Abstract:
A programmable control signal generator controls the overall speed of an I.S. machine, the timing of sequential functions of each individual section, and the relative phasing of the IS machine sections. A time-based drive signal, derived from the time base signal of the programmable control signal generator, is applied to a stepper motor which is coupled to a gob feeder and plunger mechanism and a conveyor mechanism through respective gear reducers. The pulse repetition rate of the drive signal is controlled manually from an operator&#39;s speed control station or automatically from a computer to establish and vary the machine speed. The programmable control signal generator also provides a timing signal, coordinated with the drive signal, to time the sequential functions of the sections as a function of the number of elapsed time increments into which a machine cycle is divided. The timing signal has a pulse repetition rate which is preferably a calculated ratio of the repetition rate of the drive signal. In addition, the programmable control signal generator provides a cycle reference signal, coordinated with the drive signal, to control phasing of the sections. The reference signal has a pulse repetition rate which is preferably a calculated ratio of the repetition rate of the timing signal.

Description:
BACKGROUND OF THE PRESENT INVENTION 
     This invention relates to a programmable timing controller for synchronizing the operation of one or more sections of a glassware forming machine or other plural-sectioned machine with one another and with machine components common to all individual sections. 
     The individual section glassware forming machine (&#34;IS machine&#34;), which is well known in the art, comprises a plurality of individual sections. The individual sections perform sequentially timed functions in synchronism with one another in a phased relationship. Gobs of molten glass are acquired in sequence from a shear and feeder mechanism and as one of the individual sections is receiving a gob, another individual section is delivering a finished glass container to a conveyor system. At the same time, other individual sections are engaged in various functions that are intermediate between the receiving of a gob and the delivering of finished glass container to the conveyor. Such a glassware forming machine is disclosed in Ingle U.S. Pat. No. 1,911,119. 
     It is necessary to accurately control the timing of various IS machine operations. It is well known to time the mechanism operations common to all of the individual sections of an IS machine by a drum having cam members, called buttons, movably attached about its surface. The drum is rotated by a motor which may, also, drive the gob feeder mechanism. The cam members selectively activate valves in a valve block to control fluid pressure to cylinders which operate the various operating components of each of the individual sections of the IS machine. This arrangement is, also, disclosed in Ingle U.S. Pat. No. 1,911,119. 
     However, the process of positioning the cams on the timing drum to implement or modify function timing sequences is inexact, cumbersome if not dangerous and time consuming. Such a timing apparatus further to prone to mechanical wear leading to irregularities in the forming operation, resulting in unacceptable glass containers. Consequently, substantial efforts have been made to develop an electronic timing and synchronizing control system to help overcome such drawbacks. Such an automatic control system is disclosed in Quinn et al U.S. Pat. No. 3,762,907 and Kwiatkowski et al U.S. Pat. No. Re. 29,642. The control system disclosed in these patents include a machine cycle position indicating means which in the embodiments disclosed was the shaft for driving the gob shears. In addition a timing means was responsive to the cycle position indicator for generating a digital signal indicative of the machine cycle position. In the embodiments disclosed, this was a shaft encoder. Thus in the embodiments disclosed, an electro-mechanical drive system was provided. The appreciable amount of jitter experienced with the electro-mechanical shaft encoder, sometimes as high as five or ten percent, adversely effects the accuracy of the timing controller and limits the operating speed. In a recently issued U.S. Pat. No. 4,145,204 to Farkas a control system is disclosed which also includes a cycle position indicating means and a timing means responsive thereto for generating a signal indicative of the machine cycle position. In Farkas the cycle position indicating means is the inverter which drives the motors and the timing means is a signal generator which is responsive to the output of the inverter. More specifically, in Farkas, a gob feeder and distributor supplies gobs to the individual sections at a predetermined rate proportional to the frequency of the power supplied by an inverter drive. A timing circuit is responsive to the frequency of the inverter output to generate clock signals which are applied to a machine control circuit for controllably actuating the functions of an associated individual section. The timing circuit also provides a timing reset signal to initiate the machine cycle. Accordingly, the machine speed, function timing, and cycle initiation are synchornized with one another, and the gob feeder and the gob distributor are phased (with reference to the reset signal) such that a gob is distributed to the individual sections at the required times in the machine cycle. More accurate control of the machine cycle is facilitated by providing a gob detector circuit and sensor, which detect the presence of a gob at the mold. Responding to the output of the gob detector circuit, the control circuit supplies a minor correction to the section timing, if needed. The Farkas apparatus includes a plurality of drive motors which must be phased with one another. 
