US3680795A

US3680795A - Vapor knife

Info

Publication number: US3680795A
Application number: US62550A
Authority: US
Inventors: Raymond F Galitz
Original assignee: Continental Can Co Inc
Current assignee: Continental Can Co Inc
Priority date: 1970-08-10
Filing date: 1970-08-10
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01

Abstract

This disclosure relates to a vapor knife for directing emission of a vapor stream. The vapor knife includes a hollow tubular member defining an interior cavity and having an elongated axially extending vapor emission opening which is in communication with the cavity and the exterior of the tubular member. The vapor knife directs a wide jet of vapor against a printed or coated article to effect the treatment of the article with the vapor.

Description

United States Patent I Galitz [451 Aug. 1, 1972 [54] VAPOR KNIFE 2,624,625 1/1953 Magos et a1 ..239/587 X 2,940,418 6/1960 Penrod et a1 ..239/597 X [72] Invent l' La 3,002,700 10/1961 Mohring ..239/546 x [73] Assignee: Continental Can Company, Inc., 3,341,354 9/1967 Woods et a1. ..239/597 New York, N.Y. P E U d L K nmary xammeroy mg [22] filed: 1970 Att0rneyDiller, Brown, Ramik & l-lolt 21 A l.N 62550 l 1 pp 57 ABSTRACT Related Appllcafim Data This disclosure relates to a vapor knife for directing 2] Di i i of s No 75 5,889, A ,23 19 emission of a vapor stream. The vapor knife includes a Pat. No. 3,561,130.

hollow tubular member defining an interior cavity and having an elongated axially extending vapor emission opening which is in communication with the cavity [52] :LS. 2395235232253; and the exterior of the tubular member. The vapor [51] I'll. C l) knife directs a wide j of vapor against a p or [58] Field of Search ..239/455, 577, 546, 587, 602 coated article to efi'ect the treatment of the article with the vapor. [56] References Cited I 6 Claims, 7 Drawing Figures UNITED STATES PATENTS 1,272,031 7/1918 Gohmert ..239/455 PATENTEnAus 1 I972 3.680.795

sum 1 OF 6 FEED cam CARD D\SCHHRGE :Y fi RECOVERY 24 f 3 Q UNIT 25 i I 25 BLOWER B I vAPomzma uu PI 6. I.

INVENTOR RAYMOND P. GAUT E 5m 6 W1 ATTORNEY PATENTEDAUG 1 i972 SHEET 2 BF 6 ull:

llmuhllltmm 1 INVENTOR RUTZ ATTORNEY PATENTEDaus H972 I I 3.680.795

sum 5 or 6 INVENTOR RRYMOND FGHLITZ Aim d M ATTORNEY PATENTEDAUB 1 I922 sum 6 or 6 skidm.

INVENTOR R 0ND naau-rz ATTORNEY VAPOR KNIFE This application is a division of my copending application Ser. No. 755,889, filed Aug. 28, 1968, now US. Pat. No. 3,561,130, issued Feb. 9, 1971.

This invention'relates generally to methods and apparatus for fixing or fuzing medium deposited upon articles by the application of solvent vapor to the medium and more specifically to methods and apparatus for fuzing electrostatically deposited printing or coating medium by the application of hot solvent vapors.

The application of solvent vapors to a substrate or article having an image electrostatically produced thereon to effect fixing or fuzing of the toner medium forming such image is known in the art. Typical toner medium may include particles of approximately 41 percent n-butyl methacrylate and approximately 59 percent polystyrene or a combination of polyethylene and carbon black. The application of a solvent such as trichlorethylene in a vapor state to an image comprising particles of such toner results in a fixing or fuzing of the discrete toner particles such that the discrete toner particles are fuzed and fixed to the substrate.

In the fixing or fuzing of electrostatically printed images at production rates, the time required for each such fixing or fuzing operation must be substantially reduced if commercial production rates are to be economically attained. Further, the continual applications of solvent vapors to numerous articles in production line fashion requires special attention to the conservation of solvent which, without such special attention, would be substantially wasted in the escape of vapors from the fuzing or fixing station. Similarly, where the articles to betreated are of a card-like or panel-like nature, it is necessary to assure an even application of solvent vapors across the entirety of the printed area to effect a fuzing operation which is consistent throughout the image areaof the cards or panels. v

In view of the foregoing, it is a primary object of this invention to provide apparatus for fuzing deposited printing or coating medium at production rates and through the efficient employment of solvent vapor.

A further object of this invention is to provide apparatus for applying hot solvent vapor to printed or coated articles to effect fuzing of deposited medium at production rates.

Yet another object of this invention is to provide an improved vapor knife apparatus for directing a wide, jet of vapor against a printed or coated article.

An additional object of this invention is to provide in the aforementioned vapor knife an elongate vapor emission opening formed in a hollow tubular member of resilient material, which hollow tubular member is contractible toward its longitudinal axis and expandable away from such axis to effect variation in the width of the emission opening.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings. In the drawings:

FIG. 1 is a simplified diagrammatic view of apparatus in accordance with this invention and illustrates a vaporizing unit, vapor applying knive provisions fed from the vaporizing unit, vapor recirculation provisions vapor application, vaporizing and pumping provisions for directing vapor into the application area and recirculating vapor to the vaporizer.

FIGS. 3a and 3b, in combination, provide a vertical cross-sectional view taken along the line 3a, 3b-3a, 3b of FIG. 2 illustrating the vapor knife including a transversely arranged elongate. hollow tubular member, the vaporizer and vapor passage provisions communicating between the vapor knife and vaporizer and including a vapor pumping blower for moving vapor from the vaporizer for application by the vapor knife to card or panel-like articles.

FIG. 4 is an enlarged fragmentary vertical cross sectional view taken along the line 4-4 of FIG. 3a and illustrates a vapor emission opening adjusting stud extending transversely across the hollow tubular member of the vapor knife, a pivotally mounted gate supported by the cover provisions for contacting the leading edges of articles fed therepast and recirculation and reclaiming openings proximate the paper knife for withdrawing vapor from the area of application.

FIG. 5 is a fragmentary vertical cross sectional view taken along the line 5-5 of FIG. 4 and shows the ho]- low tubular member of the vapor knife mounted in end plate provisions and further illustrates the mounting of the pivotable gate within the cover provisions.

FIG. 6 is an enlarged fragmentary cross sectional view taken along the line 6-6 of FIG. 4 and shows the mounting of a pivotable damper within a chamber forming a portion of the vapor recirculation provisions.

Referring to the drawings in detail, indicated generally at 10 in FIG. 1 is a vaporizing unit or vaporizer including a liquid solvent depository or solvent retaining portion 11 having mounted therein a heating element 12 of a suitably selected heater combination 13. The vaporizer 10 further includes a vapor outlet 14 connected, via outlet duct provisions 15, with a blower 16 which draws vapor from the vaporizer 10 upon driving actuation from a variable speed drive unit and motor combination l7 and a drive train 18.

Hot solvent vapor produced by the heating of a quantity of liquid solvent maintained within the depository 11 is passed through the blower 16 to an output 20 thereof and, via further duct provisions 21, is passed to a vaporknife 22, to be more fully described hereinafter.

Card-like or panel-like articles, one of which is indicated at 23 in FIG. 1, are passed along a predetermined path of conveyance directly above the vapor knife 22 as by the provision of suitably selected conveying means 24 which may include a plurality of conveying or position determining rollers 25 disposed immediately upstream and downstream from the area of vapor application adjacent the knife 22.

Hot solvent vapors emitted in a jet from a vapor emission opening 26 in the vapor knife 22 are directed against an undersurface 27 of the card 23 during passage of the card along its predetermined path of conveyance. A chamber, generally indicated by the numeral 28 and housing the vapor knife 22, is connected via the duct 30 with the upper portion of the vaporizer 10. The blower 16, in withdrawing vapor from the upper portion of the vaporizer 10, applies a reduced pressure to the chamber 28 via the duct 30 and con sequently hot vapor is withdrawn into the chamber 28 and recirculated across the level of liquid solvent within the vaporizer 10.

The undersurface 27 of the cards 23 has deposited thereon, as by electrostatic printing, a predetermined image or coating of toner or printing medium soluble with respect to the solvent vaporized within the vaporizer 10. The application of hot vapor from the vapor knife 22 to the undersurface 27 of the card 23, then, fuzes or fixes the printed image or coating thereon. Such fuzing of the deposited printing or coating medium employs a limited quantity of the vapor emitted from the vapor knife 22. However, a relatively large portion of the hot vapor so emitted will be withdrawn into the chamber 28 through the

openings

31 and 32 defined therein on each side of the knife 22. Thus, a relatively large portion of the vapor emitted from the knife 22 is recirculated to the vaporizer for subsequent reapplication to cards to transmit past the knife 22.

On both the upstream and downstream sides of the chamber 28 are provided two further

vapor withdrawal passages

33 and 34 respectively. The passage 33 terminates in an opening 35 closely proximate and upstream from the opening 32 of the chamber 28. Similarly, the passage 34 terminates in an opening 36 closely proximate and downstream from the opening 31 of the chamber 28. Solvent vapor spilled over from the

openings

31 and 32 of the chamber 28 are withdrawn through the

openings

35 and 36 which serve as intakes to a solvent vapor reclaiming system generally indicated by the numeral 37. The solvent vapor reclaiming system 37 includes, in addition to the

passages

33 and 34, manifold duct provisions 38 combining vapor from the

passages

33 and 34 and passing the combined vapor to a further duct 41. Application of a reduced pressure to the duct 41 and correspondingly to the

passages

33 and 34 may be pro vided by a blower 42 having an output 43 feeding the vapor passing therethrough to a recovery unit 44.

The recovery unit 44 may be any of a number of commercially available, known or suitably selected assemblies capable of condensing hot vapor to its liquid state. Condensed solvent liquid is passed via a line 45 to a source of solvent or solvent supply tank 46 for subsequent revaporization by the vaporizer 10.

The supply tank 46 feeds the vaporizer 10 via a supply line 47 and a suitably selected float valve 48 responsive to the liquid solvent level within the vaporizer 10 to maintain a relatively constant predetermined liquid solvent level within the vaporizer.

It will be seen that hot solvent vapor escaping the recirculation provisions constituted by the chamber 28 and its associated duct 30 will pass into the

passages

33 and 34. It should further be noted that movement of a card 23 past the vapor knife 22 tends to carry therewith a quantity of the hot solvent vapor applied to the undersurface 27 and such quantity of vapor carried by the card 23 past the opening 31 of the chamber 28 is withdrawn from the undersurface 27 of the card upon approaching the opening 36 terminating the passage It should be noted that air or other atmospheric gases proximate the area of application of hot solvent vapor to the card 23 is substantially prevented from entering the chamber 28, with a resultant reduction in temperature in the recirculation path, inasmuch as such atmospheric gases are drawn into the

passages

33 and 34 prior to their possible entrance into the chamber 28 via the

openings

32 and 31. Accordingly, reduction in vapor temperature by the inclusion of atmospheric gases occurs in the reclaiming provisions of the system wherein a subsequent reduction in temperature for the purposes of condensation is intended and wherein such reduction in temperature by the inclusion of atmospheric gases does not effect the temperature of the hot vapor applied via the vapor knife 22.

Located atop the hot vapor application area is a cover 50 which aids in locating the cards 23 during their passage along the path of conveyance thereof and which substantially limits escape of solvent vapor prior to and following the passage of a card past the vapor emission opening 26 of the knife 22. Mounted within the cover 50 is a pivotable gate 51 having a lowermost portion which normally intersects the path of the conveyance of the card 23, causing the gate 51 to be pivoted upon contact with a leading edge of a card in transit through the area of vapor application.

Turning now to FIG. 2, there is shown therein a mounting frame 52 including a base 53 supporting thereon the generally indicated conveying provisions 24. Driving of the conveying provisions 24 may be effected through the employment of a suitably selected motor 54 and suitably selected driving provisions 55 which are only diagrammatically illustrated in FIG. 2, the conveying provisions 24 and drive 55 forming, per se, no part of this invention.

A series of mounting feet 56 and upright support members 57 support the vaporizer 10. The feed 56 are provided with threaded levelling means 58 adjustable to provide levelling of the vaporizer 10 with respect to the liquid solvent contained therein.

The frame 52 additionally includes a generally horizontally disposed mounting platform 60 connected via a generally vertically extending upright 61 with the base 53 and further supported by a diagonally extending support bar 62. The platform 60 mounts the variable speed drive unit and motor combination 17 which drives the blower 16 to withdraw vapors from the vaporizer l0 and recirculate vapors through the vaporizer. The combination 17 may be any of a number of suitably selected or commercially available combinations including a motor 63 and a variable speed output box 64 which, by actuation of a manually operable control 65, varies the speed imparted to the blower 16. The output from the variable speed drive unit and motor combination 17 is applied to the blower 16 via the drive 18 including an output pulley 66 over which is entrained a belt 67 in driving engagement with a further pulley 68 mounted upon a shaft 70, which shaft 70 serves as the input to the blower 16.

The blower 16 includes an input port 71 joined as at 72 with the duct provisions which communicate with the vaporizer 10 as indicated at 73. The output portion of the blower 16 is, as best seen in FIG. 3a, connected at the flanges 74 with a first passage providing duct 75 constituting a portion of the duct provisions 21 leading to the vapor knife 22. A second portion of the duct provisions 21 is provided by a shortupwardly extending duct 76 which increases in cross sectional area in an upward direction and which is connected with the duct 75 at the flanges 77. The chamber 28 forming a portion of the recirculation provisions described-hereinabove with respect to FIG. 1 includes a pair of front and-rear sloped

side walls

78 and 79, respectively, joined by a further connecting wall 81, all of which is best illustrated in FIGS. 3a and 3b.

Within the chamber 28 a further generally upwardly opening duct 82jcommunicates with the vapor knife 22 to supply hot solvent vapor thereto for application to a conveyed article. The generally upwardly opening duct 82 within the chamber 28 communicates with the up wardly extending duct 76 located externally of the chamber'28 via a connector 83 which extends through the connecting wall 81 of the chamber 28. The

ducts

76 and 82 are flanged at 84 and 85, respectively, and secured to the connector 83.

The duct 82 within the chamber 28 supplies hot vapor through'the chamber 28 to the vapor knife 22 and terminates at its uppermost portion in a partially cylindrical flange 86 which is secured to the knife 22 by a plurality of fasteners 87. The vapor supplying duct 82 communicates with the interior of the vapor knife 22 through an opening 88, best illustrated in FIG. '4, formed in a generally cylindrical, hollow tubular member 90 which constitutes the body of the vapor knife 22. The hollow tubular member 90 is of steel or similarly resilient material and, as best seen in FIGS. 3a and 3b extends transverse to the path of conveyance in the articles to be treated. The vapor emission opening 26 through which hot solvent vapors are applied to the undersurface 27 or cards or panels 23 in transit past the knife 22 is provided by an elongate narrow slot extending axially the length of the tubular member 90.

Adjustment of the width of the slot 26 in the circumferential direction with respect to the tubular member 90 is effected by the provision of a pair of studs 91 extending diametrically through the hollow tubular member 90 and having an enlarged head portion 92 and a washer 93 contacting the exterior of the hollow tubular member 90. Threadedly received upon the studs 91 is a nut 94 which contacts the exterior of the tubular member 90 diametrically opposite the head 92 and which may be affixed to the exterior of the tubular member as indicated in FIG. 4. It will be seen that turning of the stud 91 in a tightening direction will effect reduction in the width of the vapor emission slot 26 through a contraction of the tubular member 90 inwardly toward its longitudinal axis whereas a loosening of the stud 91 effects a relaxation in the pressure applied to the tubular member 90 allowing the enlargement of the vapor emission slot 26 under the inherent bias provided by the resilient material of which the tubular member 90 is formed.

Mounting of the vapor knife 22 within the chamber 28 is provided by a pair of mounting

plates

95, 96 having generally

annular grooves

97, 98,. respectively, formed in the interior surfaces thereof and receiving respective ends of the hollow tubular member 90 therein. An annular bearing member 100 is received in each of the

slots

97 and 98 and contacts the respective end of ,the tubular member 90 located therein. A suitably dimensioned wave washer 101 is located in each of the

slots

97 and 98 between the bottoms thereof and the washers 101, biasing the washers 101 into firm engagement with the respective ends of the tubular member 90. Each of the end or mounting

plates

95 and 96 is supported upon an upright apertured plate 102 as by a bolt 103. Each of these plates 102 includes a central aperture 104 throughwhich extends the tubular member 90 for reception in the

slots

97, 98. The apertured plates 102 terminate the cavity 28 in which the knife 22 is located on either side of the path of conveyance and ai'e joined with the

walls

78 and 79 ad- 20 jacent opposite ends of the vapor knife 22. The apertured plates 102 are mounting plates and 96 are supported by mounting provisions'generally indicated by the numeral 105'in FIGS. 3a and 3b which support the knife 22 upon the members of the suppoting base 63.

The chamber 28 into which hot vapor is drawn for recirculation terminates in a port 106 best seen in FIG. 3b, which port is connected, via a curved conduit 107, with a recirculated vapor intake port 108 provided at one end of the vaporizer l0. The'conduit 107 constitutes the duct 30 of FIG. 1 and is flanged and connected at its ends 110 and 111 to the chamber 28 and vaporizer 10, respectively.

Vapor recirculated through the chamber 28, conduit 107, across the level of the liquid within the vaporizer l0 and returned to the vapor knife 22 is maintained at an elevated temperature provided by both the heater 13 of the vaporizer l0 and an ancillary heater 112 mounted upon the mounting plate 95 and having an elongate heating element 113 extending into the interior of the hollow tubular member 90. The ancillary heater 112 may be a suitable commercially available heater and serves to further elevate the temperature of solvent vapor prior to jet-like emission from the elongate vapor emission opening 26 of the knife 22.

A suitable commercially available thermocouple temperature sensing device 114 may be mounted upon the mounting plate 96 with an elongate bi-metallic temperature responsive element 115 extending into the interior of the tubular member 90 to detect the temperature of the vapor just prior to emission from the opening 26. The thermocouple 114 may be employed to control the ancillary heater 112 for automatic control of the temperature of the hot solvent vapor applied to articles in transit past the knife 22.

The

passages

33 and 34 which terminate in

openings

35 and 36, respectively, through which vapor spilled over from the chamber 28 is withdrawn, are provided by two large downwardly depending

conduits

116 and 117, best illustrated in FIG. 4. The

conduits

116 and 117 are joined at a flanged end 118 thereof, best illustrated in FIG. 3b, with the manifold 38 for passage of vapor to the recovery unit 44 via the duct provisions 41. The

conduits

116 and 117 are spaced slightly from the chamber 28 and the space 120 so provided on each side of the chamber 28 may be employed for jacketing the chamber in insulating material to further help maintain the temperature of solvent vapor in the recirculation path.

It will be noted from FIG. 4 that the vapor emission opening 26 of the vapor knife 22 is directed angularly toward the path of the conveyance of the treated articles in an upstream direction with respect to that path of conveyance. The angle at which hot solvent vapor leaves the tubular member 90 may be adjusted and preset by a rotation of the tubular member 90 about the axis and within the

slots

97 and 98 of the mounting

plates

95 and 96 prior to fastening of the tubular member 90 with the duct 82. The age 51 pivotally mounted within the cover 50 overlying the vapor application area is mounted slightly upstream with respect to the vapor emission opening 26 and defines a surface 120 thereon which, in the absence of a card or panel 23 within the vapor application area, intersects the path of vapor emission from the vapor emission opening 26 to maintain vapor so emitted in the area of the

openings

31 and 32 of the chamber 28 to assure withdrawal of a substantial portion of the vapor through the chamber 28 for recirculation and to reduce substantially vapor losses along the conveyance path, absent the presence of a card or panel 23. A lowermost portion 121 of the gate 51 intersects the path of conveyance of the cards or panels 23 as defined by a set of guiding

provisions

122, 123 and 124. It will be seen from FIG. 4 that the lowermost portion 21 of the pivotally mounted gate 51 masks the leading edges of articles in transit along the path of conveyance from vapor emitted through the opening 26 of the vapor knife 22. Such masking action is of particular benefit where the cards or panels 23 are of corrugated medium extending parallel to the path of conveyance define openings in the leading edge of the paperboard panels susceptible to the entrance of vapor therein. The masking action provided by the portion 121 of the gate 51, then, prevents entrance of vapor into the openings which ordinarily would be exposed to the jet or stream of hot solvent vapor from the vapor knife 22. Additionally, it will be noted that the cover 50 has mounted therein a stop 122 for contacting the surface 120 of the gate 51 upon movement of the gate by the leading edge of a panel 23 in transit therepast. Once pivoted to the position shown in broken lines in FIG. 4, the lowermost portion 121 of the gate 51 contacts the upper surface of the panel to aid in maintenance of the panel in close proximity to the vapor emission opening 26 as vapor is applied to the undersurface of the panel.

As best seen in FIGS. 3a, 3b and 5, the cover 50 extends the full width of the path of conveyance and is provided with a pair of handles 123, facilitating the manual placement and removal of the cover 50. The cover 50 terminates in a pair of front and rear side walls 124 and 125, respectively, each of which has an aperture 126 formed therein closed by cover plate 127, fastened to the walls 124 and 125 as by the bolts 128. Through the apertures 126 extend a pair of bearing projections 130 integrally formed upon the interior surface of the cover plates 127 and defining a centrally located bore 131 therein. Within the bores 131 are received closely fitting cylindrical ends 132 of a rotatable gate support bar 133. The gate 51 is affixed, as at 134, upon the gate support bar 133, the cylindrical end 132 of the bar 133 being rotatably slidable within the bores 131. The walls 124 and 125 of the cover 50 are spanned by a hod 135 to complete the enclosure of the vapor application area.

Adjustments of the flow of hot solvent vapor into the chamber 28 is provided by the inclusion of a pair of dampers 140 and 141 immediately below the

openings

32 and 31, respectively, and adjacent the exterior of the hollow tubular member of the knife 22. The dampers and 141 are each supported upon a pair of damper support members 142, one of which is best illustrated in FIG. 6. The damper support members 142 are of generally cylindrical configuration relieved along a portion of the surface thereof as at 143 for connection with the dampers as by the screws 144. Each of the damper support members 142 extends into an aperture 145, four of which are provided in the upright plate 102. A shaft portion 146 extends through a further plate 147 affixed to the upright plate 102 and terminates in an end 148 of generally rectangular crosssection, exterior of the cavity 28 and allowing manual variation of the angle of inclination of the dampers 140 and 141. The shaft 146 is threaded as at 150 to allow the provision of a lock nut 151 suitable for maintaining the associated damper at a desired angle of inclination.

Air intake into the

passages

33 and 34 from adjacent the area of application of hot solvent vapor is adjustable by the provision of movable panel members 152 mounted upon the

conduits

116 and 117 as by the provision of outwardly extending studs 153 slidably maintained within slots 154 formed in the outermost walls of the

conduits

116 and 117. Threadedly maintained upon the studs 153 are adjustable retaining members 155 having projections 156 formed thereon for engagement with the walls of the

conduits

116 and 117 adjacent the slots 154. Movement of the panel members 152 as indicated by the broken line illustration in FIG. 4 allows reduction in the cross sectional area of the

openings

35 and 36 into the

passages

33 and 34, respectively, and allows restriction of air flow into such passages by movement of the panel members 152 into closer proximity with the path of conveyance of the cards or panels 23.

Varying the angle of inclination of the dampers 140 and 141 adjust the amount of hot solvent vapor spilled over from the chamber 28 to the

passages

33 and 34, while adjusting the position of the movable panel members 52 allows an adjustment in the amount of air or atmospheric gases entering the

passages

33 and 34, thus preventing the entrance of excess atmospheric gases such as would cause withdrawal of those gases into the chamber 28.

As set forth hereinabove, a portion of the hot solvent vapor applied to articles in transit along the path of conveyance is carried with such articles and ultimately withdrawn into the passage 34. The rate of vapor production, then, by the vaporizer 10 should be adjusted to provide vapor as required by the use thereof in fixing or fuzing the coating or printing medium on the undersurface of the panels 23, by the withdrawal of vapor carried with the panels in their movement through the vapor application area, by the slight vapor losses occurring in the system and to provide an amount of vapor spilled over past the

openings

31 and 32 into the chamber 28 to be withdrawn by the

passages

33 and 34 for conversion to the liquid state.

It will be seen from the foregoing that adjustment of the vaporization of the vaporizer 10, the driven rate of the blower 16 and the position of the dampers 140 and 141 and the panel members 154 allows employment of the system to maintain elevated vapor temperatures in the recirculation path, decreasing the time required in each fuzing operation, with minimum loss of solvent and with little or no entry of atmospheric gases into the recirculation path.

While two methods and apparatus described hereinabove represent preferred forms of the embodiment, it will be readily apparent that many variations may be made therein without departure from the spirit of the invention embodied therein.

Iclaim:

l. A vapor knife for directing emission of a vapor stream including a hollow tubular member having a single longitudinal axis defining an interior cavity and an elongate axially extending vapor emission opening communicating between said cavity and the exterior of said tubular member, an input opening communicating with said interior cavity for connection with a vapor supply, end plate mounting means closing said hollow tubular member at opposite ends thereof and mounting said tubular member for angular movement about said longitudinal axis to determine the direction of vapor emission from said vapor emission opening.

2. A vapor knife according to claim 1 wherein said end plate mounting means includes a plate at each end of said hollow tubular member having an annular groove formed therein, each said groove accepting an end of said tubular member for sliding movement within said groove to allow angular adjusting movement of said tubular member.

3. A vapor knife according to claim 1 further comprising means for contracting said hollow tubular member inwardly toward its longitudinal axis to adjust the circumferential extent of said elongate vapor emission opening, each said groove being of greater radial extent that the end of said hollow tubular member accepted therein to allow contracting inwardly within said groove. 1

4. A vapor knife according to claim 1 wherein said tubular member is of resilient material, and further including means for contracting said tubular member toward its longitudinal axis to decrease the circumferential dimension of said elongate vapor emission opening.

5. A vapor knife according to claim 4 wherein said means for contracting includes at least one elongate stud extending laterally through said tubular member and bearing enlarged tubular member contacting members at opposite ends thereof and in contact with the exterior of said tubular member, one of said enlarged tubular member contracting members being adjustably received upon said stud for contracting said tubular member against the bias of said resilient material upon movement inwardly with respect to said tubular member and for allowing expansion of said tubular member under the bias of said resilient material upon movement outwardly with respect to said tubular member.

6. A vapor knife according to claim 1 further including heater means housed within said interior cavity for heating vapor just prior to emission from said elongate

Claims

1. A vapor knife for directing emission of a vapor stream including a hollow tubular member having a single longitudinal axis defining an interior cavity and an elongate axially extending vapor emission opening communicating between said cavity and the exterior of said tubular member, an input opening communicating with said interior cavity for connection with a vapor supply, end plate mounting means closing said hollow tubular member at opposite ends thereof and mounting said tubular member for angular movement about said longitudinal axis to determine the direction of vapor emission from said vapor emission opening.

3. A vapor knife according to claim 1 further comprising means for contracting said hollow tubular member inwardly toward its longitudinal axis to adjust the circumferential extent of said elongate vapor emission opening, each said groove being of greater radial extent that the end of said hollow tubular member accepted therein to allow contracting inwardly within said groove.

6. A vapor knife according to claim 1 further including heater means housed within said interior cavity for heating vapor just prior to emission from said elongate vapor emission opening.