DE2230957A1 - Method, application and apparatus for generating an error signal - Google Patents

Description

Method, application and apparatus for generating an error signal . .

Priority: June 25, 1971; Switzerland; No. 9242/71 ~

The invention relates to a method for generating an error signal before the molding of a product, which by-one faulty process step of an injection molding used to produce something that can be put into a molten state Material is produced in a divisible mold cavity »

For the operation of injection molding machines for processing In a molten state material such as warm plastic or thermosetting plastics and the like, it is known various processing parameters prior to the

209853/1104

_ 2 -

cease processing and monitor this partly during processing, partly its monitoring results as Control or regulation variables for the production process of the To use injection molding machine «It has also been suggested to weigh the ejected products or to use them Monitoring of an ejection section below the injection molding tool to monitor the correct shaping of the product before closing the mold cavity again "

It has now been recognized, however, that all of these known control, regulating and monitoring devices do not represent completely defined quantities for the quality of the product produced. Rather, it was surprisingly found that a defined volumetric filling of the mold cavity is a decisive quality parameter in the injection molding of plastics. «Furthermore, it was surprisingly recognized that the temperature during the plasticizing process of the plastics alone is not the major factor for the perfect quality of the product together with the volumetric filling importance, but rather that the temperature within a narrow temperature range of the melt itself, as occurs when leaving a chamber through a nozzle during the injection in the mold cavity is important ₀

Because of these new, surprising findings in the Process steps for the production of products from in

209853/110 4

molten state displaceable material is the inventive feature of the method that at least during a volumetric filling of the mold cavity with on ge ·, molten material a deviation from a specified, possibly tolerance-afflicted, nominal value a measured value and the measured value is used to generate an error signal will.

Veiter can in addition to the volumetric filling of the mold cavity also a volumetric melting of in molten liquid Condition .. material to be moved in the event of deviations from a volume Irish target value Generate error signal »,, ■

In addition to the specified possible deviations, Veiter can a measured deviation in temperature during volumetric filling of the mold cavity will generate an error signal O

The invention further relates to an application of the method which is characterized in that the error signal triggered during the manufacture of a product for detection and / or marking the product when it is being removed from the divided mold cavity »

The invention further relates to a device for carrying out the method, comprising an injection molding machine with a

209853/1104

controlled to be operated mold clamping device for receiving the mold cavity for products forming parts of the Injection molding tool and with an injection molding unit, consisting from an injection molding nozzle that can be connected to the mold cavity of the injection molding tool, one to the injection molding nozzle Subsequent, in volume variable chamber for collecting molten material, one on the in molten liquid Condition displaceable material acting temperature control device and a changing the volume of the chamber Injection device, as well as with a control device connected to the injection molding unit, soft for operation the.injection molding machine.adjustable measuring and control devices contains. This device is in accordance with the invention characterized in that the injector is a modifying of the volume of the chamber imaging Y / e knife device, with Means for generating an absolute measured value of each movement between two successive changes in direction of the Injection device are assigned, the displacement measuring device with the means for generating the measured value with a target value specification Device provided setpoint value-measured value comparison device is assigned in the control device, and the setpoint value-measured value comparison device with an error signal device intervening in the control of the operation of the injection molding machine is provided "

209853/1 10 *

_5-223Ü957

The apparatus having a source connected to the injection unit tempera door measurement device can at least one temperature measuring probe in the region of the chamber or, "the subsequent to the chamber Spritzgiessdüae for direct contact include with material which / is else connected to the error signal device in a suitable V ₀

The device can furthermore have a guide device provided with a reversing device in the ejection area of the product, wherein the reversing device can be functionally connected to the error signal device _e

The error signal device can be connected to an optical and / or acoustic error signal display device _{or the like}

The error signal device can be functional with the controller be connected to the mold clamping device.

