WO2001000388A1

WO2001000388A1 - Ultrasound welding apparatus

Info

Publication number: WO2001000388A1
Application number: PCT/US2000/017429
Authority: WO
Inventors: Peter T. Lee; Andrew Kelley, Iii
Original assignee: Virtual Ink Corporation
Priority date: 1999-06-28
Filing date: 2000-06-23
Publication date: 2001-01-04
Also published as: AU5636500A

Abstract

An ultrasound welding component (118) is disclosed. One embodiment of the component includes a weld region about which an ultrasound weldable material (140) may be wrapped into a loop. The weld region has an elliptical cross-section and includes a weld zone consisting of recesses positioned on opposing sides of a weld area. The configuration of the weld region causes the loop of weldable material to develop a more circular shape than the elliptical cross-section of the weld region.

Description

ULTRASOUND WELDING APPARATUS

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an ultrasound welding component for welding an ultrasound weldable material into a loop and more particularly for welding an ultrasound transmitting material into a loop shaped ultrasound transducer.

Description of Related Art

Ultrasound welding refers to the technique of using sonic or ultrasonic vibrations to form a weld between ultrasound weldable materials. A typical ultrasound welding system includes an ultrasound welding tool for producing the sonic or ultrasonic vibrations and a surface where the ultrasound weldable materials are positioned. In operation of the system, the ultrasound welding tool is used to compress the ultrasound weldable materials against the surface. This compression generally results in the formation of an ultrasound weld between the sections of ultrasound weldable material which were compressed against the surface.

There is a need for improved methods and components for performing ultrasound welding.

SUMMARY OF THE INVENTION

The invention relates to ultrasound welding components. According to one embodiment, the component includes a weld region about which an ultrasound weldable material may be wrapped. The weld region includes a weld zone consisting of recesses positioned on opposing sides of a weld area. The recesses and weld area have widths selected such that an ultrasound source compressing overlapping sections of the ultrasound weldable material against the weld area forms a weld having a width which is narrower than a sum of the widths of the recesses and the weld area. The component also includes a mechanism which immobilizes the ultrasound weldable material relative to the weld zone.

According to another embodiment, the component includes a weld region about which an ultrasound weldable material may be wrapped, the weld region including a geometric configuration; and a weld zone forming a portion of the weld region, the weld zone having an elliptical curvature. According to yet another embodiment, the component includes a weld region about which an ultrasound weldable material may be wrapped; and a weld zone forming a portion of the weld region, the weld zone being adjacent to overlapping sections of the ultrasound weldable material, the weld zone having a geometric configuration selected to cause the ultrasound weldable material to develop a more circular cross-section after removal of an ultrasound source. In one preferred embodiment, the geometric configuration is elliptical in shape.

The invention also relates to ultrasound welding apparatuses which include an ultrasound welding component according to the present invention. The welding component also includes a mechanism which immobilizes the ultrasound weldable material relative to the weld zone. The ultrasound welding apparatus further includes an ultrasound source positionable opposite the weld area.

In one embodiment, the ultrasound welding apparatus includes a weld region about which an ultrasound weldable material may be looped; a weld zone forming a portion of the weld region; and a hard-stop aligned to stop an ultrasound source at a predetermined height above the weld zone.

The invention also relates to methods for forming a weld in an ultrasound weldable material.

According to one embodiment, the method includes providing a welding component having a weld region with a weld zone consisting of recesses positioned on opposing sides of a weld area. The method also includes wrapping the ultrasound weldable material around the weld region with sections of the ultrasound weldable material overlapping one another adjacent to the weld area and contacting the overlapping sections of the ultrasound weldable material with an ultrasound source. According to another embodiment, the method includes providing a welding component with a weld region having a weld zone, the weld zone having an elliptical curvature; wrapping the ultrasound weldable material into a loop about the weld region with sections of the ultrasound weldable material overlapping one another adjacent to the weld zone; and applying an ultrasound source to the overlapping sections.

According to another embodiment, the method includes looping an ultrasound weldable material on a weld region of an ultrasound welding component to form overlapping sections of the ultrasound weldable material adjacent to a weld zone of the weld region; delivering an ultrasound source to the overlapping sections to form a weld using an ultrasound source, wherein a separation between the weld zone and the ultrasound source during welding is controlled by a hard-stop.

According to another embodiment, a method is provided for forming a weld on an ultrasound weldable material. The method includes providing a welding component with a weld region having a weld zone, where the weld zone has an elliptical curvature. The method includes wrapping the ultrasound weldable material into a loop about the weld region with sections of the ultrasound weldable material overlapping one another adjacent to the weld zone. The method also includes applying an ultrasound source to the overlapping sections, and causing the loop of the ultrasound weldable material to become more circular by removing the ultrasound source being applied to the overlapping sections.

