Abstract: A single-station tube expander apparatus bells and expands the open ends of heat exchanger hairpin tubes in a plate-fin heat exchanger unit. A frame supports belling jaw fingers which close over and the open ends of the tubes so that a belling device can enter the tube ends to urge the tube outward into a profile surface formed in the mating faces of the fingers. Also on the frame are mounted expander jaw fingers which close over tube ends which have been belled previously, and hold the associated hairpin tubes against axial movement while expander rods pass into the associated tube legs to urge the hairpin tube legs outward to contact against the fin plates and tube sheets of the fin pack heat exchanger. The belling fingers and belling device move step by step from one tube to another, and the expander gripping fingers and expander rods follow the belling fingers and belling device.

Abstract: A method for tension expanding a plate fin heat exchanger to provide a heat exchanger with bells of the same form and dimension and then expanding the tube into contact with the tube sheets and hairpin tubes while the bells are clamped to prevent the hairpin tubes from moving.

Abstract: A flexibly programmable belling and tension expanding device for plate fin heat exchanger coils is carried on a shuttle or carriage that moves between first and second work stations. An operator assembles a fin plate heat exchanger unit at a work table at one work station while the device automatically bells and expands the hairpin tubes of another unit at a second station. When assembly is complete, the operator signals a programmable controller, and the shuttle brings the device to the one coil after it completes the expanding of the other, and it commences an automatic expanding operation. Then the operator removes the expanded coil and assembles another coil at the second station while the device is belling and coiling at the one station.

Abstract: An apparatus and process for forming heat-transfer elements wherein platelike fins are secured to the outside wall of a heat-transfer tube. There is provided a bullet-shaped tool which is axially slidably inserted into the heat-transfer tube to effect radial expansion thereof into gripping engagement with the surrounding fins. The tool is freely rotatably supported on the end of a pushing rod, and the peripheral surface of the tool has spiral grooves therein which define small teeth therebetween. By axially pushing the tool into the tube, the teeth bite into the internal wall of the tube and, due to the helical orientation of these teeth, the axial displacement of the tool into the tube causes the tool to simultaneously rotate. This causes not only radial expansion of the tube for gripping the fins, but simultaneously results in the formation of spiral-like grooves on the internal wall of the tube.

Abstract: A fixture is provided for retaining radiators for repair and/or replacement of radiator tanks and/or cores. A frame is provided with a pair of jaws, one of the jaws being movable manually and by means of a driving element to secure a radiator between the jaws. Guideways are provided in the frame for a crimping tool which is slidable along the guideways to effect crimping of the tabs to secure the radiator header to the tank. A pivotable assembly is disposed above the jaws with air cylinders and pistons for retaining the radiator tank in engagement with the core.

Abstract: An improved tube and fin heat exchanger and a method and apparatus for making the same is disclosed. The heat exchanger includes spaced end sheets and a stack of plate fins positioned therebetween. Hairpin tubes extend through the end plates and the stack of fins. The tubes are initially sized to loosely fit through the end sheets and fins and are expanded into tight heat exchange engagement therewith during manufacture. The end sheets are accurately positioned a fixed distance apart by a method and apparatus in which the end sheets are held a fixed distance apart during the expansion of the tubes. The bent ends of the hairpin tubes are moved upwardly through the adjacent end sheet and the fins ahead of the expansion bullets to compensate for the shortening of the tubes created by the expansion operation.

Abstract: An automated heat exchanger tube expander includes an automatically adjustable tool stop, an automatically adjustable back support, and a universal base support. The adjustable stop, the back support, and the base support function together to facilitate the manufacturing of various size tube and fin heat exchangers. The automatic tube expander avoids the time consuming set up for each different size heat exchanger normally required by manual tube expanders.

