Closed-loop adjustment system and method for gap control and leveling of ultrasonic devices

An apparatus and method for leveling a bonding device and anvil in an assembly via a closed-loop control system is provided. The assembly includes an anvil, a bonding device positioned adjacent the anvil and configured to interact with the anvil to form the bonds on the web, and an actuator that enables adjustment of an orientation between the bonding device and the anvil. The assembly also includes a closed-loop control system configured to control operation of the actuator, with the closed-loop control system configured to monitor an operational parameter of the assembly indicative of interaction of the bonding device with the anvil, determine whether the bonding device is parallel or substantially parallel with the anvil based on the operational parameter, and when the bonding device is not parallel or substantially parallel with the anvil, cause the actuator to adjust the orientation between the bonding device and the anvil.

BACKGROUND OF THE INVENTION

The present invention relates to disposable garments and more specifically, to systems and methods for making disposable garments. More specifically, the invention relates to ultrasonic bonding of garment layers and to the control and adjustment of the spacing and angling between an ultrasonic horn and patterned anvil in an ultrasonic assembly.

Ultrasonic technology is used, among other technologies, to bond non-woven fabric garment layers, as an alternative to (or to reduce the use of) consumables such as adhesives or glue. Ultrasonic energy is concentrated at specific bond points where frictional heat bonds non-woven fabric of the garment layers. An ultrasonic bonding system contains at least one patterned anvil that communicates with at least one ultrasonic horn. The patterned anvil contains a predetermined pattern created by raised regions on the anvil. The ultrasonic horn contains an ultrasonic emitting assembly. Layers of non-woven fabric, which may or may not contain additional garment components, are passed between the patterned anvil and the ultrasonic horn. The layers contact the raised pattern on the patterned anvil. While in contact with the raised pattern, the layers pass through an ultrasonic emission created by the ultrasonic horn. The ultrasonic emission increases the vibrations of the particles in the non-woven garment, thus increasing the temperature of the particles in the non-woven garment. The increased temperatures of the garment particles in the multiple layers of non-woven fabric result in bonding of the multiple layers of non-woven fabric along the raised patterns of the patterned anvil.

The ultrasonic horn should ideally be maintained at a constant and predetermined distance from the layers of non-woven fabric over a cross-machine direction length of the ultrasonic horn. Methods to monitor and control the constant and predetermined distance over the cross-machine direction length of the ultrasonic horn have typically been performed manually by an operator loosening and tightening a series of bolts on the ultrasonic horn. The operator manually loosens the bolts, manually adjusts a gap, or distance, between the ultrasonic horn and the patterned anvil, and manually adjusts the level of the ultrasonic horn with respect to the patterned anvil. However, this method often results in an ultrasonic horn placement where the distance between the ultrasonic horn and the patterned anvil is not ideal. As a result of this non-ideal gap or distance, the layers of non-woven fabric will experience varied bonding conditions over the cross-machine direction length. Locations where the distance between the ultrasonic horn and patterned anvil may be less than ideal may result in a ‘blow-out’ phenomenon in which in the ultrasonic energy creates a hole through the layers of non-woven fabric. Locations where the distance between the ultrasonic horn and patterned anvil may be less than ideal may result in the layers of non-woven fabric not becoming bonded together.

Further, the leveling of the ultrasonic horn and the adjusting of the gap or distance between the ultrasonic horn and patterned anvil is not a singular event. Instead, the adjustment of the gap or distance requires multiple adjustments over the operation of the machine. Every time the gap or distance between the ultrasonic horn and patterned anvil is adjusted manually and/or the ultrasonic horn is leveled, the machine is unable to be run during the manual adjustment process.

Therefore, a need exists for an automated system and method for adjusting the gap, or distance, between the ultrasonic horn and patterned anvil and for performing leveling of the ultrasonic horn and/or the anvil into a parallel arrangement. A need further exists for such gap adjustment and leveling to be performed while the machine continues to run, with such gap adjustment and leveling being periodically performed during operation of the machine.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one aspect of the invention, an apparatus for forming bonds on a web includes an anvil, a bonding device positioned adjacent the anvil and configured to interact with the anvil to form the bonds on the web, and an actuator that enables adjustment of an orientation between the bonding device and the anvil. The apparatus also includes a closed-loop control system configured to control operation of the actuator, the closed-loop control system configured to monitor an operational parameter of the apparatus indicative of interaction of the bonding device with the anvil, determine whether the bonding device is parallel or substantially parallel with the anvil based on the operational parameter, and when the bonding device is not parallel or substantially parallel with the anvil, cause the actuator to adjust the orientation between the bonding device and the anvil.