     Reference also is made to commonly assigned copending U.S. application Ser. No. 281,466, of Haynes et al, filed July 8, 1981 which relates to a method and apparatus for glass factory control. The present invention can be conveniently utilized with the Haynes et al apparatus which includes a programmable apparatus responsive to the frequency of an oscillator for generating a synchronous timing signal at a frequency which provides 360 pulses per machine cycle. A timing reset signal for initiating the machine cycle is derived from the timing signal. The apparatus also generates a synchronous drive signal which is applied to an inverter system for controlling the speed of respective motors (gob distributor, shear, and conveyor motors in the Haynes et al apparatus). A feedback loop from the gob distributor motor to the inverter system enables proper control and stability. 
     There is thus still a need for an improved timing controller adapted for use in an IS machine (or in other types of machines having sequentially timed steps) which avoids jitter contaminated timing pulses and eliminates the need for plural mechanical drive motors and sensors and sensor detection circuitry. Further, there is need for such an improved timing controller to be programmable to automatically provide a machine speed setting and to dynamically vary that setting during operation. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention improves the accuracy of a machine timing controller and increases the maximum operating speed of a machine by eliminating use of known shaft encoders which produce outputs having jitter at high operating speeds. It also avoids the need for a plurality of motors to drive the mechanical operations of a machine and the need for sensors to improve the accuracy and phasing of the various forming operations in the individual sections of an IS machine. Furthermore, the present invention is programmable. 
     When adapted for use in an individual section glassware forming machine (IS machine), the present invention controls the speed of the IS machine and provides for the function timing and phasing of the operations of the individual sections of the IS machine relative to one another. A stepper motor drives a shear and feeder plunger mechanism and a conveyor mechanism through respective gear reducer means. The relative speed of the shear and feeder plunger mechanism and the conveyor mechanism are predetermined and established by the respective gear reducer ratios. The speed of the stepper motor is controlled by a pulse train, referred to herein as a drive signal, from a machine timing controller. The drive signal preferably is derived from the time base of the machine timing controller, but may be supplied by a variable frequency oscillator responsive to command signals. The pulse repetition rate of the drive signal is predetermined or controlled dynamically by the command signals issuing from an operator through a computerized speed control station or from a high-level computer assigned control for supervisory tasks over the entire glassware forming factory. 
     Typically, the functions performed by the components of the individual sections are timed according to a machine cycle divided into 360 one degree segments. Accordingly, the machine timing controller supplies a timing signal and a phase reference (cycle) signal. The timing signal is derived from the drive signal supplied to the stepper motor and is a programmed or predetermined ratio of the repetition rate of the drive signal. The reference signal has a repetition rate which is a function of the number of degrees into which a machine cycle is divided, and in the case of an IS machine one cycle pulse is generated for every 360 timing pulses. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features, and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, appended claims and the accompanying drawings. 
     In the drawings, where like numbers indicate like parts, 
     FIG. 1 is a block diagram of an exemplary embodiment of a glassware forming machine control system according to the present invention; 
     FIG. 2 is a flow diagram of a typical set of programmed steps that can be executed in a digital computer to generate suitable control signals according to the present invention; 
     FIG. 3 is of a programmable control signal generator a block diagram of a first exemplary embodiment suitable for use in the control system of FIG. 1; and 
     FIG. 4 is of a programmable control signal generator a block diagram of a second exemplary embodiment suitable for use in the control system of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the exemplary embodiment shown in FIG. 1, a programmable control signal generator 14 is responsive to instructions issued from a computer 10 and an operator speed control station 16 to provide several different types of signals for controlling the speed and function of an individual section machine (hereinafter &#34;IS machine&#34;). As is well known in the art, an IS machine comprises a plurality of individual sections (indicated herein by reference numeral 28(X) where X=1, 2, . . . , N; and N typically varies between 6 and 10). Each individual section 28(X) cyclically performs sequential timed functions. The cycles of the individual sections are related to one another, preferably by phase angles, for regulating production from the IS machine. For example, the cycles of the individual sections of a six-sectioned IS machine are preferably all mutually separated by sixty degree phase angles. Furthermore, the function timing and section phasing are preferably synchronized with the speed of the IS machine. Accordingly, it is necessary to supply a speed control (or drive) signal, a timing signal, and a phase reference signal to the control system of the IS machine. 
