Patent Grant
8667683
The present invention is directed to methods and apparatus for assembling and permanently fixturing the tubes and baffles of a shell and tube-type heat exchanger.
Tube-type heat exchangers include a plurality of tubes of substantially uniform length and a plurality of truncated, perforated baffles through which the tubes pass. Such assembled tube and baffle arrangements are referred to herein as a “bundle assembly.” Tube and baffle bundle assemblies can be assembled manually and/or automatically. Whether assembled manually, automatically, or by combination of manual and automatic methods, the resulting bundle assembly must conform to a predetermined desired shape, size, and configuration. This is because, after full assembly, the bundle assembly is typically inserted into a heat exchanger shell having predetermined fixed internal dimensions and overall length, such as in the shell of an oil cooler in a vehicle. Any significant deviation in the dimensions of the finished bundle assembly can prevent proper fit and proper function of the assembly within the heat exchanger shell.
Automatic tube assembly machines of the type with which this invention is used are illustrated in commonly owned U.S. Pat. Nos. 3,789,479 and 4,785,518. Such machines include, for example, a tube and baffle holding fixture mounted on a work table having capacity for selected vertical and horizontal movements. Two opposing sets of retractable guide rods advance successively selected quantities of tubes from a supply to the fixture, the individual rods of each set being aligned with corresponding rods of the opposing set. The machine includes means automatically operative to actuate the guide rods to advance the selected quantities of tubes from the supply to the fixture, means automatically operative to adjust the work table vertically and horizontally, following each transfer of tubes, to prepare for the transfer of the next selected quantity of tubes, and control means governing the movements of the guide rods and the work table. In this manner, tubes can be accurately and efficiently inserted to penetrate through one or more baffles in series, thereby forming a bundle assembly having a preselected configuration and dimension.
In some bundle assemblies, the perforated baffles are constituted of relatively thin, rigid metal sheets well adapted to withstand, without distortion of movement, the axial forces occurring as a result of the penetrations of the guide rods and the tubes back and forth through the baffle apertures during assembly of the bundle assembly. However, in some installations, it is preferred that the baffles be constituted of a non-metallic material, such as a relatively soft, pliable or flexible gasket-like composite material, referred to herein as “composite baffles”, which is readily bendable or otherwise distortable when subjected to relatively minor degrees of force. In forming the perforations in such composite baffles, the dies utilized for stamping the perforations in metal baffles also are used for forming the perforations in the composite baffles. Following stamping, the perforations or holes in the composite baffles have a tendency to change diameter-wise. Such phenomenon, while not at all undesirable as far as the completed heat exchanger bundle assembly is concerned, renders difficult the assembly of its tubes and baffles.
Additionally, in some installations, it is preferred that the baffles be constituted of a tough, rigid, high-strength amorphous thermoplastic. Following molding of the baffle, the holes in the baffle have a tendency to change in a diameterwise manner. In the case of amorphous thermoplastic baffles, the variation is generally predictable, and therefore, the baffle design includes holes that are oversized to accommodate the material movement without producing a surface to surface or interference fit with the tubes in the assembly process. Such phenomenon renders difficult the movement of in-process bundle assemblies in the manufacturing process and cured heat exchanger assemblies in transit between the heat exchanger assembly process, and also in the processes used to join the heat exchanger bundle assemblies with the shell.
Because of the flexible character of composite baffles, and because of the tendency of their perforations to dimensionally change, heat exchanger bundle assemblies incorporating such baffles are extremely difficult to assemble by machine and nearly impossible to assemble by hand. Because of the loose hole condition of the plastic baffles, and their effect on the dimensional and quality characteristics of the tube assembly product, bundle assemblies using plastic baffles are also difficult to fixture during the production process to match a predetermined configuration.
Additionally, once assembled, tube-type heat exchanger bundle assemblies, whether having metallic, plastic, and/or composite baffles, can easily become undesirably twisted or otherwise deformed from the desired predetermined configuration and dimensions, rendering them unsuitable for insertion into corresponding shell or housings to function as a heat exchanges such as an oil cooler, for example. Therefore, what is needed are assembly and fixturing apparatus and methods that will create and permanently preserve the desired configuration, shape and dimensions of a tube and baffle heat exchanger bundle assembly.
Lastly, it has been observed that vibration commonly encountered within a tube and baffle assembly within a heat exchanger casing may result in wear, and even cutting, of the tubes by the baffles. Thus, there is a further need for tube and baffle bundle assemblies that can withstand, and also attenuate, undesired vibrational contact between the tubes, baffles, and casing.
