WO1992011215A1

WO1992011215A1 - Gob-forming apparatus, including refractory cylinder

Info

Publication number: WO1992011215A1
Application number: PCT/GB1991/002292
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: 1991-12-20
Publication date: 1992-07-09
Anticipated expiration: 1993-06-21
Also published as: AU9121491A; GB9027850D0; CS394391A3; ZA9110035B

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. The size of the gobs is regulated by the quantity of molten glass available to be forced through the orifices (6, 7) by the plungers (20, 21), which is regulated by the height the lower end of a metering tube (30) circumscribing the plungers (20, 21) is from the trough floor (1). The height of the lower end of the tube (30) may be varied by means of a screw-threaded axially-movable collar (42) engaged by a ring (44) able to be rotated about the collar (42) at a fixed height above the trough (1).

Description

GOB-FORMING APPARATUS. INCLUDING REFRACTORY CYLINDER

This invention relates to gob-forming apparatus comprising a refractory cylinder. 5

In the manufacture of glassware, particularly of glass bottles, the glassware is formed from gobs of molten glass. These glass gobs are obtained by forcing molten glass through an orifice in the floor of a refractory

10 trough containing the molten glass from a glass furnace. The glass is forced through the furnace by means of an vertically-reciprocating plunger aligned with the orifice. Below the orifice, the gob is cut off by gob- shearing apparatus, and drops away. The glass gob,

15 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

• 20 production is often further increased by using multi-gob installations.

Within the trough and around the plunger(s), there is generally provided a refractory metering cylinder. In use, this cylinder is often rotated about its longitudinal axis to stir the molten glass in the trough. Alternatively the molten glass may be stirred by the use of a rotating paddle in order to ensure the homogeneity of the glass.

The height of the cylinder above the floor of the trough is generally adjustable, so that by varying the cylinder's 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 the metering cylinder is used to adjust the weight of the gobs used.

Generally speaking, the metering cylinder is suspended in the trough from an arm mounted on a pillar to one side of the trough. Thus the cylinder is cantilevered out from the pillar, and it is generally raised or lowered, to adjust the height of the cylinder above the trough floor, by raising or lowering the pillar. This arrangement puts a great deal of strain on the apparatus, and it is difficult to adjust the height of the cylinder accurately above the trough floor using such apparatus. Indeed, with the cantilever arrangement, it can be the case that the cylinder is not raised and lowered entirely vertically and thus the cylinder may become skewed with respect to the vertical axis of the apparatus, leading to inaccuracies of molten glass flow rate and resulting gob size.

According to the present invention there is provided gob- forming apparatus including a cylindrical tube adapted to circumscribe one or more plungers cooperating with one or more orifices in-the floor of a refractory trough, and means for adjusting the height of the tube from the trough to control flow of molten glass from outside the tube to the orifice(s) , wherein the tube height adjustment means includes an externally screw-threaded collar surrounding the tube and fixed axially relative thereto, and a rotary ring engaged with the screw- threads of the collar, and at a fixed height above the floor of the trough, and means for rotating the ring with respect to the collar.

If desired to rotate the tube about its axis in known fashion to stir the molten glass, this may be achieved by installing a suitable annular bearing between the threaded collar and the tube, and providing an external sprocket or toothed ring attached to the tube.

Suitably the rotary ring is mounted on a bridge spanning the trough. Most preferably the gob-forming apparatus according to the present invention is as described in our co-pending GB patent application 90 27849.0.

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 rotatably-driven 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; Figure 4 is a plan view of the apparatus of Figure 3;

Figure 5 is a side elevation of a collar supporting the rotary metering cylinder in a preferred embodiment of the invention;

Figure 6 is a view, part in section and part in elevation, of rollers carried by a rotary ring for lifting and lowering the collar of Figure 5;

Figure 7 is an axial cross-section on a larger scale, showing the construction of the rollers shown in Figures 5 and 6, and

Figure 8 is a plan view of the rotary ring of Figure 6.

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 trough 1 is made of highly thermally-insulating material, and insulating 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 trough 1. Mounted on pillars 11 is a plate 12 having in it an aperture 13 above the trough 1. Mounted on pillars 11 and plate 12 is a further pair of pillars 14, extending between which is a bridging member 16. Various parts of support 10 are separable one from another, and are pivotally 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 and aligned with the orifices 6, 7. The plungers 20 and 21 extend through the aperture 13 in plate 12, and depend from respective plunger chucks 22, 23 supported by a support jig 24. The jig 24 is connected to a drive motor 25 mounted on bridge member 16. The drive motor 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 metering cylinder 30 of refractory material is suspended from a chuck 31 and extends down through aperture 13 in plate 12 to circumscribe the plungers 20 and 21. In Figure 1 the cylinder 30 is shown in its lowermost position.

Chuck 31 is mounted in a gear wheel 32 engaging the drive wheel 33 of a motor 34 mounted on the support 10. The drive wheel 33 extends vertically such that the gear wheel 32 can engage drive wheel 33 over a vertical range of movement of gear wheel 32.