     The control system of an IS machine according to the present invention comprises the programmable control signal generator 14 coupled to an IS machine drive 8 through drive signal line 17 and to an IS machine timing controller 12 through timing signal line 25 and reference signal line 27. In operation, &#34;degree&#34; settings for the various functions performed by the section and section phasing information is controllably provided to the section controller 26(X) by the computer 10 along data line 11. As is well known in the art, each function of the section 28(X) is activated at a respective predetermined degree number. The degree settings for the various functions differ for different jobs and often during the same job depending on such factors as temperature and production speed. Section phase information also is controllably provided as necessary. Once established, section phasing information infrequently changes, but is affected by production requirements (i.e., the number of sections that are in service for a particular job) and the number of sections taken out of service, for example. Control signal information is provided to the programmable control signal generator 14 by the computer 10 and the operator speed control section 16. This information establishes the frequency relationships between the time base of the programmable control signal generator 14, the drive signal, the timing signal and the reference signal as described below. 
     The drive signal is applied to the stepper motor system 18 of the drive 8 through drive signal line 17 to operate and control the speed of the IS machine. The stepper motor system 18 comprises a stepper motor drive unit (not shown) which drives an electro-hydraulic stepper motor (not shown). The stepper motor system 18 drives the shear and feeder plunger mechanism 22, which forms and delivers gobs to the individual sections 28(X), through gear reducer 20. The stepper motor 18 also drives the conveyor mechanism 24 (including a pusher arm mechanism and a conveyor mechanism), which removes finished ware from the respective sections 28(X) of the IS machine, through gear reducer 21. The gear reducers 20 and 21 may or may not have the same gear ratios. Shear and feeder plunger mechanisms, conveyor mechanisms, stepper motors, and gear reducers are well known in the art. 
     The timing signal and the phase reference signal are applied to the section controllers 26(X) through timing signal line 25 and reference signal line 27, respectively. The section controllers 26(X) are parts of electronic control systems known in the art. For example, such electronic control systems are described in U.S. Pat. No. 3,969,703, issued July 13, 1976 to Kwiatkokwski et al (now U.S. Pat. Re. 29,642), incorporated herein by reference thereto. The section controller 26(X) controls the selective activation of the various glassware forming functions executed by the section 28(X) and the phasing of the operating cycle of the section 28(X). 
     The section controller 26(X) preferably operates relative to a 360 degree machine cycle, although other machine intervals could, of course, be utilized. Each degree interval of the machine cycle is represented by one pulse on timing signal line 25. Not only must the functions of the section 28(X) occur at the proper degree intervals, but the operating cycles of each of the sections 28(X) comprising the IS machine must occur in a phased relationship with one another. This phased relationship allows each of the sections 28(X) to operate essentially independently of one another while sharing a common shear and feeder plunger mechanism 22 and conveyor mechanism 24. Accordingly, each section controller 26(X) responds to the reference signal with its own correspondingly predetermined phase delay in accordance with the firing order information provided by the computer 10. Phased section operation is described in greater detail in, for example, the aforementioned Kwiatkowski et al patent. 
     In the presently preferred exemplary embodiment, the programmable control signal generator 14 is a programmable microprocessor capable of executing program steps such as those shown in FIG. 2. Suitable microprocessors are commercially available and include the model SBC 80/05 (Single Board Computer) manufactured by Intel Corporation. The time base of the programmable microprocessor is provided by an internal clock producing pulses having a predetermined recurrence rate. In the presently preferred exemplary embodiment, the time base pulses are counted to produce the drive signal, the drive signal pulses are counted to produce the timing signal, and the timing signal pulses are counted to produce the reference signal. The number of time base signal pulses that are counted to produce a single drive signal pulse is designated P D  ; the number of drive signal pulses counted to generate a single timing signal pulse is designated P T  ; and the number of timing signal pulses counted to produce a single reference signal pulse is designated P R . These parameters are calculated from several known constants and a single variable. The known constants are: 
     F, the frequency of the time base signal; 
     I, the number of degree intervals per machine cycle (360 degree intervals unless otherwise specified); 
     Q, the number of pulses required to effect one revolution of the stepper motor system 18; 
     R, the gear ratio of a selected gear reducer (in the presently preferred exemplary emobodiment, the gear reducer 20 driving the shear and feeder plunger mechanism 22). The single variable is designated T, the time desired for the completion of a full machine cycle. 
     In the presently preferred exemplary embodiment, the parameters P D , P T  and P R  are determined as follows: 
     
         P.sub.D =(F×T)/(Q×R)                           (1) 
    
     
         P.sub.T =(Q×R)/I                                     (2) 
    
     
         P.sub.R =I                                                 (3) 
    
     Although the drive signal is derived from the time base signal, the timing signal is derived from the drive signal, and the reference signal is derived from the timing signal in the presently preferred exemplary embodiment, it is to be understood that these are not the exclusive methods by which the signals may be derived. For example, the present invention also contemplates deriving all three signals directly from the time base signal pulses, in which case the following equations would apply: 
     
         P.sub.D =(F×T)/(Q×R)                           (4) 
    
     
         P.sub.T =(F×T)/I                                     (5) 
    
     
         P.sub.R =(F×T)                                       (6) 
    
     Other equivalent derivations are possible as should be apparent. 
     As shown in FIG. 2, generator 14 executes an initialization step 50 whereby all registers and the constants F, I, Q and R are initialized. The initialization step 50 is followed by an acquisition step 52, in which a value for the parameter T is acquired. Following the acquisition step 52, the values for the parameters P D , P T  and P R  are calculated in a calculation step 54. In the preferred exemplary embodiment, equations (1), (2), and (3) are used. 
     Once the calculation step 54 is executed, the drive signal, the timing signal and the reference signal are generated. The generator 14 waits until a time base pulse is received, as indicated by the decision step 56. Once a time base pulse is received, the time base pulse count is incremented by one, as indicated by the process step 58, and the number of counted time base pulses is compared to the value of parameter P D , as indicated by a decisional step 60. If no equality is found, the microprocessor again waits until a time base pulse is received, as indicated by the return arrow to step 56. If the time base pulse count is equal to P D , however, a drive pulse is generated, as indicated by a process step 62; the time base pulse count is initialized, as indicated by a process step 64, and the drive pulse count is incremented by 1, as indicated by a process step 66. The drive pulse count is compared to the value of the parameter P T , as indicated by a decisional step 68. If no equality is found, the microprocessor again waits for a time base signal pulse, as indicated by the return arrow to step 56. If the drive pulse count is equal to P T , however, a timing pulse is generated, as indicated by a process step 70; the drive pulse count is initialized, as indicated by a process step 72; and the timing pulse count is incremented, as indicated by a process step 74. The timing pulse count is then compared to the value of the parameter P R , as indicated by a decisional step 76. If no equality is found, the microprocessor waits for a time base pulse, as indicated by the return arrow step 56. If equality is found, however, a reference pulse is generated, as indicated by a process step 78; the timing pulse count is initialized, as indicated by a process step 80, and the microprocessor waits for a time base pulse, as indicated by the return arrow to step 56. In all the above cases, where a return arrow is directed to the decisional step 56, the microprocessor waits until a time base pulse is received and executes the process step 58 and the subsequent steps as described above. In this way, the drive signal, the timing signal, and the reference are generated. 
     Typical values for some of the known constants are as follows. Where the stepper motor system 18 requires 200 pulses per revolution, and the gear reducer 20 has a 18:1 ratio gear box, each machine cycle would require 3,600 drive pulses. Where I has the value of 360 degree intervals per machine cycle, ten drive pulses are counterd before a timing pulse is generated, and 360 timing pulses are counted before a reference pulse is generated. 
     Exemplary hardware embodiments are shown in FIG. 3 and FIG. 4. In FIG. 3, the generator 14&#39; is a programmable microprocessor comprising a time base signal generator 102 which is programmed to effect the operations represented by a computer logic circuit 100. As shown, an arithmetic unit 108 provides values for the parameters P D , P T  and P R  to respective comparators 106(1), 106(2), and 106(3). The values of the parameters P D , P T  and P R  are established according to equations (1), (2) and (3), the constant and variable values thereof being provided by computer 10 and station 16 (see FIG. 1). The time base signal generator 102 drives a counter 104(1), the output of which is compared to the value of P D  in the comparator 106(1). When a match occurs, a pulse is provided at the output of the comparator 106(1) and supplied as a drive signal to the drive signal line 17. The output of comparator 106(1) is also applied to a clear (&#34;C&#34;) input of the counter 104(1) to reset the counter 104(1). 
     Counter 104(2) receives the drive signal provided at the output of the comparator 106(1) to count the number of drive pulses. The output of the counter 104(2) is compared to the value of the parameter P T  in the comparator 106(2). When a match occurs, a pulse is provided at the output of the comparator 106(2) and supplied as a timing signal to the timing signal line 25. The output of the comparator 106(2) is also applied to a &#34;C&#34; input of the counter 104(2) to reset the counter 104(2). 
     Counter 104(3) receives the timing signal provided at the output of the comparator 106(2) to count the number of timing pulses. The output of the counter 104(3) is compared to the value of the parameter P R  in the comparator 106(3). When a match occurs, a pulse is provided at the output of the comparator 106(3) and supplied as the reference signal to the reference signal line 27. The output of the comparator 106(3) is also supplied to a &#34;C&#34; input of the counter 104(3) to reset the counter 104(3). 
     In the exemplary embodiment of FIG. 3, it will be appreciated that the combination of the counter 104(1) and the comparator 106(1) can be viewed as a ratio counter having the ratio P D  :1. Similarly, the combination of the counter 104(2) and the comparator 106(2) can be seen as the ratio counter P T  :1. Similarly, the combination of the counter 104(3) and the comparator 106(3) can be viewed as a the ratio counter P R  :1. Such an exemplary embodiment is shown in FIG. 4, where a generator 14&#34; comprises a P D  :1 counter 110, a P T  :1 counter 120, and a P R  :1 counter 130. The values of the parameters P D , P T  and P R  are determined by the counters 110, 120, and 130 respectively according to equations (1), (2) and (3) respectively, the constant and variable values thereof being provided by computer 10 and station 16. A time base signal generator 102 provides a time base signal to the P D  :1 counter 110. 
     While the present invention has been described in connection with what is presently thought to be the most practical and preferred exemplary embodiments, and in connection with several exemplary embodiments, it is to be understood that the present invention is not limited to such disclosed embodiments but, rather, is intended to cover all modifications and/or equivalent arrangements included within the spirit and scope of the appended claims. For example, the various timing signals may be separately derived from a common time base signal using independent channels of circuit components which are, of course, nevertheless still mutually synchronized by the common time base input. Accordingly, all such variations and modifications are intended to be within the scope of the following claims.