In another embodiment, a method for forming a weld on an ultrasonic weldable material is provided. The method includes looping an ultrasound weldable material on a weld region of an ultrasound welding component to form overlapping sections of the ultrasound weldable material adjacent to a weld zone of the weld region. The method further includes delivering an ultrasound source to the overlapping sections, where the ultrasound source reduces a thickness of the overlapping sections. The method further includes providing a hard-stop on the ultrasound welding component to stop the ultrasound source from reducing the thickness of the overlapping sections once the thickness of the overlapping sections is reduced to a differential height of the hard-stop relative to the weld zone.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1A is a perspective view of a welding component which includes a weld region.

Figure IB is a cross section of the welding component illustrated in Figure 1A. Figures 2 A-2G illustrate a method for using a welding component.

Figure 2 A illustrates a band of material being wrapped around a weld region of a component.

Figure 2B illustrates a band of material wrapped entirely around a weld region of a welding component. Figure 2C is a sideview of a band of material wτapped around a weld region such that one section of the band of material overlaps another section of the band of material.

Figures 2D and 2E illustrate overlapping sections of a band of material being contacted with an ultrasound source. Figure 2F is sideview of an apparatus which includes a welding component and an ultrasound source.

Figure 2G illustrates a loop of ultrasound weldable material being removed from the welding component.

Figure 3 is a cross section of a welding component looking along the longitudinal axis of the welding component. Figure 4A illustrates a welding collar which is removable from an operating end of the welding component.

Figure 4B illustrates a welding collar having closed recesses.

Figure 4C illustrates a welding collar having open recesses. Figure 5A illustrates a welding component having a receiving trench configured to receive the welding collar.

Figure 5B illustrates a welding component with a welding collar positioned in a receiving trench.

Figure 6 A is a cross section of a welding component having a receiving trench and a welding collar having a coupling side positioned within the receiving trench.

Figure 6B is a cross section of the welding collar having a weld zone and a coupling side. The outer diameter of the coupling side is the same size as the diameter of the weld zone. Figure 6C is a cross section of the welding collar having a weld zone and a coupling side. The outer diameter of the coupling side is smaller than the diameter of the weld zone.

FIG. 7 is an isometric view of a component of an ultrasound welding apparatus including a weld region with an elliptical cross-section and a hard- stop, under an embodiment of the invention.

FIGS. 8A-8C illustrate a process in which the weld region of the component in FIG. 7 may be used to form weldable material into a loop with a substantially circular cross-section, under an embodiment of the invention.

FIG. 8A illustrate the weldable material looped or wrapped around the weld region of the component, with the ultrasound source to be applied.

FIG. 8B illustrates the weldable material being welded in a hot state, under an embodiment of the invention.

FIG. 8C illustrate the loop of weldable material removed from the weld region and formed into a loop having a substantially circular cross-section. FIGS. 9A-9C illustrate use of an ultrasound source with the hard-stop of the component of FIG. 7, under an embodiment of the invention. FIG. 9A illustrates the ultrasound source being applied to overlapping sections of weldable material wrapped around the weld region of the ultrasound welding component.

FIG. 9B illustrate the ultrasound source beginning deformation of the weldable material.

FIG. 9C illustrate the ultrasound source being stopped from further deformation of the weldable material by the hard-stop.

DETAILED DESCRIPTION

The present invention relates to welding components, apparatuses, and methods for operating welding components. The welding component includes a weld region with a weld zone consisting of a weld area. A piece of an ultrasound weldable material may be wrapped around the weld region such that sections of the ultrasound weldable material overlap one another adjacent to the weld area. The welding component can also include an attachment mechanism for immobilizing the ultrasound weldable material with the overlapping sections adjacent to the weld area.

In operation of the welding component, an ultrasound source is used to compress the overlapping sections against the weld area. This compression can generate sufficient energy to form a weld within the overlapping sections which are adjacent to the weld area. Since the weld is formed in the overlapping sections of the band, the band is formed into a loop.

1. Use of Recesses to Control Weld Formation

According to one aspect of the invention, recesses are provided on opposing sides of the weld area to prevent the ultrasound source from compressing the ultrasound weldable material adjacent the weld area. By using the recesses to limit the amount of material that is compressed, the size of the weld that is formed can be controlled. As a result the present invention makes it possible to form smaller welds. For example, the welds formed typically have a width that is smaller than the combined widths of the recesses and the weld area.

The size and shape of weld area and the recesses can also be used to control the geometry of the weld that is formed. For instance, the component of the present invention is ideal for forming a loop of material with a very narrow linear weld. Specifically, a particular welding component can have recesses that define a narrow linear weld area. Because the welding component has a very narrow linear weld area geometry, the resulting weld formed with such a component will have a narrow linear weld shape.

An example of a loop shaped material where a narrow linear weld is desirable is as an ultrasound transducer in a transcription system such as the one described in U.S. Patent Applicant Serial No.: 09/273,921, filed March 9, 1999 which is incorporated herein by reference. In the typical transcription system, the ultrasound transducer may be a loop of ultrasound transmitting material encircling a stylus. The ultrasound transducer transmits the ultrasound signals used to track the position of the stylus relative to two or more ultrasound detectors. This tracking is performed by determining the time for the ultrasound signals to travel between the stylus and the ultrasound detectors. Because the loop encircles the stylus, the ultrasound signals emanate from the stylus 360 degrees around the stylus.

