Ultrasonic wedge bonding machine, bonding head assembly and design method thereof

Abstract

The application aims to provide an ultrasonic wedge bonding machine, a bonding head assembly and a design method thereof. The bonding head assembly comprises a transducer and a cleaver. One end of the transducer is provided with a through hole, and the end face of the one end is provided with a locking hole in communication with the through hole. An inwardly protruding protrusion is arranged on the hole wall of the through hole, and the protrusion is arranged opposite to the locking hole. In the fixed state, the cleaver is arranged in the through hole, the fastener extends into the through hole through the locking hole, and the cleaver is tightly pressed on the plurality of protrusions. In the fixed state, the protrusions abut against the cleaver through contact points, the number of the contact points is multiple, and at least two contact points are arranged to be spaced apart by a first distance along the extension direction of the through hole. Through the bonding head assembly, the transmission efficiency of ultrasonic waves in the ultrasonic wedge bonding machine can be improved, and the welding quality can be improved.

Description

Technical Field

[0001] This invention relates to the field of bonding welding technology, and in particular to an ultrasonic wedge welding machine, a welding head assembly, and a design method thereof. Background Technology

[0002] In an ultrasonic wedge welding machine, the welding head assembly is the working component for bonding, which includes a transducer and a wedge. The transducer, also known as an ultrasonic transducer, converts the electrical signal emitted by the sound source into high-frequency vibrations that are transmitted to the wedge. The wedge has a lead-in channel inside, through which the metal wire for welding is led out. The working part at the free end of the wedge heats, presses, and vibrates the metal wire, causing it to be welded to the substrate to complete the bonding process.

[0003] To ensure welding efficiency, the stability of the wedge in the transducer is crucial. Currently, in ultrasonic wedge welding machines, the wedge is fixed in the transducer by placing it in a through hole at one end of the transducer and securing it with a screw head.

[0004] However, the inventors discovered that the existing method of fixing the cutting blade can easily affect the welding quality and ultrasonic transmission efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a welding head assembly that can improve the transmission efficiency of ultrasound in an ultrasonic wedge welding machine and improve welding quality.

[0006] The welding head assembly for achieving the aforementioned purpose includes a transducer and a wedge. One end of the transducer is provided with a through hole, the inner diameter of which is larger than the outer diameter of the wedge. The through hole is opened radially along the transducer at one end. A locking hole is provided on the end face of the one end, and the locking hole is connected to the through hole.

[0007] The through hole has an inwardly protruding protrusion on its wall. The protrusion is positioned opposite to the locking hole. When fixed, the chopping blade passes through the through hole, and the fastener extends into the through hole through the locking hole and presses the chopping blade against the protrusions.

[0008] In the fixed state, the protrusion abuts against the chopping blade through contact points. There are multiple contact points, including at least two contact points configured to be spaced apart by a first distance along the extension direction of the through hole.

[0009] In one or more embodiments, among the plurality of contact points, at least two contact points are configured to be spaced apart by a second distance circumferentially along the through hole.

[0010] In one or more embodiments, in a fixed state, the point where the fastener and the chopping blade meet is defined as the point of force application, and in the orthographic projection seen along the axial direction of the transducer, a plurality of the contact points are centrally symmetrically distributed with respect to the point of force application.

[0011] In one or more embodiments, the protrusion includes four protrusions. In the clamping state, each of the protrusions contacts and engages with the chopping point. The protrusions include a pair of first protrusions and a pair of second protrusions. The pair of first protrusions are respectively disposed corresponding to the pair of second protrusions along the extension direction of the through hole. The corresponding first protrusions and second protrusions are separated by a first distance in the extension direction of the through hole.

[0012] The pair of first protrusions are spaced circumferentially between each other along the through hole, and the pair of second protrusions are spaced circumferentially between each other along the through hole.

