WO1992011214A1

WO1992011214A1 - Gob-forming apparatus

Info

Publication number: WO1992011214A1
Application number: PCT/GB1991/002267
Authority: WO
Inventors: Lars Tore Anderson
Original assignee: BH-F (ENGINEERING) Ltd
Current assignee: BH-F (ENGINEERING) Ltd
Priority date: 1990-12-21
Filing date: 1991-12-18
Publication date: 1992-07-09
Anticipated expiration: 1993-06-21
Also published as: GB9027849D0; CS394491A3; AU9101791A; TW203033B; ZA9110032B

Abstract

In the manufacture of glassware gobs of molten glass are formed by gob forming apparatus. A gob is formed by the action of vertically reciprocating plungers (20, 21) forcing the glass down through orifices (6, 7) in the floor of a trough (1) below which orifices shear blades separate the gob. A bridge (10) is mounted spanning the trough on which means (25) reciprocating the plungers (20, 21) is mounted. Also mounted on the bridge (10) is a hollow metering cylinder (30) via its suspension means. The suspension means is mounted on the bridge (16) nearer to the trough (1) than the reciprocating means (25). Means for altering the vertical position of the metering cylinder (30) and for rotating it about its major axis are also mounted on the bridge (10).

Description

GOB-FORMING APPARATUS

This invention relates to gob-forming apparatus.

In the manufacture of glassware, particularly of molten glass bottles, the glassware is formed from gobs of molten glass. These glass gobs are obtained by forcing molten glass though an orifice in the floor of a refractory trough containing molten glass from a glass furnace. The glass is forced through the orifice by means of a vertically-reciprocating plunger aligned with the orifice. Below the orifice the gob is cut off and drops away. The glass gob, whilst still hot, then undergoes further treatment, e.g. moulding into the desired glassware.

Increased production rates have brought with them high speeds of operation for the apparatus. Moreover gob production is often further increased by the use of multi-gob installations.

Within the trough and around the plunger(s) there is generally provided a refractory metering cylinder. The height of the bottom end of this cylinder above the trough floor is generally adjustable, so that by varying its height above the trough floor, and thus also its height above the orifice(s) , the rate of flow of glass to the orifice(s) is varied. In this way it is possible to adjust the weight of the gob produced.

Additionally, the refractory cylinder is often rotated about the reciprocatory plunger(s) , or a revolving paddle is provided to stir the glass in the trough and maintain homogeneity.

In conventional gob-forming apparatus, each plunger is generally mounted on the end of an arm extending from a pillar which is reciprocally driven up and down. Thus as the pillar is reciprocated, each plunger at the end of the arm mounted on the pillar is also reciprocated in line with its respective orifice. However, this conventional arrangement applies considerable strain and weight on the pillar and the apparatus for reciprocating the pillar. Further, with wear, it can be that the movement of the plungers becomes skewed and no longer vertical.

In addition, it is often the case that the refractory cylinder is mounted on the end of an arm cantilevered from the side of the trough.

According to the present invention there is provided gob- forming apparatus comprising a refractory trough; at least one orifice in the floor of the trough; at least one vertically-reciprocable plunger located with its axis intersecting the orifice; means for reciprocating each plunger to force molten glass through the aligned orifice to form gobs, arid a bridge spanning the trough and at the centre of which the reciprocation means is mounted.

Preferably the plungers are circumscribed by a refractory metering cylinder which is also mounted on the bridge at a lower level than the reciprocation means. The bridge may support apparatus for raising and lowering the refractory cylinder relative to the trough, and/or for rotating the cylinder about its axis. The bridge may also support a rotary stirrer means, e.g. a paddle projecting into the molten glass from a horizontal drive ring, and a motor to rotate that drive ring. Because the weight of at least the plunger reciprocation means is applied at the centre of the bridge, there are no forces tending to skew the plungers, so tht the vertical path along which they move remains fixed despite wear, leading to uniformity of gob size during long production runs.

Preferably the gob-forming apparatus according to the present invention comprises means for raising and lowering the refractory cylinder as described in our co-pending British patent application number 9027850.8.

This invention is further illustrated, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a section through a gob-forming apparatus according to the present invention, comprising a rotary refractory metering cylinder;

Figure 2 is a plan view of the apparatus of Figure 1;

Figure 3 is a section through a gob-forming apparatus according to the present invention having a non-rotary cylinder, and Figure 4 is a plan view of the apparatus of Figure 3.

Referring to Figures 1 and 2 of the accompanying drawings, the gob-forming apparatus comprises a refractory trough 1 forming a spout of a forehearth (not shown) of a glass furnace for the delivery of molten glass to the trough 1. The refractory trough 1 is made of thermal insulation material, and insulation blocks 2, 3, 4 extend across the trough mouth to reduce heat loss. In the floor of the trough 1 is a pair of orifices 6 and 7.

Bridging the trough 1 is a support 10 comprising a pair of pillars 11, one mounted on each side of the trough. On pillars 11 is mounted a plate 12 having in it an aperture 13 above the refractory trough 1. Mounted on plate 12 is a further pair of pillars 14, extending between which is a bridging member 16. Various parts of support 10 are separable from each other and relatively movable to permit access to various parts of the apparatus.

The gob-forming apparatus of Figures 1 and 2 further comprises a pair of gob-forming plungers 20, 21 mounted above the orifices 6, 7. The plungers 20 and 21 extend through the aperture 13 in plate 12, and depend from plunger chucks, 22, 23 supported on a jig 24. The jig 24 is connected to drive means 25 mounted on bridge member 16. The drive means 25 drives the support jig 24, and with it plungers 20, 21, with a vertically-reciprocating motion so that the plungers move up and down with respect to their corresponding orifices 6, 7.

A refractory cylinder 30 is suspended from a cradle 31 and extends down through aperture 13 in plate 12 and circumscribes the plungers 20 and 21. In Figure 1 the refractory cylinder 30 is shown in its lowermost position.

Cradle 31 is mounted in a gear wheel 32. The gear wheel 32 engages the drive wheel 33 of a motor 34 mounted on the support 10. The drive wheel 33 has a height such that the gear wheel 32 can engage drive wheel 33 over the range of movement of gear wheel 32.

Cradle 31 is also supported by a ring 40 mounted, via bearing ring 41, on a large cylinder 42 having an external screw-thread 43. Mounted around cylinder 42, and in engagement therewith, is a corresponding internally screw-threaded nut 44 rotatably driven by means of the drive wheel 45 of a motor 46 mounted on plate 12. The drive wheel 45 can also be engaged by a manually-driven cog wheel 47, also mounted on plate 12.

For use, the gob-forming apparatus of Figures 1 and 2 is set up as shown. Molten glass from the glass furnace is supplied to refractory trough 1. The plungers 20, 21 are vertically reciprocated in line with orifices 6, 7. On the downward stroke of the plungers, molten glass is forced out through the corresponding orifice 6, 7 to form a gob. The gob formed is cut off, using gob-shearing apparatus, and removed during the upward stroke of the plunger, for further processing.

The molten glass in trough 1 is stirred by means of rotation of cylinder 30. The cylinder 30 also acts as a metering valve controlling, by its height above the floor of the trough, the rate of flow of the molten glass to the orifices 6, 7, and thus the gob weight.

The cylinder 30 is rotated by means of motor 34, which rotates drive wheel 33. Drive wheel 33 in its turn rotates gear wheel 32 from which the cylinder 30 is suspended via cradle 31. Thus, as the gear wheel 32 is driven round by drive wheel 33 of motor 34, the cylinder 30 is caused to rotate.

The height of the cylinder 30 above the floor of the trough is adjusted by means of the vertical height of cylinder 42 from which the cylinder 30 is supported, via cradle 31, support ring 40 and bearing ring 41. Rotation of drive wheel 45, either by means of motor 46 or manually by driving of cog wheel 47, causes the nut 44 to rotate. This rotation, and the engagement of the internal thread of nut 44 and the external thread 43 on cylinder 42, causes the cylinder 42 to be raised or lowered, depending upon the direction of rotation. In this way the height of the cylinder 30 above the floor of trough 1 can be adjusted. Of course, with the raising and lowering of the cylinder 30, the height of gear wheel 32 with respect to drive wheel 33 will be varied but, because the drive wheel 33 extends vertically, the gear wheel 32 will still engage the drive wheel 33 for rotation of the cylinder 30.

Thus, with the apparatus of Figures 1 and 2, the plunger drive mechanism, and the raising and lowering device and rotational drive for the metering cylinder, are all provided on the support 10, which spans the trough 1. For access to the gob-forming apparatus for maintenance, the support 10 can be dismantled and/or parts of it pivoted out of the way to permit access. Referring now to the gob-forming apparatus shown in Figures 3 and 4 of the accompanying drawings, it is to be noted that, in Figure 3, the support is shown only partly.

The gob-forming apparatus shown in Figures 3 and 4 comprises a trough 101 forming a spout of a forehearth (not shown) of a glass furnace for the delivery of molten glass to the trough 101. In a similar way to the trough 1 of Figures 1 and 2, the trough 101 is made of highly thermally-insulating material, and insulation blocks 102, 103 extend across the trough mouth to reduce heat loss. In the floor of trough 101 is a pair of orifices 106 and 107.

Bridging the trough 101 is a support 110 comprising a pair of pillars 111, one mounted on each side of trough 101. On pillars 111 is mounted a plate 112 having in it an aperture 113 above trough 101. Mounted on plate 112, on a further pair of opposing pillars 114 (only one shown) , is a second plate 115 having in it an aperture 116 above trough 101 and aperture 113. The support 110 further comprises a bridge member 117 which spans the support and is mounted on pillars 114 and plate 115. As with support 10 of Figures 1 and 2, support 110 is separable and movable for access to the apparatus for maintenance.

The gob-forming apparatus of Figures 3 and 4 further comprises a pair of gob-forming plungers 120, 121 mounted above orifices 106, 107. Plungers 120 and 121 extend through the aperture 113 in plate 112, and are mounted on plunger chucks 122, 123 respectively, which plunger chucks extend through the aperture 116 in plate 115. The plunger chucks 121 and 123 are supported on a jig 124 connected to drive means 125 mounted on bridge member 117. The drive means 125 cause vertical reciprocation of the plungers 120, 121.

A hollow metering cylinder 130 is suspended from a cradle 131 and extends down through apertures 116 in plate 115, and 113 in plate 112, circumscribing the plungers 120 and 121. In Figure 3, the cylinder 130 is shown in substantially its lowermost position.

Cradle 131 is supported on a large-diameter cylinder 142 having an external screw-thread 143. Mounted around cylinder 142 is a correspondingly internally screw- threaded nut 144, which is rotatable by means of drive wheel 145 of a motor 146 mounted on second plate 115.

The gob-forming apparatus of Figures 3 and 4 further comprises a rotary paddle 150 within the trough. The rotary paddle 150 is supported on an arm 151 movable with a gear wheel 152 mounted on plate 112 via a bearing 153 and support member 154. Gear wheel 152 is rotatably driven by means of the drive wheel 155 of a motor 156 also mounted on the plate 112.

In use of the apparatus of Figures 3 and 4, molten glass from the glass furnace is provided to trough 101. Gob- forming plungers 120, 121 are reciprocally driven up and down by means of drive means 125. The drive means 125 drives the support jig 124 up and down and thus, with it, the plungers 120, 121 mounted on the jig via chucks 122, 123 are axially reciprocated above their respective orifices 106, 107. On the downward stroke of plungers 120, 121, molten glass is forced down through orifices 106, 107 to form two gobs. The gobs are cut off using gob-shearing apparatus, and removed during the upward stroke of the plunger for further processing.

The rate of flow of glass to the orifices 106, 107, and thus the gob size, is adjusted by adjustment of the height of the refractory cylinder 130 above the floor of the trough 101. This height adjustment is achieved by adjustment of the height of cylinder 142 on which the refractory cylinder 130 is supported via cradle 131. The external thread 143 of cylinder 142 is engaged by the internal thread of nut 144, which is rotated by rotation of the drive wheel 145 of motor 146. Depending upon the direction of rotation of nut 144, the cylinder 142, and with it refractory cylinder 130 suspended thereon, will be raised or lowered to adjust the rate of flow of molten glass to the orifices.

In addition, during use of the apparatus of Figures 3 and 4, the molten glass in trough 101 is stirred by means of paddle 150. The paddle 150 describes a circular path within the trough outside the cylinder 130. The paddle 150 is driven by means of motor 156, the drive wheel 155 of which engages the gear wheel 152 on which the arm 151 on which paddle 150 is supported. Thus, on rotation of the gear wheel, the rotatable arm 151 and paddle 150 are rotated about the cylinder 130.

Thus, in the apparatus of Figures 3 and 4, as in that of Figures 1 and 2, the various parts of the apparatus are supported across the trough. The support 101 can be dismantled and various parts moved away from the trough for maintenance.

Claims

Gob-forming apparatus comprising: a trough of refractory material having in its floor at least one orifice through which a gob of molten material can be extruded; at least one reciprocatory plunger aligned with the orifice, and a bridge spanning the trough and at the centre of which is mounted means for reciprocating each plunger.

2. Apparatus as claimed in claim 1, in which the plunger(s) is or are circumscribed by a hollow metering cylinder of refractory material which is suspended from the bridge at a level nearer to the trough than the reciprocation means.

3. Apparatus as claimed in claim 2, in which the cylinder suspension means is adapted to alter the height of the lower end of the cylinder from the trough.

4. Apparatus as claimed in claim 2 or 3, in which the bridge also supports means for rotating the cylinder about its axis.

5. Apparatus as claimed in any preceding claim, in which the bridge also supporting a rotary stirrer extending into the interior of the trough, the stirrer being movable with a horizontal gear wheel able to be driven by a motor of which the weight is also borne by the bridge.

6. Apparatus as claimed in claim 5, in which the rotational axis of the stirrer gear wheel is coaxial with the axis of the metering cylinder.