering or brazing

Definitions

• the present disclosure relates to high-frequency ultrasonic welding and more particularly to a new horn design therefor.
• the use of high-frequency ultrasonic vibrations to create a weld between materials has been known since the 1960s.
• Ultrasonic welders create a weld using friction generated by the ultrasonic vibrations applied to the materials, rather than application of heat to the materials.
• Ultrasonic welding has proven to be effective in joining both plastics and metals, and has been applied in a number of industries, from toy production to the automotive and aerospace industries. Ultrasonic welds are popular due to the ease with which a weld can be created and the low cost per weld. Ultrasonic welds are ideal for joining small parts.
• Ultrasonic welding is an alternative method to arc or heat welding, or soldering, eliminating consumables, such as solder or flux, component burn back, cooling water requirements and high-energy use.
• An additional advantage of ultrasonic welding operations is the minimal heat that is generated during the welding process, minimizing component damage.
• Ultrasonic metal welding is adapted for the assembly of similar and dissimilar non-ferrous metals used in electronic components and pipe sealing. Parts to be joined by ultrasonic welds are held together under pressure between the ultrasonic horn and anvil. Ultrasonic vibrations of a frequency of about 20 to 40 kHz are applied, and vibration of the horn causes the parts to scrub together, with resultant shear forces removing surface contaminants and exposing bare metal areas.
• Ultrasonic welds are achieved in plastics and metals through different processes. When applied to plastics, the friction created by the ultrasonic vibrations is sufficient to melt the joined portions of the materials, creating a weld when cooled.
• the weld time for an ultrasonic weld is typically very short, with weld times generally ranging between 200 and 400 milliseconds.
• the basic components of ultrasonic welding systems are a press, an anvil, an ultrasonic stack assembly, an ultrasonic generator or power supply, and an electronic controller.
• the workpieces to be welded are placed between the press and the anvil, with the press applying pressure to the pieces.
• the anvil allows the ultrasonic vibrations to be directed to the surfaces of the materials.
• the nest or anvil, where the workpieces (parts) are placed, allows the high frequency vibration generated by the stack assembly to be directed to the interfaces of the weld substrates.
• the ultrasonic stack assembly is commonly composed of a converter, a booster, and a sonotrode or “horn.”
• the converter converts the electrical energy into a mechanical vibration; the booster modifies the amplitude of the vibration; and the sonotrode applies mechanical vibration to the parts to be welded.
• These three elements are typically tuned to resonate at the same ultrasonic frequency (typically 20, 35 or 40 kHz).
• These stack assembly components are connected to an electronic ultrasonic generator that delivers high power AC signal to the stack assembly, while matching the resonance frequency of the stack assembly.
• the user issues commands for the system via the controller, which controls the movement of the press, actuates the stack assembly power supply, conveying weld inducing electrical signal to the ultrasonic stack assembly.
• the converter portion of the stack assembly converts the electrical signal into a mechanical vibration, while a booster can be utilized to modify the vibration amplitude.
• the horn applies the vibrations to the workpiece.
• Welding horns generally are formed from a shank attached to a welding tip.
• the quality and success of an ultrasonic weld is dependent on a number of factors, including signal amplitude, weld time, weld pressure, weld speed, hold time, and hold pressure.
• the appropriate amount of each of these factors is affected by the types of subject materials for the weld and can also vary within a single material.
• 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, the design of the horn and booster, and modulation of electrical inputs to the converter.
• Laminate lithium ion batteries find wide use in electric vehicles, both cars and trucks.
• laminate batteries are increasing in width and in size by adding more and more laminates.
• This increase in battery size has created challenges for ultrasonic welding systems.
• conventional horns have difficulty in maintaining a uniform weld across the width of the laminate batteries. Due to the ply thinness, corners of the plies can become folded or “dog-eared” usually at the corner during handling and before welding. The dog-eared ply, then, will not be welded across its width and will not be active in the later formed battery. It is to the detection of such folds that the present invention is addressed.
• An ultrasonic welder (10) has a booster (50) and stack assembly (34) carrying an ultrasonic horn (14).
• the stack assembly is self-leveling and rotational.
• the ultrasonic horn is annular and is mounted against the booster, which has a threaded cavity, by a threaded bolt (52) that passes through the annular ultrasonic horn and into the threaded cavity of the booster.