In accordance with another aspect of the invention, a method for leveling a bonding device and anvil in an assembly via a closed-loop control system is provided. The method includes monitoring an operational parameter of the assembly indicative of interaction of the bonding device with the anvil and determining, based on the operational parameter, whether the bonding device and the anvil are parallel or substantially parallel. The method also includes controlling an actuator to adjust an orientation between the bonding device and the anvil when the bonding device and the anvil are determined to not be parallel or substantially parallel. The monitoring of the operational parameter and the operation of the actuator to adjust the orientation between the bonding device and the anvil is performed via a closed-loop control scheme.

These and other advantages and features will be more readily understood from the following detailed description of preferred embodiments of the invention that is provided in connection with the accompanying drawings.

DETAILED DESCRIPTION

Embodiments of the present invention provide for a method and apparatus for leveling of the ultrasonic horn and/or patterned anvil in an ultrasonic assembly into a parallel or substantially parallel arrangement and for adjusting the gap, or distance, between of the ultrasonic horn and the anvil.

With attention toFIGS. 1 and 2, a bonding apparatus or assembly10is illustrated, according to an embodiment of the invention. According to an exemplary embodiment, the bonding assembly10comprises an ultrasonic assembly that functions to ultrasonically form bonds on one or more web materials and/or elastics, and thus hereafter bonding assembly10is referred to as ultrasonic assembly10. It is recognized, however, that the bonding assembly10could alternatively be configured to perform other types of bonding, including thermal or pressure bonding, for example, and thus embodiments of the invention are not limited only to ultrasonic bonding.

As shown inFIGS. 1 and 2, the ultrasonic assembly10comprises at least one ultrasonic horn assembly12and at least one patterned anvil14(hereinafter “anvil14”), according to known constructions, along with a closed-loop control system16. The ultrasonic assembly10may be any of a number of known ultrasonic bonding or welding systems, such as a rotary anvil and an ultrasonic blade horn, also known as a sonotrode, which cooperate with each other to form bonds on one or more web materials and/or elastics (not shown) that is passed between the ultrasonic horn assembly12and anvil14. The ultrasonic horn assembly12and anvil14are positioned in a spaced relationship relative to one another to facilitate ultrasonically bonding the web materials/elastics. During the bonding process, the web layers are exposed to an ultrasonic emission from the ultrasonic horn assembly12that causes the particles in the web layers to vibrate. The ultrasonic emission or energy is concentrated at specific bond points where frictional heat fuses the web layers together without the need for consumable adhesives.

The ultrasonic assembly10may include a single ultrasonic horn assembly12in communication with a single anvil14, as shown inFIGS. 1 and 2. Alternatively, multiple ultrasonic horn assemblies12may be in communication with a single anvil14, a single ultrasonic horn assembly12may be in communication with multiple anvils14, or multiple ultrasonic horn assemblies12may be in communication with multiple anvils14in various arrangements.

As shown inFIGS. 1 and 2, the ultrasonic horn assembly12comprises an assembly holder18and an ultrasonic stack20of components, with the holder18mechanically coupled to the ultrasonic stack20. According to an exemplary embodiment, the ultrasonic stack20includes a converter22, a booster24, and a horn26. The converter22receives a high frequency AC current from the generator30indicative of a desired operation of the ultrasonic horn assembly12and transforms the signal into a mechanical vibration or ultrasonic emission. The ultrasonic emission is amplified via booster24and is transmitted to the horn26. Based on the interaction of the horn26and anvil14, the ultrasonic emission or energy is concentrated at specific bond points, where frictional heat fuses the web layers together. Booster24may be omitted in alternative embodiments.