[0013] In one or more embodiments, the first distance satisfies the following relationship:

[0014] d / 2>f·L toc / F;

[0015] Where d is the first distance, f is the frictional force on the cutter head when the working end of the cutter drives the welding wire to move on the surface of the welding material, and L toc The distance from the working end of the chopping blade to the center of the transducer is denoted by , and F is the external force applied to the chopping blade by the fastener.

[0016] In one or more embodiments, the first distance further satisfies the following relationship:

[0017] d is less than 1 / 4 of the amplitude wavelength of the chopping blade vibration.

[0018] In one or more embodiments, the locking hole is a threaded hole, and the fastener is a bolt.

[0019] On the other hand, according to some embodiments of this application, an ultrasonic wedge welding machine is also provided, which includes the welding head assembly as described above.

[0020] Furthermore, according to some embodiments of this application, a method for designing a welding head assembly is also provided, which includes the following steps:

[0021] a. Obtain the outer diameter of the wedge in the welding head assembly;

[0022] b. A through hole is provided at one end of the transducer of the welding head assembly, and the inner diameter of the through hole is larger than the outer diameter of the wedge.

[0023] c. A locking hole is formed on one end face of the transducer, and the locking hole is connected to the through hole;

[0024] d. An inwardly protruding protrusion is provided in the wall of the through hole, the protrusion being disposed opposite to the locking hole, and the protrusion being configured such that, in a fixed state, the protrusion abuts against the chopping blade through contact points, the number of contact points being multiple, including at least two contact points configured to be spaced apart by a first distance along the extension direction of the through hole.

[0025] In one or more embodiments, in step d, the first distance is made to satisfy the following relationship:

[0026] d / 2>f·L toc / F;

[0027] Where d is the first distance, f is the frictional force on the cutter head when the working end of the cutter drives the welding wire to move on the surface of the welding material, and L toc The distance from the working end of the chopping blade to the center of the transducer is denoted by , and F is the external force applied to the chopping blade by the fastener.

[0028] In one or more embodiments, in step d, the first distance is further made to satisfy the following relationship:

[0029] λ / 4>d;

[0030] Where λ is the amplitude wavelength of the chopping blade vibration.

[0031] In one or more embodiments, the amplitude wavelength of the chopping blade vibration is calculated using the following formula:

[0032] nλ=mi(RC / ω) 1 / 2 ;

[0033] Wherein, n is the number of wavelengths of sound waves transmitted on the cutting tool under actual working conditions, R is the radius of the cutting tool, C is the longitudinal wave velocity, ω is the angular velocity, and mi is the reference constant.

[0034] The beneficial effects of this invention are as follows:

[0035] In this welding head assembly, the wedge is held and fixed on both sides by fasteners and protrusions, forming a one-point + multi-point clamping configuration. This provides better constraint on degrees of freedom, increases clamping rigidity, ensures the wedge's installation position and angle, and provides sufficient clamping rigidity to withstand welding forces. This ensures that the wedge's position and perpendicularity remain stable during welding. Simultaneously, the protrusions and wedge contact each other through multiple contact points, correspondingly increasing ultrasonic transmission to multiple channels. This provides high-efficiency ultrasonic transmission and excellent ultrasonic energy transfer pathways, further guaranteeing welding quality.

[0036] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0037] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0038] Figures 1 to 4 A schematic diagram of an existing welding head assembly is shown;

[0039] Figure 5 A half-sectional schematic diagram of some embodiments of the transducer in this welding head assembly is shown;

[0040] Figure 6 A front view schematic diagram of some embodiments of the wedge fixing method in this welding head assembly is shown;

[0041] Figure 7 It shows Figure 6 A magnified view of part A;

[0042] Figure 8 A top view schematic diagram of some embodiments of the wedge fixing method in this welding head assembly is shown;

[0043] Figure 9 A schematic diagram of the contact point distribution in a fixed state according to some embodiments of this welding head assembly is shown;

