US3628025A - Photoelectric control device - Google Patents

Photoelectric control device Download PDF

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Publication number
US3628025A
US3628025A US4583A US3628025DA US3628025A US 3628025 A US3628025 A US 3628025A US 4583 A US4583 A US 4583A US 3628025D A US3628025D A US 3628025DA US 3628025 A US3628025 A US 3628025A
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US
United States
Prior art keywords
tubular film
trigger
control
photoelectric
photoelectric devices
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US4583A
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English (en)
Inventor
Franz Kieferle
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Lonza AG
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Lonza AG
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Filing date
Publication date
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/92—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92019—Pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92114—Dimensions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92247—Optical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92323—Location or phase of measurement
    • B29C2948/92428—Calibration, after-treatment, or cooling zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92514—Pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92609—Dimensions
    • B29C2948/92619—Diameter or circumference
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92819—Location or phase of control
    • B29C2948/92923—Calibration, after-treatment or cooling zone

Definitions

  • a photoelectric control device in a tube inflating device comprises a light source directed to a series of photoelectric elements each associated with a trigger. Each trigger, except that of the element at one end of the series has a blocking device arranged in response to response of its trigger darkening of its photoelectric element. to operate the trigger of the next photoelectric element in the direction of said end.
  • This invention relates to a photoelectric control device for controlling the position of one limit of a dark zone having two limits which always lie between the limits of a distance which also represents the range of control.
  • Photoelectric control devices e.g., for level control, are known wherein a photoelectric scanning device (light box) follows one edge of a dark zone whose other edge lies outside the range of control.
  • Previously proposed devices of this type have a follower wherein the beam from a light source follows the movements of one limit of the dark zone. If the other limit of the dark zone lies within the control range, this previously proposed follower arrangement cannot be used, since the follower device is uncertain when the light box is outside the dark zone.
  • the present invention provides a photoelectric control device for controlling the position of one limit of a dark zone having two limits which always lie within the limits of a distance which also represents the range of control, the device also having means to measure this position, wherein photoelectric elements are disposed in a series along the distance forming the range of control at a mutual spacing such that at least one of the photoelectric elements always lies in the dark zone, and each photoelectric element has a respective trigger responsive to darkening of its photoelectric element, thereof, the triggers each having an output current which assumes a constant value, and the output jointly fonning the measurement value, each trigger, with the exception of the trigger of the photoelectric element at one end of the series, controls a respective blocking circuit which on response of its controlling trigger also operates the trigger of the next photoelectric device in the direction of said end of the series in the same manner as a darkening of said next photoelectric device, so that the triggers of all the photoelectric devices following a darkened photoelectric device in the said direction also respond.
  • This control device can be designed for instance as a twopoint or multipoint controller, or as a continuous controller for controlling a constant or for program control.
  • This control device is preferably used in a device for inflating tubes of sheet material, especially thermoplastic material, in order to control the tube diameter by affecting the inflating air inlet and/or outlet.
  • the present photoelectric device may be included in a tube inflation device with the series of photoelectric devices and a light source directed towards them so disposed that, in use, the inflated tube protrudes into a divergent light beam projected by the light source towards the series of photoelectric devices, and an adjustment motor actuated by the photoelectric control device for adjusting a control valve in the inlet and/or outlet air feed to the tubular foil.
  • the light absorption of the transparent and extremely thinwalled tube may be so slight that all the light beams which pass through the sheet material along the chords of the tube cross section, i.e., which pass through the sheet material twice, are hardly weakened.
