JP2002160263A - Flow velocity vector sensor, fluid monitor using the same, and resin molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow velocity vector sensor suitable for observing the flow state of a resin in a mold when the resin is to be molded in the mold. SOLUTION: The flow velocity vector sensor is equipped with a sensor holding member 1, at least two sensors 6 fixed and held to the end surface of the holding member and a connection means for connecting the sensors and a measuring instrument.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow velocity vector sensor for measuring a flow state of a fluid having heat and a monitor using the same, and more particularly to a flow rate sensor for molding a resin in a mold. The present invention relates to a flow velocity vector sensor suitable for observing the flow state of a resin in a mold, a fluid monitor apparatus for detecting a molding defect in a mold using the sensor, and a resin molding method capable of preventing a molding defect. It is.

[0002]

2. Description of the Related Art A flow rate and a flow direction of a fluid have been measured using a pressure sensor, a temperature sensor, and the like provided in a flow path of the moving fluid. A satisfactory flow velocity vector sensor capable of directly detecting a vector has not been developed so far.

On the other hand, complicated flow behavior occurs in a mold having a three-dimensional shape in injection molding, and various failure phenomena are more likely to occur than in a two-dimensional shape.
It is very important to know the flow phenomenon of the resin in the mold. In particular, typical molding defects due to the flow phenomenon in the mold include weld lines, shorts (unfilled),
Flow marks, sink marks, warpage, and the like. These failure phenomena are caused by various individual generation factors such as materials, molds, molding conditions and the like, but can be generally classified into reproducible failure phenomena and sudden failure phenomena. Among them, there is a failure phenomenon due to long-term condition fluctuation gradually generated due to subtle condition fluctuation such as molding machine and mold temperature in a long molding process.

[0004] The causes of such sudden molding failures and failure phenomena due to long-term fluctuations in conditions include the fact that the flow pattern in the mold deviates from the case of molding non-defective products,
Alternatively, as a result, the deviation may occur. In addition, product design and materials,
Although drastic measures are taken, such as changing the mold and molding conditions, unexpected failure phenomena are less likely to occur in general molding processes such as irregularities in materials and malfunctions due to unexpected causes of molding machines. There is molding failure. With respect to the above-mentioned molding failure, it is necessary to take measures such as monitoring the flow state during molding and controlling the molding conditions.

[0005]

Therefore, as a method of monitoring the flow state in the mold, a pressure sensor previously installed in a part of the mold cavity, a load cell for measuring a change in load on a screw of an injection molding machine, and the like are known. Accordingly, a method of monitoring a pressure fluctuation pattern in a pressure-holding and cooling process from a flow process has been mainly used. However, these are not measurements during the resin flow process in the mold,
The main focus was on the measurement during the compression, holding and cooling processes in the mold after the flow, and it was not a method of directly monitoring the flow state. As an effective method for monitoring the flow state, a method of measuring the flow velocity can be considered. Specifically, in order to measure the flow velocity, the pressure (or temperature) at two or more points in the mold is measured using a pressure sensor (or temperature sensor).
Is used to determine the difference in the rise time of the pressure (or temperature), and to determine the average speed between the two measurement points. However, this method increases the size of the sensor,
In addition, since the average velocity at a long flow distance between the measurement points is merely obtained, an accurate flow velocity vector cannot be obtained.

Therefore, the present invention provides a flow velocity vector sensor in which a sensor holding member is disposed at a portion in contact with a moving fluid, and a thermocouple or an optical fiber sensor is incorporated at the tip of the sensor holding member, and the above-mentioned problems are solved. The purpose is to do. In addition, the present invention provides a monitor that can monitor a defective product in a mold by measuring a velocity vector based on a rapid change in thermoelectromotive force caused by resin passage using the sensor, and solve the above problem. Aim. Further, it is another object of the present invention to provide a molding method by which information detected by the sensor is fed back and a molding defect is not generated, and to solve the above problems.

