CA2060566A1 - Mix head for the production of a flowable reaction mixture - Google Patents
Mix head for the production of a flowable reaction mixtureInfo
- Publication number
- CA2060566A1 CA2060566A1 CA002060566A CA2060566A CA2060566A1 CA 2060566 A1 CA2060566 A1 CA 2060566A1 CA 002060566 A CA002060566 A CA 002060566A CA 2060566 A CA2060566 A CA 2060566A CA 2060566 A1 CA2060566 A1 CA 2060566A1
- Authority
- CA
- Canada
- Prior art keywords
- mixing chamber
- reaction mixture
- depressions
- mix head
- cleaning piston
- 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.)
- Abandoned
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
- B29B7/7663—Mixers with stream-impingement mixing head the mixing head having an outlet tube with a reciprocating plunger, e.g. with the jets impinging in the tube
-
- 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
- B29B7/7663—Mixers with stream-impingement mixing head the mixing head having an outlet tube with a reciprocating plunger, e.g. with the jets impinging in the tube
- B29B7/7684—Parts; Accessories
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
MIX HEAD FOR THE PRODUCTION OF
A FLOWABLE REACTION MIXTURE
ABSTRACT OF THE DISCLOSURE
Jamming of the cleaning piston of a mix head for the production of a flowable reaction mixture is avoided by providing depressions in the form of annular grooves alternating with lands in the wall of the mixing chamber bore (3) in which reaction mixture cures to an elastic mass.
Mo3726 Le A 28 195-US/CA
A FLOWABLE REACTION MIXTURE
ABSTRACT OF THE DISCLOSURE
Jamming of the cleaning piston of a mix head for the production of a flowable reaction mixture is avoided by providing depressions in the form of annular grooves alternating with lands in the wall of the mixing chamber bore (3) in which reaction mixture cures to an elastic mass.
Mo3726 Le A 28 195-US/CA
Description
2 ~
MIX HEAD FOR THE PRODUCTION OF
A FLOWABLE REACTION MIXTURE
BACKGROUND OF T~HE INVEN~ION
The invention relates to a mix head for the production of a flowable reaction mixture forming solid or cellular plastic material. The mix head broadly comprises a body with a mixing chamber bore in which a cleaning piston is driven and into which injection openings for the reaction components discharge.
The wall of the bore has depressions.
lo The cleaning piston of the mixing head described in U.S.
Patent 3,263,928 serves simultaneously for the clearing of the injection openings for the mixing process while being returned to a rear dead point position. After conclusion of the mixing process, the cleaning piston travels to the forward dead point position and thereby ejects the mixture residues remaining in the mixing chamber bore. In order to ensure sufficient sliding ability7 during the manufacture of the device, the mixing chamber bore and cleaning piston are made to fit accurately with a small clearance between the sliding surfaces. After repeated mixing operations, the sliding clearance between the cleaning piston and mixing chamber wall fills with cured reaction mixture, which is molded to a film of highly compacted material. With time the film of material jams the cleaning piston. The piston can then be made movable again only by heating the mixing chamber body. The mixing chamber wall must then be cleaned. While cleaning pistons of small diameter the piston can be broken.
In order to prevent jamming of the cleaning piston, attempts have been made to provide depressions in the cylindrical surface of the cleaning piston which overlap in the circumferential direction (see European patent 1,009,114).
This weakens the cleaning piston and makes it even more likely that the piston will break. The curing matPrial extends outwards from the depressions into the sliding clearance, as a Le A ?8 195-US/CA
2~9~
result of which the formation of a film of mixture filling the sliding clearance occurs. The formation of material occurs on the cylindrical surface of the cleaning piston between the depressions and not on the wall of the mixing chamber bore.
~he risk of jamming and breakage of the cleaning piston is thus even increased.
U.S. patent 3,799,199 discloses a mix head which has grooves arranged paraxially in the cylindrical surface of the cleaning piston which grooves are connected to each other at the upper and lower ends of the cleaning piston by means of a groove extending around the periphery of the piston. The paraxial grooves can also be arranged in the wall of the mixing chamber bore. This embodiment also does not eliminate the risk of jamming since the film of mixture in the sliding clearance is not adequately stripped off.
The problem exists of designing a mix head wherein the jamming of the cleaning piston can be excluded.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the mix head with the cleaning piston in the cleaning position, Figure 2 shows an enlargement of the mixing chamber of the mix head with the cleaning piston in the cleaning position, and, Figure 3 shows an enlargement of the mixing chamber without the cleaning piston.