The closed-loop control system16is configured to determine a leveling condition of the ultrasonic horn assembly12(i.e., of horn26) with respect to the anvil14. As can be seen inFIGS. 1 and 2, in a non-level condition (FIG. 1), a distance D1between the horn26and anvil14at a first location is different from a distance D2between the horn26and anvil14at a second location, while when in a level condition (FIG. 2), the distances D1, D2are equal or substantially equal to each other—i.e., a distance D3, such that the facing surfaces27,29of the horn26and anvil14are parallel (i.e., level) or substantially parallel with one another. As used herein, “substantially parallel” means parallel to within +/−5 degrees.

In the illustrated embodiment, closed-loop control system16comprises a programmable logic controller (PLC)28, a generator30, and an actuator32. The elements/components of the closed-loop control system16are in operable communication with each other, with the generator30in operable communication with the PLC28along a generator/PLC communication34, the generator30in operable communication with the ultrasonic horn assembly12along a high frequency cable or communication36, and the PLC28in operable communication with the actuator32along a PLC/actuator communication38. The generator30and PLC28function to monitor one or more operational parameters of the ultrasonic assembly10indicative of interaction of the ultrasonic horn assembly12with the anvil14and determine a condition of the ultrasonic horn assembly12, such as a leveling condition of the ultrasonic horn assembly12with respect to the anvil14. The PLC28then generates and transmits control signals to the actuator32based on the determination of the leveling condition, with the control signals controlling operation of actuator32.

The actuator32of the closed-loop control system is coupled to the assembly holder18to provide for movement and/or rotation thereof—and to thereby also cause movement or rotation of the ultrasonic stack20. The actuator32comprises a drive40, such as a servo motor, that operates to cause movement of an adjustment mechanism42—with the drive40coupled to the adjustment mechanism42via a linkage system44. The adjustment mechanism42that is driven by drive40may be any of a number of suitable mechanisms, such as an arrangement of a slide mechanism46and channel48(as illustrated inFIGS. 1 and 2), a rack and pinion device, rocker assembly, or threaded rod and plate assembly, according to embodiments of the invention. The repositioning of the ultrasonic stack20via operation of actuator32serves to adjust the orientation of the horn26relative to the anvil14, so as to provide for leveling of the horn26and the anvil14.

According to embodiments of the invention, operation of the actuator32to adjust positioning of the ultrasonic stack20is controlled based on a determination of a leveling condition of the horn26with respect to the anvil14. The determination of the leveling condition of the horn26and anvil14is performed by the PLC28based on the measurement of one or operational parameters associated with operation of the ultrasonic horn assembly12. According to various embodiments, the operational parameter(s) may be measured directly by the generator30, by a separate sensor included on cabling connecting the generator30to the ultrasonic horn assembly, or by other external sensors positioned on the horn or anvil.

In one embodiment, the generator30directly measures power values associated with, or correlated to, the interaction of the horn26with the anvil14. That is, in operation of ultrasonic horn assembly12, command signals are initially provided to converter22(from generator30) that are indicative of a desired ultrasonic emission to be output by horn26for forming bonds on the web layer(s) positioned between the horn26and the anvil14, with the converter22and (optional) booster24transforming the received command signals into a final output to the horn26that causes output of the ultrasonic emission. The resulting power or energy that is transferred to the web layer(s) for the formation of bonds is dependent on the arrangement of the horn26relative to the anvil14and may be measured by the generator30based on the outgoing current demanded by the horn26.

In operation, the generator30acquires a plurality of power readings that are indicative of the operation of the ultrasonic horn assembly12and of a leveling condition of the horn26with respect to the anvil14. The generator30provides those measurements to the PLC28for comparison thereof and determination of the leveling condition. More specifically, the PLC28compares a plurality of power readings in order to identify a maximum power value that corresponds to a level or parallel arrangement between the horn26and the anvil14.

In performing a method for leveling the horn26relative to the anvil14, the generator30begins by measuring a first power value with the horn26at a first position or orientation and providing those measurements to the PLC28. Subsequent to the measurement, the PLC28functions to operate the actuator32to reorient the horn26relative to the anvil14—with the actuator32causing the horn26to rotate in a first direction and to a second position. Upon reorienting the horn26to the second position, the generator30measures a second power value and provides those measurements to the PLC28. The PLC28then compares the second power value to the first power value and, if the second power value is greater than the first power value, the PLC28operates the actuator32to reorient the horn26relative to the anvil14—with the actuator32causing the horn26to continue rotating in the first direction and to a third position. This sequence of power measurements and rotation of horn26in the first direction continues until the measured power value at a new horn position is less than the measured power value at the previous horn position. When the new power value is less than the previous power value, PLC28operates the actuator32to rotate the horn26in a second direction (opposite the first direction), to return the horn26to the position where the larger power value was measured.

