CA1059775A - Corrogated drainpipe and method of manufacturing same - Google Patents
Corrogated drainpipe and method of manufacturing sameInfo
- Publication number
- CA1059775A CA1059775A CA258,603A CA258603A CA1059775A CA 1059775 A CA1059775 A CA 1059775A CA 258603 A CA258603 A CA 258603A CA 1059775 A CA1059775 A CA 1059775A
- Authority
- CA
- Canada
- Prior art keywords
- drainpipe
- sheet
- polymeric material
- film
- corrogated
- 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.)
- Expired
Links
Landscapes
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Shaping Of Tube Ends By Bending Or Straightening (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A drainpipe is disclosed which is preferably formed from a number of juxtaposed sheets made of polymeric material and arranged in a generally tubular formation with adjacent edges unbonded. The sheets are reinforced and held in place by one or more helical structures made of polymeric material and adhesively joined to the sheets.
A drainpipe is disclosed which is preferably formed from a number of juxtaposed sheets made of polymeric material and arranged in a generally tubular formation with adjacent edges unbonded. The sheets are reinforced and held in place by one or more helical structures made of polymeric material and adhesively joined to the sheets.
Description
~L~5~7~
Drainpipes are usually produced in a corrugated shaps in order to improve the stiffness in proportion to weight. The corrugations are formed in a kind of continuous blow-molding process or the like. The necessary porosity is produced by cutting, grinding, or impressing holes in the pipe after solidifcation.
A draw-back of such pipes is that the internal surface will also be corrugated and thereby promote choking of the pipe by solid items.
An object of the present invention is to provide for a drainpipe which is corrugated on the external surface but smooth at the internal surface, and a second object is to provide for an improved system to form the porosity of the pipe, both objects considered in relation with the simplicity of manufacturing the structure.
The drainpipe according to the invention comprises one or a number of juxtaposed sheets comprising polymer material, arranged to form a generally tubular shape or array with ad;acent edges generally unbonded to one another, the sheet(s) being reinforced and held in shape by one or more helical structures comprising the same or a diEferent polymer material and adhesively joined with the sheet~s).
The invention will now be described with reference to a presently preferred embodiment which is shown in the attached drawing wherein:
Figure 1 is a perspective view of a corrugated drainpipe according to the invention.
Figure 2 is a perspective view with partial sections, which in schematical manner shows a rotary extrusion device suitable for making the drainpipe of Figure 1, and Figure 3, also in perspective view, shows further details of the inner rotary part (12) of the abovementioned die.
In Figure 1, a preformed thermoplastic film or sheet (1) has been bent to tubular shape over a mandrel. There is left an open gap (2) of a si~e suitable for drainage. Using an extrusion process, four thick filaments (3), - .~
~L~S~775 (4), (5) and (6) have been wound in spiral manner around the tubular film or sheet (1) and bonded to the latter either by direct fusion or by any suitable adhesive means. In order to achieve high stiffness of the filaments in proportion to their weight, they are preferably made with a cellular structure, achieved by use of a blowing agent in the extrusion proceSs.
From observation of Figure 1, it will be understood that this principal construction of a pipe is suitable for achieving high cushion resistance combined with bendability in respect of the tube axis (7). It will also be understood that this construction avoids corrugation of the inner surface of the pipe, such corrugation otherwise occuring in all known constructions of corrugated drainpipes. The present drainpipe, therefore, minimizes the tendency to blocking of the pipe by "hang-up" of solid particles.
In Figure 2, (8) is the mandrel over which the film or sheet ~l) is bent to tubular shape. The mandrel ends at (9). The support for the mandrel is not shown. Film or sheet (1) can either be taken from a reel, or can be formed by extrusion and/or calendering immediately prior to the process shown in the drawing.
The advancing of the film or sheet (l) and of the final product formed therefrom, takes place by means of two conveyor belts (lO) and (11) (or the like). The devices for guiding the film (1) onto the mandrel~ and the heating means for softening the film or sheet before bending it, are not shown.
The extrusion device by means of which the filaments (3), (4), (5) and (6) are formed and spirally wound around the tube, is a desk extruder of special construction. It comprises an inner, circular, rotatable part (12), an outer circular, rotatable part (13) and a fixed circular insert (14) provided with vanes (lS~. Bearings, driving means, heating elements and temperature control means are not shown since they form no part of the present invention ana tney are in any event fully dealt with in my copending Canadian application ; J
l -2-~L~S~775 serial No. 245,593, filed February 12, 1976. The insert (14) is assembled of two or more parts, each kept in fixed position by one or more supports, indicated by (16) in the drawings (Fig. 2).