The primary object of this invention is to overcome the difficulties described above in assembling and permanently fixturing the tubes and baffles of a shell and tube-type heat exchanger to form a bundle assembly, whether having baffles constituted of a metal, plastic, composite, or any combination thereof.
A further object of the invention is to provide an improved baffle support fixture interchangeably useful for assembling, both manually and automatically, tubes and baffles in a bundle assembly, and that provides proper alignment of both complete and partial baffles in a desired orientation with the tubes, without undesired baffle rotation, and therefore permits the ready, efficient and quick assembly of the tubes in a bundle assembly having a plurality of complete and partial baffles disposed in a predetermined orientation with respect to one another.
A further object is to provide such an improved fixture apparatus which is adapted to be easily and quickly assembled and used, whether for manual assembly of tubes and baffles, or for installation and use on fixturing machines such as those described in U.S. Pat. Nos. 3,789,479 and 4,785,518, as well as for manual use and use with other known machines for assembling bundle assemblies, thereby enhancing the versatility and range of applicability of the fixturing apparatus.
A further object is to provide an improved baffle support fixture for assembling tubes in bundle assemblies having relatively soft and flexible baffles, as well as for use with rigid baffles, regardless of whether the baffles are composite, metal, or plastic, in which spaced vertical baffle support plates are utilized to stabilize the baffles and maintain their perforations in proper alignment during assembly of the tubes, regardless of whether assembly is by manual or automatic methods.
A further object is to provide improved apparatus and methods for permanently adhering individual rows and individual tubes to one another and to corresponding baffle portions, such as to ensure proper alignment during assembly of the tubes into the baffles, to reduce vibration and the undesirable effect of vibration. A still further object is to provide improved adhesive delivery apparatus and methods useful in performing the assembly and adhering methods.
Yet another object is to provide apparatus and methods for applying and curing of adhesive compositions useful in preserving a desired alignment and orientation of the tubes and baffles in an assembled tube and baffle bundle assembly to ensure that desired final dimensions are permanently preserved.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
a-c are side, top, and front perspective views of an adhesive dispensing tool of the present invention.
Referring first to
Reference now is made to
As shown in
In one example as further shown in
In an improvement contemplated herein, each support 28 is slidably adjustable along the bottom plate 30 to permit a user to accomplish a desired spacing between adjacent supports 28, thus permitting a desired predetermined spacing of baffles 25, 25′. In one embodiment, at least one base 29 of at least one support is slidably mounted to the bottom plate 30, with the base 29 and bottom plate 30 optionally further including means for securing the base 29 at a selected location and a selected orientation relative to the plate 30 and to other bases 29 of other supports 28. The means for securing can be any known fastening means, such as, by way of non-limiting example, set screws, tabs and corresponding grooves, spring-biased pins and corresponding apertures, and combinations thereof. The providing of such re-positionable supports 28 provides an advantage of simplifying the alignment of tube holes in each baffle 25, 25′ in a series, as well as simplifying the insertion of tubes 12 through all baffles 25, 25′ in the series. For example, where a proposed tube and baffles assembly will involve many baffles 25, 25′, the supports 28 can be positioned in very close proximity to one another to provide closely spaced baffles 25, 25′ having minimal distance therebetween, which may provide improved alignment of baffle holes by preventing an inserted tube 12 from drooping before reaching the next baffle in the series. Upon completion of insertion of all tubes through all baffles, each support 28 may then repositioned to yield a desired baffle spacing, such as by sequentially disengaging the securing means between a base 29 and the plate 30, then sliding the base 29, along with the support 29 and baffle 25, along the base 30 and the tubes until the baffle is at the desired spaced location on the assembly.
