JPS6236510Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for mixing a gas into a liquid such as a plastic liquid component.

In reaction injection molding, in which molded products are produced by colliding and mixing at least two plastic liquid components that react with each other, the purpose of this is to make the foam structure inside the molded product denser, improve physical properties and appearance, and increase product value. , air is mixed into the plastic liquid component in the form of fine bubbles. Conventionally, a liquid pump that circulates the plastic liquid component through the plastic liquid component flow path, a gas mixing device that mixes gas into the plastic liquid component flowing through the flow path, and a gas mixing device that mixes gas into the plastic liquid component flowing through the flow path are used. Although a gas content measuring device is provided to measure the content of gas contained in the device, it has the disadvantage that the configuration is complicated and the operation is complicated.

Furthermore, if the plastic liquid component contains a filler such as glass fiber, the liquid pump will wear out quickly due to the filler, so in the conventional device using the liquid pump, the filler is not included. The drawback was that plastic liquid components could not be used.

The present invention consists of a circulation cylinder that circulates liquid mixed with gas through a liquid flow path having a plurality of switching valves to a stock solution tank, a pressure detection means that measures the pressure inside the circulation cylinder, and position detection means for detecting the piston position of the cylinder for use, the output of the pressure detection means and the output of the position detection means to calculate the gas content in the liquid, and compare the calculated value with a set value. This device consists of a control device for controlling the above-mentioned gas mixing device, and eliminates the above-mentioned drawbacks of the conventional method.It can also be used for plastic liquid components (slurry liquid) containing glass fibers and other fillers, and has a high resistance to It is an object of the present invention to provide a device for mixing gas into liquid, which can improve abrasion resistance, provide a circulation cylinder with a liquid circulation function and a gas content measurement function, and is simple in structure and operation.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and the reference numeral 1 in the figure is a stock solution tank for storing a plastic liquid component (liquid) in a high-pressure reaction molding apparatus. This stock solution tank 1 has both ends 2 of a liquid flow path 2 consisting of piping.
a and 2b are connected, and a stirring blade 4 rotated by a motor 3 is provided inside. The liquid flow path 2 is for circulating the liquid in the stock solution tank 1. And, the stock solution tank 1 is
The first and second switching valves are connected via the first switching valve 5 which is normally open.
It is connected to the α ends of the three-way switching valves 6 and 7, respectively, and the β end of the first three-way switching valve 6 is connected to one end of a circulation cylinder 8 having high wear resistance. Furthermore, the other end of the circulation cylinder 8 is connected to the β end of the second three-way switching valve 7, and a piston 9a that slides within the circulation cylinder 8 is provided at one end of the piston rod 9. . A piston 9b that slides within the actuator 10 is provided at the other end of the piston rod 9, and a hydraulic circuit (not shown) connected to both ends of the actuator 10 causes the piston inside the circulation cylinder 8 to move. 9a is configured to reciprocate from side to side. When the piston 9a moves to the backward movement end (the leftmost position in FIG. 1), the first three-way switching valve 6 is switched in conjunction with the movement, and the first three-way switching valve 6 is At the same time that the end and the β end are connected, the second three-way switching valve 7 is also switched, and the β end and the γ end of the second three-way switching valve 7 are connected. Further, when the piston 9a moves to the forward end (the rightmost position in FIG. 1), the second and third method switching valves 7 are switched in conjunction with this movement, and the second and third method switching valves 7 are switched. At the same time that the α end and the β end are connected, the first three-way switching valve 6 is also switched,
The β end and the γ end are connected to each other. The γ end of the second and third type switching valve 7 is
It is connected to the γ end of the first three-way switching valve 6 and one end of the gas mixing device 12 via the second switching valve 11, and the other end of the gas mixing device 12 is connected to the check valve 13 and the other end of the gas mixing device 12, which is normally open. It is connected to the stock solution tank 1 via a third switching valve 14.

The gas mixing device 12 is connected to a gas check valve 16 via a pipe 15.
6 is connected to a gas solenoid valve 18 via a pipe 17. The gas electromagnetic valve 18 is connected to a gas flow meter 20 via a pipe 19, and the gas flow meter 20 is connected to a throttle valve 22 via a pipe 21. Further, the throttle valve 22 is connected to a gas pressure gauge 24 and a gas pressure control valve 25 via a pipe 23, and the gas pressure control valve 25 is connected to the pipe 22.
6 to a gas supply source 27.

Further, the piston rod 9 is provided with a hook-shaped probe 28, and a rack 28a formed on one side of the probe 28 is provided with a hook-shaped probe 28.
A pinion 29a of an encoder (position detecting means) 29 for measuring the position a is engaged. Further, the circulation cylinder 8 is provided with a pressure sensor (pressure detection means) 30 for detecting internal pressure, and the encoder 29 and pressure sensor 30 are connected to a control device 31. The control device 31 includes a calculation unit 32 that is connected to the encoder 29 and the pressure sensor 30 and calculates the amount of gas contained in the liquid flowing through the liquid flow path 2; A comparison unit 34 that compares the measured value of the gas content with a set value of the gas content stored in the storage unit 33 in advance is connected to the gas electromagnetic valve 18, and when the measured value is smaller than the set value A command unit 35 is provided which causes the gas electromagnetic valve 18 to open when the value is equal to or greater than the value, and causes the gas electromagnetic valve 18 to close when the value is equal to or greater.

Furthermore, a measuring cylinder 36 and a mixing head 37 are connected to the stock solution tank 1, as is well known, and the plastic liquid component supplied from the stock solution tank 1 is sent to the mixing head 37, and other measuring cylinders (not shown) are connected thereto. The plastic liquid component is mixed with other plastic liquid components sent from other companies, and molded products are obtained by the reaction of both liquid components.

Next, the operation of the apparatus configured as described above for mixing gas into liquid will be explained.

First, when circulating the liquid in the liquid flow path 2, when the piston 9a in the circulation cylinder 8 retreats and moves to the leftmost position in FIG. The switching valve 6 is switched to connect the α end and β end of the first three-way switching valve 6, and the second three-way switching valve 7 is switched to communicate with the second three-way switching valve 6.
The β end and the γ end of the three-way switching valve 7 are communicated with each other, and the first, second, and third switching valves 5, 11, and 14 are each opened. Then, when a hydraulic circuit (not shown) is operated to move the piston 9b in the actuator 10 forward to the right in FIG. 1, the piston 9a of the circulation cylinder 8 is moved to the right in conjunction with this. The liquid in the circulation cylinder 8 flows out from the other end of the circulation cylinder 8 into the liquid flow path 2 through the β and γ ends of the second three-way switching valve 7 and the second switching valve 11, and also flows out into the liquid flow path 2. Liquid flows into the circulation cylinder 8 from one end of the circulation cylinder 8 through the α and β ends of the first three-way switching valve 6. Therefore, the liquid in the liquid flow path 2 is distributed through the circulation cylinder 8, the second and third switching valves 7, the second switching valve 11, the gas mixing device 12, and the check valve 13, as shown by the arrows in FIG. , the third switching valve 14, and the stock solution tank 1, and then sucked into the circulation cylinder 8 and circulated in the order of the stock solution tank 1, the first switching valve 5, and the first three-way switching valve 6. Next, the circulation cylinder 8
When the inner piston 9a moves to the rightmost position in FIG. 1, the first three-way switching valve 6 is switched, and the β end and the γ end of the first three-way switching valve 6 are communicated with each other. At the same time, the second three-way switching valve 7 is switched, and the α end and the β end of the second three-way switching valve 7 are communicated. Then, when the hydraulic circuit (not shown) is switched and the piston 9b in the actuator 10 is moved back to the left in FIG. 1, the piston 9a in the circulation cylinder 8 is moved to the left in conjunction with this. , the liquid in the circulation cylinder 8 flows from one end of the circulation cylinder 8 to β, γ of the first three-way switching valve 6.
The liquid flows out into the liquid passage 2 through the end, and flows into the circulation cylinder 8 from the other end of the circulation cylinder 8 through the α and β ends of the second three-way switching valve 7. Ru. Therefore, the liquid in the liquid flow path 2 is distributed through the circulation cylinder 8, the first three-way switching valve 6, the gas mixing device 12, the check valve 13, and the third switching valve 14, as shown by the arrows in FIG. , the stock solution tank 1, and then the stock solution tank 1, the first switching valve 5, the second three-way switching valve 7, and then the circulation cylinder 8.
is inhaled and circulated.

In this way, by switching the hydraulic circuit (not shown) and reciprocating the piston 9b in the actuator 10 from side to side, the circulation cylinder 8
The inner piston 9a is reciprocated from side to side, and the liquid within the liquid flow path 2 is circulated.

Next, when measuring the gas content of the liquid in the liquid flow path 2, with the α end and β end of the second three-way switching valve 7 communicating with each other, and with the second switching valve 11 closed, The piston 9a in the circulation cylinder 8 is moved from the right to the left, and liquid is sucked into the circulation cylinder 8 from the other end of the circulation cylinder 8 (see FIG. 2A). Next, in order to reduce the internal pressure of the liquid, the piston 9a in the circulation cylinder 8 is opened while the β and γ ends of the second and third type switching valve 7 are communicated, and the liquid does not flow in from the α end. Move it further to the left (see Figure 2 B). Next, the piston 9a in the circulation cylinder 8 is moved to the right to begin compression. Then, by the pressure sensor 30,
The controller 31 detects that the preset first pressure (low pressure) P ₁ has been reached, and the piston stroke l ₀ at that point is read by the encoder 29 (see FIG. 2C). Further, the pressure sensor 30 detects when the second pressure (high pressure) P ₂ preset by the control device 31 is reached, and the encoder 29 reads the piston stroke l ₂ at that point. These measurement data P ₁ , P ₂ , l ₀ , l ₂
is sent to the calculation unit 32 of the control device 31, and the gas content rate (actual measurement value) Xa is calculated. The calculation method is described below based on Figure 2 C and Figure 3.
The calculation is subject to the following two conditions.

(1) The gas state equation (PV = constant) holds true even when mixed with liquid.

(2) Liquids are incompressible.

And, Pa: Atmospheric pressure (1.033Kg/cm ² ) P ₁ : First pressure condition Kg/cm ² (absolute pressure) P ₂ : Second pressure condition Kg/cm ² (absolute pressure) Vm: Volume of liquid cm ³ Va: Volume of entrained gas under atmospheric pressure Pa, cm ³ V ₁ : Volume of entrained gas under first pressure condition P ₁ , cm ³ V ₂ : Volume of entrained gas under second pressure condition P ₂ , cm ³ V ₀ : Volume of circulation cylinder 8 cm ³ Vf: Total volume of liquid and gas in circulation cylinder 8 under first pressure condition P ₁
cm ³ Vs: Total volume of liquid and gas in circulation cylinder 8 under second pressure condition P ₂
cm ³ Vp: Pipe internal volume cm ³ l ₀ : Distance from encoder 29 origin a to point b where the pressure falls below the first pressure condition P ₁ cm l: Point b where the pressure falls below the first pressure condition P _{1 Distance cm (l=l 2 −}
l ₀ ) D: Diameter of circulation cylinder 8 cm Xa: Volume ratio of liquid and gas under atmospheric pressure (gas content) From the gas state equation PV = constant.

1.033×Va=P ₁ V ₁ = P ₂ V ₂ Therefore, V ₁ = 1.033Va/P ₁ …(1) V ₂ = 1.033Va/P ₂ …(2) V ₁ −V ₂ = 1.033Va (1/ _P1-1 / _P2 )
…(3) Also, Vf＋Vp＝V ₁ +Vm …(4) Further, Vf＝V ₀ −πD ² l ₀ /4 …(5) Substituting formulas (1) and (5) into formula (4), Vm＝Vf＋Vp −V ₁ =V ₀ −πD ² l ₀ /4+Vp −1.033Va/P ₁ …(6) From the condition of circulation cylinder 8, V ₁ −V ₂ =πD ² l/4 …(7) −(3), From formula (7), 1.033Va (1/P ₁ -1/P ₂ ) = πD ² l/4 Therefore, Va=πD ² lP ₁ P ₂ / {4×1.033 (P ₂ - P ₁ )} ...(8) The gas content Xa is determined by Xa=Va/(Vm+Va), so by substituting equations (6) and (8) into this equation, we get Xa=Va/(V ₀ +Vp−πD ² l ₀ /4 −1.033Va /P ₁ +Va) = πD ² lP ₁ P ₂ /Ni where N ₁ = (V ₀ +Vp-πD ² l ₀ /4) x 4 ×1.033 (P ₂ - P ₁ ) + πD ² lP ₂ (P ₁ -1.033 ) Therefore, Xa=πD ² lP ₁ P ₂ /N _2However , N ₂ =4.132 (V ₀ +Vp−πD ² l ₀ /4) (P ₂ −P ₁ )+πD ² lP ₂ (P ₁ −1.033).

The calculation of the above equation is performed in the calculation unit 32 of the control device 31 based on the measurement data P ₁ , P ₂ , l, l ₀ , and the calculation result is the gas mixture setting value stored in advance in the storage unit 33. are compared in the comparison section 34. If the calculated value and the set value are equal, the switching valves 6, 7, and 11 are switched with the gas solenoid valve 18 closed, and the piston 9a of the circulation cylinder 8 is reciprocated to perform the above-mentioned process. The liquid in the liquid flow path 2 is circulated in this manner. In addition, when the calculated value is smaller than the set value, the command unit 35
The gas electromagnetic valve 18 is opened by a command issued from the gas supply source 27, and the gas sent from the gas supply source 27 is mixed into the liquid in the liquid flow path 2 by the gas mixing device 12, and the gas is switched to the circulation cylinder 8. Valve 6, 7, 1
1 circulates the liquid within the liquid flow path 2.
Furthermore, when the calculated value is larger than the set value, the gas solenoid valve 18 remains closed, and the circulation cylinder 8 and the switching valves 6, 7, and 11 are operated to drain the liquid in the liquid flow path 2. While circulating, if necessary, the stock solution tank 1 is replenished with a liquid that is not mixed with gas.

The encoder 29 that detects the position of the piston 9a in the circulation cylinder 8 is not limited to this embodiment, and any mounting structure or detector structure may be used as long as it can detect the position of the piston 9a. . Further, it goes without saying that the means for detecting the pressure within the liquid cylinder 8 is not limited to the pressure sensor 30 described in this embodiment.

As explained above, the present invention includes a pressure detection means for measuring the pressure inside the circulation cylinder that circulates the liquid mixed with gas into the liquid flow path, and a position detection means for detecting the position of the piston of the circulation cylinder. Since a control device is provided that calculates the gas content in the liquid and controls the gas mixing device according to the result, the circulation cylinder can serve both the liquid circulation function and the gas content measurement function. Therefore, the configuration and operation are simpler than conventional devices that include a liquid circulation pump and a gas content measuring device in the liquid flow path. In addition, since a cylinder is provided for liquid circulation, there is little wear even when plastic liquid components (liquids) containing fillers such as glass fibers are circulated, and the life of the device can be greatly extended. It has a good effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
Figure 2 A, B, and C are explanatory diagrams showing the procedure for measuring gas content, Figure 3 shows the state of the liquid and gas in the circulation cylinder 8, and Figure 3 A shows the atmospheric pressure. Fig. 3 (b) is an explanatory drawing showing the state under the first pressure condition P ₁ , Fig. 3 (c) is an explanatory drawing showing the state under the second pressure condition.
FIG. 3 is an explanatory diagram showing a state under pressure condition _P2 . 2...Liquid flow path, 6...First and third type switching valve, 7
... Second and third type switching valve, 8 ... Circulation cylinder,
11...Second switching valve, 12...Gas mixing device, 2
9... Encoder (position detection means), 30... Pressure sensor (pressure detection means), 31... Control device,
9a... Piston.

Claims (1)

[Scope of utility model registration request] It is connected to the stock solution tank via a liquid flow path having a plurality of switching valves, and the reciprocating movement of the piston,
By switching the switching valve in conjunction with this, the liquid mixed with gas by the gas mixing device installed in the liquid flow path is sucked in and discharged, and the liquid is circulated through the liquid flow path to the stock solution tank. A circulation cylinder, a pressure detection means for measuring the pressure inside the circulation cylinder, a position detection means for detecting the position of the piston of the circulation cylinder, an output of the pressure detection means, and an output of the position detection means. Calculate the gas content in the liquid using and compare the calculated value with a predetermined set value,
A device for mixing gas into a liquid, comprising a control device that controls the gas mixing device according to the result.