[0044] Figures 10 to 11 The diagram shows the operation of the chopping blade under working conditions;

[0045] Figure 12 A schematic diagram of ultrasonic transmission when the chopper is tilted is shown when using single-channel excitation;

[0046] Figure 13 A schematic diagram of ultrasonic transmission when the cutting tool is perpendicular is shown using single-channel excitation;

[0047] Figure 14 A schematic diagram of ultrasonic transmission when the chopper is tilted is shown when dual-channel excitation is used;

[0048] Figure 15 A schematic diagram of ultrasonic transmission when the cutting tool is perpendicular is shown when using dual-channel excitation. Detailed Implementation

[0049] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0051] like Figures 1 to 4 A schematic diagram of a conventional welding head assembly is shown. In this assembly, the wedge 91 is placed in a through-hole 93 near the end of the transducer 92 and secured by a screw head 94. The inner diameter of the through-hole 93 is typically larger than the outer diameter of the wedge 91 to facilitate assembly. In this state, since the material is not a perfectly rigid body but will deform under pressure, the actual effect is determined by… Figure 3 As shown, the chopping tool 91 actually contacts the inner wall of the through hole 93 at point 910, so that the chopping tool 91 is fixed at two points in the through hole 93, but the fixing effect is poor. In actual working conditions, the chopping tool 91 will be tilted and shake. At the same time, due to the long length of the chopping tool 91, the tilt of the angle will cause a large offset in the position of the working head 911 of the chopping tool 91. This offset will cause great trouble to the welding quality.

[0052] In order to solve the problems existing in the aforementioned existing methods of fixing the cutting tool, on the one hand, according to some embodiments of this application, a welding head assembly is provided. It is understood that the reference numeral system used in the welding head assembly described in the following one or more embodiments is independent of the reference numeral system used in the various components of the aforementioned existing welding head assembly.

[0053] The welding head assembly includes a transducer 1 and a cutting blade 2. Figure 5 A partial cross-sectional schematic diagram is shown, representing some embodiments of the transducer in this welding head assembly. Figure 6 A front view diagram of some embodiments of the wedge fixing method in this welding head assembly is shown. Figure 7 It shows Figure 6 A magnified view of part A. Figure 8 A top view schematic diagram of some embodiments of the wedge fixing method in this welding head assembly is shown.

[0054] One end of the transducer 1 is provided with a through hole 10. The inner diameter of the through hole 10 is larger than the outer diameter of the chopping blade 2. The through hole 10 is opened through the transducer 1 radially. One end face of the transducer 1 with the through hole 10 is provided with a locking hole 11. The locking hole 11 is connected to the through hole 10.

[0055] An inwardly protruding protrusion 12 is provided on the wall of the through hole 10. That is, the protrusion 12 is provided from the inner wall of the through hole 10 toward the center of the through hole 10. It can be understood that the top of the protrusion 12 toward the center of the through hole 10 protrudes relative to the rest of the through hole 10. It can be a protrusion structure formed on the inner wall of the through hole 10 by means such as welding, or it can be a protrusion structure formed in the pre-formed hole structure by subtractive processing that is higher than other areas of the inner wall of the hole.

[0056] The protrusion 12 is positioned opposite to the locking hole 11. When fixed, the chopping blade 2 passes through the through hole 1. The description of the protrusion 12 and the locking hole 11 being positioned opposite to each other can be understood as follows: with the chopping blade 2 fixed in the through hole 1 as a reference, the protrusion 12 and the locking hole 11 are located on opposite sides of the chopping blade 2. With the through hole 1 itself as a reference, the protrusion 12 and the locking hole 11 are located on opposite sides of the inner wall of the through hole 1.

