SYSTEM AND METHOD FOR THERMOPLASTIC WELDING USING AN INDUCED THERMAL GRADIENT
A system and method for thermoplastic composite welding comprising a cooling means and a heat source. The cooling means cools a heat-side laminate so as to create a thermal gradient in the heat-side laminate. The heat source heats the heat-side laminate after the cooling step is initiated but before the thermal gradient dissipates so that a first side of the heat-side laminate closer to the heat source does not deform as faying surfaces of the heat-side laminate and another laminate farther away from the heat source are welded together.
1 . A system for thermoplastic composite welding a heat-side laminate having opposing first and second sides and an opposing laminate having opposing first and second sides together, the system comprising:
a cooling means configured to cool the heat-side laminate so as to create a thermal gradient in the heat-side laminate; and
a welding shoe configured to heat the heat-side laminate after the heat-side laminate is cooled but before the thermal gradient dissipates so that the first side of the heat-side laminate does not deform as the second side of the heat-side laminate and the first side of the opposing laminate are welded together.
2 . The system of claim 1 , wherein the cooling means includes a perforated plenum configured to disperse cooled fluid to the first side of the heat-side laminate.
3 . The system of claim 1 , wherein the cooling means includes a heat sink configured to contact the first side of the heat-side laminate.
4 . The system of claim 1 , wherein the welding shoe comprises an induction coil configured to heat the heat-side laminate via a magnetic field.
5 . The system of claim 1 , wherein the welding shoe comprises an elastomeric pressure pad configured to press the heat-side laminate and the opposing laminate together.
6 . The system of claim 5 , wherein the cooling means is the elastomeric pressure pad, wherein the elastomeric pressure pad is configured to function as a heat sink.
7 . A method of thermoplastic composite welding, the method comprising the steps of:
placing a heat-side laminate having opposing first and second sides adjacent to an opposing laminate having first and second sides;
cooling the heat-side laminate so as to create a thermal gradient in the heat-side laminate; and
heating the heat-side laminate after the cooling step is initiated but before the thermal gradient dissipates so that the first side of the heat-side laminate does not deform as the second side of the heat-side laminate and the first side of the opposing laminate are welded together.
8 . The method of claim 7 , wherein the step of cooling the heat-side laminate includes at least one of immersing the first side of the heat-side laminate in a cold fluid, spraying the first side of the heat-side laminate with a cold fluid, positioning a cooled heat sink near the first side of the heat-side laminate, and subjecting the first side of the heat-side laminate to a convective cooling jet.
9 . The method of claim 7 , the method further comprising the step of applying pressure to at least one of the heat-side laminate and the opposing laminate.
10 . The method of claim 9 , wherein the pressure is applied via an elastomeric pressure pad.
11 . The method of claim 9 , wherein the pressure is applied via a pressure application means, the method further comprising the steps of cooling the pressure application means and cooling the heat-side laminate via the cooled pressure application means before heating the heat-side laminate.
12 . The method of claim 11 , wherein the step of cooling the pressure application means is performed before the step of applying pressure.
13 . The method of claim 10 , wherein the step of heating the heat-side laminate is performed via a welding shoe having the elastomeric pressure pad.
14 . The method of claim 10 , wherein the heat sink includes magnetic flux control material, the heating step including induction welding the second side of the heat-side laminate and the first side of the opposing laminate together, wherein the induction welding includes controlling magnetic fields via the magnetic flux control material.
15 . The method of claim 7 , wherein the induction welding includes exposing at least the heat-side laminate to high-frequency alternating magnetic fields to induce eddy current heating near the second side of the heat-side laminate and the first side of the opposing laminate.
16 . The method of claim 7 , wherein the step of cooling the heat-side laminate includes the step of passing cooled fluid through an internal passage in a heat sink adjacent to the heat-side laminate.
17 . A method of thermoplastic composite welding, the method comprising the steps of:
placing a heat-side laminate having opposing first and second sides adjacent to an opposing laminate having opposing first and second sides;
cooling an elastomeric pressure pad;
cooling the heat-side laminate via the cooled elastomeric pressure pad so as to create a thermal gradient in the heat-side laminate; and
heating the heat-side laminate via a welding shoe after the step of cooling the heat-side laminate is initiated but before the thermal gradient dissipates so that the first side of the heat-side laminate does not deform as the second side of the heat-side laminate and the first side of the opposing laminate are welded together.
18 . The method of claim 17 , wherein the welding shoe comprises the elastomeric pressure pad, the step of cooling the heat-side laminate including drawing heat from the heat-side laminate to the elastomeric pressure pad.
19 . The method of claim 17 , wherein the step of cooling the elastomeric pressure pad includes submersing at least a portion of the welding shoe in a cooled fluid.
20 . The method of claim 17 , wherein the welding shoe repeatedly alternates between cooling the heat-side laminate and heating the heat-side laminate.
21 . A method of thermoplastic composite welding, the method comprising the steps of:
placing a heat-side laminate having opposing first and second sides adjacent to an opposing laminate having first and second sides;
cooling the heat-side laminate via a cold fluid so as to create a thermal gradient in the heat-side laminate;
applying pressure to the heat-side laminate via an elastomeric pressure pad; and
heating the heat-side laminate via high-frequency alternating magnetic fields to induce eddy currents near the second side of the heat-side laminate and the first side of the opposing laminate after the cooling step is initiated but before the thermal gradient dissipates so that the first side of the heat-side laminate does not deform as the second side of the heat-side laminate and the first side of the opposing laminate are welded together.