Converter for ultrasonic welding device having increased arc resistance

Abstract

To provide a converter for an ultrasonic welding device having increased arc resistance.SOLUTION: A converter 206 for an ultrasonic welder includes a stack of piezoelectric disks 24 stacked alternately with metal conductor disks 16 therebetween; and a back driver 10 and a front driver 12 disposed on opposite ends of the stack of piezoelectric disks 24. The piezoelectric disks 24 include an outer perimeter surface 26 that extends radially outward beyond the metal conductor disks 16. The outer perimeter surface 26 includes an undulating surface that increases the arc length.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates to ultrasonic devices, and more particularly to transducers for ultrasonic welding devices having increased arc resistance. [Background technology]

[0002] This section provides background information related to the present disclosure that is not necessarily prior art.

[0003] Ultrasonic transducers, common in the ultrasonic welding art, use piezoelectric material to convert electrical power into ultrasonic mechanical motion. A typical design of a relatively high power transducer, also common in the art, is shown in Figure 4. The transducer includes a stack of disc-shaped piezoelectric rings 14, electrode plates 16 between the rings 14, a back driver mass 10, and a front driver mass 12, all held together under tension by a bolt 18 toward the center.

[0004] One of the factors that can lead to the design of more powerful transducers for ultrasonic welding is the increase in the voltage applied to the piezoelectric disks in the transducer. There is a physical limit as to the practical maximum voltage that can be applied, and beyond this limit arcing begins to occur between the plates that supply the voltage, typically located between the piezoelectric disks. These arcs usually travel on the surfaces at the edges of the piezoelectric disks. In the present technology, the path length of the surfaces at the inner and outer edges of these disks is a straight line with the least possible resistance to the arc.

[0005] One prior art method that helps mitigate arcing is the use of an insulating coating on the outside of the piezoelectric stack. Typically, high power piezoelectric stacks have a hole in their center to accommodate the bolt that holds the stack together under compression. In the prior art, this hole is not coated because it is difficult to apply a coating after the stack is assembled. If the coating is applied and dries before assembly, the coating will crack when the bolt is applied. If the coating is applied wet before assembly, the coating will get on the bolt when the bolt is inserted (which is typically done manually) and prevent assembly. Summary of the Invention [Problem to be solved by the invention]

[0006] This section provides a general overview of the disclosure and is not an exhaustive disclosure of its entire scope or all of its features. [Means for solving the problem]

[0007] One aspect of the present disclosure is to increase the arc path length of the end faces on the piezoelectric material, thereby increasing the resistance to arcing between the plates, thereby enabling more powerful transducer designs.

[0008] Another aspect of the present disclosure is to apply a wet insulating coating inside all the holes inside the piezoelectric stack before the stack is assembled. Jigging is used to hold the stack precisely in place. The compression bolt(s) that go inside this or these hole(s) are mechanically precisely positioned to avoid contact with the wet coating and then tightened while the coating is wet. The entire assembly is then allowed to dry. This also increases the resistance to arcing and therefore also allows for a more powerful transducer design.

[0009] The ultrasonic welding transducer includes a stack of alternating piezoelectric disks with metal conductor disks therebetween. A pair of driver plates are disposed on either side of the stack of piezoelectric disks. The piezoelectric disks include an outer periphery having an increased arc length. The outer periphery of the piezoelectric disks can include a wavy surface.

[0010] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0011] The drawings described herein are only for purposes of illustrating selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a workpiece machining apparatus in accordance with an exemplary embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a transducer in accordance with the principles of the present disclosure. [Figure 3A] FIG. 3A is a schematic diagram illustrating the assembly process of a transducer according to the principles of the present disclosure. [Figure 3B] FIG. 3B is a schematic diagram illustrating the assembly process of a transducer according to the principles of the present disclosure. [Figure 3C] FIG. 3C is a schematic diagram illustrating the assembly process of a transducer according to the principles of the present disclosure. [Figure 3D] FIG. 3D is a schematic diagram illustrating the assembly process of a transducer according to the principles of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view of a conventional transducer. [Figure 5A] FIG. 5A is an exemplary cross-sectional view of an alternative cross-section of an edge surface of a piezoelectric disk. [Figure 5B] FIG. 5B is an exemplary cross-sectional view of an alternative cross-section of an edge surface of a piezoelectric disc. [Figure 5C]FIG. 5C is an exemplary cross-sectional view of an alternative cross-section of an edge surface of a piezoelectric disc. [Figure 5D] FIG. 5D is an exemplary cross-sectional view of an alternative cross-section of an edge surface of a piezoelectric disc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0014] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0015] The exemplary embodiments are provided so that the disclosure will be thorough and will fully convey the scope of the present disclosure to those skilled in the art. Numerous specific details are described, such as examples of specific components, devices, and methods, to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that the exemplary embodiments can be embodied in many different forms, and that none of these should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0016] The terms used herein are for the purpose of describing only certain exemplary embodiments and are not intended to be limiting. As used herein, the singular forms "a," "an," and "the" may be intended to include the plural unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and thus specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein should not be construed as necessarily requiring their execution in the particular order described or illustrated, unless specifically identified as an order of execution. It should also be understood that additional or alternative steps may be employed.

[0017] When an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, directly engaged to, directly connected to, or directly coupled to the other element or layer, or there may be intervening elements or layers present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may not be intervening elements or layers present. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0018] Terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as "first", "second", and other numerical terms, when used herein, do not imply an arrangement or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section described below can be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0019] Spatially relative terms such as "inside," "outside," "below," "lower," "top," and the like may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as shown in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, an element described as "below" or "below" another element or feature would be oriented "on top" of the other element or feature. Thus, the exemplary term "below" may encompass both an orientation of above and below. The device may be oriented in other directions (rotated 90 degrees or in other directions) and the spatially relative descriptors used herein would be interpreted accordingly.

[0020] Referring to FIG. 1, a model of a typical prior art ultrasonic system 100 is shown having an ultrasonic stack 102 and an ultrasonic power source 104. It should be understood that the ultrasonic system 100 can be any type of ultrasonic system having an ultrasonic stack excited by an ultrasonic power source. Typical components of the ultrasonic stack 102 include an ultrasonic transducer 106, a booster 108, and an ultrasonic horn 110. It should be understood that not all ultrasonic stacks 102 include a booster 108. It should be further understood that not all ultrasonic stacks 102 include an ultrasonic horn 110. The ultrasonic horn 110 often has one or more ultrasonic horn tips (not shown). The booster 108 and the ultrasonic horn 110 are ultrasonically connected (either directly or via another component) to the ultrasonic transducer 106. In the example of Figure 1, a booster 108 is attached to the ultrasonic transducer 106, which ultrasonically connects the booster 108 and the ultrasonic transducer 106, and an ultrasonic horn 110 is attached to the booster 108, which ultrasonically connects the ultrasonic horn 110 and the booster 108, thereby ultrasonically connecting the ultrasonic horn 110 and the ultrasonic transducer 106 via the booster 108.

[0021] The power supply 104 is controlled by a controller 114 that includes a memory 116. It should be understood that the controller 114 can be included in the power supply 104 or can be separate from the power supply 104.

[0022] The ultrasonic system 100 often includes an anvil 122 that is supported and contacted by the ultrasonic horn tip 112 as the workpiece being processed is being processed. For example, if two metal or plastic parts 124 are being welded together, they are supported on the anvil 122 and pressed together by the ultrasonic horn tip during the welding process as the actuator 120 moves the ultrasonic laminate 102 relative to the two parts 124, where the horn tip also ultrasonically vibrates against one of the parts to ultrasonically weld the two parts 124 together. The actuator 120 is controlled by a controller 126, which may be a separate controller from the controller 114 of the ultrasonic power source 104, or the controller 114 of the ultrasonic power source 104 may control the actuator 120.

[0023] A prior art transducer 106 will be described with reference to the cross-sectional view of FIG. 4. The transducer 106 includes a back driver 10 and a front driver 12, each of which may be made of metal. A plurality of piezoelectric disks 14 are stacked in alternating fashion with a metal conductor disk 16 sandwiched between them. Although a stack of piezoelectric disks 14 and metal conductor disks is shown, it should be understood that a single piezoelectric disk 14 may be utilized between the back driver 10 and the front driver 12. The piezoelectric disk or disks 14 may be made of a piezoelectric ceramic material. The transducer 106 may be held together by bolts 18, which are inserted through holes 10a in the back driver 10, holes 14a in each of the piezoelectric disks 14, holes 16a in each of the metal conductor disks 16, and threaded into threaded holes 12a in the front driver 12.

[0024] One factor that can lead to the design of a more powerful transducer 106 is the increase in the voltage applied to the piezoelectric disks 14 within the transducer. There is a physical limit as to the practical maximum voltage that can be supplied, beyond which arcing begins to occur between the metallic conductor disks 16 that supply the voltage, located between the piezoelectric disks 14. These arcs typically travel on the surfaces of the outer diameter of the piezoelectric disks and the inner diameter of the bore in the piezoelectric disks 14. In the present technique, the surface path length on the inner and outer surfaces of these disks 14 is a straight line with the least possible resistance to the arc, as shown in FIG. 4.

[0025] Referring to FIG. 2, a cross-sectional view of an exemplary transducer 206 according to the principles of the present disclosure is shown. Similar to the conventional transducer 106, the transducer 206 according to the example of the present disclosure includes a back driver 10 and a front driver 12, each of which may be made of metal. A plurality of piezoelectric disks 24 are stacked in alternating fashion with a metal conductor disk 16 sandwiched between them. The piezoelectric disks 24 may be made of a piezoelectric ceramic material or other piezoelectric material. The transducer 206 may be held together by a bolt 18 inserted through a hole 10a in the back driver 10, a hole 24a in each of the piezoelectric disks 24, a hole 16a in each of the metal conductor disks 16, and threadedly engaged with a threaded hole 12a in the front driver 12.

[0026] The piezoelectric disk 24 includes an outer peripheral surface 26 that can be provided with a wavy or other surface that increases the arc length along the outer peripheral surface 26. The "arc length" is the linear distance along the outer peripheral surface from one edge of the outer peripheral surface to the other edge. In the prior art of FIG. 4, the outer peripheral surface of the piezoelectric disk 14 is a cylindrical surface, so the arc length is equal to the thickness of the piezoelectric disk 14. In contrast, the piezoelectric disk 24 of the example of the present invention has a wavy outer peripheral surface 26 to increase the linear distance along the outer peripheral surface and therefore increase the arc length compared to the thickness of the piezoelectric disk 24. One aspect of the present disclosure is to increase the path length of these edges on the piezoelectric material, thereby increasing the resistance to arcing between the plates, thereby enabling a more powerful transducer design.

[0027] The embodiment of the wavy surface shown in FIG. 2 is one way to increase the path length on the edge. Any geometric shape that can increase the path length (and therefore the arc length) of the piezoelectric edge over the path length of a straight line can be used as an alternative embodiment. Thus, as shown in FIG. 5A, the wavy surface can be inverted so that it undulates inward instead of outward. Yet another exemplary embodiment, as shown in FIG. 5B, is for the surface to be just rounded. This has the advantage of being easy to manufacture. Alternatively, the outer periphery can be scalloped, as shown in FIG. 5C. Yet another embodiment, as shown in FIG. 5D, is to have a pointed surface, which has the advantage of being easy to manufacture. Alternatively, the surface can be inwardly pointed. All the above embodiments can be repeated over the surface or combined in any combination over the surface. The preferred shape of the piezoelectric material is a substantially disk-like ring. Alternatively, the outer shape of the piezoelectric disk 24 does not have to be circular, but can be any shape.

[0028] One prior art method that helps mitigate arcing is the use of an insulating coating on the outside of the piezoelectric stack. Typically, high power piezoelectric stacks have a hole in their center to accommodate the bolt that holds the stack together under compression. In the prior art, this hole is not coated because it is difficult to apply a coating after the stack is assembled. If the coating is applied and allowed to dry before assembly, when the bolts are applied, the coating will crack when the disks are compressed. If the coating is applied wet before assembly, the coating will get on the bolts when they are installed (which is typically done manually) and prevent assembly.

[0029] Another aspect of the present invention is to apply a wet insulating coating to the inside of any holes in the piezoelectric stack before the stack is assembled. With reference to Figures 3(a)-3(d), the transducer assembly process is shown. As shown in Figure 3(a), a fixture or jig 50 is shown, which includes a cavity 52. ​​As shown in Figure 3(b), the components 10, 12, 24, 16 of the transducer assembly are inserted into the cavity 52 of the jig 50 in a stacked relationship. As further shown in Figure 3(b), a spray nozzle 54 can then be inserted into the holes 10a, 24a, and 16a of the components 10, 24, and 16, and a spray of insulating coating can be applied by a spray device 56 to the inside of the holes 10a, 24a, 16a. As shown in FIG. 3(c), the bolt 18 can be precisely mechanically placed in the hole by an automated system 58 to avoid contact with the wet coating, and can be threaded into the threaded hole 12a in the front driver 12 while the coating is wet. The transducer assembly 24 can then be removed from the jig 50, and the exterior can also be coated with an insulating coating. The entire assembly 24 is then allowed to dry. The insulating coating increases the resistance to arcing both externally and internally, thus also allowing for a more powerful transducer design.

[0030] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, are interchangeable where applicable, and may be used in selected embodiments even if not specifically shown or described. It may also be modified in many ways. Such modifications should not be considered as departures from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

Claims

1. A transducer for an ultrasonic welding machine, At least one piezoelectric disk and A pair of driver plates positioned at both ends of at least one piezoelectric disk, Equipped with, A transducer comprising at least one piezoelectric disk, the outer surface of which is wavy along the transverse direction connecting the two base surfaces of the piezoelectric disk.

2. A laminate of piezoelectric disks (24) in which metal conductive disks (16) are alternately stacked with metal conductive disks (16) in between. It also has, The converter according to claim 1.

3. The converter according to claim 2, wherein the corrugated outer surface of the piezoelectric disk is rounded.

4. The converter according to claim 2, wherein the corrugated outer surface of the piezoelectric disk is formed by corrugated portions that extend radially outward.

5. The transducer according to claim 2, wherein the corrugated outer surface of the piezoelectric disk is formed by corrugated portions that are directed radially inward.

6. The converter according to claim 2, wherein the corrugated outer surface is coated with an insulating coating.

7. The transducer according to claim 2, wherein each of the piezoelectric disks includes an opening that penetrates its interior, and the inner circumferential surface of the opening is wavy along the transverse direction connecting the two base surfaces of the piezoelectric disk.

8. The converter according to claim 7, wherein the corrugated inner surface is coated with an insulating coating.

9. The transducer according to claim 1, wherein at least one piezoelectric disk includes an opening that penetrates its interior, and the inner circumferential surface of the opening is wavy along the transverse direction connecting the two base surfaces of the piezoelectric disk.

10. The converter according to claim 9, wherein the inner circumferential surface is coated with an insulating coating.

11. The converter according to claim 1, wherein the outer surface is coated with an insulating coating.

12. A method for assembling a transducer for an ultrasonic welding machine, The arrangement involves placing at least one piezoelectric disc between the first driver plate and the second driver plate, and all of these within a jig, wherein at least one piezoelectric disc has at least one hole. Applying a liquid insulating coating to the inside of at least one hole in the piezoelectric disk while at least one piezoelectric disk, as well as the first and second driver plates, are fixed by a jig, Inserting bolts into holes in the first driver plate and holes in at least one piezoelectric disk, and tightening the bolts into screw holes in the second driver plate to create an assembled transducer, inserting, A method that includes [a certain feature].

13. The method according to claim 12, wherein at least one piezoelectric disk has an outer surface having an arc length between metal conductor disks that is greater than the thickness of at least one piezoelectric disk.

14. The method according to claim 13, further comprising applying a liquid insulating coating to the outer surface of the assembled transducer.

15. The method according to claim 13, wherein the outer surface of at least one piezoelectric disk has a corrugated surface.

16. The method according to claim 12, wherein the hole in at least one piezoelectric disk has an inner circumferential surface having an arc length greater than the thickness of at least one piezoelectric disk.

17. The method according to claim 16, wherein the inner circumferential surface of the hole in at least one of the piezoelectric disks has a corrugated surface.

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