MXPA99006878A - System of elevation of the pipe of feeding of an antecri - Google Patents

Abstract

The present invention relates to a feeding tube assembly for a feeding bowl of a forehearth of a furnace for the melting of glass. The feed tube assembly has an elongated support arm that extends horizontally, and a feed tube that is supported by a support arm to a location near one end of the support arm. The feed tube is rotatable about its longitudinal central axis with respect to the support arm, and the support arm supports steering elements for rotation of the feed tube about its longitudinal central axis. The support arm is supported by a linear actuator operated by a servo motor that extends vertically, and the lift of the support arm is adjusted by the actuation of the linear actuator, a releasable brake is provided for the prevention of servo motor rotation when it is desired to prevent a change in the lifting of the support arm. The relative support arm position with the linear actuator is independently adjustable in both cases, by the support arm longitudinally and by the support arm transversely and by the support arm is rotary with respect to the linear actuator when it is desired to replace a tube of food supported by means of this or the feeding bowl directly below is

Description

SYSTEM OF ELEVATION OF THE FEED PIPE OF AN ANTECRISOL BACKGROUND OF THE INVENTION Field of the invention This invention describes a feed tube assembly for a feed bowl of a forehearth for heating in the glass melt. More particularly, this invention describes a clamping removal system, for the releasable clamping of a feeding tube in its operating position :.

Description of the prior art U.S. Patent 5,718,741 (Hull et al.), Which is assigned to the attorney of this application, of which the description for reference is incorporated herein, which describes a forehearth for cooling a stream of molten glass which flows from a glass melting furnace to a molding machine for the formation of molten glass in final products, for example, glass containers REF .: 30896 hollows of the type widely used in the packaging of various foods, beverages and other products. In the arrangement of the? 741 patent, and in a variety of other types of antecrystals, the molten glass flows down through an opening, or a plurality of openings, into the bottom of a feeding bowl at the end of the forehearth which is remote from the end into which the molten glass from the melting furnace flows.

For controlling the flow of molten glass from a forehearth feed bowl, a refractory feeding tube is provided, which extends vertically with its lower end submerged in the feed bowl at a level slightly above the inner surface of the bottom of the feeding bowl and surrounding the opening (s) in the bottom of the feeding bowl, this causes the ceramic tube to rotate slowly during the operation of the forehearth to ensure proper mixing and a uniform temperature of the molten glass flowing from the feeding bowl. A refractory feeding bowl tube with a tube driving system of this type is generally described in US Patent No. 5,660,610 (DiFrank), which is assigned to the agent of this application, of which the description for reference. Other feeding tube arrangements of the forehearth feed bowl for glass are described in U.S. Patents 5,693,114 (Scott), 4,514,209 (Mumford), and 4, 78, 631 (Mumford), the description of each of which is also incorporated herein. them for reference.

From time to time during the operation of a glass manufacturing system of a type employing a feeding tube of the forehearth bowl of the type described above it is necessary to remove the feeding tube and / or the feeding bowl for repair or replacement. In the case of replacement of the feeding bowl, the feeding tube must also be swiveled horizontally from the path of the feeding bowl as well as raised vertically so that its lower edge lightens the extension or higher area of the feeding bowl. It is also necessary from time to time to allow adjustment of the height of the feeding tube. As a feeding tube of this type is completely solid, very large forces are required for its lifting from its operating position. The counterbalanced lifting mechanisms for this purpose were once used, and these mechanisms typically employed gearboxes with considerable play between teeth, thus making movements and precise positioning of the feeding tube very difficult. Moreover, in these arrangements, the precise adjustment of the position of the feeding tube in a horizontal plane, in the directions X and / or Y, are difficult to perform in which the horizontal movements of the counterweight lifting mechanisms can not be made. isolate along the X or Y axes. In addition, the counterweight lifting mechanisms are difficult to handle due to the dead weights used in them, and the sliding supports of the feeding tube are subject to wear during tube adjustments up and down, which can distribute a movement of wobble to the tube support system and therefore lead to weight variations of large amount of unwanted glass in a feeding bowl used in conjunction with-- a glass container molding machine of the individual section type (IS) . Also, from time to time, it is necessary to replace the same feeding bowl. In the prior art, it is required to remove the same mechanism from full feeding tube. A feeding tube in the apparatus of the type described is releasable in one place by a plurality of clamps spaced circumferentially apart. At another time, it had been difficult to release such clamps, which typically involved threaded members, due to the tendency of such members to corrosion in the high temperature environment of a power pipe installation and the need for workers to use. temperature resistant gloves during this procedure, gloves that are completely bulky.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention of the co-pending US patent application, the above problems and other problems associated with the prior art of feeding tube feeding systems of a glass forehearth feeding bowl are avoided by a system of lift of the feeding tube using a single ball screw lifting mechanism, operated by a multiple arrow servo motor of sufficient capacity to support a feeding tube support mechanism with brackets and with a minimum deviation. Such a lifting mechanism may not involve, or do so in a minimum amount, play between teeth in their movements, therefore, precise control of the tube lift in the feeding bowl is allowed, which is important in terms of control Exact weight of the glass in the operation of an IS machine of manufacture of a glass container.

The lifting mechanism of the feeding tube of the present invention is also susceptible to true isolated adjustments in a horizontal plane, along both X and Y axes, and this can be moved without slipping, therefore the introduction of wobble movements to the tube support system. The ball screw lifting mechanism operated by a servo motor of the present invention is lubricated by a lubricant that is recirculated within a closed system to ensure long life for the parts of the mechanism and the ball roller nut, as well as to avoid dripping lubricant and the need for lubricant replacement.

In accordance with the invention of the aforementioned co-pending US patent application, and in accordance with an improved version of such invention in accordance with this patent application, an improved clamp is provided for the releasable fastening of a clamping ring that engages to the feeding tube in its clamping position against a flange of the feeding tube while the feeding tube is in its operating position with respect to the rotating support. Each clamp has a variable radius cam that is rotatable about a horizontal axis extending radially to make a secure contact with the clamping ring regardless of the elevation of the feed tube, but which is capable of being rotated from the Interference contact with the feed tube to allow the feeding tube to be removed for repair or replacement after the first removal of the clamping ring used to engage a feed tube flange.

Accordingly, it is an object of the present invention to provide a fastening release system for fastening a supply tube of the type employed in a feeding bowl of a glass forehearth. More particularly it is an object of the present invention to provide a fastening release system that is readily releasable in which threaded fasteners are not required in their design or installation.

For a further understanding of the present invention and objectives thereof, attention is drawn to the drawings and the following brief description thereof, for the detailed description of the preferred embodiment and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a fragmentary elevational view of a feed tube assembly incorporating a fastening release system in accordance with the preferred embodiment of the present invention; Figure 2 is a plan view of a feed tube assembly of Figure 1; Figure 3 is a view of a section taken from line 3-3 of Figure 2; Figure 4 is a fragmentary view, on an enlarged scale, of a part of a feed tube assembly shown in Figure 1; Figure 5 is a fragmentary sectional view taken on line 5-5 of Figure 2; Figure 6 is a sectional view taken on line 6-6 of Figure 5; Figure 7 is a fragmentary perspective view of a part of the feed tube assembly of Figures 1-6; Figure 8 is a fragmentary elevational view, partly in cross section, of a portion of the feed tube assembly of Figures 1-6; Figure 9 is a view similar to Figure 8 at a right angle thereof; Fig. 10 is a plan view of an element of the feed tube assembly of Figs. 1-6; Figure 11 is a sectional view taken on line 11-11 of Figure 10; Y Figure 12 is an exploded, perspective view of a part of the apparatus illustrated in Figures 8 and 9; Figure 13 is a view similar to Figure 7 illustrating a modified form of the apparatus shown therein; Y Fig. 14 is a fragmentary perspective view of a feed tube assembly incorporating a plurality of devices of Fig. 13.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY A sizable or mounting feeding tube in which the preferred embodiment of the present invention is used is generally identified by reference numeral 20 in the drawings. The feed tube assembly 20 includes a refractory feed tube 22 which, as shown in Figure 3, is adapted for insertion into a molten glass feed bowl B at the outer end of a cooling forehearth furnace. of molten glass extending generally horizontally, otherwise not shown, which may be of a conventional construction. The feed tube 22 is oriented vertically in the feed tube assembly 20, and its lower end or tip is at a position slightly above the inner surface of the feed bowl B, to allow the molten glass to flow through of the space under the feeding tube 22 to exit through the openings O which are located in the bottom of the feeding bowl B.

The supply tube 22 has a flange 24 projecting outwardly at its upper end, and the flange 24 is clamped in a sub-assembly p ° of clamping ring, Figure 3, which is provided with lifting eyes 18, Figure 4 , and serves to support the feeding tube 22 on a flange 26 projecting into a sub-assembly 28 of a rotary ring. The semi-rotary ring assembly 28 is flown at the end of a support arm 30, and the semi-assembly 28 includes a toothed wheel 32 facing upwards, Figure 2, and is caused to roll slowly with respect to the arm of the arm. support 30 by the gear of the gear 32 by a transmission pinion 34 at one end of a transmission bar 36, to which movement is transmitted by means of a motor 38 acting through a speed reducer 40, all of which are supported on the support arm 32 at the opposite end on which the feeding tube 22 is suspended. The rotation of the feed tube 22 aids in the proper mixing of the molten glass in the feed bowl B with which proper homogeneity and uniform temperature is ensured to the molten glass exiting through the openings O, Figure 3.

The support arm 30 is supported along a vertically extending axis A extending through a flywheel 42, which serves to secure the support arm in a non-pivotable and non-adjustable position as described herein. later. The support arm 30 is also adjustable in its support for precise control of movement along the axis A on a precision linear actuator 44 operated by a vertically extended servo motor, FIG. 1, a cylindrical portion 44a, FIG. 5, FIG. which is secured to the frame 46 of the feed tube assembly 20. The linear actuator 44 is of a type that is available from E-Drive Desing, Inc., of Glastonbury, CT, under the product description Model EA2S-7.312-L / D-1836, and is subsequently described in greater detail. The support arm 30 has an opening 48, which extends concentrically with the axis A and generally concentric with the longitudinal central axis of the linear actuator 44. A plurality of spaced-apart bars 50 extend upwards and downwards from of the linear actuator 44 and these correspond to the unison along vertical axes by the actuation of the linear actuator 44. The bars 50 are received non-rotatably in a block 52 of a mixed adjustment mechanism 54, which is supported on a structure 56 in the form of an inverted cup that is secured to the upper surface of the support arm 30, figure 5.

The adjustment mechanism 54 includes an upper plate 58, and the support arm 30 is moved relative to the upper plate 58 along slots 60 spaced apart in the structure 56, which extend generally parallel to the longitudinal axis of the support arm 30 to provide a precisely controllable adjustment of the support arm 30, and due to that of the supply tube 22, in the X direction. To effect such adjustment, an adjustment screw 62, which is threaded in the structure 56a has an inner end which engages the upper plate 58, and the turning movement of the adjustable screw 62 is effective to move the support arm 30 for or backward in the direction of the X relative to the adjustment mechanism 54 , whose position in a horizontal plane is fixed by virtue of the fastening of the linear actuator 44 to the structure 46, as described.

The adjusting mechanism 54 also includes a lower plate 64, and the support arm 30 is moveable relative to the lower plate 64 along opposite, separately spaced slots 66 in the cup-like structure 56, which they extend transversely to the longitudinal axis of the support arm 30, to provide an accurate control adjustment of the support arm 30, and therefore of the supply pipe 22, in the direction of the Y. To effect such adjustment, a screw of setting 68, which is threaded into an extension of the upper plate 58, and has an inner end that meshes with a protruding part 70 of the cup-like structure 56, and by the turns of the adjusting screw 68 the arm moves of support for or backward in the direction of the Y relative to the adjustment mechanism 54. Of course, when the flywheel 42 is held down against the protrusion 70, the support arm 30 will be prevented from friction starting from the movement relative to the adjustment mechanism 54, either in the direction of the X or the Y.

Due to the high ambient temperatures in which the feed tube 22 is used, it is important to cool the support arm 30 from which the feed tube 22 is suspended. For this purpose, an annular passage 72, FIG. provides on the support arm 30 that surrounds and extends generally concentrically to the feed tube 22, and other fluids such as cooling air or other cooling fluids are caused to flow through the passage 72 from the inner and outer lines 74 , and 76 respectively. In addition, a semi-cylindrical head guard 78 is suspended from the support arm 30 and is located by partially surrounding the upper end of the linear actuator 44, and between the linear actuator 44 and the feed tube 22, to delay the heat of the linear actuator 44. by the radiation of the heat from the feeding bowl B.

The flange 24, of FIG. 3, or the feed tube 22, is secured, but releasably, held in engagement with the flange 26 by a plurality of separately spaced circumferentially engaging mechanisms, each generally identified by number 80, of figure 1, three of such hooking mechanisms are shown in figure 2. Each hooking mechanism 80 comprises a lever 82, figure 3, with a steering wheel part 82a with one end thereof and one elongated cam part 82b at the opposite end. The lever 82 is pivotally connected to a support member 84 about an axis C and, when the lever extends vertically, the cam part 82b meshes securely and the upper surface of the clamping ring 86 which engages the flange 24 of the feeding tube 22 for pressing the flange 24 forcefully into the desired operating position, when the lever 82 is pivoted to a horizontal orientation, the cam part 82b stops engaging the ring 86, FIG. 7. In this position, the feeding tube 22 can be removed from the feeding bowl B by a simple lifting movement, using the lifting eyes 18, figures 2 and 14. The latching mechanisms 80 are moveable in alignment with the feeding tube 22 by the support member 84 pivotally connected to the fixed structure 88 about the axis D. In this In this case, the support member 84 is slidable towards an elongated area 88a of the fixed structure 88, where it can then be pivoted about the axis D out of interference relation with the holder 86. Before the installation of a new feed tube 20 , the support arm 30 must be raised so that the new feeding tube 20 does not come into contact with the feeding bowl B.

The pivoting of the support arm 30 around the axis A is carried out when it is desired to replace the feeding bowl B. After the release of the feeding tube 22 from its engaging position by releasing the latching mechanism 80, as described above, and then actuating the linear actuator 44 for lifting the supporting arm 30 to an elevation such that the bottom of the feeding tube 22 is free of the feeding bowl B, the feeding tube 22 is then lifted from the semi-assembly 28. For this purpose, the upper plate 58 of the adjusting mechanism 54 is pivoted with respect to the plate lower 64, after removing an alignment latch 114 aligning circumferentially with the top plate 58, the bottom plate 64 and the block 52 relative to one another during the operation of the feed tube assembly 20.

The linear actuator 44 is operated by a servo motor AC alternating current (AC), which is connected coaxially with the actuator 44, although it is contemplated that the connection can be parallel to the axes with a V belt. or other means of transmission extension between them. In any case, an assembly that includes actuator 44 and servo motor 90 is available from E-Drive Desing of Glastonruty, CT, as described hereinabove. As shown in FIG. 8, the motor 90 has a hollow projecting arrow 92. The hollow projecting arrow 92 of the motor 90 is slid on an inner arrow 94 of the linear actuator 44.

(Figures 8 and 11), which has an internal ball screw 96. The internal ball thread transfers the rotational movement of the arrow 92 to the linear movement of an annular member 98, either for or backward depending on the direction of rotation of the arrow 92.

The annular member 98 can be manually positioned by rotating a lever 102, which is fixed to the arrow 92. The arrow 92 extends to a level that is below the engine 90, currently below the level of an arched shield 100 for the heat that protects the motor 90 from thermal radiation coming from the feed bowl B, and the lever 102 extends it outwardly from the arrow 92. The lever 102 has a flywheel projecting downwards therefrom, to a location radially towards outside the arrow 92, and the arrow 92 can be turned by manual gearing of the steering wheel 104 and the use of this to rotate the lever 102.

The motor 90 is provided with an annular brake 106 which rotates with the arrow 92, and the brake 106 is selectively engaged by a double-ended tightening band 108. The band 108, when in a non-constrictive mode, does not engage the brake 106 and provides in such a way a non-braking effect. However, the band 108 can be selectively adjusted by the actuation of a pneumatic cylinder 110 acting through an articulated system 112, and, when the cylinder 110 is removed, as shown in Figure 12, the band 108 will be tight so that it engages the brake 106. Thus the rotation action of the arrows 92, 94 is retarded, and therefore it secures the platform 30 at a desired elevation.

The linear actuator 44 requires a constant lubrication in service, and for this purpose there are a plurality of internal oil lubrication lines 116, 118, 120, 122, 124, 126, and 128 (Figure 4) to provide lubricating oil from a common source (not shown) for several points of the linear actuator 44. These points include the entries 130,132 (FIG. 11) of the cylinder 44a of the linear actuator 44 of each of the four (4) bars 50 (FIG. 6) that extend to from this. The lubrication oil is collected at the bottom of the cylinder 44a and returned to the source to be recirculated, via a return line 134 (Fig. 4) preferably after being filtered and cooled if necessary, with a supply of fresh oil that It is provided for any loss of oil in the system. The lubrication system, as described, is a closed system that provides adequate lubrication for moving surfaces while simultaneously minimizing lubricant losses in a hot and relatively inaccessible environment and serves to preserve a product derived from natural products that are expensive and irreplaceable.

In Figure 13 and 14 the elements that differ from, but correspond to, elements of the modality of Figure 1-12 are identified by the 200 series of reference numbers, the last two digits of which are the two digits of the corresponding element of the modality of figures 1-12. Figure 13 illustrates a latching mechanism 280, and three such latch mechanisms 280 are illustrated in Figure 14 in a spaced apart relationship. Each latch mechanism 280 comprises a lever 282 with a handwheel portion 282a at one end thereof and an enlarged cam portion 282b at an opposite end of the handwheel portion extending from a position that is between the ends of the cam portion 282b considering that the flywheel portion 82a of the lever 80 of the mode 7 aligns with one end of the cam portion 82b. With respect to this, the cam portion 282b of the lever 282 has a contour that is more universally requested than several installations having contours having the cam part contour 82b of the lever 82 due to variations in the thickness of part of the lever. the flange 24 of the feeding tube 22 from installation to installation. The lever 282 is pivotally connected to a support member 84 about an axis and when the lever extends vertically, the cam part 282b surely engages a hollow bottom in a notch or cut 286a of a clamping ring 286, which engages to the flange 24 of the feed tube 22 to strongly press the flange 24 into its desired operating position. The use of the notch 286a in the clamping ring 286 facilitates better engagement of the ring 286 by the cam portion 282b of the lever 282, and this further facilitates easier release of the clamping action of the lever 280 when desired changing to the feeding tube 22 when the lever 282 is pivoted to a horizontal orientation, the cam part 282b ceases to engage the clamping ring 286. In this position, the clamping ring 286 can be raised from its position, as shown in the shadow of the phantom part of figure 14, so that it is allowed to raise the feed tube 22 from its position, it being necessary to move each of the hooking mechanisms 280 out of which they interfere with the alignment of the ring. 286 and the feeding tube 22. This is obtained by sliding the support member 84 towards the elongated area 88a of the fixed structure 88 and then by pivoting the support member. support 84 around the axis D without there being an interference relationship with the fastening ring 286. Although the best mode contemplated by the inventor to carry out the present invention as the date of presentation thereof which has been shown and described herein, it will be apparent to those skilled in the art that appropriate modifications, variations, and equivalents can be made starting from the scope of the invention, such scope is limited only by the terms of the following claims and the equivalents thereof. It is noted that in relation to this date, the best method known to the applicant, to carry out the aforementioned invention is that it is clear from the manufacture of the objects to which it refers.

Claims (21)

1. A feeding tube assembly for a feeding bowl of a forehearth of a furnace for glass melting, said feed tube assembly is characterized in that it comprises: an elongated mounting arm that extends generally horizontally and has a pair of opposite ends; a feeding tube that usually extends vertically; means supported by means of a support for the releasable securing of said feeding tube to said support arm in a location adjacent to one end of said support arm; a linear actuator operated by a servo motor that extends generally vertically and which supports said support arm at a location between said opposite ends, said linear actuator operated by a servo motor and operable to adjust the elevation of said support arm .

2- A feeding tube assembly according to claim 1, characterized in that it also comprises; means supported by said support arm to rotate said feeding tube in relation to said support arm about a longitudinal central axis of said feeding tube.

3. A feeding tube assembly according to claim 1, characterized in that: said support arm has an opening placed between its opposite ends, said opening is vertically aligned with a longitudinal central axis of said linear actuator, said support arm is rotatable with respect to said linear actuator about said longitudinal central axis of said linear actuator .

4. A feeding tube assembly according to claim 3, characterized in that it additionally comprises; means for adjusting the position of said support arm in relation to said linear actuator along a longitudinally extending axis of said support arm.

5. A feeding tube assembly according to claim 4, characterized in that it additionally comprises; means for adjusting the position of said support arm in relation to said linear actuator along a transversely extending axis of said support arm.

6. A feed tube assembly according to claim 1, characterized in that; said linear actuator operated by a servo motor that extends generally vertically comprises a ball screw mechanism for a rotary translation movement of an outer arrow of said servo motor to linear movement.

7. A feeding tube assembly according to claim 6, characterized in that; said linear actuator operated by a servo motor that extends generally vertically additionally comprises means for a releasable braking of said servo motor against rotation.

8. A feed tube assembly according to claim 1, characterized in that; said support arm has a second opening, said second opening of said support arm is vertically aligned with said feeding tube, and additionally comprises; means for cooling said support arm in an annular contour in a location adjacent to said second opening.

9. A feed tube assembly according to claim 6, characterized in that said linear actuator has a housing and a member at least partially contained within said housing and is movable with respect to said housing between first and second positions as a result of the rotation movement of said arrow of said servo motor, and additionally comprises; a fixed support structure, said housing is secured and fixed to said support structure.

10. A feed tube assembly according to claim 9, characterized in that said linear actuator further comprises; a block; a plurality of spaced apart bars extending from said member -of said linear actuator of said block; and means for tightening said support arm relative to said block to prevent rotation of said support arm in relation to said linear actuator.

11. A feed tube assembly according to claim 9, characterized in that said linear actuator has an internal arrow, said internal arrow of said linear actuator is integral with said external arrow of said servo motor, and further comprises; means for rotating said internal arrow of said linear actuator and said external arrow of said servo motor independently of the operation of said servo motor.

12. A feeding tube assembly according to claim 2, characterized in that said means of rotation of said feeding tube comprises; a toothed ring assembly positioned generally concentrically with respect to said feed tube, said toothed ring is not rotatable with respect to said feed tube; a toothed pinion meshes said toothed ring; and with this rotary movement is provided to said toothed pinion.

13. A feeding tube assembly according to claim 1, characterized in that it additionally comprises; a closed means of circulation of lubricating oil for a continuous lubrication of said linear actuator operated by a servo motor.

14. The method for replacing a feeding bowl of a forehearth installation of a glass melting furnace, the feeding bowl has a position installed in the installation, the installation has a feeding tube assembly with an elongated support arm extended generally horizontally and a rotary feeding tube secured to one end of the support arm and normally placed with a lower end submerged in the feeding bowl, the method is characterized in that it comprises; raise the support arm to the lower end of the feed tube that is higher than the feed bowl; pivoting the support arm about an axis spaced from the feed tube until the feed tube is not in vertical alignment with the feed bowl; Y then lift the feeding bowl from its installation position without otherwise removing the support arm.

15. A latching mechanism for the releasable securing of a fastening ring to a flange of a supply pipe in an installation of a forehearth of an oven in the glass melting, said latching mechanism is characterized in that it comprises; a lever having a steering wheel part and a cam part with a rounded cam surface, said steering wheel part extending outwardly from said cam part from said rounded cam surface; a support member, said lever is pivotally connected to said support member at a location near one end of said support member; Y a fixed member, said support member is pivotally connected near an opposite end of said support member, to said fixed member; - the pivoting of said support member with respect to said fixed member is effected to rotate said lever of the interference contact with the clamping ring to allow the clamping ring to rise from the engagement with the. flange of the feeding tube.

16. A latching mechanism according to claim 15, characterized in that said steering wheel part extends outwards from said cam part at a location on the end of said cam part.

17. A latching mechanism according to claim 15, characterized in that said steering wheel part extends inwardly from said cam part at a location between the ends of said cam part.

18. In combination with a clamping ring of a type used for the engagement of a flange of a feed tube in a forehearth installation of a furnace for glass melting, said clamping ring has a top surface, a latching mechanism for the releasable engagement of said upper surface of said clamping ring, said latching mechanism is characterized in that it comprises: a lever having a hand-wheel part and a cam part with a round cam surface, said hand-wheel part extending outwardly from said cam part from said rounded cam surface; a support member, said lever is pivotally connected to said support member at a location near one end of said support member, and a fixed member, said fixed member is pivotally connected to said support member, at a location near an opposite end of said support member, to said fixed member; the pivoting of said support member with respect to said fixed member is effected to rotate said lever from an interference contact with the clamping ring to allow the clamping ring to rise out of engagement with the flange of the feed tube.

19. A combination according to claim 18, characterized in that said clamping ring has a notch that is engaged by said rounded cam surface of said lever when said lever is engaged and fastened to said clamping ring.

20. A combination according to claim 19, characterized in that said steering wheel part extends outwardly from said cam part at a location between the ends of said cam part.

21. A combination according to claim 18, characterized in that said flywheel portion extends outwardly from said part as a flywheel at a location at one end of said cam part. SUMMARY OF THE INVENTION A feed tube assembly for a feed bowl of a forehearth oven for glass melting. The feed tube assembly has an elongated support arm that extends horizontally, and a feed tube that is supported by a support arm to a location near one end of the support arm. The feed tube is rotatable about its longitudinal central axis with respect to the support arm, and the support arm supports steering elements for rotation of the feed tube about its longitudinal central axis. The support arm is supported on a linear actuator operated by a servo motor that extends vertically, and the lift of the support arm is adjusted by the actuation of the linear actuator, a releasable brake is provided for the prevention of rotation of the servo motor when it is desired to prevent a change in the lifting of the support arm. The position of the relative support arm with the linear actuator is independently adjustable in both cases, by the support arm longitudinally and by the support arm transversely, and the support arm is rotary with respect to the linear actuator when it is desired to replace a tube of food supported by means of this or the feeding bowl directly below it.