The device can be assigned a storage container provided with a metering device, which metering device can in turn be functionally connected to the error signal device _e

In functional connection with the position measuring and the guide device an ejection control device can be provided «, This allows a determination of the productivity,

An intervention switching device can also be installed in the error signal device to be activated *

209853 / 11OA

When injection molding method, a separable Spritzgiessverkzeug is closed as the first stage, thus forming a Fo-rmhohlrauin ο Through the unigebende the mold cavity wall of the injection mold cause one or more Punktangüsse or film gates β These may be associated with an injection molding nozzle of a Spritzgiessaggregates ₀ to Carrying out the injection molding process, an injection molding unit is provided in addition to the injection molding tool, which has at least one plasticizing device and an injection device

has »The injection device comprises an element which allows the volume of a chamber to be changed, which is very often done by a hydraulic piston lifting unit, this is to ensure the product-appropriate plasticization Injection molding unit generally provided with a temperature control device which allows both heating and cooling «, Such a temperature control device is in a known manner with temperature measuring devices and temperature control devices Mistake.

For the operation of an injection device, it is previously known To do this, specify the drive force, if necessary zone by zone, and define the injection path using limit switches «,

Now to a decisive improvement of the injection molding process to get, instead of the previously known limit switch actuation during the filling of the mold cavity a volumetric filling carried out for this are the most important

209853/1104

known, fixed cross-section of the chamber of the injection molding unit on the one hand and the stroke of the injection device to reduce the volume of the chamber on the other hand, the decisive variables ₀ This means that it is primarily important to proceed the height of the injection device by a setpoint and by a stroke measurement device to "determine" each time, in particular by means of a setpoint / actual value comparison control. This means that each process called generally "shot" for filling the divisible IOrmbohlrr ^ iaOfs with material set in a molten state is determined from any desired shot movement point away over a predefined distance. In contrast to previously known devices with fixed end stops, this allows much greater accuracy in filling the mold. These more precise mold fillings lead to products of very high quality «

The effectively injected one gives way due to any interfering influences Volume of molten material into the mold cavity from the V / ert that may be specified with tolerances then an error signal is triggered. This error signal can generate control signals for two functions, either for Actuation of a marking stamp provided in the injection molding tool and acting on the product, so that after the Forming such a product this is immediately recognized as scrap quality, or that in the ejection area of the Injection molding tool an arrangement is made to the

209853/1104

particularly to capture low-quality product and to feed the waste, which may be returned to production in shredded form "

For further influencing the quality of the products was also recognized that the ruling during filling of the mold cavity temperature of fond state accumulated material plays a more surprisingly large quality-determining importance in melt flow! ,, Here £ ^ö nügt previously be ~ knew array of tempera door probes only not in the injection device wall that receives the plasticizing tool. Rather, it is necessary to arrange this temperature measuring probe in the area of the chamber receiving the atifschmolzene material during the plasticization in such a way that the effective product temperature can be measured during the entire shot process appropriately adapted mounting the effective temperature of the air flowing in the molten state into the mold cavity mass can be measured ₀ These effective temperature readings of the material during the injection process, d _o h ₀ during volumetric filling of the mold cavity, a measuring device is supplied, which in addition ein.gegebenenfalls subject to tolerances Setpoint is switched on. As experience shows, temperature deviations from a target value result in products of poor quality as well as inadequate volumetric filling of the mold cavity

209853/11 (K

G-around is a detected deviation of the Temperattir-Is · - value dor schmelzflussigen mass from a temperature set point or a corresponding deviation outside the tolerance range of a Tcmporatur setpoint stock during volumetrisehen lOrmfüllens the error signal device supplied ₀

The error signal device is not only used for optical or acoustic error signal triggering but can just as well used for functional intervention in the operation of the injection molding process or the injection molding machine will.

Thus, there is a first possible application of the functional Use of the error signal in that one resp. In the ejection area of the product from the injection molding tool. from its Mold cavity provides a detection device such that the faulty product is switched off from the actual production ο

A writing instrument can do much more with the error signal device be connected, above all the setpoint-actual value deviation record "

The use of this equipment allows the type and time of faulty production processes to be determined at any time. This means that production defects can also be recorded at a later date. In addition, such a writing instrument, which by

209853/1104

the error signaling device is controlled, at any time the productivity of the plant, ie _{0 to determine} the ratio of error-free to error-prone and from the carrying to unproductive or dead time of the production plant *

An embodiment for performing the method is from the attached drawing which

in der- Figo 1 an injection molding machine in a general representation and

in FIG. 2 the essential elements for carrying out the method on an enlarged section of the injection molding machine shows* . · ".. · ■. · ■

