US3799833A - Apparatus for jacketing fibrous ducts - Google Patents

Abstract

A method and apparatus for applying a jacket sheet to an open ended porous fibrous duct, by wrapping the sheet around the duct, applying end closures to the ends of the duct, at least on e such closure having a vacuum connection so that by reduction of pressure in the interior of the duct, the external atmospheric pressure will serve to hold the jacket sheet snugly against the duct, and inter-connecting the adjacent edges of the jacket sheet while it is being held snugly against the exterior of the duct under the influence of the reduced internal pressure and the external atmospheric pressure.

Description

March 26, 1974 0. WAKSMAN ETAL APPARATUS FOR JACKETING FIBROUS DUCTS 2 Sheets-Sheet 1 Original Filed Anril 1970 March 26, 1974 WAKSMAN ETAL APPARATUS FOR JAGKETING FIBROUS DUCTS 2 Sheets-Sheet 2 Original Filed April 1 1970 United States Patent 3,799,833 APPARATUS FOR JACKETING FIBROUS DUCTS David Waksman, Roeland Park, Kans., and James R. Stewart, Kansas City, Mo., assignors to Certain-Teed Products Corporation, Valley Forge, Pa.

Original application Apr. 14, 1970, Ser. No. 28,369, now Patent No. 3,668,039. Divided and this application Feb. 4, 1972, Ser. No. 223,791

- Int. Cl. B31f 7/00 US. Cl. 156-443 7 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for applying a jacket sheet to an open ended porous fibrous duct, by wrapping the sheet around the duct, applying end closures to the ends of the duct, at least one such closure having a vacuum connection so that by reduction of pressure in the interior of the duct, the external atmospheric pressure will serve to hold the jacket sheet snugly against the duct, and interconnecting the adjacent edges of the jacket sheet while it is being held snugly against the exterior of the duct under the influence of the reduced internal pressure and the external atmospheric pressure.

This is a division of application Ser. No. 28,369, filed Apr. 14, 1970, issued June 6, 1972 as Pat. No. 3,668,039.

This invention relates to the jacketing of fibrous ducts, and particularly to the application of a sheet type jacket to glass fiber ducts.

The invention has several general objectives, including the following:

First, the invention facilitates the jacketing operation and thereby increases the efliciency of production of jacketed ducts.

Another major objective is to provide a method and apparatus for improving the snugness of fit of a jacket upon the exterior surface of a porous fibrous duct.

It is a further object of the invention to provide for the use of jacketing material in sheet form, lengths of the sheet jacketing material being wrapped around the duct to be jacketed, with opposite edge portions positioned adjacent to each other. Moreover, the invention contemplates utilizing a vacuum system for reducing the pressure in the interior of the duct, and there-by provide for snugly holding the jacket sheet against the exterior surface of the duct during the jacket fastening or sealing operation.

Another object of the invention is to simplify the operation of sealing the adjacent edges of the jacket sheet.

The invention still further contemplates provision of equipment for the above purposes while providing adjustability so that the equipment is adaptable to the jacketing of ducts of various diameters or sizes.

How the foregoing objects and advantages are attained, together with others which will occur to those skilled in the art, will appear more fully from the following description referring to the accompanying drawings, in which:

FIG. 1 is a side elevational view of equipment according to the present invention, the equipment here being shown in use in the application of a jacket to a duct of one particular size;

FIG. 2 is an end view taken from the right of FIG. 1;

3,799,833 Patented Mar. 26, 1974 FIG. 3 is a view similar to FIG. 1 but illustrating the jacketing operation at a different stage than that shown in FIG. 1;

FIG. 4 is a transverse sectional view on an enlarged scale as compared with FIGS. 1 to 3, and illustrating still another stage in the jacketing operation;

FIG. 5 is a fragmentary view on the scale of FIG. 4, illustrating certain features of the jacketed duct; and

FIG. 6 is a view similar to FIG. 2 but illustrating adjustment of the equipment to provide for the handling and jacketing of a duct of larger size than the duct appearing in FIGS. 1 to 5.

Although the invention is applicable to the jacketing of porous ducts of various types, the invention is particularly useful in connection with the jacketing of glass fiber ducts used for various purposes such as in air conditioning, heating, and other air handling systems. Ducts of this type are commonly formed of glass fibers bonded together by a binder, for instance a synthetic resin binder. The wall of such ducts ordinarily is quite porous, so that without an impervious jacket, the duct would not well serve its purpose in air handling systems of the kind mentioned above. Moreover, the porosity of such ducts is a characteristic which is important in the carrying out of the method of the present invention.

Ducts of the general kind described above are of various sizes, ranging from about 3" to about 40" in outside diameter, and such ducts may have a wall thickness from about V2" up to about 3". In a typical duct of this sort, the wall is 1" in thickness and the duct has an inside diameter of 4" and an outside diameter of 6". Pieces or sections of 72" length are commonly employed, although the length may of course be varied for different purposes. The invention is also applicable to ducts of various specific end configurations, such as ducts adapted for butt joints at the ends or for shiplap joints at the ends. The ducts may also be of various cross sectional shapes, although cylindrical ducts are most common.

In the illustration of FIGS. 1 to 5 inclusive, there is shown the typical duct of 1" Wall thickness, 6" outside diameter. While such ducts are commonly of 72" length, the length as illustrated in FIGS. 1 to 5 would be of the order of 36".

The equipment in FIGS. 1 to 5 comprises a base or support 7 having an upright board or retaining element 8 at one end and a similar element 9 toward the other end, the element 8 in the embodiment shown being fixed and the element 9 being pivotally mounted upon the base or support 7 by means of the hinge indicated at 10, so that this element 9 may either occupy the upright position shown in full lines or the dot and dash position indicated at 9a.

In the embodiment of the apparatus illustrated, the elements 8 and 9 are adapted to serve as retaining means for closure plugs 11 and 12 which may be used if desired to aid in positioning and closing the opposite open ends of the duct indicated at D. The closure devices 11 and 12 may be formed in frustoconical shape, so that the inner ends of these devices may actually be inserted into the open ends of the duct.

A pair of adjustable platforms 13-13 are mounted upon the base by means of bolts 14. By loosening the bolts 14 and shifting the position of the platforms 13 toward or away from each other, as permitted by the slots 15 formed in the support 7, the inner edges of the platforms may be adjusted relative to each other in a manner providing a trough for receiving and positioning ducts of different sizes. While the jacketing material may be supplied from various sources, such as a roll, if desired a stack of jacket sheets of appropriate size may be mounted upon the platforms 13, as is indicated at S in the drawings. A stack of these sheets may be placed upon the platforms across the trough or channel between the inner edges of the platforms, and then the duct sections are sequentially mounted over the channel provided between the inner edges of the platforms and each such duct is wrapped with a jacket sheet S and the sheet is secured thereto in the manner to be explained.

In the sequence of operations performed in applying a jacket to a duct, with the form of equipment illustrated, after placement of the stack of jacket sheets in the position as indicated, and with the displaceable retaining board 9 swung downwardly to the position indicated at 9a, one end of a duct is then placed upon the closure device 11. Closure device 12 is then inserted into the other end of the duct and the displaceable board 9 is brought up to the full line position shown in FIG. 1, thereby serving to retain the duct and the closures 11 and 12 in assembled relation as illustrated. Advantageously a torsion spring is associated with the hinge 10 so that the spring normally urges the board 9 upwardly to its full line position, i.e., the position in which it serves to retain the closure plugs 11 and 12 in assembled relation with the duct. If desired, a releaseable latch may be provided for temporarily retaining the board 9 in the displaced position indicated at 9a.

Although the closure plug 12 may be mounted upon the board 9, such mounting is not necessary in the embodiment illustrated and, in fact, with a manual type of operation it is convenient to have the plug 12 separate from the board 9. At the opposite end of the duct, although the plug 11 may be arranged for separate handling, as with the plug 12, in the embodiment illustrated it is preferred that the plug 11 be mounted upon the upright retaining board 8. As one illustration of an arrangement used according to the invention, the plug 11 has a central passage therethrough in which a tube 16 is mounted, this tube projecting outwardly through an elongated slot 17 (see FIG. 2) formed in the board 8. The tube being threaded at its outer end and provided with a nut 18 so that the assembly of the tube and plug 11 may be fastened to the board 8. A flexible vacuum hose connection such as indicated at 19 is also associated with the tube 16, and with this arrangement it will be seen that a vacuum connection is provided to the interior of the duct, so that the pressure may be reduced therein.

After the duct is mounted in the manner described above and with the vacuum .system in operation, one of the jacket sheets S is flexed upwardly around the duct in the manner clearly shown in FIG. 4, with the opposite edges of the sheet overlapped in the zone at the top of the duct. Since the pressure is reduced on the interior of the duct, this tends to draw air inwardly through the porous duct wall into the interior, and this results in the external atmospheric pressure holding the jacket sheet snugly against the exterior surface of the duct. The holding action will continue until the desired sealing operation is performed. Various different techniques may be employed for interconnecting the adjacent edge portions of the jacket sheet. One preferred technique for this purpose is to provide jacket sheets of dimensions providing a slight overlap of opposite edge portions, and then interconnect the overlapped edge portions by an adhesive means. For this purpose an adhesive tape may be employed. A bracket 20 is desirably provided toward the top of the retaining board 8 in order to mount a supply spool 21 of adhesive tape, which may readily be drawn from the spool as indicated at T in FIG. 3 and applied to the lapped joint of the jacket sheet along the top of the duct.

After the adhesive tape is cut to an appropriate length, the seal may be completed by means of a hand tool carrying a pressure roller 22 (see FIG. 4) applying pressure over the tape along the joint. This hand tool may also incorporate a small warm air blower such as indicated diagrammatically at 23 in FIG. 4. The warmed air may.

also be relied upon for promoting the tight steal. A piece of jacketed duct prepared as just described is illustrated in FIG. 5, the jacket being partially broken away and the view also showing the adhesive tape T.

After a duct piece or section has been jacketed in the manner described above, the retaining board 9 may be displaced and the closure member 12 removed and the jacketed duct taken away and replaced by another duct to be jacketed.

When the plugs 11 and 12 are assembled with the duct and the vacuum system is in operation, the vacuum system itself will aid in maintaining the plugs and the duct in the desired positions. When a jacket sheet is wrapped around the duct, the pressure tending to draw the plugs into the open ends of the duct will of course be increased, but since the wall ofthe duct is porous, some air may enter into the ends of the duct wall and flow through the duct wall into the interior. This is desirable in order to avoid excessive decrease in pressure within the duct, such as might tend to cause the duct to collapse under the infiuence of the atmospheric pressure on the outside of the jacket sheet. For this same reason, it may be desirable with certain ducts to provide a jacket whose dimension lengthwise of the duct is slightly less than the length of the duct to thereby provide further leakage areas through the ends of the duct through which air may enter into the interior and thus avoid excessive increase in pressure within the duct.

The provision of some leakage area permitting flow of some air into the interior of the duct is also of importance in avoiding burning up or overloading of the vacuum or suction fan motor.

In order to accommodate a duct of large size as indicated at D1 in FIG. 6, the platforms 13 are preferably separated from each other and fastened in the positions indicated in full lines in FIG. 6, thereby providing a wider trough between the adjacent or inner edges of the plat forms. A stack of wider jacket sheets S1 are then placed upon the platforms and the larger ducts D1 sequentially brought to jacketing position in the manner described above.

For the handling of ducts of larger size, duct closure members of larger size may be used so as to effectively close the open ends of the larger duct. One such larger sized closure member 11a is indicated in FIG. 6, and it will here be seen that the central tube 16 which is associated with the vacuum connection 19 is now mounted at the upper end of the slot 17 in the retaining board 8, in order to bring the center of the closure plug 11a to the proper elevation above the platforms 13, as needed in the handling of the larger sized duct. It will be understood that at the opposite end of the duct, a closure plug corresponding to plug 12 shown in FIGS. 1 and 3 will also be used with the larger duct, and will be proportioned to fit the larger open end requiring closure. This latter plug or closure device will then be retained in its proper position in relation to the duct by means of the same displaceable or pivoted retainer board 9, as in the use of the equipment with the smaller duct as illustrated in FIGS. 1 to 4.

It will thus be seen that equipment of the type illustrated in the drawings is readily adaptable to the handling and jacketing of ducts of various sizes. Moreover, it should also be understood that the technique of the present invention may be achieved with modified forms of equipment, for instance the closure members 11 and 12 may be omitted and the planar surfaces of the end boards 8 and 9 may be brought directly against the end surfaces of a duct to be jacketed. The vacuum connection would of course still he made through at least one of the end boards, and even with the vacuum connection positioned at a given point, the equipment would still be readily usable with ducts of a wide range of sizes. In an arrangement in which the end boards are brought directly into contact with the end surfaces of the duct, the boards may be formed at least in part of rubber or other resilient material, for instance by applying a sponge rubber facing to the side of each board presented toward the duct.

If desired the equipment may also be proportioned so that more than one duct may be positioned in the equip ment in end-to-end relation, thereby providing for jacketing ducts in multiple, the same vacuum system being thereby concurrently used for simultaneous jacketing of more than one duct.

It will also be understood that insofar as the method is concerned, numerous other variations in equipment may be employed. In all cases, the vacuum system described above is of advantage in that the jacket sheets are held snugly to the exterior surface of the duct pieces under the influence of atmospheric pressure. This improves the fit of the jacket and avoids subsequent loosening or shifting of the jacket during installation or use.

Since the jacket sheet is held to the exterior surface of the duct being jacketed under the influence of the vacuum drawn within the interior of the duct, the system ordinarily prevents application of more than a single jacket sheet to any given duct being jacketed. There is no tendency in this system for the jacketing operation to retain more than one sheet in contact with a duct.

It will be understood that various phases of the operation as described above may readily be automated, but whether the various steps are carried out manually or automatically, the technique of the present invention greatly facilitates the application of jackets and greatly improves the snu-gness of the jacket and also the uniformity of application, from duct to duct.

The technique of the present invention may he used with jacketing materials or jacket sheets formed in a variety of ways, but preferably, the sheet material employed comprises a multiple layer laminate, for instance a foil-scrim-kraft paper laminate. The sheet material should have some appreciable flexibility, and in view of this, in a foil-scrirn-kraft paper laminate, these various layers would be quite thin, especially the foil layer. A typical jacket sheet of this type may have a total thickness of about 0.005". A heavy aluminum foil layer of sufiicient thickness to provide the desired structural strength would have greater rigidity than preferred in accordance with the present invention. The reason for this is that the system of the invention relies upon the pressure differential between the interior of the duct and the surrounding atmosphere in order to retain the jacket snugly in contact with the exterior surface of the duct, and the snngness of engagement is improved by using a sheet having substantial flexibility.

In a foil -scrim-kraft paper jacekting sheet, the scrim may comprise threads or filaments or natural fibers or of synthetic resins. Moreover, if desired the fibrous layer in the laminate may be composed of glass fibers, for instance in the form of a loose random glass fiber mat.

Still other forms of jacketing sheets may be employed, such as laminates made of aluminum foil, scrim or glass fibers and a layer of a heat sealable resin, such as polyvinyl chloride resin or vinylchloride-vinylidine copolymer resin. Moreover, a jacket may be utilized in which the laminate comprises a kratt paper layer, a fibrous layer and a resinous layer of the kind just referred to.

In addition to the desirable flexibility, the jacket sheet must of course possess the desired characteristic of impermeability, since the important function of the jacket is to contribute impermeability to the pervious or porous duct wall which is characteristic with ducts formed of fibrous material such as glass fibers.

The technique employed in interconnecting the edges of the jacket sheet which is wrapped around the duct will vary somewhat, depending upon the character of the sheet itself. In general, the application of an adhesive tape may be employed with virtually any appropriate jacket sheet. However, where a heat sealable layer is embodied in the jacket sheet material, the sealing may be effected by bringing the layers of heat sealable resin of the opposite edge portions of the jacket together along the line of junction and then applying pressure and heat to efiect a seal, even without the use of a separate adhesive tape. In all instances, however, the vacuum system is of advantage in establishing the snug jacket fit and also in holding the jacket sheet in position during the sealing operation.

Although vacuum connections may be provided at both ends of the duct being jacketed, this is ordinarily not needed and the use of a vacuum connection at only one end, as shown in the illustrative embodiment of the drawings is of advantage from the standpoint of simplicity.

We claim:

1. Apparatus for applying a jacket sheet to an open ended porous fibrous duct, comprising a support for a flexible jacket sheet, means for mounting a duct over the jacket sheet on the support in position so that opposite edges of the jacket sheet may be flexed upwardly around the duct with opposite edges adjacent each other and thus enclose the duct, the mounting means comprising a pair of closure devices adapted to engage and close opposite open ends of the duct being jacketed, one of said closure devices having a vacuum connection providing for reducing the pressure in the interior of a duct being jacketed, and means for retaining the closure devices in engagement with opposite ends of the duct, the retaining means for the closure device at one end of the duct being displaceably mounted to provide for disengagement of the closure device from the end of the duct.

2. Apparatus as defined in claim 1 in which the displaceably mounted retaining means is disposed at the end of the duct opposite to the end engaged by the closure device having the vacuum passage.

3. Apparatus as defined in claim 1 in which the means for mounting the duct comprises plugs adapted to fit into the ends of the duct and being adjustable to different heights above the support for the jacket sheet to provide for accommodation of ducts of different sizes and for positioning the ducts close to the jacket sheet on the support.

4. Apparatus as defined in claim 1 in which the means for mounting the duct comprises planar closure devices adapted to engage the end surfaces of the duct.

5. Apparatus as defined in claim 1 and further including means for mounting a supply of jacket sealing tape in position to deliver tape along the line of junction of the opposite edges of the jacket sheet.

6. Apparatus for applying a jacket sheet to an open ended porous fibrous duct, comprising a support for a flexible jacket sheet, means for mounting a duct to be wrapped in a jacket comprising a pair of closure devices adapted to engage and close opposite open ends of the duct being jacketed, one of said closure devices having a vacuum connection providing for reducing the pressure in the interior of a duct being jacketed, and means for retaining the closure devices in engagement with opposite ends of the duct, the retaining means for the closure device at one end of the duct being displaceably mounted to provide for disengagement of the closure device from the end of the duct.

7. Apparatus for applying a jacket sheet to an open ended porous fibrous duct, comprising a support for a flexible jacket sheet, and means for mounting a duct over the jacket sheet on the support in position so that opposite edges of the jacket sheet may be flexed upwardly around the duct with opposite edges adjacent each other and thus enclose the duct, the mounting means comprising a pair of closure plug devices adapted to be inserted into and close opposite open ends of the duct being jacketed, one of said closure devices having a vacuum passage there- 7 8 through providing for pneumatically holding a jacket sheet 2,776,098 1/ 1957 Baumann et a1. 242129.5 1 in engagement with the exterior of the duct. 3,124,497 3/1964 Sydanmaa 15 6215 References Cited ALFRED L. LEAVITI, Primary Examiner UNITED STATES PATENTS 5 D. A. SIMMONS, Assistant Examiner 2,191,406 2/ 1940 Mandel 156-564 3,455,758 7/1969 Straughan 156-218 X 2,651,479 9/1953 Bauer 242129.51 156-215, 218, 285, 475, 564, 573

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