FI93203B - Device for bending glass sheets - Google Patents

Description

93203

Device for bending glass sheets. - Anordning för böjning av glasskivor.

The present invention relates generally to an apparatus for handling glass-5 sheets, and more particularly to an apparatus for heating and bending glass sheets.

One process that has been successful in making bent, tempered glass sheets, such as those commonly used in glazing for automobiles and the like, is the horizontal compression bending technique. This technique generally involves heating pretreated flat glass sheets to their softening or bending temperature by transferring them on a roller conveyor through a heating furnace, bending the heated sheets to a desired curvature or shape between a pair of complementary molds .

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It is to be understood that the glazing formed by the above process must be bent into well-defined shapes depending on the appearance and size of the openings to be glazed and the overall style of the vehicles in which the glazing is to be installed.

In addition, glazing must be properly tempered to increase its resistance to damage from shocks and, in the event of breakage, to break into relatively small harmless pieces as opposed to large, sharp-pointed, potentially dangerous pieces that would otherwise result from untempered glass sheets breaking. In addition, bent and tempered glazing must meet restrictive optical requirements that are free from surface defects and optical distortions that would interfere with clear visibility through them.

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Probably one of the most significant factors in meeting all the above requirements lies in heating the sheets to the optimum temperature level during the heating step to bring the glass sheets 5 to a suitable state for further processing. If the heated plate leaves the heating furnace, for example at a relatively cool temperature, it is not soft enough for proper and correct bending. In addition, it does not maintain the required heat required for the next 10 hardening. On the other hand, if the plate exiting the furnace is overheated, it becomes highly flexible, resulting in a loss of deformation control and a tendency to deviate from the desired shape beyond the strict tolerances shown. Overheating also tends to lower the surface quality of the final product due to thermal defects, rollers, point recesses and the like. With the optimum temperature range over which the sheets must be heated for satisfactory further processing being easily calculated, problems are encountered in uniformly achieving this desired temperature level 20 and maintaining multiple glass sheets within such a range in mass production operations. This is due to the inherent, albeit gentle, temperature variation resulting from the uneven heat production of the heating elements, both by the gas heating and electric heating elements, inside the furnace and by other external sources, ·. which affect the temperature of the heating atmosphere. In all cases, it has been found that the temperatures of successive plates leaving the furnace, as monitored by an advanced temperature measuring device, vary repeatedly and sometimes from plate to plate 30.

• «: Attempts have been made to solve this problem by varying the heat input to the heating elements according to the deviations of the glass temperature from the desired level.

35 However, these attempts have not been entirely satisfactory, due to the delayed effect of the heat input, i.e. time delay before the set heat

Il, 93203 3 the input is sufficiently reflected in the heating atmosphere and directed to the advancing glass sheets. Other attempts include manually adjusting the conveyor speed to compensate for temperature variations. However, it is practically impossible to manually make the necessary adjustments accurately in a minimum time due to human error and / or miscalculations, thus seriously undermining the efficiency of mass production operations. In addition, the complete concentration and constant control required of the user contributes significantly to fatigue, further increasing the potential for human error and poor judgment.

An attempt to control the temperature of glass sheets is disclosed in U.S. Patent No. 4,071,344. This patent discloses a method and apparatus for controlling the temperature of glass sheets passing through an oven by automatically changing the heat exposure time of the sheets in accordance with temperature deviations from the desired level observed in the heated glass sheets exiting the oven. The plates are supported in a substantially horizontal plane and moved in a substantially horizontal path through the heating furnace at a preselected speed. The individual temperatures of the given sets of heated glass sheets leaving the oven are measured and the average temperature deviations of the sets are determined: from the desired temperatures. The speed of the glass sheets in the oven is adjusted according to the amount of average temperature deviation from the desired temperature to change the time the sheets passing through the oven are exposed to heat and thus to change the duration of the rate change according to the average temperature deviation from the desired temperature.

The present invention relates to an apparatus for treating glass sheets 35, including a heating operation and a bending operation. The device is particularly useful for the production of laminated glazing, such as the windscreens of vehicles 4,922,203. The device controls the heating station and the bending station to allow continuous processing of glass sheets of different thicknesses and compositions.

The device according to the invention is characterized by the things set forth in the characterizing part of claim 1.

One or more sensors are used to identify each glass sheet before it enters the oven at the heating station. The glass plate is conveyed through the oven by a series of conveyors that are speed-controlled to determine the heating time. In addition, the last or more furnace compartments are provided with a plurality of strip heaters and associated thermocouples, each connected to one of the plurality of temperature controllers. The strip heaters extend in the direction of travel of the plates and are positioned across the width of the adjacent furnace. The set temperature of each controller can be adjusted to generate the desired amount of heat on the glass sheet in the area in question. Thus, for example, additional heat may be provided in the plate 20 in an area where a relatively large or complex bend is formed.

In the bending position, the distance between the upper and lower molds must be adapted to accommodate plates of different thicknesses. Example 25, which is a relatively thin glass, requires less. compression than a thicker plate. The present invention provides means for indexing a male mold member with respect to the closed position of a female mold member to achieve such a compression difference.

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Conveyor cycle speeds, temperature controllers and indexing ·; the road members can be operated by a computer, which in addition receives signals from the plate sensors as well as actual speed and temperature signals to coordinate the continuous processing of the glass sheets. The value of the setpoint signals for speed, temperature, and mold space is stored in a computer related to the individual parameters of the glass sheets. One or more of the 93203 5 sensors senses the individual parameters of the plates protruding into the oven, and the computer responds by changing the setting values, if necessary, to process the plates in order.

5 In the accompanying drawings:

Figure 1 shows a glass diagram of a glass sheet processing apparatus according to the present invention in a vertical diagram.

Fig. 2 shows a vertical side view of the bending station of the device of Fig. 1.

Figure 3 is a cross-sectional view of the bending station taken along line 3-3 in Figure 2.

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Figure 4 is a bottom plan view of the strip heater assembly of the device of Figure 1;

Fig. 5 is a schematic view of an embodiment of a control system for the device shown in Fig. 1.

Figure 6 is an alternative embodiment of a control system for the device shown in Figure 1.

Figure 7 is a flow chart of the method implemented by the present invention.

According to the present invention there is provided an apparatus for bending glass sheets, the apparatus comprising an oven, a bending station, a conveyor for passing glass sheets through the oven and said bending station and a differential heating system comprising a plurality of heating means mounted in the oven to heat associated conveyor glass sheets. the apparatus 35 further comprising: means for generating actual temperature signals representative of the actual temperature value of each of said heating elements; means for generating temperature setting signals representative of the desired temperature-5 value of each said heating member; and means connected to said heating means and to both said means for generating signals and responding to said actual temperature signals and said temperature setting signals to control heat production of each said heating means 10, characterized by: means for identifying at least one identifying parameter indicating the type of glass plate to be conveyed to generate set signals to change the value of at least one of said temperature set signals based on the detected at least one identifying parameter.

Figure 1 shows a glass sheet processing device 11 including a continuous conveyor system 12 for supporting a plurality of glass sheets 20 for moving them in a substantially horizontal plane. The conveyor system 12 passes the sheets 13 through a heating station 14 which includes an oven 15 for heating the sheets to their softening point or bending temperature. The conveyor system 12 also extends through the bending station 16 to bend the heated plates 13 to the desired curvature. Not shown is a conventional tempering station with cooling means for rapidly lowering the temperature of the reheated plates to produce the desired tempering of the bent glass after bending.

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. · The furnace 15 is of the tunnel type with a pair of side walls 17 (only one is shown), a roof 18, a base 19, an inlet end wall 20 and an outlet end wall 21 defining a heat chamber 35. The heating chamber 22 can be heated in any desired manner by suitable heating means. such as gas burners or electric heating elements 93203 7 (not shown) placed on the ceiling and side walls of the furnace 15. Such heating means are suitably controlled by conventional means (not shown) to achieve the desired temperature at various points in the heating chamber 22.

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The conveyor 12 is formed by a conveyor to transport a plurality of periods of continuous sheet 13 in the direction of the arrow 23 nusaseman the heater 14 and the bending station 16. The plurality of plates 13 are individually loaded on the longitudinally spaced conveyor rollers 24 of the first feed conveyor 25 10 and supported thereon in a substantially horizontal plane. Any of a number of conventional alignment devices (not shown) can be used to properly align the plates 13 for travel through the heating station 14 and the bending station 16.

The feed conveyor 25 supplies the plates 13 to an acceleration conveyor section 26 adjacent the inlet end wall 20 of the furnace 15. The accelerator conveyor 26 extends into an inlet opening 27 formed in the inlet end wall 20. The second acceleration conveyor 28, located inside the furnace 15, extends from the opening 27 to a conveyor section 29 extending through the center of the chamber 22. Next, the plates 13 are conveyed through a conveying cycle defined by two acceleration conveyors 25 30 and 31. The conveyor 31 extends into an outlet opening 32 formed in the outlet end wall 21. Adjacent the outlet opening 32, outside the furnace 15, is a bending conveyor section 33 which conveys the plates 13 through. Finally, the plates 13 are transferred to the tempering station conveyor section 34, which feeds the plates 30 to the tempering station (not shown).

