GB2125308A - Apparatus for nucleating a liquid chemical constituent of a reaction injection molding system - Google Patents
Apparatus for nucleating a liquid chemical constituent of a reaction injection molding system Download PDFInfo
- Publication number
- GB2125308A GB2125308A GB08319435A GB8319435A GB2125308A GB 2125308 A GB2125308 A GB 2125308A GB 08319435 A GB08319435 A GB 08319435A GB 8319435 A GB8319435 A GB 8319435A GB 2125308 A GB2125308 A GB 2125308A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquid chemical
- chemical constituent
- nucleating
- gas
- density
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
- B29B7/76—Mixers with stream-impingement mixing head
- B29B7/7615—Mixers with stream-impingement mixing head characterised by arrangements for controlling, measuring or regulating, e.g. for feeding or proportioning the components
- B29B7/7621—Mixers with stream-impingement mixing head characterised by arrangements for controlling, measuring or regulating, e.g. for feeding or proportioning the components involving introducing a gas or another component in at least one of the components
Abstract
The apparatus includes a tank (10) to which the liquid chemical constituent (e.g. a polyol) is supplied. A relatively inert gas is also supplied to the tank to form a gas blanket above the liquid, the pressure of the gas blanket being maintained at a predetermined value. A recirculation circuit (22, 28) circulates liquid chemical constituent from the tank (10) to a controlled outlet (26) and returns any liquid not passed therethrough to the tank (10), the nucleating gas being introduced into the liquid by means of a mixer (32) through which the liquid flows. The mixer (32) introduces the nucleating gas into the liquid in the direction of flow of the liquid (see Fig. 2 for mixer details). To help maintain a predetermined level of nucleation in the liquid, the gas supply (76, 80) may be controlled to supply gas at a rate proportional to the difference in the required density (i.e. nucleation level) and the density of the nucleated liquid as measured by means (66, 68) in a second recirculation circuit (64). <IMAGE>
Description
SPECIFICATION
Nucleating apparatus
This invention relates to apparatus for nucleating a liquid chemical constituent of a reaction injection molding system.
It is well known to inject gas into a liquid chemical constituent of a reaction injection molding system, such a process being commonly known as nucleation. Such nucleation is necessary to improve the filling of a mold by the molding constituent, thereby improving the quality of the molded product, such as uniform density and surface quality.
To produce good quality molded products, it is desirable to introduce the nucleating gas into the liquid chemical constituent in a manner which ensures thorough mixing of the gas with the liquid.
It is also necessary to accurately control the amount of nucleation in the constituent to a predetermined value which depends upon the nature of the product to be molded. Thus it is necessary to both measure the amount of nucleation and to control the amount of nucleation to show that the predetermined value is maintained.
Various attempts have been made to provide nucleating apparatus which fulfils the above criteria, but such known apparatus has not been as effective as is desirable in present day reaction injection molding systems, especially when fillers are used in the nucleated liquid chemical constituent.
It is therefore an object of the invention to provide an improved nucleating apparatus which overcomes the problems referred to above.
According to the invention, nucleating apparatus comprises a tank, means for supplying the liquid chemical constituent to the tanks, means for supplying a relatively insert gas to the tank to form a gas blanket above the liquid chemical constituent, means for maintaining the pressure of said gas blanket at a predetermined value, a recirculation circuit for circulating liquid chemical constituent from the tank to a controlled outlet and returning liquid chemical constituent not passed through the controlled outlet to the tank, and means for introducing a nucleating gas into liquid chemical constituent in the recirculation circuit, said nucleating gas introducing means comprising a mixer through which liquid chemical constituent in the recirculating circuit flows, said mixer introducing said nucleating gas into the liquid chemical constituent in the direction of flow of the liquid chemical constituent.
It has been found that nucleating apparatus having the combination of features mentioned above provides good quality nucleated liquid chemical constituent with a satisfactorily maintained predetermined level of nucleation.
The mixer may have an aperture through which the liquid chemical constituent passes, and a nozzle in the aperture through which nucleating gas is discharged into liquid chemical constituent passing through the aperture.
The mixer may have a first hollow tubular member having said aperture at one end and into which the liquid chemical constituent flows before passing through said aperture, and a second hollow tubular member within the tubular member and having said nozzle at one end through which the nucleating gas passes before discharge from said nozzle.
The direction of flow of liquid chemical constituent through the aperture of the first hollow tubular member may be substantially perpendicular to the direction of the flow of the liquid chemical constituent into the first hollow tubular member with the nucleating gas following a substantially linear path into the second hollow tubular member and through the nozzle thereof.
The nucleating apparatus may also include means for measuring the density of the nucleated liquid chemical constituent, and means responsive to the measured density to control the flow of nucleating gas into the mixture to maintain the density at a predetermined value.
The nucleating gas flow control means may control the flow of nucleating gas into the mixer at a rate which is proportional to the difference between the measured density and the required predetermined density.
The means for measuring the density of the nucleated liquid chemical constituent may comprise a secondary recirculation circuit and a density measuring device, the secondary recirculation circuit circulating nucleated liquid chemical constituent from the tank past the density measuring device and back to the tank, such a density measuring device comprising a y-ray source from which y-rays pass through the nucleated liquid chemical constituent in the secondary recirculation circuit and y-ray responsive means responsive to y-rays which have passed through the nucleated liquid chemical constituent.
The mixer may be positioned in the recirculation circuit to introduce nucleating gas into the liquid chemical constituent as the liquid chemical constituent returns from the controlled outlet to the tank.
One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of apparatus for nucleating a liquid chemical constituent of a reaction injection molding system, and
Figure 2 is an enlarged view, part in section of a mixer of the apparatus shown in Figure 1.
Referring to the drawings, the nucleating apparatus shown provides a nucleated liquid polyol constituent for a polyurethane molding system for producing polyurethane fascia for automobiles, the other constituent of the system
being a liquid isocyanate constituent.
The liquid polyol constituent is supplied to a
holding tank 10 through an inlet line 12 in the top
of the tank in such a manner as to maintain a
predetermined liquid level in the tank 10, the
predetermined liquid level being automatically maintained in known manner by means of a levelresponsive device which controls an inlet valve (not shown) in the inlet line 12. Also in known manner, the tank 10 contains an agitator 14 driven by a variable speed motor 1 6.
Space in the tank 10 above the liquid polyol constituent is filled with a blanket of gas which is inert with respect to the polyol constituent, for example dry air or nitrogen. The blanket gas enters the tank 10 at the top through an inlet line 18 which includes an electronic pressure regulator 20 set to maintain the blanket gas pressure in the tank 10 at a predetermined value in the range from about 50 to about 55 psi (345 to about 380 kPa) by introducing further gas into the tank whenever the blanket gas pressure falls below the predetermined value. Such pressure assists in maintaining the desired level of nucleation in the polyol constituent. A pressure relief valve 21 is provided at the top of the tank 10 to relieve blanket gas pressure if for some reason the pressure rises to a value greater than about 55 psi (380 kPa).
A recirculation circuit comprises an outlet line 22 containing a pump 24 which pumps polyol constituent from the bottom of the tank 10 to a controlled outlet in the form of a metering cylinder 26 of known kind through which polyol constituent is supplied to a mold (not shown).
Polyol constituent not fed to the mold by the metering cylinder 26 is returned to the upper part of the tank 10 through a line 28. After leaving the metering cylinder 26, the polyol constituent returning along line 28 first passes through a heat exchanger 30 supplied with steam or other heated fluid to maintain the polyol constituent at the desired temperature, usually at about 320 C.
From the heat exchanger 30, the polyol constituent passes through a flow direction changing mixer 32 where a nucleating gas is introduced into the liquid polyol constituent, and the liquid polyol constituent is then passed through an in-line mixer 33 of known kind in which the nucleating gas and liquid polyol constituent are subjected to further mixing to ensure that the freshly introduced nucleated gas and liquid polyol constituent are thoroughly mixed.
The flow direction changing mixer 32 has a key-shaped hollow main body 34 with a polyol constituent inlet 36 leading to a bore 38 in the body 34, the bore 38 having a polyol constituent outlet 40 which is perpendicular to the inlet 36. A gas entry insert 42 is screwed into the end of the main body 34 opposite to the outlet 40, the gas entry insert 42 having a central passage 44 into which nucleating gas is supplied in a manner which will be described in more detail later. A hollow cylindrical polyol direction chamber 46 is located in the bore 38 and has an open end secured by a screw-threaded connection to the gas entry insert 42. The flow direction changer 46 has a series of apertures 48 in its side wall 50, the side wall 50 being spaced from the inner surface of the hollow main body 34.Apertures 48 are in line with the flow of liquid polyol constituent into the mixer 32 through the inlet 36.
A hollow nozzle member 52 is screwed into the inner end of the gas entry insert 42, and has a nozzle 54 extending into an aperture 56 in an inner end wall 58 of the flow direction changer 46, with there being an annular clearance between the nozzle 54 and the wall of the aperture 56.
Down-stream of the aperture 56, the end wall 58 provides an outwardly flared passage 60 leading to the outlet 40. The operation of the flow direction changing mixer 32 will be described later.
The nucleating apparatus also has a secondary recirculation circuit with a pump 62 which pumps liquid polyol constituent along a line 64 from a lower part of tank 10 and back to the top of the tank 1 0. Downstream of the pump 62, the line 64 passes through a density measuring device which has y-ray source 66 on one side of the line 64 and a detection head 68 on the opposite side of the line. The y-ray intensity detected by the detection head 66, that is to say the y-ray intensity after passage of the p-rays from the source 66 through the liquid polyol constituent in the line 64, is dependent on the density of the liquid polyol in the line 64 and accordingly is a measure of the nucleation level, namely the amount of nucleating gas in the liquid polyol component. The higher the nucleation level, the lower the density, and vice-versa.A suitable y-ray source and detection heat unit is made by Texas Nuclear Company.
An electrical density signal from the detection head 68 passes to a transmitter 70, which passes a signal to a controller 72. The controller 72 compares the electrical density signal with a predetermined required density value, and produces an electrical deviation signal which is proportional to the difference between the density signal and the predetermined required density value. The electrical deviation signal is then sent to a transducer 74 where the electrical deviation signal is converted into a corresponding pneumatic deviation signal. The electrical deviation signal is in the range of 4 to 40 mA, and the pneumatic deviation signal is in the range of from about 3 to 1 5 psi (20 to 105 kPa).
The pneumatic deviation signal passes through a pneumatically-operated gas controller 76 connected in a line 78 from a source of nucleating gas, such as dry air of nitrogen, through a check valve 80 to the air inlet 44 of the mixer 32. The
pneumatic deviation signal causes the controller
76 to open by an amount proportional to the
signal so that the amount of air supplied to the
mixer 32 is proportional to the difference between actual liquid polyol constituent density in the
secondary recirculation line 64 and the required
density, i.e. the required nucleating level. A
recorder 82 is associated with the controller 72 to
record the density and deviation signals.
In operation of the apparatus, the level of liquid
polyol constituent in the tank 10 is maintained at
a predetermined height as previously described,
and the nitrogen blanket pressure is maintained at
a predetermined value by the pressure regulator and pressure relief valve 12. Liquid polyol constituent is continuously circulated around the recirculation circuit by the pump 24, with liquid polyol constituent being supplied from metering cylinder 26 to the mold from time to time as required.
Liquid polyol constituent is also continuously circulated around the secondary recirculation circuit by pump 62, and its density is measured by the y-ray density measuring instrument 66, 68.
The deviation from required density, i.e. from the required nucleating level, is sensed and, by means of controller 72, a corresponding amount of air proportional to the deviation of actual density from a required density is passed into the mixer 32.
The liquid polyol constituent passing through the mixer 32 enters through inlet 36, and most of the liquid polyol constituent passes through the apertures 48 into the interior of the flow direction changer 46 and through the aperture 56 in the end wall 58 to the outlet 40. Air enters the mixer 32 through the passage 44 and passes through the nozzle 54, thereby introducing the air into the liquid polyol constituent as it passes through aperture 50. A thorough mixing of the air with the liquid polyol constituent is thereby obtained.
Further mixing is also carried out by in-line mixer 33 and by the agitator 14 in the tank 10.
The apparatus in accordance with the invention is especially useful in cases where the liquid polyol constituent is of relatively high density and/or high viscosity as is the case when a filler is included.
The apparatus may also be used to control nucleation of the liquid isocyanate component of the reaction injection molded system.
Other embodiments of the invention will be readily apparent to a person skilled in the art, the scope of the invention being defined in the appended claims.
Claims (10)
1. Apparatus for nucleating a liquid chemical constituent of a reaction injection molding system, said apparatus comprising a tank, means for supplying the liquid chemical constituent to the tank, means for supplying a relatively inert gas to the tank to form a gas blanket above the liquid chemical constituent, means for maintaining the pressure of said gas blanket at a predetermined value, a recirculation circuit for circulating liquid chemical constituent from the tank to a controlled outlet and returning liquid chemical constituent not passed through the controlled outlet to the tank, and means for introducing a nucleating gas into liquid chemical constituent in the recirculation circuit, said nucleating gas introducing means comprising a mixer through which liquid chemical constituent in the recirculating circuit flows, said mixer introducing said nucleating gas into the liquid chemical constituent in the direction of flow of the liquid chemical constituent.
2. Apparatus according to claim 1 wherein the mixer has an aperture through which the liquid chemical constituent passes, and a nozzle in the aperture through which nucleating gas is discharged into liquid chemical constituent passing through the aperture.
3. Apparatus according to claim 2 wherein the mixer has a first hollow tubular member having said aperture at one end and into which the liquid chemical constituent flows before passing through said aperture, and a second hollow tubular member within the first hollow tubular member and having said nozzle at one end through which the nucleating gas passes before discharge from said nozzle.
4. Apparatus according to claim 3 wherein the direction of flow of liquid chemical constituent through the aperture of the first hollow tubular member is substantially perpendicular to the direction of the flow of the liquid chemical constituent into the first hollow tubular member, and the nucleating gas follows a substantially linear path into the second hollow tubular member and through the nozzle thereof.
5. Apparatus according to claim 1 including means for measuring the density of the nucleated liquid chemical constituent, and means responsive to the measured density to control the flow of nucleating gas into the mixture to maintain the density at a predetermined value.
6. Apparatus according to claim 5 wherein said nucleating gas flow control means controls the flow of nucleating gas into the mixer at a rate which is proportional to the difference between the measured density and the required predetermined density.
7. Apparatus according to claim 5 wherein the means for measuring the density of the nucleated liquid chemical constituent comprises a secondary recirculation circuit and a density measuring device, the secondary recirculation circuit circulating nucleated liquid chemical constituent from the tank past the density measuring device and back to the tank, said density measuring device comprising y-ray source from which y-ray pass through the nucleated liquid chemical constituent in the second recirculation circuit and y-ray responsive means responsive to y-rays which have passed through the nucleated liquid chemical constituent.
8. Apparatus according to claim 1 wherein the mixer is positioned in the recirculation circuit to introduce nucleating gas into the liquid chemical constituent as the liquid chemical constituent returns from the controlled outlet to the tank.
9. Apparatus for nucleating a liquid chemical constituent of a reaction injection molding system, said apparatus comprising a circuit for supplying liquid chemical constituent to a controlled outlet, means for introducing a nucleating gas into liquid chemical constituent in the circuit, and means for measuring the density of the nucleated liquid chemical constituent, said nucleating gas introducing means comprising a mixer through which liquid chemical constituent in the circuit flows, said mixer introducing said nucleating gas into the liquid chemical constituent in the direction of flow of the liquid chemical constituent and at a rate which is proportional to the difference between the measured density and the required predetermined density.
10. Apparatus for nucleating a liquid chemical constituent of a reaction injection molding system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA408533 | 1982-07-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8319435D0 GB8319435D0 (en) | 1983-08-17 |
| GB2125308A true GB2125308A (en) | 1984-03-07 |
Family
ID=4123320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08319435A Withdrawn GB2125308A (en) | 1982-07-30 | 1983-07-19 | Apparatus for nucleating a liquid chemical constituent of a reaction injection molding system |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3326961A1 (en) |
| FR (1) | FR2530970A1 (en) |
| GB (1) | GB2125308A (en) |
| IT (1) | IT1163859B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3920472A1 (en) * | 1989-06-22 | 1991-01-10 | Tuchenhagen Otto Gmbh | Bubble column for aerating beer wort - stops a required concn. when undissolved air is centrifugally sepd. |
| GB2290725A (en) * | 1994-06-30 | 1996-01-10 | Procter & Gamble | Static mixer for liquids having regulated gas inlet |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3544914A1 (en) * | 1985-12-19 | 1987-06-25 | Elastogran Masch Bau | DEVICE FOR PRODUCING A REACTION MIXTURE FROM AT LEAST TWO PLASTIC COMPONENTS |
| DE4235970C1 (en) * | 1992-10-26 | 1993-11-25 | Bayer Ag | Device for producing a foam-forming reaction mixture |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1417377A (en) * | 1973-04-05 | 1975-12-10 | Hennecke Gmbh Maschf | Method of and a machine for manufacturing foam especially polyurethane foam from a free-flowing reaction mixture |
| GB1552476A (en) * | 1975-10-04 | 1979-09-12 | Bayer Ag | Process and apparatus for the preparation of a reaction mixture for the production of plastics foams |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD133642B1 (en) * | 1977-10-26 | 1982-05-26 | Plast Und Elast Veb Verarbeitungsmasch Komb | DEVICE FOR DOSING AND INTERMEDIATE GASES IN STROEMEN MEDIA |
| US4312820A (en) * | 1980-08-21 | 1982-01-26 | General Motors Corporation | Process and apparatus for nucleation control adapted for reaction injection molding of cellular products |
-
1983
- 1983-07-19 GB GB08319435A patent/GB2125308A/en not_active Withdrawn
- 1983-07-26 IT IT22252/83A patent/IT1163859B/en active
- 1983-07-27 DE DE19833326961 patent/DE3326961A1/en not_active Withdrawn
- 1983-07-29 FR FR8312592A patent/FR2530970A1/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1417377A (en) * | 1973-04-05 | 1975-12-10 | Hennecke Gmbh Maschf | Method of and a machine for manufacturing foam especially polyurethane foam from a free-flowing reaction mixture |
| GB1552476A (en) * | 1975-10-04 | 1979-09-12 | Bayer Ag | Process and apparatus for the preparation of a reaction mixture for the production of plastics foams |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3920472A1 (en) * | 1989-06-22 | 1991-01-10 | Tuchenhagen Otto Gmbh | Bubble column for aerating beer wort - stops a required concn. when undissolved air is centrifugally sepd. |
| GB2290725A (en) * | 1994-06-30 | 1996-01-10 | Procter & Gamble | Static mixer for liquids having regulated gas inlet |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8319435D0 (en) | 1983-08-17 |
| FR2530970A1 (en) | 1984-02-03 |
| IT8322252A1 (en) | 1985-01-26 |
| DE3326961A1 (en) | 1984-02-02 |
| IT8322252A0 (en) | 1983-07-26 |
| IT1163859B (en) | 1987-04-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |