MXPA98002707A - Method and apparatus for controlling the flow of glass lined in a glass current contrachap - Google Patents

Abstract

The present invention relates to: An apparatus (10) for forming a plywood current having an inner core glass surrounded by an outer facing glass, including a first hole (24) for receiving the core glass a first source (12). A second hole (26) vertically forms a space below and aligns with the first hole, and is surrounded by a chamber (30) communicating with the second hole through a gap between the first and second holes. A discharge tube (36) supplies the coating glass from a second source (40) through a tube (32) to the chamber, so that the glass flows by gravity from the first and second sources through the glass. the holes to form the plywood current. The speed of the glass flow through the second source or coating glass (40) is measured and compared with one or more pre-set limits (78). The flow rate of the coating glass from the second source to the chamber surrounding the holes is adjusted when the flow velocity through the second source moves away from the preset limit. In this way, the desired ratio of coating glass to core glass, and consequently the thickness of the coating glass layer, is automatically maintained.

Description

METHOD AND APPARATUS FOR CONTROLLING THE FLOJO OF GLASS LINED IN A PLYWOOD GLASS CURRENT Field of the Invention The present invention is directed to the supply of a glass stream to form fillers or masses of molten glass for the manufacture of glassware, and more particularly, to a method and apparatus for supplying a so-called plywood glass stream in which a core or inner glass is surrounded by a coating or external glass layer.

Background of the Invention It has hitherto been proposed to supply a stream of plywood to form glass articles having wall segments in layers. The requests European Patent Nos. EPO 722907A2 and EPO 722908A2 describe techniques for supplying such a stream of plywood in which the core glass of a first source is supplied through a first hole. A second hole is below vertically spaced and aligned with the first hole, and is surrounded by an annular chamber communicating with the second hole through the gap between the first and second holes. A heated tube delivers the glass of REF: 27166 coating from a second glass source to the annular chamber surrounding the second hole. The glass flows by gravity from the first and second sources through the first and second orifices so that a stream of plywood emerges from the second orifice. This plywood glass stream can be cut by conventional techniques to form individual plywood melt masses to supply conventional single section glass article forming machines.

Although the techniques described in the annotated patent applications address and overcome the problems hitherto existing in the art, further improvements are desirable. For example, an important factor in the proper manufacture of plywood articles is to maintain a desired relationship between the coating glass and the core glass. Due to the higher operating temperatures in the coating glass system, refractory erosion is high in the coating glass discharge tube, which in turn requires that the glass flow through the glass discharge tube Coating is often adjusted to compensate for the erosion enlargement of the flow path. The flow rate of the coating glass is also affected by changes in ambient temperature that affect the designs in the refining furnace and the discharge tube, changes in the opening of the discharge tube cover around the control tube. flow of the discharge tube, changes in the gas heating manually adjusted in the discharge tube, and vibrations or disturbances in the positioning mechanism for the flow control tube. Adjustments to the flow of the coating glass discharge tube are currently made by manually adjusting the position of a flow control tube within the coating glass discharge tube. It is a general objective of the present invention to provide a method and apparatus for automatically controlling the flow rate of glass through the coating glass discharge tube, so as to maintain the desired ratio between the coating and core glasses in the plywood glass stream. Another more specific objective of the present invention is to provide a method and apparatus of the described character for adjusting the flow of coating glass in which the adjustments are automatically implemented at periodic intervals to adjust the inherent delays and transient conditions in the dynamics of flow of glass.

The apparatus for forming a stream of plywood has an inner core glass surrounded by an outer cladding glass, and includes at least a first hole for receiving the core glass from a first source. At least one second hole is below vertically spaced and aligned with the first hole, and is surrounded by a chamber communicating with the second hole through a gap between the first and second holes. A discharge tube delivers coating glass from a second source through a tube to the chamber so that the glass flows by gravity from the first and second sources through the holes to form the plywood current. In accordance with one aspect of the present invention, the flow rate of glass through the coating glass source or second, is measured and compared with one or more pre-set thresholds or limits. The flow rate of the coating glass from the second source to the chamber surrounding the holes is adjusted when the flow rate through the second source leaves the desired flow. For example, when the flow exceeds a desired upper limit or threshold, the flow is automatically reduced. On the other hand, if the flow falls below a desired lower limit or threshold, the flow is automatically increased. In this way, the desired ratio of coating glass to core glass is maintained automatically.

In the preferred embodiment of the present invention, the coating glass is delivered through a discharge tube having a lower opening in the discharge tube and a flow control tube disposed within the discharge tube for movement to and from the opening of the discharge tube so as to selectively open and close the opening. The discharge tube is coupled to an electric motor that is driven by electronic circuitry, which automatically responds to the speed of the glass flow within the glass discharge tube of coating, to selectively operate the motor and restrict flow through the motor. opening of the discharge tube. The movement in the coating glass flow control tube is preferably activated only at periodic intervals, so as to adjust inherent delays associated with changes in the glass flow through the system. The glass flow rate is preferably measured periodically and averaged over the measurement range in order to accommodate the transient conditions. More preferably, the flow control tube moves to and from the discharge tube opening, a predetermined distance after each measurement interval within which the average glass flow velocity exceeds or falls below the flow threshold limit. wanted. This is achieved in the preferred embodiment of the invention by the use of a stepper motor, and by providing the stepper motor with a predetermined number of pulses corresponding to the predetermined desired incremental travel distance in the discharge tube.

In accordance with another aspect of the present invention, a method for supplying a glass stream includes the step of supplying the glass from an intermittent glass hopper through a furnace, to a discharge pipe having an opening through it. from which the glass stream flows by gravity. The flow rate of the glass from the intermittent glass hopper through the furnace is measured, and the flow velocity from the discharge pipe opening is thus controlled to maintain the flow rate from the intermittent glass hopper through the furnace within the pre-established limits. The flow rate of glass through the discharge tube opening is controlled by positioning a tube within the discharge tube for movement to and from the opening, and controlling the position of the tube with respect to the discharge tube opening . The latter is most preferably accomplished by coupling the tube to an electric motor, and activating the motor to move the tube to and from the discharge tube opening in order to maintain the flow rate of glass through the oven within preset limits . The preferred implementation of this aspect of the invention is in the method for forming a plywood glass stream wherein the flow rate of the coating glass is measured from the intermittent coating glass hopper through the coating glass furnace, and the flow rate of glass through the coating glass discharge tube is automatically controlled as well to maintain said flow above a preset limit.

BRIEF DESCRIPTION OF THE DRAWINGS The invention together with the additional objectives, features and advantages thereof, will be better understood from the following description, the appended claims and the accompanying drawing, which is a fragmentary elevational schematic diagram of a delivery system of glass according to a currently preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing illustrates a system 10 for supplying a stream of plywood. A first refining furnace 12 supplies the core glass to a discharge pipe 14, which has an opening 16 at the lower end thereof. The discharge tube 14 is surrounded by a protective enclosure 18, preferably constructed of a non-magnetic metal such as stainless steel. A pipe 20 controls the supply of the core glass from the discharge pipe 14 through the opening 16 to and through one or more of the first holes conveyed by an upper orifice ring 24 below the discharge pipe 14. A lower orifice ring 26 carries one or more second holes positioned below the hole (s) of the ring 24 and axially aligned therewith. The second orifice is surrounded by an annular chamber 30 which is formed between the orifice rings 24, 26. The chamber 30 communicates with the second orifice by means of a lateral space or recess between the orifices. The annular chamber 30 is coupled by a delivery tube 32 to the opening 34 at the lower end of a coating glass discharge tube 36. The discharge tube 36 includes a delivery control tube 38, and is coupled to the oven Refining glass coating 40 of a coating glass furnace 41. The coating glass furnace 41 receives the coating glass from an intermittent glass hopper 43. The delivery tube 32 is heated by resistance by electronic control devices. 42, to maintain the flow of the coating glass to the chamber 30. As described, the system 10 in FIG. 1 is essentially the same as described in the above-noted European applications. The first of such applications is directed in particular to the construction of a coating glass delivery tube 32, while the last of such applications is directed in particular to the construction of orifice rings 24, 26. U.S. No. 4,740,401, also assigned to the assignee thereof, describes a system for delivering a coating glass stream in which an intermittent glass hopper delivers coating glass to an associated furnace and refining furnace of coating glass.

The delivery control tube of the coating glass discharge tube 38, has an upper flange or flange that is carried on a flange surrounding an opening in an annular tube holder 48. The tube holder 48 is mounted on a frame of support 50, which is coupled to a movable support bracket 52. A bevel gear is mounted on the support 48 to rotate the support and the flange 38 about the central axis of the tube. The flange of the tube is held against the flange of the support 48 by means of angularly spaced fastening clamps mounted on the support. This mechanism for mounting tube 38 is the same as that shown in U.S. Pat. No. 4,514,209, assigned to the transferee thereof, to which reference may be made for a more detailed description.

The support bracket 52 engages a helical or planetary gear 56 with an arrow 58. The arrow 58 is connected via a coupling 60 and an arrow 62 to a tube height actuator 64. The actuator 64 preferably comprises an electric motor of gradual speed responsible for introducing pulses for the rotary arrow 62, through a predetermined angle or pitch for each input pulse. The actuator 64 is also coupled to a wheel 66 for manual rotation of the arrow 62. A glass level probe 68 is coupled to the control screen 70 in the refining furnace 40 to supply an electrical output signal indicative of the level of coating glass in the refining furnace 40 and therefore the inflow rate through the furnace 41 from the hopper 43. This signal is fed to a coating glass level control 72, which drives the intermittent hopper -43, to provide a desired glass flow rate. The level control 72 also supplies a control circuit 74 with an output indicative of the flow rate of the coating glass. The control circuit 74 obtains an average flow rate reading (typically in tons / day) and feeds this signal to a controller 76. The function of the controller 76 is to drive the tube height pulse actuator 64, while limits the speed or frequency at which adjustments are made. The controller 76 receives the upper and lower limits 78 by linking a desired glass flow rate, and may also drive a display 80 to display the control and operation parameters to an operator, such as the flow rate of the coating glass. , the position of the tube 38 with respect to the opening of the discharge tube 34, and the flow limits established by the operator input 78.

In operation, the tube 38 is first adjusted, either manually by means of the wheel 66 or electronically by means of the actuator 64, to a desired initial spacing of the lower end of the tube 38 from the outlet opening of the discharge tube 34. The glass is then fed from the hopper 43 through the furnace 41 to the discharge pipe 36, and from the discharge tube 36 through the tube 32 to the orifice rings 24, 26 for the formation of a stream of plywood. After the flow conditions are stabilized, the electronic control devices 74 automatically begin to take the input flow measurement readings from the sensor 68. The electronic control devices 74 average a plurality of flow measurement readings over intervals. newspapers to eliminate the effects of transient flow variations. These average flow readings are compared to the maximum desirable flow rate set at 78. As the coating glass flow current wears, the flow rate of coating glass begins to increase. When this flow rate reaches the upper limit set at 78, the electronic control device 76 automatically transmits a set of number of pulses to the stepper motor of the actuator 64, so as to decrease the lower tube 38 a predetermined distance. For example, if gear set 56 is such that one turn of arrow 58 is equal to a fall of 0.071 cms. of tube 38, corresponding to a gear ratio of 35 turns for every 2.54 cms, an input arrow speed of 2.5 rpm for two seconds, you will obtain a downward movement of 0.0051 cms. of the tube 38 towards the opening of the discharge tube 34. This position is then maintained for another interval, preferably in the order of about thirty minutes, to provide a sufficient delay by the changes in the flow dynamics of the glass, to work through the glass delivery system. Various flow measurement readings are then taken again and averaged, and the tube 38 then moves a prespecified distance (0.0058 cm in two seconds in this example) towards the discharge tube opening 34, if the measured flow still exceeds the desired flow. This process is repeated until the glass flow from the intermittent glass hopper 43 through the furnace 41, is within the desired flow limits, after which the flow is continuously observed until further adjustments are needed.

If the measured flow falls short of the desired lower flow limit, the tube 38 can be increased and the process repeated. Each reduction in the coating glass flow will reduce the amount of glass flow within a mass of plywood. The overall weight of the glass gobs is maintained by controlling the flow velocity of the core glass, using conventional weight control techniques for glass masses.

It may also occur that the measured flow decreases below the desired lower limit set at 78, for example, due to a substantial decrease in ambient temperature. If this occurs, a process that is the inverse of that described above takes place, with the control tube rising an increase, the average flow readings taken after an interval, and an additional movement implanted if necessary. There will be a sufficient space between the upper and lower limits set at 78 (around the desired nominal flow) so that the control tube does not release excessively.

It is noted that with respect to this date, the best method known to the applicant to carry out the invention is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property

Claims (13)

1. An apparatus for forming a plywood current having an inner core glass surrounded by an outer facing glass, the apparatus includes means for delivering the core glass from a first source through a first hole, means for forming a second hole vertically spaced below and aligned with the first hole with a chamber surrounding the second hole, and communicating with the second hole through a gap between the first and second holes, and means for supplying coating glass from a second source to the chamber so that the glass flows by gravity from the first and second sources through the holes to form the plywood glass stream, characterized in that the means for delivering the coating glass further comprise: means for measuring the flow rate of glass within the second source, means for comparing the flow rate to a desired flow , and means for automatically adjusting the flow rate of the coating glass from the second source to the chamber when the flow velocity within the second source moves away from the desired flow.

2. The apparatus according to claim 1, characterized in that the means for supplying the coating glass comprises a discharge tube for receiving the coating glass and having a lower opening and a flow control tube disposed inside the tube. of discharge for movement towards the opening, for restricting flow through the opening, and wherein the means for adjusting the flow rate of the coating glass comprises means for moving the tube with respect to the opening when the flow rate within from the second source moves away from the desired flow.

3. The apparatus according to claim 2, characterized in that the means for moving the tube comprise an electric motor, means that operatively couple the electric motor to the tube and response means for comparing the means for operating the motor.

4. The apparatus according to claim 3, characterized in that the comparison means comprise means for comparing the flow velocity to the desired flow in first periodic intervals, and wherein the response means for the comparison means comprise means for moving the tube one predetermined distance to the opening when the flow rate of the coating glass moves away from the desired flow after each first interval.

5. The apparatus according to claim 4, characterized in that the comparison means comprise means for averaging the glass flow rate within the second source at second periodic intervals smaller than the first intervals and means for comparing the average flow velocity of glass inside the second source to the desired flow after each second interval.

6. The apparatus according to claim 5, characterized in that the electric motor comprises a stepper motor, and wherein the response means for the comparison means comprise means for transmitting a predetermined number of pulses to the stepper motor corresponding to the travel from a predetermined distance in the tube.

7. The apparatus according to any of the preceding claims, characterized in that the second source includes a glass intermittent hopper, a furnace and a glass refining furnace, and wherein the measuring means measure the flow rate of glass from the hopper Intermittent glass through the oven inside the refining oven.

8. The apparatus according to any of the preceding claims, characterized in that it further comprises means for establishing limits above and below the desired flow, wherein the comparison means comprise means for comparing the flow velocity measured to the limits, and wherein the means adjustment means comprise means for moving the tube towards the opening when the measured flow exceeds the limit above the desired flow and means for moving the tube away from the opening when the measured flow is less than the limit below the desired flow.

9. In a method for forming a plywood glass stream in which the glass of the first and second sources is supplied to a pair of aligned holes, so that the glass of the second source forms a coating around the inner glass core of the first source, the improvement for controlling the thickness of the coating characterized in that it comprises the steps of: (a) supplying the glass to the source from the intermittent glass means, through a furnace to a discharge pipe having an opening through which the glass flows by gravity to the orifices, (b) measure the speed of the glass flow from the intermittent glass media through the oven and (c) automatically control the flow rate of glass through the glass. opening in order to maintain the flow rate of glass measured in step (b) between the preset limits.

10. The method according to claim 9, characterized in that step (c) comprises the steps of: (cl) supplying means in the discharge tube for selective opening and closing of the opening, (c2) selective coupling of the means of opening and closing an electric motor, and (c3) selectively activating the motor to maintain the glass flow rate measured in step (b) between the preset limits

11. The method established according to claim 10, characterized in that step (c3) comprises the steps of: (c3a) comparing the flow rate of glass measured in step (b) to the pre-established limits at periodic intervals, (c3b) activate the motor to move the selective opening and closing means, to close the opening when the glass flow rate exceeds one of the limits, and (c3c) activate the motor to move the selective opening and closing means to open the opening when the flow rate of glass is less than the other of the limits.

12. The method according to claim 11, characterized in that steps (c3b) and (c3c) comprise the step of activating the motor to close or open the opening by a predetermined amount when the flow rate of glass exceeds a limit or is less than the other limit.

13. The method according to claim 11 or 12, characterized in that step (c3a) comprises the steps of averaging the glass flow over periodic intervals, and comparing the average flow of glass with the limits.