DE2803838A1 - DETECTION DEVICE FOR MOLDING DEFECTS IN A PLASTIC INJECTION MOLDING MACHINE - Google Patents

Description

Detection device for molding defects in a plastic injection molding machine

The invention relates to a detection device for molding defects in a plastic injection molding machine and in particular on a detection device for molding defects, at dep a faulty casting by monitoring the length the time is determined during which a piston of the injection molding machine within an injection molding stroke of running from one point to another.

In plastic injection molding machines, a piston runs from the injection molding start position to the injection molding end position during the injection molding process. If the injection molding start position is, for example, P ₀ and the injection molding end position Prp in FIG. 1, the piston (not shown) runs from Pq to Prp and returns to Pq when the injection molding is terminated. In the continuous operation under the same molding conditions as long as normal injection molding is effected, the relationship between the distance and time in an injection molding stroke is substantially constant as the piston moves from the injection molding start position to the injection molding end position. An example of this relationship is shown by a solid line A in I ¹ Ig. 2 & £ &% i & iii PÄ ^^ Wt? during the the

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Piston passes through a point Ρ ,, a distance I ^ away from the injection molding start position Pq, has an essentially constant value t ^ during continuous operation and the position of the piston, ie the injection molding end position Pm at the time of the injection molding end tQ is essentially constant which corresponds to the distance Iq. If a faulty casting as a result of the niching of foreign parts in the synthetic resin, an unsuitable synthetic resin temperature or the like. expected, the relationship between the piston travel and time is not equal to the solid line A in Fig. 2, but rather similar to, for example, curves B and G. Curve B occurs when the piston is running fast and over for some reason the injection molding end position Pm. depending on the circumstances. Curve G occurs when the piston is running slowly and does not reach the injection molding end point Pm _{at time t Q.} Defective molding can therefore be detected by paying attention to the relationship between the piston travel and time.

A conventional molding defect detection device comprises a limit switch Sq which is turned on when the piston starts injection molding, a switch S ^. Which is turned on when the piston passes a desired point Vy, located between Pq and Pm, and a switch S ₁₇ on, «Ler is switched on when the piston goes beyond Pm by a distance 1-g in order to detect when the piston has gone beyond Pm, the switches Sq, S ^. and S ₁₇ is in the one in S ¹ Xg. 3 are circuit arrangement shown. A timer 1 operates a contact 1a which is turned on when the timer is operated. Relays 2, 3 and 4 each have normally open contacts 2a, 3a and 4a and a normally closed contact 3b of relay 3

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indicates the passage of the piston through the point P ,,. In this conventional circuit, when the piston begins to move, the switch S _{Q is first} switched on and, at the same time, the timer 1 is energized with the start of movement. Since the timer 1 is set to a time t ** which is slightly longer than the time t ^ during which the piston usually moves through the point P _x i, the timer 1 is actuated to turn on the switch S _x i before the contact 1a is turned on in the case where casting is carried out smoothly. Then the relay 3 is actuated, whereby its contact 3a is switched on and holds it itself, while the contact 3b is opened and thereafter the relay is prevented from being actuated even if the contact 1a of the timer is switched on. By lighting up the lamp L is to confirm that the piston passed the point P _x , before the timer 1 was actuated, ie the time during which the piston passed the point P _x ] is less than t ^.

In the event that the piston runs slower and the timer 1 is actuated before the switch S _x . is switched on, the relay 2 is excited via the contact 1a of the timer and the normally closed contact 3b of the relay 3 is closed. Thereafter, the contact 2a is closed in order to operate the relay 4-, whereby the contact 4a is closed for its self-holding, and the relay 4- emits a casting error signal, whereby an alarm is switched on or an electromagnet is actuated, which is on a shooting device is arranged for sieving defective products. Even in the event that the plunger does not stop at the injection end point Pm and reaches the point P ₇ , the switch Sg is closed to turn on the relay 4, whereby the same effects as mentioned above occur.

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However, it has been found that if the time the piston passes through the point P ^ is shorter than the preset time t ^ of the timer, it is normal, and if the time is longer than the preset time, this is faulty. Especially in connection with Pig. 2 it was found that when t ^ equals t ^, the curves passing through a coordinate Y ^ or above, e.g., A and B, are normal curves, and one below the coordinate Y ^. running curve is a faulty curve. Although curve A or a curve practically in its vicinity are normal curves, curve 3 is an erroneous one. With the detection device described above, it is therefore impossible to detect faults caused by too "rapid movement of the piston".

In addition, a casting defect detection device is known in which the time measurement is started at that point in time becomes, when the plus pressure of the piston to "advance of the piston of the injection molding machine has reached a certain level, the time is measured during which the piston runs to the injection molding end position, and when the measured Time is outside the preset time range, an overly fast or overly alarming is released slowly. Different from the aforementioned detection device, this detection device also capture an excessively rapid condition. However, this device is designed so that the time measurement is started at the time when the liquid pressure has reached the certain level. It exists hence the risk of mistakes if the viscosity of the Molding material is changed e.g. during the injection molding stroke. A more detailed explanation follows later. Like this in Pig. 4- is shown, the relationship ζνάseheη is the Time and pressure of injection molding during normal

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Injection molding process with J, the relationship between the time and the path as E and the time during which the piston has reached the injection molding end position Iq after reaching the specific pressure hg as injection molding pressure, denoted by t ₂ , i. In contrast to what is stated above, the relationship between time and pressure is indicated by L in the EaIl where initially the viscosity of the casting material is low and the temperature of the metal mold is also low, or the viscosity of the casting material is low and the filling opening for the material in the mold is blocked by foreign bodies, and the relationship between the time and the path In the above cases is denoted by K and the measured time is t, ^ - In the case of the detection device of the described T ^ ps is the viscosity of the material originally low and the piston runs fast. The curve M is therefore above the curve K. If the temperature of the ketallic mold is low or the filling opening of the mold is blocked by foreign parts, as a result of which the piston runs slowly and therefore the curve M falls below the curve K, then the time during which the injection pressure hg achieved delayed by ^ t and during which the piston reaches the time the Spritzgießendstellung 1 _Q is also increased by t ^ ₂ delays. If At ^ and At _{2 are} substantially equal in magnitude, then t ₂ ^ becomes t ^> ,, whereby the detection of defective casting becomes impossible.

The aim of the invention is to provide a detection device for casting defects that reliably detects a defective one Can be poured through a plastic injection molding machine.

The detection device according to the invention for casting defects has a first measuring device for measuring the time while driving which the piston passes through a first point preselected in the injection molding stroke of the piston, a device for

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Setting the upper limit value of the time limit for the first point, a device for presetting the lower limit value for the time limit: Mli ⁱ this harvest point, a device and if a G -ießfelilor-Signals, if the from the er ?, ban I'iüU-3i: iricätung enjoyed since τοπ the £ sl: -allowed ¹ .: v'L ;. ^ »; I;,; L: -: i .1 ^ n upper ^ iil lower Cia ^ j. ^ R *; ^ -,:, bv: ei ^! Ib _s "!;.-.-; *: - / ".; cit ^ He .: facility sur. IiSFS ^ - the Ζβύπ. viahread "- ^ c d-- ,: '-': ■ '^ lji through " ine :: s'v-iiti; -, she ": 7 -.- L" orntet: nnte - :::: ύ · ^ id-nd .n PiiÄt runs through, which in the Sprio ^ sießhub ü .. ^ "£ oi ^; oeas xoreinge-;? tollt is a JSinr-icV-tion to the Vcroinitellan dos obev'en cross-value of the casualness of time TiIr den ^ t- riding point, sine 3in. Ab. ^ B ^ a ei '.:? 3 Gießfet "β ^ - · 3? -ΚηΓ. ^Ί -ΐ instructs / Ουκ the sound of si / sr; - :. iiesssinrici. ^ ₁ Ui ₁ :;: 3 i. "... · v_- Z -: - it before ■ l - r 2tiü3uläL: e." i £, ^l: ^ t; ^ .; xsolien the v = ■ -.!. -; -.- e ¹ ^ -uc uUi-j: =., Grtna- '/ ertea abweiclrb «.