The injection molding machine 1 consists of a molding press for opening and closing a divided injection mold 5 »4, a plasticizing and injection unit 5 with associated heating and / or cooling elements 6, a raw material container 7, a drive unit required for the plasticizing device and one for injection the plasticized mass in the split mold 3,4 necessary shift unit 9 _O the machine veist a control apparatus 10 for the controlled execution of the movement sequences to "the split mold 3,4 is actuated by a press 2 associated Schlieusaggregat 11" in the plasticizing and injection unit 5 a plasticizing cylinder 12 is provided with a collecting space provided in the area of its spray nozzle 13 *

209853/1104

_-11m 223U957

Between the raw material container 7 and the plasticizing cylinder 12 is a metering unit 15 with an associated speed variable Dosing motor 16 built-in

In the area of an axially displaceable and rotatable drive shaft 20, which extend from the sliding unit 9 to one in the plasticizing cylinder 12 contained plasticizing device extends in the axial direction, is a limit switch 21 and on the Drive shaft 20 a squat 22 actuating this is provided »

A very fine toothed rack 25, which can be displaced synchronously therewith, extends parallel to the drive shaft 20 and which a displacement encoder 26, the pinion 27 mrt of the rack 25 in Intervention stands, is assigned.

In the collection chamber 14 in the region of the spray nozzle 13 into it a temperature sensor 30 extends _e

In the ejection area from the divisible mold 3 »4 there is one Slide 35ο This slide is with an adjustable flap 36 provided, to which an adjusting drive 37 is assigned; Two outlet sections 38 and 39 lead away from the flap 36 to two Receiving stations 40 and 41 »In the present example, these are designed as containers. Instead of this container you can but also conveyor units are provided, on the one hand to further processing or packaging stations and on the other hand lead to scrap recycling facilities,

209853/1 104

- BATH

223Ü957

Conductor OO lead to ground potential, A current source 50 supplies primary energy via conductor 51 to a forward path selector ev, a return path selector sr, an intervention switch IS, an error signal device PS, a setpoint temperature transmitter ST, a temperature control device TST, a changeover switch 52 in a fault switching device PU ₀

The error signal device PS comprises a reject control device A, a temperature control device TR and a dosing control device D. A signal lamp 55 » a horn 56, a writing implement SCIIR and a solenoid of the fault switching device PU connected.

At a pre-travel difference detector Dsν are through a line 61 of the Vorlaufwegwähler sv, through a line 62 the Reject control unit A and through a line 65 the displacement encoder connected.

To a return path difference detector Dsr are through a Line 71 of the return path selector sr, through a line 72 of the dosing controller, thereby a line 75 of the limit switch 21, through, the line 63 of the displacement transducer 26 and through a line 74 the reject control device A connected "

Two lines 81, 82 lead from the dosing controller D to the dosing motor 16,

The temperature sensor 30 is connected to a temperature difference detector DT through a line 91 and the temperature sensor 30 through a line 92.

209853/1104

temperature controller TR and through a line 93 the setpoint temperature « ST encoder connected »For one of the heating and / or cooling elements is a connection through a conductor 96 to a temperature controller TST and from this through, a line 97 to the temperature controller TR shown »For the further heating and / or Cooling elements 6, additional devices of the same type can be provided «

Two lines lead from two connection parts of the switch 52 101 and 102 to swivel drive 37 »To line 102 and connected to the machine control system 10 by a line 122 a productivity determination device PB is provided »

The machine control system 10 is connected to the error signaling ^{device I 1} S by a line 110, "

This device allows the implementation of the method steps explained above, in particular the following results Features: '

During the plasticizing of the material, by a shear work of the plasticizing tool moved by the drive unit 8 in the plasticizing cylinder 12, the metering motor 16 is in Set speed also driven to get out of the raw material container 7 The material to be plasticized is dosed into the feed zone of the Pias tif izierwerkzeuges to promote. Melted Material collects in the area of the nozzle 13 * During the plastifi The plasticizing tool and thus the axis 20 are decorative work

2 0 9 8 5 3/1104

of the injection unit 9 to the rear, that is to say moved by the injection nozzle 13 ViGg «, during this movement is through. the rack 25 moved in parallel thereto moves the pinion 27 of the transducer 26. In accordance with the V / eg covered, the V / eg transmitter 26 emits a sequence of pulses via the line 63 to the return path “difference determiner Dsr”. At the end of the plasticizing work, the machine control 10 triggers the shot. Thus, a movement of the plasticising ~ tool through the shift unit 9 is triggered by the drive shaft in the direction of the injection nozzle 13 * During forward "motion is the displacement sensor 26 _f by" the rack is set 25 via the pinion gear 27 in drainage, a pulse train via the line 63 to the advance path difference detector Dsv from "This compares the pulse sequence with the pulse sequence _{0 emitted by the advance path selector sv via the line 61} This reject device generates an error signal in the line 53 _f that the signal lamp 55 »the horn 56 and the reversing magnate 57 of the error switching device FU excited with the line 102 _o The adjusting drive 37 we d excites and pivots the deflecting flap 36 from the illustrated right to the left position. When the mold is opened, the product falls into the

209 8 5 3/11 OA

Chute 35 and exits through the outlet section 39, the engine into the collection vessel 41. From here, the rejects are a reject recovery supplied _o Alternatively, the Fehlerumsehaltgerät FU from the line 102 to leave a excitation current to a marking device 113 away via the line 112, which a marking die 114 presses into the product so that a defective workpiece is immediately identified during a subsequent quality control «,

In parallel, the error in the productivity determination device PE enumerated, this being fed by the machine control 10, as a function of time, an impulse for each shot that has taken place will·

During the injection process, the temperature of the plasticized material injected into the mold cavity through the spray nozzle 13 is effectively determined in direct contact and this measured temperature is brought to the temperature difference detector DT through the line 91.This DT compares the measurement result with the target temperature -Sender ST and value delivered by line 93 «. In the event of any deviations, a signal is sent through line 92 to the temperature controller TR in the error signal. direction FS which in turn sends a control signal ^ ₄ .

ο via line 97 to the temperature control device TST _o . «-

This causes a change in the heating or cooling ^

no one or more elements S ₀ At the same time an error °° occurs

signal to the reject device A, which the ° described above Error signaling and control triggers «,

In the "cases where injection must be carried out against the stop, the ■ hoioat, then the plasticizing tool in the foremost position.

is moved, the following device is used:

At the end of an injection process, the plasticizing tool and thus the switching cam 22 are in the foremost position. In this, the limit switch 21 is actuated. With the start of plasticizing, the switching cam 22 moves away from the limit switch 21 ₀ This switching of the limit switch sends a control signal through line 73 to the return path difference detector Dsr also to the same return path difference determiner Dsr. During the Piastifizierung now compares Dsr arriving from the encoder 26 pulses with the sr from Rücklaufwegwähler predetermined pulses _o If at the end of Piastifizierung a difference between the number of pulses from the V / eggeber 26 and those sr from Rücklaufwegvähler, then the return path difference investigators Dsr outputs an error signal through the line 72 to the dosing controller and a further error signal to the Axlb shot device A. For the subsequent shot of plasticized material in the mold cavity, the reject device of the error signal device sends an error signal to the signaling, writing and control devices 55,56, SCIiR and FU _e The product is either marked and / or removed from production. The dosing controller D changes the speed of the dosing drive 16 so that the next dosing work is corrected as required,

209853/110 / »

To intervene in the work flow of the injection molding machine at any time to be able to take is an intervention switch IS intended. According to different positions can be used in particular for set-up work, but also to carry out Corrective measures in the course of a production influence be taken, with the Pe hler signal device FS for example all difference determiners are switched off and the operation can be controlled purely from the machine control. These interventions can be done on the writing instrument SGHR also recorded or marked *

At the productivity determination device PE is at all times the ratio of total work to productive work can be seen by marking all faulty production cycles separately become »This allows the plague at any time Profitability of a certain production process that any necessary early intervention in production, an inspection of the tool or the injection molding device.

- Expectations -

209853/1104

Claims (15)

- 18 claims lJ method for generating an error signal prior to shaping of a product that has been damaged by an incorrect process step an injection molding used to produce a material that can be converted into a molten state into a divisible one Mold cavity is produced, characterized by σ e k e η η that at least the filling of the mold cavity with melted iiacerial volumetrically by a set point specified and then carried out) and a deviation from the specified, possibly tolerant setpoint Measured value generated and the measured value generating an error! Cmals causes. 2. The method according to claim 1, characterized in that that in addition one during a volumetric melting of material which can be brought into a molten state deviations from a predetermined, possibly tolerance-afflicted, volumetric setpoint generates an error signal 3. The method according to claim 1 or 2, characterized in that in addition one of a voraeciebcnen, optionally tolerance-afflicted setpoint cjemeasured deviation of a temperature of the melted material during a volumetric filling of the mold cavity generates an error signal. 209853/1104 4. The method according to any one of the preceding parts, thereby marked that the bed. the manufacture of one Error channel triggered by the product for recording and / or marking of the Erzeuanisscs when molding from the divided mold cavity is used, 5. Device for performing the method according to one of the preceding claims' with a Soritzgießmaschine with a controlled to be operated mold clamping device for recording the parts of the Soritzgießwerkzeuges which form the mold cavity for products and with an injection molding unit, consisting of one which can be connected to the mold cavity of the injection molding tool Snritz casting nozzle, one connected to the SoritzgieP. Variable volume chamber for collecting molten material 'one on' that which can be brought into a molten state Material-acting TemOeriervorrichtuna and a Einsoritz device changing the volume of the chamber, as well as a the injection molding unit connected to the control device, which for the operation of the injection molding machine adjustable measuring and Contains control devices, characterized in that (5.9)
of the Einnritzvorrichtuna / a changing the volume of the (14) (25) (26.27) Chamber / imaging displacement measuring device / and means / for generating an absolute measured value of each movement between two successive changes in direction of the injection device are assigned to the Weameßvorrichtung with the means for (Sv; Sr) Generation of the measured value of a setpoint specification device / (Dsv; Dsr) see setpoint value comparison device / in the control device 209853/1104 223Ü95? - 2ο - Richtuna is assigned, and the target value measured value comparison device with one in the control of the operation of the (1) (PS) Injection molding machine / a ready-to-use error analysis device tnna / ver is seen . 6. Apparatus according to claim 5 with a to the Spritzaießaggreoat connected temperature measuring device, characterized in that at least one temperature measuring (3o) (14) probe / in the area of the chamber / or. who connect to "the chamber- P3) the Snritz nozzle / for direct contact with the collected melt liquid material is built in and this temperature measuring probe (DT) by a setpoint / actual value / temperature comparator / with the (FR)
• Error signal device is actively connected. . ... 7. Device according to claims 5 or 6, thereby α e k e η η - (35) indicates that in the AusA>; urf area / of the product (34) (36) the injection molding tool / a guide device / is provided, the (37) Control device a change drive / riit a reversing advance (FU) ·. direction / is assigned and this Umsteuer-Vorrichtunn functional (FS)
is connected to the error signal device. 8. Device according to one of claims 5 to 7, characterized marked, that with the error channel device (FS) (55) tion / an on-site / and / or acoustic ^P ehlersianal display device - "(56) tuna / is connected. 209853/110 /, ⁸ ^ 0 ^{R! GlNAL} 9. Vorrichtuna according to one.der claims 5 to 8, characterized. -that the error sicmal device (FS) (2) Functionally connected to the control of the mold clamping device that is. 10. Device according to one of claims 5 to 9 with a Storage container for material to be melted, on which an in the Snritzaießaaaregat promoting dosing device with associated Drive device is arranged, characterized in that the Fehlerianal-Vorrichttmg (16) (15) functional with the drive device / the dosing device / ver is bound. 11. Device according to one of claims 5 to Io, characterized marked that 'in functional connection (? 5) ⁽³⁶⁾ with the Wenmeßvorrichtuncy and the control device / assigned an ejection control device is provided. 12. The apparatus according to claim 11, characterized in that the ejection control device with a (PE) "Productivity determination device is provided. 13. Device according to one of claims 5 to 12, characterized characterized that one in the error signal pre (IS) "direction-acting intervention switching device / provided 209853/1104 14. Vorrichtuna according to one of Ansorüche 5 to 13, thereby (SCHR) q e indicates that a writing device / to the (FS)
Error signal device is connected. 15. Device according to one of claims 5 to 14, thereby q indicates that several injection molding machines (1) with selective measured value evaluation of a single, central error)
Siimal-Vorrichtunq / are assigned. 209853/1104 · «crisim«.