As shown in
As further shown in
As shown in
In order to prevent undesired rotation of a partial baffle 25′ during fixture assembly and during tube installation, an anti-rotational assembly 80 is provided. As shown in
Alternative anti-rotational assemblies 80 are contemplated herein, including but not limited to any dimensional feature that can be provided in an upper support 31 or lower support 32 to engage a portion of a baffle. For example, protruding tabs or pins may be provided that selectively engage the edge of a baffle 25 and/or engage at least one hole of a baffle 25 to maintain a desired orientation of the baffle 25, and to resist rotation of the baffle 25 about an axis parallel to the longitudinal axis of a tube or the desired central longitudinal axis A-A of the tube and baffle assembly to be manufactured. Alternative anti-rotational features include end walls and/or obstruction provided in the groove of the upper support 31 or lower support 32, as well as opposed tabs or clamps provided on either support 31, 32. Additionally or alternatively, an indentation can be produced in or through the baffle at its outer perimeter or circumference, such as a scallop or divot, that allows for a pin, screw, tab, or other locating device to engage and position the baffle within the fixture to maintain proper rotational orientation. Also, since amorphous plastic baffles can be produced through the use of plastic molding technology, the hole walls in the baffle may include a draft angle, which means that the walls of the hole may be tapered so that the molded part may be ejected from the mold. Since a tapered hole can be used assist the insertion of tubes or assembly rods through the bundle in both automatic or manual assembly processes, maintaining consistency of the direction of the taper can be advantageous in the assembly process, and therefore, a scallop or divot in only one side of the baffle with a pin, screw, tab, or other locating device to control the draft angle of holes when baffles are loaded into the fixture to improve the assembly process. Each anti-rotational feature 80 is disposed and configured so as to position and maintain the desired alignment of a baffle 25 or partial baffle 25′ within a series of baffles provided in a fixture support 35 for assembling of a tube and baffle heat exchanger assembly.
In automatic machine assembly methods of using the fixturing assembly 35, and as shown in
In order to maintain the baffles 25, 25′ in proper vertical alignment relative to each other, with their corresponding apertures aligned axially during penetration by the probe rods 20 as they advance to the tube supply 11, and during the retraction of those rods in cooperation with the advancing insertion rods 21, to transmit tubes 12 to the baffle supporting fixture 13 for insertion through the rows 26 of baffle apertures, a baffle stabilizing fixture 35 may be provided, as illustrated in
The imperforate plates 36a, 36b are closely spaced relative to each other, and define therebetween narrow vertical spaces or slots 38 which are slightly wider than the thickness of the two vertically aligned elements 31, 32 of the baffle supports 28 of the fixture 13. By way of example, for baffles 25, 25′ on the order of 0.1″ in thickness, the components 31, 32 of the baffle supports 28 may be 0.2″ in thickness and the spacing between each pair of baffle support plates 36a, 36b may be on the order of 0.21″ in width. The distal ends of the plates 36a, 36b of each pair of plates 36 define or provide openings for the reception or insertion of the baffles 25, 25′ into the vertical slots or spaces 38.
As illustrated in
More specifically, as the probe rods 20 advance to the tube supply 11, passing through the tube and baffle support fixture 13 and the baffle apertures aligned in the working plane 17, the pairs of plates 36 support the baffles 25, 25′ against bending or distortion, thus maintaining their verticality. Likewise, upon retraction of the guide rods 20 from the tube supply 11, in cooperation with the advancing insertion rods 21 to transmit the tubes 12 to the fixture 13, the pairs of plates 36 function to stabilize and maintain the verticality of the baffles 25, 25′ as the tubes pass through their apertures.
The forward ends 40, 41, respectively, of the guide rods 20, 21 preferably are of the usual conical configuration to permit their limited entry into the open ends of the tubes 12. Such construction ensures the firm gripping of the tubes 12 by the rods 20, 13 and ensures that the rod and the tube are accurately aligned longitudinally to each other 21 during transmittal of the tubes through the fixture. Additionally, to facilitate passage of the guide rods 20, 21 and the tubes 12 through the apertures in the soft, pliable baffles 25, 25′, each forward end 40 of a probe rod 20 has an axial length or segment 42 of reduced diameter, the inner portion of which merges into an enlarged, ball-shaped protuberance 43. The decreased diameters of the distal ends 40 of the probe rods 20 reduce friction and the degree of pressure asserted against the soft baffles 25, 25′ when those rods penetrate the apertures of successive baffles 25 as they advance to the supply 11. Further, the ball-like protuberances 43 on the guide rods 20, upon retraction of those rods from the tube supply 11, function to enlarge slightly the apertures of the baffles 25, 25′ as they pass therethrough, thereby increasing clearance for the tubes 12 advancing from the supply 11 and passing through the baffles 25. Additionally, due to the dimensional changes to the perforated holes in pierced baffles, a lubrication system that places a film of lubricant on the rods may be added to the assembly equipment to decrease friction between the rods as they pass through the baffles.
In automatic machine assembly apparatus and methods, the baffle stabilizing fixture 35 is supported and maintained in position relative to the machine 10 by a rigid superstructure indicated generally by the reference numeral 50 (
As best shown in
An elevated horizontal beam 57 extends longitudinally of the machine 10, and is connected to and supported by the horizontally spaced distal ends of the two standards 51, 52. Extending vertically downward from beam 57 are a pair of inclined, converging support arms 60, 61 which, at their junction, merge into a support bracket 62 of generally rectangular, box-like configuration. Support bracket 62 supports a pair of longitudinally spaced, hollow support bearings for mounting slidably a pair of spaced, cylindrical, axially slidable, transverse bars 65, 66. As illustrated in
If desired, superstructure 50 also may include a third vertical standard 68 located at the rear of the machine 10 and secured to the floor on which the machine rests. Standard 68 is provided with a right-angled horizontal arm 69 that extends inwardly of the machine and connects to the support bracket 62, thereby further stabilizing the rigidity of the superstructure 50. An inclined support brace 70, extending between standard 68 and its horizontal arm 69, may be provided to add further stability to the supporting structure 50.
The baffle support fixture 35 is secured in operative position relative to the tube and baffle support fixture 13 by a vertical bolt 63 extending downwardly through a central bore in support bracket 62. As illustrated in
The selected vertical and horizontal movements of the work table 14, during assembly of the tubes 12 in the fixture 13, are carried out by an actuating mechanism (not shown) of the type disclosed in U.S. Pat. No. 3,789,479 aforesaid. The table actuating means is operative to change automatically the position of the tube and baffle holding fixture 13 relative to the tube supply 11 and the guide rods 20, 21, following each deposit of tubes 12 in the fixture 13, preparatory to the next deposit of tubes therein. At the outset of the operation of the machine 10, before any tubes 12 have been deposited in fixture 13, the work table 14 is fully elevated relative to the machine and to the stationary baffle support fixture 35.
When work table 14 is fully elevated relative to fixture 35, the pairs 36 of baffle plates 36a, 36b substantially fully straddle or envelop their respective baffles 25, 25′. In such position, the working plane 17 is coincident with the lowermost rows 26 of baffle apertures, such rows being horizontally aligned, as explained previously. In practice, when the work table 14 is at its uppermost position, with the two fixtures 13, 35 properly aligned, approximately 3/16″ of the lowermost portions of the baffles 25, 25′ are exposed between the distal ends of the plates 36a, 36b and the bottom portions of the concave surfaces of the lower baffle support components 32.
As the tube assembling operation of the machine 10 proceeds, work table 14 is caused to descend vertically by successive incremental distances sufficient to bring each succeeding row 26 of baffle apertures into the working plane 17 of the machine, following which the guide rods 20, 21 deposit the selected number of tubes 12 in the aligned apertures disposed in the working plane. With each downward movement of the work table 14, a corresponding and incremental horizontal movement is imparted to the work table 14. Such movements compensate for the staggered relationship between the baffle apertures, and ensure that, in each successive adjustment of the rows 26 of the baffles 25, 25′ into the working plane 17, their apertures are properly aligned axially with the guide rods 20, 21.
A highly important advantage of this invention resides in the fact that the baffle stabilizing fixture 35 may be used manually, and may additionally or alternatively be readily installed on and removed from, an automatic assembly machine. For example, when in use on the machine 10, the fixture 35 can be installed and removed without disrupting its capacity for assembling the tubes 12 in a heat exchanger irrespective whether its baffles 25, 25′ are made of metal or of a non-metallic material, and irrespective of whether the tubes are inserted from one direction, alternate directions, and whether the tubes are inserted individually, in groups of multiple tubes simultaneously. For example, this may be achieved by the horizontal support bars 65, 66 mounted slidably internally of their respective circular bearings, illustrated by bearing 64 in
Affixed to the longitudinally spaced ends of the master plate 37 are a pair of horizontally spaced, upwardly extending, vertical arms 72, 73. Extending inwardly from the upper ends of the vertical arms 72, 73, respectively, are grooved rotatable bearings 74, 75. The two roller bearings 74, 75 are spaced apart longitudinally, and are disposed, respectively, above the horizontally slidable bars 65, 66. By reason of their grooved construction, the rotatable roller bearings or wheels 74, 75 are adapted to rest on the horizontal bars 65, 66, with capacity for rolling movement thereon, incidental to installing the fixture 35 on, or removing it from, the tube assembly machine 10.
If it is desired to remove the fixture 35, in order to utilize machine 10 for assembling metallic baffles in heat exchangers, one need only remove the threaded bolt 63, whereby fixture 35 may be lowered so that its rollers 74, 75 come into contact with, and are supported by, the horizontal bars 65, 66. With the fixture 35 now supported by bars 65, 66, the bars may be advanced slidably outwardly of the machine, to the position indicated by reference numeral 66′ in
Thus, the superstructure 50, by means of its inclined support arms 60, 61, bracket 62 and threaded bolt 63, provides a fixed supporting structure for retaining the baffle support fixture 35 in operative position relative to the tube and baffle support fixture 13 and its selectively movable work table 14. By reason of the threaded bolt 63, the horizontally slidable support bars 65, 66 and the rotatable support wheels 74, 75, the fixture 35 may be quickly assembled with the machine 10, or quickly disassembled therefrom, as required.
Permanent Fixturing of Bundle Assemblies.
Once insertion of all tubes 12 into all baffles 25, 25′ is completed, it is critically important that the tube and baffle assembly remain in its desired alignment in all dimensions. For example, as shown in
The present invention provides apparatus and methods to ensure that the desired alignments of all tubes 12 and baffles 25, 25′ are maintained, whether during assembly and containment within the fixture 35, as well as upon removal of the tube and baffle assembly from the fixture 35, and in further processing and use of the assembly. In the present invention, end plates are used to engage and secure the tubes 12 in their desired alignment, thereby also maintaining the baffles 25 in their respective desired alignment. However, “end plates” as used herein can include any structure or apparatus that maintains the end of a bundle assembly in a predetermined alignment. In one example, the present invention contemplates several types of end plates, with the only common requirement being that each end plate include surface features for engaging at least one selected tube, and/or at least one selected baffle holes and tubes 12, in a manner that prevents undesired motion of at least one tube 12 relative to another tube 12. In one example shown in
As further described herein, the end plates 90 are configured so as to exert pressure on the opposite ends of the tubes 12, the force applied along the axis A-A of the tube assembly sufficient to permit movement, such as rotation of the entire tube and baffle assembly about the axis A-A, facilitating bundle alignment without adversely altering the desired alignment of any tube 12 or baffle 25, 25′ in the assembly. Also, as previously described, the end plates 90 can be used to for parallel orientation of the end plane of the bundle assembly and the baffle closest to the end plane of the bundle assembly by using the plane of the end plate 90 (consistent with baffle axis B-B shown in
In one embodiment shown in
Next, a horizontal alignment rod 95 is threaded through a second horizontal alignment aperture 94 provided in the first end plate 90, through the corresponding tube 12, and through the corresponding horizontal alignment aperture in the second end plate (not shown). A second horizontal alignment rod 95′ is threaded through another horizontal alignment aperture 96, through the corresponding tube 12, and through the horizontal alignment aperture 96′ in the second end plate 90′. A fastener 99 is optionally applied to each of the rods 97, 95, 95′ and is tightened to maintain each plate 90 in pressured contact with the ends of at least some of the tubes 12. Optionally, as shown in
As shown in
As shown in
The apparatus of
Using the methods of the present invention, the apparatus of
In a method using end plates 90 and other apparatus of the invention, as illustrated in
In the example of
Each nozzle 132, 134 is connected to an adhesive supply source, preferably a common adhesive reservoir (not shown) provided in the applicator 130. Optionally, the adhesive reservoir may be supplied by a hose connection to an adhesive pump to allow for continuous resupply to the reservoir, thereby permitting extended adhesive application without the need to periodically manually refill the reservoir. All nozzle dimensions and ribbon dimensions are based upon 60-100 psig. Because the viscosity of the adhesive changes with the type selected as well as with its temperature, the temperature and operating pressure of the pail pump may be adjusted to compensate for variation in viscosity.
By way of further example, in addition to the nozzle configuration, delivery rate, and rotation rate, selection of the adhesive 180 is an important aspect to practice of the present invention to yield a properly aligned and properly dimensioned tube and baffle bundle assembly, and without undesirable human and environmental hazards. The inventors have found that fast-setting, non-expanding or minimal-expanding adhesives may be used to produce desirable results. For example, while nitrile rubber adhesives have been known for use in some tube assembly fixturing, rubber-based adhesives are runny and stringy, and do not set adequately to lend structural support until heat cured. Moreover rubber-nitrile adhesives contain hazardous solvents, and also require use of organic solvents for cleanup. Moreover, known nitrile rubber adhesives have been found to be an inadequate adhesive agent to prevent twisting or otherwise ensuring dimensional and orientational parameters of an assembly are maintained while awaiting heat treatment of the assembly. These characteristics all contribute to nitrile rubber compounds being undesirable to ensure reliable, safe, convenient, permanent fixturing of desired dimensions for tube and baffle assemblies used in close-tolerance heat exchanger applications.
The inventors have found that thixotropic adhesives, when properly cured by the inventive methods herein, provide an unexpected yet measurably improved performance in permanent adhesive fixturing of tube and baffle bundle assemblies. For example, Henkel Loctite HYSOL® brand epoxy adhesive provided excellent flow, adhesion to copper and composite tubes and baffles, without expanding, sagging, or running HYSOL® is a registered trademark of Henkel Loctite Corporation, Rocky Hill, Conn. 06067 for proprietary adhesive formulations. In particular, HYSOL® Product 9432NA (hereinafter “Product 9432NA”) was selected for use in an example of the present invention because it is pumpable, requires no mixing, is non-sagging and paste-like, and exhibits high chemical and temperature resistance after heat curing, such as at oven temperatures below 400 degrees F., to result in the adhesive reaching a core temperature of at least 200 degrees F. Additionally, despite being specified for aluminum and steel, after heat curing, Product 9432NA was surprisingly found to have excellent tensile strength, adhesion, hardness, and shear strength when applied to non-etched copper tubes, copper nickel tubes, and stainless steel tubes, and also to metal, plastic, and composite baffles, and combinations thereof. In its uncured form, Product 9432NA is a proprietary epoxy adhesive having the following manufacturer's specification:
Upon application as previously described herein, thixotropic epoxy adhesives such as Product 9432NA envelope the tube 12, adhering it to the adjacent tube and well as to any adjacent baffle portion, forming a heat-curable composition that is ultimately durable, vibration resistant, and structurally sound. In most applications, the use of an adhesive bead 180 having a width of from about 1 mm to about 5 mm and a height of about 1 mm to about 2 mm is desirable to produce a cured and adhered tube and baffle bundle assembly that meets predetermined dimensional criteria, such as to fit within a housing having a corresponding internal size.
After curing by heat treatment, the adhered assembly as shown in
The invention further provides methods of reliably curing bundle assemblies after application of an adhesive 180 to the tubes 12 and baffles 25, 25′. The inventors have discovered that the curing of the adhesive 180 is a critical aspect of the durability of a finished bundle, both in-plant, in transit, and in use upon installation into a heat exchanger shell. While the selection of the adhesive 180 provides some information as to its curing requirements, there are many variables that arise upon application of the adhesive 180 to the tubes 12 and baffles 25, 25′ of a bundle assembly that make reliable curing a challenging problem. For example, the size of the adhesive bead, the amount and location of the adhesive within each assembly, the size of the assembly, the efficiency and configuration of the curing equipment, the configuration of the bundle assemblies and respective orientations of each, the surface condition of materials in the assemblies and the nature and thermal properties of the tube and baffle materials are all variables that affect the curing of adhesive applied within a bundle assembly. The inventors have developed methods of monitoring the curing of the adhesive, as well as methods of heat treatment that ensure complete curing for particular bundle assemblies.
For example, in the assembly previously described herein, adhesive Product 9432NA is used in combination with composite baffles and copper tubes, the adhesive bead having a width of from about 1 mm to about 5 mm and a height of about 1 mm to about 2 mm. In that example, heat curing of the bundle in an oven at less than 400 degrees F. for less than 5 hours resulted in a fully cured adhesive bond that can withstand vibration and movement in even the harshest shipping conditions, as well as in-use vibration and movement once placed in the shell of a heat exchanger.
Additionally, application of Product 9432NA or other thixotropic, minimally expending epoxies to tubes and baffles is novel because that adhesive is specified and known only for commercial use in surface to surface bonding of 2 substrates held in contact (such as by clamping) until curing at through the application of heat is accomplished.
While the invention has been described with reference to a preferred embodiment, 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 embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
This application claims priority to U.S. Provisional Patent Application Ser. No. 60/738,521 filed Nov. 21, 2005.
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| Number | Date | Country | |
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| 60738521 | Nov 2005 | US |
