Abstract: An improved heat transfer fin structure of the type normally fabricated from sheet metal and wrapped about a conduit to provide enhanced heat transfer efficiency between the conduit and a fluid in contact with the conduit, has a plurality of elongated leg portions spaced apart from each other and openings defined in the space between the leg portions. The structure provides the advantage of high efficiency combined with high peripheral stability.

Abstract: An improved solar energy collector has a twisted expanded metal/bristle fin combination structure which provides improved energy absorbing efficiency, good peripheral stability, and efficient heat transfer capabilities. The structure is normally formed by wrapping and thereby expanding, a lanced sheet metal about a conduit in a spiral fashion. In the preferred embodiment, the outer peripheral structure presents a series of protrusions wherein every other protrusion is twisted at an angle with respect to the spiraling structure.

Abstract: The invention is concerned with a system for monitoring the feed rate of a cut strip which is to be applied to a rotating tube for use in the production of fin tubing and includes a dancing roll to monitor the feed rate of the strip in response to the tension applied by the strip to the dancing roll as it is fed from a direct hydraulic drive during application to the rotating tube, the tension in the strip being maintained essentially constant throughout.

Abstract: The cutting mechanism comprises a driving shaft and a driven shaft. A motor is connected to the driving shaft and rotates the driving shaft in a first direction. A gearing arrangement interconnects the driving and the driven shafts so that rotation of the driving shaft causes concomitant rotation of the driven shaft in a direction opposite to the first direction. Coacting cutting means are provided on the driving and the driven shafts for cutting material received therebetween. A motor is connected to the driven shaft and rotates the driven shaft in a direction opposite to the normal direction of rotation of the driven shaft to eliminate backlash between the coacting gears. Thus, the clearance between the cutting edges of the rotary cutting means is always constant and uniform.

Abstract: A series of thin-walled, heat exchange tubes are soldered to return bends of similar materials so as to complete a flow path through the tube bundle by a process which comprises press-fitting the return bends to the tubes, preheating the return bends and portions of the tube adjacent the bends to a temperature, the average of which is approximately the soldering temperature, soaking the preheated portion in a liquid which will equalize the temperature of the various preheated portions, and ultrasonically soldering the return bends to the tubes.