Abstract: Both an apparatus and method for plugging a conduit, such as a tube in the tubesheet of a nuclear steam generator, is disclosed herein. The plugging apparatus generally comprises an inelastically expandable plug that contains a fluid-receiving cavity, and an expansion means including both a source of pressurized hydraulic fluid and a pull-rod member having a piston for advantageously applying both a radially expansive force and a compressive force to the plug at the same time in order to inelastically expand it into sealing engagement with the inner wall of a tube. In the apparatus of the invention, the compressive force exerted on the plug by the pull-rod member not only serves to inelastically deform the plug into a radially expanded shape, but is also used to seal the open end of the plug so that the pressurized hydraulic fluid admitted within the cavity of the plug will not escape.

Abstract: A method and apparatus for facilitating removal of spent tubes from boilers or heat exchangers in environments where access to one side of the wall through which the tube extends is limited. The apparatus includes a jaw assembly that is movable between a retracted position, at which it can be introduced within a tube to be removed, and an expanded position, at which it radially expands the tube so as to prevent longitudinal movement of the tube. The jaw assembly can be manipulated between the retracted and expanded positions solely through the tube interior so that a worker stationed at a proximal end of the tube to be removed can move the jaw assembly to the expanded position at which the distal end of the tube is fixed against longitudinal movement. After application of pulling forces to fracture the tube, the jaw assembly can be disengaged solely by access through the tube from the proximal end, whereby efficiency of tube removal in environments of limited access is materially enchanced.

Abstract: An improved system for removing a plug from the open end of a heat exchanger tube in a nuclear steam generator is disclosed herein. It is particularly adapted for removing a plug formed from an elongated, cylindrical shell of Inconel.RTM. having a closed end, an open ends, and an expander element that radially expands the shell when axially drawn from the clossed to the open end of the shell. The system comprises an expander remover for axially pushing the expander element from the open end completely through the closed end of the plug shell, and a TIG torch for creating beads along the longitudinal axis of the plug shell which relax the engagement between the plug shell and the tube after the weld beams harden. Finally, the system includes a plug puller for pulling the loosened plug from the tube.

Abstract: An apparatus for securing straight tubes between two tube sheets in a pressure-tight manner, especially in the manufacture of heat exchangers. Tubes are inserted, with play, in bores of the tube sheets. One end of each tube is hydraulically expanded via a pressure medium to thereby press this one end against the associated tube sheet. The one end is secured to the associated tube sheet, preferably by being welded thereto. Each tube is heated in conformity with a prescribed prestress that is to be produced in secured ones of the tube to take into account subsequent operation conditions to push a portion of the non-secured other end of the tube out of its associated tube sheet until a predetermined difference in length between the cold and heated-up states of the tube is pushed out.

Abstract: A method and apparatus for belling and expanding the tubes of a plate fin heat exchanger that involves a gripper for gripping the tube during the belling operation and a clamp for clamping a tube sheet during the tension expanding operation.

Abstract: An extractor for pulling individual tubes from a tube sheet in a heat exchanger. The extractor includes a pair of serrated, drive wheels or drivers mounted in a housing on parallel rotating shafts. The tube drivers have inclined teeth which project into opposite sides of a passageway along which a tube is drawn. The spacing between the drivers is adjustable to accommodate different sized tubes, and the drivers are spring biased towards each other, to provide a constant gripping force on a tube within the passageway. The drivers are respectively rotated by two hydraulic motors, with the hydraulic power supply connected in series, thereby providing substantially synchronous rotation of the drivers.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree. and the ends of the first row of the coil contacts a portion of the platen causing the formation of a knob at the end of each coil.

Abstract: To an elongate body (1) having preferably an adjustable length, seals (2, 3) are fixed. The seals comprise a skirt (22) forming a crown which surrounds a body portion at a small distance from the surface thereof, the skirt being made of a material having a flexibility sufficient to be slightly reduced in diameter when the tool is introduced into a tubular element to be expanded. The skirts of the two seals may be interconnected, thus outwardly delimiting an internal ring-shaped chamber (20) intended to receive an expansion fluid.

