Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COrlPUTE~ CONTROL FOR GLASSWARE FORMING MACHINE
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BACKGROUND OF THE INVENTION
This invention relates generally to control systems
for glassware forming machines, and deals more particularly
with a system which incorporates a general purpose digiial
computer for storing a sequence of events within a machine
cycle, and the system is capable of controlling the operation
of the machine without the necessity of generating, during each
feeder cycle, multiple pulses from the glass feeder which pro-
vides gobs to the machine, or from a drive shaft such as thatassociated with the take away conveyor which carries the glass-
ware articles away from the machine.
Prior art approaches to the electronic control of
glassware forming machines are exemplified by U~ S. ~atents
No. 3,762,907; No. 3,877,915; No. 3,905,793; and No. 3,969,703
and U. K. PJatent No. 1,441,099. In all of these prior art
patents the basic premise has been to assume that one must
have timing means responsive to a drive shaft or the like to
provide an instantaneous indication of the elapsed time in
each cycle of operation of the machine. In U. S. Patent No.
3,762,907; No. 3,377,915 and No. 3,969,703 and in U. K.
Patent No. 1,441,099 a pulse generator provides 360 or more
pulses per machine cycle, and is driven by a drive shaft
associated with the molten glass feeder, or the take away con-
veyor, so that the "timing means" for the glassware machine is
continually related to the speed of rotation of a rotating machine
member. In U. S. Patent No. 3,905,793 no pulse generator is
u~ed, but means is provided for generating a binary coded
decimal signal indicative of the instantaneous position of a
shaft, and the said signal is compared, sequentially, to a
programmed sequence of events stored in memory for producing ~-
the necessary output signals to control the machine events. ;
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All ~f these prior art systems require that a shaft,
or other rotating member, be closely monitored during the
machine cycle, and that a real time comparison be made to
provide the output signals for the various events (usually an
"on" or "off" signal to solenoid valves) in the typical
Hartford I. S. type glassware ~orming machine.
In a typical Hartford I. S. type of glassware forming
machine, molten glass gobs are delivexed from a ~eeder, by
means of a gob distribution system, in a predetermined
sequence to the upwardly open blank molds of the various
machine sections. Each section comprises a self-contained
unit which includes a blank mold station and a blow mold station.
The gob of molten glass is formed into a parison at the blank
station, and then transferred to the blow station by a neck
ring arm which includes a neck mold. The neck mold not only
mates with the blank mold at the blank station but also serves
to support the parison during transfer to the blow station.
The blank mold may be of the split or the solid type
and is adapted to mate with the neck mold. The neck mold is of
the split type, and is annular in shape with a central opening
to receive a vertically reciprocable plunger which presses the
gob into the blank mold in the "press and blow" process, or
which plunger is associated with a thimble to permit the
parison to be formed by the "blow and blow" process. This
latter process provides for "counter blow" air at the blank
station in addition to the "final blow" air at the blow station.
~he description to ~ollow is not limited to either process.
The glass gobs are formed at a rate dictated by the ~-
size and shape of ~he ware to be produced, and these gobs
are ~ed through a distribution system to the various blank mold
cavities. Each blank cavity is upwardly open, and a ~unnel is
usually provided to move in onto the closed blank mold for
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guiding the gob into such cavity. The gob drops through the
funnel into the cavity, and into the neck mold, which is
always closed except for a shor~ time at the blow station for
release of the parison. In this "delivery mode" of the machine
the plunger and the thimble must be raised to define the neck
opening of the ware. This initial mode is triggered either
upon "start up" of the machine, or of a master section thereof,
or in accordance with the gob distributor system.
The next mode of operation of the machine can be
characterized as one of "settling" the gob or charge into the
neck mold. This is accomplished in the usual "blow and blow"
process by bringing a baffle down onto the funnel, and pro-
viding air to the baffle for "settling" the charge in the blank
; mold. If no funnel is used in loading the gob, the baffle may
move directly in on top of the blank mold. As so configured
the blank station of the machine section is in its "parison
settle" mode. After settle blowing has been completed the
i baffle, and funnel, are returned to their inactive positions,
respectively.
The next mode of operation of the machine occupies
only a short time, and can be characterized as "parison corkage
reheat." The plunger moves downwardly away from the neck of
1 the parison alLowing the heat of the glass to stabilize in
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this part of the parison. This short pause softens the glass
surface by internal conduction, at least in the area where the
plunger tip has caused it to cool during the "delivery" and
"settle" modes, and as so configured ~he machine is in its
"corkage reheat" mode
The next mode of operation of the machine can be
characteriæed as one of "parison forming," and in the "blow
and blow" process such forming is carried out by introducing
counter blow air to the softened area of the parison. The -
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mechanical machine configuration is only altered from the
previous mode in that the baffle is lowered onto the blank
mold. This mode will see the gob expanded to fill the upper
regions of the blank cavity defined by the blank mold and by
the baffle. After allowing time for this preliminary forming
the counter blow air is turned oEf, the baffle is returned to
its inactive position, and the split blank mold is ready for
opening. As so configured the blank station of the machine is
in its "parison forming" or "counter blow" mode.
