CS237310B2 - Drop detection device for glass forming machine - Google Patents

Abstract

The invention relates to a drop detection device in a glass forming machine that includes drop distributor for forming glass objects and control circuit connected with this forming device. According to the invention is at the path of progress of droplets a drop sensor is disposed between the device, and between circuit for changing the start time in the control circuit and detector is connected between the drop sensor droplet circuit. The drop sensor contains phototransistor.

Description

BACKGROUND OF THE INVENTION The present invention relates to a device for detecting drops in a glass forming machine comprising a drop distributor, a glassware forming apparatus and a control circuit associated with the glassworking apparatus.

In a glass forming machine, known as a sectional machine, each individual station includes a plurality of means for performing a predetermined sequence of steps in time relationship to form the glassware. The forming device is usually driven by pneumatic motors, controlled by valve blocks, which in turn are controlled by a rotating timing drum. The glass melts and forms into droplets which are led to the individual stations by the drop distributor. Each machine station generates glassware from the droplets, whereupon the glassware is placed on a shutdown for ejection onto a scraper conveyor. The timberman removes the glassware into the tunnel cooling furnace for annealing and cooling, or any other processing.

Each station is operated in a predetermined sequence with a relative phase difference in order to receive the droplets from the droplet distributor in a specified sequence. When one of the stations receives a drop from the droplet distributor, another of the stations supplies the finished glass product to the conveyor and the other stations perform different of the forming steps. In addition, two molds may be provided at each station so that the drop is received in a first mold, called a blank mold, for the initial step of forming the preform, followed by converting the preform into a second mold, called the final mold, to finalize or blow the article. . Because each mold may have more than one cavity, each machine station operates simultaneously on a plurality of drops to form glass articles.

Whether a timing drum or an electronic control system is used to determine the timing of individual stations, in the prior art machines the timing of the stations is synchronized with the timing of the droplet feeder and the droplet distributor. Not only do the stations work on the phase difference to each other in order to receive the droplets in a specified sequence, but also the phase differences must be pre-set to differences at the time of droplet drop to individual stations usually located in a single line along the conveyor. the same given distance from the drop feeder.

The purpose of the invention is to increase the efficiency of the glass forming machine by timing the glassware forming cycle from the actual arrival of the molten glass drop to the mold.

Another object of the invention is to increase the capacity of the glass forming machine by timing the glassware forming cycle since the registration of the last drop of molten glass that enters the multi-cavity mold.

Finally, it is an object of the invention to increase the capacity of a sectional glassware forming machine by adjusting the phase differences between the timing cycles of the stations for the actual arrival of molten glass drops into the molds.

The principle of the invention is that a drop sensor is provided at the droplet travel path into the forming device, and a drop detection circuit is connected between the start time change circuit in the control circuit and the drop sensor.

According to a preferred embodiment, the drop sensor comprises a phototransistor.

According to another embodiment of the invention, the droplet detection circuit comprises a comparator and a threshold signal source connected to the comparator input, the second input of which is connected to the drop sensor output.

According to another embodiment of the invention, the drop sensor comprises a housing in which a central cavity is formed and an opening connecting the central cavity to the exterior of the housing, wherein a phototransistor is housed in the central cavity.

The aperture preferably has a diameter of about 3.18 mm and a length of 12.7 mm.

In an embodiment where the glassware machine has a mold with at least two cavities, the drop detection circuitry is connected to the control circuit and the last drop registration circuit is connected to the droplet detection circuit outputs and additionally has an output connected to the control circuit input.

According to another embodiment of the invention, the first drop detection circuit is located at the first mold cavity, the second drop detection circuit is located at the second mold cavity, and the last drop registration circuit is connected to the outputs of the first and second drop detection circuits by its inputs.

According to yet another embodiment of the invention, the OR-gate selection circuit is connected to the last drop registration circuit, the input of which is connected to the output of the second drop detection circuit, and the output is connected to the NAND gate input included in the last drop registration circuit.

Suitably, a first monostable multivibrator input sensitive to the falling edge of the first drop detection pulse is connected to the first drop detection circuit output and a second monostable multivibrator responsive to the drop edge of the second drop detection pulse input and its first and second outputs In the second multivibrator, the NAND gate is connected via its inputs.