Conversely, if upon reorienting the horn26to the second position, the measured second power value is less than the first power value, the PLC28operates the actuator32to successively rotate the horn in the second direction to one or more new positions. At each position generator30monitors a new power value and provides those measurements to the PLC28. The PLC28compares each new power value to the previous power value. As long as the new power value is greater than the previous power value, PLC28continues to rotate the horn in the second direction. If the new power value is less than the previous power value, PLC28either maintains the horn26in the current position or operates the actuator32to rotate the horn26in the first direction, to return the horn26to the position where the larger power value was measured. This larger power value is referred to hereafter as the maximum power value.

In general, during a leveling or paralleling operation the PLC28will generate commands that operate the actuator32to continue to rotate the horn26in the same direction as long as a subsequent power value reading/measurement is greater than the previous power value reading/measurement, in order to search for a position or orientation of the horn26that provides maximum power—i.e., a level or parallel position. Upon a subsequent power value reading/measurement being less than the previous power value reading/measurement, the PLC28will flag the previous position as the level or parallel position and cause the horn26to stay in the current orientation or rotate back to the level or parallel position at which the maximum power value was measured. In an instance where the previous and subsequent power values are equal, PLC28may cause the horn26to stay in the current orientation. Accordingly, adjustment of the horn26from a non-level position (FIG. 1) to a position where surface27of the horn26is level/parallel with the facing surface29of the anvil14(FIG. 2) may be achieved.

While operation of the generator30is described above as measuring power values from the ultrasonic horn assembly12, it is recognized that generator30could alternatively measure other operational parameters, including capacitance, frequency, or amplitude, as non-limiting examples, in order to determine the leveling condition. Determination of the leveling condition with measurement of any of the parameters would be similar to the method described above, with the PLC28comparing a plurality of readings in order to identify a specified parameter value (e.g., maximum value) that corresponds to a level or parallel arrangement between the horn26and the anvil14.

Referring still toFIGS. 1 and 2, according to another embodiment, a dedicated induction sensor50(shown in phantom) positioned on or integrated into the high frequency cable36is used to monitor operation of the ultrasonic horn assembly12rather than the generator30performing this function. In such an embodiment, generator30still operates to provide command signals to converter22that are indicative of a desired ultrasonic emission to be output by horn26for forming bonds on the web layer(s) positioned between the horn26and the anvil14, with the converter22and (optional) booster24transforming the received command signals into a final output to the horn26that causes output of the ultrasonic emission. However, the generator30is not configured to directly measure or monitor power signals fed back from the ultrasonic horn assembly12, and thus a separate induction sensor50is employed to monitor operation of the ultrasonic horn assembly12. Such an induction sensor50may be used to retrofit an existing ultrasonic assembly8(and generator30) to enable the assembly8to perform a determination of the leveling condition of the horn26with respect to the anvil14.

In operation, induction sensor50measures electrical current values on the high frequency cable36in order to identify a power reading/value indicative of the interaction of the horn26with the anvil14, so as to provide for a determination of the leveling condition of the horn26with respect to the anvil14. The measured current values—and subsequently derived power values—are provided to the PLC28, where comparison of the power values is performed in order to determine the leveling condition. That is, the PLC28compares a plurality of power readings in order to identify a maximum current value that corresponds to a level or parallel arrangement between the horn26and the anvil14.