The next mode involves "reheating" parison and the
initial phase is accomplished simply by opening the split
blank mold. With the blank mold open the parison is not in
contact with any mold parts except the neck mold. This con-
figuration allows the heat stored in the thick walled parison
to raise the temperature of its external surfaces, hence the
derivation of the term "reheat" mode. This phase can be
called "blank side reheat."
Once the blank mold has completely opened, the neck
ring arm inverts the neck mold and the parison along with it.
This phase of the reheat mode can be characterized, thermo-
dynamically, as "invert reheat." This reheating continues at
least until the parison has been transferred to the blow
station. As the parison reaches the blow station the third
phase of reheat occurs. The blow mold closes around the
parison and around a bottom plate, which will be spaced below -
that end of the parison opposite it~ neck or open end. The ;
blow mold has an upper portion which supports the parison from
just below its finish, allowing the neck mold to be opened
prior to revert, or return movement of the neck ring mold. The
neck ring mold recloses during return movement so that the blank
mold can close around it once the neck mold has returned to the
blank station.
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The next mode involves final forming of the body of
the ware, the finish of the ware having been formed by the neck
mold at the blank station and during transfer. The final blow
air is delivered to the interior of the parison by a blow head
which moves down onto the ~op of the closed blow mold. After a
preset time for final blowing the air is turned off and the blow
head returned to its inactive position. The blow mold opens and
take-out tongs (open) are swung into the blow station. The
tongs close around the newly formed ware and the article is
lifted off the bottom plate for delivery to the deadplate por-
tion of a take-away conveyor system.
The above described cycle of oepration is represent-
ative of the typical I. S. machine, and the various events can
be seen to comprise simply the turning on or off certain valves
in each machine section. This is achieved by the control of
solenoids through the control system to be described. The
concept of dividing up the cycle into various modes is described
in the prior art U. S. Patents No. 3,877,915 and No. 3,905,793.
However, these prior art patents, and the others referred to
above, do not provide for programming the time period of the
machine cycle itself. Insofar as changes to the speed of the
~eeder, or take away conveyor drive shaft are encountered in
these prior art systems, changes to the frequency of a pulse
generator tied thereto will necessarily be encountered.
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The object of the present invention is to provide a ~
control system for a glassware forming machine, which not only ~ ; -
includes a general purpose digital computer with suitable --
memory, and access thereto for producing control signals to
solenoid valves or the like when appropriate, but which system -
also stores a sequence of events within a machine cycle, and
the system is capable of controlling the operation of the machine
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without the necessity of generating, during each feeder cycle,
multiple pulses from the glass feeder which provides gobs to
the machine, or from a drive shaft such as that associated
with the take away conveyor which carries the gla~sware
articles away from the machine.
The chief aim of the present invention is to provide
a control system for a glassware forming machine which system
not only utilizes a commercially available minicomputer for
taXing advantage of its memory and its programming capability,
lQ but which system also avoids the necessity for a shaft encoder
or pulse generator to time the interrupts required to achieve
the inherent sequential control basic to the I. S. type, and
other types, of glassware forming machines.
In keeping with this aim of the present invention, a
simple sensox, or proximity switch, is provided on the feeder
to update the programmed sequence of events once per cycle. The
interrupts required to sequence the solenoids in accordance with
the stored program are derived from a commercially available
function generator tied directly to the processor of the mini-
computer.
In accordance with a preferred embodiment of theinvention there is provided, a glassware forming machine having
at least one section, which section includes a set of components
controlled by an associated set of two state (onJoff) devices
` switchable between their on and off states in accordance with a
cyclically repeated sequential program of switching events, and
an associated feeder with a cyclically movable part which feeder
provides a gob of glass to said one section during each cycle of
said feeder part, characteri~ed by: means for producing a ref-
erence pulse once per cycle of said feeder part which reference
~; pulse determines and occurs at a given angle of the machine
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cycle, means responsive solely to said feeder pulses for
providing a substantially continuous instantaneous representation
of the cycle angle of said machine throughout each cycle there-
of, and means responsive to said substantially continuous in-
stantaneous representation of the machine c~cle angle for turn-
ing on and off said set of two state devices in accordance with
said sequential program of switching events.
