JPS61169220A - Detecting device of operational defectiveness in resin injection molder - Google Patents

Abstract

PURPOSE:To detect a defective molded part due to the generation of short short through the non-arrival of molding pressure to the predetermined reference pressure and consequently prevent defective molding from occurring again in the following molding cycle by a structure wherein molding pressure detectors, pressure setting parts, comparing parts and a time counting part are provided. CONSTITUTION:Firstly, when injection is started, the count-clear signal of the counting part of a time circuit 45 is released, resulting in bringing the counting part into starting the couting by the counting part. If the levels of the outputs of the respective comparators in comparing parts 20 and 21, to which the signal issued from a molding pressure detector 13 is inputted, do not rise to the levels of reference pressure set in advance, a time counting part 40 outputs a lapse signal after the predetermined period of time, resulting in causing the output of a descriminator 51 to go to the 'H' reference level, lightening an alarm lamp and outputting the instruction for opening a molding die. Now, when all the detecting parts of molding pressure detectors detect the pressures exceeding the respective reference pressures, the shifting of process from the injection process to the following process is performed, resulting in preventing defective molding from occurring.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention detects the molding pressure exerted on the cavity surface of the mold by the molten resin injected into the cavity of the mold of a resin injection molding machine. The present invention relates to a malfunction detection device for a resin injection molding machine that outputs a signal indicating a defective molded product when the molding pressure does not reach a predetermined pressure by the time the injection ends, thereby preventing continuous molding with defective molded products.

[Prior art] During resin injection molding, there is an injection process from when molten resin is injected into a mold cavity until it is smoothly filled with a predetermined molten resin, and a pressurization process that follows from the injection process. Let's think about the process of transitioning to .

Conventionally, the injection process has been controlled based on time or injection intervals. Specifically, there is a method in which the injection cylinder automatically moves to the next pressurizing process 8 seconds after it first moves forward, or a method in which the injection cylinder moves forward by a predetermined stroke length to move to the next process. The injection process was controlled using the following method. However, for example,
Variations in the viscosity of the molten resin, variations in the mold temperature, variations in the extrusion speed, and other conditions such as the solidification of the resin ('l) may cause the bending part of the mold, etc. In many cases, the molding pressure rises to a predetermined standard pressure and the molten resin does not flow properly, causing the bent parts of the product to be molded in a defective state.Furthermore, once a molding defect occurs, , molding defects often occur continuously at the same location, resulting in material loss and production ↑11.

In addition, the so-called above-mentioned Show 1 was not noticed until the mold was cooled down after injection, the mold was then opened, and the molded product was taken out. Therefore, a period of time was required for cooling, and production efficiency was also poor.

[Problems to be Solved by the Invention] Therefore, the present invention detects the pressure exerted by the molten resin on the cavity surface, particularly the pressure at the bent portion, as an actual phenomenon within the cavity. However, when the pressure does not reach a predetermined pressure, the purpose is to prevent the transition from the injection process to the next process and quickly detect defects, thereby improving the performance of the resin injection molding machine. .

[Means for Solving the Problems] The present invention provides at least one molding pressure sensor which is disposed on the cavity surface of a molding die and which detects the molding pressure received from the molten resin injected into the cavity. a detector; a pressure setting unit that sets a reference pressure; and a pressure setting unit that starts measuring time from the time when injection of the molten resin into the cavity is started, and when a predetermined time has elapsed, generates an elapsed signal indicating the elapse of time. at least one comparison section that inputs signals from the molding pressure detector and the pressure setting section and outputs a determination signal indicating that the molding pressure has become larger than a reference pressure. and a logic circuit that inputs signals from the timer section and the comparison section and outputs an alarm signal when the judgment signal is not input within a predetermined time. It is a device.

The molding pressure detector is a detector that detects the pressure received from the molten resin injected into the cavity of the molding die, and outputs a signal in accordance with the pressure. As the pressure sensor, for example, a piezoelectric element that outputs an electrical signal in response to the pressure is desirable.

The concepts of the reference pressure, comparison section, and time measurement section will be explained below using FIG. 1. In FIG. 1, the horizontal axis shows the passage of time after injection of the molten resin into the cavity is started, and the vertical axis shows the molding pressure P that the cavity surface receives from the molten resin. The reference pressure is a critical pressure at which the bent portion of the molded product will be defective if the pressure does not exceed this pressure during injection, and is the value of P2 in the figure. That is, if the molding pressure P does not reach the reference pressure P2 by the time injection is completed, there is a high possibility that the product will be defective, especially at the bent portion.

The 81 hour section measures time from the time when the above-mentioned indexing is started.
5 - This is a device that outputs a progress signal when a predetermined time has elapsed, that is, after a time corresponding to a set injection time has elapsed. In the figure, the progress signal is output at time T=T10.

The comparison section inputs signals from the molding pressure detector and the pressure setting section, and determines that the molding pressure P is the reference pressure (P2).
This is a device that outputs a determination signal indicating that the

The logic circuit can be constituted by an AND circuit or an AND element, etc., which inputs signals from the time measurement section and the comparison section and determines whether a condition is met.

A digital comparator, a microcomputer, etc. can be used as the main circuit components of the comparison section, the time measurement section, and the logic circuit.

The molding pressure detector receives pressure from the molten resin injected into the cavity of the molding die, and outputs a signal corresponding to the pressure that changes every moment according to the injection to the comparison section. The pressure setting section outputs the reference pressure set before the start of the molding cycle to the comparison section.

The timing section starts timing when the injection starts, and -〇
- Output a progress signal when a predetermined time has elapsed.

The logic circuit receives signals from the H1 time section and the comparison section, and outputs an alarm signal when the progress signal is input and the judgment signal is input.

[Example] Hereinafter, the present invention will be explained in detail based on specific examples.

FIG. 2 is a block diagram of a malfunction detection device for a resin injection molding machine according to a specific embodiment of the present invention, and FIG.
It is a more specific block diagram of the figure.

The apparatus of this embodiment will be explained below using FIGS. 2 and 3.

In the following explanation, the flip-flop circuit, the logical sum circuit, the logical product circuit, the transistor, the comparator, and the inverter element are respectively referred to as "", 0RXAND, TR,
It is abbreviated as COMP and INV. Regarding signal terminals, the input terminal and output terminal are IN and OUT, respectively, and the signal level is high level and low level, respectively.
Abbreviated as n and L.

The molding pressure detector includes a first pressure detector 10111 and a second pressure detector 10111.
It consists of a piezoelectric element 13, whose output terminal electrical resistance changes depending on the molding pressure received from the molten resin, and an amplifier 17 that processes the detected signal. .18 etc. The piezoelectric element 13.15
are the bent portions 300 . of the lower mold 7 shown in FIG. 4 , respectively.
400. FIG. 5 is a detailed view of the piezoelectric element 13 disposed in the bent portion 300. A cavity 301 is provided in the lower mold 7, a piezoelectric element 302 is housed therein, and a protrusion 3 is provided in the lower mold 7.
A push pin 304 having a pressure of 0.03 applies pressure from the molten resin 306 to the piezoelectric element 302. The piezoelectric element 15 is also arranged in the same manner as the piezoelectric element 13.

Specifically, as shown in FIG. 3 (a), the detection section 130 of the pressure detector 10 is constituted by a bridge circuit consisting of resistors 1 31 to 133, the piezoelectric element 13, and an electric conductor 135. This method utilizes the fact that the potential difference between the terminals 136 and 137 of the detection section 30 changes in accordance with an increase or decrease in the resistance of the piezoelectric element 13.

The amplifier 17 is composed of GOMPs 171 and 172, as shown in a specific amplifier circuit diagram 170, and includes the detection section 130.
A differential amplifier circuit 173 differentially amplifies signals from terminals 136 and 137 of the differential amplifier circuit, and an amplifier circuit 177I further amplifies signals from the differential amplifier circuit. Regarding the amplifier 18,
The configuration and operation are similar to the amplifier 17 described above.

Pressure setting sections 30.31 for setting reference pressure horns are COM 231 and C0M of comparison sections 20.21, respectively, which will be described later.
This is achieved by generating a reference voltage of 241.

The comparators 20.21 each include a comparator 23.24 and a signal holding circuit 2 that holds the signals from the comparator 23.24.
6.27, specifically as a comparator, COMP
231.241, FF261.27 as a signal holding circuit
Consists of 1.

The timing unit 40 includes an injection start signal detector unit 41 that detects the start and end of injection, an injection completion signal detector 4-9=3, a timer circuit 45 that measures time, and the timer circuit 4.
The signal holding circuit 47 holds the signal from 5. Specifically, as shown in FIG. 3(b), the injection start signal detector 41 has a contact point 411 that inputs the injection start signal.
, TR412, and INV413, and the injection completion signal detector 43 has a contact/1 to which the injection completion signal is input.
31, TR432, INV433.434, OR435
The timer circuit 45 consists of a setting section 453 and a timer 451, and the signal holding circuit 47 as a whole consists of a =L
rF F wo formation 1 ru I NV471.472, AND4
73.474.

The logic circuit is composed of a discriminator 51, and as shown in FIG. 5(b), INV511.512, AND513 to 516.
It consists of 0R517 and 518.

In addition, the reset section 42 that is reset when the alarm signal is output is set to the reset button 421, TR422, INV4.
23.0R424F configuration.

An output circuit 53 driven by the device of the present invention is provided.

The output circuit 53 outputs, in response to the signal from the discriminator 51, a circuit consisting of a TR 533 that lights up an alarm lamp and a relay 536, and a mold open (stops its cycle erosion) signal for the resin injection mold. INV531,532,T
It consists of a circuit consisting of R534 and relay 536.

Considering the signal flow of the detector 130 of the molding pressure detector, the resistance value of the piezoelectric element 13 of the detector 130 changes depending on the pressure received from the molten resin. Therefore, the potential at terminals 136, 137 of detector 130 changes. Amplification circuit 170
amplifies the signals input from the terminals 13G and 137,
It is output to COMP231 of the comparator 23. Said C0M2
31 inputs the signal from the amplifier circuit 170 and the pressure setting section 30, and when the signal from the amplifier circuit 170 is smaller than the signal from the pressure setting section 30, 0tJT23.
The 3d level is 1-. The above operation is performed by the detector 150
The same goes for the flow.

The process in which the molding pressure and the reference pressure are compared and processed will be described below using the time chart shown in FIG. Figure 6 shows
The horizontal axis shows the passage of time, and the vertical axis shows changes in the signal level of the output terminal of the device shown by 7'J to (j) in FIG. The above (a> to (j)) are respectively the start detection section 41, the ff4 o'clock section 45, the comparison section 23, the same 24, the signal holding circuit 26, the same 27, the discriminator 51, the alarm lamp relay 53G, and the mold opening. The level states of the respective output terminals of the relay 535 and the reset circuit 42 are shown.

Broken lines 500 and 501 indicate the molding pressure horn detector 10, respectively.
．． 11 shows a reference pressure (P2) level compared to 11.

When injection is started at time T=T1, 0UT415 of TNV/113 becomes ]- (FIG. 4(a)).

In other words, the count clear signal of the timer 450 force count unit 451 is released and the time starts at 81:00 ((b) in the same figure, the comparator unit 20 inputting the signal from the molding pressure detector 13.15
, 21 each COMP231.24117)OU
The pressure does not rise to the standard pressure P2, which is expressed by L/be/shi l, t, and rupture Fi + 500.501 ((C) and (d) in the same figure).
). Therefore, the level of 0tJT263.273 of [F261, 271 in the comparison section is 1 (see figure (e)
), (f)).

The timer 40 outputs a elapsed signal (1-Level) after a predetermined time t1 ((b) in the same figure), and the discriminator 51 outputs a 0uT519.
The level becomes 1 ((g) in the same figure), and a command to turn on the warning lamp and open the mold is output ((1) in (h) in the same figure).
). At time T=T5, an operator adjusts the mold to remove defective molding, and presses button 4 of the reset circuit 42.
When 21 is pressed (J) in the same figure), the alarm lamp turns off,
The command signal changes to the cycle return command signal ((h), () in the same figure).
1)), the holding circuit 47 also returns. The next injection process starts from T10. In this case, the molding pressure of the bent portion 300 detected at COMP23 is the reference pressure P2.
However, the molding pressure of the bent portion 400 exceeds the reference pressure P.
2 is not reached, the logic circuit 51 outputs a control signal to stop the alarm cycle. In other words, when all the detection parts of the molding pressure detector reach their respective quasi-N pressures or higher, the injection process moves to the next process.

-13 According to this embodiment, the injection process can be managed according to the pressure state within the cavity by providing a molding pressure detector, a pressure setting section, a comparison section, and a timekeeping section.

When the molding pressure in the cavity does not rise to the standard pressure, no cooling time is provided, the warning lamp is turned on, the cycle is automatically stopped, the mold is opened, etc., and the monthly profit is reduced without continuously producing defective molding. loss of time and money can be prevented.

In addition, in this example, molding pressure detectors were arranged at two locations and the reference pressure was set to the same value, but a plurality of detectors were arranged and the reference pressure was set according to each bending part. This allows for fine-grained control.

[Effects of the Invention] According to the present invention, by providing the molding pressure detector, the pressure setting section, the comparison section, and the time measurement section, the injection process can be managed according to the actual molding pressure in the cavity. When the molding pressure does not reach a predetermined standard, it can be detected that a defective product has been formed due to the occurrence of a short shot, and the next molding defect can be prevented, waste of molten resin can be prevented, and the resin index molding machine can be Performance can be improved.

[Brief explanation of drawings]

FIG. 1 is a pressure one-hour characteristic diagram showing the pressure inside the cavity of a molding die used to explain the configuration of the apparatus of the present invention. 2 and 3 are a block diagram and an electric circuit diagram, respectively, of a specific embodiment according to the present invention. 4 and 5 are explanatory diagrams of the sensor section of the molding pressure detector used in the same embodiment, and FIG. 6 is a time chart showing the operation of the same embodiment. 10.11... Molding pressure detector 13.15... Pressure N element 20... Comparison section 30.
...Reference pressure setting section 40...Timekeeping section 51...Discriminator patent applicant Kuruda Gosei Co., Ltd. agent Patent attorney Hirodo Okawa Patent attorney Shudo Fujitani Patent attorney Akio Maruyama Figure 1 □ Time

Claims (1)

[Scope of Claims] At least one molding pressure detector disposed on a cavity surface of a molding die to detect molding pressure received from molten resin injected into the cavity, and a pressure setting for setting a reference pressure. a timing section that starts timing from the time when injection of the molten resin into the cavity starts, and outputs a elapsed signal indicating the elapse of time when a predetermined time has elapsed; and the molding pressure detector. , at least one comparison section that inputs a signal from the pressure setting section and outputs a determination signal indicating that the molding pressure has become larger than a reference pressure; A malfunction detection device for a resin injection molding machine, comprising: a logic circuit that outputs an alarm signal when the determination signal is not input within a predetermined time.