DESCRIPTION OF THE INVENTION
The above noted problem is solved by the fact that annular grooves, or depressions, are arranged in the wall of the mixing chamber bore over the entire length of the bore, at right angles to the axis of the mixing chamber bore. Surprisingly, the arrangement of the grooves, or depressions, in the wall of the mixing chambers bore instead of in the cleaning piston has a completely different effect. The depressions fill very rapidly with curing mixture which adheres therein. As a result of a particular geometry of the depressions, especially having Mo3726 Le A 28 195-US!CA
2~0~6~ ~
a sufficient depth, the adhesion can be optirnized. Since the material cured in the depressions has a certain elasticity, when released by the cleaning piston it bulges into the mixing chamber bore. The bulge is only of a few tenths of a millimeter. On the next ejection stroke of the cleaning piston, the front edge of the piston not only scrapes off this protruding bulge, but also drags out some of the material from the grooves, or depressions, due to the elasticity of the material. Simultaneously in the ejection stroke, the film of mixture present in the sliding clearance is stripped off into the freshly produced cavities in the material of the depressions. This new material cures and again bulges into the mixing chamber bore during the return of ejector piston into its mixing position, which corresponds the rear dead point, and so on.
The new embodiment is especially favorable since the edges surrounding the grooves, or depressions, function as stripping edges. Differently shaped depressions, such as for example troughs, are also possible. It is important in this connection only that the depressions be at least tangential to each other in the circumferential direction of the mixing chamber bore.
It is preferred that they overlap, in order that stripping of the film of mixture is possible over the whole circumference.
Nevertheless the depressions must necessarily be interrupted in the area of the injection openings in order that there be sufficient wall around the injection openings. The depth, a, and the width, b, of the annular grooves as well as the thickness, c, of the lands (i.e, the area surrounding the grooves) naturally depend on the diameter of the cleaning piston and the diameter of the mixing chamber bore. The greater is this diameter the greater are the dimensions of the annular grooves and lands.
Even if the annular grooves disclosed in U.S. patent 3,799,199 at the upper and lower ends of the cleaning piston were moved to the wall of the mixing chamber bore, the Mo3726 Le A 28 195-US/CA
2~ 6~
MIX HEAD FOR THE PRODUCTION OF
A FLOWABLE REACTION MIXTURE
BACKGROUND OF T~HE INVEN~ION
The invention relates to a mix head for the production of a flowable reaction mixture forming solid or cellular plastic material. The mix head broadly comprises a body with a mixing chamber bore in which a cleaning piston is driven and into which injection openings for the reaction components discharge.
The wall of the bore has depressions.
lo The cleaning piston of the mixing head described in U.S.
Patent 3,263,928 serves simultaneously for the clearing of the injection openings for the mixing process while being returned to a rear dead point position. After conclusion of the mixing process, the cleaning piston travels to the forward dead point position and thereby ejects the mixture residues remaining in the mixing chamber bore. In order to ensure sufficient sliding ability7 during the manufacture of the device, the mixing chamber bore and cleaning piston are made to fit accurately with a small clearance between the sliding surfaces. After repeated mixing operations, the sliding clearance between the cleaning piston and mixing chamber wall fills with cured reaction mixture, which is molded to a film of highly compacted material. With time the film of material jams the cleaning piston. The piston can then be made movable again only by heating the mixing chamber body. The mixing chamber wall must then be cleaned. While cleaning pistons of small diameter the piston can be broken.
In order to prevent jamming of the cleaning piston, attempts have been made to provide depressions in the cylindrical surface of the cleaning piston which overlap in the circumferential direction (see European patent 1,009,114).
This weakens the cleaning piston and makes it even more likely that the piston will break. The curing matPrial extends outwards from the depressions into the sliding clearance, as a Le A ?8 195-US/CA
2~9~
result of which the formation of a film of mixture filling the sliding clearance occurs. The formation of material occurs on the cylindrical surface of the cleaning piston between the depressions and not on the wall of the mixing chamber bore.
~he risk of jamming and breakage of the cleaning piston is thus even increased.
U.S. patent 3,799,199 discloses a mix head which has grooves arranged paraxially in the cylindrical surface of the cleaning piston which grooves are connected to each other at the upper and lower ends of the cleaning piston by means of a groove extending around the periphery of the piston. The paraxial grooves can also be arranged in the wall of the mixing chamber bore. This embodiment also does not eliminate the risk of jamming since the film of mixture in the sliding clearance is not adequately stripped off.
The problem exists of designing a mix head wherein the jamming of the cleaning piston can be excluded.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the mix head with the cleaning piston in the cleaning position, Figure 2 shows an enlargement of the mixing chamber of the mix head with the cleaning piston in the cleaning position, and, Figure 3 shows an enlargement of the mixing chamber without the cleaning piston.