In accordance with a :Eurther embodiment of the :
invention there is provided, a glassware forming machine
having at least one section, which section includes a set of com~
ponents controlled by an associated set of two-state (on/off) : .
devices switchable between their on and off states in accordance .
with a cyclically repeated sequential program of switching : :
events to cause said set of components to form a gob of glass
into an article during each repeat of said program, a memory
means storing a plurality of elements defining a sequential pro- ... .
gram of such qwitching events, each of said elements including
a cycle angle word indicating the cycle angle at which an event
defined by the element is to occur, and a feeder with a cyclic-
ally movable part which feeder provides a gob of glass to said
one section during each cycle of said feeder part, character-
ized by: means for producing a reference pulse once per cycle of
said feeder part, means receiving said reference pulses and pro-
viding.therefrom a factor Q which represents the amount of cycle
degrees said feeder part moves in a given increment of time (e.g., .
Q = degrees of feeder part movement each millisecond), means
for adding said factor Q to a memory store upon the lapse of
each of said given time increments to provide an updated store
content, and means for comparing said cycle angle words of said ~:
stored elements to said updated store content to control the
occurrence of said switching events.
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From a different aspect, and in accordance with the
invention, there is provided a method for controlling a glass-
ware forming machine having at least one section including a
set of components controlled by an associated set o~ two-state
(on/of~) devices switchable between their on and off states in
accordance with a cyclically repeated sequential program of
switching events to cause said set of components to form a gob
of glass into an article during each repeat of said program, a
; memory means storing a plurality of elements defining a seq-
uential program of such switching events, each of said elements
including a cycle angle word indicating the cycle angle at which
an event defined by the element is to occur, and a feeder with
a cyclically movable part which feeder provides a gob of glass
to said one section during each cycle of said feeder part,
characterized by: producing a reference pulse once per cycle of
said feeder part, processing said reference pulses to provide
; a factor Q which represents the amount of cycle degrees said
feeder part moves in a given increment of time (e.g., Q -
degrees of feeder part movement each millisecond), adding said
factor Q to a memory store upon the lapse of each of said given
time incremsnts to provide an updated store content, and com-
paring said cycle angle words of said stored elements to said
updated store content to control the occurrence of said
switching events.
BREIF DESCRIPTION OF DRAWINGS
Fig. 1 shows in schematic fashion the essential
elements which comprise in combination the control system of
the present invention.
Figs. 2 and 3 illustrate the threaded list logic of
the system.
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DETAILED DESCRIPTION
Referring now to Fig. 1, the glassware forming
machine to be controlled is shown at 10, and comprises a
plurality of individual sections arranged in-line, and each
section is adapted to produce glassware articles, and to
deposit them on a take away conveyor (not shown). The molten
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glass gobs are delivered to the blank mold side of each section
in a predetermined sequence from a feeder 12 which feeds gobs
to these sections in a conventional manner. The cycle of the
machine 10 (and of its several sections) is dictated by the
size and shape of the articles to be produced, and will vary
for different production setups. Although the rate at which
the molten glass gobs are produced does dictate the cycle time
of the I. S. machine, this cycle time need vary only slightly
once the machine has been set up for a production run. We
have found that such variations may be ignored during a machine
cycle, and the system to be described takes advantage of this
by sensing only the condition of a proximity switch 14, as a
once per feeder cycle pulse produced by some cyclically movable
part on the feeder. This design concept has facilitated the
control of the I. S. machine timing from a commercially
available function generator 16 and other digital computer
components, to be described, during the ~achine cycle without
reference to any continuously monitored shaft position or the
like.
2Q Still with reference to Fig. 1, a commercially
available minicomputer 18 has conventional processor, memory,
and input/output register means linked to one another so that
data can be stored for processing by the processor in accord-
ance with program means, which includes means for varying the
stored data from a console 2~. Preferably, the minicomputer
18 comprises a PDP-ll manufactured by Digital Equipment
Corporation of Maynard, Massachusetts. This computer is of the
general purpose digltal type and has an internal clock (not
shown) for timing purposes, and a UNIBUS architecture wherein
addresses, data and control information are sent along the
56 lines of the bus, indicated by the double arrow line in
Fig. 1. The PDP-ll UNIBUS architecture provides for bidirec-
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tional and asynchronous communication between the processor,
the core memory, and input or output devices as indicated in
Fig. 1. In order to permit all of these devices access to the
UNIBUS through the addressing system used, a priority structure
determines which device gets control of the bus when two request
use of the bus simultaneously. The asynchronous feature allows
the processor to perform data transfers directly between an ~ ;
input or output device and memory without disturbin~ the
processor registers.
All ~equencing is done by a programmed PDP-ll mini-
computer using a function generator and an external proximity
switch 14 located at the feeder 12 above the I. S. machine 10.
The processor measures and records the machine cycle time.
This time represents a machine cycle, and a constant Q is
calculated to correlate time to a unitary fractional part of
that machine cycle. At preset time intervals determined by
the function generatox, the processor CPU adds the factor Q
to the contents of a core store location (cycle counter).
This updated core store content is compared to the next element -
in a threaded or linked list also contained in the core store.
This list is composed of a number of elements. The
number of elements is determined by how many valves on the I.
S. machine are to be turned on or off, and how many times each
valve is to be turned on or off within a cycle. There is ~ne
element in the threaded list for each change of state of a
valve. Thus, if durin~ one I. S. machine cycle, a valve is
turned on twice and off twice, there are four changes of state,
requiring four elements. A typical I. S. machine has 21
valves per I. S. machlne section, and 8 sections per I. S.
machine. There are thus 168 valves. Each valve is typically
turned on and off once per machine cycle, with typically one
exception, that exception being the valve controlling the
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baffle mechanism on each section. That valve is typically
turned on and off twice during each I. S. machine cycle. Thus,
a typical I. S. machine has a threaded list containing 352
elements.
An element is composed of four memory words, and
each memory word is 16 bits in length.
Each element is set up as follows:
The first word contains the fractional part, or angle,
at which the valve state change is to take placeO This angle
is between 0 and 359.9 where 360 equals one cycle. The
second word contains information for operator display and
identification purposes. The third word contains the output
number and the state in which it is to be left (on or off).
The fourth word contains the memory address of the next element
in the threaded list.
The elements in the threaded list are arranged in
sequence by angle, that angle being in the first word of each -~
element.
Fig. 2 shows by way of example a five element
threaded, or linked list, wherein the first word of each
element comprises an angle stored in memory; the second word
comprises operator display information identifying the section,
event, and state (on/off); the third word comprises the output
or driver number and its state; and the fourth word comprises
the memory address of the next element in the threaded list.
An unused or blank element is also shown at F in Fig. 2, and
illustrates the unused core storage capacity of the mini- -
computer.
From gero degrees in a cycle, in~-the example given
in Fig. 2, the cycle counter is updated at a preset interval
determined by the function generator 16 by the addition o~
the constant Q. This new value of the cycle counter is then ~
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compared with the first word ~angle) stored in the next
element in the threaded list (element A in Fig. 2).
When the contents of the cycle counter core store
location in equal to or greater than the angle in the first
word of element A, the processor performs the operation called
- for by the third word (output 16 on).
The fourth word is read by the processor, when such
operation has been called for, to update a pointer, located
in core store, so that further comparisons can be made with
the first word (angle) of element B.
~his process is repeated for elements B, C, D, and
E in the threaded list of ~ig. 2. Element E continues the
cycle back through element A etc. Element F is not used,
; that is this element is not in the threaded list.
O To change the angle at which a particular event
takes place, the operator, ~ia the operator's console,
I! enters information describing the new angle with reference
i' to a particular element if he merely wants to vary the
sequence within a particular cycle that this event is to
occur~ This information causes the following changes in the
threaded list:
A search for the element in the threaded list which
pertains to the given event takes place (element D in our
example). Upon finding the element, the CPU searches core
store for an unused element (element F in Fig. 2). The CPU
next copies all the information in words two and three from
the old element (element D) into words two and three of the
unused element (element F). The new angle is put in ~he
first word of the unused element (in Fig. 3, 315). Next, ~-
the CPU searches the threaded list for the proper inser~ion
place for the new element. By changing the linkage of the
threaded list, the new element is linked into the list, and
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the old element is excluded from the linkage and marked
as unused.
The preferred minicomputer currently used for
practicing the above described invention is the DEC PDP-ll,
not only because it is well suited to perform the above
described operations when provided with the factored clock
signal Q from the function generator 16, but also because
DEC has recently introduced ~o the trade a compatible sub-
~; system, the ICS-ll which provides a separately housed source
of input/output modules, which can be located adjacent to the
I. S. machine and feeder, and which still comprises a con-
tinuation of the UNIBUS architecture such that these modules
contain circuitry for addressing, encoding, decoding,
interrupt control and servicing, as well as data multiplexing
and transfer. Thus, the proximity switch 14 data signal is
encoded and fed to the UNIBUS through an input card in the
! module 26, and emergency stop manual switches on each section
of the machine are also so received in the system. So too
are the start/stop sequence control switches, and the gob
delivery switch for each section as indicated at 28. The
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emergency, and normal shut down sequences are stored in
memory for controlling these modes of operation in addition
to the normal operating mode described above, and so too is
the start-up mode, and the gob deliverymode, which introduces
hot glass to each section after checking a machine set-up
upon preparation for production of a particular size and shape
of glassware. The subprogrammed, selectively addressable
sequences are described in one or more of the U. S. patents
listed above, and need not be described in detail herein.
- U. S. Patent No. 3,905,793 discloses these subprograms, and `-
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is incorporated by reference herein. ~
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