Abstract: An apparatus provides automatic lacing of hairpin tubes through the holes of a heat exchanger fin stack. This apparatus includes a plurality of identical extendable guide rods, each positioned in approximate alignment to engage an open end of a respective heat exchanger tube which is positioned adjacent to a respective fin stack hole. The plurality of guide rods are extended in unison through the holes of the heat exchanger fin stack to positions within the open ends of the hairpin tubes. Lead guides are located toward the end of each guide rod. The lead guides have forward and backward tapered surfaces extending from a central portion of maximum diameter. The lead guides ensure that the holes in the individual fins are moved into coaxial alignment with the guide rods as they travel through the fin stack. Once the guide rod ends are within the open ends of the hairpin tubes, self-aligning engagement fingers on each guide rod lead end expand to engage the internal diameter of a respective hairpin tube.

Abstract: An apparatus for the automatic lacing (drawing) of hairpin tubes through the holes of a heat exchanger fin stack is provided. This apparatus includes a plurality of identical extendable guide rods, each positioned in approximate alignment to engage an open end of a respective heat exchanger tube which is positioned adjacent to a respective fin stack hole. The plurality of guide rods are extended in unison through the holes of the heat exchanger fin stack to positions within the open ends of the hairpin tubes. A self aligning knurl structure on each guide rod lead end is expanded to engage the respective I.D. of a respective hairpin tube. The guide rods are then retracted in unison pulling the tubes through the fin stack holes. A self regulating pressure mechanism assures that the pressure exerted by an expanding knurl end is within a predetermined range. Once the tubes have been laced, the knurl structures are collapsed and the guide rods withdraw from the tubes.

Abstract: A method of using an apparatus for the automatic lacing (drawing) of hairpin tubes through the holes of a heat exchanger fin stack includes using a plurality of identical extendable guide rods, each positioned in approximate alignment to engage an open end of a respective heat exchanger tube which is positioned adjacent to a respective fin stack hole. The plurality of guide rods are extended in unison through the holes of the heat exchanger fin stack to positions within the open ends of the hairpin tubes. A self aligning knurl structure on each guide rod lead end is expanded to engage the respective I.D. of a respective hairpin tube. The guide rods are then retracted in unison pulling the tubes through the fin stack holes. A self regulating pressure mechanism assures that the pressure exerted by an expanding knurl end is within a predetermined range. Once the tubes have been laced, the knurl structures are collapsed and the guide rods withdraw from the tubes.