• the horn (14) for high-frequency ultrasonic welding includes a shank formed from a shaft portion (35) attachable to a source of high-frequency ultrasonic vibration, a transition (37) having a height and a width.
• the transition cross-sectional area is smaller than the shaft cross-sectional area by tapering its height.
• the transition is attached to an intermediate holder (31) having a height and a width, and a cross-sectional area that is smaller than the transition cross- sectional area.
• the intermediate holder has a uniform height and side concave width dimples.
• the intermediate holder carries a rectangular welding tip (33) having a cross-sectional area larger than the intermediate holder cross-sectional area. The opposite disposed concave areas result in a more uniform weld across the entire horn welding edge.
• a method for detecting a folded edge of a foil in a stack of foils included welding the stack of foils with an ultrasonic welder (10) having a booster (50) and stack assembly (34) carrying an ultrasonic horn (14), wherein the stack assembly is self- leveling and rotational.
• horn assembly 14 fits into rotational stack assembly 34 from the front and is held in position by threaded bolt 52 against booster front mount 50.
• such method of assembly means that horn assembly 14 can be easily removed by the simple removal of threaded bolt 52; thus, making rotation of horn assembly or its removal and replacement easy. More importantly, such method of construction enables changing of the horn without the need for any further disassembly of ultrasonic welding machine 10 or any of its other components.
• FIG. 1 is an isometric view of a high-frequency ultrasonic self-leveling welding system disclosed herein;
• FIG. 2 is a side view of the welding head showing the horn welding an edge of a stack of battery plies;
• FIG. 3 is a front view of the high-frequency ultrasonic self-leveling welding system with its front cover removed;
• FIG. 4 is a close up front view of the welding horn
• Fig 4A is a perspective view of the encoder.
• the encoder bracket 25 has a encoder sensor 27 attached to its back side that reads the position of the encoder strip 29 in a slot of booster mounting ring 40;
• FIG. 5 is an isometric view of the welding assembly
• FIG. 6 is an isometric view of the self-aligning stack
• FIG. 7 is a front view of the horn
• FIG. 8 is a sectional view taken along line 8-8 of FIG. 7;
• Fig 8A is an enlarged view of the vibration absorbing O rings and mounting of the booster 50;
• FIG. 9 is an isometric expanded view of the stack assembly components
• FIG. 10 is an isometric view of a stack of battery plies show one of the plies being dogeared (folded).
• FIG. 11 is a close up front view of the welding assembly in its welding position.
• FIG. 12 is a side elevational view of the disclosed novel horn of FIG. 3;
• FIG. 13 is a front view of the disclosed novel horn of FIG. 3;
• FIG. 13A is a sectional view taken along line 13A-13A of FIG. 12;
• FIG. 14 is a top/bottom view of the disclosed novel horn of FIG. 12;
• FIG. 15 is an isometric view of the disclosed novel horn with side cut-outs or niches or concaves;
• FIG. 16 is an isometric view of a prior art horn without the side cut-outs or niche.
• FIG. 17 graphically displays the experimental amplitude results (gauge measurement) of the Example for one embodiment of the novel horn actuated at various power levels of the welding unit over various points across the welding horn;
• FIG. 18 graphically displays the experimental amplitude results (gauge measurement) of the Example for the prior art horn actuated at various power levels of the welding unit over various points across the welding horn;
• FIG. 19 graphically displays the experimental amplitude results (laser measurement) of the Example for one embodiment of the novel horn actuated at various power levels of the welding unit over various points across the welding horn;
• FIG. 20 graphically displays the experimental amplitude results (laser measurement) of the Example for the prior art horn actuated at various power levels of the welding unit over various points across the welding horn;
• FIG. 21 is an isometric view of one embodiment of the novel horn showing several numerically labelled points across the horn and several alphabetically labelled points along the longitudinal length or the horn;
• FIG. 22 graphically displays the experimental results of the Example for the novel horn of FIG. 12 actuated at 100% of the power of the welding unit;
• FIG. 23 is an isometric view of the prior art horn showing several numerically labelled points across the horn and several alphabetically labelled points along the longitudinal length or the horn;
• FIG. 24 graphically displays the experimental results of the Example for the prior art horn of FIG. 14 actuated at 100% of the power of the welding unit
• an ultrasonic welding machine 10 has a stack of electrode plies, 12, in position for an edge to be ultrasonically welded by a horn assembly, 14, held in position by a booster mounting ring, 40 (see FIG. 2). Most of the stock components are housed within a case, 18, and which will be disclosed below.
