Abstract: An illustrative example embodiment of a structure for supporting a heating, ventilation and air conditioning (HVAC) unit includes a frame having support members configured to be situated beneath the HVAC unit to support a weight of the HVAC unit, which is directed in a vertical direction. The frame is at least partially situated in a plane that is perpendicular to the vertical direction. A supply air passage and a return air passage are supported by the frame. The return air passage has a first side and a second side opposite the first side. The first side is oriented at a first oblique angle relative to the plane. The second side is oriented at a second oblique angle relative to the plane. The first oblique angle is different than the second oblique angle.

Abstract: A system and method for modifying a work piece surface of high melting temperature materials such as Advanced High Strength Steels, wherein a friction stir welding tool may include cutting elements located on the outside diameter of a collar assembly, wherein the collar assembly may be retrofitted for existing friction stir welding tools, or may be designed as a custom attachment for a new hybrid friction stir welding tool, wherein the surface of the work piece may be modified by removing detrimental flash and burr created during operation of the friction stir welding tool.

Abstract: A system and method for friction stir welding of small diameter tubing, wherein the small diameter tubing is held in a correct position with a grasp sufficient to perform FSW when the tubing is comprised of high melting temperature materials, wherein the small diameter tubing can be rotated by the positioning and holding system while a FSW tool is held stationary, or vice versa, wherein internal mandrels are also described which can fit inside the smaller dimensions of the small diameter tubing and expand to provide a counter force to prevent deformation of the tubing when forces are applied by the FSW tool, wherein new FSW tool geometries are also described which enable the FSW tool to direct more heat on a tool/workpiece interface to counteract a lack of contact between the FSW shoulder and the workpiece because of tube curvature, and wherein the FSW tool is positioned on a small diameter tube by trailing the joint to provide desirable heating at the joint/workpiece interface and surface finishing.

Abstract: A system and method for modifying a work piece surface of high melting temperature materials such as Advanced High Strength Steels, wherein a friction stir welding tool may include cutting elements located on the outside diameter of a collar assembly, wherein the collar assembly may be retrofitted for existing friction stir welding tools, or may be designed as a custom attachment for a new hybrid friction stir welding tool, wherein the surface of the work piece may be modified by removing detrimental flash and burr created during operation of the friction stir welding tool.

Abstract: A system and method for modifying a work piece surface of high melting temperature materials such as Advanced High Strength Steels, wherein a friction stir welding tool may include cutting elements located on the outside diameter of a collar assembly, wherein the collar assembly may be retrofitted for existing friction stir welding tools, or may be designed as a custom attachment for a new hybrid friction stir welding tool, wherein the surface of the work piece may be modified by removing detrimental flash and burr created during operation of the friction stir welding tool.

Abstract: A system and method for friction stir welding of small diameter tubing, wherein the small diameter tubing is held in a correct position with a grasp sufficient to perform FSW when the tubing is comprised of high melting temperature materials, wherein the small diameter tubing can be rotated by the positioning and holding system while a FSW tool is held stationary, or vice versa, wherein internal mandrels are also described which can fit inside the smaller dimensions of the small diameter tubing and expand to provide a counter force to prevent deformation of the tubing when forces are applied by the FSW tool, wherein new FSW tool geometries are also described which enable the FSW tool to direct more heat on a tool/workpiece interface to counteract a lack of contact between the FSW shoulder and the workpiece because of tube curvature, and wherein the FSW tool is positioned on a small diameter tube by trailing the joint to provide desirable heating at the joint/workpiece interface and surface finishing.

Abstract: A mandrel that provides a counter-force to the pressure exerted on the outside of a pipe or other arcuate surface by a friction stir welding tool, wherein the mandrel is expandable through the use of a wedge, and wherein the mandrel enables multiple friction stir welding heads to simultaneously perform welding on the arcuate surface.

Abstract: A control parameter ramp profile that enables control parameters to be modified in a non-linear manner, such that as a temperature set point of a tool or a weld is approached, the control parameter ramp profile enables the temperature set point to be approached in a manner that prevents temperature overshoot and therefore creating a better weld along the length thereof, wherein the control parameter ramp profile includes but is not limited to proportional, exponential or an S-curve waveform.

Abstract: A control parameter ramp profile that enables control parameters to be modified in a non-linear manner, such that as a temperature set point of a tool or a weld is approached, the control parameter ramp profile enables the temperature set point to be approached in a manner that prevents temperature overshoot and therefore creating a better weld along the length thereof, wherein the control parameter ramp profile includes but is not limited to proportional, exponential or an S-curve waveform.