Chuck 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 correspondingly internally screw-threaded nut 44. Nut 44 is provided with external gear teeth rotated by means of a meshing gear wheel 45 driven by a motor 46 mounted on plate 12. The gear wheel 45 can also be engaged by a manually- drivable 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 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, in conventional manner, 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 rotation of cylinder 30, and the cylinder 30 also acts as a metering valve controlling, by its height above the floor of trough 1, 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 causing rotation of drive wheel 33. Drive wheel 33 in its turn rotates gear wheel 32 on which the cylinder 30 is suspended via chuck 31.

The height of the cylinder 30 above the floor of trough 1 is adjusted by means of the vertical height of cylinder 42 on which the cylinder is supported, via chuck 31, support ring 40 and bearing ring 41. Rotation of drive wheel 45, either by means of motor 46 or manually by cog wheel 47, causes the screw-threaded nut 44 to rotate. As a result of this rotation, 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 has an elongated vertical axis, 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 means for raising, lowering and rotating the cylinder are all provided on the support 10. 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 of the accompanying drawings is largely identical with that shown in Figures 1 and 2. Those components of the second embodiment of the invention which are the same as the first embodiment are given the same reference number, plus 100.

The major difference between the two embodiments is that in the second one the metering cylinder 130 is non- rotary, and in that a rotatable paddle 150 projects into trough 101. The 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 a drive wheel 155 of a motor 156 also mounted on the plate 112.

In use of the apparatus of Figures 3 and 4, the mode of operation is largely the same and so will not be described herein any detail, being deducible easily from the description of the Figures 1 and 2 embodiment.

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 metering 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 partially dismantled and various parts pivoted away from the trough for maintenance.

In that preferred form of the invention shown in Figures 5 to 8, the collar 42 of Figure 1 is replaced by a collar 200 having a three-start helical thread 202 on its outer surface. The collar depends from a ring 204 having in it a slot in which works a fixed vertical pin 206 to ensure that the collar does not rotate as its height from the trough 1 of Figure 1 is adjusted. By means of two sets of ball races 208 a ring 210 is supported for relative rotation. The ring 210 is analogous to ring 32 of Figure 1 in that it takes the weight of metering cylinder 30 and is able to be rotated continuously to keep the molten glass stirred by means of cylinder 30.

Engaging the threads 202 are three pairs of rollers 212 carried by a ring 214 having its weight borne in turn by an annular support 216, through a ball race 218, the support 216 being attached to the platform 12 spanning the trough. The rollers of each pair 212 engage the substantially triangular sectioned thread 202 in a manner in which the weight of the collar 200 is transferred to ring 214.

As shown in Figure 8, the pairs of rollers 212 are mounted on ring 214 at angles of 120° from each other. As there are three helical threads 202, they are contacted by rollers 212 in a plane perpendicular to the axis of collar 200.

It will be seen that, as the ring 214 is rotated in the appropriate direction by means of an equivalent to motor 46, gear-wheel 45 or sprocket 47 of Figure 1, rotation of the rollers 212 about the axis of collar 200 (in a low- friction manner) is effective to raise or lower the collar and with it the metering cylinder 30.

Although the invention has been described in connection with an externally-threaded collar engaged by an external height-control ring, it is within the purview of this invention to use an internally-grooved or threaded collar engaged internally by a rotary spider or other height- control member able to take the weight of the collar and the members carried by it.

Claims

1. A gob-forming apparatus including an upright cylindrical metering tube of refractory material adapted to circumscribe at least one vertically- reciprocable plunger cooperating with an orifice in the floor of a trough of refractory material to extrude gobs of fused material therefrom, the tube having the height of its lower end from the trough floor adjustable by means of an axially-movable collar supporting the tube and being engaged by a height-control member able to be rotated relatively to the collar at a fixed height from the trough to adjust the height of the collar from the trough.

2. Apparatus as claimed in claim 1, including means for rotating the tube irrespective of its height from the trough.

Apparatus as claimed in claim 1 or 2, in which the height-control member takes the form of a ring movable around the exterior of the collar along a helical path relative to the collar.

4. Apparatus as claimed in claim 2 or claims 2 and 3, in which there is an annular bearing between the collar and the tube, and in which the tube has a gear-wheel movable with it and engaged by a otor- driven pinion wheel of axial length commensurate with the range of adjustment of the tube height.

5. Apparatus as claimed in claim 3 or 4, in which the height-control ring is able to be rotated by either a motor-driven gear-wheel or a manually-rotatable cogwheel.

6. Apparatus as claimed in claim 5, in which the cogwheel is permanently enmeshed with a motor-driven gear-wheel.

7. Apparatus as claimed in any preceding claim, including a paddle adapted to extend into the trough and to follow a circular path around the exterior of the metering tube, the paddle being movable with a motor-driven gear-wheel at a fixed height above the trough.

8. Apparatus as claimed in any preceding claim, in which the collar has an external screw-thread engaged by an internal screw-thread on the ring.

9. Apparatus as claimed in any of Claims 3 to 6, in which the collar has a multi-start external screw- thread, and in which the ring carries a plurality of low-friction rollers, each engaging one of the said external screw-threads, with the contacts between the rollers and the threads being co-planar.

10. Apparatus as claimed in Claim 9, in which the collar carries three uniformly-pitched screw-threads, and in which there are three rollers engaging the threads at locations spaced apart angularly by 120°.