JPS58108116A - Mixing device for gas in urethane material - Google Patents

Abstract

PURPOSE:To obtain a molded article having uniform quality, by measuring successively the density of urethane material, by mixing in the urethane material a gas in a quantity corresponding to a value obtained from measurement, and by maintaining thereby the density of the material at an arbitrary constant value. CONSTITUTION:Urethane material supplied to a material tank 1 is agitated by an agitator 1a, and most of it is supplied to a molding die via an injection pipe 4. Meanwhile, a part of it is sent to a gas mixing tank 6 through a subtank 5 and mixed with air in a cylinder 8 via a valve 10, and then is circulated in the material tank 1. A differential pressure oscillator 11 is attached to the abovementioned device to measure a pressure difference P between the upper- stream and down-stream sides of the subtank 5. The measured difference is converted into the density of the material urethane, and then this is sent to a metering-recording regulator 14 (a mark 14a denotes a display board) and compared with the set density of material. Based on a difference signal thus obtained, a quantity of air to be mixed in is controlled through the intermediary of the valve 10, and thereby the density of the urethane material 2 in the tank 1 is maintained at a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a urethane raw material gas mixing device.

When performing RIM molding, if a certain amount of fine gas, such as air or other inert gas, is mixed into the urethane raw material in advance, the density of the finished product will be uniform and the quality will be improved. It has been known. Conventionally, the method for mixing gas into urethane raw materials is to collect a certain amount of raw material from a urethane raw material tank, measure the density of this sample, and calculate the amount of gas mixed in from the obtained sample density.
A specified amount of gas was mixed into the urethane raw material.
' However, in the above method, sampling is performed at regular intervals to calculate the required amount of gas mixture, so if there is a change in the density of the urethane raw material during the period, it cannot be dealt with quickly. In addition, since most of the operations are manual, there are problems in that it is labor-intensive and the measurement accuracy is poor. Therefore, in the above-mentioned method, it was not possible to always continuously supply the optimum amount of gas to the urethane raw material.

In the present invention, by continuously measuring the density of the urethane raw material and mixing an amount of gas corresponding to the measured density into the urethane raw material, the density of the urethane raw material can be maintained at a constant value. It provides a fully automated gas entrainment device.

That is, the urethane raw material gas mixing device of the present invention includes a raw material tank filled with a urethane raw material, a urethane raw material circulation path in which a part of the urethane raw material in the raw material tank is released from a tack and circulated, and a urethane raw material circulation *a. a sub-tank provided in the middle of the path, a gas generator, a gas supply route for supplying the gas generated from the gas generator to the urethane raw material, a gas flow rate adjustment valve interposed in the gas supply route; Detecting the pressure difference between set points at the upstream and downstream of the urethane raw material located below the sub-tank and flowing down in the sub-tank, and converting this into density;
A urethane raw material density measuring device that can output a signal, and an output signal from this density measuring device to compare the density of the urethane raw material with a set density and output a control signal for operating the gas flow rate regulating valve. It is characterized by comprising a comparison circuit that can perform

Hereinafter, the apparatus of the present invention will be explained based on the drawings.

In the following example, air will be used as the gas mixed into the urethane raw material, but the present invention is not limited to air, and other commonly used gases, such as N
,, Of course, He, Ar, and chlorofluorocarbon gases are also applicable.

FIG. 1 is a schematic diagram showing an example of the apparatus of the present invention. In FIG. Raw material 2 is supplied. The raw material tank 1 is of a closed type and is equipped with a stirrer 1m, and this stirrer 1aij is operated by a motor 1bK attached to the upper surface of the raw material tank 1.

On the bottom of the raw material tank 1, there is a urethane raw material circulation pipe 5,
A mold injection pipe 4 for supplying the urethane raw material 2 to the mold (not shown) is connected. 4m is a pump for supplying the urethane raw material 2 to the mold.

The circulation pipe 3 is provided with a sub-tank 5 for measuring the density of the urethane raw material and an air mixing tank 6 on the way, and a part of the urethane raw material 2 is constantly circulated through the pipe 3 by a pump 7 .

The sub-tank 5 is located below the bottom surface of the raw material tank 1, and is placed so that its longitudinal axis is parallel to the flow direction of the urethane raw material.

One end of an air supply pipe 9 coming out of the cylinder 8 is connected to the air mixing tank 6, and an air flow rate regulating valve 10 is interposed in the middle of the air supply pipe 9. Further, the air mixing tank 6 is equipped with a stirrer (not shown), and can sufficiently stir and mix the urethane raw material and air.