[0057] The fastener 5 can extend into the through hole 1 through the locking hole 11 and press against the chopping blade 2 located in the through hole 1, and move towards the protrusion side. At this time, since the protrusion 12 is provided to protrude from the inner wall of the through hole 10 toward the center of the through hole 10, the protrusion 12 contacts the chopping blade 2 first. The fastener presses the chopping blade 2 against the multiple protrusions 12 to form a fixed structure in the through hole 1 where the protrusions 12 and the fastener clamp the chopping blade 2 together.

[0058] With the protrusion 12 and fastener 5 clamping and fixing the chopping blade 2, the point of contact between the protrusion 12 and the chopping blade 2 is contact point 120. Figure 9 A schematic diagram of the contact point distribution in a fixed state according to some embodiments of this welding head assembly is shown. The number of contact points 120 is plurality of, including at least two contact points 120 configured to be spaced apart by a first distance d along the extension direction of the through-hole. It is understood that the term "plural" as used herein means two or more (including two), unless otherwise explicitly specified.

[0059] In this welding head assembly, the two sides of the wedge 2 are clamped and fixed by fasteners 5 and protrusions 12, forming a one-point + multi-point clamping configuration. This provides better 6-DOF constraint, improves clamping rigidity, ensures the wedge's installation position and angle, and provides sufficient clamping rigidity to withstand welding forces. This ensures that the wedge's position and perpendicularity remain stable during welding. Simultaneously, the protrusions 12 and the wedge 2 are in contact through multiple contact points 120, correspondingly increasing ultrasonic transmission to multiple channels. This provides high-efficiency ultrasonic transmission and excellent ultrasonic energy transfer pathways, further guaranteeing welding quality.

[0060] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0061] In some embodiments of this welding head assembly, such as Figure 8 As shown, at least two contact points are configured to be spaced apart by a second distance along the circumference of the through hole, thereby forming multi-point contact with the chopping blade 2 along the circumference to achieve more stable clamping of the chopping blade 2.

[0062] In some embodiments of this welding head assembly, the point where the fastener 5 and the chopping blade 2 abut in a fixed state is defined as the point of force application 3, such as... Figure 9 As shown, in the orthographic projection seen along the axis of transducer 1, multiple contact points 120 are centrally symmetrically distributed with respect to the force application point 3. The fixing form with this configuration can achieve uniform clamping force on the chopping blade 2, further ensuring the stability of the clamping effect on the chopping blade 2.

[0063] In some embodiments of this welding head assembly, the protrusion 12 is composed of four protrusions. Each protrusion can be understood as a point-like protrusion structure protruding inward from the hole wall. The protrusions include a pair of first protrusions and a pair of second protrusions. In the clamping state, each protrusion makes point contact with the wedge 2, wherein, as shown... Figure 9As shown, the point contact positions between the first protrusion and the chopping blade 2 are a pair of first contact points 121, and the point contact positions between the second protrusion and the chopping blade 2 are a pair of second contact points 122. The pair of first protrusions are respectively positioned corresponding to the pair of second protrusions along the extension direction of the through hole, that is, in the orthographic projection shown along the extension direction of the through hole, the pair of first protrusions coincides with the pair of second protrusions. The corresponding first and second protrusions are separated by a first distance d along the extension direction of the through hole. The pair of first protrusions are separated by the same distance along the circumference of the through hole, and the pair of second protrusions are separated by the same distance along the circumference of the through hole, thereby ensuring that in the orthographic projection shown along the extension direction of the through hole, the pair of first protrusions coincides with the pair of second protrusions, and in the extension direction of the through hole, the pair of first protrusions are located at the same extension position, and the pair of second protrusions are also located at the same extension position, thus forming the following configuration: Figure 9 The structure shown is designed for four-point clamping, which ensures good stability in clamping the chopping tool 2 and is easy to manufacture.

[0064] In other embodiments with configurations different from those shown in the figure, the protrusion 12 may have other configurations. For example, the protrusion may be composed of two, three, or five protrusions, which respectively engage with the chopping blade 2 in a fixed state. For example, in some embodiments, the protrusion 12 may be a protruding structure arranged along the extension direction of the through hole 10. In this case, the contact portion between the protrusion 12 and the chopping blade can be regarded as a line contact engagement composed of multiple consecutive points.