Jie Zeitaessungen uur ^ z. .-. Le first t. "Vl ^. / Oitc ilü-ög Λ-irdeu begun, v; snn a ^ r Eoibcn bi ^. its .Jpritsgieß tiI- art3c Q llung reflects _} or when the piston passes through a point. Preferably, the first and second hating means consist of counters for counting clock pulses supplied at the same time as the start of time measurement, respectively, while the means for presetting the upper fourth and lower values corresponding to the first and second points each consist of digital switches. Means should be provided to indicate the times measured by the first and second measuring devices.

The temperature of the metal mold into which the plastic material is poured is one of the peripheral factors

BATH ORIGINAL

The temperature of the metal mold changes as synthetic resin is poured into it. In the case of repeated production of the same type of castings, the temperature at a certain point on the metal mold becomes constant during the casting cycle. For example, the time between the start of injection molding and the next start of injection molding by the ram, that is, a screw or the piston, is regarded as one molding cycle, and the temperature ar at a certain point during each cycle is substantially constant. Preferably, therefore, the temperature at a certain point within the casting cycle is monitored in addition to monitoring the time measurements. For this reason, it is advantageous to have a device for detecting the temperature at a desired point of the ^ crr. during the casting process, a device for presetting ( ³ GS upper limit value of the temperature of the mold, ciue execution sum presetting of the lower limit value of the temperature of the mold and a device for emitting a temperature error signal if the measured standard temperature of the Range between the upper and lower limit values of the pre-set temperature deviates. The detection device for the normal temperature should emit a signal for the detected temperature as a digital word, while the devices for presetting the upper and lower limit values of the actual temperature each consist of digital presetting devices Means for displaying the temperature detected by the detection device for the Porm temperature can be provided as a digital value.

Gemil. - ■: ..-; ■ .: b £ ^v . ~ O: .-; ---. £ te: - 2 C = C ^ r ¹ : -. ': Is χ Srf i., :: u. ^: 2 :: .. V.. der Erfas3ui: g £ 3i; ... ^; ·;:; ■ ;;;:. j; z '\ ^ ^ :. 5.1fihlir _ ~' _ ". r · si.:- '_ .. /:; .- ■: ■■ material injection molding machine at least two desired points in the injection molding stroke of a piston or plunger in the injection -

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gußiaascliine preset, the times during the the ram runs through the respective points, are measured and a casting error signal is given if the measured times differ from those for the respective Points deviate from the preset time allowances. It is provided that the detection device for casting defects is used together with a detection device for a temperature defect, with which the temperature is measured at a certain preset point during the casting cycle and a Te opera door error signal is issued when the measured Temperature deviates from the preset limit.

The aforementioned and other features as well as objects of the invention will become apparent from the following description in conjunction with the drawings, in which the same reference numerals denote the same components. In detail shows:

Fig. 1 is a graph showing the positional relationship of the switches used to detect the position of the Ram or piston are provided in a conventional detection device for casting defects, shows,

Fig. 2 is a graph showing the relationship between the travel and time of the ram in the conventional embodiment shows

3 shows a circuit of a conventional detection device for casting defects,

Figure 4 is a graph showing the relationship between the injection molding pressure and the time and between the V / eg and the time in the conventional one Embodiment shows

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FIGS. 5 and 6 show the positional relationships of switches used in an embodiment of the invention are provided,

Figure 7 is a graph showing the relationship between the path and the time of the plunger or piston to explain how this works Embodiment shows "

8 shows an electrical circuit of the invention Detection device for casting defects and

9 shows an electrical circuit of the detection device for a mold temperature error at a certain point during the casting cycle.

