Closed loop composite welding and bonding system using radio-frequency and pressure
A bonding system includes a heating element, an actuator, an infrared camera, a pressure sensor and/or a displacement sensor, one or more processors, and a computer readable medium storing instructions that, when executed by the one or more processors, cause the bonding system to perform functions including providing a first control signal to a heating element, thereby heating a workpiece with electromagnetic radiation having one or more oscillation frequencies within a range of 1 MHz to 2.00 MHz. and providing a second control signal to an actuator, thereby applying a pressure to the workpiece via the actuator. The functions also include detecting a temperature of the workpiece, the pressure applied to the workpiece, and/or a displacement of the actuator, and adjusting the first control signal and/or the second control signal based on the temperature of the workpiece, the pressure applied to the workpiece, or the displacement of the actuator.
1 . A method comprising:
providing a first control signal to a heating element, thereby heating a workpiece with electromagnetic radiation having one or more oscillation frequencies within a range of 1 MHz to 200 MHz;
providing a second control signal to an actuator, thereby applying a pressure to the workpiece via the actuator;
detecting, via an infrared camera, a temperature of the workpiece;
detecting, via a pressure sensor, the pressure applied to the workpiece;
adjusting the first control signal based on the temperature of the workpiece or the pressure applied to the workpiece;
adjusting the second control signal based on the temperature of the workpiece or the pressure applied to the workpiece;
making a determination that a threshold duration has passed while the temperature of the workpiece and the pressure applied to the workpiece satisfy process parameters; and
disabling the first control signal and the second control signal in response to making the determination.
2 . The method of claim 1 , wherein adjusting the first control signal comprises adjusting the first control signal, thereby reducing a temperature difference between the temperature of the workpiece and a target temperature.
3 . The method of claim 1 , wherein adjusting the second control signal comprises adjusting the second control signal, thereby reducing a pressure difference between the pressure applied to the workpiece and a target pressure.
4 . The method of claim 3 , wherein providing the first control signal comprises providing the first control signal in response to determining that the pressure difference is less than a threshold pressure difference.
5 . The method of claim 1 , wherein adjusting the second control signal comprises adjusting the second control signal, thereby reducing a displacement difference between a displacement of the actuator and a target displacement.
6 . The method of claim 5 , wherein adjusting the second control signal comprises adjusting the second control signal based on determining that the temperature of the workpiece is within a range of 40° C. to 360° C.
7 . The method of claim 6 , wherein adjusting the second control signal comprises adjusting the second control signal based on determining that the temperature of the workpiece has been within the range of 40° C. to 360° C. for at least a threshold duration.
8 . The method of claim 1 , wherein the heating element takes a form of a radio frequency antenna.
9 . The method of claim 1 , wherein the workpiece comprises a non-conductive matrix material having electrically conductive particles dispersed therein.
10 . The method of claim 9 , wherein the non-conductive matrix material comprises a ceramic, a polymer, a thermoplastic, or a thermoset.
11 . The method of claim 9 , wherein the electrically conductive particles comprise carbon nanotubes, graphene, graphite, graphene oxide, laser induced graphene, carbon black, carbon fibers, char, or MXene.
12 . The method of claim 1 , wherein the workpiece comprises a first layer having a first dielectric constant less than 3, a second layer having a second dielectric constant less than 3, and a third layer comprising electrically conductive particles between the first layer and the second layer.
13 . The method of claim 12 , wherein heating the workpiece comprises heating the electrically conductive particles, thereby transferring heat via conduction to the first layer and to the second layer and creating a mechanical bond between the first layer and the second layer.
14 . The method of claim 12 , further comprising applying the third layer onto the first layer and/or onto the second layer prior to heating the electrically conductive particles.
15 . The method of claim 1 , wherein providing the first control signal comprises providing the first control signal between a first terminal of the heating element and a second terminal of the heating element, thereby generating an electromagnetic field within and adjacent to a gap between the first terminal and the second terminal.
16 . The method of claim 1 , wherein heating the workpiece comprises heating the workpiece with the electromagnetic radiation from a first side of the workpiece, and
wherein applying the pressure to the workpiece comprises applying the pressure to the workpiece via the actuator from a second side of the workpiece opposite the first side.
17 . A non-transitory computer readable medium storing instructions that, when executed by a bonding system, cause the bonding system to perform the method of claim 1 .
18 . A bonding system comprising:
a signal generator and/or a radio frequency (RF) power amplifier;
the heating element of claim 1 ;
the actuator of claim 1 ;
the infrared camera of claim 1 ;
the pressure sensor of claim 1 ;
one or more processors; and
a non-transitory computer readable medium storing instructions that, when executed by the one or more processors, cause the bonding system to perform the method of claim 1 .
19 . The bonding system of claim 18 , wherein adjusting the first control signal comprises adjusting the first control signal, thereby reducing a temperature difference between the temperature of the workpiece and a target temperature.