Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
  • B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
  • B21C37/15—Making tubes of special shape; Making tube fittings
  • B21C37/20—Making helical or similar guides in or on tubes without removing material, e.g. by drawing same over mandrels, by pushing same through dies ; Making tubes with angled walls, ribbed tubes and tubes with decorated walls
  • B21C37/207—Making helical or similar guides in or on tubes without removing material, e.g. by drawing same over mandrels, by pushing same through dies ; Making tubes with angled walls, ribbed tubes and tubes with decorated walls with helical guides

Definitions

• the invention relates generally to a tool for fo ⁇ riing protrusions on the inner surface of a heat transfer tube and a method for using the tool.
• Heat transfer tubes having an enhanced inner surface to facilitate heat transfer from one side of the tube to the other.
• Heat transfer tubes are commonly used in equipment, such as, for example, flooded evaporators, falling film evaporators, spray evaporators, absorption chillers, condensers, direct expansion coolers, and single phase coolers and heaters, used in the refrigeration, chemical, petrochemical, and food-processing industries.
• a variety of heat transfer mediums may be used in these applications, including, but not limited to, pure water, a water glycol mixture, any type of refrigerant (such as R-22, R-134a, R-123, etc.), ammonia, petrochemical fluids, and other mixtures.
• An ideal heat transfer tube would allow heat to flow completely uninhibited from the interior of the tube to the exterior of the tube and vice versa.
• free flow of heat across the tube is generally thwarted by the resistance to heat transfer.
• the overall resistance of the tube to heat transfer is calculated by adding the individual resistances from the outside to the inside of the tube or vice versa.
• tube manufacturers HaVe'Sought to uncover ways to reduce the overall resistance of the tube.
• One such way is to enhance the outer surface of the tube, such as by forming fins on the outer surface. As a result of recent advances in enhancing the outer tube surface (see, e.g., U.S. Patent Nos.
• Patent No. 3,753,364 discloses forming a continuous groove along the inner surface of a tube using a cutting tool that cuts into the inner tube surface and folds the material upwardly to form the continuous groove.
• Manufacturing heat transfer tubes using known cutting tools can be a delicate and often expensive endeavor. Generally, these tools incorporate cutting bits that are always exposed. Thus, as the tool enters the tube, it easily can be damaged. Additionally, known tools can also be damaged when finning is stopped, then restarted. These tools often get stuck in the groove created between the finned section and the smooth section of the tube. While the tools described above aim to form the desired surface on a heat transfer tube, there remains a need in the industry to continue to improve upon known tools by modifying existing and creating new tools that enhance heat transfer performance.
• This invention provides an improved tool and method for enhancing the heat transfer performance of tubes used in at least all of the above-referenced applications (i.e., flooded evaporators, falling film evaporators, spray evaporators, absorption chillers, condensers, direct expansion coolers and single phase coolers and heaters, used in the refrigeration, chemical, petrochemical and food-processing industries).
• the inner surface of the tube is enhanced with a plurality of protrusions that significantly reduce tube-side resistance and improve overall heat transfer performance.
• protrusions in accordance with this invention can result in the formation of up to five times more surface area along the inner surface of the tube than with simple ridges.
• Certain embodiments of the invention include using a tool, which can be easily added to existing manufacturing equipment, having a cutting edge to cut through the surface of the tube and a lifting edge to lift the surface of the tube to form protrusions. In this way, protrusions are formed without removal of metal from the inner surface of the tube, thereby eliminating debris that can damage the equipment in which the tubes are used.
• Other embodiments of the invention include a tool for cutting the inner surface of a tube.
• the tool includes a tool axis and at least one tip formed by the intersection of at least a first plane, a second plane and a third plane, and has a cutting edge and a lifting edge.
• the tool also includes a housing, a spacer and a spring.
• the spacer applies pressure to a surface of the at least one cutting bit adjacent to the tip and causes the at least one cutting bit to protrude from the housing when frictional or axial forces are exerted on the spacer.
• the spring is adjacent to a base end of the cutting bit. The spring extends when the forces relax and allows the at least one cutting bit to retract within the housing.
• Other embodiments of the invention include a tool for cutting the inner surface of a tube.