Abstract: A mechanical plug (20) having internal threads (24) and displaceable cone (30) for expanding the plug into secure engagement with a steam generator tube (14) is removed by a method which includes the step of moving the cone (30) upwardly within an internal cavity (22) along tapered surface (26), stretching the plug and thereby reducing its diameter by means of a tube stretcher 40 having an internally and externally threaded adapter (42), a bolt-like expander (50) and a force pad (52), and, pulling the plug from the tube.

Abstract: A method and apparatus for securing straight tubes between two tube sheets in a pressure-tight manner, especially in the manufacture of heat exchangers. Tubes are inserted, with play, in bores of the tube sheets. One end of each tube is hydraulically expanded via a pressure medium to thereby press this one end against the associated tube sheet. The one end is secured to the associated tube sheet, preferably by being welded thereto. Each tube is heated in conformity with a prescribed prestress that is to be produced in secured ones of the tube to take into account subsequent operating conditions to push a portion of the non-secured other end of the tube out of its associated tube sheet until a predetermined difference in length between the cold and heated-up states of the tube is pushed out.

Abstract: A tube expander capable of simultaneously applying a plurality of selected radial pressures outwardly at a plurality of sections of a tube interior to provide selected expansions of the sections of the tube.

Abstract: An improved tube and fin heat exchanger and a method and apparatus for making the same is disclosed. The head exchanger includes spaced end sheets and a stack of plate fins positioned therebetween. Hairpin tubes extend through the end plates and the stack of fins. The tubes are initially sized to loosely fit through the end sheets and fins and are expanded into tight heat exchange engagement therewith during manufacture. The end sheets are accurately positioned a fixed distance apart by a method and apparatus in which the end sheets are held a fixed distance apart during the expansion of the tubes. The bent ends of the hairpin tubes are moved upwardly through the adjacent end sheet and the fins ahead of the expansion bullets to compensate for the shortening of the tubes created by the expansion operation.

Abstract: A pressurizable tool adapted for expanding a close-fitting sleeve into a tube in a tubesheet. The tool includes a housing containing an axially movable piston and a forward reduced diameter portion and having an elastic expander unit for inserting into the sleeve and tube in a tubesheet. The expander unit consists of at least two elastic rings composed of a polyurethane elastomer material and each having a chamfer provided at the outer edge of the unit forward and rear faces. By pressurizing a port at the housing front end, the piston is moved rearwardly to axially compress and expand the expander rings radially outwardly sufficiently to expand the sleeve firmly into the tube and provide a pressure tight seal therebetween. Following such expansion of the sleeve, the piston is pressurized and moved forward to release the compression on the expander unit rings, so that the tool can be easily withdrawn from the expanded sleeve and tube and inserted into another sleeve and tube for repeated usage.

Abstract: An elongated tool device adapted for use in installing a tubular sleeve within a tube and forming a pressure-tight seal therebetween. The tool device includes a housing having a reduced-diameter forward extension portion attached to a front cylinder, and containing a rear piston. The front cylinder is attached to a collet having multiple radially expandable fingers and contains a front piston attached to a tapered mandrel which is axially movable within the fingers, and has a forward tapered nose portion to facilitate inserting the tool into a tube. The rear piston is attached to the front piston by an elongated rod. By pressurizing the tool front piston by a hydraulic fluid pressurizing unit, the mandrel is forced forward through the collet fingers to expand the fingers and sleeve tightly into the tube to form the seal joint.

Abstract: A sleeve (8) is introduced inside the tube (3) from the face (1a) of the tube plate, with which the tube (3) is flush, through the entire length of the tube plate (1). The tube (3) and the sleeve (8) are joined together in two zones (15, 16) by means of a binder which ensures a bond of high mechanical strength. An axial pull is exerted on the sleeve (8) from the face (1a) of the tube plate (1). The device is capable of pulling on the sleeve which operates either continuously or in steps.