«The speed of movement of the discs 13 along the conveyor system 12 is controlled by a motor controller 35. Each conveyor cycle can be controlled separately from the speed of the discs 13 so that when the discs are fed by the feed conveyor 25, the processing speed can be increased by the accelerator conveyor sections 26 and 28. at a speed determined by the conveyor cycle 29. The speed of movement of the plates 13 can then be again increased in the acceleration cycles 30 and 31 for feeding to the bending station 16. The sheets are transferred through the bending station 16 by a conveyor cycle 33, 5 at a substantially higher speed than through the furnace 15 to minimize the heat losses that occur during this transfer. The conveyor section 34 operates at a substantially slower speed than the bending station conveyor section 33 to ensure adequate exposure of the plates to the cooling medium.

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The conveyor section 26 includes a plurality of rollers 24 mounted at opposite ends on bearing pieces (not shown) disposed on opposite sides of the conveyor system 12. The conveyor rollers 24 15 of the conveyor section 26 are driven together via an endless conveyor chain 36 from a reduction gear mechanism 37 connected to a speed controlled power supply or electric motor 38. Accordingly, the conveyor rollers 24 of the conveyor section 29 are driven by a drive chain 42 coming from a reduction gear mechanism 43 connected to the motor 44; the rollers of the conveyor section 30 are driven by a chain 45 of a reduction gear mechanism 25 connected to the motor 47; rollers of conveyor cycle 31. · driven by a drive chain 48 from a reduction gear mechanism 49 coupled to a motor 50; the rollers of the conveyor section 33 are driven by a chain 51 from a reduction gear mechanism 52 coupled to the motor 53; and the rollers of the conveyor section 34 are driven by a chain 54 30 from a reduction gear mechanism 55 coupled to the motor 56.

The speed-controlled electric motors 38, 41, 44, 47, 50, 53 and 56 "are all operatively connected to the motor controller 35 by control line 57, 58, 59, 60, 61, 62 and 63, respectively. Thus, when the speeds of each conveyor cycle are established, the motor controller 35 can adjust the speed of each motor proportionally in response to a change in the speed of any conveyor cycle.

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The bending station 16 includes an upper male mold member 64 and a lower female mold member 65 having opposing complementary shaped surfaces that conform to the shape of the bent sheets of curvature and are mounted for relative movement away and away from each other. The male mold member 64 has a downwardly directed, substantially convex forming surface 66 and is mounted above the rollers 24, while the female mold 64 is positioned below the conveyor rollers 24 and mounted to move vertically toward and away from the male mold member 64. To allow the female mold member 65 to move above the level of the conveyor rollers 24 to raise the plates 13 above said level, such member is formed of a plurality of segments 67 mounted on the carriage 68 and spaced far enough apart to allow segments 67 to pass between adjacent rollers 24. The segments 67 form a composite, ring-type structure having a substantially concave forming surface 69 complementing the forming surface 66 of the male mold member 64.

The support 68 is movable vertically by a fluid actuator 70 having a suitable piston rod 71 to raise and lower the female mold member 25 65 attached thereto. The mold member 65 is moved between a lower position: below and above the upper position of the conveyor rollers 24. The mold member 65 moves the heated glass sheet 13 from the conveyor rollers 24 and presses them against the male mold member 64 between the complementary forming surfaces 66 and 69, thereby shaping the glass sheet to the desired curvature. The male mold member 64 can also be • mounted, if desired, for vertical movement by hanging it on the piston rod 72 of the fluid actuator 73.

The temperature of each glass sheet immediately prior to the first processing step is the most critical factor in achieving the desired degree of uniformity of shape and tempering in glass sheets treated in accordance with the compression bending operation described above. For example, the sheets must be heated to a temperature range to make them flexible enough to give the desired shape when bent and to retain a sufficient amount of heat for subsequent hardening without overheating to such an extent that the deformation control is lost, so that after bending the sheets are depressed and also sensitive. markings and additional distortions on the conveyor rollers.

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Although the optimum temperature range in which the heated plates should be treated can be easily calculated and / or determined experimentally, difficulties have been encountered in achieving this optimum temperature range uniformly for several successively heated plates. This is due to several factors, including the degree of furnace load, the heat flows inside the furnace, and, for example, variations in the outlet temperatures of different gas burners or resistors, due to variations in the heat source medium or resistor encountered in the electric power input. If the glass sheets 13 are all of the same type, the desired optimum glass temperature can be achieved automatically by adjusting the speed of the conveyor cycle inside the heating furnace 15 to increase or decrease the heat exposure time of the sheets according to the temperature deviations observed in the sheets leaving the oven. When the measured temperature falls below the desired value, the speed of the conveyor cycle is reduced to increase the heat exposure time of successive glass sheets passed through, and in contrast to the measured temperature being greater than the desired value, the speed of the conveyor cycles is increased to reduce the heat exposure time. Such a control system is disclosed in U.S. Patent No. 4,071,344.

However, additional problems arise when bending glasses for laminated products and / or products with large curvatures at short distances. For example, it is more efficient and results in a better product when two glass sheets intended to be joined together as a windshield are processed one after the other when they are transported by means of a conveyor system. Often, the two glass sheets are of different thicknesses and may also have different compositions. In addition, it is desirable to heat the local areas of the glass sheet to higher temperatures in order to properly form highly curved surfaces when the glass is, for example, of the wraparound type of the vehicle.

The present invention provides means for heating and bending various glass sheets together on a production base. In Fig. 15, one or more conventional sensors 74 are located adjacent to the conveyor sections 25 and 26 to identify the identifying parameters of the glass sheets 13. Sensor 74 is shown connected to generate a sensor signal to timers 75 along line 76. For example, the sensor 74 may represent a thickness sensor 20 that produces a sensor signal indicating which of the two thicknesses of glass sheets is just going to the furnace 15. The timer 75 may be set to match the thickness signal received on line 76 to generate a bending position indexing signal 77 for motor 78.

The motor 78 is connected to an indexing system 79, which: will be explained in more detail in connection with Figures 2 and 3.

The indexing system 79 moves the upper mold member 64 between an upper position that produces less compression for forming and to reduce transverse bending in the thinner glass sheets 13, and a lower position to apply more pressure to the thick glass sheets. The indexing mechanism 79 may be mounted on the upwardly facing surface of the upper mold member 64. The timer 75 may also generate a rate control signal on line 80 to the controller 35. The controller 35 may then adjust the speed of the conveyors 28, 29, 30 and 31 to change the speed of the glass sheets 13 through the furnace 15 for more or less heat depending on the thickness of the glass.

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The present invention also provides means for generating differential heat, i. varying the amount of heat applied to the desired area of the glass sheet 13. Oven 15 is typically divided into heating zones, each equipped with its own temperature control system (not shown). However, such an oven is incapable of imparting different heat to certain areas of the glass sheet. As shown in Figure 1, the plug wall 81 extends downward from the inner surface of the roof 18 of the furnace 15. For example, if the furnace 15 has twelve heating zones, the plug wall can be placed between zones 9 and 10. The plug wall 81 extends across the furnace between the side walls 17. The heat strip assembly 82 is suspended below the lid 18 and cooperates with the side walls 17, the lid 18, the outlet end wall 21 and the plug wall 81 to form a cavity 83 in the top of the furnace 15. Cooling air is provided in the cavity 83 by an intake fan 84 through a plurality of pipes 85. Air is removed from the cavity 83 by a second fan 86 connected to an outlet pipe 87 extending through the cover 18 adjacent the outlet end wall 20. The inlet fan 84 and the outlet fan 86 provide a slightly positive pressure in the cavity 83. The cooling air prevents the ambient air from becoming too hot due to the heating strips 82. In addition, a plurality of thermocouples 88 may extend through the lid 18 of the furnace 15 to measure the ambient air temperature in the cavity 83. When the air temperature exceeds a predetermined limit, e.g., 316 ° C (600 ° F), the lid 18 suspended by a plurality of chains 89 may be raised. allow heat to escape and lower the ambient temperature.

In use, the glass sheets 13 arrive at the inlet of the oven 15 by a feed conveyor 25. An alignment device (not shown) may be arranged to grip the leading edge of each sheet and align it properly for passage 35 through the oven 15. When the cursor releases the plate 13, it is transferred to the first acceleration conveyor, the conveyor section 26, and delivered to the inlet 27 of the second acceleration conveyor ti.

13 93205, conveyor cycle 28. These two conveyor cycles 26 and 28 increase the speed of the glass sheets by approximately 150 inches / minute, which is typically the speed of the conveyor cycle 29. The third acceleration conveyor cycle, conveyor cycle 30, and the fourth acceleration-5 conveyor cycle, conveyor cycle 31, further increase the speed of the glass sheet 13 through the last travel portion in furnace 15. For example, cycles 30 and 31 may increase speed from approximately 150 inches / minute to a maximum speed of 300 inches / minute. However, if the glass sheets 13 are windshields of 10 vehicles, the desired maximum speed is in the range of 1100 to 1800 inches / minute. As the glass sheets exit the furnace 15 through the outlet 32, they move to the conveyor section 33, which accelerates the speed of the glass sheets by approximately 400 inches / minute before the sheets hit the alignment stops 15 to place the sheets in the bending station 16.

As shown in Fig. 2, the glass plate 13 rests on the conveyor rollers 24 of the bending conveyor section 33. The leading edge of the glass plate 13 engages an alignment stop mechanism 101 extending 20 upward from the carriage 68 between a pair of adjacent conveyor frames 24. The carriage 68 and the fluid actuator 70 are mounted on a substantially horizontally extending support plate 102, which in turn is supported above a surface 103, such as a building floor, by four vertically extending pillars 104. A pair of pillars 104 are located on each side of the conveyor section 33. When the medium actuator 70 is used, the lower female mold member 65 moves upward to extend the segments 67 between the conveyor rollers 24 so that the concave forming surface 69 engages the lower surface of the glass plate 30.

The indexing system 79 and the upper male mold member 64 are supported by a substantially rectangular frame structure formed of four box beams 105.

A pair of box beams 105 extending transversely to the direction of movement of the conveyor system 12 are supported below a pair of substantially horizontally extending U-shaped beams 14 93203 106 by substantially vertically extending guides 107. The beams 106 extend between the upper ends of the associated pairs of pillars 104 and are attached to those pillars located on opposite sides of the conveyor. The actuator support beam 108 extends between the beams 106 and is attached to them at its opposite ends. The medium actuator 73 is attached to the support beam 108 and extends downwardly therefrom. Thus, the medium actuator 73 moves the upper male mold member 64 and the indexing system 10 downward toward the top surface of the glass sheet 13 to secure the convex forming surface 66 thereto.

In some laminated windshields, a sheet of relatively thin glass is laminated to a sheet of substantially thicker glass 15. In terms of production efficiency and quality, it is desirable to process both types of plates alternately. However, it is desirable to apply less pressure to the molding of the outermost sheet to reduce cross-bending and provide better nesting during lamination. The indexing system 79 is used to index the upper male mold member 64 upwardly from its desired position to bend thicker glass sheets 13. For a typical windshield, the indexing distance can be 1.016 mm (0.040 ").

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Referring to Figures 2 and 3, the indexing support plate 109 extends horizontally below the box beams 105 and is attached at its opposite ends to a pair of box beams 105 extending substantially in the direction of travel of the conveyor system. A fifth drawer beam 110 is attached to the top surface of the plate 109 and is also attached at opposite ends to the same pair of drawer beams 105. The lower end of the piston rod 72 is attached to a second support plate 111 extending between the same pair of drawer beams 105 and attached to opposite drawbars . The four threaded arms 112 extend downwardly through the support plate 109 and are secured at their lower ends

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93203 on the upper surface of the upper male mold member 64. Each of the arms 112 is part of a screw auxiliary device 113 mounted on the upper surface of the plate 109. The screw auxiliaries 113 are driven simultaneously by the electric motor 114 mounted on the upper surface of the plate 109. The electric motor 114 drives the output pulley 115, which in turn drives the pulley 116 via a belt (not shown). The pulley 116 is attached to the end of the common drive shaft 117. The drive shaft 117 drives a pair of reversing switches 118, which in turn drive one of 10 pairs of drive shafts 119. Each of the driven shafts 119 drives a pair of screw auxiliaries 113. Thus, when the motor 114 is operated, the upper male mold member 64 raises or lowers the support pin 109 to provide less, or correspondingly more, pressure to bend the glass sheet 13.

The heating strip assembly 82 is shown in more detail in Figure 4. The heating strip assembly 82 includes a first section 121 positioned adjacent a plug wall 80 (not shown) 20. The section 121 consists of a plurality of heating strips. For example, the 20 strips may extend in the direction of movement of the glass sheet 13, as shown by the arrow 23. The first heating strip 124 is located at one edge of the first section 121. Additional strips are arranged side by side and at regular intervals 25 across the width of the section 120 and terminate on the opposite side of the strip 125. Each of the strips may be provided with heating means of conventional shape, such as a nickel wire resistance heater. Each of the strips is further provided with a thermocouple, such as a thermo member 126 adjacent the heating strip 124 and a thermocouple 127 adjacent the heating strip 125. The second or middle section ♦ 122 also includes 20 heating strips, such as a heating strip 128 adjacent one edge of the section 122. The heating strip 128 is provided with an associated thermocouple 129, like 35 all the heating strips in the section 122. Finally, the third section 123 also includes 20 heating strips, such as the heating strip 130 adjacent one of its edges. Each of the heating strips 16 93203 in the section 123 is provided with an associated thermocouple, such as a thermocouple 131 connected to the heating strip 130. A typical glass sheet 13 is centered between the heating strips 124 and 125. By controlling the amount of heat arranged in the heating strip in each section 121, certain areas of the glass sheet 13 can be heated to different temperatures.

Figure 5 shows a control circuit for a differential heating system including the heating strip assembly of Figure 4. Power from the building power supply (not shown) is made available in the supply line 130. The line 132 is connected to the input side of the isolation transformer 133, the output side of the transformer is connected to the line 134. The line 134 is connected to the input of the disconnect switch and circuit fuses 135. The output of the switch and fuse 135 is connected by line 136 to a thyristor (SCR) power controller 137. The output of controller 137 is connected by line 138 to an associated heating strip, such as heating strip 124. Temperature controller 139 has 20 outputs connected by line 140 to power controller 137 input. The thermocouple 126 connected to the heater 124 is connected by a wire 141 to the inlet of the temperature controller 139. Computer 142 generates a temperature setpoint signal at the output to line 143 connected to controller 139. Computer 25 also generates other output signals to lines 144 connected to output devices 145 that include temperature controllers for other heating strips. In addition, computer 142 receives input signals over line 146 from input device 147. Output devices 145 and input devices 146 are described in more detail below.

• «• The temperature controller 139 may be a Eurotherm 808 D1 temperature controller manufactured by Eurotherm of Reston, 35 Virginia. A separate temperature controller 139 is provided for each heating strip, and the computer 142 may be programmed to generate temperature setting signals for each heating strip 17 as required for differential heating to achieve a bending shape on the glass sheet 13. For example, if sharp bends are to be made on opposite sides of the glass sheet 13, one or more heating strips placed directly above the path of movement of the bend receiving area may be set for a higher temperature than the heating strips on both sides to facilitate bending of the glass.

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An alternative differential heating system is shown in Figure 6. Controller 137 receives power on line 136, generating power on line 138 to control heater 124. Thermo member 126 transmits an actual temperature signal via line 141, which line is connected to the input of analog / digital interface 151. Terminal 151 has an output connected by line 152 to the setpoint input of controller 137. Wires 153 connect the inputs and outputs of computer 142 to the outputs and inputs of interface 151, respectively.

The temperature controller 139 of Figure 5 may be implemented in software connected to a computer 142. In addition, other inputs and outputs of interface 151 are connected by wires 154 to bus 155. Wires 153 and 154 represent connections to other heating strips. Correspondingly, the inputs and outputs of the computer 142 are connected to bus 155: * by lines 156. The disk sensor 74, for generating the sensor signal, is also connected to bus 155 by line 76. Speed controller 157 is connected to bus 158 to generate actual speed signals and receive speed setpoints. 30 signals. The speed controller 157 represents the controller 35 in Figure 1. The compression index 79 has inputs and outputs connected to bus 155 on lines 159 to generate actual station signals and receive indexing signals. The compression index 79 controls the motor 114 by generating an index-35 ring signal along line 160. The cooling unit 161 has inputs and outputs connected to bus 155 via lines 162 to generate a high temperature signal and to receive 18 93203 control signals. The cooling controller 161 controls the operation of the fans 84 and 86 along lines 163 and 164, respectively. The plate sensor 74, speed controller 157, compression index 79, and cooling controller 161 represent the output devices 145 and 5 input devices 147 of Figure 5. Figure 7 shows a flow chart for operating the differential heating systems of Figures 5 and 6. The control program starts at step 171 and proceeds to instruction base 172, where the program stores the setpoint temperature values "S (N)" for each heater 124.

10 The program proceeds to instruction base 173, where the heater identification variable "N" is set to zero. The program then proceeds to instruction base 174, where the occurring "N" value is incremented by one and the temperature "T (N) M associated with heater 124 is read from associated thermocouple 126. The program proceeds to terminal 175, where the actual temperature signal value" T (N) " compared to the setpoint temperature signal value “S (N).” If the temperature values match, the program branches off at the “Y” point to the second reasoning point 176. At the decision point 176, the program checks whether all temperature-20 Ia values are checked “N = 60?” If all values have been checked, the program branches to "Y" back to instruction set 173, where the process is repeated, if not all values are checked, the program branches back to instruction set 174 at "N", where the "N" value is incremented by one. 25 If the value of the actual temperature signal "T (N)" does not correspond to the value of the temperature signal of the setpoint "S (N)", then the program branches from reasoning point 175 non- "The program" adjusts the output signal for the setpoint "N" in a manner that tends to drive the actual temperature of the heater 124 as measured by the thermocouple 126 toward the desired setpoint temperature. The program then returns to the reasoning:: * entry 176. The flowchart shown by symbols 171-177 can be programmed in the computer 142 of Figure 5 to generate a temperature setpoint signal on line 143 to temperature controller 139 associated with heater 124 and lines 144 associated with other temperature controllers. The flowchart can also be implemented with the data of Figure 6.

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19 95203 in machine 142 to generate control signals on wires 153 to analog / digital interface 151 to control heaters 124.

The computer 142 of Figure 6 may also be programmed to interact with devices connected to the bus 155. For example, the program may start at source 178 and proceed to instruction base 179 to check the Senso signal received from disk sensor 174. The program proceeds to reasoning 180 and determines if the signal interruption from the plate sensor 74 is "INT 10?", Indicating that the glass plate under examination is different from the last glass plate being examined. If the disks are different, the program branches to "Y" in instruction base 181, where the timer is set. If the answer is no "N", the program branches around the instruction set 181. Program 15 continues from instruction set 181 or non-branch to instruction set 182, where the program reads actual rate signals representing the rates of different conveyor cycles.

The program exits instruction base 182 at reason 183 to verify the actual speed signal with the conveyor system speed setpoint signal. If the actual speed corresponds to the speed of the setpoint, the program branches to "instruction" 184 in the "Y" position. If the actual speed does not match the speed of the setpoint, the program branches from 25 reasoning points 183 to "instruction set 185" at point "N", where · the setpoint is adjusted to the actual speed. value. The program exits instruction set 185 to instruction set 184, where the temperature signals from the cooling system are read. The program then proceeds to reasoning 30 186, where the actual temperature in the cavity 83 is compared to the maximum temperature "X". If the maximum temperature is exceeded,. . the program branches at yes to the "Y" instruction base 187, where glass plate processing is stopped, and the program then moves to stop 188.

If the maximum temperature in the cavity 83 is not exceeded, the program branches from reasoning 186 at point "N" 35 20 93203 to instruction base 189, where the compression index 79 is checked. The program proceeds to reasoning 190 from instruction base 189 to determine if indexing is required in bending position 16. If the timer set in instruction 181, has been completed and the indexing system 79 has been set up for another type of glass sheet, so that the program branches at the "Y" point to the instruction set 191, where the indexing system 79 is started. The program then proceeds to instruction set 192. If the timer has not expired or the indexing system is set for the approaching glass plate, the program branches off from reasoning 190 at non-"N" and proceeds directly to instruction set 192. Command base 192 controls the computer to generate speed and temperature setpoint signals to control the conveyor cycle motor speed controller and heaters, respectively. The program then branches back to instruction set 179.

Although the program for computer 142 is shown in one format in Figure 7, it can be implemented in a number of different formats. An important consideration is that the inputs of the actual temperature signal from thermocouple 126, Senso signal from plate sensor 74, actual speed signals from speed control 157, positioning signals from compression index 79, and high temperature signal from cooling control 161 are read periodically and outputs are adjusted as needed. The values of the speed and temperature setpoint for different types of glass plates can obviously be stored in a computer. Referring to Figure 4, the glass sheet 13 may require considerable bending in areas heated by a pair of strips 193 and 194 adjacent the side edges of the glass sheet 13. Thus, the computer 142 would store a pair of setpoints •: value for heating strips 193 and 194 for one glass sheet of a pair of laminated glass sheets and store a second set of setpoints for heating strips 193 and 194 for the second sheet of glass sheets 35, which may vary in thickness and / or composition relative to the first glass sheet. The plate sensor 74 detects identifying parameters indicating the type of glass plate li 93203 21 that protrudes into the furnace and signals the computer to change the setpoints for heating strips 193 and 194 within a suitable time corresponding to the glass plate distance through the furnace. In addition, the computer can store different speed setpoint groups for conveyor cycle speeds to also implement differential heating between successive glass sheets by adjusting the travel time through the oven 10.

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A

Claims (16)

An apparatus for bending glass sheets, comprising an oven (15), a bending station (16), a conveyor (12) for passing the glass sheets through the oven and said bending station and a differential heating system comprising a plurality of heating means (82) mounted in the furnace to heat the areas adjacent to those conveyed by the conveyor through the furnace. said device further comprising means (126, 127, 129, 131) for developing real temperature signals which represent the respective real temperature values of said heating element; means (42) for developing temperature set values which represent respectively the desired temperature value of the heater; and means (139) connected to said heating means and both said means (11) for developing signals and reacting for said real temperature signals and said temperature setting signals for controlling respectively said heating means's heat production, characterized by: means (74) for identifying at least one individualizing parameter indicating the type of glass plate transmitted on the conveyor and coupled to said means for developing said temperature setting signals to convert at least one temperature setting signal value on the basis of at least one observed individualizing parameter. Device according to claim 1, characterized in that said plurality of heating means comprise electric resistance heating flaps (124, 125, 128) which extend longitudinally in the direction of advance of the glass sheets (13) and positioned opposite each other. over the conveyor's forward direction. to 27 27 93203 Device according to claim 1 or 2, characterized in that said means for developing real temperature signals comprises a plurality of thermocouples (126, 127, 129, 131), said thermocouple developing one of said real temperature signals, connecting to one of said said heating element (124, 125, 128). Device according to any one of claims 1-3, characterized in that said means for developing temperature control signals comprises a computer (142) with values for said temperature control signals in connection with values corresponding to at least one observed in this stored individualizing parameter. 5. Apparatus according to any of claims 1-4, characterized in that said control means comprise several temperature control means (139), said respective temperature control means being coupled to one of said heating means. Apparatus according to any of claims 1-5, characterized in that said identification means comprises a disk sensor (74) positioned adjacent the entrance opening of the conveyor located in the oven to identify each of the at least one individualizing glass panels mentioned in the oven. 25 parameter. • 7. Device according to claim 6, characterized in that the disc sensor (74) comprises means for identifying the thickness of the glass disc (13) as at least one individualizing parameter. > · * Apparatus according to claim 6, characterized in that the disc sensor (74) comprises for identifying characteristics which indicate the composition of the glass disc (13) as at least one said individualizing parameter. 9 7? Π 3 28. w “u J 9. Device according to claim 6, characterized in that the disc sensor (74) comprises means for identifying the color of the glass disc (13) as at least one said individualizing parameter. 5 10. Device according to claim 6, characterized in that the disc sensor (74) comprises means for identifying the shape of the glass disc (13) as at least one of the individualizing parameters. 10 Device according to any one of claims 1-10, characterized in that it further comprises: indexing means (79) coupled to the identification means (74) for controlling the pressure exerted by the bending station on the glass sheets, based on the identified at least one pair. -metern. 12. Device according to claim 11, characterized in that the bending station comprises an upper male molding means 20 (64) and a lower female molding means (65) which engage the respective glass and upper surfaces of the bending station and the indexing means (79). controls the distance between the upper male mold member and the lower female mold member. 13. Apparatus according to claim 12, characterized in that the indexing means (79) comprise several screw auxiliary devices (113) connected to the upper male molding means (64) and the bending station's body and connected to the driving means (114), while said driving means are connected to the identification means. Means (74), for sliding the upper male mold member (64) into the retaining member and controlling the distance between the upper and lower mold members. Device according to any one of claims 1-13, characterized in that it further comprises means (35) for developing a real velocity signal representing the real leaking speed of the glass slab through the oven, and said means for developing the temperature control signals develop at least one speed control signal, which represents the desired glass disk advancement rate through the furnace (15) and respond to the real speed signal and the speed control signal to convert said set signal value based on the observed at least one parameter value. Device according to any one of claims 1-14, characterized in that it further comprises means for developing a high temperature signal, which represents the ambient atmosphere temperature next to the heating means and which is functionally coupled to the control means for switching off said heating means and interrupt the treatment of the glass panels. 16. Apparatus according to claim 14 or 15, characterized in that said means for developing the speed-setting signal further develops several speed-setting signals, each of which represents the desired speed value for the function of said conveyor function. 25 ««