The loop shaped ultrasound transducers used with transcription systems are frequently formed by welding together overlapping sections of a band of an ultrasound transmitting material. If the weld is not formed properly, the weld can cause non-uniform transmission of ultrasound signals from different positions around the stylus. This non-uniform ultrasound transmission causes the position determined for the stylus to be a function of the angular orientation of the stylus relative to the detectors. Because a stylus is frequently rotated as it is used, this effect is not desirable. However, the effect can be reduced by using the welding component of the present invention to weld a band of an ultrasound transmitting material into a loop having a narrow weld. One type of ultrasound weldable material that is suitable for use with the present invention is PVDF. PVDF is known to emit ultrasound signals in response to application of a potential. Accordingly, a band of PVDF is ideal for forming the loop shaped ultrasound transducer for a transcription system. The perimeter of a loop created according to the present inventor can be controlled by selecting the size of the component used. Since the band of material is wrapped around the weld region before the band is welded into a loop, the perimeter of the loop formed are similar to the perimeter of the ultrasound welding component adjacent of the weld region. Accordingly, small perimeter loops can be created with an ultrasound welding component having a weld region with a small perimeter. Since loop shaped ultrasound transducers used with transcription systems frequently have small perimeters, the ultrasound welding component of the present invention is ideal for creation of these small perimeter loops. Figure 1A illustrates a welding component 10 according to the present invention. The component includes a rigid body 12 with a mounting region 14 having one or more flat sections 16 for mounting the component 10 in a clamping device. The clamping device can be coupled with the flat sections 16 so as to prevent the component 10 from rotating within the clamping device. Suitable materials for construction of the welding component include, but are not limited to, iron and steel.

The component 10 also includes a weld region 18 about which a band of ultrasound weldable material can be wrapped. The weld region includes a weld zone 19 consisting of a plurality of recesses 20 positioned on opposing sides of a weld area 22. The weld region 18 also includes a plurality of vacuum ports 24 positioned on opposing sides of the weld area 22. The vacuum ports 24 preferably have a diameter between 0.01 and 0.03 inches.

Figure IB is a cross section of the component 10 illustrated in Figure 1 A. The vacuum ports 24 on the weld region 18 are in fluid communication with a lumen 26 extending through the longitudinal length of the component 10. The lumen 26 can be coupled with a vacuum source which can be used to draw a vacuum through the vacuum ports 24. The vacuum pulled through the vacuum ports 24 can be used to immobilize a band of material relative to the weld region 18.

Figures 2A-2G illustrate a method for using the component 10. In Figure 2 A a vacuum is drawn through the lumen 26 within the component 10 and a band 28 of ultrasound weldable material is wrapped around the weld region 18 of the component 10. Suitable ultrasound weldable materials include, but are not limited to, PVDF. The band 28 is positioned on the weld region 18 so a section of the band 28 extends over the weld area 22. The band 28 is then wrapped around the weld region 18 so the band 28 covers the vacuum ports 24 positioned to one side of the weld area 22. The vacuum pulled through the vacuum ports 24 immobilizes the band 28 relative to the weld area 22. As the band 28 is wrapped around the weld region 18, the band 28 is kept in contact with a weld region edge 30 to ensure correct placement of the band 28 relative to the weld region 18.

As illustrated in Figure 2B, the band 28 is eventually wrapped around the weld region 18 so it covers the vacuum ports 24 on both sides of the weld area 22. The vacuum pulled through the vacuum ports 24 immobilizes the band 28 relative to the weld region 18. Although the vacuum ports 24 serve as an attachment mechanism in Figures 2A and 2B, other attachment mechanisms can be used with the component 10. Other suitable attachment mechanisms include, but are not limited to, electrostatic mechanisms, releasable adhesives, contact strips, and other high friction materials. The attachment mechanism can also be a function of the material to be welded. For instance, when the material has a metal component 10, the attachment mechanism can be magnets positioned around the weld zone 18. Once the band 28 is wrapped around the weld region 18, the band 28 can be manipulated to move as much of the band 28 as possible into contact with the weld region edge 30. The proximity of the band 28 to the weld region edge 30 helps to ensure consistent placement of each band 28 relative to the weld region 18. Figure 2C is a sideview of the component 10 looking down the longitudinal axis of the component 10 of Figure 2B as illustrated by the arrow labeled A. Sections of the band 28 overlap one another adjacent to the weld area 22. Similarly, sections of the band 28 overlap one another adjacent to the recesses 20.

