Abstract:
A feeder tube assembly for a feeder bowl of a glass melting furnace forehearth. The feeder tube assembly has an horizontally extending elongate support arm, and a feeder tube that is carried by the support arm at a location near an end of the support arm. The feeder tube is held in place by a clamping ring that engages a flange of the feeder tube at an end of the feeder tube. The clamping ring is releasably held in engagement with the flange of the feeder tube by a plurality of latch mechanisms that are circumferentially spaced apart. Each latch mechanism has a lever with a rounded cam surface and a handle that extends away from the cam surface and is pivotally attached to a support member. The support member, in turn is pivotally attached to a fixed member, and pivoting of the pivoted support member relative to the fixed member is effective to swing the lever out of interfering relationship with the clamping ring to facilitate removal of the clamping ring.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/130,313, in which I am named as an inventor, which was filed on Aug. 7, 1998 now U.S. Pat. No. 6,151,918. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a feeder tube assembly for a feeder bowl of a glass melting furnace forehearth. More particularly, this invention relates to a clamp down system for releasably clamping a feeder tube in its operating position. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,718,741 (Hull et al.), which is assigned to the assignee of this application, the disclosure of which is incorporated herein by reference, discloses a forehearth for cooling a stream of molten glass as it flows from a glass melting furnace to a forming machine for forming the molten glass into finished products, for example, hollow glass containers of the type widely used in packaging various food, beverage and other products. In the arrangement of the &#39;741 Patent, and in a variety of other types of forehearths, molten glass flows downwardly through an opening, or a plurality of openings, in the bottom of a feeder bowl at an end of the forehearth that is remote from the end into which molten glass from the melting furnace flows. 
     To control the flow of molten glass from a forehearth feeder bowl, a vertically extending, refractory feeder tube is provided with its lowermost end immersed in the feeder bowl to a level slightly above the inside surface of the bottom of the feeder bowl and surrounding the opening(s) at the bottom of the feeder bowl, and the ceramic tube is caused to rotate slowly during the operation of the forehearth to ensure a proper mixing and temperature uniformity of the molten glass flowing from the feeder bowl. A feeder bowl refractory tube with a tube drive system of this general type is disclosed in U.S. Pat. No. 5,660,610 (DiFrank), which is also assigned to the assignee of this application, the disclosure of which is also incorporated by reference herein. Other glass forehearth feeder bowl feeder tube arrangements are described in U.S. Pat. No. 5,693,114 (Scott), U.S. Pat. No. 4,514,209 (Mumford), and U.S. Pat. No. 4,478,631 (Mumford), the disclosure of each of which is also incorporated by reference herein. 
     From time to time during the operation of a glass manufacturing system of a type employing a forehearth feeder bowl feeder tube of the type described above it is necessary to remove the feeder tube and/or the feeder bowl for repair or replacement. In the case of the replacement of the feeder bowl, the feeder tube must also be swung horizontally out of the way of the feeder bowl as well as being lifted vertically so that its lower edge clears the upper extent of the feeder bowl. It is also necessary from time to time to be able to adjust the height of the feeder tube. As a feeder tube of this type is quite massive, very large forces are required to lift it from its operating position. Heretofore, counterweighted lift mechanisms were employed for this purpose, and these mechanisms typically employed gear boxes with considerable backlash, thus making precise positioning and motions of the feeder tube very difficult. Moreover, in these arrangements, precise adjustment of the position of the feeder tube in a horizontal plane, in X and/or Y directions, was difficult to achieve in that the horizontal motions of the counterweight lift mechanisms could not be isolated along X or Y axes. Further, counterweighted lift mechanisms are cumbersome because of the dead weights employed in them, and the vertical feeder tube slide supports are subject to wear during up and down tube adjustments, which can impart a wobbling motion to the tube support system and thereby lead to undesired glass gob weight variation in a feeder bowl used in conjunction with a glass container forming machine of the individual section (I.S.) type. Also, from time to time, it is necessary to replace a feeder bowl itself. In the prior art, this required removal of the entire feeder tube mechanism itself. A feeder tube in apparatus of the type described is releasably held in place by a circumferentially spaced apart plurality of clamps. Heretofore, it has been difficult to release such clamps, which typically involved threaded members, because of the tendency of such members to corrode in the high temperature environment of a feeder tube installation and the need for workers to wear temperature resistant gloves during this procedure, gloves that are quite bulky 
     SUMMARY OF THE INVENTION 
     According to the present invention of the aforesaid co-pending U.S. patent application, the aforesaid and other problems associated with prior art glass forehearth feeder bowl feeder tube lift systems are avoided by a feeder tube lift system that employs a single, multiple shaft, servo motor operated, ball screw lift mechanism of sufficient capacity to sustain a cantilevered feeder tube support mechanism with minimal deflection. Such a lift mechanism involves no, or very little, backlash in its motions, thereby permitting precise control of the elevation of the lift tube in the feeder bowl, which is important in achieving accurate control of glass gob weight in an I.S. machine glass container manufacturing operation. 
     The feeder tube lift mechanism of the present invention is also capable of true isolated adjustments in a horizontal plane, both along X and Y axes, and it can be moved without slide wear, thereby avoiding introduction of wobbling motion to the tube support system. The servo motor powered ball screw lift mechanism of the present invention is lubricated by a lubricant that is recirculated within a closed system to ensure long life for bearings of the mechanism and the ball roller nut, and avoiding lubricant leakage and the need for lubricant replacement. 
     According to the invention of the aforesaid co-pending U.S. patent application, and according to an improved version of such invention according to this patent application, there is provided an improved clamp for releasably clamping a feeder tube engaging clamping ring in its clamping position against a flange of the feeder tube while the feeder tube is in its operating position with respect to the rotatable support. Each such clamp has a variable radius cam that is rotatable about a radially extending horizontal axis to make secure contact with the clamping ring regardless of the elevation of the feeder tube, but which is capable of being swung out of interfering contact with the feeder tube to permit the feeder tube to be removed for repair or replacement after first removing the clamping ring used to engage a flange of the feeder tube. 
     Accordingly, it is an object of the present invention to provide an improved clamp down system for clamping a feeder tube of the type employed in a glass forehearth feeder bowl. More particularly it is an object of the present invention to provide a clamp down-system that is rapidly releasable in that it does not require threaded fasteners in its design or installation. 
     For further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof, to the detailed description of the preferred embodiment and to the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a fragmentary elevational view of a feeder tube assembly incorporating a clamp down system according to the preferred embodiment of the present invention; 
     FIG. 2 is a plan view of the feeder tube assembly of FIG. 1; 
     FIG. 3 is a sectional view taken on line  3 — 3  of FIG. 2; 
     FIG. 4 is a fragmentary view, at an enlarged scale, of a portion of the feeder tube assembly shown in FIG. 1; 
     FIG. 5 is a fragmentary sectional view taken on line  5 — 5  of FIG. 2; 
     FIG. 6 is a sectional view taken on line  6 — 6  of FIG. 5; 
     FIG. 7 is a fragmentary perspective view of a portion of the feeder tube assembly of FIGS. 1-6; 
     FIG. 8 is a fragmentary elevational view, partly in cross section, of a portion of the feeder tube assembly of FIGS. 1-6; 
     FIG. 9 is a view similar to FIG. 8 at a right angle thereto; 
     FIG. 10 is a plan view of an element of the feeder tube assembly of FIGS. 1-6; 
     FIG. 11 is a sectional view taken on line  11 — 11  of FIG. 10; and 
     FIG. 12 is an exploded, perspective view of a portion of the apparatus illustrated in FIGS. 8 and 9; 
     FIG. 13 is a view similar to FIG. 7 illustrating a modified form of the apparatus illustrated therein; and 
     FIG. 14 is a fragmentary perspective view of a feeder tube assembly that incorporates a plurality of the devices of FIG.  13 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A feeder tube assembly in which the preferred embodiment of the present invention is used is identified generally by reference numeral  20  in the drawing. The feeder tube assembly  20  includes a refractory feeder tube  22  which, as is shown in FIG. 3, is adapted to be inserted into a molten glass feeder bowl B at the outlet end of a generally horizontally extending molten glass cooling forehearth, otherwise not shown, which may be of conventional construction. The feeder tube  22  is vertically oriented in the feeder tube assembly  20 , and its lowermost end is positioned slightly above the inside surface of the feeder bowl B, to thereby allow molten glass to flow through the space below the feeder tube  22  to exit through openings O at the bottom of the feeder bowl B. 
     The feeder tube  22  has an outwardly projecting flange  24  at its upper end, and the flange  24  is clamped in a clamping ring subassembly  86 , FIG. 3, which is provided with lifting eyes  18 , FIGS. 2,  3 , and serves to support the feeder tube  22  on an inwardly a projecting flange  26  of a rotatable ring subassembly  28 . The rotatable ring subassembly  28  is cantilevered at the end of a support arm  30 , and the subassembly  28  includes an upwardly facing ring gear  32 , FIG. 2, and is caused to rotate slowly with respect to the support arm  30  by the engagement of the ring gear  32  by a driven pinion  34  at an end of a driven rod  36 , which is driven by a motor  38  acting through a speed reducer  40 , all of which are supported on the support arm  30  at an end opposed to the end on which the feeder tube  22  is suspended. The rotation of the feeder tube  22  helps to properly mix the molten glass in the feeder bowl B to thereby ensure proper homogeneity and temperature uniformity of the molten glass exiting through the openings O, FIG.  3 . 
     The support arm  30  is supported along a vertically extending axis A that extends through a handle  42 , which serves to lock the support arm in a non-adjustable and a non-pivotable position as will be hereinafter described more fully. The support arm  30  is also adjustably supported for precisely controllable motion along the axis A on a vertically extending servo motor powered precision linear actuator  44 , FIG. 1, a cylinder portion  44   a , FIG. 5, of which is secured to the framework  46  of the feeder tube assembly  20 . The linear actuator  44  is of a type that is available from E-Drive Design, Inc. of Glastonbury, Conn. under the product designation Model EA2S-7.312-L/D 1836, and will be subsequently described in greater detail. The support arm  30  has an opening  48 , FIG. 5, extending therethrough concentric with the axis A and generally concentric with the longitudinal central axis of the linear actuator  44 . A spaced apart plurality of rods  50  extend outwardly and upwardly from the linear actuator  44  and are caused to reciprocate in unison along vertical axes by the actuation of the linear actuator  44 . The rods  50  are non-rotatably received in a block  52  of a composite adjustment mechanism  54 , which is supported on an inverted cup-shaped structure  56  that is secured to the upper surface of the support arm  30 , FIG.  5 . 
     The adjustment mechanism  54  includes an upper plate  58 , and the support arm  30  is moveable relative to the upper plate  58  along opposed spaced apart slot  60  in the structure  56 , which extend generally parallel to the longitudinal axis of the support arm  30  to provide for precisely controllable adjustment of the support arm  30 , and thereby of the feeder tube  22 , in the X direction. To accomplish such adjustment, an adjusting screw  62 , which is threadably received in the structure  56   a , has an inner end that engages the upper plate  58 , and the turning of the adjustment screw  62  is effective to move the support arm  30  to or fro in the X direction relative to the adjustment mechanism  54 , whose position in an horizontal plane is fixed by virtue of the attachment of the linear actuator  44  to the framework  46 , as described. 
     The adjustment mechanism  54  also includes a lower plate  64 , and the support arm  30  is moveable relative to the lower plate  64  along opposed, spaced apart slots  66  in the cup-shaped structure  56 , which extend transversely of the longitudinal axis of the support arm  30 , to provide for precisely controllable adjustment of the support arm  30 , and thereby of the feeder tube  22 , in the Y direction. To accomplish such adjustment, an adjustment screw  68 , which is threadably received in an extension of the upper plate  58 , has an inner end that engages a boss portion  70  of the cup-shaped structure  56 , and turning of the adjustment screw  68  moves the support arm to or fro in the Y direction relative to the adjustment mechanism  54 . Of course, when the handle  42  is tightened down against the boss  70 , the support arm  30  will be frictionally prevented from moving relative to the adjustment mechanism  54 , either in the X direction or the Y direction. 
     Because of the high temperature environment in which the feeder tube  22  is used, it is important to cool the end of the support arm  30  from which the feeder tube  22  is suspended. To that end, an annular passage  72 , FIGS. 1,  3 , is provided in the support arm  30  surrounding and extending generally concentrically of the feeder tube  22 , and cooling air or other cooling fluid is caused to flow through the passage  72  from inlet and outlet lines  74 ,  76 , respectively. Further, a generally semi-cylindrical heat shield  78  is suspended form the support arm  30  at a location partly surrounding the upper end of the linear actuator  44 , and between the linear actuator  44  and the feeder tube  22 , to retard heating of the linear actuator  44  by heat radiated from the feeder bowl B. 
     The flange  24 , FIG. 3, of the feeder tube  22  is securely, but releasably, held in engagement with the flange  26  by a plurality of circumferentially spaced apart latch mechanisms, each generally identified by reference numeral  80 , FIG. 2, three such latch mechanisms being shown in FIG.  2 . Each latch mechanism  80  comprises a lever  82 , FIG. 3, with a handle portion  82   a  at an end thereof and an enlarged cam portion  82   b  at an opposed end, FIG. 7 the lever  82  is pivotably connected to a support member  84  about an axis C and, when the lever extends vertically, the cam portion  82   b  securely engages an upper surface of the clamping ring  86  which engages the flange  24  of the feeder tube  22  to forcibly press the flange  24  into its desired operating position. When the lever  82  is pivoted to a horizontal orientation, the cam portion  82   b  no longer engages the ring  86 , FIG.  7 . In this position, the feeder tube  22  may be removed from the feeder bowl B by a simple lifting motion, using the lifting eyes  18 , FIGS. 2 and 14. The latch mechanisms  80  are moveable out of alignment with the feeder tube  22  by pivotably connecting the support member  84  to a fixed structure  88  about an axis D. In that regard, the support member  84  is slidable toward an enlarged area  88   a  of the fixed structure  88 , where it can then be pivoted about the axis D out of interfering relationship with the clamping  86 . Before installing a new feeder tube  22 , the support arm  30  should be elevated so that the new feeder tube  22  does not contact the feeder bowl B. 
     The pivoting of the support arm  30  about the axis A is done when it is desired to replace a feeder bowl B. After releasing the feeder tube  22  from its engaged position by the release of the latch mechanisms  80 , as heretofore described, and after the actuation of the linear actuator  44  to lift the support arm  30  to an elevation such that the bottom of the feeder tube  22  is free of the feeder bowl B, the feeder tube  22  is then hoisted from the subassembly  28 . To this end, the upper plate  58  of the adjustment mechanism  54  is pivotable with respect to the lower plate  64 , after removal of an alignment pin  114  that circumferencially aligns the upper plate  58 , the lower plate  64  and the block  52  with respect to one another during the operation of the feeder tube assembly  20 . 
     The linear actuator  44  is powered by an a.c. servo motor  90 , which is co-axially connected to the actuator  44 , though it is contemplated that the connection can be by way of parallel axes with a V-belt or other drive extending therebetween. In any case, an assembly including the actuator  44  and the servo motor  90  is available from E-Drive Design of Glastonbury, Conn., as heretofore described. As is shown in FIG. 8, the motor  90  has a hollow output shaft  92 . The hollow output shaft of the motor  90  is slipped onto an input shaft  94  of the linear actuator  44  (FIGS.  8  and  11 ), which has an internal ball screw drive  96 . The ball screw drive  96  translates rotary motion of the shaft  92  into linear motion of an annular member  98 , either to or fro depending on the direction of rotation of the shaft  92 . 
     The annular member  98  may be manually positioned by turning a lever  102 , which is fixed to the shaft  92 . The shaft  92  extends to a level below the motor  90 , actually below the level of an arcuate heat shield  100  that protects the motor  90  from thermal radiation from the feeder bowl B, and the lever  102  extends outwardly from the shaft  92 . The lever  102  has a handle  104  projecting downwardly therefrom, at a location radially outwardly of the shaft  92 , and the shaft  92  may be turned by manually engaging the handle  104  and using it to turn the lever  102 . 
     The motor  90  is provided with an annular brake  106  that rotates with the shaft  92 , and the brake  106  is selectively engageable by a double-ended constricting band  108 . The band  108 , when in its non-constricting mode, does not engage the brake  106  and provides no braking effect in such mode. However, the band  108  can be selectively tightened by the actuation of a pneumatic cylinder  110  acting through a linkage system  112 , and, when the cylinder  110  is retracted, as shown in FIG. 12, the band  108  will be constricted to engage the brake  106 , thus retarding turning action of the shaft  92 ,  94  and thereby locking the support arm  30  in a desired elevation. 
     The linear actuator  44  requires constant lubrication in service, and to that end a plurality of lubricating oil inlet lines  116 ,  118 ,  120 ,  122 ,  124 ,  126  and  128  (FIG. 4) to deliver lubricating oil from a common source (not shown) to various locations of the linear actuator  44 . These locations include inlets  130 ,  132  (FIG. 11) of the cylinder  44   a  of the linear actuator  44  and each of the four (b) rods  50  (FIG. 6) that extend therefrom. The lubricating oil is collected at the bottom of the cylinder  44   a  and returned to the source for recycling, by way of a return line  134  (FIG. 4) preferably after being filtered and cooled if necessary, with a supply of fresh, make-up oil being provided to make up for any oil losses in the system. The lubricating system, as described, is a closed system that provides adequate lubrication for all moving surfaces while simultaneously minimizing lubricant losses in a hot and relatively inaccessible environment and serving to conserve a product derived from expensive and irreplaceable natural resources. 
     In FIGS. 13 and 14 elements that differ from, but correspond in function to, elements of the embodiment of FIG. 1-12 are identified by  200  series reference numerals, the last two digits of which are the two digits of the corresponding element of the embodiment of FIGS. 1-12. 
     FIG. 13 illustrates a latch mechanism  280 , and three such latch mechanisms  280  are illustrated in FIG. 14 in circumferentially spaced apart relationship to one another. Each latch mechanism  280  comprises a lever  282  with a handle portion  282   a  at an end thereof and an enlarged cam portion  282   b  at an opposed end, the handle portion  282   a  extending from a position that is between the ends of the cam portion  282   b  whereas the handle portion  82   a  of the lever  80  of the embodiment of FIG. 7 is aligned with an end of the cam portion  82   b . In that regard, the cam portion  282   b  of the lever  282  has a profile that is more universally applicable to various installations than is the profile of the cam portion  82   b  of the lever  82  because of variations in the thickness of the flange portion  24  of the feeder tube  22  from installation to installation. The lever  282  is pivotally connected to a support member  84  about an axis and when the lever  282  extends vertically, the cam portion  282   b  securely engages a recessed bottom in a notch  286   a  of a clamping ring  286 , which engages the flange  24  of the feeder tube  22  to forcibly press the flange  24  into its desired operating position. The use of the notch  286   a  in the clamping ring  286  facilitates better engagement of the clamping ring  286  by the cam portion  282   b  of the lever  282 , and it also facilitates easier release of the clamping action of the lever  280  when it is desired to change the feeder tube  22  when the lever  282  is pivoted to a horizontal orientation, the cam portion  282   b  no longer engages the clamping ring  286 . In this position, the clamping ring  286  may be lifted out of position, as is shown in phantom in FIG. 14, to thereupon permit the feeder tube  22  to be lifted out of position, it first being necessary to move each of the latch mechanisms  280  out of interfering alignment with the clamping with the clamping ring  286  and the feeder tube  22 . This is done by sliding the support member  84  to the enlarged area  88   a  of the fixed structure  88  and then by pivoting the support member  84  about the axis D out of interfering relationship with the clamping ring  286 . 
     Although the best mode contemplated by the inventor for carrying out the present invention as of the filing date hereof has been shown and described herein, it will be apparent to those skilled in the art that suitable modifications, variations, and equivalents may be made without departing from the scope of the invention, such scope being limited solely by the terms of the following claims and the legal equivalents thereof