The method for leveling the horn26relative to the anvil14using induction sensor50is similar to that described above where power values are measured directly by generator30. The induction sensor50measures a first current/power value with the horn26at a first position or orientation and provides those measurements to the PLC28. Subsequent to the measurement, the PLC28functions to operate the actuator32to thereby reorient the ultrasonic horn26relative to the anvil14—with the actuator32causing the horn6to rotate in a first direction and to a second position. Upon reorienting of the ultrasonic horn assembly12to the second position, the induction sensor50measures a second current/power value and provides those measurements to the PLC28. The PLC28then compares the second current/power value to the first current/power value and, if the second current/power value is greater than the first current/power value, the PLC28operates the actuator32to reorient the ultrasonic horn26relative to the anvil14—with the actuator32causing the horn6to continue rotating in the first direction and to a third position. Conversely, if the second current/power value is less than the first current/power value, the PLC28then determines that the previous orientation of surface27of the horn26relative to the facing surface29of the anvil14was closer to parallel. The PLC28thus operates the actuator32to reorient the horn26relative to the anvil14—with the actuator32causing the horn26to rotate in a second direction (opposite the first direction) and back to the first position.

The embodiments described above and shown inFIGS. 1 and 2are directed to a system and method for adjusting and reorienting the ultrasonic horn assembly12in order to level the horn26and anvil14.FIGS. 3 and 4depict an alternative embodiment that includes a system and method for adjusting and reorienting the anvil14in order to level the horn26and anvil14using a closed-loop control system16that is in operable communication with an actuator52that provides for movement and/or rotation of the anvil14. The actuator52comprises a drive54, such as a servo motor, that operates to cause movement of an adjustment mechanism56—with the drive54coupled to the adjustment mechanism56via a linkage system58. The adjustment mechanism56may be any of a number of suitable mechanisms, such as an arrangement of a slide mechanism and channel (as illustrated inFIGS. 3 and 4), a rack and pinion device, rocker assembly, or threaded rod and plate assembly, according to embodiments of the invention. The repositioning of the anvil14via operation of actuator52serves to adjust the orientation of the anvil14relative to the horn26, so as to provide for leveling of the horn26and the anvil14.

According to embodiments of the invention, the actuator52is controlled to adjust positioning of the anvil14based on a determination of a leveling condition of the anvil14with respect to the horn26. As described above with regard to the embodiments inFIGS. 1 and 2, the generator30may measure power values indicative of the interaction of the horn26with the anvil14(or capacitance, frequency, or amplitude) or, alternatively, induction sensor50may measure current/power values indicative of the interaction of the horn26with the anvil14, in order to provide for a determination of the leveling condition of the horn26and the anvil14. The measured power/current values are provided to the PLC28, where comparison of the power/current values is performed in order to determine the leveling condition.

The method for leveling the anvil14relative to the horn26using the measured power or current values is essentially identical to those described above. The position and orientation of the anvil14is incrementally adjusted by actuator52responsive to a plurality of comparisons of the power/current readings by the PLC28, until the PLC28identifies a maximum power/current value that corresponds to a level or parallel arrangement between the horn26and the anvil14.

Referring now toFIGS. 5 and 6, according to another embodiment, one or more external sensors60,62may be provided in order to measure one or more operational parameters associated with operation of a bonding assembly10, for purposes of performing leveling in the assembly. In one embodiment, the external sensors60,62are used in an ultrasonic assembly10(as described below), but it is recognized that the external sensors60,62could be utilized for performing leveling in other bonding assemblies, such as a thermal bonding assembly or pressure bonding assembly.

In the embodiment illustrated inFIGS. 5 and 6, one or more external sensors60,62are provided on either the horn or anvil in order to measure one or more operational parameters associated with operation of the ultrasonic assembly. The external sensors60,62may be any of a number of types of known sensors, including load cells, optical sensors, EMF sensors, strain gauges, temperature sensors, or sonar sensors, for example. For purposes of explanation, the embodiment discussed here below is described with two sensors60,62being in the form of load cells (hereinafter “load cells60,62”) that acquire a force measurement. Additionally, while the load cells60,62are illustrated as being incorporated into horn26, it is recognized that the load cells60,62could alternatively be incorporated into anvil14. Yet other embodiments may include a single external sensor or three or more sensors.

According to an exemplary embodiment, a pair of load cells60,62is provided on horn26—with a first load cell60in close proximity to a first lateral side of the horn26and the second load cell62in close proximity to a second lateral side of the horn26—such that the load cells60,62are generally on opposing sides of the horn26. With the load cells60,62positioned in such a manner, the load cells60,62operate to measure a force value at each of the opposing sides of the horn26—hereinafter referred to as F1and F2.