Figures 2D and 2E illustrate an ultrasound source 34 compressing overlapping sections of the band 28 which are adjacent to the weld area against the weld area. The weld area 22 supports the adjacent overlapping sections of the band 28 during the compression. This support creates a pinch point 32 at the closest point between the ultrasound source 34 and the weld area 22. The maximum compression occurs at this pinch point 32 and decreases moving away from the pinch point 32. The compression generates enough energy within and around the pinch point 32 to form a weld 35 within the overlapping sections of the band 28 which are adjacent to the weld area 22. As described above, overlapping sections of the band 28 are also positioned adjacent to the recesses 20. The size of the recesses 20 are selected to reduce the support provided to the adjacent overlapping sections during compression of the overlapping sections adjacent to the weld area 22. The reduced support yields a reduced amount of energy generation within the overlapping sections adjacent to the recesses 20 as compared to the energy generation within the overlapping sections adjacent to the weld area 22. The reduced energy generation limits the formation of the weld 35 within the overlapping sections which are adjacent to the recesses 20. As a result, the weld 35 is primarily formed in the overlapping sections which are adjacent to the weld area 22 although portions of the weld 35 can be formed in the overlapping sections adjacent to the recesses 20. Because the weld 35 is primarily formed in the overlapping sections adjacent to the weld area 22, the weld 35 has a geometry which is similar to the geometry of the weld area 22.

The geometry of the weld area 22 can be altered in order to alter the geometry of the weld 35. For instance, when the component 10 is used to form a band 28 of ultrasound transmitting material into a loop shaped ultrasound transducer for use with a transcription system, the weld 35 is preferably small to prevent the weld 35 from affecting the transmitting characteristics of the ultrasound transmitting material. The small weld is provided by using a welding component 10 with a narrow weld area 22. Suitable ultrasound sources 64 include, but are not limited to, an ultrasound hammer configured to vibrate at 20, 40, and 60 kHz. As illustrated, the direction of vibration is preferably perpendicular to the plane of the band 28 at the pinch point 32. The ultrasound source 34 can be handheld. Alternatively, an ultrasound welding apparatus can have a structure which includes both the ultrasound source 34 and the component 10 as illustrated in Figure 2F. The structure is designed so the ultrasound source 34 can be mechanically moved relative to the band 28 of ultrasound weldable material. Accordingly, the ultrasound source 34 can be moved into and out of contact with the band 28 of material with the force, direction and duration required to form the ultrasound weld 35. The apparatus can be computer controlled to minimize the amount of operator error associated with creating the weld 35.

Once the weld 35 has been formed in a band 28 of ultrasound weldable material, the loop can be removed from the weld region 18 as illustrated in Figure 2G. The loop can have one or more tag ends 86 extending beyond the weld. These tag ends can be removed with a cutting technique which is appropriate for the ultrasound weldable material. Preferably, the length of the material is selected such that tag ends are not formed, thereby obviating a removal step.

As described, the features of the weld region 18 are selected so the weld has a geometry which is similar to the geometry of the weld area. Figure 3 illustrates the features of the weld region in a cross sectional view of a component 10 looking down the longitudinal length of the component 10 at the point labeled A in Figure 1. The weld region has a perimeter labeled P. When the component 10 is used to form a band of ultrasound transmitting material into a loop shape ultrasound transducer for use with a transcription system, the perimeter of the weld region is preferably less than 1.75 inches, more preferably between 0.75 and 1.75 inches, and most preferably between 1 and 1.75 inches. As illustrated in Figure 3, the weld area has a surface 36 labeled S. The surface 36 is preferably curved. Examples of curved surfaces include, but are not limited to, elliptical and circular.

The weld area may have an angular width labeled α. An increased angular width α results in an increased weld area 22 and accordingly a wider weld. When the component 10 is used to form a loop shaped ultrasound transducer for use with a transcription system, the angular width, α, is preferably less than about 0.1 degrees and more preferably between about 0.01 and 0.1 degrees and most preferably between about 0.03 and 0.06 degrees. Similarly, the weld area can also have an width labeled W_WA. When the component 10 is used to form a loop shaped ultrasound transducer for use with a transcription system, the width W_WA is preferably less than 0.03 includes, preferably between 0.005 and 0.03 inches and more preferably between 0.005 and 0.015 inches. When a very narrow weld is desired, the width of the weld area, W_WA, is decreased.

The recesses 20 have an angular width labeled β. When the component 10 is used to form a loop shape ultrasound transducer for use with a transcription system, the angular width, β, is preferably less than about 0.3 degrees, more preferably between 0.1 and 0.3 degrees, most preferably 0.25 degrees. The recesses also have a width labeled W_R. When the component 10 is used to form a loop shape ultrasound transducer for use with a transcription system, the width, W_R, is preferably less than about 0.05 inches, more preferably between 0.02 and 0.05 inches, and most preferably between 0.02 and 0.04 inches.

The weld region 18 can be integral with the rigid body 12 or can be included on a welding collar 37 which slides over the rigid body 12 as illustrated in Figure 4 A. The rigid body 12 can also include vacuum ports 24. These vacuum ports 24 are aligned with the vacuum ports 24 on the welding collar 37 when the welding collar 37 is positioned on the rigid body 12. Once a desired position of the welding collar 37 relative to the rigid body 12 has been achieved, a fastener, such as a set screw 38, can be engaged to retain the welding collar 37 in place on the rigid body 12. An alternative fastener can include complementary threads on both the welding collar 37 and the rigid body 12. These complementary threads can be used to screw the welding collar 37 on and off the rigid body 12.

