Transverse Sonotrode Design for Ultrasonic Welding

Abstract

The disclosed principles prevent damage to ultrasonic welding assemblies when a sonotrode assembly is subjected to rigorous work conditions. The disclosed principles “decouple” the transducer from the direction of working displacement, using a transverse mounting arrangement, and drive the welding assembly at the nodal region to take advantage of the Poisson Effect. In one embodiment, an exemplary system comprises an ultrasonic transducer configured to convert electricity to generate ultrasonic waves, wherein the waves propagate along a first direction from the transducer. In addition, such a system may comprise a sonotrode having at least one ultrasonic welding surface and configured to receive the generated waves. The sonotrode is configured to stretch and compress in a second direction, perpendicular to the first direction, based on corresponding peaks and valleys of the waves when propagating along the second direction thereby oscillating the welding surface for an ultrasonic welding process.

We claim: 
     
         1 . A system for ultrasonic welding of materials, the system comprising:
 an ultrasonic transducer configured to convert electricity to generate ultrasonic waves, wherein the waves propagate along a first direction from the transducer; and   a sonotrode having at least one ultrasonic welding surface and configured to receive the generated waves, the sonotrode further configured to stretch and compress in a second direction, perpendicular to the first direction, based on corresponding peaks and valleys of the waves when propagating along the second direction thereby oscillating the welding surface for an ultrasonic welding process.   
     
     
         2 . A system in accordance with  claim 1 , further comprising an anvil configured to receive the oscillations of the welding surface during ultrasonic welding of a material placed therebetween. 
     
     
         3 . A system in accordance with  claim 1 , wherein the welding surface comprises an anti-nodal region of the sonotrode, the sonotrode further configured to receive the generated waves at a nodal region. 
     
     
         4 . A system in accordance with  claim 3 , wherein opposing ends of the sonotrode comprise the nodal region, the system further comprising a second ultrasonic transducer configured to convert electricity to generate second ultrasonic waves, wherein the second waves propagate along the first direction from the second transducer such that the first and second waves are received at the nodal region of the sonotrode from corresponding opposing ends of the sonotrode. 
     
     
         5 . A system in accordance with  claim 1 , wherein the system comprises a rotary ultrasonic welding assembly, the sonotrode rotating about an axis extending along the first direction. 
     
     
         6 . A system in accordance with  claim 5 , the rotary assembly further comprising an anvil configured to receive oscillations from the welding surface during ultrasonic welding of a material placed therebetween, the anvil rotating in unison with the welding surface about an axis extending also along the first direction. 
     
     
         7 . A system in accordance with  claim 5 , wherein the sonotrode comprises two opposing welding surfaces. 
     
     
         8 . A system in accordance with  claim 1 , further comprising a booster coupled to the transducer and configured to alter amplitude of the generated waves while propagating along the first direction, the altered waves transmitted to the sonotrode. 
     
     
         9 . A system for ultrasonic welding of materials, the system comprising:
 an ultrasonic transducer configured to convert electricity to generate ultrasonic waves, wherein the waves propagate along a first direction from the transducer;   a sonotrode having at least one ultrasonic welding surface at an anti-nodal region and configured to receive the generated waves at a nodal region, the sonotrode further configured to stretch and compress in a second direction, perpendicular to the first direction, based on corresponding peaks and valleys of the waves when propagating along the second direction thereby oscillating the welding surface; and   an anvil configured to receive the oscillations of the welding surface for ultrasonic welding of a material placed between anvil and the welding surface.   
     
     
         10 . A system in accordance with  claim 9 , wherein opposing ends of the sonotrode comprise the nodal region, the system further comprising a second ultrasonic transducer configured to convert electricity to generate second ultrasonic waves, wherein the second waves propagate along the first direction from the second transducer such that the first and second waves are received at the nodal region of the sonotrode from corresponding opposing ends of the sonotrode. 
     
     
         11 . A system in accordance with  claim 9 , wherein the system comprises a rotary ultrasonic welding assembly, the sonotrode rotating about an axis extending along the first direction. 
     
     
         12 . A system in accordance with  claim 11 , the rotary assembly further comprising a rotary anvil rotating in unison with the welding surface about an axis extending also along the first direction. 
     
     
         13 . A system in accordance with  claim 11 , wherein the sonotrode comprises two opposing welding surfaces. 
     
     
         14 . A system in accordance with  claim 9 , further comprising a booster coupled to the transducer and configured to alter amplitude of the generated waves while propagating along the first direction, the altered waves transmitted to the sonotrode. 
     
     
         15 . A method for ultrasonic welding of materials, the method comprising:
 generating ultrasonic waves in a welding assembly;   transmitting the generated waves along the welding assembly in a first direction;   receiving the generated waves in a sonotrode, the waves entering the sonotrode while propagating along the first direction;   causing the received waves within the sonotrode to propagate along a second direction, perpendicular to the first direction; and   oscillating a welding surface of the sonotrode using peaks and valleys of the waves propagating in the second direction.   
     
