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Automatic Control in Forming and Finishing
AUTOMATIC CONTROL IN FORMING AND FINISHING
Gerald A. Jakes Reliance Electric Company Toledo, Ohio
Although the industry began applying large comex puters to the process before minicomputers were in existence, there are many reasons for applying the dedicated minicomputer even if a large process computer already exists in the plant.
ABSTRACT Great improvements have taken place in the manufacturing of glass in the last decade. These improvements have been largely mechanical in nature, having to do with upgrading of forming and finishing machinery to maximize production rates per present-day standards. Now is the time to concentrate on the application of electrical equipment to these new and redesigned machines.
centr al If an entire process line is run by a large central will computer, a malfunction in any section wi 1I cause the entire proces processs to go down. If one of a number of minicomputers fails, that portion of the process can be run in manual unti I the fault is corrected. The cost of the dedicated minicomputer is about equal to the required portion of the time shared computer.
The forming and finishing area of any glass plant is and should be coming under increased scrutiny by company management.
The programming minicomputer is simpler, Simpler, not conc ern hims elf with concern himself llarge arge process computer.
It is this area where most of the labor in a typical glass plant is found. Since glass has the lowest raw material cost of any basic material, any decrease in the labor content per fini shed piece makes the product increasingly salable in its traditional markets and opens up new markets based on continuing research and advancing technology.
and / or software package of a and/or because the programmer need other programs exi sting in the existing
The large computer can become the supervisory computer to one or more dedicated minicomputers. As such, it can command comman d the dedicated computers to perform predetermined major function s, as well as gather gath er data to functions, produce logs log s rel ated to production, inventory, downtime related and efficiency of the process.
Automatic control has been applied in the industry, but sporadically and generally not in the area of forming and finishing; am in the melting area and finishingj but rather upstre upstream in the batch plants.
ng Furthermore, there is great synergy in havi having multiple computer ant. computerss of the same sort in the same pl plant. Some of the major factors in thi thiss are:
Two elements of automatic control that have been or can be applied to all phases of the glass industry forming and finishing processes are the dedicated minicomputer for monitoring and control and variable frequency as a driving means of the process.
Information already available to a given computer, to enaLle it to do its control or monitoring the job, can easily and economically be passed on to other computers so these systems have on-line rapid access to data otherwise unavailable. otherwi se unavai lable. Data can be passed upstream, downstream or to a central management information computer allowing controlI of other parts of all owi ng the contro th thee process, and better management of the entire system.
The Dedicated Minicomputer Today, TOday, with reduced costs and complexity, minicomputers are not only economically justifiable in the batching and melting areas, but for cutting systems, spur line control, machine timing control, material flow control and downstream inspection and glass handling. Each of these not only can be but has been justified 0,1 011 its own merits in most of these areas. (Figure 1)
1
A duplication of computer hardware allows for reduced maintenance cost and for a great reduction in the investment in spares.
which determine thickness of the product, the liftout rolls, onto lehr rolls, past the inspection area to cutting and warehousing. From an automatic control standpoint, the critical thing here is that the roll zed so as not rollss be synchroni synchronized to mar the glass, and the steering rolls be controlled precisely enough so thickness of product can be relied upon. This must all be accomplished under extremely high temperature conditions, which means that all of the rolls no matter how finely finished will expand both laterally and thiss amount of growth wi will radially, and thi 11 be dependent upon the relative ambient to operating temperature change.
A similar duplication in interface hardware, that is the hardware that allows the computer to communicate both inputs and outputs to the entire system, also assures a significant reduction in maintenance and in spare parts costs. When all the equipment is supplied from a single systems house and proper thought is given to overall economics, additional economies in duplication of software and peripherals are also available.
The original drive system for a float glass line was a mechanical line shaft, with bull gears mounted on quick disconnect a taper on the individual rolls for a qUick means. As the line speeds became higher and exceeded 500 inches per minute, it became impractical to drive by this method, since too much whip in the line shaft at those speeds causes imperfect glass to be manufactured.
Variable Frequency Drives All of the major forming machines in the industry employ mechanical line shaft drives, or approximations di fferent reasons. reason s. of same of one form or another, for many different The invention of the reluctance synchronous motor in the late '50s made possible a reasonable and economical means of replacing the mechanical line shaft with an electrical system that duplicates, if not exceeds, the characteristics of the mechanical line shaft. This is extremely desirable, due to the fact that a mechanical line shaft is very definitely speed limited in performance, and also it is very desirable to sometimes modify line shaft performance to obtain special characteri stics such as draw or angular positioning capability.
The next step was to separate the line shaft into segments and/or to input power at multiple points. The solutions are many and varied. They range from analog drive systems with multiple gear units coupled to one another to form the line shaft, to highly sophisticated DC drive systems with digital regulation with a high degree of resolution that forces the individual rolls into synchron i zati on. Between these two extremes of performance fit the vari able frequency systems, whether they be rotati ng or static, which rely on the basic design of the reluctance synchroni zation without the synchronous motors to hold synchronization necessity of closing the loop.
As production rates increase, the variable frequency system offers the following advantages:
1. The input of power at many different points, I ine shaft whip. thereby eliminating backlash and Iine
The question then becomes, at how many points do you input power? Is it preferable to drive every roll with a 1/4 hp synchronous motor through a standard gear box, or is it better to drive multiples of three, four, five or six rolls with a larger synchronous motor and a grouping of precision chain or timing belts? Although use of chain or belts as a driving means may be disputed due to the possibi lity of backlash and/or stretching or growth due to wear, thi s method is exactly what is used on a "temporary" basis when something goes wrong on a float line today. Since a float line is unidirectional in operation, the problem of backlash is eliminated. Also, improvements in the basic design of these types of power transmitting devices, proven in other industries, should make them perfectly acceptable for continuous operation if properly designed into the system. (Figure 2)
2. The use of an AC motor for such power inwithitS inherent reliability and comparative freedom put with1tS from maintenance consideration.
3. Low cost, when compared to sophisticated digital DCsystems.
i:.... Inherent open
loop regulation.
The Flat Glass Industry The flat glass industry is perhaps the best example of how these two methods of automatic control have helped in conjunction with the float process, to make it one of the fastest growing industries in the world. In the U. S. alone, it has grown from a $1/2 billion per year U.S. industry in 1967 to more than a $3 billion industry today.
As the speeds of the float lines became greater and greater, the need for automation in either cutting, routing or packing and shipping increased significantly. The application of a dedicated minicomputer to one or more of these areas is economically justifiable, so the glass can be cut in various shapes automatically and then
Starting with the output of the forehearth, the glass is floated on a tin bath and guided by steering rolls,
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LOCA TIONS POSSIBLE MINIC OMPU TER LOCATIONS POSS IBLE MINICOMPUTER
FltlRE FIGlRE 11
FIGLru: FIGrnE22 33
directed to the proper packing, stacking or shipping conveyor. On cross-cutters, a small computer can positionpositi onregulate the heads with respect to the moving glass, and at the same time controls the turn-on of the cutter heads to produce cross cuts of glass of different desired widths simultaneously. Having gone that far, it is relatively straightforward to have a master computer organize a full day's production and schedule the slave computer to produce different widths of glass scheduled for different spur lines.
basically no elasticity whatsoever. The fibers can be pulled apart or compressed to a point, but it can be seen that any wide difference in speed between any two sections will cause the web to either pull apart and break, or compress such that a jam-up wi II 11 occur. Once again, variable frequency may be employed. The basic requirement is for synchronization synchroni zation of one section with another. The variable frequency system has the providing advantage of providi ng thi s synchroni zation open-loop, and makes use of a relatively inexpensive motor (when compared to the DC motor) which requires little or no mai ntenance.
The flexibility flexibi I ity of an on-line on-I ine computer with a keyboard C RT arrangement allows the operator to interface CRT closely with the process, to make changes as desired to suit immediate production requirements, and to keep exact track of where production stands at any given time.
If draw should be required between some sections sections,I this can be accomplished through an electrical differential or mechanical differential that would drive the section where positive or negative draw is required, slightly faster or slower than the referenced section.
The cordwood or longitudinal cutters are equally thi s computer, and suitable to be position controlled by this once again thi s device can work in conjunction with the optimize master to optimi ze production and to keep production at a rate suitable to each of several spur lines. (Figure 3)
In the computer area, the manufacturing of glass fibers was one of the first industries where computer control using the large computer was explored in the melting exi st on-line, on-I i ne, area. Since these large computers already exist many manufacturers are extending their use to lapper controll trol, forming section control, binder flow and various trim saws and choppers. However, thi s is being done because the Iarge large computer exi exists, sts, and its core memory should be exploited to the fullest.
Finally, due to the increasing line speeds, automatic inspection and quality control should be mentioned. The human eye is being replaced by many combinations of lasers, gages both contact and non-contact, and other devices. The outputs of these devices could be fed to the minicomputer, so they would sort the marginal or bad sections of the ribbon and relegate same to some downstream section for additional operations or to the cullet chute.
The minicomputer applied to these areas would be far more economically justifi ab le today, si nce these control areas have little to do with the melting process. Programming would be simplified, and the switch to manual operation would be much more easi Iy accompl i shed than when a Ilarge arge computer goes off line.
The Glass Fiber Industry Although finished glass fibers take many forms, etc. I by far the including textile, glass mats, wool, etc., largest proportion of the material is produced as wool for insulation. The typical glass wool line consists of a forming section, ramp section, oven section, backing si itting section and roll-up or section, conveyor section, slitting cutting area. This is very basically a system of conveyors that collects the fibers, forms a mat of desired thickness and extracts the moisture within, cures the product, provides a backing for it and then slits it or cuts it into usable sections to be used as insulation. (Figure 4)
Di Discrete screte P Parts arts Manufacturing This segment of the glass industry is where the greatest advances can be made immediately in automatic control of forming and finishing, since it is still largely a start/stop operation and does not lend itself to continuous motion as readily as the manufacture of flat glass or glass fibers. Continuous motion does exist in the manufacture of light bulbs, which are manufactured on ribbon machines machines,, and this type of process has been tried out in the container industry with mixed results. The Heye machine, manufactured in Germany, makes certain claims alluding to success with the continuous motion process in contai ner man ufacture ufacture,I but regard Iess I ess of the magni tude of these successes, this type of machine is in the prototype stage.
The typical drive system here again tries to apshaft,, but since the length of the conproximate the line shaft veyor sections and amount of work performed on same rehorsepower,I the total horsepower require considerable horsepower quirement of the complete wool line makes a line shaft very impractical. Therefore, what has been used in the past is the sectional DC drive with analog regulation. As the speeds of the process have increased, many manufacturers have gone to digital regulation of the individual sections, and there is the possible requirement for negative draw upstream from the oven section and positive down stream of the oven. draw downstream
In this area, we must look at the existing type machines which have been used in the day-to-day manufacture of bottles and tumblers. Machines such as the I-S machine, the Hartford 28, and the Lynch press, to name a few, are in use throughout the industry. These mechanical marvels have been redesigned mechanically
Close study of the product shows that it has
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(Figure 7) shows how a minicomputer could be applied to an existing I-S machine to eliminate the mechanical timing drum. A common line shaft is still shown in this example, with a shaft encoder providing feedback to the computer. It would be possible to eliminate the Iine line shaft entirely and place the shaft encoder on the feeder or gob distributor to electronically establish the timing on the entire machine.
over the past decade, but electrically they are still in their infancy. Again, there has been the need for the elimination of the mechanical line shaft and the manual transfer of ware to some type of meaningful electrical drive system. Again, it is proper to look at variable frequency, not only for its inherent synchronization capabilities, but also for the ease that angular positioning can be accomplished by use of mechanical or electrical differentials in the system.
The proper application of the minicomputer would provide sufficient feedback from malfunctions in the formi ng process, to prevent the filling fi 11 ing of the tempering temperi ng Ilehr ehr ing with reject ware that will ultimately be rejected in the inspection area and relegated to the cullet chute. Proper sensors to accomplish this are in partial existence today, but many more inspection devices for the hot end of the line must be perfected. Already we have control lasers and other non-contact devi ces that can be used at the hot end to inspect and reject ware before it enters the tempering lehr. When these devices are interfaced to provide feedback to the dedicated minicomputer, production rates could be significantly improved by spotting malfunctions from the forming machinery at a much earlier time, resulting in correction of the fault before too many rejects pile up. Machine efficiency would be significantly improved and quality control problems at the cold end would be eased as well.
As the industry goes to higher and higher production rates, it becomes much more important to get a smooth flow of the discrete parts down the line. Although a newly installed machine has a minimum of mechanical backlash, the continuous running of this machine will, in time, cause improper operation due to the innumerable pulleys, chains, transmissions, gear boxes, etc., that make up the mechanical line shaft system. The industry should be looking at systems to individually drive the various sections at as many points as possible. On the I-S machine this will mean individual distributor, stributor, timing drum shaft, drives on the feeder, gob di takeout conveyor, star wheel transfer, lehr loader, stacker, and in some cases the annealling lehr. (Figure 5) In tumbler manufacturing the individual drives would go on the feeder, blowing machine or press, takeout conveyor, burn-off machine or glazer, takeout stub conveyor and again the lehr loader. (Figure 6)
The minicomputer would also offer the following benefits:
1. Improved operator safety, in that section adjustment would be accomplished by the setting of a potentiometer instead of adjustment to the timing drum by an operator with a wrench.
Whether these individual drive units get their source of power from rotating or static variable frequency is immaterial, but what does matter is that employment of these type units will go a long way in not only producing ware at a faster rate without loss, but will result in accomplishment of job changes in much shorter periods of time. It has been reported that loss of ware % after the forming operation can run as high as from 3 3/'0 to 5/'0. This can occur from jam-ups, articles falling over in the transfer from the takeout conveyor to the lehr loader, lehr loader to the lehr, and improper operation of the stacker. Individually driven sections have proved the elimination of most of these types of losses. Also, when jam-ups do occur, it is far easier to reset an overload than to replace a shear pin or a dry transmission or gear box.
2. Job changes would be significantly easier, due to the"use of a taped program as opposed to resetting cally. all of the devi ces mechani devices mechanically. 3. The adjustments themselves would be more accurate;particularly on high-speed jobs, due to a keyboard input. 4. The possibility of automatic mold swabbing due to finer resolution of settings on the timing drums. G.C.M.I. reports control to one degree of arc -- compared to drum-operated equipment, whose positive control is limited to five degrees.
Once the individual drive points have been accomplished, it is proper to look at the possibilities of the application of the dedicated minicomputer to the process. The mechanical timing drum has been replaced experimentally by the electronic timing drum, where the opening and closing of the air-actuated valves had been accompl i shed by solenoids actuated by static logic. The application of the minicomputer in this area allows for its use not only to replace the mechanical timing drum but also to better control the inspection and quality control area of the ware as it goes through the various inspection points at the cold end.
This last point is probably the most significant of all, since 0 SHA is extremely concerned about the I. S. machine and its operation. The noise level of the cooling air was the first area to come under OSHA's scrutiny, since it was obvious that something could be done immediately to alleviate that condition. It is only a matter of time before mold swabbing and manual timing drum adjustment come under attack from the operator safety standpoint.
6
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CONCLUSION
Holscher, H. H. "The Glass Primer" Copyright 1972 - Magazines for Industry
Most segments of the glass industry today find themselves in a production-limited condition. This condition could be alleviated in part by the proper application of electrical devices that exi st but have been randomlyapplied. The proper application of the devices discussed in this paper would have the following real and immediate benefits:
Jakes, Jerry, "Better Motors Drive Glass Machinery" Glass Industry Magazine, Vol. 53 (July 1972) No. 7 Luke, H. D., "Automation for Productivity" Copyright 1972 - Wiley-Becker & Hayes Walker, R. C., "Solid State Inverters for Electrical Speed and Position Synchronization for Container Machinery from Feeder to the Lehr", IEEE Conference Record of 6th Annual Meeting IGA (1971) (1971> 675-685
1. Higher line speeds due to elimination of problems associ ated with mechanical mechan ical Iine line shafts. associated 2. Greater flexibility in machine layout, and solution of"'iJroblems ofProblems such as draw, and precise adjustable position control, etc. 3. Application of established, reliable electrical devices, drive and computer, that will yield simplified better control schemes as well as the ability to coIcollect data for product and manufacturing process analysi analysis. Iect s. 4. Elimination or reduction of operator control for increased and reliable quality control to advance from the art stage to the scientific analysis stage which would re sult in tighter control of the process by management. result It is a well-known fact that glass has a very low raw material cast. Also, that it is converted from raw material to salable products in a single operation. Therefore, glass is better suited to automation than any other basi c industry. Technological advances in drive and control equipment have proven reliable enough to be used in a "Glass " Glass House" atmosphere, if properly applied. They stand ready to be used as a tool in the industry's critical need to improve producti productivity. vity.
REFERENCES AND BIBLIOGRAPHY Ashton, R. L. "High Speed Non-Contact Dimensional Gaging of Glass Containers", Containers ", IIEEE EEE Conference Record <1971> 669-674 of 6th Annual Meeting;IGA (1971) Camino, N.A., "Computer Directed Systems for Cutting and Handling", IEEE Conference Record of 7th Annual Meeting; IGA (1972) 607-614 "The Continuous Motion Concept", Glass Industry Magazine, Vol. 52 (July 1971), 1971>, No. 7 Fisher, P.H. "Inverters for Position Control", Owens-Illinois, paper delivered at Design Engineering 20, 1971, New York, New York Conference, April 20,1971, Glass Containers Manufacturing Institute Glass Containers - 1972 Edition
9
Gerald A. Jakes Reliance Electric Company Toledo, Ohio
Although the industry began applying large comex puters to the process before minicomputers were in existence, there are many reasons for applying the dedicated minicomputer even if a large process computer already exists in the plant.
ABSTRACT Great improvements have taken place in the manufacturing of glass in the last decade. These improvements have been largely mechanical in nature, having to do with upgrading of forming and finishing machinery to maximize production rates per present-day standards. Now is the time to concentrate on the application of electrical equipment to these new and redesigned machines.
centr al If an entire process line is run by a large central will computer, a malfunction in any section wi 1I cause the entire proces processs to go down. If one of a number of minicomputers fails, that portion of the process can be run in manual unti I the fault is corrected. The cost of the dedicated minicomputer is about equal to the required portion of the time shared computer.
The forming and finishing area of any glass plant is and should be coming under increased scrutiny by company management.
The programming minicomputer is simpler, Simpler, not conc ern hims elf with concern himself llarge arge process computer.
It is this area where most of the labor in a typical glass plant is found. Since glass has the lowest raw material cost of any basic material, any decrease in the labor content per fini shed piece makes the product increasingly salable in its traditional markets and opens up new markets based on continuing research and advancing technology.
and / or software package of a and/or because the programmer need other programs exi sting in the existing
The large computer can become the supervisory computer to one or more dedicated minicomputers. As such, it can command comman d the dedicated computers to perform predetermined major function s, as well as gather gath er data to functions, produce logs log s rel ated to production, inventory, downtime related and efficiency of the process.
Automatic control has been applied in the industry, but sporadically and generally not in the area of forming and finishing; am in the melting area and finishingj but rather upstre upstream in the batch plants.
ng Furthermore, there is great synergy in havi having multiple computer ant. computerss of the same sort in the same pl plant. Some of the major factors in thi thiss are:
Two elements of automatic control that have been or can be applied to all phases of the glass industry forming and finishing processes are the dedicated minicomputer for monitoring and control and variable frequency as a driving means of the process.
Information already available to a given computer, to enaLle it to do its control or monitoring the job, can easily and economically be passed on to other computers so these systems have on-line rapid access to data otherwise unavailable. otherwi se unavai lable. Data can be passed upstream, downstream or to a central management information computer allowing controlI of other parts of all owi ng the contro th thee process, and better management of the entire system.
The Dedicated Minicomputer Today, TOday, with reduced costs and complexity, minicomputers are not only economically justifiable in the batching and melting areas, but for cutting systems, spur line control, machine timing control, material flow control and downstream inspection and glass handling. Each of these not only can be but has been justified 0,1 011 its own merits in most of these areas. (Figure 1)
1
A duplication of computer hardware allows for reduced maintenance cost and for a great reduction in the investment in spares.
which determine thickness of the product, the liftout rolls, onto lehr rolls, past the inspection area to cutting and warehousing. From an automatic control standpoint, the critical thing here is that the roll zed so as not rollss be synchroni synchronized to mar the glass, and the steering rolls be controlled precisely enough so thickness of product can be relied upon. This must all be accomplished under extremely high temperature conditions, which means that all of the rolls no matter how finely finished will expand both laterally and thiss amount of growth wi will radially, and thi 11 be dependent upon the relative ambient to operating temperature change.
A similar duplication in interface hardware, that is the hardware that allows the computer to communicate both inputs and outputs to the entire system, also assures a significant reduction in maintenance and in spare parts costs. When all the equipment is supplied from a single systems house and proper thought is given to overall economics, additional economies in duplication of software and peripherals are also available.
The original drive system for a float glass line was a mechanical line shaft, with bull gears mounted on quick disconnect a taper on the individual rolls for a qUick means. As the line speeds became higher and exceeded 500 inches per minute, it became impractical to drive by this method, since too much whip in the line shaft at those speeds causes imperfect glass to be manufactured.
Variable Frequency Drives All of the major forming machines in the industry employ mechanical line shaft drives, or approximations di fferent reasons. reason s. of same of one form or another, for many different The invention of the reluctance synchronous motor in the late '50s made possible a reasonable and economical means of replacing the mechanical line shaft with an electrical system that duplicates, if not exceeds, the characteristics of the mechanical line shaft. This is extremely desirable, due to the fact that a mechanical line shaft is very definitely speed limited in performance, and also it is very desirable to sometimes modify line shaft performance to obtain special characteri stics such as draw or angular positioning capability.
The next step was to separate the line shaft into segments and/or to input power at multiple points. The solutions are many and varied. They range from analog drive systems with multiple gear units coupled to one another to form the line shaft, to highly sophisticated DC drive systems with digital regulation with a high degree of resolution that forces the individual rolls into synchron i zati on. Between these two extremes of performance fit the vari able frequency systems, whether they be rotati ng or static, which rely on the basic design of the reluctance synchroni zation without the synchronous motors to hold synchronization necessity of closing the loop.
As production rates increase, the variable frequency system offers the following advantages:
1. The input of power at many different points, I ine shaft whip. thereby eliminating backlash and Iine
The question then becomes, at how many points do you input power? Is it preferable to drive every roll with a 1/4 hp synchronous motor through a standard gear box, or is it better to drive multiples of three, four, five or six rolls with a larger synchronous motor and a grouping of precision chain or timing belts? Although use of chain or belts as a driving means may be disputed due to the possibi lity of backlash and/or stretching or growth due to wear, thi s method is exactly what is used on a "temporary" basis when something goes wrong on a float line today. Since a float line is unidirectional in operation, the problem of backlash is eliminated. Also, improvements in the basic design of these types of power transmitting devices, proven in other industries, should make them perfectly acceptable for continuous operation if properly designed into the system. (Figure 2)
2. The use of an AC motor for such power inwithitS inherent reliability and comparative freedom put with1tS from maintenance consideration.
3. Low cost, when compared to sophisticated digital DCsystems.
i:.... Inherent open
loop regulation.
The Flat Glass Industry The flat glass industry is perhaps the best example of how these two methods of automatic control have helped in conjunction with the float process, to make it one of the fastest growing industries in the world. In the U. S. alone, it has grown from a $1/2 billion per year U.S. industry in 1967 to more than a $3 billion industry today.
As the speeds of the float lines became greater and greater, the need for automation in either cutting, routing or packing and shipping increased significantly. The application of a dedicated minicomputer to one or more of these areas is economically justifiable, so the glass can be cut in various shapes automatically and then
Starting with the output of the forehearth, the glass is floated on a tin bath and guided by steering rolls,
2
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Dc) DQ
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liII
FURNACE ACE FURN
FORMING
COTD ••
END--
LOCA TIONS POSSIBLE MINIC OMPU TER LOCATIONS POSS IBLE MINICOMPUTER
FltlRE FIGlRE 11
FIGLru: FIGrnE22 33
directed to the proper packing, stacking or shipping conveyor. On cross-cutters, a small computer can positionpositi onregulate the heads with respect to the moving glass, and at the same time controls the turn-on of the cutter heads to produce cross cuts of glass of different desired widths simultaneously. Having gone that far, it is relatively straightforward to have a master computer organize a full day's production and schedule the slave computer to produce different widths of glass scheduled for different spur lines.
basically no elasticity whatsoever. The fibers can be pulled apart or compressed to a point, but it can be seen that any wide difference in speed between any two sections will cause the web to either pull apart and break, or compress such that a jam-up wi II 11 occur. Once again, variable frequency may be employed. The basic requirement is for synchronization synchroni zation of one section with another. The variable frequency system has the providing advantage of providi ng thi s synchroni zation open-loop, and makes use of a relatively inexpensive motor (when compared to the DC motor) which requires little or no mai ntenance.
The flexibility flexibi I ity of an on-line on-I ine computer with a keyboard C RT arrangement allows the operator to interface CRT closely with the process, to make changes as desired to suit immediate production requirements, and to keep exact track of where production stands at any given time.
If draw should be required between some sections sections,I this can be accomplished through an electrical differential or mechanical differential that would drive the section where positive or negative draw is required, slightly faster or slower than the referenced section.
The cordwood or longitudinal cutters are equally thi s computer, and suitable to be position controlled by this once again thi s device can work in conjunction with the optimize master to optimi ze production and to keep production at a rate suitable to each of several spur lines. (Figure 3)
In the computer area, the manufacturing of glass fibers was one of the first industries where computer control using the large computer was explored in the melting exi st on-line, on-I i ne, area. Since these large computers already exist many manufacturers are extending their use to lapper controll trol, forming section control, binder flow and various trim saws and choppers. However, thi s is being done because the Iarge large computer exi exists, sts, and its core memory should be exploited to the fullest.
Finally, due to the increasing line speeds, automatic inspection and quality control should be mentioned. The human eye is being replaced by many combinations of lasers, gages both contact and non-contact, and other devices. The outputs of these devices could be fed to the minicomputer, so they would sort the marginal or bad sections of the ribbon and relegate same to some downstream section for additional operations or to the cullet chute.
The minicomputer applied to these areas would be far more economically justifi ab le today, si nce these control areas have little to do with the melting process. Programming would be simplified, and the switch to manual operation would be much more easi Iy accompl i shed than when a Ilarge arge computer goes off line.
The Glass Fiber Industry Although finished glass fibers take many forms, etc. I by far the including textile, glass mats, wool, etc., largest proportion of the material is produced as wool for insulation. The typical glass wool line consists of a forming section, ramp section, oven section, backing si itting section and roll-up or section, conveyor section, slitting cutting area. This is very basically a system of conveyors that collects the fibers, forms a mat of desired thickness and extracts the moisture within, cures the product, provides a backing for it and then slits it or cuts it into usable sections to be used as insulation. (Figure 4)
Di Discrete screte P Parts arts Manufacturing This segment of the glass industry is where the greatest advances can be made immediately in automatic control of forming and finishing, since it is still largely a start/stop operation and does not lend itself to continuous motion as readily as the manufacture of flat glass or glass fibers. Continuous motion does exist in the manufacture of light bulbs, which are manufactured on ribbon machines machines,, and this type of process has been tried out in the container industry with mixed results. The Heye machine, manufactured in Germany, makes certain claims alluding to success with the continuous motion process in contai ner man ufacture ufacture,I but regard Iess I ess of the magni tude of these successes, this type of machine is in the prototype stage.
The typical drive system here again tries to apshaft,, but since the length of the conproximate the line shaft veyor sections and amount of work performed on same rehorsepower,I the total horsepower require considerable horsepower quirement of the complete wool line makes a line shaft very impractical. Therefore, what has been used in the past is the sectional DC drive with analog regulation. As the speeds of the process have increased, many manufacturers have gone to digital regulation of the individual sections, and there is the possible requirement for negative draw upstream from the oven section and positive down stream of the oven. draw downstream
In this area, we must look at the existing type machines which have been used in the day-to-day manufacture of bottles and tumblers. Machines such as the I-S machine, the Hartford 28, and the Lynch press, to name a few, are in use throughout the industry. These mechanical marvels have been redesigned mechanically
Close study of the product shows that it has
4
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FIGJRE 3 FIGURE
5
(Figure 7) shows how a minicomputer could be applied to an existing I-S machine to eliminate the mechanical timing drum. A common line shaft is still shown in this example, with a shaft encoder providing feedback to the computer. It would be possible to eliminate the Iine line shaft entirely and place the shaft encoder on the feeder or gob distributor to electronically establish the timing on the entire machine.
over the past decade, but electrically they are still in their infancy. Again, there has been the need for the elimination of the mechanical line shaft and the manual transfer of ware to some type of meaningful electrical drive system. Again, it is proper to look at variable frequency, not only for its inherent synchronization capabilities, but also for the ease that angular positioning can be accomplished by use of mechanical or electrical differentials in the system.
The proper application of the minicomputer would provide sufficient feedback from malfunctions in the formi ng process, to prevent the filling fi 11 ing of the tempering temperi ng Ilehr ehr ing with reject ware that will ultimately be rejected in the inspection area and relegated to the cullet chute. Proper sensors to accomplish this are in partial existence today, but many more inspection devices for the hot end of the line must be perfected. Already we have control lasers and other non-contact devi ces that can be used at the hot end to inspect and reject ware before it enters the tempering lehr. When these devices are interfaced to provide feedback to the dedicated minicomputer, production rates could be significantly improved by spotting malfunctions from the forming machinery at a much earlier time, resulting in correction of the fault before too many rejects pile up. Machine efficiency would be significantly improved and quality control problems at the cold end would be eased as well.
As the industry goes to higher and higher production rates, it becomes much more important to get a smooth flow of the discrete parts down the line. Although a newly installed machine has a minimum of mechanical backlash, the continuous running of this machine will, in time, cause improper operation due to the innumerable pulleys, chains, transmissions, gear boxes, etc., that make up the mechanical line shaft system. The industry should be looking at systems to individually drive the various sections at as many points as possible. On the I-S machine this will mean individual distributor, stributor, timing drum shaft, drives on the feeder, gob di takeout conveyor, star wheel transfer, lehr loader, stacker, and in some cases the annealling lehr. (Figure 5) In tumbler manufacturing the individual drives would go on the feeder, blowing machine or press, takeout conveyor, burn-off machine or glazer, takeout stub conveyor and again the lehr loader. (Figure 6)
The minicomputer would also offer the following benefits:
1. Improved operator safety, in that section adjustment would be accomplished by the setting of a potentiometer instead of adjustment to the timing drum by an operator with a wrench.
Whether these individual drive units get their source of power from rotating or static variable frequency is immaterial, but what does matter is that employment of these type units will go a long way in not only producing ware at a faster rate without loss, but will result in accomplishment of job changes in much shorter periods of time. It has been reported that loss of ware % after the forming operation can run as high as from 3 3/'0 to 5/'0. This can occur from jam-ups, articles falling over in the transfer from the takeout conveyor to the lehr loader, lehr loader to the lehr, and improper operation of the stacker. Individually driven sections have proved the elimination of most of these types of losses. Also, when jam-ups do occur, it is far easier to reset an overload than to replace a shear pin or a dry transmission or gear box.
2. Job changes would be significantly easier, due to the"use of a taped program as opposed to resetting cally. all of the devi ces mechani devices mechanically. 3. The adjustments themselves would be more accurate;particularly on high-speed jobs, due to a keyboard input. 4. The possibility of automatic mold swabbing due to finer resolution of settings on the timing drums. G.C.M.I. reports control to one degree of arc -- compared to drum-operated equipment, whose positive control is limited to five degrees.
Once the individual drive points have been accomplished, it is proper to look at the possibilities of the application of the dedicated minicomputer to the process. The mechanical timing drum has been replaced experimentally by the electronic timing drum, where the opening and closing of the air-actuated valves had been accompl i shed by solenoids actuated by static logic. The application of the minicomputer in this area allows for its use not only to replace the mechanical timing drum but also to better control the inspection and quality control area of the ware as it goes through the various inspection points at the cold end.
This last point is probably the most significant of all, since 0 SHA is extremely concerned about the I. S. machine and its operation. The noise level of the cooling air was the first area to come under OSHA's scrutiny, since it was obvious that something could be done immediately to alleviate that condition. It is only a matter of time before mold swabbing and manual timing drum adjustment come under attack from the operator safety standpoint.
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FIIllRE l!
RAW MATERIAL.S MATERIA",S
MELTING TANK
BINDER SPRAY
FORMING
'HOER 'UOER
COOLING ~ SLITTING
APPLICATOR
001 GO. OISTIIIIIIUTOIt DISTRIBUTOR
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CONVEYOR COHV[YO"
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I. IlI[C""''''(A.. "[CMANICAI.. WITH W'TH u.rCTJltle [L.ECTJUC ,to.On: "'''OT! CDNTJlU)t,.. CONUOl 2. !lrCTlUC
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z. Z.
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DC DRIVEN ALTENATOR
*
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FIGLRE 5 1 7
l.EHR
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~QAKE
OUT CONVEYOR MOTOR
MOTOR
o FEEDER
o
FIGURE 6
MOTOR
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LEHR LOADER MOTOR
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EXIT POSITION
COMMON LINE SHAFT TO ALL SECTIONS SHAFT ENCODER
0359· 0 - 359'
-
-
-
I
-OPERATOR CONTROL
30 OUTPUTS PER SECTION
I I
I I
I I I
I
4·CD·13
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FIGlRE 7
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RECORDER
8
23·8 OUTPUT CD 12 115 VAC
CONCLUSION
Holscher, H. H. "The Glass Primer" Copyright 1972 - Magazines for Industry
Most segments of the glass industry today find themselves in a production-limited condition. This condition could be alleviated in part by the proper application of electrical devices that exi st but have been randomlyapplied. The proper application of the devices discussed in this paper would have the following real and immediate benefits:
Jakes, Jerry, "Better Motors Drive Glass Machinery" Glass Industry Magazine, Vol. 53 (July 1972) No. 7 Luke, H. D., "Automation for Productivity" Copyright 1972 - Wiley-Becker & Hayes Walker, R. C., "Solid State Inverters for Electrical Speed and Position Synchronization for Container Machinery from Feeder to the Lehr", IEEE Conference Record of 6th Annual Meeting IGA (1971) (1971> 675-685
1. Higher line speeds due to elimination of problems associ ated with mechanical mechan ical Iine line shafts. associated 2. Greater flexibility in machine layout, and solution of"'iJroblems ofProblems such as draw, and precise adjustable position control, etc. 3. Application of established, reliable electrical devices, drive and computer, that will yield simplified better control schemes as well as the ability to coIcollect data for product and manufacturing process analysi analysis. Iect s. 4. Elimination or reduction of operator control for increased and reliable quality control to advance from the art stage to the scientific analysis stage which would re sult in tighter control of the process by management. result It is a well-known fact that glass has a very low raw material cast. Also, that it is converted from raw material to salable products in a single operation. Therefore, glass is better suited to automation than any other basi c industry. Technological advances in drive and control equipment have proven reliable enough to be used in a "Glass " Glass House" atmosphere, if properly applied. They stand ready to be used as a tool in the industry's critical need to improve producti productivity. vity.
REFERENCES AND BIBLIOGRAPHY Ashton, R. L. "High Speed Non-Contact Dimensional Gaging of Glass Containers", Containers ", IIEEE EEE Conference Record <1971> 669-674 of 6th Annual Meeting;IGA (1971) Camino, N.A., "Computer Directed Systems for Cutting and Handling", IEEE Conference Record of 7th Annual Meeting; IGA (1972) 607-614 "The Continuous Motion Concept", Glass Industry Magazine, Vol. 52 (July 1971), 1971>, No. 7 Fisher, P.H. "Inverters for Position Control", Owens-Illinois, paper delivered at Design Engineering 20, 1971, New York, New York Conference, April 20,1971, Glass Containers Manufacturing Institute Glass Containers - 1972 Edition
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