When the weld region 18 is included in a welding collar 37 the recesses 20 can be indentations in the welding collar 37 or can be apertures extending through the welding collar 37. Because the recesses 20 can be formed in the welding collar 37, the recesses 20 do not need to be formed in the rigid body 12. As a result, a number of different welding collars 37 can be used with a single rigid body 12. These welding collars 37 can have different perimeters for forming loops of different sizes. Further, different welding collars 37 can have weld areas 22 with different sizes. Since the weld formed with the component 10 has a geometry which is similar to the geometry of the weld area 22, a single rigid body 12 can be used with different welding collars 37 to provide different geometry welds.

Positioning a welding collar 37 on the rigid body 12 causes an abutting side 40 of the welding collar 37 to abut the weld region edge 30. The welding collar 37 can have closed recesses 44 as illustrated in Figure 4B or can have open recesses 46 which are open on the abutting side 40 of the welding collar 37 as illustrated in Figure 4C. The open recesses 46 permit the weld area 22 to abut the weld region edge 30. As a result, the straight shape of the weld area 22 is retained and is consistent at the intersection of the weld area 22 and the weld region edge 30.

An alternative component 10 which can be used to provide a weld area 22 with a consistent shape adjacent to the weld region edge 30 is illustrated in Figures 5A and 5B. The weld region edge 30 includes a receiving trench 48 configured to receive the abutting side 40 of a welding collar 37 positioned on the rigid body 12. When the welding collar 37 includes closed recesses 44, the receiving trench 48 can be deep enough to engulf the closed ends as illustrated in Figure 5B. Enclosure of these ends allows the weld area 22 to maintain a geometry adjacent to the weld region edge 30 which is consistent with the geometry of the remaining portions of the weld area 22.

Figure 6 A provides a cross section of a component 10 with a welding collar 37 positioned on the rigid body 12. The abutting side 40 of the welding collar 37 has a coupling side 50 with a geometry which is complementary to the geometry of the receiving trench 48. These complementary geometries permit the coupling side 50 to be positioned within the receiving trench 48. The coupling side 50 can have an external side 52 which sits flush with the weld region edge 30 when the coupling side 50 is positioned within the receiving trench 48. As a result, the external side 52 of the coupling side 50 becomes a part of the weld region edge 30.

Figures 6B and 6C illustrate additional welding collar 37 embodiments. The coupling sides 50 illustrated in Figure 6 A, 6B and 6C each have the same sized inner diameter D, and the same sized outer diameter D₂, while the weld regions 18 on each welding collar 37 have different diameters. Because the coupling sides 50 have the same dimensions and the coupling side 50 is positioned within the receiving trench 48, each welding collar 37 can be used with the same rigid body 12. As a result, the coupling sides 50 allow welding collars 37 with different sized weld regions 18 to be used with a single rigid body 12.

To encourage consistent positioning of the welding collar 37 relative to the rigid body 12, the welding collar 37 and rigid body 12 can include one or more alignment mechanisms. For instance, the welding collar 37 can include one or more tabs 60 as illustrated in Figure 6B. The welding collar 37 can include holes (not illustrated) which are complementary to the tabs 60. When the welding collar 37 is positioned on the rigid body 12 the welding collar 37 can be rotated until the tabs 60 fit into the holes. The welding collar 37 will not be received within the receiving trench 48 until the welding collar 37 has a particular angular orientation relative to the rigid body 12. As a result, each time a particular welding collar 37 is used with a particular rigid body, the welding collar 37 will be positioned on the rigid body 12 with a consistent angular orientation. This angular orientation can ensure alignment between vacuum ports 24 on the welding collar 37 and vacuum ports 24 on the weld region 18. Although the above discussion discloses weld areas which are straight, the weld area 22 can have any number of geometries including curved, zigzagged and other irregular geometries. In addition, the component 10 is not limited to welding pieces of material into loops as discussed above. For instance, the component 10 can be used to weld two different pieces of material together. Further, the components, apparatuses and methods according to the present invention can be used to form ultrasound welds in materials to be used in applications other than ultrasound transducers and transcription systems.

Elliptical Weld Region

According to another aspect of the invention, the geometry of the weld region is used to cause a loop of ultrasound weldable material to be formed which has a more circular cross-section. In one particular embodiment, the weld region has an elliptical shape which fosters this desired result. As in the previous embodiment, the welding component includes a weld region about which an ultrasound weldable material is wrapped. In this embodiment, the weld component may or may not have recesses. A weld zone is provided on the weld region adjacent to where overlapping sections of the weldable material are to be welded together. An ultrasound source is applied to weld the overlapping sections of the weldable material together.

The ultrasound source heats the weldable material. Once the ultrasound source is removed, the weldable material cools and changes shape. When the ultrasound source is applied, the weld region is shaped so as to allow the weldable material to subsequently cool and form a loop with a more circular cross-section.