In operation, the load cells60,62measure force values F1and F2indicative of the interaction of the ultrasonic horn26with the anvil14in order to provide for a determination of the leveling condition of the horn26with respect to the anvil14. The measured force values F1and F2are provided to the PLC28, where comparison of the force values F1and F2is performed in order to determine the leveling condition.

The method for leveling the ultrasonic horn26relative to the anvil14using measured force values begins with the load cells60,62measuring force values F1, F2with the horn26at a first position or orientation and providing these measurements to the PLC28. Subsequent to the measurements, the PLC28then compares the force values F1, F2to determine if the values are equal or within a predetermined standard deviation of one another. If the force values F1, F2are equal (or within a predetermined standard deviation of one another), the PLC28determines that the horn26and anvil14are in a level or parallel arrangement, and thus no adjustment of the horn26is required. Conversely, if the force values F1, F2are not equal (or within a predetermined standard deviation of one another), the PLC28determines that the horn26and anvil14are in a non-level arrangement and thus operates the actuator32to reorient the horn26relative to the anvil14—with the actuator32causing the horn26to rotate in a first direction, from a first position to a second position.

Upon the horn26rotating to the second position, the load cells60,62again measure force values F1, F2and provide these measurements to the PLC28. The PLC28then compares these force values F1, F2to determine if the values are equal or within a predetermined standard deviation of one another. If the force values F1, F2are still not equal (or within a predetermined standard deviation of one another), the PLC28determines that the horn26and anvil14are in a non-level arrangement and operates the actuator32to reorient the horn26relative to the anvil14—with the actuator32causing the horn26to continue to rotate in the first direction, from the second position to a third position. The PLC28continues to operate actuator32in this manner until it is determined that the values F1, F2are equal or within a predetermined standard deviation of one another—with the horn26and anvil14in a level or parallel arrangement

Referring toFIG. 7, a graphic analysis of the force value readings F1, F2over time is shown for purposes of illustration. During the time span64, the force values F1and F2are the same or within a predetermined suitable standard deviation. Force readings having an equal value or that are within a predetermined suitable standard deviation indicates that the ultrasonic horn26is level with respect to the anvil14. At a transition point66, the force value for F1drops—indicating a distance D1separation between the ultrasonic horn26and the anvil14. The drop in the force value F1is indicated by the graphic illustration section drop68. Additionally, at a transition point66, the force value for F2rises—indicating a distance D2separation between the ultrasonic horn26and the anvil14. The rise in the force value F2is indicated by the graphic illustration section rise70. The graphical readings of F1and F2, as indicated at68and70, indicate the ultrasonic horn26is not level with respect to the anvil14, as the force values F1, F2are not equal and not within a predetermined suitable standard deviation. Referring toFIG. 8, a graphic analysis of the force value readings F1, F2over time illustrates that the ultrasonic horn26is level with respect to the anvil14. During the time span72, the force values F1and F2are thus the same or within a predetermined standard deviation.

Referring now toFIG. 9, and with continued reference toFIGS. 1-6, a method74for leveling an ultrasonic horn26and anvil14in an ultrasonic assembly10via a closed-loop control system16is shown, according to an embodiment of the invention.

The method74begins at STEP75with the monitoring of one or more operational parameters of the ultrasonic assembly10. According to embodiments of the invention, the measurements may be acquired via direct monitoring, measurement, or calculation by the generator30, by an induction sensor50positioned on (or spliced into) the high frequency cable36connecting the generator30and ultrasonic horn assembly12, or by external sensor(s)60,62integrated with the horn26or anvil14. The operational parameters monitored by the generator30may comprise one of power, frequency, amplitude, or charge/capacitance, as non-limiting examples. The operational parameter measured by the induction sensor50may comprise current. The operational parameters measured by the external sensors60,62may comprise force, distance (between the horn and anvil), or temperature, as non-limiting examples.

At STEP76, the PLC28causes the actuator32to iteratively rotate the horn26(or anvil14in an alternative embodiment) in a first direction. The operational parameter is measured again at STEP77.

At STEP78, a determination is made as to whether the horn26and anvil14are in an optimized parallel or level arrangement based on the monitored operational parameters acquired at STEP75and STEP77. The PLC28receives the operational parameters and performs an analysis thereof via a comparison of the operational parameters in order to determine the leveling condition.

