JPS6216185Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an apparatus that mixes gas such as air into a urethane raw material in order to improve the quality of molded products.

(Prior art) When performing RIM (Reaction Iojection Molding), in order to minimize the variation in the density of the resulting molded product and improve the surface quality, a certain amount of gas, such as dry air or other injector, is added to the urethane raw material in advance. May contain active gases. A urethane raw material gas mixing device is used as a device for continuously and accurately mixing gas such as dry air into the urethane raw material. The urethane raw material gas mixing device has a raw material tank filled with urethane raw material, a sub-tank that communicates with the liquid part of the raw material tank, and a density measuring tank that communicates with two points at different heights of the sub-tank via hoses. It measures the density of the urethane raw material flowing in the sub-tank and compares the measured density with the set density to continuously provide feedback on the amount of gas such as dry air mixed into the urethane raw material. I had it under control.

As shown in FIG. 1, the hose 2 connects and communicates two points at different heights of the liquid part in the sub-tank 1 with a differential pressure detection device for density measurement (not shown).
In order to more accurately detect the differential pressure, urethane raw material A' with no gas mixed in was injected into the chamber. Note that 3 indicates a nipple and 4 indicates a hose cap. However, the urethane raw material contained in the hose 2 between the sub-tank 1 and the differential pressure detection device
A′ is the urethane raw material A flowing inside the subtank 1.
As the urethane raw material A' remains stagnant without moving like this, the urethane raw material A' inside the hose 2 easily deteriorates during long-term use, and the urethane raw material A'
If A' is a highly reactive liquid, hose 2
The pressure difference of urethane raw material A may not be detected by the differential pressure detection device due to reaction and sticking within the urethane raw material A. As a result, it becomes difficult to accurately measure the density of urethane raw material A, and the urethane raw material A is There was a problem in that it became impossible to perform stable and accurate feedback control of the gas.

(Purpose of the invention) The purpose of the invention is to solve the above problem, and its purpose is to prevent the liquid from deteriorating or sticking in the hose that communicates the sub-tank with the differential pressure detection device for density measurement. An object of the present invention is to provide a urethane gas mixing device that stably maintains accurate differential pressure detection by a differential pressure detection device.

(Structure of the invention) For this reason, the structure of the invention is that, in addition to the sub-tank that communicates with the liquid part of the raw material tank filled with urethane raw materials, a hose is connected to two points at different heights of the liquid part of the sub-tank. A measuring differential pressure detecting device is installed, a partitioning thin film is provided between the sub-tank and the hose, and a liquid different from the urethane raw material is sealed in a chamber on the side of the density measuring differential pressure detecting device with the thin film as a boundary. It is characterized by

(Function) With this configuration, a liquid with low deterioration and reactivity can be selected and sealed in the hose that communicates the sub-tank with the differential pressure detection device, thereby preventing deterioration and reaction sticking of the liquid in the hose. This can be prevented and an accurate differential pressure detection device can be stably maintained.

(Example) Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. Fig. 2 is an overall system diagram of this embodiment, and 5 is a raw material tank filled with urethane raw material A; Urethane raw material A is supplied from a raw material supply hose (not shown). The raw material tank 5 is equipped with an agitator 6;
The rotating shaft of is directly connected to the drive motor 7. 8 is a pump for pumping the urethane raw material A filled in the raw material tank 5 into a mold (not shown).

A sub-tank 9 communicates with the liquid portion of the raw material tank 5 via a circulation hose 10, and a portion of the urethane raw material A filled in the raw material tank 5 flows into the sub-tank 9. As shown in FIG. 3, thin film fixing blocks 11 are installed at the upper (upstream side) and lower (downstream side) of the liquid part of the sub-tank 9, respectively.
and a high pressure hose 13 via the nipple 12,
The upper end of the low pressure hose 14 is connected, and the lower ends of the high pressure hose 13 and the low pressure hose 14 are connected to the high pressure side pressure receiving part 15 of the differential pressure detection device 15 for density measurement, respectively.
a, connected to the low pressure side pressure receiving part 15b.

Here, both the hoses 13, which are connected to the sub-tank 9 via the block 11 and the nipple 12,
Regarding the mounting structure near the upper end of Hose 1
3 and 14 have exactly the same structure, and to explain the upper end of the high pressure hose 13 as an example,
As shown in the figure, the block 11 is provided with a thin film 16, which partitions the block 11 into a chamber on the sub-tank 9 side and a chamber on the hose 13 side. Then, in the chamber on the high-pressure side pressure receiving part 15a side of the differential pressure detection device 15 with the thin film 16 as a boundary, a liquid B different from the urethane raw material A, more specifically a liquid B with low cooling property, reaction, and sticking property, such as silicon oil, DOP
(dioctyl phthalate) etc. are selected and enclosed. In FIGS. 3 and 4, reference numeral 17 designates a sealed liquid inlet provided at the upper part of the nipple 12, and reference numeral 18 designates a hose cap that reliably connects the nipple 12 and the hose 13 or 14.

The differential pressure detection device 15 has a function of detecting the differential pressure ΔP between the upper and lower set points of the urethane raw material A flowing through the sub-tank 9, and the differential pressure ΔP detected by the differential pressure detection device 15 is converted into density. It is designed to be output as an electrical signal. 19 is an amplifier for this output signal; 20 is a density recorder that receives the output signal and continuously and automatically records and displays the density of the urethane raw material A; the density recorder 20 converts the output signal into a preset density It also has the function of generating a comparison signal.

21 is a cylinder filled with dry air or inert gas, and 22 is a circulation hose 23 connected to the raw material tank 5.
A gas supply hose 24 connects the cylinder 21 and the gas mixture tank 22 through the gas mixture tank.
A control valve 25 is provided in the middle. The opening and closing of the control valve 25 is controlled by a comparison signal transmitted from the density recorder 20. In addition, the gas mixing tank 22
and the sub-tank 9 are connected and communicated by a circulation hose 26, and a pump 27 is provided in the middle of the circulation hose 26 for pressure-feeding the urethane raw material A in the sub-tank 9 to the gas mixing tank 22.

The gas mixing device configured as described above detects the differential pressure ΔP between the upper and lower points of the urethane raw material A in the sub-tank 9 via the hoses 13 and 14 in the differential pressure detection device 15. is converted into density and an output signal is sent to the density recorder 20. When the density recorder 20 receives the output signal, it compares it with a preset set density and generates a comparison signal, and this comparison signal is sent to the control valve 25 to control the opening and closing of the control valve 25. An appropriate amount of gas such as dry air is supplied from 21 to the gas mixing tank 22, and the urethane raw material A that has been thoroughly stirred and mixed with the gas such as dry air in the gas mixing tank 22 is circulated and supplied to the raw material tank 5.
As a result, a predetermined amount of gas such as dry air is mixed into the urethane raw material A in the raw material tank 5.

Here, the hose 13, 1, which had been a problem in the past,
Regarding the deterioration or sticking phenomenon of the sealed liquid in the block 11, a partitioning thin film 16 is provided in the block 11 to partition the sub-tank 9 and the hoses 13, 14, and the chambers on the pressure receiving parts 15a, 15b side with the thin film 16 as a boundary are Since liquid B with low deterioration, reaction, and stickiness is selected and sealed, liquid B remains in the hoses 13 and 14 even during long-term use like in the past.
It is possible to effectively prevent the deterioration or reaction-fixation of the particles. Therefore, accurate differential pressure detection by the differential pressure detection device 15 is stably maintained, and density control of the urethane raw material A can be performed accurately and stably.

(Effects of the invention) As explained above, according to the invention, a liquid with low deterioration, reaction, and stickiness is placed in the chamber on the side of the differential pressure detection device with the thin partition film provided between the sub-tank and the hose as a boundary. Since the liquid can be selected and sealed, it prevents the liquid from easily deteriorating, reacting, and sticking inside the hose even during long-term use, and allows accurate differential pressure detection using a differential pressure detection device. Pressure detection is maintained, the density of the urethane raw material can be accurately and stably controlled, and this has the effect of greatly contributing to improving the quality of molded products.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional side view showing the main parts of a conventional device, Fig. 2 is an overall system diagram showing an embodiment of the present invention, and Fig. 3 is a side view of the main parts showing the mounting position of the upper end of the hose according to the present invention. 4 are enlarged side sectional views showing the mounting structure near the upper end of the hose according to the present invention. 5...Raw material tank, 9...Sub tank, 13...
...High pressure hose, 14...Low pressure hose, 15...
...Differential pressure detection device for density measurement. A, A'...Urethane raw material, B...Liquid (liquid different from the urethane raw material).

Claims (1)

[Scope of utility model registration request] Outside the sub-tank that communicates with the liquid part of the raw material tank filled with the urethane raw material, a differential pressure detection device for density measurement is provided which communicates via a hose with two points at different heights of the liquid part of the sub-tank, and A urethane raw material gas mixing device characterized in that a partitioning thin film is provided between the sub-tank and the hose, and a liquid different from the urethane raw material is sealed in a chamber on the side of the differential pressure detection device with the thin film as a boundary.