A method is also provided for forming a weld on an ultrasound weldable material. The method includes providing a weld region having a weld zone with an elliptical curvature. The elliptical curvature includes any arc-length having a curve that can be characterized by more than one radius of curvature. The weld zone may form an arc-length portion of the weld region where end points of the arc-length each have a radius of curvature that is different than a radius of curvature of a point intermediate to the end points. In one embodiment, the weld region includes an elliptical cross-section, and the weld zone is an arc-length forming a peripheral surface of the weld region. The weldable material is wrapped into a loop about the weld region, with overlapping sections of the weldable material being formed adjacent to the weld zone. The ultrasound source is then applied to the overlapping sections.

In an embodiment, the loop of the weldable material is caused to become more circular when the ultrasound source is removed from weldable material. This may be accomplished by allowing the weldable material to cool after the ultrasound source is removed.

3. Use of a Hard Stop to Control Weld Thickness

According to another aspect of the invention, a hard stop is used to control the thickness of ultrasound welds that are formed. It is noted that the recesses described in Section 1 , the elliptical cross section described in Section 2, and hard stop described in this section may each be used alone or in different combinations with each other.

According to this aspect of the invention, an ultrasound welding apparatus is provided which includes a weld region about which weldable material is looped. The weldable material is deformable with the application of the ultrasound source. The apparatus includes a weld zone that forms a portion of the weld region. The weld zone is adjacent to the overlapping sections of the weldable material. The apparatus also includes a hard-stop. The hard-stop is positioned adjacent to the weld zone to control the positioning of the ultrasound source relative to the weldable material. This allows welds of controlled thicknesses to be formed, the thicknesses being governed by the relative height of the hard-stop to the weld zone.

Also according to this aspect of the invention, a method for forming a weld on an ultrasound weldable material is provided which includes looping an ultrasound weldable material on a weld region of an ultrasound welding component to form overlapping sections of the ultrasound weldable material adjacent to a weld zone of the weld region; and delivering an ultrasound source to the overlapping sections to form a weld using an ultrasound source, wherein a separation between the weld zone and the ultrasound source during welding is controlled by a hard-stop

The use of an elliptically shaped weld region, in combination with a hard stop, will now be described in relation to FIGS. 7-9.

FIG. 7 is a welding component 110. The welding component 110 includes a mounting region 114, including a flat section 116. The flat section 116 is used to clamp the weld component to the ultrasound source 28 (FIG. 2D). The mounting region 114 includes a hard-stop 150 and a weld region 118. Hard-stop 150 is a flat surface positioned adjacent to the weld region 118.

As illustrated, the weld region 118 of welding component 1 10 may have an elliptical cross-section. The weld region 118 includes a rigid body 112 extending from a front face 103 of the mounting section 114. The front face 103 forms a shoulder on weld region 118. When weldable material 140 is wrapped about the weld region 118, the weldable material may be easily aligned along rigid body 112 by pushing the weldable material against the front face 103. The elliptical cross-section of the weld region 118 includes characteristics of a short radius a, and a long radius b. A plurality of vacuum ports 124 may be distributed on the weld region 118. As with previous embodiments, the vacuum ports 124 extend to a lumen in which a vacuum source may be applied. A vacuum force may be extended through the vacuum ports 124 to retain the ultrasound weldable material against the weld region 118. The vacuum ports release an audible differential when the weldable material 140 is wrapped around the weld region. The vacuum ports 124 are disposed so that if the weldable material 140 is pushed completely against the front face 103, all of vacuum ports 124 are covered. If the weldable material is not pushed completely against the front face 103, the audible difference is detectable.

As can be seen, weld zone 119 includes an elliptical curvature with a tangential plane that is parallel with hard-stop 150. Preferably, the weld region 118 includes an elliptical cross-section to define the curvature of the weld zone 119. As illustrated, the hard-stop 150 is positioned slightly above the weld zone, that height difference controlling the resulting thickness of the weld. The height difference is preferably about the thickness of the weldable material. In one embodiment, the height difference is 0.001 inches.

FIGS. 8A-8C illustrate a process by which the elliptical geometric configuration of the weld region 118 can be used to form a circular loop of ultrasound weldable material 140. In FIG. 8 A, weldable material 140 is wrapped about the weld region 118 so as to form a loop having a substantially elliptical cross-section. The overlapping sections 132 are radially aligned with weld zone 119. The ultrasound source is applied to the overlapping sections 132. When the ultrasound source 28 is applied, the weldable material 140 is heated. The portion of the weldable material 140 that is melted is with the weld zone 119. In FIG. 8B, the loop of ultrasound weldable material 140 is removed from the weld region 118. The portions of the weldable material 140 over the weld zone begins to re-solidify to form a weld 144 where the overlapping sections 132 previously existed. The loop of ultrasound weldable material 40 initially includes an elliptical geometric configuration to match the configuration of the weld region 118.

FIG. 8C illustrates the loop of weldable material after it has cooled. The re-solidified weldable material shrinks to form the weld 144. The formation of weld 144 alters the geometric configuration from when the loop of weldable material was first wrapped about the weld region 118. In the embodiment shown, the weld region's characteristic elliptical properties are selected so that the resulting loop of weldable material in the cool state has a substantially circular cross-section. Thus, the radius of curvature of the resulting loop of weldable material is approximately uniform across the loop of weldable material 140.

