METHOD AND DEVICE FOR DISCHARGING CONTROLLED QUANTITIES OF MOLTEN GLASS

Abstract: A device for discharging controlled quantities of molten glass from a discharge reservoir (1) provided with at least one discharge orifice (2) in which at least one vertically movable discharge plunger (3) is arranged in the discharge reservoir (1). There is further arranged in the discharge reservoir (1) coaxially with the centre of the or each discharge orifice (2) a pin (5) which is movable towards and away from the or the respective orifice and is disposed opposite the orifice and by which the orifice (2) can be closed to a variable extent.

Description: Device for discharging controlled quantities of miten glass. The invention relates to a device for discharging controlled quantities of molten glass from a discharge reservoir provided with at least one discharge orifice, at least one vertically movable discharge plunger being arranged in the discharge reservoir. A device of the kind to which the present invention relates is described in DE-PS 454 537. These devices mostly are connected toa duct or channel which is provided with a refractory coating and which extends between a glass furnace and a glass-processing machine. Sometimes the device is further provided with heating systems to keep the glass to be processed at Åa desired high temperature. The molten glass flows along the duct or channel to the discharge device and would then flow through the discharge reservoir and the discharge orifice(s) in a continuous stream to a further processing machine were it not for the presence of a vertically movable plunger in the discharge reservoir. This vertically movable plunger interrupts the glass stream and expels separate quantities of glass from the discharge orifice. When the plunger moves upwards, a restriction of the glass stream occurs, a shearing member being arranged at the relevant area to divide the glass stream into separate predetermined quantities of a size required for further processing. The size of the quantities can be further regulated by varying the movement of the plunger, for example, the stroke and the speed, or by varying the form and the cross-sectional area of the plunger. In this known device, problems arise when glasses of very low viscosity have to be processed. A glass of low viscosity will flow from the discharge orifice again soon after the operation of the shearing member. In order to avoid this as far. as possible and to compensate for the decreasing pumping effect, a 'plunger having a large crosssectional is required. Although it is thereby achieved that the glass is held back sufficiently at the discharge orifice by the upward movement of the plunger, however, the low viscosity of the glass gives rise to the additional phenomenon that the surface tension of the glass in the discharge orifice can no longer prevent air from ascending through the glass, whereupon glass flows out of the space between the wall of the discharge orifice and the plunger. It is then no longer possible to control the quantity of glass discharged. This problem also has already been described in DE-PS 1 207 052, in which it is proposed to solve this problem by providing an excess pressure below the discharge orifice in the periods in which there is no outflow of glass, if desired in combination with a pin temporarily closing the discharge orifice. This known device has the disadvantage that it has a complicated construction, requiring a pressure chamber and a closure pin between the discharge orifice and the further processing machine. The invention has for its object to provide a device of the kind mentioned above, in which the undesired outflow of glass is prevented by simple and compact means. According to the invention, the device is characterized in that in the discharge reservoir there is arranged coaxially with the centre of the or each discharge orifice a pin which is movable towards and away from the or the respective orifice and is disposed opposite the orifice and by which the orifice can be closed to a variable extent. According to one embodiment in which the reservoir is provided with only one discharge orifice and one discharge plunger the discharge plunger is arranged coaxially with the centre of the discharge orifice and is provided with a central axial bore in which the movable pin extends. In another embodiment, in which there is a plurality of discharge orifices in the discharge reservoir, one or more discharge plungers is or are arranged beside the pins arranged coaxially with the centres of the relevant orifices. In this way it is possible with constructionally simple means to vary the size of the discharge opening as desired during the discharge cycle so that an undesired discharge of glass is prevented and air bubbles cannot ascend in the glass. The invention will be described more fully with reference to the drawings. Figures la - le show diagrammatically a glassdischarge device with one discharge orifice at various stages in the discharge process; Figures 2a and 2b show diagrammatically a glassdischarge deyice with two discharge orifices; Figure 3 shows diagrammatically a mechanism for actuating the moving parts of the devices shown in Figures 1 and 2. In Figure 1, reference numeral 1 designates a discharge reservoir, which can be connected in a manner not shown to a glass furnace which supplies molten glass to the reservoir. The reservoirlis provided with a discharge orifice 2. In the reservoir 1 is arranged a vertically movable discharge plunger 3. This plunger 3 is provided with a central axial bore 4 in which extends a closure pin 5 which at its end adjacent the discharge orifice 2 is provided with an enlarged head 6. A rotatable cylinder 7 surrounds the disks charge plunger, which cylinder serves to agitate the glass melt. Instead of being provided with a rotatable cylinder, the device may alternatively be provided with a stationary cylinder, in which case separate agitating means are additionally provided. Below the discharge orifice 2 is arranged a shearing member 8 which serves to divide the outflowing glass into separate predetermined quantities. The operation of this device is as follows. In the situation shown in Fig. la, the discharge plunger 3 and the closure pin 5 move downwards together towards the discharge orifice, as a result of which a quantity of glass melt is discharged through the orifice 2. At the end of this stroke of the plunger 3 and pin 5 the direction of movement of the plunger 3 is reversed but the closure pin 5 remains in a position in which its head 6 partly closes the discharge orifice. When the plunger 3 moves upwards, the flow of glass is restricted and the discharged quantity of glass can be cut off by the shearing member 8. This is shown in Figure ib. Figure ic illustrates how the plunger 3, as it moves further upwards, exerts a sufficient suction effect on the glass to prevent glass from flowing out of the restricted discharge orifice. Figure id shows the situation in which the discharge plunger has completed its upward stroke. The direction of movement of the plunger is then reversed again, as is shown in Figure le, while at the same time the closure pin is pulled upwards so that the discharge orifice is freed and the process can be repeated. Thus, a comparatiely simple measure, namely, the addition of a closure pin which completely or partly closes the discharge orifice during the upward movement of the discharge plunger, results in a device whereby a glass melt of low viscosity can be discharged in controlled quantities of the desired size at the desired speed. An undesired discharge of glass melt or an undesired rising of air bubbles in the glass is thus prevented. Figure 2 shows diagrammatically how a device with two discharge orifices 2 and 2' is provided with two vertically movable closure pins 5 and 5t and two discharge plungers 3 and 3' arranged parallel to the pins. The plungers 3 and 3t have a form considerably different from that of the plunger- of Figure 1 but they have the same function and movement as the plunger of Figure 1. Again a cylinder 7 surrounds the plungers and closure pins, while Figure 2b shows in plan view how the device 1 can be connected via a flange 10 to the glass supply duct extending from the furnace. It should be noted that the plungers 3 and 3' may also form an integral part with one another. The discharge plungers 3 and 3' and the closing pins 5 and 5' can be actuated in the manner shown in Figure 3,for example. This figure shows the same discharge reservoir as Figure 2, with two discharge orifices 2 and 2', movable closure pins 5 and 5' and movable discharge plungers 3 and 31. The closure pins 5 and 5' are connected at their upper ends to a common yoke 11, while the discharge plungers 3 and 3t are supported by a common yoke 12. The yokes 11 and 12 are provided with sleeves 13 and 14, respectively, which are slidable on a rod 15 which is rigidly connected to a supporting frame at 16. The sleeves 13 and 14 are pivotally connected to levels 17.and 18, respectively, which are pivotable about fixed axes 19 and 20, respectively, the sleeves being pushed downwards by springs3' and 14'. The levers 17 and 18 are each coupled to a rod 21 and 22, respectively, whose length is adjustable by means of a screw threaded sleeve 23 and 24, respectively. The rods 21 and 22 are pivotally connected at one end to the levers 17 and 18, respectively through pins 25 and 26, respectively, the pins 25 and 26 being adjustable in slots 29 and 30, in the levers 17 and 18, respectively, by means of adjusting members 27 and 28, respectively. At their other ends, the rods 21 and 22 are pivotally connected at points 31 and 32, respectively, to levers 33 and 34, respectively, which are pivotable about fixed axes 35 and 36, respectively, and which through rollers 37 and 38, respectively, engage cam disks 39 and 40, respectively. The cam disks 39 and 40 are both coupled to a drive which is not shown. By rotation of the cam disks 39 and 40, the desired movements both of the closure pins 5 and 51 and of the discharge plungers 3 and 3' are obtained, the timing and duration of the movements being determined by the orifices of the cam disks. The timing of the strokes of the closure pins and the discharge plungers can be adjusted by adjusting the length of the rods 21 and 22, respectively, by means of the sleeves 23 and 24, respectively. The lengths of the strokes can be varied by varying with the aid of the adjusting members 27 and 28, respectively, the positions of the hinge pins 25 and 26, respectively, in the slots 29 and 30, respectively.

Claims: 1. A device for discharging controlled quantities of molten glass from a discharge reservoir provided with at least one discharge orifice, at least one vertically movable discharge plunger being arranged in the discharge reservoir, characterized in that in the discharge reservoir there is arranged coaxially with the centre of the or each discharge orifice a pin which is movable towards and away from the or the respective orifice and is disposed opposite the orifice and by which the orifice can be closed to a variable extent. 2. A device as claimed in Claim 1, in which the discharge reservoir is provided with only one discharge orifice and one discharge plunger, characterized in that the discharge plunger is arranged coaxially with the centre of the discharge orifice, the plunger being provided with a central axial bore in which the movable pin extends. 3. A device as claimed in Claim 1, in which the discharge reservoir is provided with a plurality of discharge orifices, characterized in that one or more discharge plungers is or are arranged beside the pins arranged coaxially with the centres of the relevant orifices.

Inventors: ROMBERG, HENDRIK
Applicants: N.V. PHILIPS' GLOEILAMPENFABRIEKEN
Application year: 1983
Main classification: C03B7
IPC codes: C03B7