• a base, 20, supports ultrasonic welding machine 10 and sits on adjustable feet, 22A and 22B, visible in FIG. 1.
• Located beneath horn assembly 14 is an anvil assembly, 23.
• Adjacent to horn assembly 14 is a leveling spring assembly, 21 , and a tilt encoder assembly, 25, (see FIG. 4).
• Horn assembly 14 is housed within a carriage block assembly, 31 (see also FIG.
• horn assembly 14 Above horn assembly 14 is a key assembly, 35. Also seen is a servo motorized vertical pressure screw assembly, 28, (see also FIG. 3) for exerting vertical downward pressure for holding a carriage block, 31 , (see FIG. 5) to be described later herein.
• Servo motorized vertical pressure screw assembly 28 is seen to include a ball-screw assembly, 32, that exerts pressure against carriage block assembly 30 within which houses a rotational stack assembly, 34, (see FIG. 9) that includes horn assembly 14, a booster assembly, 50, (see FIG. 9) and a converter, 38, (see FIG. 5), each of which will be described further below.
• Rotational stack assembly 34, and its components, operate in convention fashion for imparting vibrational energy to horn assembly 14, which vibrates against anvil assembly 23.
• horn assembly 14 extends from its welding tip into a booster mounting ring, 40, (see also FIG. 6), which in turn extends inside carriage block 30.
• Booster mounting ring 40 in turn has a threaded end that screws into internally threaded end of a booster mounting sleeve, 42, with a locking nut, 44, holding them firmly threaded together.
• a large deep groove ball bearing (single row), 46 fits over an end of booster mounting ring 40 and against locking nut 44.
• Booster front mount 42 is screwed into a self-leveling shell, 48.
• a booster front mount, 50 extends through self-leveling shell 48, booster mounting sleeve 42 and against horn assembly 14.
• Horn assembly 14 is held tight against booster front mount 50 by a threaded bold, 52.
• a booster locking ring, 54 screws into self-leveling shell 48 with an O-ring gland, 56, and an O-ring, 58, in position.
• Trapped against self-leveling shell 48 are a locking nut, 64, large deep groove ball bearing (single row), 62, and an O-ring, 60.
• Rotational stack assembly 34 then, has a pair of ball bearing rings at either end for it to rotate in both directions.
• the stack assembly’s ability to rotate can be measured by an encoder assembly (consisting of encoder bracket 25, encoder sensor 27, and encoder strip 29) and is returns to its neutral horizontal position by leveling spring assembly 21.
• horn assembly 14 fits into rotational stack assembly 34 from the front and is held in position by threaded bolt 52 against booster front mount 50.
• such method of assembly means that horn assembly 14 can be easily removed by the simple removal of threaded bolt 52; thus, making rotation of horn assembly or its removal and replacement easy. More importantly, such method of construction enables changing of the horn without the need for any further disassembly of ultrasonic welding machine 10 or any of its other components.
• FIG. 10 shows a stack of electrode plies, 66, with a bent corner, 68.
• stack 66 is inserted for end welding into disclosed ultrasonic welding machine 10 with the stack’s ability to rotate, the encoder assembly (consisting of encoder bracket 25, encoder sensor 27, and encoder strip 29), and leveling spring assembly 21 , bent corner 68 makes that side of the weld edge thicker than the opposite corner that can be sensed by the encoder assembly and no welding procedure initiated.
• This ability to sense folded plies results in less rejection of edge welded electrode plies and the recovery of such stack by removal of the bend electrode ply for proper edge welding.
• High-frequency ultrasonic welding unit 10 can be a pneumatically actuated ultrasonic welding system, as are common in the industry. These systems utilize pneumatic cylinders to control the force and down speed of the stack. In a pneumatic system, the entry and exhaust rate at which the air contained moves through the pneumatic actuators of the system is limited. Consequently, the pneumatic systems are unable to achieve abrupt changes in direction and velocity, as well as limiting the system’s distance control. A system that is able to adjust its velocity instantaneously to adapt to variations in the materials would ideally produce perfectly consistent welds. Reduced deviations in weld quality will occur when the system’s control over velocity and distance is improved.