FIGS. 9A-9C illustrate an embodiment in which hard-stop 150 controls the extend of deformation of weldable material 140 over weld zone 119. The hard-stop 150 is a laterally adjacent to weld zone 119. The hard-stop 150 forms a stepped configuration with respect to the portion of the weld region 118 representing the weld zone 119. The distance between tangential planes of the hard-stop 150 and the weld zone 119 corresponds to a designated separation or height h. A separation or height between the weld zone 119 and the hard-stop 150 also refers to the designated thickness h of the stepped configuration.

In an embodiment, the designated thickness h is the thickness of one layer of the weldable material. This thickness may range between 0.0008" and 0.0012", and preferably about 0.001". FIG. 9A is a front view of ultrasonic welding component 110, illustrating the ultrasound source 28 being lowered onto overlapping sections of the weldable material 140. The overlapping sections are positioned on the weld zone 119.

FIG. 9B shows the ultrasound source beginning to weld the weldable material 140. The ultrasound source 28 heats the overlapping sections, causing deformation. The ultrasound source 28 is moved towards a surface corresponding to the weld zone 119 as the weldable material deforms. Thus, a thickness of the weldable material is reduced as the ultrasound source 28 is applied. The ultrasound source continues towards the surface of the weld region 118, reducing the thickness of the weldable material 140.

FIG. 9C illustrates the ultrasound source being stopped by the hard-stop 150. In an embodiment, the hard-stop 150 is aligned to contact a surrounding structure of the ultrasound source 28. The hard- stop ensures that the weldable material is not deformed past the height differential designated by the position of the hard-stop relative to the weld zone 119.

Advantages provided by hard-stop 150 include ensuring that weldable material is welded so as to deform into an optimal thickness. When two layers of weldable material are welded together, the optimal thickness corresponds to a thickness of one layer of the weldable material. Therefore, with overlapping sections, two layers of weldable material are welded to have a thickness corresponding to one layer of weldable material. Because the thickness of one layer of weldable material is about 0.001", the settings of most other welding machines is not consistent or accurate enough to achieve the 0.001".

In contrast, embodiments of the invention provide that the minimum separation or height h of the hard-stop relative to the weld zone 119 may be manufactured to be approximately 0.001". This allows subsequent welding processes to always produce overlapping sections that are welded together to have a thickness of one layer of weldable material. This is possible because the machining tolerances for forming the hard-stop to include the designated thickness h from the weld zone 119 is much more accurate than position settings on a device including an ultrasound source 28.

EXAMPLES Example 1

An ultrasound welding component having a cylindrically shaped weld region with a radius of 0.225 inches was used in conjunction with a 40 kHz ultrasound hammer to weld a band of PVDF into an loop shaped ultrasound transducer. The welding component had a weld area with a width of 0.1 inches (0.05 degrees) and recesses on opposing sides of the weld area with a width of 0.3 inches (0.15 degrees). The ultrasound hammer was used to compress overlapping sections of the PVDF band against the weld area for 0.3 seconds to produce a loop of PVDF material having a weld with a width of about 0.1 inches. Example 2

In one embodiment, the weld region 118 includes an elliptical cross- section having a short radius a measuring 0.394", and a long radius b measuring 0.500". The ultrasound welding source welds overlapping sections of a loop of weldable material such as PVDF. After welding is complete, the resulting circular cross-section of the loop has a diameter of approximately 0.450".

While this example shows the ratio of a to b as being 0.788, other embodiments may vary this ratio. For example, the ratio of a to b may range between 0.5 and 0.9.

Further, the contraction properties of the weldable material 140 may be used to alter the geometric configuration of the weldable material into a desired shape. In one implementation, the geometric configuration of the weld region 118 may be elliptical, oval or another shape. After ultrasonic welding is complete, the weldable material 140 may be made to have a different short and long radii. For example, the weldable material 140 may be made to have an elliptical but more circular cross-section than weld region 118.

While the present invention is disclosed by reference to the preferred embodiments and examples detailed above, it is to be understood that these examples are intended in an illustrative rather than limiting sense, as it is contemplated that modifications and combinations will readily occur to those skilled in the art, which modifications and combinations will be within the spirit of the invention and the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A method for forming a weld on an ultrasound weldable material, the method comprising: providing a welding component with a weld region having a weld zone, the weld zone having an elliptical curvature; wrapping the ultrasound weldable material into a loop about the weld region with sections of the ultrasound weldable material overlapping one another adjacent to the weld zone; and applying an ultrasound source to the overlapping sections.

2. The method of claim 1, further comprising causing the loop of the ultrasound weldable material to become more circular by removing the ultrasound source being applied to the overlapping sections.

3. The method of claim 2, including configuring the weld zone so as to cause the loop of the ultrasound weldable material to become substantially circular after removing the ultrasound source applied to the overlapping sections.

4. The method of claim 1, wherein causing the loop of the ultrasound weldable material to become more circular includes cooling the ultrasound weldable material after removing the ultrasound source being applied to the overlapping sections.