In this embodiment, the OR gate is connected with its one input to the output of the second monostable multivibrator and another input to the selection circuit.

Feedback resistors are expediently connected to the threshold signal source, which are also connected to the comparator input.

The invention relates to an apparatus for detecting the presence of a drop of molten glass as it enters a mold in a glassware forming machine. A hot drop emits radiation

S in the visible to infrared spectrum, and this radiation is received by the phototransistor. The phototransistor reacts by generating an electrical signal that compares to the threshold voltage to produce a detection signal. The detection signal can then be used to adjust the timing of a single station according to the actual droplet arrival in the mold, and not to the droplet formation time, including the estimated mold advance time, as was the case with prior art machines. When the mold comprises two or more cavities, the detection signals from the illustrated detector for each cavity may be blocked to indicate when the last drop has arrived.

The invention will be described by way of example with reference to the drawings.

Giant. 1 is a block diagram of a two station sectional machine comprising drop detection circuits of the invention.

Giant. 2 is a plan view of one of the drop sensors of FIG. 1.

Giant. 3 is a diagram of a drop detection circuit according to the invention.

Giant. 4 is a diagram of a drop detection circuit for a multi-cavity mold of the invention.

Giant. 5 is a block diagram of another embodiment of a sectional two station machine comprising drop detection circuits of the invention.

FIG. 1 is a block diagram of a two-station glassware forming machine incorporating the drop detection circuitry of the present invention. The individual stations, i.e. the first forming device 11 and the second forming device 12 receive the molten glass droplets from the droplet distributor 13, which in turn receives the droplets from the droplet dispenser (not shown). The droplet distributor 13 is mechanically driven by a drive motor 14, which is connected to a variable frequency power source generated by the converter 15. The droplet feeder is driven in a similar manner. The drive frequency is controlled to determine the rate at which the droplets are formed and distributed to the individual forming devices 11, 12.

The first and second molding devices 11, 12 are associated with separate valve blocks 16 and 17, respectively. Each valve block 16, 17 has valves connected to control a plurality of glassware forming devices at an associated individual station. The valves in the valve blocks 16, 17 are actuated by solenoids which are controlled by a machine control circuit 18 which determines the timing of the forming steps in accordance with a predetermined sequence of these steps. The control circuit 18 receives information in sequence of steps and time between steps from a source (not shown), for example from control switches or from a computer program.

The position sensor 19 is mechanically coupled to the drive motor 14 and produces signals representing the relative position of the droplet distributor 13. A similar position sensor (not shown) is provided for the drop dispenser. Since the formation of the drop depends on the rotational position of the droplet feeder drive motor, and the distribution of any drop is dependent on the rotational position of the drop distributor drive motor 13, the respective position sensors produce signals indicating when the drop is formed and to which station it is assigned.

The machine control circuit 18 also receives a signal from the 21-hour pulse source, which constitutes a reference variable for timing the machine cycle and the sequence of steps. Usually the machine timing is expressed in degrees so that one machine cycle has a 360 ° interval. The cycle for each station is also 360 °, but the cycle cycles for the stations will be over 100% from the start of the machine cycle by a different number of degrees to compensate for the time difference in drop delivery to each station. The glass forming machine shown in FIG. 1 is described in detail in U.S. Pat. No. 4,007,028, issued February 8, 1978.

FIG. 1 also shows a drop sensor 22 and associated drop detection circuit 23 according to the invention. The drop sensor 22 is located at the process path between the droplet distributor 13 and the first forming device 11 and in the vicinity of the mold opening (not shown). When the drop comes into the mold, the sensor 22 responds to the presence of the drop by sending a sensing signal to the drop detection circuit 23. The drop detection circuit 23 compares the size of the sensing signal with the size of the threshold signal to generate a detection signal to the machine control circuit 18 when the drop is detected. The control circuit 18 can then set the start of the glass forming cycle in the first forming device 11 relative to the droplet entering machine cycle. The drop sensor 24 and the drop detection circuit 25 are adapted for the second forming device 12 to adjust the start of the glass forming cycle for this forming device 12 in a similar manner.