[0065] Figures 10 to 11 The diagram illustrates the operation of the cleaver under working conditions. Sufficient clamping torque is required to secure the cleaver and balance the torque reflected back from the cleaver head during bonding. Figure 10 As shown, when the clamping force is too small and the clamping stiffness is insufficient, the wedge head 2a will be unable to overcome the frictional force to vibrate, seemingly "sticking" to the welding surface. Ultrasonic energy cannot be effectively transmitted to the bonding surface for effective bonding, resulting in poor bonding and failure to weld, thus failing the bonding thrust test. According to some embodiments of this welding head assembly, the first distance d needs to satisfy the relationship: d / 2 > f·L toc / F. Where d is the first distance, f is the frictional force on the cutter head when the working end of the cutter drives the welding wire to move on the surface of the welding material, and L toc Let F be the distance from the working end of the chopper to the center of the transducer, and F be the external force applied to the chopper by the fastener. Figure 10 As shown, when the first distance d satisfies the relationship: d / 2 > f·L toc At / F, the torque M at the fixed point of the chopping blade 2 holding Torque M greater than that at the weld surface friction， The clamping stiffness is sufficient at this point to effectively output ultrasound.

[0066] Furthermore, in some embodiments of this welding head assembly, the first distance d further satisfies the following relationship: d is less than 1 / 4 of the wavelength of the cleaving blade vibration. If the first distance d is greater than 1 / 4 of the wavelength of the cleaving blade vibration, the phase is very likely to exceed 180 degrees, which will also weaken the ultrasonic output, thereby affecting the welding quality.

[0067] Furthermore, in some embodiments of this welding head assembly, the locking hole 11 is a threaded hole, and the fastener 5 is a bolt, which is tightened into the threaded hole to clamp the cleaver. In other suitable embodiments, the fastener may also be a fixing component of other configurations, such as a rivet.

[0068] On the other hand, according to some embodiments of this application, an ultrasonic wedge welding machine is also provided, which includes a welding head assembly as described in the preceding one or more embodiments.

[0069] In another aspect, according to some embodiments of this application, a design method for a welding head assembly is also provided, characterized by comprising the following steps:

[0070] a. Obtain the outer diameter of the wedge in the welding head assembly;

[0071] b. A through hole is provided at one end of the transducer of the welding head assembly, and the inner diameter of the through hole is larger than the outer diameter of the wedge.

[0072] c. A locking hole is made on one end face of the transducer, and the locking hole is connected to the through hole;

[0073] d. An inwardly protruding protrusion is provided in the wall of the through hole, the protrusion being disposed opposite to the locking hole, and the protrusion being configured such that, in a fixed state, the protrusion abuts against the cutting tool through contact points, the number of contact points being multiple, including at least two contact points configured to be separated by a first distance along the extension direction of the through hole.

[0074] Furthermore, in some embodiments of the design method for this welding head assembly, in step d, the first distance is made to satisfy the following relationship:

[0075] d / 2>f·L toc / F;

[0076] Where d is the first distance, f is the frictional force on the cutter head when the working end of the cutter drives the welding wire to move on the surface of the welding material, and L toc denoted as , where is the distance from the working end of the chopping tool to the center of the transducer, and F is the external force applied to the chopping tool by the fastener.

[0077] Furthermore, in some embodiments of the design method for this welding head assembly, in step d, the first distance is further made to satisfy the following relationship:

[0078] λ / 4>d;

[0079] wherein λ is the amplitude wavelength of the capillary vibration.

[0080] Further, in some embodiments of the design method of the welding head assembly, the amplitude wavelength of the capillary vibration is calculated by the following formula:

[0081] nλ=mi(RC / ω) 1 / 2 ;

[0082] wherein, n is the number of wavelengths that the acoustic wave transmits on the capillary under actual working conditions, R is the capillary radius, C is the longitudinal wave velocity, ω is the angular velocity, and mi is the reference constant.

[0083] The present invention is further illustrated by the following specific embodiment:

[0084] Taking a design of 60KHz as an example, in this case, the capillary 2 can be regarded as a horn with flexural vibration.

[0085] The reference constant mi can be obtained by the following formula:

[0086] cos(mi)cosh(mi)=1.

[0087] The order i is selected to be 5, and mi is calculated to be 14.137.

[0088] the resonance length L at this time re =mi(RC / ω) 1 / 2 in this embodiment, the capillary radius R is 1.585 mm, and L is calculated re to be 66 mm. The acoustic wave transmits 3 wavelengths on the capillary under actual working conditions, so the amplitude wavelength of capillary vibration λ=66 / 3=22 mm.

[0089] during the welding process, the pressure applied by the bonding tip on the capillary is F bonding =6 kgf, and thus the friction force f applied to the capillary tip when the working end of the capillary drives the welding wire to move on the surface of the welded material is calculated to be 1.8 kgf.

[0090] the distance from the working end of the capillary to the center of the transducer is 5 / 6 amplitude wavelengths, thus it is obtained that

[0091] the external force F applied by the fastener on the capillary is 80 kgf, thus 2f·L toc / F=2*1.8 kgf*55 mm / 80 kgf=2.5 mm.

[0092] in conclusion, 2f.L toc / F<d<λ / 4, that is, 2.5 mm<d<5.5 mm, and the preferred value of the first distance d is 4.5 mm.

[0093] In the original 1+1 top-mounted design, the maximum clamping length is 3mm, very close to the required lower limit of 2.5mm, leaving very little margin. Furthermore, the 1 / 8" wedge screw requires a tightening torque of 5kgf.cm, and the internal hexagonal socket is prone to deformation and slippage, limiting its use to less than 5 times. Additionally, this screw requires custom-made parts. In this welding head assembly configuration, the clamping length can be nearly doubled, increasing the margin and thus reducing the required clamping force, lowering the tightening torque, preventing screw failure, and making clamping more reliable.

[0094] Figure 12 A schematic diagram of ultrasonic transmission when the cutting tool is tilted is shown when using single-channel excitation. Figure 13 This diagram illustrates ultrasonic transmission when the cutting tool is perpendicular to the target material using single-channel excitation, for comparison. Figure 12 as well as Figure 13 It can be seen that when the chopping tool 2 is installed incorrectly, the ultrasonic transmission on the chopping tool 2 drops sharply when the node exceeds the excitation zone. However, by making the chopping tool vertically installed, the node is less likely to exceed the excitation zone, thus not affecting the welding quality.

[0095] In some embodiments of this welding head assembly, this welding head assembly can be used to achieve dual (multi) channel input excitation. Figure 14 A schematic diagram of ultrasonic transmission when the cutting tool is tilted is shown when using dual-channel excitation. Figure 15 This diagram illustrates the ultrasonic transmission when the chopper is perpendicular to the blade using dual-channel excitation, for comparison. Figure 12 as well as Figure 13 It is evident that when using dual-channel excitation, even if the chopper 2 is tilted to a certain extent, it will not significantly affect the stability of ultrasonic transmission on the chopper 2. Utilizing this welding head assembly to achieve dual (multi)-channel input excitation improves the efficiency of ultrasonic transmission. The increased effective energy transmission area ensures that the chopper node always falls within the effective excitation area, reducing the sensitivity of the chopper's height-direction installation dimensions and achieving stable and balanced ultrasonic output.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A welding head assembly, characterized in that, The device includes a transducer and a chopping blade. One end of the transducer is provided with a through hole, the inner diameter of which is larger than the outer diameter of the chopping blade. The through hole is opened radially at one end of the transducer. A locking hole is provided on the end face of one end, and the locking hole is connected to the through hole. The through hole has an inwardly protruding protrusion on its wall. The protrusion is positioned opposite to the locking hole. When fixed, the chopping blade passes through the through hole, and the fastener extends into the through hole through the locking hole and presses the chopping blade against the protrusions. In a fixed state, the protrusion abuts against the chopping blade through contact points. The number of contact points is multiple, including at least two contact points configured to be spaced apart by a first distance along the extension direction of the through hole. The first distance satisfies the following relationship: d / 2> f·L toc / F; Where d is the first distance, f is the frictional force on the cutter head when the working end of the cutter drives the welding wire to move on the surface of the welding material, and L toc The distance from the working end of the chopping blade to the center of the transducer is denoted by , and F is the external force applied to the chopping blade by the fastener.