Abstract: A mandrel that provides a counter-force to the pressure exerted on the outside of a pipe or other arcuate surface by a friction stir welding tool, wherein the mandrel is expandable through the use of a wedge, and wherein the mandrel enables multiple friction stir welding heads to simultaneously perform welding on the arcuate surface.

Abstract: A friction stir tool is provided to perform friction stir riveting using a partially consumable pin, wherein the pin includes a cutting edge on a bottom surface thereof, wherein the tool is rotated at a first speed to enable cutting by the pin into a first material that is overlapping a second material, wherein after the pin has cut to a sufficient depth, the rotational speed of the tool is increased to thereby enable plasticization of the consumable pin, the first material, and the second material, wherein the tool is then rapidly decelerated until stopped, enabling diffusion bonding between the pin, the first material and the second material.

Abstract: A mandrel that provides a counter-force to the pressure exerted on the outside of a pipe or other arcuate surface by a friction stir welding tool, wherein the mandrel is expandable through the use of a wedge, and wherein the mandrel enables multiple friction stir welding heads to simultaneously perform welding on the arcuate surface.

Abstract: A new control variable is introduced, that when combined with previous dependent control criteria on other variables results in a control program that can create a superior weld while minimizing wear on the FSW tool, wherein the tool repeatedly experiences the same thermal and mechanical loading within specified control windows during every repeated weld sequence because flow stresses and tool loads are driven by temperature, and dependent control loops account for differences in material and heat that is transferred at different rates in varying locations throughout a friction stir weld.

Abstract: A system and method for friction stir welding of small diameter tubing, wherein the small diameter tubing is held in a correct position with a grasp sufficient to perform FSW when the tubing is comprised of high melting temperature materials, wherein the small diameter tubing can be rotated by the positioning and holding system while a FSW tool is held stationary, or vice versa, wherein internal mandrels are also described which can fit inside the smaller dimensions of the small diameter tubing and expand to provide a counter force to prevent deformation of the tubing when forces are applied by the FSW tool, wherein new FSW tool geometries are also described which enable the FSW tool to direct more heat on a tool/workpiece interface to counteract a lack of contact between the FSW shoulder and the workpiece because of tube curvature, and wherein the FSW tool is positioned on a small diameter tube by trailing the joint to provide desirable heating at the joint/workpiece interface and surface finishing.

Abstract: A friction stir tool is provided to perform friction stir riveting using a partially consumable pin, wherein the pin includes a cutting edge on a bottom surface thereof, wherein the tool is rotated at a first speed to enable cutting by the pin into a first material that is overlapping a second material, wherein after the pin has cut to a sufficient depth, the rotational speed of the tool is increased to thereby enable plasticization of the consumable pin, the first material, and the second material, wherein the tool is then rapidly decelerated until stopped, enabling diffusion bonding between the pin, the first material and the second material.

Abstract: A new control variable is introduced, that when combined with previous dependent control criteria on other variables results in a control program that can create a superior weld while minimizing wear on the FSW tool, wherein the tool repeatedly experiences the same thermal and mechanical loading within specified control windows during every repeated weld sequence because flow stresses and tool loads are driven by temperature, and dependent control loops account for differences in material and heat that is transferred at different rates in varying locations throughout a friction stir weld.

Abstract: A friction stir tool is provided to perform friction stir riveting using a partially consumable pin, wherein the pin includes a cutting edge on a bottom surface thereof, wherein the tool is rotated at a first speed to enable cutting by the pin into a first material that is overlapping a second material, wherein after the pin has cut to a sufficient depth, the rotational speed of the tool is increased to thereby enable plasticization of the consumable pin, the first material, and the second material, wherein the tool is then rapidly decelerated until stopped, enabling diffusion bonding between the pin, the first material and the second material.

Abstract: A mandrel that provides a counter-force to the pressure exerted on the outside of a pipe or other arcuate surface by a friction stir welding tool, wherein the mandrel is expandable through the use of a wedge, and wherein the mandrel enables multiple friction stir welding heads to simultaneously perform welding on the arcuate surface.

Abstract: A new control variable is introduced, that when combined with previous dependent control criteria on other variables results in a control program that can create a superior weld while minimizing wear on the FSW tool, wherein the tool repeatedly experiences the same thermal and mechanical loading within specified control windows during every repeated weld sequence because flow stresses and tool loads are driven by temperature, and dependent control loops account for differences in material and heat that is transferred at different rates in varying locations throughout a friction stir weld.

Abstract: A mandrel that provides a counter-force to the pressure exerted on the outside of a pipe or other arcuate surface by a friction stir welding tool, wherein the mandrel is expandable through the use of a wedge, and wherein the mandrel enables multiple friction stir welding heads to simultaneously perform welding on the arcuate surface.