SYSTEM AND METHOD FOR VACUUM ACTUATED THERMOPLASTIC COMPOSITE WELDING
A system using a pressure differential to clamp welding heads on opposite sides of a joint of a thermoplastic composite structure to be welded. The heads are positioned over the joint opposite each other. Each head includes a housing defining a chamber having a lower pressure such that the pressure differential forces the head against the side. Each head includes a contour plate located in the space and against the joint, and at least one of the heads includes a heater located in the space and heating the contour plate to a welding temperature. The system may also include a first arm coupled with one of the heads and moving it along the joint so as to remain aligned with the other head, and a second arm coupled with the other head and moving it along the joint while the system welds the joint in successive overlapping sections.
1 . A system for welding a joint of a structure, the system comprising:
a first welding head positioned over the joint on a first side of the structure, the first welding head comprising:
a first housing defining a first chamber between the first housing and the first side, the first chamber comprising a first lower pressure than atmospheric pressure such that a first pressure differential forces the first welding head against the first side,
a first contour plate located in the first chamber and compressing the joint on the first side, wherein the first contour plate is smaller by a first factor than the first housing so that the first pressure differential caused by the first lower pressure forces the first contour plate against the joint with a first force that is greater than atmospheric pressure; and
a second welding head positioned over the joint opposite the first welding head on a second side of the structure, the second welding head comprising:
a second housing defining a second chamber between the second housing and the second side, the second chamber comprising second lower pressure than atmospheric pressure such that a second pressure differential forces the second welding head against the second side,
a second contour plate located in the second chamber compressing the joint on the second side, wherein the second contour plate is smaller by a second factor than the second housing so that the second pressure differential caused by the second lower pressure forces the second contour plate against the joint with a second force that is greater than atmospheric pressure, and
a heater located in the second chamber and heating the second contour plate to a welding temperature to weld the joint.
2 . The system of claim 1 , wherein the structure is a thermoplastic composite structure.
3 . The system of claim 1 , wherein the first lower pressure is no more than five percent different from the second lower pressure.
4 . The system of claim 1 , wherein the first contour plate has a different area than the second contact plate.
5 . (canceled)
6 . The system of claim 1 , wherein the heater located in the second chamber and heating the second contour plate is a second heater, and the system further comprising a first heater located in the first chamber and heating the first contour plate to the welding temperature.
7 . The system of claim 1 , further comprising:
a first splice piece located in the first chamber and positioned between the joint and the first contour plate so as to be welded over the joint; and
a second splice piece located in the second chamber and positioned between the joint and the second contour plate so as to be welded over the joint.
8 . The system of claim 1 , further comprising an aligner aligning the first and second housings on opposite sides of the structure.
9 . The system of claim 1 , further comprising:
a first compressible seal maintaining the first lower pressure in the first chamber; and
a second compressible seal maintaining the second lower pressure in the second chamber.
10 . The system of claim 1 , further comprising:
a first landing pad extending between the first housing and the first side of the structure and reducing deformation of the structure; and
a second landing pad extending between the second housing and the second side of the structure and reducing deformation of the structure.
11 . The system of claim 10 , further comprising an actuator moveable between a first position in which the actuator exerts a force on an end of the first landing pad, and a second position in which in which the actuator does not exert the force on the end of the first landing pad.
12 . The system of claim 1 , further comprising:
a first vacuum connection located on the first housing and connected to a vacuum source to create the first lower pressure in the first chamber; and
a second vacuum connection located on the second housing and connected to the vacuum source to create the second lower pressure in the second chamber.
13 . The system of claim 1 , further comprising:
a first heat sink located in the first chamber and in physical contact with the first side to remove heat from the first side; and
a second heat sink located in the second chamber in physical contact with the second side to remove heat from the second side.
14 . The system of claim 1 , further comprising:
a first insulation spacer located in the first chamber and controlling a transfer of heat from the first heater; and
a second insulation spacer located in the second chamber and controlling a transfer of heat from the second heater.
15 . The system of claim 1 , further comprising:
a first transfer bar located in the first chamber and extending with a first adjustable length between the first housing and the first contour plate and transferring a force of the first pressure differential to the first contour plate; and
a second transfer bar located in the second chamber and extending with a second adjustable length between the second housing and the second contour plate and transferring a force of the second pressure differential to the second contour plate.
16 . The system of claim 1 , further comprising:
a first vacuum regulator coupled with the first chamber and independently controlling the first lower pressure; and
a second vacuum regulator coupled with the second chamber and independently controlling the second lower pressure.
17 . The system of claim 1 , further comprising:
a first actuator extending between the first housing and the first contour plate and selectively advancing and withdrawing the first contour plate relative to the first side of the structure; and
a second actuator extending between the second housing and the second contour plate and selectively advancing and withdrawing the second contour plate relative to the second side of the structure.
18 . The system of claim 1 , further comprising:
a first arm coupled with the first welding head and moving the first welding head along the joint so as to remain aligned with the second welding head; and
a second arm coupled with the second welding head and moving the second welding head along the joint, wherein the system welds the joint in successive overlapping sections.
19 . A system for welding a joint of a thermoplastic composite structure, the system comprising:
a first welding head positioned over the joint on a first side of the thermoplastic composite structure, the first welding head comprising:
a first housing defining a first chamber between the first housing and the first side, the first chamber comprising a first lower pressure than atmospheric pressure such that a first pressure differential forces the first welding head against the first side with a first force,
a first contour plate located in the first chamber and compressing the joint on the first side,
a first transfer bar located in the first chamber and extending with a first adjustable length between the first housing and the first contour plate and transferring the first force of the first pressure differential to the first contour plate, and
a first heater located in the first chamber and heating the first contour plate to a welding temperature;
a second welding head positioned over the joint opposite the first welding head on a second side of the thermoplastic composite structure, the second welding head comprising:
a second housing defining a second chamber between the second housing and the second side, the second chamber comprising second lower pressure than atmospheric pressure such that a second pressure differential forces the second welding head against the second side with a second force,
a second contour plate located in the second chamber compressing the joint on the second side,
a second transfer bar located in the second chamber and extending with a second adjustable length between the second housing and the second contour plate and transferring the second force of the second pressure differential to the second contour plate, and
a second heater located in the second chamber and heating the second contour plate to the welding temperature to weld the joint.
20 . A system for welding a joint of a thermoplastic composite structure, the system comprising:
a first welding head positioned over the joint on a first side of the thermoplastic composite structure, the first welding head comprising:
a first housing defining a first chamber between the first housing and the first side, the first chamber comprising a first lower pressure than atmospheric pressure such that a first pressure differential forces the first welding head against the first side,
a first vacuum connection located on the first housing and connected to a vacuum source to create the first lower pressure in the first chamber,
a first contour plate located in the first chamber and compressing the joint on the first side, wherein the first contour plate is smaller by a first factor than the first housing so that the first pressure differential forces the first contour plate against the joint with a first force that is greater than atmospheric pressure,
a first transfer bar located in the first chamber and extending with a first adjustable length between the first housing and the first contour plate and transferring the first force of the first pressure differential to the first contour plate, and
a first heater located in the first chamber and heating the first contour plate to a welding temperature;
a second welding head positioned over the joint opposite the first welding head on a second side of the thermoplastic composite structure, the second welding head comprising:
a second housing defining a second chamber between the second housing and the second side, the second chamber comprising second lower pressure than atmospheric pressure such that a second pressure differential forces the second welding head against the second side,
a second vacuum connection located on the second housing and connected to the vacuum source to create the second lower pressure in the second chamber,
a second contour plate located in the second chamber compressing the joint on the second side, the second contour plate is smaller by a second factor than the second housing so that the second pressure differential forces the second contour plate against the joint with a second force that is greater than atmospheric pressure,
a second transfer bar located in the second chamber and extending with a second adjustable length between the second housing and the second contour plate and transferring the second force of the second pressure differential to the second contour plate, and
a second heater located in the second chamber and heating the second contour plate to the welding temperature; and
an aligner aligning the first and second housings on the first and second sides of the structure.