5. The method of claim 4, wherein wrapping the ultrasound weldable material into a loop around the weld region includes wrapping the ultrasound material into the loop with an elliptical curvature, and wherein causing the loop of ultrasound weldable material to become more circular includes causing the loop of the ultrasound material to form a substantially circular cross-section.

6. The method of claim 1 , wherein providing a welding component with a weld region includes providing the weld region to include an elliptical cross- section.

7. The method of claim 1, wherein providing a welding component with a weld region includes providing the weld region to include an elliptical peripheral portion over at least the weld zone.

8. An ultrasound welding component comprising: a weld region about which an ultrasound weldable material may be wrapped; the weld region including a geometric configuration; and a weld zone forming a portion of the weld region, the weld zone having an elliptical curvature.

9. The ultrasound welding component of claim 8, wherein a geometric configuration of the weld region causes the ultrasound weldable material to develop a more circular cross-section after removal of an ultrasound source that forms a weld on the ultrasound weldable material by compressing the overlapping sections against the weld zone.

10. The ultrasound welding component of claim 9, wherein the geometric configuration of the weld region forms the weld to have a width defining a non- circular arc-length while the ultrasound source is compressing the overlapping sections of the ultrasound weldable material.

11. The ultrasound welding component of claim 8, wherein the weld region has an elliptical cross-section.

12. The ultrasound welding component of claim 8, wherein the weld region includes a plurality of vacuum holes which extend to a lumen being applied a vacuum, the vacuum holes causing the ultrasound weldable material to be retained against the weld zone.

13. The ultrasound welding component of claim 12, wherein at least some of the plurality of vacuum holes are aligned to create an audible differential when the overlapping sections of the ultrasound weldable material are aligned with the weld zone.

14. The ultrasound welding component of claim 8, wherein the weld zone is provided on a welding collar which is detachable from the weld region.

15. An ultrasound welding component comprising: a weld region about which an ultrasound weldable material may be wrapped; and a weld zone forming a portion of the weld region, the weld zone being adjacent to overlapping sections of the ultrasound weldable material, the weld zone having a geometric configuration so that an ultrasound source that deforms overlapping sections of the ultrasound weldable material against the weld zone to form a weld subsequently causes the weld to form a more circular curvature.

16. The ultrasound welding component of claim 15, wherein the weld region includes an elliptical cross-section.

17. The ultrasound welding component of claim 15, wherein the weld region includes a plurality of vacuum holes which extend to a lumen being applied a vacuum, the vacuum holes causing the ultrasound weldable material to be retained against the weld zone.

18. The ultrasound welding component of claim 17, wherein at least some of the plurality of vacuum holes are aligned to create an audible differential when the overlapping sections of the ultrasound weldable material are aligned with the weld zone.

19. The ultrasound welding component of claim 17, wherein at least some of the plurality of vacuum holes are aligned to create an audible differential when the overlapping sections of the ultrasound weldable material are aligned with the weld zone.

20. An ultrasound welding apparatus for use with a device including an ultrasound source, the ultrasound welding apparatus comprising: a weld region about which an ultrasound weldable material may be looped; a weld zone forming a portion of the weld region; a hard-stop aligned to stop an ultrasound source at a predetermined height above the weld zone.

21. The ultrasound welding apparatus of claim 20, wherein the weld zone has a circular curvature.

22. The ultrasound welding apparatus of claim 20, wherein the weld region has an elliptical curvature.

23. The ultrasound welding apparatus of claim 20, wherein the hard-stop is a formation on a mounting structure of the ultrasound welding apparatus used to mount the ultrasound apparatus with the device containing the ultrasound source.

24. The ultrasound welding apparatus of claim 23, wherein the hard-stop is laterally offset relative to the weld zone.

25. The ultrasound welding apparatus of claim 24, wherein the height of the hard-stop above the weld zone ranges is between 0.0008 inches and 0.0012 inches.

26. The ultrasound welding apparatus of claim 20, wherein weld zone is defined on a welding collar which is detachable from the weld region.

27. A method for forming a weld on an ultrasound weldable material, the method comprising: looping an ultrasound weldable material on a weld region of an ultrasound welding component to form overlapping sections of the ultrasound weldable material adjacent to a weld zone of the weld region; delivering an ultrasound source to the overlapping sections to form a weld using an ultrasound source, wherein a separation between the weld zone and the ultrasound source during welding is controlled by a hard-stop.

28. The method of claim 27, wherein looping an ultrasound weldable material on a region of an ultrasound welding component includes forming a circular loop of ultrasound material on the region of the ultrasound welding component.

29. The method of claim 27, wherein looping an ultrasound weldable material on a region of an ultrasound welding component includes forming an elliptical loop of ultrasound material on the region of the ultrasound welding component.

30. The method of claim 29, further comprising causing the ultrasound weldable material to become more circular by stopping the ultrasound source from being applied to the overlapping sections.

31. The method of claim 27, wherein the minimum separation between the ultrasound source and the weld zone as controlled by the hard-stop is between 0.0008 and 0.0012 inches.