  • the photoelectric control device responds to changes in the position of this narrow band of darkness (whose two boundaries lie between the ends of the series of photoelectric elements) caused by changes in the diameter of the tube, and adjusts the adjustment motor for the control valve in the inlet and/or outlet air feed to the tube in order to keep the tube diameter constant.
  • FIG. 1 is a partial layout of photoelectric means for controlling the tube diameter by acting on the inflating air inlet and outlet, for instance through the inflation head, in a device for inflating tubes;
  • FIG. 2 shows details of the electrical circuiting of the device of F K]. 1.
  • an air feed blower 1 is provided for forcing fresh air into a pipe 2 which contains a control valve 3 and which can be brought by a normally closed valve 4 into communication with the external atmosphere and through an inflation head 5 into the interior of the tube 6 of sheet material (shown in cross section) in order to inflate this tube.
  • the device for inflating tubes also has an extractor fan 7 which draws air out of an exhaust conduit 8 leading from the interior of tube 6 at the inflation head 5, in order to extract vapors (e.g., of plasticizer and lubricant) from inside the tube.
  • the exhaust conduit 8 contains a manually adjustable exhaust valve 9 and can be brought into communication with the external atmosphere by a normally closed valve 10.
  • the control valve 3 is adjusted by an adjustment motor 11 in the photoelectric control device to be described in detail below.
  • the photoelectric control device has in this instance 16 photodiodes 12a-12p disposed, in a series corresponding to the control range in a transverse plane of the tube 6, opposite an illumination device 13 which emits a divergent beam 14 towards the photodiodes l2a-12p.
  • the photodiodes 12a-12p and the illumination device 13 are disposed so that the inflated tube 6 projects into the light beam 14.
  • the distance between the photodiodes 12a-12p is such that at any moment at least one of them lies in the dark zone corresponding to the weakened part of the light beam. This is possible, in spite of the weakened part of the light beam near the tube tangent being very narrow, since the beam 14 is divergent, so that the dark zone is broader in the region of the series ofphotodiodes 12a-l2p than in the region of tube 6.
  • the illumination device 13 comprises a point-source lamp 15 in front of which rotates a disc 17 formed with a ring of holes and driven by a synchronous motor 16, in order to produce intennittent light with a frequency of 400 cycles per second, which enables AC amplifiers to be used for the photocurrent from the photodiodes l2a-l2p, and whereby the influence of extraneous light can be excluded.
  • Each photodiode -121 is provided with a cylindrical hood 18 in the form of a tube directed towards the lamp 15.
  • each photodiode 12a-12p responds only to light coming directly from the lamp l5, and the difficulties are avoided which could occur if light reflected at the tube 6 were to fall on one or more of the photodiodes 12a-l2p.
  • Each of the photodiodes l2a-l2p is connected to an AC amplifier 19a-l9p, for 400 cycles/sec, whose output feeds a trigger 20a-20p and is also connected to one pole of a six-pole switch 21, which by means of a voltmeter 22 permits a check to determine which of the photodiodes are illuminated and which are not illuminated, i.e., are lying in the dark zone, at any moment, using corresponding amplifiers.
  • Flg. 2 shows only the amplifiers 19a, 19b, 19c, 19p and triggers 20a, 20b, 20c, 20p of the first, second, third and sixteenth photodiodes 1211,1217, 12c, and 12p.
  • Each trigger responds to darkening of its corresponding photodiodes by delivering a constant output current when the intensity of the light falling on the respective diode has not reached a predetermined threshold value.
  • the total of these output currents of the triggers 20a-20p constitutes the control value which, as further described below, is used to produce an adjustment setting signal.
  • each of the triggers 20b-20p controls a respective blocking circuit 23b-23p which on response of its perspective trigger also operates the trigger of the photodiode which is next in the series.
  • the trigger 20c controls the blocking circuit 230 so that when photodiode 12c of the trigger 20c is darkened, the constant output current of the trigger 20c is applied to the blocking circuit 23c, which in turn causes the trigger 20b to respond.
  • the blocking circuit 20b then, in the same way, causes the trigger 20a to respond.
  • each trigger comprises a monostable multivibrator with two transistors 24b and 25b and is controlled by a full-wave rectifier 27b (not shown in FIG. 1) supplied from the output 26!: of the corresponding amplifier 1917.
  • each blocking circuit has an amplifier stage with a transistor 28b, 28c, and a zener diode 31b, 32b, or 31c, 32c in the input 29b, 29c and in the output b, 30c.
  • the input 29!) of blocking circuit 23b is connected to the output 33b of trigger 20b, and the input 29c of paralysis circuit 23c is connected to the output of trigger 200.
  • the additional input 34b is connected to the base of the second transistor 25b the monostable multivibrator of trigger 20b, and in the blocking function converts this transistor into the conductive condition, which corresponds to darkening of the respective photodiode 12b.
  • the output 30b of the blocking circuit 23b is connected to a blocking input of the trigger 20a (FIG. 1) corresponding to the additional input 3412.
  • the outputs of all the triggers 20a20p are jointly connected to a comparison circuit 35 wherein the sum of the trigger output currents which forms the electrical control value, is compared with an electrical value, adjustable to equal the desired control value, producing an output potential whose magnitude and polarity depend on the difference between these values.
  • This control difference can be read oil on a meter 36 and fed to a Pl-controller 37 which provides at its output an adjustment signal which is partly proportional to the control difference and partly proportional to the time integral of the control difference.
  • a Pl-controller is a proportional and integral action controller, that is, a combination of a proportional action controller with an integral action controller, known in the art as disclosed in the book Brockhaus der Naturwissenschaften und dertechnik, Wiesbaden l960, page 459.
  • a switch 38 feeds the output potential of the Pl-controller 37, which forms the adjustment signal, or else a potential taken from a potentiometer 40 supplied from a DC-source 39 and used for manual control, to a control valve 41 which controls the motor 11 to adjust the valve 3 in accordance with the adjustment signal.
  • a voltmeter 42 with a switch 43 is provided, whereby either the output potential of the Pl-controller 37 (adjustment signal) or the output potential of the manual controller 40 (potentiometer) can be measured, in order gradually to match the latter to the former manually before the switch 38 is changed from automatic to manual control or vice versa.
  • the information is taken from meter 36 by observation by the operator and is used to guide manual control.
  • the exeiter coil of valve 4 is connected to the trigger (not shown) of the fourteenth photodiode 12n. If for any reason the diameter of the tubular foil 6 increases so greatly that one or more of 'the photodiodes l2n, 12o, 12p are obscured, the trigger 20n of photodiode 12n responds and also opens to affect the adjustment signal of valve 4, so that the air blown by the input blower 1 largely escapes into the atmosphere, and in general air is only withdrawn from tube 6 by the extractor fan '7, the tube diameter rapidly decreases, and bursting of the more air from the tube 6, while the air feed blower 1 injects more air into the tube which is therefore inflated faster and prevented from collapsing.
  • Apparatus for controlling the diameter of an inflated tubular film 6, comprising a plurality of photoelectric devices 12a-l2p disposed on one side of the tubular film 6 in a line extending laterally of the tubular film,
  • a light source 13 arranged on the opposite side of said tubular film 6 to direct a light beam 14 to said line of photoelectric devices l2a-12p,
  • tubular film 6 positioned to project partially into said light beam 14 in a direction from one end (end at 12a) to the other end (end at 12p) of said line of said plurality of photoelectric devices (120, 12p),
  • said photoelectric devices (12a-12p being arranged close together in said line so that at least one thereof is assigned to the sector of the said light beam 14 which strikes on the tubular film 6 immediately adjacent a tangent thereof,
  • trigger circuits 20a-20p each assigned to one of said photoelectric devices 12a-12p and responsive thereto, said trigger circuits having blocking inputs 34b,
  • said output 30b, 30c being connected to a said blocking input 34b of the other 20a, 20b of said two trigger circuits which is assigned to the other 12a, 12b of said two photoelectric devices,
  • each of said blocking circuits 23b23p being operable upon the control of said one trigger circuit 20b, 200 of the two trigger circuits assigned thereto when the output signal thereof corresponds to a darkened state of the assigned said one photoelectric device 12b, 12c to affect said other trigger circuit 20a, 20b in a manner corresponding to a darkened state of the photoelectric device 12a, assigned to said other trigger circuit 20a, 20b,
  • control circuit 35, 37 having an input connected to the output of each of said trigger circuits 20a-20p,
  • inflating means 5 having pressure control means 1-4, 7-10,
  • control circuit 35, 37 connected to said pressure control means to control the pressure within said blown tubular film 6 whereby a predetermined diameter is maintained throughout the blow tubular film.
  • Apparatus for controlling the diameter of an inflated tubular film as set forth in claim 4 in which a first airflow restriction means 4 is connected in said air pressure inlet means 1,2
  • a second airflow restriction means is connected in said air pressure outlet means 7.8 for control by a selected one 200 of 5 said trigger circuits assigned to a photoelectric device 12c positioned adjacent the said one end of said line of photoelectric devices.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
US4583A 1969-01-24 1970-01-21 Photoelectric control device Expired - Lifetime US3628025A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH104169A CH487459A (de) 1969-01-24 1969-01-24 Lichtelektrische Regeleinrichtung

Publications (1)

Publication Number Publication Date
US3628025A true US3628025A (en) 1971-12-14

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ID=4201071

Family Applications (1)

Application Number Title Priority Date Filing Date
US4583A Expired - Lifetime US3628025A (en) 1969-01-24 1970-01-21 Photoelectric control device

Country Status (8)

Country Link
US (1) US3628025A (de)
BE (1) BE744713A (de)
CH (1) CH487459A (de)
DE (1) DE1908134A1 (de)
FR (1) FR2029074A1 (de)
GB (1) GB1296962A (de)
NL (1) NL7000966A (de)
SU (1) SU376972A3 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3718823A (en) * 1970-11-11 1973-02-27 Tokyo Shibaura Electric Co Optical detectors for inspecting the condition of samples
US3900738A (en) * 1973-05-23 1975-08-19 Lockheed Missiles Space Non-contact measuring gauge
EP0224240A3 (en) * 1985-11-26 1988-01-13 Bernd Becker Apparatus for the control of an installation for the manufacturing of extruded sections
US4748563A (en) * 1984-02-10 1988-05-31 Anthoine Gilles G Have invented certain new and useful improvements in method and apparatus for controlling the lift travel of a mast or derrick
US4877954A (en) * 1986-09-22 1989-10-31 Arnold I. Neuman Light counting system for convex articles

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2947916A1 (de) * 1978-11-30 1980-06-19 Gloucester Eng Co Inc Regelgeraet fuer einen schlauchfolienextruder
JPS5769421A (en) * 1980-10-20 1982-04-28 Olympus Optical Co Ltd Position controller
DE3322761A1 (de) * 1983-06-24 1983-11-17 Günther Dipl.-Ing. 2800 Bremen Schultze Zeichenbrett mit beweglicher bespannung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3123217A (en) * 1964-03-03 Capsule inspection method and sorting machine
US3375377A (en) * 1964-09-21 1968-03-26 Barrows Martin Ralph Radiation sensitive multichannel pressure transducer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3123217A (en) * 1964-03-03 Capsule inspection method and sorting machine
US3375377A (en) * 1964-09-21 1968-03-26 Barrows Martin Ralph Radiation sensitive multichannel pressure transducer

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3718823A (en) * 1970-11-11 1973-02-27 Tokyo Shibaura Electric Co Optical detectors for inspecting the condition of samples
US3900738A (en) * 1973-05-23 1975-08-19 Lockheed Missiles Space Non-contact measuring gauge
US4748563A (en) * 1984-02-10 1988-05-31 Anthoine Gilles G Have invented certain new and useful improvements in method and apparatus for controlling the lift travel of a mast or derrick
EP0224240A3 (en) * 1985-11-26 1988-01-13 Bernd Becker Apparatus for the control of an installation for the manufacturing of extruded sections
US4877954A (en) * 1986-09-22 1989-10-31 Arnold I. Neuman Light counting system for convex articles

Also Published As

Publication number Publication date
CH487459A (de) 1970-03-15
FR2029074A1 (de) 1970-10-16
NL7000966A (de) 1970-07-28
BE744713A (fr) 1970-07-01
SU376972A3 (de) 1973-04-05
GB1296962A (de) 1972-11-22
DE1908134A1 (de) 1970-08-06

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