• Pneumatic systems also use static pressure to compress parts engaged by the system. As variations in the subject materials may affect the ideal pressure to be employed, a static pressure is more likely to result in a weaker weld than a system that can apply dynamic pressure to adapt to the conditions presented by the materials.
• the character of pneumatic systems further provides limited control over the movement and positioning of the horn face. The weaknesses in pneumatic ultrasonic welding systems lead to greater than ideal standard deviations between welds, as well as reduced adaptability to outside contaminants and weld material variations.
• a better ultrasonic apparatus 10 uses an electric motor to bring the Sonotrode into contact with the weld material in order to develop a compressive force for ultrasonic welding.
• a sensor such as a load cell, measures the compressive force developed. The sensor directly can measure the load on the Horn independent of system losses.
• a software algorithm can compensate for deflection of the load cell sensor and lost motion in the electric motor actuating movement.
• intermediate holder 31 has concave cutouts at its sides. Such cutouts or “dimples” result in holder 31 having a smaller cross-sectional area about its midpoint with a larger cross-sectional area towards welding tip 33.
• FIG. 13A shows the smaller cross-sectional area about the midpoint of holder 31 .
• the ultrasonic waves are influenced by the concave features in such a way that, as the cross-sectional area begins to increase towards welding tip 33, the waves bend outwardly and reach the extreme ends of welding tip 33 with a similar strength as those that continue straight ahead. This is based on test measurements, as reported in provisional 63/064,423, cited above.
• horns 114 and 120 were subjected to amplitude analysis using SOLIDWORKS® Simulation by Dassault Systemes SolidWorks Corporation, 175 Wyman Street, Waltham, MA 02451. Both horns 114 and 210 were manufactured by Tech-Sonic, Inc., 2710 Sawbury Blvd., Columbus, OH 43235 USA.
• the knurling pattern, as well as the dimensions of the horns, are the same. Both horns are also attached to the same booster, converter, and shell (FIG. 1), the only difference is the concave faces on the side of the horn compared to the horn without the concave side (FIG. 23). Both horns will have their amplitudes measured at 5 points on the horn’s face (as shown on FIGS. 15 and 16), all points are positioned, as close as they can possibly be, to the knurling to simulate the amplitude that a weld surface experiences during a welding process.
• the horns are both measured using an amplitude gauge, as well as a laser amplitude measurer, to ensure the results are as accurate as possible.
• the setup for the amplitude gauge included a gauge is fixed on the machine to make sure that the gauge could not be moved around easily by the horn’s vibration or any other external forces.
• the laser setup also was fixed onto a machine. The laser readings are done 3 times and the average is recorded.
• Table 2 Amplitude difference in percentage of the different points on the horn compared to the middle point.
• the disclosed side concave horn shows a more uniform amplitude across its weld surface, while the horn without the concave sides has a significantly higher amplitude in the center compared to the sides as shown on FIGS. 17-20.
• the differences in amplitude are especially obvious on the lower amplitude % as well as the higher end.
• the difference in amplitude for the horn without concaved sides compared to the concave sides is quite significant (Table 2).
• the horn without the concave sides has an amplitude difference of -38.52% from the left end (point 1) compared to the middle (point 3), while the right end (point 5) has a amplitude difference of -39.45%.
• the concave side horn has a left end to middle amplitude difference of - 1.42% and a right end to middle amplitude difference of 0%.
• the gauge test also resulted in similar trends. Where the far ends (points 1 and 5) show significantly different amplitudes compared to the middle point (point 3) on the horn without the concave sides.
• the gauge test has a lot of variance to it so its use in this case is to see whether the trends recorded using the laser test are mirrored on the gauge test, and not necessarily to obtain an accurate reading.
• test outline included 10 good welds, 15 folded welds, and 10 alternating welds to evaluate the welder’s self levelling capability.
• the welder and rotational horn of FIGS. 1 -11 was used in this example.
• the disclosed welder design was a success with its capability in detecting fold foils. All of the reported tests were conducted without any retries. The starting height is critical in detecting good foils from those that were folded.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)

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• 2021
  • 2021-08-11 JP JP2022515525A patent/JP2023538468A/ja active Pending
  • 2021-08-11 EP EP21856617.2A patent/EP4196310A1/de active Pending
  • 2021-08-11 KR KR1020237007181A patent/KR20230049665A/ko unknown
  • 2021-08-11 WO PCT/US2021/045475 patent/WO2022035924A1/en active Application Filing

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