Figure 2 is a partial cross-sectional plan view of the drop sensor 22 of Figure 1 to illustrate the phototransistor. the drop sensor 22 has a housing 31 that is provided with a first elongated hole 32 that connects one end of the housing 31 to a central cavity 33. In the central cavity 33 a phototransistor 34 is disposed at the inner end of the first opening 32. The standard plug-in connector 36 is connected to the housing 31 at the outer end of the second longitudinal bore 35 and has a central pin 37 that projects into this bore 35. The phototransistor 34 has a pair of leads, namely a collector lead and an emitter lead that is connected to the connector 36, namely a collector lead to the pin 37 and an emitter lead to the sleeve 38. The second aperture 35 has a larger diameter than the first aperture 32 as well as the central cavity 33 to facilitate connection of the lead to the connector 36 before the connector 36 is connected to the housing 31.

The housing 31 is typically formed of a non-aqueous material, such as a phenolic material. The light-sensitive base of the phototransistor 34 is positioned so as to be directed along the longitudinal axis of the first aperture 32 so that the first aperture 32 forms a "window" through which the phototransistor 34 registers a passing hot drop of molten glass. Typically, the first aperture 32 has a diameter of 3.18 mm and a length of 12.7 mm to reduce the field of view, making the phototransistor more sensitive, so that the front edge of the drop is sharply detected and additionally provides some protection against foreign matter coming from the air and arising from the glassware forming process. However, since a source of compressed air is available to control the pneumatic motors of the machine, this source can be used to create an air stream to flush the first opening 32.

Figure 3 shows a schematic diagram of the drop sensor 22 and droplet detection circuit 23 of Figure 1. The phototransistor 34 is connected to a pin 37 of the connector 36, which in turn is connected to the comparator input 41 via a capacitor 42. The phototransistor 34 is connected to a sleeve 38, which in turn is connected to the ground potential of the system. Resistor 43 is connected between a positive polarity power source (not shown) and pin 37 to limit the current flow through the phototransistor 34. Resistor 44 is connected between the power source and comparator input 1. The second comparator input 2 is connected to the node of the resistor pair 45, 46 by Resistors 47. Resistors 45, 46 are connected between the energy source and the ground potential. The output 3 of the comparator 41 is connected to the output line 48 of the drop detection signal, to the power source through the resistor 49 and to the input 2 of the comparator 41 through the resistor 51.

When no drop is present, the phototransistor 34 is disconnected and both sides of the capacitor 42 will be at the power supply voltage which is also connected to the comparator input 1. Resistors 46, 45 act as a voltage divider to create a threshold voltage at comparator input 2. If comparator input 1 is an inverting input and comparator input 2 is a non-inverting input, comparator 41 generates a signal at or near the ground potential of the system because the power source voltage at comparator 41 input 1 is greater than the threshold voltage at comparator 41 input 2 When a drop is detected, the phototransistor 34 is closed. Since the voltage at the capacitors cannot change instantaneously, the input 1 of comparator 41 will also be close to the system ground potential. The comparator 41 thus changes its output signal to the power supply voltage and the resistor 49 creates a current path to drive the circuit connected to the output line 48, which is at the power supply voltage.

While the drop passes around the sensor 22, the capacitor 42 will be charged at the power supply voltage through the resistor 44 to ensure that the comparator 41 will flip back to or near the ground potential of the system. However, the length of time the drop passes the detector is typically less than the charge time constant for the capacitor 42. Therefore, the phototransistor 34 turns off at the rear edge of the drop, and the magnitude of the comparator 41 input signal exceeds the threshold for comparator 41 In this way, the drop detection signal generated on line 48 is in the form of a rectangular pulse, the magnitude of which is equal to or close to the voltage of the power source, and whose duration is determined by the time the drop requires to pass through the sensor window. Resistor 47 and resistor 51 provide positive feedback to comparator input 2 forming a deadband between the voltage levels at which the comparator 41 engages the output states. This zone of insensitivity, or hysteresis, prevents any cscilations that might occur during the transition between the output states.

