US2912013A

US2912013A - Duct construction

Info

Publication number: US2912013A
Application number: US573458A
Authority: US
Inventors: Helmut A Freyholdt; Fred M Mccown
Original assignee: IND PARK CORP
Current assignee: IND PARK CORP; INDUSTRIAL PARK Corp
Priority date: 1956-03-23
Filing date: 1956-03-23
Publication date: 1959-11-10
Anticipated expiration: 1976-11-10

Description

NOV- 10, 1959 H. A. FREYHOLDT ETAL A2,912,013

DUCT CONSTRUCTION 2 Sheets-Sheet 1 Filed March 23. 1956 VIA WllIlIIIlIIIIlI/A arent Gtlice 2,912,013 Patented Nov. 10,` 1959` DUCT CONSTRUCTION Helmut A. Freyholdt, Santa Monica, and Fred McCown, West Covina, Calif., assignors to industrial Park Corporation, a corporation of California Application March 23, 1956, Serial No. 573,458

2 Claims. (Cl. 13S-75) This invention pertains to improvements in the construction of sheet-metal ducts, such ducts being commonly used in heating and Ventilating systems and wherever it is desired to restrain and convey heating or cooling air, exhaust gas or the like. The invention also pertains to locking devices for use in the construction of sheet metal ducts and the like, said locking devices facilitating the assembly and construction of the ducts Without the necessity of riveting, bolting or crimping of the metal. The constructions herein disclosed permit shipment of ducts and duct elements in substantially ilat form and expedite the assembly of such elements into a complete duct on the job.

The manufacture and installation of ducts presents ntunerous problems. Duets employed for conducting various gases must be made of metal, should be relatively light, gas-tight and easily installed. Ordinarily galvanized` or tinned sheet metal ranging from 26 to about 30 gauge is preferred but these heavier sheets are ditcult to form and connect along longitudinal edges in making a duct of a desired rectangular cross section. Rather high quality stock is normally used, the stock being of very low Weight or gauge, say 16 or even 18 gauge, in order to permit the longitudinal edges to be bent and crimped together to make what is known as a Pittsburgh seam, double seam, grooved seam, standing seam, or other methods of connecting adjacent sections or panels to each y other. Since these various prior types of seams or joints require that the metal be bent very sharply, the protective coating or galvanizing often cracks or peels, subjecting the duct to attack by constituents of the gases, moisture, etc. or locks have precluded the use of less expensive metallic sheets and often necessitated the use of alloys, aluminum and other much more expensive materials. In addition, the formation of those locks or seams was timeconsuming, and required the use `of special tools and trained personnel on the job. vSince ducts are relatively light in weight but bulky, the shipment of pre-fabricated ducts was expensive. The present invention relates to improvements and novel methods of construction whereby sheet metal ducts may be manufactured from relatively malleable, less expensive sheet metal stock which need not have the block forming qualities required heretofore. Moreover, the construction described hereinafter permits panels from which a duct is to be constructed These prior methods of forming seams The lockingpstrips frictionally and vpositively grasp and hold marginal edge areas .and adjacent sheets'- Without necessitating bending, stress or forming of the metal along the edge. Asa' result Ventilating ducts and the like may be quickly and readily assembled without the use of special tools.

It is an object of the present invention therefore to disclose and provide a novel sheet metal duct construction.

A further object of the invention is to disclose and provide locking devices capable of being embodied in or used in connection with sheet metal panels for the construction of ducts or wherever sheet metal panels need be connected.

A still further object of the invention is to disclose and provide sheet metal duct constructions whereby relatively light gauge, inexpensive, flat stock may be used, such fiat stock having characteristics of strength and rigidity equal to that of much heavier stock. f

These and various other uses, advantages and adaptations of the invention will become apparent from the following description, reference being had to the appended drawings in which certain exemplary forms are illustrated. p

In the drawings:

Fig. 1 is a perspective view of a duct made in accordance with the present invention;

Fig. 2 is an enlarged section taken through a corner of the duct illustrated in Fig. 1, the section being taken along the plane II--Ilg Fig. 3 is an enlarged view of an end portion of a corner locking strip;

Fig. 4 is an end view of a sheet of metal provided with integral locking devices along itsY longitudinal edges;

Fig. 5 is an enlarged section of an end locking strip of the character illustrated in Fig. 1; f-

Fig. 6 is an enlarged view showing the end locking strip before assembly and tightening; and

Fig. 7 is a section through a part of a reducing frame which may be employed in reducing the cross sectional area of a duct. l

Although, as previously indicated, the constructions hereinafter disclosed are capable of being used in the construction of many devices and pieces of equipment, such as drying ovens, annealing ovens, spray booths and whateversheet metal construction is indicated, the advantages of the construction are emphasized in heating and Ventilating ducts of the character illustrated in Fig. l'. As there shown the completed duct is formed from upper and lower panels 1 and 2 and

side panels

3 and 4 connected together at the corners by means of locking devices including backing members such as the member to be shipped in a substantially flat form, these substanj F v sheet.

Generally stated, the present invention is directed to a novel locking strip capable of being used at corners of a duct or in connecting panels lying in a common plane.

10. Fig. 1 illustrates an end of a duct and it will be noted that a continuation of the side wall in which panel 4 is positioned'comprises another side wall panel 5 which is connected to the end of panel l by means of a locking strip 40. Attention is further called to the fact that the longitudinal edges of these

side panels

3 and 4 are straight rectilinear edges Without folds or bends and the sarrie comments apply to the top and bottom panels 1 an 2.

The construction of the backing member 10 will be evident from Figs. 2 and 3. As there shown the locking means comprises the backing member and a locking strip generally indicated at l2, these two elements being connected together by a series of spaced rivets 13.

The backing member 10 may be said to include an anchor portion 14 and a longitudinally extending resist portion on each side thereof and integral therewith, the

resist portions

15 and 16 lying in planes inclined to the plane of the anchor portion 14.

The elongated locking strip 12 is of the same length as the backing member and is provided with a back portion 17 lying in a plane substantially parallel to the anchor portion 14, and with longitudinally extending marginal grasping portions 18 and V1 8' bent toward each other with the plane of the back portion 17 and the planes of the

grasping portions

18 and 18 assuming the coniiguration of the longitudinal faces of'atrilateral prism so as to present grasping faces 19 and 19', respectively, toward the opposing resist portions and 16, respectively. A longitudinal edge of the top panel 1 is inserted between the resist portion 16 and the grasping portion 18' and is firmly held therebetween. Similarly, a longitudinal edge of the side wall panel 3 is inserted between the resist 15 and the grasping portion 18 and is frictionally and rmly held therein. It may be noted that inasmuch as the grasping portions 18 are bent out of the back 17 a rounded corner is presented to the incoming edge of a panel to be held and locked by the locking means 10, this rounded corner facilitating insertion and guiding the edge of a panel such as the panel 3.

It hasbeen discovered that a locking means of the character Ydescribed holds and positions panels of a duct with remarkable tenacity and materially enhances the strength and rigidity of the completed duct. Frictional engagement between the grasping portions and the resist portions is partly due to the prestressed construction employed, this prestressed construction being made more evident from a contemplation of Fig. 3. Fig. 3 illustrates in perspective an end portion of a locking means before it receives adjacent longitudinal edges 'of panels converging at a corner. In Fig. 3 a true 90 angle is indicated by the dash lines 20. It will be noted that the

resist portions

15 and 16 of the elongated backing member 10 have been formed or bent so as to include an angle of slightly less than 90. Similarly, the

grasping portions

18 and 18 of the locking strip 12 'have been bent inwardly toward each other so as to make an included angle of less than 90 but more than 45 with the back 17 of the locking strip. When the backing member 10 and the locking strip are connected together by the series of rivets or the like 13 (such rivets preferably passing through the anchor portion of the backing member and the back of the locking strip) the outwardly directed grasping faces of the

grasping portions

18 and 18 are yieldably urged against the opposing surfaces of the

resist portions

15 and 16 and the intersections of the planes of the back portion 17 and the planes of the grasping

portions

18 and 18 dene axes about which the respective grasping portions are resiliently deflected. It may be noted that the opposing edges 19" of the grasping portions are spaced from each other a distance greater than the diameter of the rivet 13, when the locking strip is assembled but has not received or joined wall panels. Upon insertion of the wall panelsl 1 and 3 as illustrated in Figs. l and 2, these longitudinal edges 19" virtually abut the shanks of the rivets 13. The resiliency of all of the metal employed in the locking strip 12 is therefore utilized in pressing the grasping portions against the edge areas of panels 1 and 3. These edge areas may be inserted with relative ease under the urging of a few light blows of a hammer but can only be removed with a great deal of diiculty after they have once been inserted into the locking means.

At this time attention is called to a method of treating the wall panels so as to permit relatively light-weight or small gauge sheet metal to be used without loss of strength or rigidity. For purposes of facilitating description and simplifying the drawings, only panel 1 has been shown so treated. By referringto Figs. 1 and 2, it will be noticed that panel 1 is provided with two sets of elongated but interrupted indentations (and resulting bosses). The metal has been deformed to form one set of substantially parallel indentations, such indentations being indicated at 21, 22, 23 and 24, and another set of indentations extending in lines at right angles to the lines of the first set of indentations, such secondary -indentaparts before any panels are inserted.

tions being indicated at 25, 26, 27I and 28. Each set of indentations is interrupted by the other set, it being noted that

indentations

23 and 24 are interrupted by indentation 25, and indentation 25 is spaced from all of its adjacent indentations by undeformed metal. Indentation 25 is interrupted from indentation 26 by another indentation running at right angles thereto, etc. It may also be noted that these indentations all stop short of the longitudinal and transverse edges of the panel 1, leaving such edges in their original planar condition so as to present smooth marginal edge areas adapted for insertion into suitable locking means.

It has been found that the use of two sets of mutually interrupted elongated identations, each set extending in a direction substantially transverse to the direction of the other set, permits the use of a light-weight metal, say 20 gauge, with an apparent stiffness, rigidity and strength normally obtained by the use of 26 and 28 gauge metal. Since these indentations have a maximum depth of not over about four times the actual thickness of the metal, they do not present a surface which interferes with the smooth flow of air or gases thereover. This method of construction saves approximately one-half the weight.

The locking means of the present invention need not take the form of separate locking strips and backing members as illustrated in Fig. 3 but may be made an integral part of a sheet. This method of utilizing the present invention is illustrated in Fig. 4 and as there shown the sheet or panel 2 is provided with an integral locking means along each longitudinal edge for frictionally receiving and holding the edge areas of

side panels

3 and 4. It will be noted that the longitudinal edge of panel 2 has been bent to form an anchor portion 34 and an upstanding resist portion 35. Held within the included angle is the locking strip 32 provided with its grasping

portions

38 and 38 bent toward each other so as to present a grasping face opposing the resist 35. The locking strip is attached to the anchor portion of the backing element or panel by means of spaced rivets or the like 33. A similar construction is used at the other longitudinal edge of the panel 2. It will be evident that all of the material necessary to form a completed duct can therefore be sent in the form of top and bottom panels made in accordance with Fig. 4 and side panels made of simple sheets of metal having straight rectilinear undeformed edges. Shipment in its knocked down form occupies but little space and the entire duct can be readily assembled on the top or bottom panels without the use of special tools.

Locking means such as 40, used for connecting abutting ends of panels lying in the same plane, are illustrated in Figs. 5 and 6. Fig. 5 is a transverse section illustrating this type of locking means connecting

panels

4 and 5. It will be noted that in such locking means the backing member 41 is substantially identical to the locking strip 42. The backing member includes an anchor portion 44, longitudinal edge areas being bent to form the resist

portions

45 and 46. The locking strip 42 comprises a back 47 lying in a plane substantially parallel to the plane of the anchor portion 44, longitudinal edge areas of this back 47 being bent to form the grasping portions 48 and 48', the grasping portions presenting grasping faces 49 directed toward the resist and adapted for frictionally holding the edge area of a panel inserted between the grasping portion and the opposing resist. The backing member and the locking strip are connected together by means of small bolts 43 passing through the anchor portion and back of the backing member and locking strip, respectively.

As indicated in Fig. 6, resiliency of the formed elements is again employed in generating a high frictional grasp upon the edge areas of panels. The right hand portion of Fig. 6 illustrates the arrangement of the formed It will be noted that the inner edge 49 of the grasping

portions

46 and 48 is spaced from the stud or bolt 43. The left hand portion of Fig. 6 illustrates the position of the parts after a panel has been inserted. After such panel has been inserted the nut on the bolt 43 is tightened, bringing the grasping portions into tirmer contact with the edge areas of the panel, the ultimate position assumed by the parts being illustrated in Fig. 5, wherein the grasping faces 49 are in face-to-face engagement with edge areas of

panels

4 and 5. Although it has been found desirable to provide the locking means 40 with adjustable bolts, this is not necessarily true in all cases since the device may be employed with an unadjustable connecting means such as a rivet, the grasping faces exerting yieldable pressure against their opposing resists at all times.

Fig. 7 illustrates the utilization of the locks hereinbefore described in combination with a frame which can be employed for increasing or reducing the cross sectional size of a duct. As there shown, the frame 50, of desired rectangular plan, is provided with an external wall 51 and an internal wall 52, the internal wall 52 being preferably narrower than the external wall. The two walls are connected with a tapering wall portion 53 and an end wall 54, thereby performing a hollow frame. The walls 51 and `52 now act as resist elements or backing members. Locking strips such as the locking strip 42 is now carried by the external wall 51 and a similar locking strip 42" is carried by the internal wall 52. These locking strips 42' and 42 are substantially identical to the locking strip 42 described hereinbefore in connection with Fig. 5. The two locking strips 42' and 4 are connected together and to the backing frame 50 by means of a bolt, rivet o-r the like 43. It will be evident that this frame may be readily connected to the end of a duct having wall panel 55, end areas of this panel cooperating with locking strips 42 and the frame then connected to an additional duct of smaller cross sectional area having wall panels 56, end areas of such panels being grasped by locking strips 42". The tapering or inclined end wall 53 minimizes turbulence.

Ducts for various purposes and numerous types of equipment can be manufactured by the use of one or more aspects of the above invention. All changes and modifications coming within the scope of the claims are embraced thereby.

We claim:

1. A sheet metal duct construction element comprising: a sheet of metal, each longitudinal edge portion being provided with a locking means for frictionally receiving and holding edge areas of another sheet of metal to form the corner of a duct, each of said locking means comprising a longitudinally extending marginal edge area of the sheet bent to form a resist port-ion lying in a plane virtually transverse to said sheet and an anchor portion `separating the resist portion from the rest of the sheet,

a locking strip provided with a back portion lying in a plane substantially parallel to the anchor portion and longitudinally extending marginal grasping portions bent toward each other and toward the anchor portion; and means connecting said anchor portion and back portion to hold said locking strip with one of said marginal grasping portions presenting a grasping face in resilient contact with the resist portion in position to permit insertion of the edge of said another sheet of metal therebetween and with the plane of the back portion and the planes of the grasping portions assuming the configuration of the longitudinal faces of a trilateral prism and with the intersections of the planes of the grasping portions and the plane of the back portion defining the axes about which the respective grasping portions are resiliently deflected.

2. A lockingy and connecting device for sheet metal ducts and the like comprising: an elongated backing member of resilient strip metal including an anchor portion and a longitudinal resist portion on each side thereof and integral therewith, said resist portions lying in planes inclined to the plane of the anchor portion, the angle included between said resist portions being slightly less than an elongated locking strip provided with a medial back portion lying in a plane substantially parallel to the anchor portion of the backing member and with longitudinally extending marginal grasping portions bent toward each other, each of said marginal grasping portions lying in a plane which includes an angle of less than 90 with said back portion; said locking strip being nested within said backing member with said back portion in spaced relation to the anchor portion and with the planes of the back portion and the planes of the grasping portions assuming the configuration of the longitudinal faces of a trilateral prismk and with the intersection of the planes of the grasping portions and the plane of the back portion defining the axes about which the respective grasping portions are resiliently deflected; and means connecting the anchor portion and back portion.

References Cited in the le of this patent UNITED STATES PATENTS 1,045,740 Phillips Nov. 26, 1912 1,067,189 Murphy et al. July 8, 1913 1,199,357 Evans Sept. 26, 1916 1,278,343 Hester Sept. 10, 1918 1,351,613 Brown Aug. 31, 1920 1,425,953 Figarsky Aug. 15, 1922 1,603,627 Montgomery Oct. 19, 1926 2,105,784 Hagberg Jan. 18, 1938 2,126,499 Petersen Aug. 9, 1938 2,381,178 Munyon Aug. 7, 1945 2,498,753 Deitsch Feb. 28, 1950 FOREIGN PATENTS 605,534 Great Britainv July 26, 1948