Abstract: A rod mounting system for mounting expander rods in tube expander machines is disclosed. The mounting structure includes an opening in a header sized to receive the end of a mounting rod. A key extends into the opening from one side thereof. The rod end is provided with two longitudinally extending keyways and a peripheral groove. The first keyway extends from the end of the rod to an end face aligned with the peripheral groove. The second keyway extends from a location spaced from the end of the rod in both directions beyond the peripheral groove. The rod is installed in the header by longitudinal movement in an installation and removal orientation in which the key is aligned with the first keyway. When the rod engages the inner end of the first keyway, it is rotated to position the second keyway and the key in alignment. In such orientation, the rod is locked within the header for movement between two limits of longitudinal movement.

Abstract: An apparatus for tension expanding a plate fin heat exchanger to provide a heat exchanger with bells of the same form and dimension and then expanding the tube into contact with the tube sheets and hairpin tubes while the bells are clamped to prevent the hairpin tubes from moving.

Abstract: An apparatus for producing a high performance evaporator tube having a subsurface channel formed between adjacent helical fins with the subsurface channels having alternating closed portions and open pores above the subsurface channels. The fins of the tube are rolled-over toward the adjacent fin and then contacted with a notched disc to form the alternating closed portions and open pores.

Abstract: This invention is directed to a method of working the free end of heat exchanger tubes, and particularly the formation of braze cups, with the heat exchanger tubes in situ relative to the heat exchanger core with the method including the step of utilizing centering tooling positioned about a tube expansion rod to assure that the braze cup is centered relative to its respective tube axis.

Abstract: A method and apparatus for belling and expanding the tubes of a plate fin heat exchanger that involves a gripper for gripping the tube during the belling operation and a clamp for clamping a tube sheet during the tension expanding operation.

Abstract: When the free marginal portions 42 are telescoped within the confines of the peripheral flange 36 preparatory to the soldering operation, inward pressure on the end tank 38 usually is maintained during the soldering operation. Of course, the soldering operation involves the application of heat to both the peripheral flange 36 and the peripheral side wall 40. This sometimes will cause the free marginal portion 42 of the peripheral side wall 40 to deform inwardly away from the peripheral flange 36, thus leaving excessive spacing between the free marginal portion 42 and the peripheral flange 36. In order to avoid this condition, raised dimples 44 are formed in the header plate 34 along the peripheral flange 36 and spaced slightly inward from the latter a distance equal to the thickness of the peripheral side wall 40.

Abstract: A method and apparatus for supporting a partially formed plate fin heat exchanger at a tension expansion station and for moving the heat exchanger into and out of the expander station.

Abstract: The tube plug removal machine removes any type of tube plug by drilling into a plug portion with a tap drill bit, engaging that plug portion with a threaded section of the tap drill bit after the drilled hole has been threaded by a tapping section thereof, and removing a portion of the tube holding the plug in the tube with a counterbore drill bit mounted concentrically about the tap drill bit. A trip pin and trip spline enable the tap drill bit to be automatically disengaged from the motor once the tap drill bit has been threaded into engagement with the plug. The conterbore drill bit is thereafter self-centered with respect to the tube and plug about the now stationary tap drill bit. After a portion of the plug has been removed by the counterbore drill bit, pulling on the tap drill bit will remove the remaining plug portion from the tube.

Abstract: A bladder mandrel utilizing a sleeve of Pellethane.RTM. to effect tube expansions is disclosed herein. The sleeve which forms the bladder of the mandrel terminates in sealing beads which include fluid-capturing recesses. When the beads of the sleeve are secured within grooves provided in the mandrel body, pressurized fluid flowing through the fluid port of the mandrel enters the fluid-capturing recesses of the beads and sealingly engages these beads within their respective grooves. The sleeve consequently fills with the pressurized fluid, and effects the desired tube expansion. The walls of the sleeve are thinnest at their center portion, and become progressively thicker toward the sealing beads. The use of a Pellethane.RTM. sleeve having a centrally disposed thin-walled section results in a bladder mandrel having a relatively small outer diameter, which in turn allows it to be inserted within a tube without the need for lubricants.