     
         16 . A method in accordance with  claim 15 , further comprising applying the oscillations of the welding surface to an anvil for ultrasonic welding of a material placed therebetween. 
     
     
         17 . A method in accordance with  claim 16 , further comprising altering amplitude of the generated waves while propagating along the first direction based on a composition of the material placed therebetween. 
     
     
         18 . A method in accordance with  claim 16 , further comprising altering amplitude of the generated waves while propagating along the first direction based on a thickness of the material placed therebetween. 
     
     
         19 . A method in accordance with  claim 15 , wherein the welding surface comprises an anti-nodal region of the sonotrode, and wherein the receiving the generated waves comprises receiving the generated waves at a nodal region of the sonotrode. 
     
     
         20 . A method in accordance with  claim 19 , further comprising rotating the sonotrode about an axis extending along the first direction, and rotating the anvil in unison with the welding surface about an axis extending also along the first direction. 
     
     
         21 . A method in accordance with  claim 15 , further comprising altering amplitude of the generated waves while propagating along the first direction based on a composition of material comprising the sonotrode. 
     
     
         22 . A method in accordance with  claim 15 , further comprising altering a frequency of the generated waves while propagating along the first direction based on a composition of material comprising the sonotrode. 
     
     
         23 . A method in accordance with  claim 15 , further comprising altering amplitude or frequency of the generated waves while propagating along the first direction based on a temperature of material comprising the sonotrode. 
     
     
         24 . A method in accordance with  claim 15 , wherein the nodal region of the sonotrode comprises opposing ends of the sonotrode, and wherein the generate waves are first generated waves, the first generated waves entering the sonotrode at a first end of the opposing ends of the sonotrode, the method further comprising:
 generating second ultrasonic waves in a second welding assembly;   transmitting the second generated waves along the second welding assembly in the first direction;   receiving the second generated waves in the sonotrode, the waves entering the sonotrode at a second end of the opposing ends of the sonotrode;   causing the second received waves within the sonotrode to propagate along the second direction; and   oscillating the welding surface of the sonotrode using peaks and valleys of both the first and second waves propagating in the second direction.   
     
     
         25 . A method for ultrasonic welding of packaging materials, the method comprising:
 placing a packaging material between an anvil and an ultrasonic welding assembly;   generating ultrasonic waves in the welding assembly;   transmitting the generated waves along the welding assembly in a first direction;   receiving the generated waves in a sonotrode, the waves entering the sonotrode while propagating along the first direction;   causing the received waves within the sonotrode to propagate along a second direction, perpendicular to the first direction;   oscillating a welding surface of the sonotrode using peaks and valleys of the waves propagating in the second direction; and   applying the oscillations of the welding surface to the anvil for ultrasonic welding of the packaging material placed therebetween.   
     
     
         26 . A method in accordance with  claim 25 , wherein the welding surface comprises an anti-nodal region of the sonotrode, and wherein the receiving the generated waves comprises receiving the generated waves at a nodal region of the sonotrode. 
     
     
         27 . A method in accordance with  claim 26 , further comprising rotating the sonotrode about an axis extending along the first direction, and rotating the anvil in unison with the welding surface about an axis extending also along the first direction, wherein the packaging material is advanced during the rotating of the sonotrode and anvil. 
     
     
         28 . A method in accordance with  claim 25 , further comprising altering amplitude of the generated waves while propagating along the first direction, the altered waves transmitted to the sonotrode. 
     
     
         29 . A method in accordance with  claim 28 , wherein altering the amplitude of the generated waves while propagating along the first direction comprises altering the amplitude based on a composition of the packaging material. 
     
     
         30 . A method in accordance with  claim 28 , wherein altering the amplitude of the generated waves while propagating along the first direction comprises altering the amplitude based on a thickness of the packaging material. 
     
     
         31 . A method in accordance with  claim 28 , wherein altering the amplitude of the generated waves while propagating along the first direction comprises altering the amplitude based on a composition of material comprising the sonotrode. 
     
     
         32 . A method in accordance with  claim 25 , further comprising altering a frequency of the generated waves while propagating along the first direction based on a composition of material comprising the sonotrode. 
     
     
         33 . A method in accordance with  claim 25 , further comprising altering amplitude or frequency of the generated waves while propagating along the first direction based on a temperature of material comprising the sonotrode. 
     
     
         34 . A method in accordance with  claim 25 , wherein the nodal region of the sonotrode comprises opposing ends of the sonotrode, and wherein the generate waves are first generated waves, the first generated waves entering the sonotrode at a first end of the opposing ends of the sonotrode, the method further comprising:
 generating second ultrasonic waves in a second welding assembly;   transmitting the second generated waves along the second welding assembly in the first direction;   receiving the second generated waves in the sonotrode, the waves entering the sonotrode at a second end of the opposing ends of the sonotrode;   causing the second received waves within the sonotrode to propagate along the second direction; and   oscillating the welding surface of the sonotrode using peaks and valleys of both the first and second waves propagating in the second direction.