Load cell closed loop control for rotary ultrasonic bonding apparatus

Closed loop control apparatus for managing pressure generated in a nip, the nip being defined between a rotary ultrasonic horn mounted for rotation about a first axis, and an anvil roll mounted for rotation about a second axis, substantially aligned with the first axis, and wherein the anvil roll is mounted to support structure by anvil support apparatus, and the ultrasonic horn is mounted to the support structure by horn support apparatus, said closed loop control apparatus comprising:

• (a) an adjustor mounted in adjusting relationship with respective one of the anvil support apparatus and the horn support apparatus;
• (b) a load cell connected to one of the anvil support apparatus and the horn support apparatus, said load cell quantifying force representative of pressure being generated in the nip;
• and
• (c) a programmable logic controller connected to said load cell and to said adjustor, for communication with said load cell and said adjustor.

A method of creating ultrasonic bonds in sequentially advancing workpiece segments, the method comprising:

• (a) passing the workpiece segments through a nip defined by a support structure comprising anvil support apparatus supporting an anvil roll mounted for rotation about a first axis, horn support apparatus being connected to and supporting a rotary ultrasonic horn mounted for rotation about a second axis, substantially aligned with the first axis, the anvil support apparatus comprising an anvil moving assembly for moving the anvil roll into contact with the ultrasonic horn, and for moving the anvil roll out of contact with the ultrasonic horn, closed loop control apparatus being connected to one of the anvil support apparatus and the horn support apparatus, the closed loop control apparatus comprising a programmable logic controller, a load cell, and an adjustor;
• (b) activating ultrasonic energy in the ultrasonic horn;
• and
• (c) rotating the ultrasonic horn and the anvil roll in common with movement of the workpiece segments through the nip, thereby applying pressure to the workpiece segments at the nip, and correspondingly creating ultrasonic bonds in the workpiece segments passing through the nip,
• the programmable logic controller being connected to the load cell and the adjustor, and communicating with the load cell and the adjustor, and regulating pressure in the nip by ongoing real-time adjustments to the distance between the anvil support apparatus and the horn support apparatus.

A method of managing pressure generated in a nip, the nip being defined between a rotary ultrasonic horn mounted on horn support apparatus, and an anvil roll mounted on anvil support apparatus, the anvil support apparatus being mounted to a support structure, and defining an adjustable anvil moving assembly, the horn being mounted in general alignment with the anvil roll to define the nip therebetween such that outer working surfaces of the ultrasonic horn and the anvil roll are generally defined in a common surface at the nip, the method comprising:

• (a) employing a load cell connected to one of the horn support apparatus and the anvil support apparatus, and thereby receiving and quantifying force representative of force expressed between the ultrasonic horn and the anvil roll at the nip;
• (b) converting the force applied at the load cell into a communications signal output;
• (c) transmitting the communications signal output to a programmable logic controller programmed to activate an adjustor;
• and
• (d) employing the adjustor to raise or lower the respective anvil support apparatus or horn support apparatus so as to adjust the force being expressed between the anvil roll and the horn at the nip to a desired bond-creating pressure.