US 3351348 A
Description (OCR text may contain errors)
Nov. 7, 1967 c. F. DUPUIS VACUUM CHAMBER SEAL Filed Jan. 29, 1965 9 3 n0 1.. 1 @7 m o f/ 6c W mm vi. W I 7:? 7/ ww 1 3 7. a m a m INVENTOR C D F. DUPU is ATTORNEYS W... Wham...
ABSTRAET 015 THE DECLOSURE The invention relates to means for sealing a vacuumtreating chamber and comprises a flexible lo'wer fight of an endless belt which overlies and engages the chamber wall portion defining a work-admitting opening and is sealingly responsive to environmental pressure differential.
Background and summary of the invention This invention relates to a novel apparatus for sealing an opening in a partition between a plurality of chambers under a fluid pressure differential while simultaneously feeding a web of material through the opening and yet substantially preventing fluid leakage between the plurality of chambers.
It is conventional to apply a metallic coating such as aluminum, tin or silver to a Web or strip of material, such as plastic, paper or other fibrous materials by transporting the web or strip through a metallic vapor atmosphere in a vacuum chamber. Under the reduced pressure of the vacuum chamber coating materials are transformed into a metallic vapor in a conventional manner and are coated upon the strip or web of material by condensation.
Since this operation takes place at a reduced pressure within the vacuum chamber, it is thus necessary and desirable to maintain an emcient seal between the web or strip as it enters an opening in one end of the chamber and is removed through an opening, generally at an opposite end of the chamber. Various types of mechanical and pneumatic seal constructions have been utilized in the past for sealing the entrance and exit openings in such vacuum chambers, however, all such seals have proved vastly inadequate for high speed, low cost vapor metallization of web material. One such conventional seal construction is a pair of resilient strips secured adjacent the openings in the vacuum chamber. These resilient strips bear against upper and lower surfaces of the strip material in the vacuum chamber. These resilient members are clamped to the strip material, a vacuum is drawn in the chamber, and a suitable length of the strip material is then coated. Thereafter, the resilient sealing members are released and another length of the strip material is fed into the vacuum chamber, and the process is repeated. This, of course, is a highly time-consuming inefficient method of coating strip material. In addition, the resilient sealing members become worn in a relatively sort period of time because of the abrasive nature of the strip material, and must be periodically replaced.
In other conventional vacuum metallizing chambers the chambers are divided by a plurality of partitions to form individual chambers within the vacuum chamber. Each of these partitions has an opening through which the sheet material is transported, and these openings must similarly be sealed to maintain a pressure difiierential between the plurality of individual chambers. Resilient sealing strips of the type above described for sealing adjacent the openings in such partitions to maintain a pressure differential between the individual chambers. These sealing devices, however, are again relatively inefiicient and constant replacement thereof is generally necessary.
It is an object of this invention to provide a novel seal 3,35il,4t8 Patented Nov. 7, i967 structure which overcomes the deficiencies inherent in the prior art seal constructions noted above, and in particular, to provide a novel sealing structure which is equally adapted for use at the entrance and exit ends of a vacuum metallization chamber (as Well as the partitions in the chamber), has a relatively long wear-life, substantially prevents leakage between adjacent chambers, and is highly efiicient, both from an operating-cost and replacementcost standpoint.
A further object of this invention is to provide a novel seal structure for sealing an opening in a parition separating a first chamber from a second chamber, the opening in the parition establishing access between the first and second chambers, the seal structure including sealing means overlaying the opening in the partition, and the sealing means including a movable sealing web intimately contacting the partition adjacent the opening under the influence of a pressure differential between the first and second chamber.
Still another object of this invention is to provide a novel seal structure of the type immediately above described in which the sealing web is endless and is trained about a roller journaled at each side of the opening in the partition.
Another object of this invention is to provide a novel means for transporting a web or strip of material through an opening in a partition establishing access between two areas under a pressure differential by first creating a pressure differential between the two areas, transporting the web of material through the opening, and maintaining the pressure differential by covering the opening and the Web adjacent the opening from the high side of the pressure differential with a movable flexible seal.
With the above and other objects in view that will here inafter appear, the nature of the invention will be more clearly understood by a reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.
In the drawings:
FIGURE 1 is a fragmentary vertical sectional view with parts shown schematically, and illustrating a novel seal structure of this invention mounted adjacent an opening in a partition between two chambers under a pressure differential.
FIGURE 2 is an enlarged fragmentary vertical section al view of the seal structure of FIGURE 1 and more clearly illustrated the effect of the pressure differential between the chambers and a flexible, movable web of the seal structure.
Description of the preferred embodiment A vacuum metallization chamber 5 is shown in FIG- URE 1 of the drawings, and includes an entrance end wall or partition 6. The vacuum metallization chamber 5 is substantially identical to the conventional vacuum chambers heretofore described and includes an exit end wall or partition (not shown) as well as a plurality of intermediate partitions (also not shown) dividing the vacuum metallization chamber 5 into a plurality of individual chambers or compartments.
The vacuum metallization chamber 5 is maintained at a pressure below atmospheric pressure by a source of vacuum 7 communicating through a conduit 8 and the partition 6 with the interior of the chamber 5. The source of vacuum may, for example, be a conventional vacuum pump.
The partition 6 is disposed substantially vertically but includes a central angularly offset portion 10. A narrow, substantially rectangular opening or slit 11 is formed in the portion 10 of the partition 6. The opening 11 is set olf by an upper surface 12 in spaced opposing relationship to a lower surface 13, and a side surface 14 in spaced, parallel opposing relationship to an identical side surface (not shown). The lower surface 13 partially defining the opening 11 has a gradually rounded portion 15 which blends into a planar exterior surface 16 of the partition 6.
A sealing box or sealing chamber 17 is integrally joined to the entrance wall or partition 6 of the vacuum chamber 5. The sealing box 17 includes a substantially square housing 18 having a top wall 20 and an entrance wall or partition 21. A conventional squeeze roller assembly 22 is journaled in an opening (unnumbered) in the entrance wall 21 of the housing 20. The sealing roller assembly 22 is entirely conventional and a pair of rollers 23 thereof cooper-ate in a known manner to maintain the sealing box 17 in a gas-tight condition.
A source of pressurized insert gas 24, such as argon, helium, xenon, etc., is placed in fluid communication with the interior of the sealing box 17 by a fluid conduit 25 passed through the top wall 20 of the housing 18. Any conventional compressor capable of placing the inner gas in the interior of the housing 18 under a pressure of up to 80 microns of mercury may form the pressurized inert gas source 24. The pressurized insert gas within the housing 18 performs a dual function which will be more fully described hereafter.
A seal structure or sealing means (see FIGURE 2) is positioned in the interior of the housing 20 of the sealing box 17 adjacent the central angularly offset portion 10 of the partition 6. The sealing means or seal structure 30 comprises a first roller 31 and a second roller 32. The rollers 31 and 32 are preferably constructed from steel and has an axial length substantially greater than the transverse width of the opening 11 measured between the opposed parallel side wall 14 thereof.
The first roller 31 has a shaft 33 which is journaled in a conventional manner in the housing 18 above the upper surface 12 of the opening 11 adjacent the planar exterior surface 16 of the partition 6. The second roller 32 similarly includes a shaft 34 journaled in a conventional manner to the housing 18 adjacent the planar exterior surface 16 of the partition 6 below the lower surface 13 of the opening 11. Either one or both of the rollers 31 and 32 is rotated by a drive mechanism (not shown), such as a conventional motor.
A sealing web 35 is entrained about the rollers 31 h and 32. The sealing web 35 includes a first run 36 completely overlaying the opening 11 in the partition 6. The first run 36 is normally parallel and slightly spaced from the planar exterior surface 16 of the partition 6. However, because of the pressure differential between the sealing box 17 and the vacuum metallization chamber 5, the inert pressurized gas within the sealing box 17 urges the first run 36 of the sealing web 35 into intimate contact with the partition 6 adjacent the opening 11. The second run 37 of the sealing web 35 is in spaced parallel relationship to the first run 36 ofthe sealing web 35 and the planar exterior surface 16 of the partition 6.
The sealing web 35 is preferably constructed from a relatively flexible material, such as plastic, rubber, canvas, or metal, and is preferably relatively impermeable.
The operation of the sealing means 30 will be best understood by referring to FIGURE 1 of the drawing which illustrates an upper web 38 and a lower web 39 being transported from a pair of identical reels 40, 40 in overlying face-to-face relationship into the sealing box 17. The webs 38 and 39 are fed between the rollers 33, 33 of the squeeze roller assembly 22 and are guided between the lower run 36 of the sealing web 35 and the planar exterior surface 16 of the partition 6 inwardly through the opening 11 into the vacuum metallization chamber 5. The webs 38 and 39 are preferably transported through the sealing box 17 and the vacuum chamber 5 at a speed subtantially equal to the speed of the driven sealing web 35. The transverse width of the sealing web 35. The transverse width of the sealing web 35 is greater than the transverse width of the superimposed webs 38 and 39. Therefore, as the superimposed webs 38 and 39 are transported between the first run 36 of the sealing web 35 and the exterior surface 16 of the partition 6, the transversely projecting edge portions of the first run 36 are urged into intimate contact with the exterior surface 16 by the pressurized gas within the sealing box 17. Above the upper surface 12 of the opening 11 the entire run 36 of the sealing web 35 is urged into intimate contact with the exterior surface 16 of the partition 6. Thus, the first run 36 of the sealing web 35 at all times is urged into intimate contact with the planar exterior surface 16 of the partition 6 by the pressurized gas within the housing 18 of the sealing box 17.
After the superimposed webs 38 and 39 have passed through the opening 11 and the partition 6 they are conveyed in a conventional manner through the vacuum metallization chamber 5. During the movement of the webs 38 and 39 through the chamber 5, a metallic coating is condensed upon the surfaces of these webs in a conventional manner, after which, the webs are removed through an exit wall or partition (not shown) of the vacuum chamber 5. A sealing structure identical to the sealing structure 30 may be mounted at the exit wall or partition of the vacuum chamber 5 in a manner substantially identical to that heretofore described, and additional sealing structures can be positioned adjacent partitions within the vacuum chamber 5.
it should be particularly noted that the sealing structure 39 not only prevents the escape of gas from the housing 18 into the chamber 5, but also, various benefits are attained by this structure. For example, the angular offset relationship of the central portion 10 of the partition 6 prevents abrupt or radical bending of the superimposed webs 38 and 39 after they are transported through the opening 11 in the partition 6. Undesirable wear of the sealing web 35 is reduced because the sealing web 35 is traveling at substantially the same speed as the webs 38 and 39, and very little frictional rubbing Contact occurs between the sealing web 35 and adjacent structures. While a pair of webs 38 and 39 have been illustrated being passed between the first run 36 of the sealing web 35 and the exterior surface 16 of the partition 6, it should be particularly noted that a single web or more than a pair of Webs can be similarly transported through the opening 11 without a change in the pressure differential between the sealing box or chamber 17 and the vacuum chamber 5. In the illustrated embodiment of this invention the run 36 is normally spaced from the exterior surface 16 a distance substantially equal to the thickness of the webs 38 and 39. However, if either of these webs were removed and a single web were to be transported through the opening 11, no change in the sealing structure 31) is required. That is, the fluid pressure within the sealing box 17 would still urge the first run 36 o" the sealing web 35 into intimate engagement with the planar exterior surface of the partition 6.
As has been heretofore pointed out, the pressurized inert gas within the sealing box 17 performs two functions. A first and most important of these is to urge the first run 36 of the sealing web 35 into intimate, overlaying contact with the exterior surface 16 of the partition 6. Additionally, the inert gas promotes bright metallization and vacuum pressures as high as microns of mercury within the vacuum metallization chamber 5. In conventional metallic-vacuum coating of web or strip material, the deposition of brilliant evaporated metal in a high vacuum ceases when the ambient gas pressure rises above seven microns of mercury. The presence of the inert gas, such as argon or helium, in the sealing box 17 promotes bright metallization up to a vacuum of 80 microns of mercury within the vacuum chamber 5 because of the extremely slight escape or leakage of this inert gas from the sealing box 17 through the opening 11 into the vacuum chamber 5.
From the foregoing, it will be seen that novel and advantageous provision has been made for carrying out the desired end. However, attention is directed to the fact that variations may be made in the example device disclosed herein Without departing from the spirit and scope of the invention as defined in the appended claims.
1. A seal structure comprising a plurality of chambers, a partition separating a first of said chambers from a second of said chambers, an opening in said partition establishing access between said first and second chambers, means for supplying fluid under pressure into said first chamber, mean for exhausting fluid from said second chamber and sealing means for closing the opening in said partition whereby said first and second chambers are maintained under a pressure di'lferential, said sealing means including an endless sealing Web entrained about a pair of rollers journalled in said first chamber at opposite sides of said opening, said endless sealing web including first and second sealing runs, and said first sealing run being parallel to said partition and in overlying relationship to said opening whereby the pressure differential between said chambers urges said first sealing run into intimate contact with said partition, means for feeding a Web of sheet material toward said sealing means along a predetermined linear path, and said partition is disposed at an angle other than normal to said predetermined linear path whereby said sheet material web is fed through said opening without abrupt angular changes in the configuration thereof.
2. The seal structure as defined in claim 1 wherein said opening is disposed at an angle other than normal to a plane taken through said partition,
References Cited UNITED STATES PATENTS 890,252 6/1908 Thompson. 1,371,914 3/1921 Lewis et a1. 34242 X 1,632,760 6/1927 Jones 34242 X 2,298,906 10/1942 Sperry 34242 X 2,299,145 10/ 1942 Hill et a1. 34242 X 2,890,878 6/1959 Steinhertz et a1. 34242 X 2,986,911 6/1961 Jackson 34242 X 3,011,266 12/1961 Fleissner 34242 X 3,158,507 11/1964 Alexander 34242 X 3,170,576 2/1965 Frank 214--17.4
MORRIS KAPLAN, Primary Examiner.