11 is a differential pressure oscillator that detects the pressure difference (ΔP) between the upstream and downstream set points of the urethane raw material flowing through the sub-tank 5 and converts this into density; Convert pressure (ΔP) to density [,
and an amplifying section 112 that outputs it as a signal. The pressure receiving section 111 includes a high pressure side pressure receiving section 111a and a low pressure side pressure receiving section 111.
The high pressure side pressure receiving part 111aK is connected to one end of the upstream pipe 12, and the low pressure side pressure receiving part 111bK is connected to one end of the downstream pipe 13.

The other end of the upstream pipe 12 opens at the upper part of the sub-tank 5 in the downstream direction, and the other end of the downstream pipe 13 opens at the lower part of the sub-tank 5 in the downstream direction. These two tubes 12.1! The distance of the opening in the sub-tank 5 of I is a predetermined value, for example! Set 100mg. Upstream pipe 12
The downstream pipe 13 is filled with pure urethane raw material.
1.

The differential pressure oscillator 11 is installed at a position below the opening of the lower part of the sub-tank 5 in the flow direction, so that Kfl is not determined.

The density of the urethane raw material measured by the differential pressure oscillator 11 is sent to the recording controller 14 as a signal 15.

Recording controller 14q, the differential pressure oscillator 11 and electrical Kll
The signal sent from the differential pressure oscillator 11 is displayed on a scale and can be compared with a preset density.

A comparison signal 16 obtained from this K is connected to the air flow rate regulating valve 10 to control the air flow rate.

The method of measuring the differential pressure ΔP in the sub-tank 5 and converting it into density will be explained in more detail with reference to Figure 2.

FIG. 2 is an explanatory diagram showing the principle of detecting the density of urethane raw material. As shown in the figure, the urethane raw material 2 (density ρ0) supplied from the circulation pipe 5 flows down into the sub-tank 5 from above as indicated by the arrow in the figure. The upstream pipe 12 and the downstream pipe 13 are filled with pure undiluted urethane raw material (density p),
The lower end of the upstream pipe 12 is connected to the right half of the differential pressure oscillator pressure receiving part 111 (
Further, the lower end of the downstream pipe 13 is connected to the left half (low pressure side) 111bK of the differential pressure oscillator pressure receiving section -111.

In the differential pressure oscillator 11 described above, the pressure HP applied to the high pressure side is obtained by the following equation (1).

Hp=(he +3no)Xρ+(hh, -3no
) Xpo "' (Low pressure side 131 of II differential pressure oscillator
b [The applied pressure Lp is obtained by the following equation (2).

LP=h@Xρ+(h he )Xpo”
(2) However, in the above formulas (1), , and (2), h represents the height from the top surface of the differential pressure oscillator 11 to an arbitrary position of the circulation pipe 3 above the sub-tank 5. ,
It represents the height from the reference position of the hoFi differential pressure oscillator 11 to the opening position of the downstream pipe 13 in the sub-tank 5. Talented,
300 is a numerical value representing the distance (■) between the opening position of the upstream pipe 12 and the opening position of the downstream pipe 15.

From the above formula (Il, (2)), the pressure difference (ΔP) between the high pressure side 111m and the low pressure side 111b of the differential pressure oscillator 11 is calculated by the following formula %
Formula % ) () Here, the differential pressure (ΔP) between the opening position of the upstream pipe 12 and the opening position of the downstream pipe 13 is set to 75, and the density of the pure urethane raw material is assumed to be ρ = 1 g/CC. Then, from equation (3), ΔP=300(1-po)=75 ρ·=α75 (#/CC). Therefore, when the differential pressure ΔF = 75 mH10, the density ρ0 of the urethane raw material is 0.7517cc.

Further, when the differential pressure ΔP=mouth, the density of the urethane raw material is ρoId 111/cc by calculation similar to the above.

The numerical values in the range obtained by the above calculation are displayed on the recording controller 14 as a scale plate 141.

Note that the density of the pure urethane raw material is not necessarily p = tO. In this case, the density of the pure urethane raw material used (ρ
) into the above equation (3), calculate the differential pressure 0 to 75 µH, OK corresponding, b density, and replace the scale plate to obtain the actual density of the urethane raw material.

For example, when the density of the pure urethane raw material is ρ=105, the display on the scale plate 14a will be 105 to 0.6.

The recording controller 14 displays the density of the urethane raw material flowing through the sub-tank 5 as described above, compares the measured value with a set value, and generates a signal to operate the valve 10 that controls the amount of air mixed in. It has a built-in comparison circuit that can

In the device f having the above configuration, the urethane raw material 2 is supplied to the raw material tank 1 through a separate route. A portion of the supplied urethane raw material 2 flows down the sub-tank 5 from the circulation pipe 3, enters the gas mixing tank 6, and is further circulated to the raw material tank 2!
L, there.

Differential pressure oscillation occurs in the upstream and downstream pressure difference in the urethane raw material 2 flowing down the sub tank 5! ! 11 to detect the density. This density is transmitted from the differential pressure oscillator 11 to the performance controller 14 as an output signal 15. In the recording controller 14,
This density is displayed on the display board 14 and compared with a preset density.

If the constant density is greater than the set density, a signal 16 is sent to the valve 10 to open the valve 17 and air is supplied to the gas mixing tank 6.
supply to The urethane raw material sufficiently stirred and mixed with the supplied air in the gas mixing tank 6 is circulated to the raw material tank 1, and then [7
Therefore, air is mixed into the urethane raw material 2 in the raw material tank 1.

By continuously performing the above operations, the density of the urethane raw material 2 in the raw material tank 1 can be brought close to the set value. In addition, even after adjusting the density to near the set value, if the urethane raw material is constantly accumulated, changes in density can be continuously detected by K, so air can be mixed in as appropriate according to this density. For example, urethane raw material v
The R degree can always be kept at a constant value. In addition, the recording adjustment needle can be adjusted by changing the setting value appropriately.
The density of the urethane raw material 2 in the raw material tank 1 can be changed, and therefore, when used as a raw material for RIM molding, it is possible to obtain a raw material with an optimal density, that is, a mixture with an optimal amount of air, depending on the molding conditions. It has the advantage of being able to

In addition, in the apparatus shown in FIG. 1, after uniformly mixing the urethane raw material and air in the air mixing tank 6,
Since the air in the urethane raw material 2 in the raw material tank 1 is finely and uniformly dispersed, the R
The density in the urethane product during IM molding becomes uniform. However, if the raw material tank 1 is equipped with sufficient stirring equipment, air can be supplied directly to the raw material tank 1 without being supplied to the gas mixing tank 6.

As is clear from the above article, the device of the present invention adjusts the amount of air mixed into the urethane raw material by measuring the urethane raw material density, and this density measurement is automatically and continuously carried out. This makes it possible to accurately control the amount of gas mixed into the urethane raw material.
However, if this machine is applied to a RIM molding system, it is possible to obtain a polyurethane raw material in which fine gases are uniformly dispersed, so that the entire molded product has a uniform density distribution, and the resulting product has a uniform density distribution. It has the effect of improving physical properties.

[Brief explanation of drawings]

FIG. 1 is a schematic process diagram showing an example of the apparatus of the present invention, and FIG. 2 is an explanatory diagram of the main part of FIG. In the figure, 1... [material tank, 2... urethane raw material, 3...
Circulation pipe, 5... sub tank, 6... air mixing tank,
9...Air supply pipe, 1o...Air flow rate adjustment valve, 11
... Differential pressure oscillator, 111 ... Pressure receiving section, 112 ...
Amplification section, 12... Upstream pipe, 15... Downstream pipe, 14
... Recording adjustment needle, Patent applicant Toyota Motor Corporation Toho Machinery Co., Ltd. Fig. 1 [

Claims (1)

[Scope of Claims] A raw material tank filled with a urethane raw material, a urethane raw material circulation path that takes out a portion of the urethane raw material from the tank and circulates it, a sub-tank provided in the middle of the urethane raw material circulation path, and a gas. a gas generation device; a gas supply path for supplying the gas generated from the wrinkled gas generator to the urethane raw material; a gas flow rate adjustment valve interposed in the wrinkled gas supply path;
゛Urethane raw material 11 degree measuring device located below the sub-tank and capable of measuring the pressure difference between upstream and downstream of the urethane raw material flowing down in the sub-tank, converting it into density, and outputting it as a signal. and a comparison circuit capable of comparing the density of the urethane raw material and the membrane chamber density based on the output signal from the 11 degree measuring device and outputting a control signal for operating the gas flow rate regulating valve. Raw material gas mixing device.