JPH075867Y2 - Fluid mixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fluid mixing apparatus for mixing two or more kinds of fluids at a predetermined ratio.

[Conventional technology]

For example, when the main agent and the curing agent are mixed in order to obtain a molded product of urethane rubber, the two must be mixed in a prescribed ratio (quantity ratio). This is because if the mixing ratio is not accurate, the molded product cannot have a predetermined hardness or elastic modulus.

In an apparatus that mixes two or more kinds of fluids for such a purpose, it is general that a nozzle having a small diameter is provided in a portion for discharging the fluid in a mixer (mixing agitator).
This is because the diameter of the fluid is reduced to prevent the fluid from dripping, and so to speak, a thread-like ejection is performed to eject the fluid (mixed volume).
This is for accurate control of.

An example of a conventional fluid mixing device is described in Japanese Patent Application Laid-Open No. 48-53351. The device connects fluid circulation paths to the mixer for each fluid type via switching valves, and switches the switching valves to discharge each fluid from the circulation path in a fixed amount and mix it. A small diameter nozzle is also provided at the fluid discharge portion to the mixer.

[Problems to be Solved by the Invention] As described above, in the fluid mixing apparatus having the small nozzle,
The mixing ratio of each fluid set at the beginning is not maintained permanently. The main reason for this is that minute contaminants in the fluid adhere to (trap) in the nozzle, which hinders the normal ejection of the fluid. When contaminants start to adhere to the inside of the nozzle, the amount of fluid discharged through the nozzle to the mixer decreases, and the mixing ratio gradually goes out of the normal range.

However, the conventional fluid mixing device has not been provided with means for immediately or in advance knowing an abnormality in the mixing ratio of fluids. Therefore, the following inconveniences have occurred. A) Unless the abnormality is detected during fluid mixing, it is usually unknown until the process of molding, solidifying or drying the mixed fluid is completed. Fluid consumption and working time are wasted, and it takes a lot of time to remove a defective mixed material. B) As the period during which the discharge nozzle can be operated in the normal range without cleaning or replacement is unpredictable,
It is difficult to make a rational work plan.

The purpose of this invention is not only to immediately detect and notify when the fluid mixing ratio becomes abnormal, but also to notify that the time of the abnormality is approaching, as described in a) and b) above. It is an object of the present invention to provide a fluid mixing device that solves various problems.

[Means for Solving the Problems] A fluid mixing device of the present invention comprises a fluid mixer and a plurality of fluid circulation paths for each fluid type, which are connected to the fluid mixer via switching valves, and switch the switching valves. As a result, in a fluid mixing device that discharges and circulates each circulating fluid into the mixer in a fixed amount, a pressure sensor is provided in one or more fluid circulation paths, and the pressure detected by the sensor during circulation of the fluid and the mixer are Connected to each of the above-mentioned pressure sensors is a calculating means for comparing the pressure during discharge and judging whether or not the difference has changed by a certain value or more, and a notifying means for issuing an alarm signal based on the output of the calculating means. It was provided by.

[Operation] The fluid mixing apparatus of the present invention discharges a plurality of kinds of fluids, which are respectively circulated in the circulation paths for each kind of fluid, into the mixer in a fixed amount by switching the switching valve for a predetermined time.
The mixer mixes and agitates the multiple types of fluid discharged in this way, and then discharges them for injection into the molding machine, spraying / painting on the coating or bonding points, or addition to other solutions. To do.

Since this fluid mixing device has the pressure sensor, the calculating means, and the notifying means as described above for one or more fluids for which it is necessary to strictly control the mixing amount, that is, the discharge amount to the mixer, the fluid mixing device An abnormality in the discharge amount (mixing ratio) due to the clogging of the discharge portion of the discharge sensor is detected and notified as follows. That is, first, the pressure sensor detects the fluid pressure in the circulation path, and outputs the pressure of the fluid being circulated (hereinafter referred to as the circulation pressure) and the pressure being discharged to the mixer (hereinafter referred to as the discharge pressure) to the calculating means. To do.
If the discharge to the mixer begins to become clogged, the discharge pressure of that fluid will begin to change with respect to the circulation pressure.
Receiving such an output from the pressure sensor, the calculating means determines whether or not the difference between the circulation pressure and the discharge pressure has changed by a constant value (reference value) or more from the normal time, and outputs the result to the notifying means. A notification means such as a lamp or a buzzer issues an alarm signal according to the output.

The change in the discharge pressure occurs at the same time as the discharge amount to the mixer is abnormal, and the change is immediately detected and notified by the pressure sensor, the calculation means and the notification means. You can know immediately. Further, if the above-mentioned constant value (reference value), which is the criterion for the abnormality judgment by the calculating means, is set to a slightly smaller value (safety side), the mixing ratio of the fluid is still within the normal range. In addition, it is possible to know that the time to become abnormal is approaching.

It should be noted that the reason why the abnormality of the discharge amount is judged not by the change of the discharge pressure but by the change of the difference between the discharge pressure and the circulating pressure is because the change of the discharge pressure due to the change of the fluid property such as viscosity is excluded. Is. For example, the discharge pressure changes with the change in the viscosity of the fluid even during normal operation without clogging of the discharge part. At this time, the discharge pressure is changed to the circulating pressure that also changes with the change in viscosity. By making a comparison, it is possible to avoid erroneously determining an abnormality.

[Embodiment] FIG. 1 shows a system diagram of a fluid mixing apparatus according to an embodiment of the present invention. This device is used as a base material (prepolymer) for molding urethane rubber using a casting machine (not shown).
And a curing agent (crosslinking agent).

In the figure, reference numeral 1 is a mixer for mixing and stirring the above two kinds of fluids. This mixer has a structure in which a stirring blade (not shown; connected to the shaft 3 inside the mixer 1) is rotated by the power transmitted from the pulley 2 via the shaft. The fluids discharged into the mixer 1 from the circulation paths 10 and 20, which will be described later, are stirred by the stirring blades, discharged from the discharge port 4, and injected into the casting machine.

Reference numerals 10 and 20 are the circulation paths for the above-mentioned curing agent and main agent, respectively. The circulation path 10 includes a fluid (hardening agent) storage tank 13
And the pump 14 etc., but the three-way switching valve 11
Is connected to the discharge line 12 to the mixer 1 via.
Also for the circulation path 20, similarly, the tank 23 and the pump 24
And the switching valve 21 is interposed, and the discharge pipe line 22 to the mixer 1 is provided.
Is also connected to. The two types of fluids normally circulate in the circulation paths 10 and 20, respectively (in the illustrated state),
When the switching valves 11 and 21 are switched, they are discharged into the mixer 1 through the discharge pipe lines 12 and 22 without returning to the tanks 13 and 23. A small-diameter nozzle (not shown) is provided in the discharge portion from the discharge pipe lines 12 and 22 to the mixer 1, and a predetermined amount of discharge can be performed every time by setting the switching time (period) of the switching valves 11 and 21. Is.

In order to satisfy the required physical properties (hardness, elastic modulus, etc.) of the molded product, the mixing ratio (weight ratio) of the curing agent to the main agent should be (7).
Must be ± 0.2)%. In order to discharge the two liquids to the mixer 1 at a ratio equal to this, the diameters of the nozzles are set so that the discharge amount per unit time becomes the above ratio, and the switching valves 11 and 21 are the same. Operate by switching only the time.

The discharge amount of the curing agent needs to be particularly strictly controlled in accordance with the above mixing ratio, and if an abnormality is present, it must be dealt with immediately.Therefore, in this mixing device, in the curing agent circulation path 10 A pressure sensor 15 was provided on the delivery side portion of the pump 14, and a computing means 16 and an informing means 17 were connected to the pressure sensor 15. The pressure sensor 15 is not a simple on-site display type, but a type that outputs the detected pressure as voltage (current or electrostatic capacity may be used). The pressure of the curing agent in the above part is constantly (or regularly) applied. It detects and outputs the circulation pressure (the pressure circulating in the circulation path 10) and the discharge pressure (the pressure when the switching valve 11 is switched and the discharge pipe 12 discharges the mixer 1). The calculating means 16 composed of a microprocessor or the like calculates the difference between the most recently output circulating pressure and the discharge pressure, and judges whether or not this difference has changed by a certain value or more from the difference during normal operation (at the start of operation). And outputs it to the notification means 17. The notifying means 17 mainly has an alarm buzzer, and when receiving the output of the calculating means 16 that the above-mentioned difference has changed by a certain value or more, it gives an alarm to the operator as "abnormal mixing ratio".

FIG. 2 shows the change over time in the curing agent pressure detected by the pressure sensor 15 of the present apparatus. FIG. 2 (a) shows the operation start and FIG. 2 (b) shows the operation after several tens of hours. The pressure at the times t1 to t2 in FIG. 11A and the times tn1 to tn2 in FIG. 9B is the discharge pressure, but the other portions indicate the circulation pressure.

As shown in FIG. 2 (a), at the start of operation, the discharge pressure and the circulation pressure match, and the difference ΔP between the two is zero. this is,
This is because in the present embodiment, the flow passage resistance (valve, orifice, long pipe, etc., not shown) is appropriately provided in the circulation path 10 before the operation is started, and the circulation pressure is adjusted to the discharge pressure. If the discharge pressure and the circulation pressure are made equal, there is no transient period in which the discharge pressure and the discharge amount per unit time change indefinitely immediately after the switching valve 11 is switched. ) Can be controlled more accurately.

However, when several tens of hours have passed from the above, the discharge pressure shows a value considerably higher than the circulation pressure as shown in FIG. This is because the nozzle that discharges the curing agent from the discharge pipe 12 into the mixer 1 is clogged, and it is impossible to discharge an accurate amount. The calculating means 16 and the notifying means 17 display "mixing ratio (discharging amount)"
“Abnormal” means the difference Δ between the discharge pressure and the circulating pressure as shown in the figure.
The amount by which Pn changes from the difference ΔP at the start of operation, that is, | ΔPn−ΔP |, is a constant reference value (preliminary calculation means 16
The value you entered in) is exceeded. In this embodiment, since ΔP = 0, that is, when ΔPn exceeds its reference value, the calculation means 16 outputs “abnormal” and the notification means 17 gives an alarm.

According to the results of a study by the inventors, in which the difference ΔPn between the discharge pressure and the circulation pressure is associated with the property of the molded product, the molded product becomes defective (that is, the mixing ratio is abnormal) when the above change amount | ΔPn -Δ
Since P | was 0.3 kg / cm ² or more, in this embodiment, the above-mentioned reference value (constant value) by which the calculating means 16 determines abnormality is set to 0.3 kg / cm ² . When the nozzle is clogged, the discharge pressure generally increases gradually with each discharge, so if you set the above reference value to a small value, for example, 0.2 kg / cm ² , the molded product will It is possible to know that the discharge amount is not normal before it becomes defective, and it is possible to predict the period during which the operation can be continued and to perform the rational operation by appropriately cleaning and replacing the nozzle.

FIG. 3 shows the change over time in the pressure detected by the pressure sensor 15 when a fluid different from the above is mixed in the same fluid mixing device as in FIG. 1, and FIG. At this time, FIG. 7B is after the operation is continued. Similar to Figure 2,
The pressures at times t1 'to t2' and times tn1 'to tn2' are discharge pressures, and the rest are circulating pressures. As described above, it is ideal that the discharge pressure and the circulation pressure be matched in advance. However, in this case, due to the relationship between the physical properties of the fluid and the discharge amount, when the operation is started as shown in FIG. To the difference ΔP ′ (≠
0) exists.

In Fig. 3 (b) after the operation is continued, compared with Fig. 3 (a), the discharge pressure slightly rises and the circulating pressure decreases as the fluid temperature rises (the viscosity decreases due to the temperature rise). It has changed from ΔP ′ to ΔPn ′. Unlike the case of FIG. 2, ΔPn ′ becomes smaller than ΔP ′, and the discharge pressure itself has changed only slightly from FIG. 2 (a), but from the magnitude of the change amount | ΔPn′−ΔP ′ | Again, it can be seen that the discharge portion to the mixer 1 is clogged.
If it is normal, the discharge pressure should be lowered together with the circulation pressure due to the decrease in viscosity. Therefore, also in this case, the change amount | ΔPn′−ΔP ′ | is a constant amount set in advance in the calculation means 16 (reference value.
When not exceeding 3 kg / cm ² ), the alarm means 17 gives an alarm of "abnormal".

Although one embodiment of the fluid mixing apparatus of the present invention has been introduced above, the present invention can be implemented as follows.

a) Not limited to mixing of two kinds of fluids, three or more kinds of fluids may be mixed.

b) The number of circulation paths provided with a pressure sensor or the like is not limited to one, and may be any circulation path for one or more fluids for which it is necessary to control the mixing amount, that is, the discharge amount to the mixer. For example, in the above-mentioned embodiment, if the mixing amount of the fluid on the circulation path 20 side should be strictly regulated, the circulation path 20 may be provided with a pressure sensor, and the calculation means and the notification means may be connected. .

c) When pressure sensors are provided in two or more fluid circulation paths as in b) above, the calculation means and notification means connected to each pressure sensor should also be used as calculation means and notification means for other fluid circulation paths. Is also possible. In this case, it is desirable to use a lamp or the like to indicate which fluid has an abnormality as the notification means. It should be noted that if, for example, a pen recorder is connected to each pressure sensor and the operator monitors it, the calculation means and the notification means are not necessary, but in that case, the operator always pays attention to the recorded data and himself. It is necessary to judge the abnormality.

d) The present invention is not limited to mixing fluids relating to molding of rubber or plastics, but can be widely implemented as a fluid mixing device for fluids related to painting, adhesion or chemical addition.

[Effect of the Invention] The fluid mixing device of the present invention has the following effects.

1) Immediate notification that the mixing ratio has become abnormal prevents the production of defective products, wasteful consumption of fluid, and meaningless (unproductive) work time.

2) Since it is possible to notify in advance that the time when the mixing ratio becomes abnormal is near, it is possible to perform planned work and improve productivity. For example, if the discharge part (nozzle) to the mixer is cleaned or replaced at the time of operation stop (lunch break or holiday) when the time of occurrence of abnormality is approaching, the actual operation rate of this device becomes 100%.

3) Low cost and easy configuration for the following reasons. That is, the pressure sensor may be attached only to the fluid circulation passages for which mixing amount control is required, and it is not necessary to provide each pressure circulation passage to each fluid circulation passage. Therefore, in many cases, one sensor is sufficient as in the embodiment.

-For the abnormality judgment by the calculation means, the pressure value for each fluid detected by the pressure sensor is determined by a simple discriminant (| ΔPn−ΔP | − ″
-Since it is performed by subtracting based on a fixed value "> 0?), The calculation means may be simple (low capacity).
If the difference (ΔP) between the discharge pressure and the circulation pressure is set to zero at the start of operation as in the example of FIG.
= 0) is not required to be stored and only the latest pressure difference (ΔPn) and the “constant value” need to be subtracted.

[Brief description of drawings]

FIG. 1 is a system diagram of a fluid mixing apparatus as an embodiment of the present invention, FIGS. 2 (a) and 2 (b) and FIGS. 3 (a) and 3 (b).
Indicates the change over time in the fluid pressure detected by the pressure sensor in the device ((a) of each figure is at the start of operation, and (b) is after operation is continued). Note that FIG. 3 shows a case where a fluid different from the case of FIG. 2 is caused to flow. 1 ... Mixer, 10, 20 ... Circulation path, 11, 21 ... Switching valve, 15 ... Pressure sensor, 16 ... Calculation means, 17 ... Notification means.

Claims (1)

[Scope of utility model registration request] 1. A fluid mixer and a plurality of fluid circulation paths for each fluid type, which are connected to the fluid mixer via switching valves, respectively. By switching the switching valves, each circulating fluid is discharged in a fixed amount into the mixer. In a fluid mixing device for mixing by mixing a pressure sensor in one or more fluid circulation paths, the pressure in circulation of the fluid detected by the sensor is compared with the pressure in discharge to the mixer, and the difference is detected. A fluid mixing device characterized in that arithmetic means for deciding whether or not has changed by a certain value or more, and notifying means for issuing an alarm signal based on the output of this arithmetic means are provided by connecting to each of the pressure sensors described above. .