Abstract: A tube expansion tool for use in expanding sleeve inserts in the repair of steam generator tubes. An inflatable bladder radially enlarges in response to application of a pressurized fluid to radially expand a repair sleeve. The bladder is mounted to a mandrel by a pair of end caps which are configured to provide a fluid tight seal to confine the pressurized fluid inside of the bladder.

Abstract: A method and apparatus for expanding in compression a portion of a plate fin heat exchanger up to a tube sheet and then gripping the expanded portion of the tube end to expand the remainder of the tube in tension and then unclamping and belling the end of the tube at a single station.

Abstract: A flexible extension assembly for use with a tube expander of the type having an expanding head which has internal apparatus driven for tube expansion by a drive device connected coaxially thereto with a spacer for locating the expanding head at a predetermined distance from the end of the tube to be expanded. The flexible extension assembly comprises a rigid hollow extension segment pivotably connected at one end to the expanding head and pivotably connected at the other end to the spacer so that the extension segment is pivotable into and out of coaxial alignment with the tube to be expanded, and an extension link slidably carried in the hollow rigid extension segment and pivotably connected at one end to the internal apparatus and pivotably connected at its other end to the drive shaft so that the extension link is pivotable with the extension segment into and out of coaxial alignment with the tube to be expanded.

Abstract: For the purpose of compressing by hammering a steam generator tube (1), there is directed a stream of gas at high velocity charged with particles having a particle size of between 50 and 500.multidot.10.sup.-6 m, onto the inner surface of the tube (1). The jet of gas is directed onto the inner surface of the tube (1) in radial directions and onto the whole of the periphery of the tube. The flow of the mass of the particles is higher than 0.008 kg/sec for tubes having an inside diameter of around 0.020 m. The device comprises a flexible sheath (20) movable inside a case (16, 18) fixed in a sealed manner under the tube plate (2) around the tube (1). An injection nozzle (21) is disposed at the end of the sheath (20) receiving the gas charged with particles.

Abstract: Heat exchanger tubes and heat pipes are simultaneously radially expanded into engagement with heat transfer fins and provided with internal spiral grooving by a generally spherical shaped tool disposed on the end of an elongated mandrel. The tool comprises a spherical segment having helical teeth formed on the exterior thereof and the tool is mounted for free rotation on the end of the mandrel. In forming a finned tube type heat exchanger a series of platelike fins are disposed in alignment with each other with tube receiving openings formed slightly oversize with respect to the outside diameter of the tube prior to expansion. The tube is supported by the fins and is secured at one end by a suitable device such as an expanding jaw collet connected to a hydraulic cylinder for extending the mandrel through the tube.

Abstract: A helical baffle for shell and tube type heat exchangers is fabricated by stamp forming a plate in the form of a partial circular section into a helical section between opposed, mating helically-shaped faces of two forming dies. The plate contains a series of apertures in the form of a pattern for receiving heat exchanger tubes. The dies contain sleeves and opposed reaming rods which form lips on the apertures during stamping of the plate. Lips can also be formed on the outer edge of the plate and the edge of a central passage during stamping. The lips prevent the helical plate from twisting or returning to a flat configuration. The leading and trailing edge of the helical plates are then joined such as by rivetting or welding into a continuous helical baffle with sets of heat exchanger tube apertures aligned along a common axis.

Abstract: An elongated tube expander tool and method for its use for remotely expanding a tube end to provide a close fit in an existing tube, such as before welding the tube end to the existing tube. The expander tool comprises an elongated central shaft attached to a cylinder which is attached to a collet having multiple expandable fingers. The cylinder contains a slidable front piston connected to a mandrel located within the collet, so that when the piston is pressurized and moved forward the multiple fingers are expanded radially outwardly within the tube end. In use, the tool is inserted into a replacement tube until a front shoulder of the tool housing contacts the replacement tube end portion to be expanded. The front piston is then pressurized and the mandrel forced axially forward through the collet so as to expand the collet fingers, which action expands the tube end firmly against the existing tube suitable for a weld to be reliably made between the closely fitting tubes.

Abstract: Apparatus for processing the damaged tubes of a steam generator. This apparatus includes a sleeving tool for inserting sleeves in the tubes, a high-roller tool for rolling the sleeves at their upper ends where they have been expanded, and a low-roller tool for rolling the sleeves at their lower ends in the tube sheet. Each tool is provided with locking pins which engage tubes adjacent to a tube to be processed and suspend the tool in processing position. The sleeves are inserted in the tubes and are rolled by rolls driven by a hydraulic motor. For sleeve insertion and for high and low rolling, the motor is controlled by a servo control valve. The feedback signal to this valve is derived from a flow transducer in the feed line for the motor. The feedback for the force of sleeve insertion is the pressure across the motor derived from pressure transducers in the conductors through which the motor is supplied. For insertion speed and for rolling speed, the feedback is derived from a fluid-flow transducer.

Abstract: Apparatus for expanding a tube into a bore formed in a tube sheet in which a tubular force-transmitting member extends within the tube coextensive with the portion of the tube to be expanded. An explosive is disposed in the bore of the force-transmitting member, so that the forces resulting from the explosion of the explosive are uniformly transferred by the force-transmitting member to expand the tube into the bore. A tubular barrier member extends between the force-transmitting member and the tube and has a portion projecting from the tube sheet, and a plug is disposed in the end of the projecting portion of the barrier member to contain the debris and gases resulting from the explosion.

Abstract: The simultaneous straightening and insertion of tubular sleeves into damaged heat exchanger tubes is accomplished by passing a pre-bent tubular sleeve through a bending apparatus utilizing three forming rolls. One of the forming rolls can selectively be moved toward the other two to compensate for varying radii of curvature. The apparatus is equipped with a pneumatic or hydraulic cylinder capable of pulling the tubular sleeve through the bending apparatus in incremental steps. By simultaneously straightening and inserting pre-bent tubular sleeves into damaged heat exchanger tubes, the tubular sleeves can be inserted into damaged tubes which are in positions which would otherwise be impossible to be repaired by this method. This method effectively circumvents the proscription of straight tube insertions into damaged heat exchanger tubes from the quarter spherical chamber of the heat exchanger.

Abstract: An apparatus and process for expanding a tube at selective points about its circumference to join another tube. After a segment of a first tube is inserted into a second tube having an end sleeve segment with a larger diameter and wall thickness than the first tube, compression and subsequent radial expansion of elastomeric bars lodged along the generally open sides of a bushing located within the first tube end segment cause the elastomeric bars to radially expand the wall of the first tube. The wall of the first tube expands at selective points against the wall of the second tube in proximity to their respective ends, creating a selective interference fit therebetween.

Abstract: A furnace heat exchanger and support plate assembly are joined together by a cooperating oval rim defining an opening in the heat exchanger and an opening formed by a mating flange on a partition plate and extending perpendicular to the plane of the plate. The flange on the partition plate is inserted in the opening in the heat exchanger unit and expanded radially outward with respect to the central longitudinal axis of the openings by a multiple jaw expander mechanism which is inserted through the opening in the plate into the interior of the heat exchanger. A second expander apparatus is inserted in the opening after withdrawal of the first expander to engage and expand portions of the flanges which were not fully displaced by the first expander. The expander mechanisms include radially and axially movable jaws comprising plural oval shaped jaw segments which are engaged by an axially movable mandrel.