In Fig. 5, a front form 34 mounted on a fixed plate 35 is shown. A movable mold 36 is arranged on a movable platen 37. The front mold 34 has a connecting channel 40 which is connected to a nozzle part 39 of an injection molding cylinder 38. A hopper 41 for a plastic material is provided in the middle part of the injection molding cylinder. One end of the plunger, tappet or piston 42 is molded onto a piston 43. This piston 43 is provided in a hydraulic cylinder 44, as a result of which the ram 42 can be moved back and forth in the injection molding cylinder 38. The plunger 42 can be rotated by a drive mechanism such as an electric motor not shown here. A ring 45 is attached to the central part of the plunger 42. _{Limit switches Sq 1} S ^ ₇ S ₂ actuated by the ring 45 are arranged along the stroke of the plunger 42. The positional relationship of the limit switches SQ ₅ S ^ ₅ Sg is shown in detail in FIG. A point P ,, at a distance 1 ,,

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of Pq and another point ~ 2 ^ at a distance l _p from Pq are preset between the injection molding start point Pq and the injection molding end point Pfj, of the plunger, and the switches S ^, and Sp are provided so that they are switched from the open to the closed state when the plunger passes through the respective points in the arrow direction shown. As previously described, the switch S _{Q is switched} from the open to the closed state at the same time as the plunger starts the injection molding process. This switch Sq can be arranged at a point at a certain distance in front of P ^ from the injection molding start position of the plunger, so that it begins the time measurement after the start of injection molding. In addition, the positions and the number of preset points for the time measurement can be selected as desired depending on the casting conditions. A pulse oscillator 5 oscillates at a certain frequency. A pulse emitted by the pulse oscillator is fed to a counter 7 via a blocking gate 6 which is closed by EIE signals from switches Sq, S ^. One type of display shows a counter reading X ^ of counter 7 digitally. In the same way, a blocking gate 9 can be closed by a ΞΙϊΤ signal from the switch S2, while a display 11 shows a counter reading Xp of a counter 10. An output pulse from the pulse oscillator 5 is given to the counter 10 via the lock gate 9. Digital presetting devices 12, 13, 14 and 15 are also provided. The presetting device 12 sets the lower limit value D, the point in time at which the plunger passes the pre-set point P ^, the pre-setting device 13 the upper limit value, the presetting device 14 the lower limit value, the point in time at which the plunger passes through the preset point Point P ₀ runs, and the gate setting device 15 its lower limit value. Multi

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plexers 16 and 17 and a subtracter 18 are also provided. Upon receipt of a timing signal TM, the multiplexer 17 selectively and successively switches the values DG that are preset by the digital presetting devices 12 to 15 in order to give them to the subtracter 18, for example, and to repeat the previously described mode of operation Multiplexer 16, if the preset values D or E of the digital preset devices 12 or 13 are selected, the counter reading Xy, and outputs this to the subtracter 18, while if the preset values T? or G of the digital presetting devices 14 or 15 are selected, it selects the counter reading X ^ of the counter 10 and sends it to the subtracter 18, and repeats the previously described effect. The subtracter subtracts the preset value of the digital presetting devices 12-15 from the count of the counter 7 or 10, whereby it is synchronized with the timing signal. Specifically, the subtracter 18 sequentially performs the subtractions of four types including Z _x , -I), X „-E, Z ₀ -F and X ₀ -G while being synchronized with the timing signal. The order of subtraction of these four types is not no tv: ultimately limited to that given above. A circuit 19 judges the subtraction result as to whether it is plus or minus and is similarly synchronized with the timing signal TM. A demultiplexer 20 and locking circuits 21 to 24 are also provided. The demultiplexer 20 switches the respectively ascertained results of the subtractions of the four types, which have been judged by the judging circuit 19, to the respective latching circuits corresponding to them. Therefore, if the subcractor performs the calculation of X ^ -D and it has been determined that the result is plus or minus, that is judged

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Result held by the latch circuit 21. Thereafter, the subtracter 18 performs the calculation XE, and the result is judged whether it is plus or minus and held by the latch circuit 22. In the same way, the result of the calculation XpS with regard to plus or minus is held by the latch _{circuit 23, while the judged result of the computation of X 2} -G, plus or minus, is held by the latch circuit 24-, respectively. This Ve Interlock circuits 21 to 24- output an "Ö" if the evaluated result is plus and output a "1" if the evaluated result is minus. If the evaluated results change, the corresponding output signals also change HICHT gate 25 reverses an output signal of the latch circuit and a UHD gate 26 receives an output signal from the UICHT gate 25 and an output signal from the switch S and emits an output signal when the time during which the plunger passes through the preset point P ^, is shorter than the lower limit value D. A blocking gate 27 emits an output signal when the switch S. emits no output signal and the interlock Elimination circuit 22 outputs a "1", as well as if the time during which the plunger runs through the preset point P ^ is longer than the upper limit value E. and a TJHD element 29 receives an output signal from the ITICHT element 28 and an output signal from the switch S ₂ and emits an output signal when the time during which the plunger passes through the preset point P _{2 is} shorter is than the lower limit Ϊ. An OR gate 31 is connected to a latch circuit 32 for latching an output signal from the OR gate 31 and outputs a molding failure signal V /. A switch 33 can control

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Reset interlocking circuit 32. This switch 33 may be a manual switch or a timer switch to control the injection molding machine so that a molding failure signal is only given by the interlock circuit 32 during a molding cycle when an abnormal condition occurs. The operation of this circuit will now be explained. First, the upper and lower limit values D, E, i ¹ , G for the preset points P _x 1, P ^ are each preset with the aid of the digital presetting devices 12 to 15 and then the injection molding machine is put into operation. At the start of injection molding by the plunger, the switch Sq is closed and pulses are fed to the counters 7 and 10 via the locking gates 6, 9. Upon receipt of timer signals, the multiplexers 16, 17, the demultiplexer 20, the subtracter 18 and the plus-minus assessment circuit 19 carry out the subsequent effects which the reading of the counter readings X _x , or X _{2 of} the counters 7 or 10, reading out the preset W _e rte of digital VoreinStelleinrichtungen 12-15, subtraction, plus-minus Baur division and the summary of the judged results to the associated latch circuits 21 to ■ 2 '+ include. This read-out described for summarizing is repeated to count the pulses as a continuation of the increase in the counter readings X _x ] and X ₂ with the passage of time. Since the switch S ^ is open (Sp is usually also open). Until the plunger passes through the preceding point P _x , the ULTD elements 26, 19 do not emit any output signals. If, in addition, the casting is carried out normally, the counter reading X _x , does not exceed the upper limit value E, which is preset for P ,, before the ram passes through _{the preset point P x.} The latch circuit 22 therefore outputs a "0" output signal. The interlocking circuit 24 also emits an output signal from "0". the

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Λ 4

Blocking gates 27, 30 therefore do not emit any output signals. If the plunger passes the point P> i ·> s °, the switch S ^ is closed. As a result, the blocking gate 6 is closed and the counting process is interrupted by the counter 7 and the counter status is displayed on the display 8. If at this point X ^, is greater than the lower limit value D, an output signal "1" of the latch circuit 21 is reversed by the UICIED element. Therefore, even if the switch S is closed, the AND gate 26 does not emit an output signal. In this case, if X ^ is less than the upper limit value E-, the "latch circuit 22" outputs an output signal "0" and the blocking gate 27 does not emit an output signal passes through, X ^ is, if H ^ remains within the range of D ^ X .. ^ E, the UHD gate 26 and the lock gate 27 therefore give no output signal. In contrast to this, the latch circuit 21 gives an output signal "0" which is reversed by the ITICHT gate if D> X ^. The AND gate 26- therefore emits an output signal which actuates the latch circuit 32 to emit a casting error signal ¥ ^ is not reached and stops shortly before this, the interlocking circuit emits an output signal "1" and in the same way a casting error signal V. In the lall in which the plunger passes through the point P ^ and then the point P ₂ runs through when the time during which the plunger de n passes through point P ₂ , X is ₂₂ , a casting error signal W is not transmitted as long as Ii ¹ ^ X ₂₂ = & . If E " ⁷ Xp ₂ or ^X 22 ^{> G)} S ^{just the} UHD element 29 or blocking gate 30 from an output signal in order to actuate the locking circuit 32 in order to emit a casting error signal W. As described above, according to the invention a casting error Signal W given when the respective times during which the plunger reaches the preset points P ^ ,, P _2, respectively

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runs through, do not lie within the ranges between the upper and lower limit values, which are each given by the preset values P _x ., P _p . This signal can therefore actuate an alarm or an electromagnet of a firing device for sorting out defective castings. In the case where the relationship between the travel of the ram and the time is the same as that of the graph shown in Fig. 7A, a molding failure signal W is not output. In the case of FIGS. 7B, 7C or ^ E , a casting error signal W is emitted. In the present exemplary embodiment, the times during which _{the slide passes through the points P x} 1, Pp are indicated by the indicators 8, 11, respectively. The display can therefore be used to judge the quality of the defective castings or the quality of the good castings. In addition, the upper and lower limit values can be selected as desired by the digital presetting devices 12 to 15.

Fig. 9 shows a circuit for measuring the temperature at a certain point of the Porm within the molding cycle. This circuit is used together with the circuit shown in Fig. 8, for example, so that the judgment of defective molding can be carried out more reliably. In 9, the gate shape 34 is provided with a hole 4-7 partially penetrating it, next to a space 46. A thermal resistor 4-8, like a thermistor, is arranged in the bottom of the hole 47. A resistor-voltage converter 4-9 forms converts the resistance value of the temperature measuring resistor 48 into a voltage which is applied to and held by a sample and hold circuit 50. This sample and hold circuit 50 holds a voltage supplied to it by the resistance-voltage converter 49 and receives it a timer pulse T _x , from a timer

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generator 51 · The voltage value held by the sampling and cooling circuit 50 through the timer pulse T1 from the timer generator 51 is converted by a voltage frequency converter 52 into a pulse sequence, the number of which corresponds to the voltage value from the voltage-frequency converter 52 to a counter 54 via a "logic element 53, which is opened according to the pulse width of a timer pulse T ^ which is emitted by the timer generator 51". The counter 54- is reset by a timer pulse T-, from the timer generator 51, immediately before the logic element 53 is opened by the timer pulse T ^. A pulse fed to the counter 54- via the logic element 53 is after the resetting of the counter 54- counted by the timer pulse T ^ and the counter was indicated by a display 55 digitally. The timer generator 51 repeatedly outputs the timer pulses Ty,, . Hur if a pulse signal Tg from an Im Τ-? away. Only when a pulse signal generator 56, which will be described in more detail later, is obtained, the timer generator 51 outputs Ty., ^ 2 »^ only once and then a start pulse T ₁ , once for a comparator, which will be described later. Sq is the aforementioned limit switch which is arranged in a position Pq to emit a signal when the ram starts moving from the injection molding start position. This limit switch Sq can be arranged at a point shown in the drawing, for example by dashed lines, so that the switch can send a signal when the plunger passes through a point a certain distance before the injection molding start position. It can be selected in a desired manner at which point in the casting cycle the limit switch S _Q emits a signal. A signal from the switch Sq is given to the pulse generator circuit 56 which has a differentiating

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circuit and has a monostable multivibrator, this is converted into a pulse signal Tg and emitted via a manually operable switch 57 to the timer generator 51. Digital presetting devices 58 and 59 set the upper and lower limit values of the standard temperature and each indicate 2.B. a digital selector switch. Comparators 60 and 61 compare the digital values with regard to their size. The comparator compares the upper limit value of the standard temperature, which is preset by the digital preset device 58, with the counter reading of the counter 54- upon receipt of a timing pulse T ^ from the timer generator 51 and emits a temperature error signal when the counter reading of the counter 5 ^ - is greater than the upper limit value set by the digital preset device 58. In addition, the comparator 61 compares the count of the counter 5 ^ - ni with the lower limit value, which is preset by the digital Yoreinstelleinrichtung 59, upon receipt of a timing pulse T ^ and emits a temperature error signal when the count of the counter 5 ^ZJ - is less than is the lower limit value which is preset by the digital Yoro adjustment device 59. A temperature error signal emitted by the comparator 60 or 61 is sent to the locking circuit via an OR gate 62 and held there. A switch 54 similar to switch 35 is used to reset the locking circuit 63.

The operation of the present invention will now be explained. The temperature of the mold 34-1 the during of the casting cycle is changeable, is continuously detected by the temperature measuring resistor 4-8. Of the so detected value is converted into a voltage by the resistance-voltage converter 59 and then by the sample and hold circuit 50 held. The from

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the voltage held by the sample and hold circuit 50, which corresponds to the mold temperature is made with the voltage-frequency converter 52 converted into a pulse train and via the logic element 53 for their counting to the Counter 54 · given. The count of the counter 54- is indicated by the display 55. Therefore, if the switch 57 is open, the mold temperature, which is related to the Casting cycle changes, recorded and digitally with the help of the temperature measuring resistor 4-8 and the display 55 are displayed. To detect a temperature error of the form Fourth must be preset in the digital gate setting devices 58,59 and the switch closed will. When the plasticization of a synthetic resin material is finished, the plunger 4-2 with the help of the hydraulic Pressure in the cylinder 44- advanced in the direction of the arrow in the injection molding start position and the ring 4-5 on the plunger 4-2 actuates the limit switch Sq, whereby this emits a signal. This signal causes the pulse generator 56 to generate a pulse Tg. If this Pulse signal Tg is given to the timer circuit 51, outputs these timing pulses T 1, T2, T ^ and T ^ once each away. The sample and hold circuit 50 therefore holds a temperature signal at the time of the start of injection molding to the time of a subsequent start of injection molding and accordingly hold the counter 54 - and show the display 55 the temperature until the time of a subsequent start of injection molding. In addition, the matcher compares 60 the count of the counter 54- with that by the digital Presetting device 58 preset value using of the timing pulse T ^, and does not emit an output signal, when the count of the counter 54- is lower and gives an output signal when the count of counter 54- is greater than the preset upper limit value, as a result of which it is emitted in tempera for an error signal. To-

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In addition, the comparator 61 compares the count of the counter 54- with the lower limit value of the mold temperature with the aid of the timing signal ¹ H ₁ , which is preset by the digital presetting device 59, and does not emit an output signal if the count of the counter 54- is greater, and outputs a temperature error signal when the count of counter 54- is less than the lower limit value. If either the comparator 60 or 61 emit a temperature error signal, this signal is sent via an OR gate 62 to a latching circuit 63 and held therein. The temperature error signal held in the latch circuit 63 is also output to the outside and used as a signal for operating an alarm or the like. eg used. If the switch 57 is kept open, according to the invention the mold temperature, which changes from time to time during the casting cycle, is digitally displayed by the display 55. In addition, if the switch 57 is kept closed and the upper and lower limit values of the mold temperature at the time of the start of injection molding are preset by the digital presetting devices 58 and 59, the shape value η at the time of the start of injection molding is displayed during the respective injection cycle . At the same time, a comparison is made between the mold temperature at the time the injection molding bag starts in each injection molding cycle and the upper and lower limit values which are preset by the digital presetting devices 58 and 59, and a temperature error signal is output if the mold temperature measured at the time the injection molding start is not within of the range between the upper and lower limit values. If, in addition, the limit switch S _{Q is arranged} at a new point a certain distance in front of the point Pq and the upper and lower limit values are preset accordingly, the form is then

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temperature at the new point is displayed and a detection is made whether or not the mold temperature is faulty at the new point. As previously described, can the point at which the defect temperature is detected in the molding cycle can be chosen as desired and also to be chosen on two or more points. As a signal given to the pulse generator 56, the signal to the Time of opening the mold 36 can be used. aside from that it is possible to use a thermal cell to measure the mold temperature.

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grip ropes

Claims (8)

PATENTANWÄLTE A. GRUNECK = R H. KINKELDEY W. STOCKMAIR / OR-ING Ae = ICALTECH) K. SCHUMANN _m DR BER NA Γ ■ ÖPt_ FHt% P. H. JAKOB ^01ΡΙ - ^1Να G. BEZOLD DRRiRNAT-DIPL-CHEM. 8 MUNICH 22 MAXIMILIANSTRASSE 43 Claims (1.JErfassungseinrichtung for casting defect in a plastic -Sprit zgußmaschine with a metal mold, is introduced to the plastic, and one forwards and backwards movable \ ■ cash plunger characterized by a first Meßeinrich in a part connected to the form cylinder%. ^% The selected point (P ^) passes through a device (12) for presetting the upper limit value; the time allowance for this first point is passed through a device (13) for presetting the lower limit value of the time allowance for this first point by a device (52) for emitting a casting error signal when the time measured by the first measuring device (5,6,7,16,17,18) deviates from the time allowance between the upper and lower limit values, by a second measuring device (5,9,10,16,17,18) for measuring the time during which the S. The plunger (42) passes through a second point (Pg) that differs from the first and is preset in the injection molding stroke of the plunger (42), by means of a device (14) for placing the upper limit value of the time allowance for the second point (j? o )> 809881/0660 TELEPHONE (Ο8β) 22 3883 TELEX OB-29 3BO TELEGRAMS MONAPAT TELEKOP1ERER ORiGINAL INSPECTED by means (15) for setting the lower limit of the time admissibility for the second point (P ₉ ) and by means (32) for emitting a casting error signal when that of the second measuring device (5,9,10,15 , 17,13) deviates from the time allowance between the upper and lower limit values. 2. Detection device according to Angruch 1, characterized in that the measurements of the times during which the plunger (4-2) passes through the first and second points (P,., Pp) are started at the same time when the plunger (4-2) leaves the injection molding starting parts (P _Q). J. Detection device according to claim 1, characterized in that the measurements of the times during which the plunger (42) the first and second points (P,., P-,) passes through, are started when the The plunger (4-2) passes through a point that has a certain Distance from the injection molding start point (P-O is advanced. 4-, detection device according to one of claims 1 to 3, characterized in that the first and second heaters (5,6,7,9,10,16,17,18) respectively Counter circuits (7,10) on v / iron and that the devices (12,13,14-, 15) for Voreins share the upper and lower limit values for the first and second points (P / i j P) each have digital switches. 5- detection device according to one of claims 1 to 4-, characterized in that display devices (8,11) for displaying the times measured by the first and second measuring devices (5,6 ... 17,18) are provided in each case. 809881/0660 6. Erfassun gseinrichtung according to one of claims 1 up to 5s marked by a device (48 to 54) for sensing the mold temperature at a desired point within the casting cycle, by means (58) for presetting the upper limit value for the mold temperature, by means (59) to preset the lower limit value the mold temperature and by means (63) for outputting a temperature error signal when the mold temperature deviates from the range between the upper and lower limit values. 7. Detection device according to claim 6, characterized in that the device (48 to 54) to detect the mold temperature outputs the temperature as a digital value while the facilities (58,59) each have a digital presetting device for presetting the upper and lower limit values. 8. Detection device according to claim 7> thereby g e indicates that means (55) for digitally displaying the by the detection means (48 to 54-) temperature recorded for the mold temperature is provided. 808881/0660