STRAIGHT LINE GOB SHEARING APPARATUS

Abstract: A straight line gob-shearing apparatus for a molten glass gob forming installation comprising two reciprocally driven shear blade carriages (7, 8) bearing shear blades (9, 10, 11, 12) mounted on wayrods (1, 2). Each carriage (7, 8) is directly mounted on to a wayrod (1 or 2) and indirectly mounted on to the other wayrod (1 or 2) by way of the other carriage (7 or 8). Such arrangement has the effect of being self-compensating for differential wear and the differential expansion commonly experienced at the high temperatures of modern glass gob forming apparatus.

Description: STRAIGHT LINE GOB SHEARING APPARATUS This invention relates to straight line gob shearing apparatus. 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 trough containing the molten glass from a glass furnace. The glass is forced through the orifice by means of an axially reciprocating plunger above 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 speed operation for the apparatus. Moreover, gob production is often further increased by using multi-gob installations. The gobs are cut off by means of shears mounted below the orifice in the refractory trough. In straight line shearing apparatus, at least two opposing shear blades are reciprocally moved along a straight line towards and away from each other between the closed, cutting position, in which the gob is cut off below the orifice, and the open position to allow formation of the next gob. In multi-gob installations, a plurality of opposing shear blades is mounted in parallel such that a plurality of gobs may be sheared simultaneously. Such straight line shearing apparatus is for example is described in European Patent Application 0 164 902. Conveniently, in straight line shearing apparatus, the opposing shear blades are mounted on carriages which extend between parallel wayrods, each carriage carrying at least one shear blade. The carriages are slidably mounted on the wayrods and reciprocally driven between the closed, cutting position and the open position. Generally one shear blade carriage is slidably mounted and driven reciprocally on one or more wayrods on one side of the apparatus and rests on a second wayrod, and the second shear blade carriage is slidably reciprocally driven on the second wayrod and rests on the first wayrod. While this construction is convenient for ease of operation and minimising friction on the wayrods, it does lead to differential wear, particularly at the high speeds and high temperatures of modern glass gob producing apparatus. Also the high temperatures have a tendency to result in differential expansion of the shear blade carriages. Both of these effects can lead to distortion, resulting in the shear blades becoming skewed with respect to each other, and thus in inefficient shearing of the gobs. According to the present invention there is provided a straight line gob-shearing apparatus comprising a pair of carriages reciprocally movable toward and away from one another on parallel wayrods for carrying at least one pair of co-acting shear blades, wherein each carriage is supported slidably at one side on one or more wayrods and in parallel sliding fashion on its other side on an axial projection fixed to the other carriage. Preferably the axial projection is a sleeve surrounding the wayrod on which the one side of the other carriage is slidably mounted. Thus, according to the present invention, each shear blade carriage, while being slidably mounted on one side on wayrod(s) on the other side is slidably mounted on a projection of the other shear blade carriage. This has the effect that differential wear and differential expansion of the shear blades is compensated for. The invention is further described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view, with part cut away, of a straight line gob-shearing apparatus according to the present invention, and Figure 2 is a section on the line A-A of Figure 1; Figure 3 is a plan view of a modified shear blade carriage of the present invention; Figure 4 is a section on line IV-IV of Figure 3, showing a dual pad support arm, and Figure 5 is a section on line V-V of Figure 3, showing a support arm terminal guide. There is shown in the drawings apparatus according to the present invention having two pairs of opposing shear blades for use in a double-gob installation. However, the apparatus may be used in single-gob installations requiring only one pair of opposing shear blades or, using more pairs of shear blades, in triple etc. gob installations. Referring to the drawings, the apparatus comprises parallel wayrods 1 and 2 extending between one end plate 3 and a housing (not shown) . Opposing shear blade carriages 7 and 8 extend between parallel wayrods 1 and 2 and have mounted webs 25 thereof opposing shear blade pairs 9 and 10, and 11 and 12. The position, in use of the apparatus, of gobs between the shear blades is indicated in Figure 1 in feint line. Shear blade carriage 8 is slidably mounted on wayrod 1 by means of sleeve 15. The sleeve 15 is provided, at each end, with bushes 16 which slide on the wayrod 1. Pivotally connected to sleeve 15, by means of pivot pin 18, is a connecting rod 19 connected to reciprocal drive means (not shown) whereby sleeve 15 and shear blade carriage 8 are reciprocally driven on wayrod 1. In analogous manner to the mounting of shear carriage 8 on wayrod 1, shear blade carriage 7 is provided with a sleeve 21 which is slidably mounted on wayrod 2. Also, in analogous fashion to sleeve 15, sleeve 21 is provided with a pivot pin and connecting rod to reciprocal drive means (not shown) whereby sleeve 21 and shear blade carriage 7 may be reciprocally driven on wayrod 2. The drives provided are such that the shear blade carriages 7 and 8 are moved towards each other on wayrods 1 and 2 to advance the opposing shear blade pairs 9 and 10 and 11 and 12 to the closed cutting position, and away from each other to the open position. On the upper part of sleeve 21 is mounted a longitudinal slide-way 22 (e.g. a hard metal wear plate) on which rests a support arm 23 projecting from the web 25 of shear blade carriage 8. The underside of arm 23 is provided with a wear pad 26, for example a metal wear pad (shown in Figure 2). In a similar manner, a support arm 25 having a wear pad 26 and projecting from shear blade carriage 7 rests on a longitudinal slide-way 22 mounted on the upper side of sleeve 15. In use, the apparatus according to the present invention, with shear blades in place, is positioned under the two extrusion orifices of a refractory trough through which fused glass is forced by means of plungers reciprocating thereabove. With the extrusion of a gob to between the opposing shear blades, the shear blades are moved from their open position (as shown in Figures 1 and 2) , by means of the drive means acting on the connecting rods 19 connected to sleeves 15 and 21, which slide on their respective wayrods 1 and 2 to their closed, cutting position. The shear blades are thereafter retracted to the open position ready for formation of the next gobs. As the apparatus moves to the closed position, sleeve 15 and shear blade carriage 8 slide on wayrod 1 towards the left (as viewed in Figures 1 and 2), and the shear blade carriage 7 and sleeve 21 on their respective wayrod 2 move to the right as viewed in Figure 1. Additionally, arm 25 extending from shear blade carriage 7 will slide to the right on plate 22 and, in a similar way, the arm 23 projecting from shear blade carriage 8 will move to the left on plate 22 on sleeve 21 as the apparatus moves to the closed, cutting position. As the apparatus moves to its open, standby, position, the arm 25 will move back to the left on plate 22 of sleeve 15, and the arm 23 will move to the right on plate 22 of sleeve 21. In this way each shear blade carriage is supported, on one side, on the sleeve slidably mounted on its respective wayrod, and on the other side on the sleeve on which the other shear blade carriage is supported. In this way, wear effects are evened out. Moreover the construction is substantially insensitive to heat expansion as each shear blade carriage is supported by, and moves on, a plate provided on the other shear blade carriage. As shown in Figure 3, in a modified form of shear blade carriage, each longer arm of the carriage has a support block 28 secured to one end of slide-way 22 by means of screws 30. The screws hold a guide plate 32 on block 28 in cantilever fashion. As can be seen from Figure 4, the shorter support arm 25 of each carriage carries a low- friction pad 34 on its upper (as viewed) surface, to complement pad 26 on its lower surface. The height of block 28 is substantially equal to the distance between the contact surfaces of pads 26 and 34. Being positioned at the cutting end of the stroke of the two carriages, as the carriages near each other, each support arm enters the space 36 between guide plate 32 and its associated slide-way, in which the two pads are a sliding, load- bearing, fit. The entry of each arm 25 into the space 36 is facilitated by a bevel 38 on the respective edge of plate 32, to accommodate any misalignment or vibration there might be between the shear blade carriages as the shear blades 9-12 (Figure 1) encounter and shear through the protruding gobs. This gives significant extra strength and stability to the carriages 7 and 8, making them even less sensitive to the deleterious effects of differential thermal expansion etc.

Claims: CLAIMS 1. Straight-line gob-shearing apparatus comprising a pair of reciprocally-moveable shear blade carriages (7, 8) mounted for slidable movement on two parallel wayrods (1, 2) and connected to means (19) for driving them in opposite directions between a closed cutting position and open rest position, characterised in that each of the carriages has part of its weight borne directly by one of the wayrods, and has the rest of its weight borne by a support arm (23, 25) thereof in sliding contact with the other carriage, or with a member (22) movable therewith. 2. Apparatus as claimed in claim 1, characterised in that each carriage comprises a sleeve (15) working on one of the wayrods, and in that it is the sleeve, or a member (22) secured thereto, on which the support arm of the other carriage bears. 3. Apparatus as claimed in claim 1 or 2, characterised in that each sleeve (15) is connected to, or integral with, a web adapted to function as a holder for at least one blade (9 to 12) of at least one pair (9/10, 11/12) of co-operating gob-cutter blades, and in that the respective support arm (23, 25) projects forwardly of the web towards the opposite carriage. 4. Apparatus as claimed in any preceding claim, characterised in that each support arm carries a pad (26) of wear-resistant material in sliding contact with a slide-way (22) of wear-resistant material carried by the other carriage. 5. Apparatus as claimed in claim 4, characterised in that each slide-way (22) has a parallel guide plate (32) secured to it in cantilever fashion to define a housing (36) for the support arm of the other carriage when the two carriages are in their cutting position. 6. Apparatus as claimed in claim 5, characterised in that each support arm carries a second pad (34) adapted to come into sliding contact with an inner face of the guide plate. 7. Apparatus as claimed in claim 6, characterised in that at least the respected edge of an end face of the second pad (34) or of the guide plate (32) is bevelled or chamfered (38) to act as a cam surface for the opposing member as both carriages move towards their closed position.

Inventors: ANDERSON LARS TORE, ANDERSON, LARS, TORE
Applicants: BHF ENG LTD, BH-F(ENGINEERING) LIMITED
Application year: 1991
Main classification: C03B7
IPC codes: C03B7