• the tool includes at least one cutting bit with a tool axis and at least one tip formed by the intersection of at least a first plane, a second plane and third plane, and has a cutting edge and a lifting edge.
• the method includes mounting a tool onto a shaft, positioning the tool in the tube and causing relative rotation and relative axial movement between the tube and the tool to cut at least partially through at least one ridge formed along the surface of the tube to form ridge layers and subsequently lifting the ridge layers to form protrusions.
• the tool preferably includes a tool axis and at least one cutting bit formed by the intersection of at least a first plane, a second plane, and a third plane and has a cutting edge and a lifting edge.
• the tool also includes a housing, a spacer and a spring.
• the spacer applies pressure to a surface of the at least one cutting bit adjacent to the tip and causes the at least one cutting bit to protrude from the housing when frictional or axial forces are exerted on the spacer.
• the spring is adjacent to a base end of the cutting bit. The spring extends when the forces relax and allows the at least one cutting bit to retract within the housing.
• the cutting edge is formed by the intersection of the first and second planes.
• the lifting edge is formed by the intersection of the first and third planes.
• the second plane is oriented at an angle relative to a plane perpendicular to the tool axis. In a particular embodiment, the second plane is oriented at an angle between approximately 40° and 70° relative to the plane perpendicular to the tool axis. In a more particular embodiment, the second plane is oriented at an angle such that the cutting edge slices through ridges on a tube surface at an angle between approximately 20° and 50° relative to the plane perpendicular to the tool axis. In yet another embodiment, the third plane is oriented at an angle relative to a plane perpendicular to the tool axis.
• the third plane is oriented at an angle between approximately -45° and 45° relative to the plane perpendicular to the tool axis.
• "hi a , fu ⁇ he' i r' rnbo l dfmerit , ; ;" l th ⁇ cutting edge slices through ridges on an inner surface of the tube at angle between 20° and 50° to create a plurality of protrusions.
• the lifting edge lifts the plurality of protrusions at an angle of inclination relative to a plane perpendicular to a longitudinal axis of the tube.
• the lifting edge lifts the protrusions at approximately -45° and 45° relative to the plane perpendicular to the tool axis.
• the tube moves rotationally and axially relative to the tool when the tool is used to cut the inner surface of the tube.
• the relative rotation and relative axial movement between the tube and the tool causes the at least one cutting bit to protrude outwardly from the housing.
• stopping the relative rotation and relative axial movement between the tube and the tool causes the at least one cutting bit to retract inwardly into the housing.
• the cutting edge slices through ridges on an inner surface of the tube at angle between 20° and 50° to create a plurality of protrusions.
• FIG. 1 is a perspective view of tool according to an embodiment of the invention.
• Figure 2 is a side view of the tool of Figure 1.
• Figure 3 is a side sectional view of tool according to an embodiment of the invention.
• Figure 4A is a side elevation view of a cutting bit to be used with a tool according to an embodiment of the invention.
• FIGS. 1A and FIGS. 1A are views of the cutting bit of Figure 4A.
• Figure 4C is a perspective view of the cutting bit of 4A.
• Figure 5 is a side elevation view of manufacturing equipment incorporating an embodiment of the tool of this invention.
• Figure 6 is a perspective view of the equipment of Figure 6.
• DETAILED DESCRIPTION OF THE INVENTION In order to increase the surface area of the inner diameter of a heat transfer tube, a pattern may be formed on the inner surface of the tube. Protrusions are commonly used for this purpose. One method of forming protrusions involves first forming ridges on the inner surface. The ridges are then cut to create ridge layers, which are subsequently lifted up to form protrusions. This cutting and lifting may be accomplished using tool 10. As shown in FIGS.
• tool 10 includes housing 12 and at least one cutting bit 28.
• the cutting bits 28 are retractable within the housing 12.
• Tool 10 preferably incorporates shaft 14, which may be connected to a rod (not shown).
• the tool 10 includes multiple cutting bits 28.
• the tool 10 includes at least four cutting bits 28, although only two are visible.
• cutting bits 28 are held in place in part by ring 20.
• Ring 20 also holds the cutting bit close to the sliding plane 36 of the shaft 14.
• the tool 10 further includes a spring 24 for retracting the cutting bit(s) 28.
• the spring 24 may be a flat, disc or coil spring. As one with skill in the art will understand, any material that can be compressed and expanded, such as rubber may be used in place of spring 24.
• Spring 24 is preferably separated from the cutting bits 28 by a washer 22, which allows the spring 24 to exert pressure evenly on the cutting bits 28 without sliding over the cutting bits 28.
• Spacer 18 may be used to prevent pressure from coil spring 24 from damaging housing 12.
• Spacer ⁇ ' 8 ' may be l, ''att
• Screw 16 may be used to secure tool 10 onto shaft 14. Screw 16 is used to manipulate the maximum diameter the cutting bits 28 protrude from housing 12. In some embodiments, screw 16 is a finely threaded screw. Screw 16 may serve as a way to adjust the maximum cutting bit diameter while the bits are fully extended.
• Housing 12 protects cutting bits 28 when tool 10 is not in use. Additionally, housing 12 works with ring 20, spacer 18 and screw 16 to hold bits 28 in place. In some embodiments, housing 12 is comprised of two separate parts 56, 58. This allows easy accessibility to the individual tool components. It also allows different cutting bits 28 to be used in one tool 10. For example, cutting bit 28 with tips with a particular profile can be used for a period of time, then cutting bit 28 with tips for a different profile can be used in the same tool 10. When a two part housing 12 is used, cutting bit 28 can easily be replaced if it becomes worn or broken.
• tool 10 may be used to cut through ridges and lift the resulting ridge layers to form protrusions.
• Tool 10 includes cutting bits 28 that are retractable within housing 12.
• Cutting bits 28 can be made from any material having the structural integrity to withstand metal cutting (e.g. steel, carbide, ceramic, etc.), but are preferably made of a carbide.
• An embodiment of a cutting bit 28 that may be used with tool 10 is shown in Figs. 4A-C.
• the cutting bit 28 shown in FIGS. 4A-C generally has an axis q, two base walls 40, 42 and one or more side walls 44. Tip 30 is formed on side walls 44 of cutting bit 28.
• each tip 30 need not be the same for tips 30 on a single cutting bit 28. Rather, tips 30 having different geometries to form protrusions having different shapes, orientations, and other geometries may be provided on cutting bit 28. Moreover, any number of cutting bits 28 may be used with tool 10 depending on the desired pitch P 8jP of protrusions.
• Each tip 30 of cutting bit 28 is formed by the intersection of planes A, B, and C. The intersection of planes A and B form cutting edge 32 that cuts through ridges to form ridge layers. Plane B is oriented at an angle ⁇ relative to a plane perpendicular to the tool axis q
• Angle ⁇ is defined as 90°- ⁇ .
• angle ⁇ is preferably between
• angle ⁇ i angle ⁇ , and thus angle ⁇ i on cutting bit 28 can be adjusted to directly impact the angle of inclination ⁇ of protrusions.
• the angle of inclination ⁇ (and angle q>j) is preferably the absolute value of any angle between approximately -45° to 45° relative to the plane perpendicular to the longitudinal axis s of tube 62.
• protrusions can be aligned with the plane perpendicular to the longitudinal axis s of tube or incline to the left and right relative to the plane perpendicular to the longitudinal axis s of b 1 : More ⁇ Ver ⁇ 'the 1 fips' l "3 l 0'ca'rl'be J formed to have different geometries (i.e., angle (pi may be different on different tips 30), and thus the protrusions within tube may incline at different angles (or not at all) and in different directions relative to the plane perpendicular to the longitudinal axis s of tube. While preferred ranges of values for the physical dimensions of protrusions have been identified, one skilled in the art will recognize that the physical dimensions of cutting bit 28 may be modified to impact the physical dimensions of resulting protrusions. For example,
• t is the cutting depth
• ⁇ is the angle between plane B and a plane perpendicular to tool axis q
• ⁇ is the angle at which the ridge layers are cut relative to the longitudinal axis s of the tube.
• FIGS. 5 and 6 illustrate one possible manufacturing set-up for enhancing the surfaces of tube 62. These figures are in no way intended to limit the process by which tubes in accordance with this invention are manufactured, but rather any tube manufacturing process using any suitable equipment or configuration of equipment may be used.
• the tubes 62 may be made from a variety of materials possessing suitable physical properties including structural integrity, malleability, and plasticity, such as, for example, copper and copper alloys, aluminum and aluminum alloys, brass, titanium, steel, and stainless steel.
• FIGS. 5 and 6 illustrate three arbors 60 operating on tube 62 to enhance the outer surface of tube 62. Note that one of the arbors has been omitted from FIG. 5.
• Each arbor 60 includes a tool setup having finning disks 64 which radially extrude from one to multiple start outside fins having axial pitch P 3j0 .
• the tool set-up may include additional disks, such as notching or flattening disks, to further enhance the outer surface of tube.
• a mandrel shaft 14 onto which mandrel 66 is rotatably mounted extends into tube 62.
• Tool 10 also is mounted onto shaft 14.
• Bolt or retaining screw 52 secures tool 10 in place.
• Tool 10 is preferably locked in rotation with shaft 14 by any suitable means.
• tube 62 generally rotates as it moves through the manufacttiring process.
• Tube wall 68 moves between mandrel 66 and firming disks 64, which exert pressure on tube Val ⁇ 'dS:" ' ' U '*
• Tool 10 uses the frictional forces of finning to advance cutting bits 28 from within housing 12. When arbors 60 are used, pressure is exerted against tube walls 68. The friction created by the pressure and the movement of the tube 62 in relation to the tool 10 creates an axial force on spacer 18, which advances cutting bits 28 radially and compresses spring 24.
• a desirable inner surface pattern includes ridges. After formation of ridges on inner surface of tube 62, tube 62 encounters tool 10 positioned adjacent and downstream mandrel 66. As explained previously, the cutting edge(s) 32 of cutting bit 28 of tool 10 cuts through ridges to form ridge layers. Lifting edge(s) 34 of cutting bit 28 of tool 10 then lift ridge layers to form protrusions.
• tube 62 When protrusions are formed simultaneously with outside finning and tool 10 is fixed (i.e., not rotating or moving axially), tube 62 automatically rotates and has an axial movement.
• P a>0 is the axial pitch of outside fins
• Z 0 is the number of fin starts on the outer diameter of tube
• Z is the number of tips on tool.
• the necessary rotation (in revolutions per minute (RPM)) of the tool 10 can be calculated using the following formula:
• RPM tube is the frequency of rotation of tube
• P a 0 is the axial pitch of outer fins
• Z 0 is the number of fin starts on the outer diameter of tube
• P a>p is the desirable axial pitch of protrusions
• Z is the number of tips on tool. If the result of this calculation is negative, then tool 10 should rotate in the same direction of tube 62 to obtain the desired pitch P a;P . Alternatively, if the result of this calculation is positive, then tool 10 should rotate in the opposite direction of tube 62 to obtain the desired pitch P S ⁇ P . Note that while formation of protrusions is shown in the same operation as formation of ridges, protrusions may be produced in a separate operation from finning using a tube with pre-formed inner ridges. This would generally require an assembly to rotate tool 10 or tube

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Turning (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)
• Mechanical Pencils And Projecting And Retracting Systems Therefor, And Multi-System Writing Instruments (AREA)
• Walking Sticks, Umbrellas, And Fans (AREA)
• Earth Drilling (AREA)
• Making Paper Articles (AREA)
• Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
• Ladders (AREA)

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• 2005
  • 2005-05-13 MX MXPA06013048A patent/MXPA06013048A/es active IP Right Grant
  • 2005-05-13 DE DE602005022192T patent/DE602005022192D1/de active Active
  • 2005-05-13 AT AT05749473T patent/ATE473411T1/de active
  • 2005-05-13 JP JP2007513443A patent/JP4928445B2/ja active Active
  • 2005-05-13 PT PT05749473T patent/PT1766315E/pt unknown
  • 2005-05-13 CA CA002566792A patent/CA2566792A1/en not_active Abandoned
  • 2005-05-13 TW TW094115522A patent/TWI291905B/zh not_active IP Right Cessation
  • 2005-05-13 WO PCT/US2005/016963 patent/WO2005114086A2/en active Application Filing
  • 2005-05-13 EP EP05749473A patent/EP1766315B1/de active Active
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• 2006
  • 2006-10-23 IL IL178806A patent/IL178806A/en not_active IP Right Cessation

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