DESCRIPTION OF THE INVENTION
The above noted problem is solved by the fact that annular grooves, or depressions, are arranged in the wall of the mixing chamber bore over the entire length of the bore, at right angles to the axis of the mixing chamber bore. Surprisingly, the arrangement of the grooves, or depressions, in the wall of the mixing chambers bore instead of in the cleaning piston has a completely different effect. The depressions fill very rapidly with curing mixture which adheres therein. As a result of a particular geometry of the depressions, especially having Mo3726 Le A 28 195-US!CA
2~0~6~ ~
a sufficient depth, the adhesion can be optirnized. Since the material cured in the depressions has a certain elasticity, when released by the cleaning piston it bulges into the mixing chamber bore. The bulge is only of a few tenths of a millimeter. On the next ejection stroke of the cleaning piston, the front edge of the piston not only scrapes off this protruding bulge, but also drags out some of the material from the grooves, or depressions, due to the elasticity of the material. Simultaneously in the ejection stroke, the film of mixture present in the sliding clearance is stripped off into the freshly produced cavities in the material of the depressions. This new material cures and again bulges into the mixing chamber bore during the return of ejector piston into its mixing position, which corresponds the rear dead point, and so on.
The new embodiment is especially favorable since the edges surrounding the grooves, or depressions, function as stripping edges. Differently shaped depressions, such as for example troughs, are also possible. It is important in this connection only that the depressions be at least tangential to each other in the circumferential direction of the mixing chamber bore.
It is preferred that they overlap, in order that stripping of the film of mixture is possible over the whole circumference.
Nevertheless the depressions must necessarily be interrupted in the area of the injection openings in order that there be sufficient wall around the injection openings. The depth, a, and the width, b, of the annular grooves as well as the thickness, c, of the lands (i.e, the area surrounding the grooves) naturally depend on the diameter of the cleaning piston and the diameter of the mixing chamber bore. The greater is this diameter the greater are the dimensions of the annular grooves and lands.
Even if the annular grooves disclosed in U.S. patent 3,799,199 at the upper and lower ends of the cleaning piston were moved to the wall of the mixing chamber bore, the Mo3726 Le A 28 195-US/CA
2~ 6~
surprising new effect would not be achieved since the film of mixture would not be adequately stripped off.
Good results can be achieved if the annular grooves have a depth, a, of 0.5 to 3 mm at a width, b, of 1 to 4 mm, and the lands remaining have a thickness, c, of 2 to 8 mm.
The new mix head is shown purely diagrammatically in section in the drawing and explained in more detail below. A
hydraulically operated cleaning piston 2, driven in a mlxing chamber bore 3, is disposed in the body 1 of the mix head.
Injection openings 4, 5 discharge into the mixing chamber bore 3. Depressions 7, in the form of annular grooves in the wall 6 of the mixing chamber bore 3, alternate with lands 8 over the whole length of the mixing chamber bore. The diameter of the mixing chamber bore 3 is 20 mm, the depth, a, of the annular grooves 7 is 3 mm, their width, b, is 2 mm and the thickness, c, of the lands 8 is 6 mm.
In Figure 2, the annular grooves 7 are filled with cured material 9 which because of its elasticity presses against the cleaning piston 2.
In Figure 3, the material 9 present in the annular grooves 7, due to its elastic expansion, forms bulges in the mixing chamber bore 3, since the cleaning piston 2 returned.
After a few mixing operations, the depressions 7 have become filled with cured reaction mixture, which adheres firmly therein and forms an elastic mass. Reaction components are, for example, polyol and isocyanate, which cure to form a polyurethane.
The cleaning piston 2 returns from the cleaning position into the mixing position and clears the injection openings 4 and 5 for the injection of the reaction components. ~he material 9 present in the annular grooves 7 bulges slightly, because of elasticity, over the wall 6 into the mixing chamber bore 3. After completion of the mixing operation, the cleaning piston 2 again moves into the cleaning position, then ejects remaining reaction mixture and scrapes off the projecting Mo3726 Le A 28 195-US/CA
bulges 10, whereby simultaneously some material is also torn out of the depressions 7, so that small cavities are formed.
When the cleaning piston 2 returns, the film of mixture present in the sliding clearance is stripped off into these cavities.
This new material compacts there. During the next stroke of the cleaning piston 2 into the mixing position, the bulges 10 mentioned are formed. The process repeats itself during each cycle.
Although the ;nvention has been described in detail in the lo foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
Mo3726 Le A 28 195-US/CA
Good results can be achieved if the annular grooves have a depth, a, of 0.5 to 3 mm at a width, b, of 1 to 4 mm, and the lands remaining have a thickness, c, of 2 to 8 mm.
The new mix head is shown purely diagrammatically in section in the drawing and explained in more detail below. A
hydraulically operated cleaning piston 2, driven in a mlxing chamber bore 3, is disposed in the body 1 of the mix head.
Injection openings 4, 5 discharge into the mixing chamber bore 3. Depressions 7, in the form of annular grooves in the wall 6 of the mixing chamber bore 3, alternate with lands 8 over the whole length of the mixing chamber bore. The diameter of the mixing chamber bore 3 is 20 mm, the depth, a, of the annular grooves 7 is 3 mm, their width, b, is 2 mm and the thickness, c, of the lands 8 is 6 mm.
In Figure 2, the annular grooves 7 are filled with cured material 9 which because of its elasticity presses against the cleaning piston 2.
In Figure 3, the material 9 present in the annular grooves 7, due to its elastic expansion, forms bulges in the mixing chamber bore 3, since the cleaning piston 2 returned.
After a few mixing operations, the depressions 7 have become filled with cured reaction mixture, which adheres firmly therein and forms an elastic mass. Reaction components are, for example, polyol and isocyanate, which cure to form a polyurethane.
The cleaning piston 2 returns from the cleaning position into the mixing position and clears the injection openings 4 and 5 for the injection of the reaction components. ~he material 9 present in the annular grooves 7 bulges slightly, because of elasticity, over the wall 6 into the mixing chamber bore 3. After completion of the mixing operation, the cleaning piston 2 again moves into the cleaning position, then ejects remaining reaction mixture and scrapes off the projecting Mo3726 Le A 28 195-US/CA
bulges 10, whereby simultaneously some material is also torn out of the depressions 7, so that small cavities are formed.
When the cleaning piston 2 returns, the film of mixture present in the sliding clearance is stripped off into these cavities.
This new material compacts there. During the next stroke of the cleaning piston 2 into the mixing position, the bulges 10 mentioned are formed. The process repeats itself during each cycle.
Although the ;nvention has been described in detail in the lo foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
Mo3726 Le A 28 195-US/CA
Claims (2)
1. A mix head for the production of a flowable reaction mixture comprising a body with a mixing chamber bore in which a cleaning piston is driven and into which injection reaction components discharge, and wherein the walls of said bore are provided with depressions, wherein said depressions are annular grooves are arranged over the whole length of the mixing chamber bore in its wall, at right angles to the axis of the mixing chamber bore.
2. The mix head of Claim 1 wherein the annular grooves have a depth of 0.5 to 3 mm at a width b of 1 to 4 mm.
Mo3726 Le A 28 195-US/CA
Mo3726 Le A 28 195-US/CA
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4103711.1 | 1991-02-07 | ||
| DE4103711A DE4103711C1 (en) | 1991-02-07 | 1991-02-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2060566A1 true CA2060566A1 (en) | 1992-08-08 |
Family
ID=6424571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002060566A Abandoned CA2060566A1 (en) | 1991-02-07 | 1992-02-03 | Mix head for the production of a flowable reaction mixture |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0498244A1 (en) |
| JP (1) | JPH04336209A (en) |
| CA (1) | CA2060566A1 (en) |
| DE (1) | DE4103711C1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5785422A (en) * | 1995-04-24 | 1998-07-28 | Krauss-Maffei Ag | Piston arrangement for removing a reactive plastic mixture from a stabilizing chamber of a mixing device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE779971R (en) * | 1971-04-10 | 1972-06-16 | Krauss Maffei Ag | APPARATUS FOR PRIMING AND PREPARING A MIXTURE OF TWO OR SEVERAL SYNTHETIC CONSTITUENTS IN THE MOLDING CAVITY OF A |
| DE2838798B2 (en) * | 1978-09-06 | 1980-07-10 | Elastogran Maschinenbau Gmbh & Co, 8021 Strasslach | Mixing device for liquid components that react chemically with one another, preferably forming polyurethane |
| US4377256A (en) * | 1981-06-22 | 1983-03-22 | Gusmer Corporation | Apparatus for dispensing a mixture of mutually reactive liquids |
| DE8214997U1 (en) * | 1982-05-22 | 1982-09-16 | Elastogran Maschinenbau GmbH, 2844 Lemförde | CONTROL UNIT FOR A MIXING DEVICE FOR PLASTIC COMPONENTS |
| DE8912468U1 (en) * | 1989-10-20 | 1989-11-30 | Hellberg, Werner, Dipl.-Ing., 2072 Jersbek | Two-component needle mixing gun |
-
1991
- 1991-02-07 DE DE4103711A patent/DE4103711C1/de not_active Expired - Lifetime
-
1992
- 1992-01-27 EP EP92101232A patent/EP0498244A1/en not_active Withdrawn
- 1992-02-03 CA CA002060566A patent/CA2060566A1/en not_active Abandoned
- 1992-02-05 JP JP4047696A patent/JPH04336209A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5785422A (en) * | 1995-04-24 | 1998-07-28 | Krauss-Maffei Ag | Piston arrangement for removing a reactive plastic mixture from a stabilizing chamber of a mixing device |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0498244A1 (en) | 1992-08-12 |
| DE4103711C1 (en) | 1992-07-30 |
| JPH04336209A (en) | 1992-11-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |