GB2042500A - Apparatus for extracting molten glass from the tap hole of a tank and for transporting the glass to a fabrication station - Google Patents

Abstract

An apparatus for the extraction of molten glass from a tank and for transporting the glass to a fabrication station, which apparatus comprises a rotating rod adapted to be introduced through the tap hole of the melting furnace and by its free end into the molten glass, and is mechanically movable. In order to achieve a space-saving construction but nevertheless considerable flexibility in adaptation to different fabricating machines with relatively high working speeds, the drive device is disposed in a substantially stationary position higher than the tap hole and is directly above the fabrication station, and the rod is axially displaceable in a vertical plane relative to the drive device and swivellable about a horizontal transverse axis, the axial displacement and the swiveling being controllable independently of one another. <IMAGE>

Description

SPECIFICATION Apparatus for extracting molten glass from the tap hole of a tank and for transporting the glass to a fabrication station The present invention relates to an apparatus for extracting molten glass from a tank or the like and for transporting the glass to a fabrication station.

One known form of apparatus of this type comprises a rod which is rotatable about its axis. The rod is moved through the tap hole of the glass furnace, and its free front end is introduced to the molten glass. With the aid of a drive device the rod can be removed substantially axially from the tap hole and swivelled so that its free end carrying the molten glass is above the fabrication station.

In one particular apparatus of this kind (DE-AS 2,031,054) the rod gathering the glass on its free end is mounted on a carriage which travels on a frame, which is mounted on the floor in front of the tape hole, approximately in a direction at right angles to the furnace wall, that is to say in the longitudinal direction of the rod dipping into the glass. Constrained guide means for the carriage are disposed on this frame in such a manner that the rod first moves out of the tap hole of the furnace in the longitudinal direction and is then swung laterally to a position above the fabrication station. The swivelling movement is coupled by constraint to the longitudinal displacement of the carriage carrying the rod.

An apparatus of this kind has some shortcomings.

Firstly, it must be borne in mind that usually only limited space is available around a glass tank or the like. In order to be able to use the tank economically, however, as many tap holes are possible should be in operation, that is to say as many fabricating machines (for example presses provided with a rotating table) as possible should be fed simultaneously. The space available is, in the first place, already considerably reduced with the known apparatus by the relatively large frames for the carriage carrying the rod. Moreover, each of the fabricating machines must be disposed at the side of the frame, so that there is a danger that a fabricating machine will already project into the region of the neighbouring tape hole, where there will consequently be no room to accommodate the necessary frame for another gathering device.As a result, when the known apparatus is used only relatively few fabricat ing machines can be disposed at the same time around a glass furnace. In no case is it possible to provide the same number of fabrication stations as would be possible with manual gathering of the glass from the furnace, although of course manual gathering is undesirable from the point of view of economic production.

Another drawback of the known apparatus is that the carriage carrying the rotating rod must travel over a relatively long displacement path for the complete axial and rotary movement of the rod, so that the cycle times for the gathering of the glass obviously become correspondingly long. Furthermore, difficulties may also arise in respect of the selection of the correct drive for the displacement movement, since for example pneumatic or hydraulic cylinders frequently do not have a sufficiently long stroke, so that a combination of a number of cylinders must be provided to obtain the complete displacement movement of the carriage.

Finally, an extremely serious drawback of the known apparatus is to be seen in the fact that only a single movement of the rotating rod, or of its free end, is possible in practice, since the conversion of the axial displacement of the rod into a swivelling movement is effected with the aid of a fixed guide, which usually cannot be changed or can be changed only with great difficulty. Consequently, the known apparatus can generally be used only in conjunction with one particular fabricating machine. Conversion to another fabricating machine, and also conversion to different heights of moulds on the rotating table of one and the same fabricating machine, gives rise to difficulties with the known apparatus.Machine feeding of moulds for elongated glass objects, for example long cake dishes, is not possible with the known apparatus, because the necessary linear discharge of the molten glass is not possible, or possible only with very great difficulty.

The problem underlying the invention is now that of providing an apparatus which reduces as little as possible the limited space available around a glass furnace, which nevertheless permits considerable flexibility with regard to adaptation to different fabricating machines, and finally also allows working at relatively high speeds.

According to the invention there is provided apparatus for extracting molten glass from the tap hole of a tank, and for transporting the glass to a fabrication station, said apparatus comprising a drive device disposed in a substantially stationary position at a height at least as high as the tape hole; a rotatable rod mounted on said drive device and having a free end remote from said drive device; an actuator to displace said rod axially relative to the drive device, whereby the free end can be passed through said tape hole into the molten glass in said tank; a rotational drive to rotate said rod about its longitudinal axis; and means to swivel said rod about a substantially horizontal axis, which is transverse to the axis of the tap hole and directly above the fabrication station, the actuator and the means to swivel the rod being controllable independently of one another.

In contrast to the procedure hitherto customary, in the apparatus according to the invention the drive for the rotatable rod is not now mounted on the floor in the region in front of the tap hole, but is mounted atin a suitable height above the fabrication station.

This provides the very important advantage that the space around the glass furnace, which is already very limited, is not encumbered by the drive device for the gathering rod. Furthermore, unlike the previous arrangement, the rod is moved in a vertical plane, so that the fabricating machine can be placed directly in front of the tap hole and consequently the distance between neighbouring tap holes can be correspondingly short.The special type of movement of the rotatable rod also brings the advantage that only relatively short axial movement paths are required for the rod and that the vertical swivelling movement can be restricted to a relatively small angle, usually of less than 90". It is thus possible to obtain relatively short movement times for bringing the free end of the rod out of the mass of glass into the position above the fabrication station, which is very advantageous particularly when using fabricating machines having a rotating table having a relatively large number of working positions.When it is swivelling out of the position in which it is moved out of the tap hole into the position above the fabrication station, the rod is situated in the retracted position, so that the swivelling radius between the centre of rotation of the rod and its free end is relatively short. Consequently the centrifugal forces acting are correspondingly small, and the swivelling movement can therefore also be made at adequately high speed.Since in addition the axial displacement and the swivelling are effected through separate drives, that is to say are controllable independently of one another, suitable programming will enable almost any desired movement of the free end of the rod, carrying the molten glass, to be achieved, so that for example the movement by which the free end of the rod is dipped into the molten glass can be selected in accordance with the wishes of the user, that is to say either in the longitudinal direction of the rod or with the aid of a transverse movement, so that the angle of insertion into the molten glass can be suitably selected. Moreover, selection of the swivelling angle enables a certain adaptation to be achieved when the fabrication station is inaccurately positioned.

The desired movements of the rotatable rod can advantageously be achieved with a drive device comprising a main frame, a base swivellable about the horizontal transverse axis, relative to the main frame and a carraige carrying the rotatable rod together with said rotational drive, said carriage being mounted on said base for movement in the axial direction ofthe rod.

The carriage need not be of too expensive construction, since its axial movement need only be a distance corresponding to the path of movement of the free end of the rotatable rod from the glass mass to the outer edge of the tap hole. The remainder of the movement of the rod is the swivelling movement in the vertical plane, while without great difficulty it can be ensured that the free end of the rotatable rod will in all cases reach a position lying above the fabrication station. The drive device must for this purpose simply be disposed at a suitable height. The carriage is expediently constructed of two pillars axially displaceable in bearings in the base and fastened together at their front end by a crossmember, which carries the rod so that the latter is rotatable but not slidable and which is acted on for the axial movement by an actuator mounted on the base.

In a construction of this kind it has been found advantageous for the pillars, the cross-member, and preferably also the rod to be provided, at least over a part of their length, with coolant ducts in such a manner that a coolant circuit is formed which starts in the rear end of one pillar and ends at the rear end of the other pillar. The connection between the ducts in the cross-member and the rotatable rod must then of course be made with the aid of a suitable rotary joint. When a coolant circuit of this kind is provided the advantage is gained that the temperature of the carriage and of the rod can be suitably restricted, so that no difficulties in respect of possible variations of dimensions or the like need be feared, while in addition the life of the apparatus can be lengthened.

Advantageously, the drive device is displaceable horizontally parallel to the axis of the tap hole, whereby a corresponding adaptation of the gathering device to the fabrication station is made possible.

If according to the invention the drive device in this arrangement is displaceable with the aid of its own positioner, in a direction parallel to the axis of the tap hole, moulds for elongated glass objects, for example long cake dishes, can also be filled in a simple manner. For this purpose it is of course necessaryforthe molten glass mass to be deposited in the form of an elongate piece, which can be achieved by displacing the entire drive device horizontally by means of its own positioner, when the free end of the rotatable rod is situated in the discharge position above the fabrication station.

If in addition the drive device is adjustable transversely to the direction in which the positioner acts, additional adjustment will be possible for accurate adaptation to the fabrication station.

The horizontal adjustability of the entire drive device can be achieved in a simple manner if the drive device comprises a bearing support and upper and lower guide pillars upon which said main frame is slidably mounted.

The axial displacement of the rotatable rod, and optionally the horizontal displacement of the drive device, can be achieved with different drive means.

Having regard to the relatively short movement paths and the desired considerable freedom in the control of the movement, it is however advantageous to use a hydraulic or pneumatic cylinder as actuator for the axial displacement of the rotatable rod and optionally as positionerforthe horizontal displacement of the drive device.

The swiveller of the carriage relative to the main frame is generally effected with the aid of an electric or hydraulic motor. It is then essential that the position in which the free end ofthe rod is dipped into the molten glass mass should be accurately defined, for which purpose an adjustable stop may be provided for the rotatable rod moved forward in the position in which its front end dips into the molten glass. This stop advantageously cooperates with the carriage carrying the rotatable rod, preferably with the cross-member, in the forward position.

This stop may be a spindle preferably disposed on the bracket and adjustable in the swivelling direction of the rod. In this case the adjustability of the spindle makes it possible to make an additional adjustment in dependence of the level of molten glass at any particular moment.

In principle the apparatus of the invention can be used in all kinds of glass melting furnaces, particu larly in tank furnaces. In tank furnaces it very often happens that the molten glass in the furnace is kept in movement by means of a rotor rotating about a vertical axis. This leads to a certain formation of waves in the glass mass, with a corresponding variation of the level of the glass. In order to achieve good results it is however desirable that the depth of penetration of the free end of the rotatable rod should always be exactly the same, that is to say the level of glass should always as far as possible be the same.

According to another aspect of the invention there is provided glass handling apparatus comprising a tank for molten glass; a rotor rotatable about a vertical axis within the molten glass in said tank; a tap hole in the side of said tank; a drive device disposed in a substantially stationary position at a height at least as high as the tap hole; a rotatable rod mounted on said drive device and having a free end remote from said drive device; an actuator to displace said rod axially relative to the drive device, whereby the free end can be passed through said tap hole into the molten glass in said tank; a rotational drive to rotate said rod about its longitudinal axis; means to swivel said rod about a substantially horizontal axis, which is transverse to the axis of the tap hole, and directly above the fabrication station, the actuator and means to swivel the rod being controllable independently of one another; and means for synchronizing the actuator and/or swivel means, so that the free end of the rotatable rod avoids contact with said rotor.

Such an apparatus makes it possible to comply with the above requirement.

The free end of the rotatable rod may be of various types. It is however advantageous for the rotatable rod to carry at its free front end, in a manner known per se, a ball-like end piece, which advantageously should be interchangeable. In this case the possibility exists of using end pieces of different shapes, and in particular of different diameters, thus making it possible for different amounts of glass to be gathered in accordance with the requirements of the fabrication station.

If a heat insulating screen is provided between the drive device and the tap hole of the furnace, the drive device can to a considerable extent be protected against the effects of radiation through the tap hole, and thus the life of the apparatus may possibly be greatly lengthened. The installation of a screen of this kind will not give rise to very great difficulty, since it could for example be fastened to the cross-member of the carriage.

Other features, details and advantages of the invention will emerge from the following description of a preferred embodiment, which is illustrated in the drawings, in which the sole Figure shows diagrammatically the tap hole region of a glass tank furnace together with the apparatus according to the invention.

In the furnace a tank 1 contains a molten glass pool 2. The tank 1 is separated by a wall 3 from the working area floor 4 surrounding the furnace, while access to the molten glass 2 in the tank 1 is possible through tap holes 5 in the wall 3. As is generally customary, the surface 2' of the molten glass 2 is about 1.20 to 1.40 metre above the floor 4.

On the floor 4 are installed fabricating machines, for example a glass press 6, which is indicated -in dash-dot lines in the drawing and which has a rotating table 7, on which moulds 8 are disposed.

Above the fabrication station, represented by the mould 8, shears 9, represented only diagrammatically in the drawing, are also provided.

The problem now arises of extracting molten glass mass from the tank 1 through the tap holes 5 by means of a rotatable rod, in the manner known from manual working practice, and carrying this glass to the fabrication station 8 via the shears 9. For this purpose a driving device, given the general reference 10, is provided for the rotatable rod 11, which carries at its free end a substantially spherical end piece 12, which is interchangeably mounted and which is adapted to be dipped into the glass pool 2.

As can clearly be seen in the drawing, according to the invention the drive device 10 is mounted substantially overhead, that is to say at a height of at least about 1.90 metre, on an arm 13 of a bracket 14, and lies at a greater height than the tap hole 5 or in the top region of the latter, so that it is possible for the rotatable rod 11, pointing slightly obliquely downwards (shown in solid lines in the drawing), to project through the tap hole 5 into the tank furnace and to dip into the glass pool 2. The arm 13 of the bracket 14 also extends exactly over the region of the fabrication station 8.

The drive device 10 for the rotatable rod 11 comprises on the one hand a carriage 15 which is displaceable axially in the'longitudinal direction of the rod 11 and which is composed essentially of two pillars 17 axially displaceable in bearings on a base 16 and fastened together by means of a crossmember 18, on which the rod 11 is mounted rotatably. In the region of the cross-member 18 a rotary drive 19 for the rod 11, for example a hydraulic motor, may also be disposed, this drive 19 being knownperse.

The actuator 20 for the axial displacement of the carriage 15, consisting of the cross-member 18 and the two pillars 17, and henceforthe axial displacement of the rotatable rod 11, comprises a hydraulic or pneumatic cylinder 20, which is mounted on the base 16 and whose piston rod 21 acts on the cross-member 18 of the carriage 15.

The base 16 is in turn mounted on a main frame 22 for swivelling about the horizontal axis 23 by means of a suitable rotary drive, for example an electric motor or hydraulic motor, so that the carriage 15 and hence the rotatable rod 11 can also swivel in a vertical plane about the axis 23.

Finally, the main frame 22 is fastened by means of a bearing support 24 to the arm 13 of the bracket 14.

The bearing support 24 comprises upper and lower horizontal guide pillars 25, the main frame 22 being displaceable along pillars 25 in a horizontal direction substantially parallel to the vertical plane of movement for the rotatable rod 11.This horizontal displacement of the main frame 22 can be achieved automatically by means of a positioner 26, which for example may likewise be a hydraulic or pneumatic cylinder, which is mounted on the bearing support 24 and by means of its piston rod 27 acts on the main frame 22.

The bearing support 24 is in addition expediently mounted on the arm 13 of the bracket 14 for displacement horizontally in a direction extending transversely to the lateral plane, while for example suitable slots or the like may be provided to receive fastening bolts. This transverse displacement need however be possible only for the first adjustment of the drive device 10 relative to the fabrication station 8, so that an actuator is not required for this purpose, although of course one could be provided.

Another feature of the drive device 10 according to the invention is that the pillar 17 and the crossmember 18 of the carriage 15 are provided with coolant ducts (not shown). Corresponding coolant ducts can also be provided over at least part of the length of the rotatable rod 11, in which case provision must then be made in a suitable manner knownperseforthe connection of the coolant ducts in the cross member 18 and rod 11, even during the rotary movement of the latter. These coolant ducts form a coolant circuit which begins at the rear end 28 of one of the pillars 17 and ends at the rear end 29 of the other pillar 17. At these ends a coolant, for example water, can be introduced and discharged respectively, for example through hoses 30, so that it is possible for the temperature of the rotatable rod 11 and of the carriage 15 to be kept suitably low.

On the bracket 14 is also provided a stop 32 which is formed by an adjustable spindle 31 and with which the cross-member 18 of the carriage 15 cooperates in the advanced position of the carriage 15 shown in the drawing; when the cross-member 18 lies against the stop 32 the end piece 12 of the rotatable rod 11 is in the correct position for gathering molten glass from the glass pool 2.

The mode of operation of the apparatus according to the invention is now as follows: By suitable adjustment of the axial position of the carriage 15 and of the angular position ofthe base 16 relative to the main frame 22, the rod 11 is brought into the position shown in solid lines in the drawing, in which the end piece rotating with the rod 11 gathers molten glass from the glass pool 2.

After a determined period of time, which is sufficient for the gathering of the amount of glass needed, the rotary drive for the base 16 is then put into operation and the base 16, together with the carriage 15, is swivelled through the angle a in the counterclockwise direction, so that the rod 11 together with the end piece 12 is moved upwards in the direction of the arrow 33 into the position 34.

Either in the course of this angular movement of the base 16 or after the position 34 has been reached the actuator 20 is brought into action and the carriage 15 is moved axially in the direction of the arrow 35, so that the end piece 12 comes into the position 36. The carriage is then swivelled clockwise in the direction of the arrow 38, with the end piece following path 37, through the angle a + P, that is to say until the rod 11 points roughly vertically downwards. The adjustment of the drive device 10 must be such that the end piece 12 will normally be situated exactly above the fabrication station. If in this position the end piece 12 should be too far from the shears 9, the actuator 20 is operated again and the carriage 15, together with the rod 11 and the end piece 12, is lowered a suitable distance in the direction of the arrow 39.

In this position there is a pause in the movement, until the molten glass has flowed off the end piece 12 and been cut off by means of the shears 9.

Thereupon, if necessary after renewed operation of the actuator 20 and lifting of the carriage 15 in the opposite direction to that of the arrow 39, the rotary drive is put into operation once more and the base 16, together with the carriage 15 carrying the rod 11, is swivelled upwards in the countercloskwise direction (arrow 38') either only through the angle or optionally through the angle a + , so that the end piece 12 will be either in the position 40 or in the position 36. This swivelling movement is possible despite the presence of the stop 32, since during the swivelling movement the carriage 15 is of course in the retracted position.

The actuator 20 for the carriage 15 is then operated again to move the said carriage together with the rod 11 forwards, so that the end piece 12 is brought either into the position 34, in cases where it had previously been swivelled through the angle a + P, or directly into the dipped position shown in the drawing when it was swivelled only through.the angle p. If the swivelling movement was the larger one and the end piece 12 assumes the position 34, the rotary drive for the base 16 can then be operated again to move the end piece 12 clockwise in the direction of the arrow 33', so as to dip the end piece 12 into the glass pool 2.

Starting from this position, in which the molten glass is gathered, the above described cycle of movements then takes place again. In the gathering of the glass from the glass pool 2 it is essential that the cross-member 18 should lie correctly against the suitably adjusted stop 32, so that the end piece 12 will be accurately adjusted relative to the surface 2' of the glass pool 2.

If with the apparatus according to the invention it is desired to fill with glass an elongated mould, for example a mould for making long cake dishes, it will in addition be necessary to make use of the movability of the main frame 22 relative to the bearing support 24. In this case, when the glass is extracted from the glass pool 2 the main frame 22 will normally be in an end position, for example lying against the bearing support 24 on the right in the drawing. As soon as the end piece 12 has reached the discharge position 41, the positioner 26 is operated and thus the main frame 22 is moved in the direction of the arrow 42 (to the left), so that a strand of glass is deposited in the mould. After the left-hand end position has been reached, the shears 9 can then be operated. It is however also possible to operate the positioner 26 again to move the main frame 22 in the opposite direction, that is to say in the direction of the arrow 42', as far as the end position and only then to operate the shears 9. As soon as the shears 9 have been operated, the return movement of the end piece 12 to the gathering position is started, while, where applicable, the displacement of the main frame 22 relative to the bearing support 24 must take place, simultaneously with the rotary movement of the base 16, in the course of this return movement.

It has already been mentioned that, particularly in tank furnaces, a rotor (not shown in the drawing) is provided, which keeps the glass pool 2 in movement and leads to the formation of waves in the region of the surface 2' of the glass pool 2. The problem then arises that the height of the glass surface 2' varies in dependence on the position of the rotor, so that the depth of penetration of the end piece 12 would normally also vary, thus leading to the gathering of varying amounts of glass.

In order to obviate this difficulty, two solutions are possible. The first consists in initiating each dipping movement of the rod 11 and end piece 12 into the glass pool 2 in dependence on the position of the rotor. Since a clearly defined time is required for the dipping movement, it can in this way be ensured that reproducible conditions exist for each dipping operation.

Another possible solution consists in varying the position of the stop 32 in dependence on the height of the glass surface 2' at any given moment, for example with the aid of a suitable motor, which is possible because the speeds of rotation of the rotors in glass tanks are only relatively low. In both cases it is necessary to provide a transmitter, which is operated by the rotor and which either initiates the dipping movement of the rod 11 together with the end piece or controls the adjustment of the stop 32.

Finally, it should also be pointed out that it would be possible to provide the apparatus with a heat insulating screen to shield the apparatus from the tap hole and thus prevent excessive action of heat from the molten glass mass 2 on the apparatus or parts of the latter. A screen of this kind could for example be in the shape of part of a circle and be mounted on the carriage 15, in which case it would move axially with the carriage. In addition, it would of course also be possible to mount the screen on the base 16, in which case it would participate in the swivelling movement but not in the axial movement of the carriage 15.

In the drawing it can clearly be seen that in the swivelling movement of the end piece 12, for example from the position 36 into the position 41, the swivelling radius is only relatively short, for example less than 1 metre, so that even with relatively high swivelling speeds only slight centrifugal forces occur. Similarly, the carriage 15 with the rotatable rod 11 has to be moved axially only over considerably shorter distances than in the prior art.

Normally it is sufficient for the carriage 15 together with the rod 11 to be able to move axially a distance of 0.8 metre. Because of these circumstances, very rapid working is possible. Moreover, it is possible without difficulty to use a customary fabricating machine in which the shears are usually disposed at a height of about 1.2 metre.

Claims (21)

1. Apparatus for extracting molten glass from the tap hole of a tank, and for transporting the glass to a fabrication station, said apparatus comprising a drive device disposed in a substantially stationary position at a height at least as high as the tap hole; a rotatable rod mounted on said drive device and having a free end remote from said drive device; an actuator to displace said rod axially relative to the drive device, whereby the free end can be passed through said tap hole into the molten glass in said tank; a rotational drive to rotate said rod about its longitudinal axis; and means to swivel said rod about a substantially horizontal axis, which is transverse to the axis of the tap hole and directly above the fabrication station, the actuator and the means to swivel the rod being controllable independently of one another.

2. Apparatus according to claim 1, wherein said drive device comprises a main frame, a base swivellable about the horizontal transverse axis, relative to the main frame and a carriage carrying the rotatable rod together with said rotational drive, said carriage being mounted on said base for movement in the axial direction of the rod.

3. Apparatus according to claim 2, wherein the actuator is mounted on the base and the base further comprises two pillars axially displaceable in said bearings and a cross member fastening said pillars together at their front end, wherein said cross member carries the rod, so that the latter is rotatable, but not slidable, and wherein the cross member is acted on for the axial movement by said actuator.

4. Apparatus according to claim 3, wherein coolant ducts are provided in said pillars and said cross member, whereby a coolant circuit is formed which starts at the rear end of one pillar and ends at the rear end of the other pillar.

5. Apparatus according to claim 2,3 or 4, wherein said drive device comprises a bearing support and upper and lower guide pillars upon which said main frame is slidably mounted.

6. Apparatus according to any preceding claim, wherein the drive device is displaceable horizontally parallel to the axis of the tap hole.

7. Apparatus according to any preceding claim, wherein a positioner displaces the drive device in a direction parallel to the axis of the tap hole.

8. Apparatus according to claim 7, wherein means are provided to adjust the drive device transversely to the direction in which the positioner acts.

9. Apparatus according to claim 6,7 or 8, wherein said positioner is a hydraulic or pneumatic cylinder.

10. Apparatus according to any preceding claim, wherein said actuator comprises a hydraulic or pneumatic cylinder.

11. Apparatus according to claim 1 and further comprising an adjustable stop positioned to locate said rotatable rod, when in its forward position in which its front end dips into the molten glass pool.

12. Apparatus according to claim 2 and 11, wherein the adjustable stop is positioned to locate said carriage, when the latter is in its forward position, in which the front end of a rotatable rod dips into the molten glass pool.

13. Apparatus as claimed in claim 11 or 12, wherein said stop comprises a threaded spindle adjustable in the swivelling direction of the rod.

14. Apparatus according to any preceding claim, wherein a ball-like piece is provided at the free end of the rotatable rod.

15. Apparatus according to claim 14, wherein said ball-like end piece is mounted interchangeably on the free front end of the rotatable rod.

16. Apparatus according to any preceding claim, wherein a heat insulating screen is provided between the drive device and the tap hole of the furnace.

17. Glass handling apparatus comprising a tank for molten glass; a rotor rotatable about a vertical axis within the molten glass in said tank; a tap hole in the side of said tank; a drive device disposed in a substantially stationary position at a height at least as high as the tap hole; a rotatable rod mounted on said drive device and having a free end remote from said drive device; an actuator to displace said rod axially relative to the drive device, whereby the free end can be passed through said tap hole into the molten glass in said tank; a rotational drive to rotate said rod about its longitudinal axis; means to swivel said rod about a substantially horizontal axis, which is transverse to the axis of the tap hole, and directly above the fabrication station, the actuator and means to swivel the rod being controllable independently of one another; and means for synchronizing the actuator and/or swivel means, so that the free end of the rotatable rod avoids contact with said rotor.

18. Apparatus according to claim 17, wherein said synchronizing means includes a transmitter operated by the rotor and initiating the swivelling movement of the rod.

19. Apparatus according to claim 18, wherein an adjustable stop is positioned to locate said rotatable rod when in its forward position, in which its front end dips into the molten glass pool, and wherein said stop is automatically adjustable in dependence on the rotary position of the rotor.

20. Glass handling apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

21. Apparatus for extracting molten glass from the tap hole of a tank, and for transporting the glass to a fabrication station, said apparatus being substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.