2. The welding head assembly as described in claim 1, characterized in that, Of the plurality of contact points, at least two contact points are configured to be spaced apart by a second distance along the circumference of the through hole.

3. The welding head assembly as described in claim 1, characterized in that, In a fixed state, the point where the fastener and the chopping blade meet is defined as the point of force application. In the orthographic projection seen along the axial direction of the transducer, a plurality of contact points are distributed in a centrally symmetrical manner with respect to the point of force application.

4. The welding head assembly as described in claim 3, characterized in that, The protrusion includes four protrusions. In the clamping state, each of the protrusions contacts and engages with the chopping blade. The protrusions include a pair of first protrusions and a pair of second protrusions. The pair of first protrusions are respectively arranged to correspond to the pair of second protrusions along the extension direction of the through hole. The corresponding first protrusions and second protrusions are separated by a first distance along the extension direction of the through hole. The pair of first protrusions are spaced circumferentially between each other along the through hole, and the pair of second protrusions are spaced circumferentially between each other along the through hole.

5. The welding head assembly as described in claim 1, characterized in that, The first distance further satisfies the following relationship: d is less than 1 / 4 of the amplitude wavelength of the chopping blade vibration.

6. The welding head assembly as claimed in claim 1, characterized in that, The locking hole is a threaded hole, and the fastener is a bolt.

7. An ultrasonic wedge welding machine, characterized in that, Includes the welding head assembly as described in any one of claims 1 to 6.

8. A design method for a welding head assembly, characterized in that, Includes the following steps: a. Obtain the outer diameter of the wedge in the welding head assembly; b. A through hole is provided at one end of the transducer of the welding head assembly, and the inner diameter of the through hole is larger than the outer diameter of the wedge. c. A locking hole is formed on one end face of the transducer, and the locking hole is connected to the through hole; d. An inwardly protruding protrusion is provided in the wall of the through hole, the protrusion being disposed opposite to the locking hole, and the protrusion being configured such that, in a fixed state, the protrusion abuts against the chopping tool through contact points, the number of contact points being multiple, including at least two contact points configured to be spaced apart by a first distance along the extension direction of the through hole; the first distance is made to satisfy the following relationship: d / 2> f·L toc / F; Where d is the first distance, f is the frictional force on the cutter head when the working end of the cutter drives the welding wire to move on the surface of the welding material, and L toc The distance from the working end of the chopping blade to the center of the transducer is denoted by , and F is the external force applied to the chopping blade by the fastener.

9. The design method of the welding head assembly as described in claim 8, characterized in that, In step d, the first distance is further made to satisfy the following relationship: λ / 4>d; Where λ is the amplitude wavelength of the chopping blade vibration.

10. The design method of the welding head assembly as described in claim 9, characterized in that, The amplitude and wavelength of the chopping blade vibration are calculated using the following formula: nλ= ; Where n is the number of wavelengths of the sound wave propagating on the cutting tool under actual working conditions, R is the radius of the cutting tool, and C is the longitudinal wave velocity. Angular velocity, This is a reference constant.

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