Ultrasonic welding and welding horn having indenter

#The present disclosure generally relates to welding and more specifically to techniques for ultrasonic welding, as well as to a welding horn, which are particularly useful for joining polymeric composite components.

#Ultrasonic welding may be used to join polymeric and/or metal components. In ultrasonic welding, the plastic or metal components are clamped between a welding horn and an anvil. To weld using ultrasonic energy, high-frequency vibrations are applied to the components to be joined by a high frequency vibration of the horn. The horn, or sonotrode, is a tool that creates ultrasonic vibrations that are applied to a workpiece or material such as for welding, machining, or mixing. In the case of ultrasonic welding, component joining occurs as the result of applied mechanical force and heat generated at the interface between the components by the mechanical vibration.

#Delivering consistent weld quality using ultrasonic welding requires overcoming a number of challenges. Process variables including clamp load, vibration amplitude, and weld time must be set precisely and must take into consideration variations in stack height and material. With the welding of plastic, clamp forces must be kept low enough to avoid distortion of the components, while stiffer materials require higher clamp loads. If the clamp forces are too low or if misalignment occurs, insufficient weld formation may result.

#The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

#The drawings herein are schematic in nature and are not necessarily drawn to scale or representative of the distances or relationships between the elements shown.

#FIG. 1 is a schematic side view of a welding horn having a plurality of knurls and an indenter extending from an end face, in accordance with the principles of the present disclosure;

#The following detailed description is merely exemplary in nature and is not intended to limit the application and uses.

#Referring now to FIGS. 1-2, a welding horn, or sonotrode, for use in vibrational or ultrasonic welding, such as conventional ultrasonic welding or ultrasonic torsional welding, to weld a plurality of workpieces together, is illustrated and generally designated at 10. The welding horn 10 includes a shank 12 and a tip 14 disposed at an end 16 of the shank 12. The tip 14 has an end face 18, which may be slightly curved to define a relatively large radius of curvature R1. The tip 14 is configured to contact a workpiece and to transmit energy to the workpiece to perform a welding operation, which will be described in further detail below.

#Referring to FIGS. 1-3, a number of knurls 20 may be disposed on the end face 18. The knurls 20 may be disposed adjacent to one another and uniformly distributed on the end face 18 except where interrupted by an indenter 22. In the illustrated example, each knurl 20 is shaped as a diamond pyramid, or four-sided pyramid, having a base 24 and sloping sides 26 that end in a distal end 28 of the knurl 20. Thus, each distal end 28 is a pointed tip of the knurl 20, and the distal ends 28 are separated by grooves 30 between the knurls 20. Though the knurls 20 are illustrated as being arranged in a pattern of straight lines, side by side, the knurls 20 could alternatively be illustrated in other patterns, such as a staggered or annular pattern, by way of example. Further, although the knurls 20 are illustrated as four-sided pyramids, they could be other shapes, such as three-sided pyramids, conical, or another shape.