In an embodiment where the acquired operational parameter comprises power readings, acquired either via generator30directly or via induction sensor50, STEP78includes the PLC28functioning to operate the actuator32to iteratively reorient the ultrasonic horn26relative to the anvil14until an optimized horn and anvil orientation is identified. The identification of the optimized orientation is obtained via the PLC28causing the actuator32to iteratively rotate the horn26in a first direction and acquiring updated power readings after each rotation. The PLC28compares power readings after each rotation and, when a subsequent power value reading is greater than the immediately preceding power reading, the PLC28will determine that facing surfaces27,29of the horn26and anvil14are not in an optimized orientation or parallel/level relative to one another (as indicated at80). The PLC28will then cause the actuator32to continue to rotate the horn26in the first direction at STEP76—with the method then looping back to STEP77for further monitoring of power values.

In the event that a subsequent power reading that is less than the immediately preceding power reading, the PLC28may take one of two actions. In one embodiment, the PLC28identifies the current horn/anvil orientation as corresponding to an optimized orientation (as indicated at82). Thereafter, the current horn/anvil orientation is flagged as an optimized level condition or parallel orientation at STEP86. Alternatively, upon determining that a subsequent power reading that is less than the immediately preceding power reading, method74may proceed to optional STEP84wherein the PLC28controls the actuator32to rotate the horn26in a second direction (opposite the first direction) to return to the previous position. The resulting horn or anvil position is flagged as an optimized level condition or parallel orientation at STEP86. Thereafter, the method loops back to STEP77for further monitoring of power values.

In an embodiment where the acquired operational parameter is an operational parameter (e.g., force or distance readings) acquired via external sensors60,62, method74includes the PLC28functioning to operate the actuator32to iteratively reorient the ultrasonic horn26relative to the anvil14until sensor readings from generally opposing sides of the horn26(or anvil14) are equal or within a predetermined standard deviation. If the force/distance values from opposing sides of the horn26or anvil14are equal or within a predetermined standard deviation of one another, the PLC28determines that the horn26and anvil14are in an optimized level or parallel arrangement (as indicated at82) and flags the orientation as optimized at STEP86. The PLC28thus does not send command signals to the actuator32, and the method loops back to STEP77for further monitoring of power values. Conversely, if the force/distance values from opposing sides of the horn26or anvil14are not equal or within a predetermined standard deviation of one another, the PLC28determines that the horn26and anvil14are in a non-level arrangement (as indicated at80) and thus causes the actuator32to reorient the ultrasonic horn26relative to the anvil14at STEP76and continue to monitor force/distance values at STEP77.

While embodiments of the invention described above are directed to an ultrasonic assembly10and closed-loop system16for leveling of the horn26and anvil14, it is recognized that the closed-loop control system16described above may also be utilized to monitor and adjust a gap between the horn26and anvil14, according to another embodiment. That is, a closed-loop control system16may be employed for performing both gap control and leveling in the ultrasonic assembly10.

Referring now toFIG. 10, the ultrasonic assembly10is illustrated where closed-loop control system16operates to perform a gap adjustment between the horn26and the anvil14. In performing such a gap adjustment, the generator30acquires a plurality of operational parameter measurements that are indicative of the operation of the ultrasonic assembly10and of a gap or distance86of the horn26from the anvil14. The generator30provides those measurements to the PLC28for comparison thereof and determination of the gap/distance86. The operational parameter measurements may comprise power, capacitance, frequency, or amplitude as non-limiting examples. In one exemplary embodiment, the PLC28compares a plurality of power readings in order to maintain a predetermined target power value that corresponds to a desired gap between the horn26and the anvil14.

As with performing leveling in the ultrasonic assembly10, the generator30may measure power values indicative of the interaction of the horn26with the anvil14(or capacitance, frequency, or amplitude) or, alternatively, induction sensor50may measure current/power values indicative of the interaction of the horn26with the anvil14, in order to provide for a determination of an ideal gap distance between the horn26and the anvil14. The measured power/current values are provided to the PLC28, where comparison of the power/current values is performed in order to determine the ideal gap distance. The position of the horn26, i.e., distance thereof from the anvil14, is incrementally adjusted via operation of actuator32responsive to a plurality of comparisons of the power/current readings by the PLC28(such as from a distance D1, to a distance D2, to a distance D3) until the PLC28achieves a predetermined target value that corresponds to an ideal gap distance between the horn26and the anvil14. That is, actuator32moves ultrasonic horn assembly12(i.e., horn26) in a direction88until a gap/distance86is set that corresponds with the target power/current value.

It is recognized that embodiments of the present invention, including the method74shown and described inFIG. 9, may be implemented is various types of ultrasonic assemblies. In one embodiment, and as shown inFIG. 11, an ultrasonic assembly may be provided in which a single generator30may be used to gather power data from multiple ultrasonic horns26(associated with one or more anvils14) and pass such data to a PLC28to determine a leveling condition of the horns. In such an embodiment, a switching device90is coupled between the generator30and the ultrasonic horns26that is operable to selectively transmit power (for example) from each of the respective ultrasonic horns26to the generator30, to enable power measurement for each of the horns26.

Beneficially, embodiments of the invention thus provide a closed-loop, automated apparatus and method for adjusting the gap, or distance, between the ultrasonic horn and the patterned anvil and/or for leveling or paralleling the ultrasonic horn and the patterned anvil relative to one another. The automated gap control and leveling system reduces the dependency on manual gap control and/or leveling of the ultrasonic horn and anvil. The automated gap control and leveling system also provides for gap control and/or leveling adjustments to be made while the ultrasonic assembly continues to run. The automated gap control and leveling system further provides for continued measurement of the gap distance and leveling condition between the ultrasonic horn and patterned anvil and adjusts the gap and/or leveling based upon the measurement results. Still further, the automated gap control and leveling system provides for gap control and/or leveling adjustments to be made due to a change in the operating speed of the manufacturing machine on which it operates, due to thermal growth of the ultrasonic horn, and/or due to material thickness of the web material or object subject to the ultrasonic frequency.

Therefore, according to one embodiment of the invention, an apparatus for forming bonds on a web includes an anvil, a bonding device positioned adjacent the anvil and configured to interact with the anvil to form the bonds on the web, and an actuator that enables adjustment of an orientation between the bonding device and the anvil. The apparatus also includes a closed-loop control system configured to control operation of the actuator, the closed-loop control system configured to monitor an operational parameter of the apparatus indicative of interaction of the bonding device with the anvil, determine whether the bonding device is parallel or substantially parallel with the anvil based on the operational parameter, and when the bonding device is not parallel or substantially parallel with the anvil, cause the actuator to adjust the orientation between the bonding device and the anvil.

According to another embodiment of the invention, a method for leveling a bonding device and anvil in an assembly via a closed-loop control system is provided. The method includes monitoring an operational parameter of the assembly indicative of interaction of the bonding device with the anvil and determining, based on the operational parameter, whether the bonding device and the anvil are parallel or substantially parallel. The method also includes controlling an actuator to adjust an orientation between the bonding device and the anvil when the bonding device and the anvil are determined to not be parallel or substantially parallel. The monitoring of the operational parameter and the operation of the actuator to adjust the orientation between the bonding device and the anvil is performed via a closed-loop control scheme.

According to yet another embodiment of the invention, an apparatus for forming bonds on a web includes an anvil, a bonding device positioned adjacent the anvil and configured to interact with the anvil to form the bonds on the web, and an actuator that enables adjustment of a spacing between the bonding device and the anvil. The apparatus also includes a closed-loop control system configured to control operation of the actuator. The closed-loop control system is configured to monitor an operational parameter indicative of interaction of the bonding device with the anvil, compare the operational parameter to a predetermined target value, and when the operational parameter does not match the predetermined target value, cause the actuator to move one of the bonding device and the anvil to adjust the spacing between the bonding device and the anvil. The closed-loop control system is configured to compare a plurality of operational parameters to the predetermined target value and cause the actuator to incrementally adjust a position of one of the bonding device and the anvil to adjust the spacing between the bonding device and the anvil. The position of one of the bonding device and the anvil is adjusted until the monitored operational parameter matches the predetermined target value. In one embodiment the bonding device is an ultrasonic horn. In one embodiment the operational parameter comprises a power value.