In the circuit of FIG. 3, the phototransistor 34 may be a TI-L66 transistor manufactured by Texas Instruments, and the comparator 41 may be a LM 339 comparator manufactured by National Semiconductor. Typical values for circuit components are 120 kiloohms for resistor 43 and 220 kiloohms for resistors 44 to 47, 33 megaohms for resistors 45 and 49, 13 kiloohms for resistor 46,

3.3 megohms for a resistor of 51 and 5 microfarads for capacitor 42. The positive polarity power supply is 15 volts.

Fig. 4 shows a schematic diagram of a drop detection circuit according to the invention for a plurality of cavities. The detection circuit 61 represents the drop sensor and the drop detection circuit as shown in FIG. 3. The rectangular drop detection pulse generated by the detection circuit 61 forms the input to the monostable multivibrator 62. 0 ", such as the drop edge trailing edge pulse, by creating a rectangular pulse of predetermined duration to OR 63 summation gate input 1. OR 63 summation gate generates a value of" 0 "at output 3 if both pairs of inputs 1 and 2 are on value "0", and produces "1" on output 3 if one or both of the outputs is "1". The OR 63 gate input 2 is connected to the selector line 64 and the OR 63 gate output 3 is connected to the NAND 65 gate 1 inlet. The gate 65 creates a value of "0" if all of its inputs are at "1" and generates a value of "1". “For all other input signal combinations. The gate output 4 of the NAND 65 is connected to the input of the monostable multivibrator 66, the output of which is connected to the output line 67 of the last drop registration signal.

The second drop detection circuit 68, which is similar to the detection circuit 61, has an output which is connected to the input of the second monostable or multivibrator 69, the output of which is connected to the input gate OR 71. The OR gate has an input 2 connected to the selector line. 72, and an output 3 coupled to the gate 2 of the NAND 65. The detection circuit 73, also similar to the detection circuit 61, has an output coupled to the input of the monostable multivibrator 74 whose output is coupled to the input 3 of the NAND 65.

The circuit of FIG. 4 is suitable for use in conjunction with a mold having one, two or three cavities. Obviously, this circuit can be expanded if the mold is to have more than three cavities. If the mold has three cavities, a select signal "0" is connected to each of the select lines 64, 72 to open the summing gates OR 63 or 71. The select signals "0" can be generated by any selection means, for example switches connected to the earth potential. system or computer. If no drop is detected, all the outputs of the detection circuit 61, 68 will be at "0" as well as the outputs of the associated monostable multivibrators 62, 69, 74, so that "0" will appear at the inputs to the NAND 65. The NAND 65 in the " .1 & quot ^; .

When each drop enters the mold cavity, the associated drop detection circuit B1, 68, 73 generates a rectangular detection signal. The associated monostable multivibrator 62, 69 is triggered at the trailing edge of the drop, and if the pulse duration of the multivibrator 62, 69, 74 exceeds the time between detecting the trailing edge of the first drop entering the mold and the trailing edge of the last drop entering the mold. at "1" to change the signal at NAND 65 gate output 4 from "l" to "0". When the multivibrator assigned to the first drop detector stops operating, the associated NAND 65 gate output returns to "0" and its output 4 returns to "1" to form a rectangular pulse "0". The multivibrator 6S responds to the rear strand of pulse "0" by producing a signal "1" indicating that the trailing edge of the last drop entering the mold has been removed and that all three drops are in the mold.

If one of the mold cavities is not operative or if the mold has only two cavities, the associated selector leads 64, 72 may have a signal "1" connected to each other to generate a value of "1" at the assigned NAND gate input.

65 to open the NAND 65 to detect drops entering both cavities. If two of the mold cavities are inactive or if the mold has only one cavity, the two selector lines 64, 72 may have a signal '1' connected to each other to make the NAND 65 accessible for detecting a drop entering the one cavity. The select signals "1" can be generated by any suitable means, such as switches connected to a positive polarity power supply or a computer.

Fig. 5 is a block diagram of another embodiment of a sectional machine with two stations comprising drop detectors according to the invention. The elements indicated by the same reference numerals as in FIG. 1 are similar to the corresponding members shown in FIG. 1. However, the position sensor 19 of FIG. 1 is removed. The clock pulse source 21 is replaced by a timing circuit 81. Therefore, the timing circuit 81 responds to the pulse frequency supplied by the inverter and generates a timing signal to the machine control circuit 18 to synchronize the sectional machine cycle with the droplet distributor 13. For a contemplated example of a two station machine, the station cycles can be set with a 180 ° phase difference in a 360 ° machine cycle, and the start of each station cycle can be adjusted for the actual drop coming into the mold.

The invention therefore relates to a drop detection circuit for generating a detection signal in response to the presence of a molten glass drop in a forming apparatus in a glassware forming machine. The machine comprises means for distributing molten glass droplets at a predetermined speed from the droplet source, means for generating glass articles in a predetermined and predetermined sequence of droplet steps taken from the distributing means and a control device responsive to the droplet distributing speed to cyclically control the forming apparatus operation in cycles of timed, predetermined sequence of steps. The control device responds to the detection signal by initiating the next cycle of the time predetermined neck sequence. When the molding apparatus comprises a multi-cavity mold, the droplet detecting device is assigned to each cavity, and a device responsive to the simultaneous generation of all detection signals produces a detection signal for the last drop directed to the control device to initiate the next cycle.

However, the invention is not limited to the embodiments described and illustrated.

Claims (11)

Subject A device for detecting drops in a glass forming machine, comprising a drop distributor, a glassware forming apparatus and a control circuit associated with said glassware forming apparatus, characterized in that at the droplet path to the glassware forming apparatus (11, 12), a drop sensor (22) is provided, wherein a drop detection circuit (23) is connected between the start time changing circuit in the control circuit (18) and between the drop sensor (22). A drop detection device according to claim 1, characterized in that the drop sensor (22) comprises a phototransistor (34). The drop detection device of claim 1, wherein the drop detection circuit (23) comprises a comparator (41) and a threshold signal source coupled to the comparator input (41), the second input of which is coupled to the sensor output (22). drops. 4. A drop detection device according to claim 2, wherein the drop sensor (22) comprises a housing (31) in which a central cavity (33) is formed and an opening (32) connecting said central cavity (33) to the outside. a housing (31), wherein a phototransistor (34) is disposed in the central cavity (33). 5. A drop detection device according to claim 4, wherein the opening (32) has a diameter of about 3.18 mm and a length of 12.7 mm. 6. The drop detection apparatus of claim 1, wherein the glass forming machine has a mold with at least two cavities, wherein the drop detection circuit (61, 68, 73) and the last registration circuit are connected to the control circuit (18). The droplet is connected with its inputs to the droplet detection circuit outputs (61, 68, 73) and furthermore has an output connected to the input of the control circuit (18). 7. The drop detection apparatus of items 1 and 6, wherein the glass forming machine has SUMMARY OF THE INVENTION A mold having at least two cavities, characterized in that the first drop detection circuit (73) is located at the first mold cavity, the second drop detection circuit (68) is located at the second mold cavity, and the last drop registration circuit is connected to the outlets and first and second drop detection circuitry (73, 68). 8. The droplet detecting device of claim 1, wherein an OR gate (71) is connected to the last drop register circuit, the input of which is connected to the output of the second drop detection circuit (68), and the output is connected to the input. a NAND gate (65) included in the last drop registration circuit. 9. A drop detection device according to claim 7, wherein the first drop of the first drop monostable multivibrator (74) sensitive to the falling edge of the pulse of the first drop detection circuit (73) is connected to the output of the first drop detection circuit. a second monostable multivibrator (69) is connected to the second drop circuit circuit (68) responsive to the fall edge of the second drop detection circuit (68) and connected to the outputs of the first and second multivibrator (74, 69) by its inputs: NAND gate (65) . A drop detection device according to claim 9, characterized in that the OR gate (71) is connected via its one input to the output of the second monostable multivibrator (69) and another input to the selection circuit. Drop detection device according to claim 3, characterized in that resistors (47, 51) are also connected to the threshold signal source, which are also connected to the input of the comparator (41).