[0007]

For this reason, the technical solution adopted by the present invention is a sensor holding member, at least two or more sensors fixed and held on an end face of the holding member, and a sensor and a measuring instrument. And a connection means for connecting the flow velocity vector sensor to the flow velocity vector sensor. The sensor is a thermocouple or an optical fiber sensor, and is a flow velocity vector sensor. The sensor holding member may be any one of a mold ejector pin, an insert pin with a shank, an insert block, or a mold ejector pin, an insert pin with a shank, and a member having the same shape as the insert block. The flow velocity vector sensor according to claim 1 or 2, wherein:
In addition, any one of the above-described vector sensors, a measuring device that measures a signal from the sensor, a calculating unit that calculates a flow velocity and a flowing direction based on the signal from the measuring device, and a result of the calculating unit as a map in advance. Compare with the data that is embedded,
If the value exceeds a predetermined threshold value, a judgment means for judging a defect is provided, a feedback means for feeding back a signal from the judgment means to the molding machine, and a display means for displaying a signal from the judgment means. A fluid monitoring device characterized by the following. In the resin molding machine, the signal from the vector sensor arranged in the cavity is measured, and based on the measurement result, the flow velocity and the flow direction of the fluid are calculated, and compared with data incorporated in advance as a map,
A resin molding method which exceeds a predetermined threshold value is a resin molding method for preventing molding defects, which is characterized by determining that the molding is defective.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a flow velocity vector sensor according to the present invention will be described below. FIG. 1 is a side view of the flow velocity vector sensor, FIG. 2 is a component diagram of the same, and FIG. It is an arrow view and is an end elevation of the same sensor. 1 to 4, reference numeral 1 denotes a sensor holding member, which has a cylindrical shape in this embodiment, and a sleeve 2 for accommodating a sensor lead wire 3 is integrally or detachably attached to the holding member. Mounted on As shown in FIG. 2, the holding member has a structure in which three grooves 1a are formed at equal intervals around the holding member 1, and a thermocouple as the sensor 6 is housed and fixed in the groove 1a. A groove 2a for accommodating and holding the lead wire 3 is formed in the holding member mounting portion of the sleeve 2. Further, a shank portion 4 having a detent means 4a is attached to the end of the sleeve 2, and the lead wire 3 is connected to a measuring instrument 5 through the shank portion 4 attached to the sleeve 2 as shown in FIG. These components constitute a flow velocity vector sensor S using a sheath-type thermocouple. As shown in FIG. 3, at least two, and preferably three, sensors 6 are arranged at equal intervals at the tip of the sensor holding member 1, and the lead wires 3 are formed in the sleeve 2 or on the outer periphery of the sleeve. Or formed integrally with the sleeve. In addition, the sensor can adopt various forms such as a form housed in a hole formed in the holding member as shown in FIG. 4 or a form in which a groove is formed around the sensor and housed in the groove. As the sensor 6, an optical fiber sensor or the like can be used in addition to the thermocouple.

Note that the sensor holding member 1 does not necessarily have to be cylindrical, and any other shape can be adopted as long as it does not affect the fluid.
Further, as the sensor holding member 1, for example, when measuring a moving fluid in a mold, an ejector pin for a mold, an insert pin with a shank, an insert block, or the like can be used, and the sensor 6 can be embedded therein. However, apart from this, it is also possible to use a member having the same shape as an ejector pin for a mold, an insert pin with a shank, an insert block, and the like, and incorporate the sensor 6 therein and attach it to the mold. is there.

A method for measuring, for example, the flow velocity and the flow direction of the resin filled in the mold cavity using the flow velocity vector sensor S will be described. As shown in FIG. 3, a flow velocity vector sensor S in which three thermocouple sensors 6 are arranged at 120 ° intervals is mounted in a mold cavity (not shown), and resin filling is started. As the resin flows, the temperature of each thermocouple sensor 6 rises. From the rising signal (the signal that the material has passed) at each point, as shown in FIG. 5, the passage times T1, T2, T3 is calculated, and a resin passing speed (flow speed) on the sensor end surface is calculated from a distance and a positional relationship between the sensor positions that are known in advance.

For example, the distance from the center O of the sensor pin to each sensor position is R, and the sensor at the sensor end face is 120
In the case of FIG. 3 installed at intervals of degrees, as shown in FIG. 3, when the flow direction of the flow material (flow angle with the counterclockwise direction being positive in FIG. 3) is a and the flow speed is V, ch1 and ch1 ch
2 rise time difference T21 (= T2-T1), ch
The rise time difference T31 between 1 and ch3 (= T3-T
1), the difference T32 between the rise times of ch2 and ch3 (=
T3−T2) is obtained by the following equations.

(Equation 1) From this, a and V are determined as follows. As for a and V, three sets of a and V are independently obtained by combining two of the above three equations. That is, from T21 and T31, the following equation (2), T2
From 1 and T32, the flow angle a is obtained from the following equation 3 from T31 and T32, and the flow angle a is obtained from the following equation 4 from the following equation. A combination of the flow angle a and the flow velocity V according to any of them may be used, or an arithmetic mean may be used. However, in general, the larger the transit time difference, the higher the accuracy of the data.
The flow angle a and the flow velocity V are obtained from any one of Expressions 2, 3, and 4 and Expression 1 by a combination in which two are selected in descending order of the absolute value of T31 and T32.

(Equation 2)

(Equation 3)

(Equation 4)

FIG. 5 shows an output waveform of the thermocouple after passing through the amplifier, obtained by a measurement experiment based on the above method.
The abscissa represents the elapsed time from the injection start time. From the figure, when the resin passes, the high-temperature resin comes into contact with the sensor, so that a rapid increase in the output is recorded in any of the thermocouples. Also,
In the figure, the angle a between the flow direction of the resin, ch1 and the center of the measurement pin is 23 degrees, and each thermoelectromotive force rises rapidly in the order of ch1, ch2, and ch3 where the resin contacts each sensor ch. It is confirmed that. The timings T1, T2, and T3 of the start point of the rise of the thermoelectromotive force are extracted, and the front speed and the flow direction at the time of passing the sensor are calculated by the above-described equations from the time difference between them and the positional relationship between the sensors. From the start point of the rise of the thermoelectromotive force at each injection rate illustrated in FIG. 5, the fluid front velocity was obtained, and the injection rate was displayed on the horizontal axis. The results are shown in Fig. 6. The same experiment was performed using a visualization mold, and the front passing speed was measured by the same sensor while directly visualizing and observing the situation where the resin passed through the measurement pins. Comparison of the measured value with the measurement is made. Similarly, the angle is calculated, and assuming that the visualization result is a correct value, the error between the front speed and the angle (difference from the visualization result) under each of these conditions is calculated, as shown in FIG. In FIG. 7, the vertical axis indicates the difference between the visualization measurement result and the present sensor with respect to the front speed and the angle. The angle in the figure means the flow angle of the resin with respect to the sensor reference line at the time of measurement. From the results in FIG. 7,
The front speed coincided with an error within 10 mm / s, and the flow direction coincided with an error within about 3 degrees. FIG. 7 shows that the angle has a larger error than the front speed. This is a result of the flow being slightly obstructed by the present sensor having the ejector pin shape, and can be solved by adjusting the end face of the present sensor and the cavity surface so as to have the same height.

As described above, in the present flow velocity vector sensor, the flow velocity and the flow direction of the fluid can be easily measured by the outputs from at least two or more sensors attached to the sensor holding member. In the above example, the flow velocity a and the flow direction V are obtained by using three sensors, but may be obtained by using two sensors. In this case, a sensor is generally installed and used at A (see FIG. 3) at a position farthest (180 degrees away) from ch1 in FIG.
When two sensors are used, neither a nor V can be specified. However, generally, two points, ch1 and A, are pre-arranged upstream and downstream in a direction considered to be substantially along the flow direction in the mold. By doing so, it is possible to monitor the speed fluctuation state of the fluid front at a specific measurement point in the mold from the difference TA1 in the rise time of the measurement signal between ch1 and A. It is possible to prevent molding defects such as detecting molding defects from the fluctuation state of TA1.

Next, a description will be given of an apparatus for monitoring a molding defect occurring at the time of resin molding using the above-mentioned flow velocity vector sensor. FIG. 8 is a block diagram of the monitoring apparatus. In the figure, reference numeral 20 denotes a resin molding machine, the flow velocity vector sensor S described above is attached to a cavity of the resin molding machine 20, and a control means 21A for controlling the molding machine is arranged in the molding machine. ing. In this case, as a sensor holding member constituting the flow velocity vector sensor S, an ejector pin for a mold, an insert pin with a shank, or an insert block may be used as it is, or an ejector pin for a mold, an insert pin with a shank, or the like. Use a member made in the same shape as the insert block. The control means 21A
Conventionally, a computer, a control circuit, and the like mounted on a molding machine are used.

In the figure, reference numeral 22 denotes a monitor device. The monitor device 22 is a measuring device 23 for measuring a signal from the flow velocity vector sensor S. Calculating means 24 for calculating the flow velocity and the flow direction by comparing the result of the calculating means with data which has been previously incorporated as a map, and judging means 26 for judging that a value exceeding a predetermined threshold value is defective, A feedback means 27 for feeding back a signal from the means 26 to the control means 21A of the molding machine, a storage means 25 for storing a calculation result, a map, and the like, and an output result from the determination means 26 or the storage means 25 and the feedback means. Display means (for example, a printer, a display, etc.) 28 for displaying is provided. Note that the feedback means 27 can be removed as necessary.

In the above-described apparatus, when a signal indicating a molding failure is output from the judging means 26 based on the output measured from the flow velocity vector sensor S, the operator manually stops the molding machine if necessary, The defective product can be removed, or the control means 21A in the molding machine can be operated to automatically remove the defective product. Further, the output signal from the determination means is fed back to the control means 21A of the molding machine via the feedback means 27, and the filling speed of the resin in the molding machine, the resin temperature, etc. are controlled based on a previously determined map or the like. In addition, occurrence of defective products can be prevented.

In this way, the present monitor device 22 can easily prevent the occurrence of defective molding by removing the defective molding and controlling the molding conditions based on the detection value from the flow velocity vector sensor S. Can be. Further, it can be used for sampling inspection at the time of off-line product inspection after molding, and can also be used as a database for molding process analysis (identification of defect process) for occurrence of complaints of molded article defects after molded article shipment and quality control. The threshold values of defective and non-defective products can be easily set by a database based on empirical values obtained by separately analyzing the values of a or V described above or the values of both under conditions in which molding failure occurs.

Although the embodiments of the present invention have been described above, the configuration of the monitor device can be configured using not only a computer but also a dedicated control circuit. In the above embodiment, the flow rate and the flow direction of the resin to be filled in the mold have been described as an example. However, a fluid other than the resin can be similarly measured. Furthermore, the present invention may be embodied in any other form without departing from the spirit or main characteristics thereof, and thus the above embodiments are merely illustrative in all respects and should not be construed as limiting.

[0019]

As described in detail above, according to the flow velocity vector sensor of the present invention, the flow velocity and the flow direction of the fluid can be easily measured. In addition, it was difficult to detect the poor phenomenon of the flow state of the fluid by the conventional visualization method at the time of resin molding, but according to the present invention, it is difficult to detect the complicated flow behavior occurring in a large actual molded product shape and the like. Analysis can be performed easily, and the flow behavior in the mold to be actually molded can be easily grasped. further,
Based on the output from the flow velocity vector sensor, excellent effects such as monitoring the flow state and controlling molding conditions to prevent occurrence of molding defects in the resin molding machine can be achieved. it can.

[Brief description of the drawings]

FIG. 1 is a side view of a flow velocity vector sensor as an embodiment of the present invention.

FIG. 2 is a component diagram of the vector sensor of FIG. 1;

FIG. 3 is a view taken in the direction of arrow B in FIG. 1, and is an end view of the sensor.

FIG. 4 is a diagram illustrating another example of the end face of the vector sensor.

FIG. 5 is a diagram illustrating a rising state of a temperature in a sensor.

FIG. 6 is a graph showing a flow front speed measured by the present sensor.

FIG. 7 is a diagram showing a difference between a measurement result obtained by the present sensor and a measurement result obtained by visualization.

FIG. 8 is a configuration diagram of a monitor device using the present sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor holding member 2 Sleeve 3 Lead wire 4 Shank part 5 Measuring instrument 6 Sensor 20 Molding machine 21 Cavity 21A Control means 22 Monitoring device 23 Measuring instrument 24 Calculation means 25 Storage means 26 Judgment means 27 Feedback means 28 Display means

Claims (5)

[Claims] 1. A sensor holding member comprising: a sensor holding member; at least two or more sensors fixed and held on an end face of the holding member; and connection means for connecting the sensor to a measuring instrument. Flow velocity vector sensor. 2. The flow velocity vector sensor according to claim 1, wherein the sensor is a thermocouple or an optical fiber sensor. 3. The sensor holding member may be any one of a mold ejector pin, an insert pin with a shank, an insert block, or a mold ejector pin, an insert pin with a shank, and a member having the same shape as the insert block. The flow velocity vector sensor according to claim 1 or 2, wherein the number is one. 4. The vector sensor according to claim 1, a measuring device for measuring a signal from the sensor, and a flow velocity and a flow direction based on the signal from the measuring device. The calculating means for calculating, the result of the calculating means is compared with data which is incorporated in advance as a map, and if the result exceeds a predetermined threshold value, the judgment means for judging a defect and the signal from the judging means are sent to the molding machine. A fluid monitoring device comprising a feedback unit for feeding back and a display unit for displaying a signal from the determination unit. 5. A resin molding machine, comprising: measuring a signal from the vector sensor according to any one of claims 1 to 3 disposed in a cavity; and measuring a flow of the fluid based on the measurement result. A resin molding method for preventing a molding defect, comprising calculating a speed and a flow direction, comparing the calculated value with data preliminarily incorporated as a map, and determining a value exceeding a predetermined threshold value as a defect.