Abstract: A tube positioning tool for remotely positioning a replacement tube into axial alignment and interfitting engagement with an existing tube, and method for its use. The forward end section of the elongated pressurizable tube positioning tool is first inserted through the replacement tube and into the existing tube end, after which the forward end is clamped into position therein by pressurizing the tool and expanding the tool nose end. Next, the tool body rear piston is pressurized and the replacement tube is moved forward into axial alignment and interfitting engagement with the adjacent existing tube. Then the tool body front piston is pressurized to expand a resilient mandrel and the rear portion of the replacement tube is expanded firmly into the opening in the tube sheet. Following such replacement tube installation, the tool is depressured and withdrawn from the tubes.

Abstract: Apparatus for processing the damaged tubes of a steam generator either to prepare the tubes for insertion of a sleeve, or to insert a sleeve or to treat the sleeve after it is inserted. This apparatus includes a drilling tool for drilling out plugs, a sleeving tool for inserting sleeves in the tubes, a high-roller tool for rolling the sleeves at their upper ends where they have been expanded, and a low-roller tool for rolling the sleeves at their lower ends in the tube sheet. The sleeves are inserted in the tubes and are rolled by rolls driven by a hydraulic motor. For drilling, for sleeve insertion and for high and low rolling, the motor is controlled by a servo control valve.

Abstract: An assembly machine is operable in a single continuous stroke to advance a radiator header plate having a plurality of tube receiving openings onto the ends of a plurality of radiator tubes and to forcibly peripherally expand the tube ends within the openings in the header into a press fit relationship with the header.

Abstract: Apparatus (10) for imparting protecting compressive stresses to the inside surfaces of a U-shaped heat exchanger tube (12) in order to eliminate or substantially reduce residual tensile stresses within the U-bend region of the U-shaped heat exchanger tube (12) as a result of the fabrication of the U-shaped tube (12) under cold bending techniques comprises a high-speed rotary drive motor (22), flexible drive shafts (28, 30) extending throughout the axial length of the U-bend region of the U-shaped tube (12), and shot-peening flaps (32) having tungsten-carbide shot particles secured thereto. A plurality of epicyclic gear trains (26) are axially spaced along the flexible drive shafts (28, 30) so as to cause the shot-peening flaps (32) to orbit about the interior surface of the U-bend region of the U-shaped tube (12) simultaneously with the high-speed rotary drive of the flexible drive shafts (28, 30).

Abstract: Apparatus for assembling plate and tube heat exchangers of the type having tube end portions joined to end plates includes a carriage for longitudinally carrying an assembled but unjoined heat exchanger. An upright stationary frame supports a tool holder for movement transversely of the heat exchanger longitudinal axis. The tool holder is movable so that tools carried thereby are located in facing relationship to an end plate for joining tube end portions thereto. The tool holder is also transversely movable to a clearance position for providing longitudinal movement of the heat exchanger and carriage therepast. A clamping device at the opposite end portion of the heat exchanger clamps the opposite tube end portions for holding the tubes against longitudinal and rotational movement while the other tube end portions are joined to an end plate. The clamping device is also movable transversely of the heat exchanger longitudinal axis.

Abstract: A method of manufacturing a fin-tube heat exchanger which includes a multiplicity of plate fins arranged in a plurality of rows disposed at a predetermined pitch in the direction of air flow, and a jointless refrigerant pipe extending through the plate fins in a zigzag manner. Pipe-receiving holes are formed in each plate fin in an offset manner relative to the center of the plate fin. The plate fins are then placed in fin-receiving grooves formed in a straight fin positioning fixture at predetermined spacings such that the same longitudinal ends of the plate fins of alternating rows appear on the same side of the fin positioning fixture and such that the pipe-receiving holes are linearly aligned. The refrigerant pipe is inserted into the pipe-receiving holes and is expanded to make tight and close contact with the plate fins.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. A piece of expanded metal is placed between the two rows. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen and the piece of expanded metal. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree.