Air conditioners and heat pumps commonly employ vapor-compression refrigerant systems to cool, or both cool and heat air supplied to a climate controlled comfort zone within, for example, a residence, office building, hospital, school, restaurant or other facility. Conventionally, such vapor-compression systems include a compressor, condenser, an expansion device, and an evaporator connected to one another by refrigerant lines in a closed refrigerant circuit and arranged according to the vapor-compression cycle employed (i.e. heating or cooling). The condenser and the evaporator include a heat exchanger that generally acts to add heat to or remove heat from refrigerant flowing through the devices.
Heat exchangers employed in condensers and evaporators commonly include a number of coils through which the refrigerant flows, fins connecting adjacent coils to one another, and manifolds for delivering the refrigerant to the coils. The coils may be stacked vertically or horizontally in generally parallel relationship to one another and be connected between an input manifold and an output manifold. The manifolds, sometimes referred to as headers, may be, for example, closed ended tubes configured as inlet and outlet paths for refrigerant flowing to and from the coils. Pairs of adjacent coils are connected by a number of fins distributed longitudinally between the coils. The fins structurally join the coils, as well as direct air across the coils and facilitate heat transfer between the coils and the air passing over the coils. The fins are commonly constructed from a thin piece of thermally conductive material stamped into the desired shape and cut to fit the coils of the particular heat exchanger. For example, the fins may be formed from a thin piece of sheet metal that is stamped to form a number of corrugations across the length of the sheet. The corrugated sheet may then be cut into strips, each of which may form the fins joining two adjacent heat exchanger coils.
In order to stamp the sheet metal stock into the desired fin shape, the metal must be lubricated. Prior techniques commonly lubricated the fin stock by feeding the stock through an oil bath and one or more rollers in an attempt to spread the oil evenly across the stock with a desired thickness. Such techniques are directed at removing excess oil from the stock instead of applying the correct amount of oil distributed over the stock at the correct thickness. Oil bath techniques have proven unreliable at lubricant film thicknesses less than approximately 0.0254 mm (0.001 inches). Additionally, these techniques inherently produce a significant amount of waste, as well as provide little to no control over the application process.
Exemplary embodiments of the present invention include a lubrication system for heat exchanger fin stock. A head is configured to receive the fin stock. A strip of material is connected to the head and configured to absorb a lubricant and wipe the lubricant onto a surface of the fin stock. An actuator is configured to move the head into and out of engagement with the fin stock.
Exemplary embodiments of the present invention include a system for manufacturing heat exchanger fins from sheet stock. A die is configured to form the fins from the sheet stock. An uncoiler is configured to feed the sheet stock to the die. A lubrication system is interposed between the die and the uncoiler. The lubrication system includes a head configured to receive the sheet stock, a strip of material connected to the head, and an actuator configured to move the head into and out of engagement with the sheet stock. The strip of material is configured to absorb a lubricant and wipe the lubricant onto a surface of the sheet stock as it is fed from the uncoiler to the die.
Exemplary embodiments of the present invention include a method of lubricating sheet stock used to manufacture heat exchanger fins. A lubricant is delivered to a strip of material at a number of locations to substantially saturate the strip of material with the lubricant. A surface of the sheet stock is wiped with the strip of material saturated with the lubricant. A volume of the lubricant delivered to and a frequency at which the lubricant is delivered to the strip of material is controlled.
Referring again to
Lower jaw 32 includes mounting blocks 32a, orifice block 32b, felt channel 32c, and one felt strip 46. Mounting blocks 32a are connected to base 30 and to orifice block 32b. Orifices 44 are connected to and distributed approximately equally across the length of orifice block 32b. For example, the spacing of orifices 44 may range from about 50.8 mm (2 inches) to about 76.2 mm (3 inches). In one exemplary embodiment, twelve orifices 44 are distributed across orifice block 32b, spaced about 76.2 mm (3 inches) apart. In another exemplary embodiment, eighteen orifices 44 are distributed across orifice block 32b, spaced about 50.8 mm (2 inches) apart. Felt channel 32c is connected to orifice block 32b and felt strip 46 is mounted in felt channel 32c. Orifices 44 are arranged to deliver lubricant through orifice block 32b and felt channel 32c to felt strip 46. Upper jaw includes mounting bar 34a, orifice block 34b, felt channel 34c, and one felt strip 46. Mounting bar 32a is connected between actuators 36 and to orifice block 34b. Orifices 44 are connected to and distributed approximately equally across the length of orifice block 34b. Felt channel 34c is connected to orifice block 34b and felt strip 46 is mounted in felt channel 34c. Orifices 44 are arranged to deliver lubricant through orifice block 34b and felt channel 34c to felt strip 46. Orifices 44 in upper and lower jaws 34, 32 can be spaced in standard increments including, for example, 50.8 mm (2 inches) or 76.2 mm (3 inches) between each adjacent orifice 44. Orifices 44 can be spaced apart at increments to allow for even distribution of the lubricant through felt channel 34c and felt strip 46 so that lubricant is wiped evenly onto top surface 18T and bottom surface 18B of sheet metal stock 18. While exemplary embodiments have spacing between about 50.8 mm (2 inches) and about 76.2 mm (3 inches) between adjacent orifices 44, the spacing can vary depending on the type of felt used in felt strip 46 and the desired lubricant film thickness applied to sheet metal stock 18.
Actuators 36 can be, for example, pneumatic linear actuators each of which includes pneumatic cylinder 36a, linear slide 36b, and mounting plate 36c. Mounting plate 36c is connected to mounting bar 34a of upper jaw 34. Linear slide 36b is connected to base 30 and mounting plate 36c. Cylinder 36a is operatively connected to linear slide 36b. Pressurized air can be delivered to cylinder 36a through air supply 48 at a first pressure to, for example, raise cylinder 36a. Cylinder 36a raises linear slide 36b, which in turn raises mounting plate 36c thereby raising upper jaw 34. Similarly, pressurized air can be delivered to cylinder 36a through air supply 50 at a second pressure to, for example, lower cylinder 36a. Cylinder 36a lowers linear slide 36b, which in turn lowers mounting plate 36c thereby lowering upper jaw 34. Linear slide 36b can include, as generally shown in
First manifold 38 and second manifolds 40 are connected to base 30. In one exemplary embodiment, four second manifolds 40 are connected to base 30. In another exemplary embodiment, six second manifolds 40 are connected to base 30. The location of and component to which first and second manifolds 38, 40 are connected can vary depending on, for example, space constraints of the manufacturing system in which lubrication system 16 is employed. Alternative embodiments therefore include lubrication systems with manifolds mounted to, for example, upper jaw 34. Additionally, alternative embodiments can have more or fewer manifolds including, for example, a single manifold configured to split the lubricant supply into a number of lines for delivery to orifices 44 and thereby felt strips 46. Lubricant supply 52 is connected to first manifold 38. First manifold 38 splits lubricant supply four ways and delivers the lubricant through supply lines 42 to second manifolds 40. Each of second manifolds 40 splits the lubricant supplied from first manifold 38 six ways and delivers the lubricant through supply lines 42 to six orifices 44. The split configuration and the number of orifices 44 supplied by each second manifold 40 can vary depending on the number of second manifolds 40 and the number of orifices 44. Two of second manifolds 40 deliver lubricant to orifices 44 on upper jaw 34 and two of second manifolds 40 deliver lubricant to orifices 44 on lower jaw 32.
During operation as sheet metal stock 18 is fed through lubricating head 20, lower jaw 32 remains stationary and actuators 36 lower upper jaw 34 into engagement with stock 18. Lowering upper jaw 34 sandwiches stock 18 between upper and lower jaws 34, 32 and thereby two felt strips 46. Linear actuators 36 are configured to press upper jaw 34 against sheet metal stock 18 at a prescribed pressure, e.g., the second pressure described above. Lubricant is delivered by lubricant supply 52 to first manifold 38. First manifold 38 delivers the lubricant through supply lines 42 to second manifolds 40. Second manifolds deliver the lubricant, again through supply lines 42, to orifices 44 in orifice blocks 34b, 32b, in upper and lower jaws 34, 32. Orifices 44 are configured to deliver a metered amount of lubricant through orifice blocks 34b, 32b and felt channels 34c, 32c to felt strips 46. Felt strips 46 naturally wick the lubricant from the injection sites of orifices 44 to substantially saturate all of felt strips 46 with the lubricant. As sheet metal stock 18 is fed from uncoiler 14 to die stamping press 12 through lubricating head 20, felt strips 46 wipe the lubricant onto top surface 18T and bottom surface 18B of stock 18. One type of felt appropriate for use with embodiments of the present invention is F3 veined felt manufactured by US Felt Company Inc. of Sanford, Me. The F3 veined felt is manufactured to include individual strings or thread strands interspersed throughout the felt material. In arranging felt strips 46 made from F3 veined felt, the felt should be cut and positioned such that the strings are oriented approximately perpendicular to the surface being lubricated, i.e., to top surface 18T and bottom surface 18B of sheet metal stock 18. Another type of felt appropriate for use with embodiments of the present invention is F2 veined felt.
Lubricating head 20 is lowered and raised into and out of engagement with sheet metal stock 18 (shown in
In
Lubricant supply system 22 is connected to and configured to deliver lubricant to lubricating head 20. Lubricant supply system 22 includes bulk reservoir 74, solenoid valve 76, ready reservoir 78, reservoir refill switch 80, pump 82, and lubricant pressure switch 84, and third regulator 86 and solenoid valve 88. In
Plant air supply 72 is not only connected to pneumatic system 60, but also to lubricant supply system 22. As shown in
As illustrated in
Embodiments of the present invention have several advantages over prior lubrication systems and methods used on heat exchanger fin sheet stock. Instead of being directed at removing excess oil from the stock, embodiments of the present invention apply the correct amount of oil distributed over the stock at the correct thickness. Lubrication systems and methods according to the present invention are therefore less prone to excessive lubricant waste and have greater effectiveness at thinner lubricant film thicknesses including, for example, film thicknesses less than approximately 0.0254 mm (0.001 inches). Embodiments of the present invention provide a significantly improved degree of control over the lubrication process by providing direct control over lubricant volume and pressure, as well as the frequency at which the lubricant is delivered to the lubricating head.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
This application claims priority from U.S. Provisional Application Ser. No. 61/105,285, filed Oct. 14, 2008.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2009/060341 | 10/12/2009 | WO | 00 | 4/13/2011 |
Publishing Document | Publishing Date | Country | Kind |
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WO2010/045142 | 4/22/2010 | WO | A |
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Number | Date | Country | |
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20110197643 A1 | Aug 2011 | US |
Number | Date | Country | |
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61105285 | Oct 2008 | US |