From an outlet (17) of an ordinary extruder, molten polymer which contains of a blowing agent is extruded without pressure into the groove (18) formed by and between the two rotatable extruder parts (12) and (13). The rotation of these parts, in cooperation with the fixed insert (14) supplied with vanes (15), produces a pumping action which is directed inwardly. While the outer extruder part (13) has a plane conical surface on the side forming the passageway for the polymer, the corresponding surface of the inner extruder part (12), as best seen in Fig. 3, has four partitions (19) made to break up the circular polymer stream into four part streams which are gradually constrained to filament shape and extruded as filaments from the exit orifices (20), (21), (22) and (23) (Fig. 3).
The speed of rotation of the inner extruder part (12) defining the exit orifices 20 to 23, in relation to the speed of advance of the pipe, determines the pitch of the wound filaments, while the weight of extruded filament material per hour depends on the speeds of rotation of both extruder parts (12) and (13). These parts may be rotated at different velocities. The pres5ureless feed of molten polymer to the desk extruder must conform herewith, but within certain limitS, depend on the construction of the desk extruder, there is a self-controlling effect caused by the fact that a higher filling of the groove (18) results in a higher pumping effect.
While the drawings show four thick filaments wound around the tubular film or sheet, this number is of course not critical but can be higher or lower, including the possibility of using only one filament.
The invention will be further illustrated with reference to a specific example.
EXAMPLE
The die of Figure 3 in my aforementioned Canadian copending application No. 245,593, filed February 12, 1976 should be used, however 59t77S
ending in one, two, or some other small number of exit orifices of about Smm diameter. Polyethy~ene of density 0.96 and melt index 0.2 (ASTM) can conveniently be used for this extrusion which is a melt-extrusion carried out e.g. at 200 C.
As conveying and support means should be used a fixed mandrel and . a pre-formed film, generally as shown in Figure 4 of my said application serial No. 245,593. However, when the pre-formed film (ribbon) is folded around the mandrel, a gap of about 1 mm should be maintained between the edges instead of bringing the latter to overlap. The purpose of this gap is to make the final pipe permeable. This film, which is intended to form the inner surface of the pipe, conveniently consists of the same material as the polymer fed to the rotatable die.
The rotations should be adjusted to wind the two (or more) coarse filaments around the conveyor film in form of a double spiral (thread) with a few millimeters pitch. A suitable temperature of the mandrel at the zone of collection will be about 100 C so as to allow the extruded double thread to fuse together with the conveyor film. A suitable thickness of the latter will be about 0.5 mm. Direct water-cooling should be applied on the pipe immediately after the collection.
The structure can of course be modified by arranging two or more ribbons instead of only one ribbon around the mandrel with a small gap between each pair of adjacent edges.
The structure can be modified and improved in various manners.
Thus the helical reinfor~ement structure(s) can conveniently consist of expandable polymer which is expanded while it is extruded and wound onto the sheet(s) in semi-fluid to fluid state.
Further, there can conveniently be interposed a filter material such as e.g. a woven or non-woven cloth or a porous sheet material between on one side adjacent edge portions of the sheet(s) and on the other side the helical structure(s).
i -4-
Drainpipes are usually produced in a corrugated shaps in order to improve the stiffness in proportion to weight. The corrugations are formed in a kind of continuous blow-molding process or the like. The necessary porosity is produced by cutting, grinding, or impressing holes in the pipe after solidifcation.
A draw-back of such pipes is that the internal surface will also be corrugated and thereby promote choking of the pipe by solid items.
An object of the present invention is to provide for a drainpipe which is corrugated on the external surface but smooth at the internal surface, and a second object is to provide for an improved system to form the porosity of the pipe, both objects considered in relation with the simplicity of manufacturing the structure.
The drainpipe according to the invention comprises one or a number of juxtaposed sheets comprising polymer material, arranged to form a generally tubular shape or array with ad;acent edges generally unbonded to one another, the sheet(s) being reinforced and held in shape by one or more helical structures comprising the same or a diEferent polymer material and adhesively joined with the sheet~s).
The invention will now be described with reference to a presently preferred embodiment which is shown in the attached drawing wherein:
Figure 1 is a perspective view of a corrugated drainpipe according to the invention.
Figure 2 is a perspective view with partial sections, which in schematical manner shows a rotary extrusion device suitable for making the drainpipe of Figure 1, and Figure 3, also in perspective view, shows further details of the inner rotary part (12) of the abovementioned die.
In Figure 1, a preformed thermoplastic film or sheet (1) has been bent to tubular shape over a mandrel. There is left an open gap (2) of a si~e suitable for drainage. Using an extrusion process, four thick filaments (3), - .~
~L~S~775 (4), (5) and (6) have been wound in spiral manner around the tubular film or sheet (1) and bonded to the latter either by direct fusion or by any suitable adhesive means. In order to achieve high stiffness of the filaments in proportion to their weight, they are preferably made with a cellular structure, achieved by use of a blowing agent in the extrusion proceSs.
From observation of Figure 1, it will be understood that this principal construction of a pipe is suitable for achieving high cushion resistance combined with bendability in respect of the tube axis (7). It will also be understood that this construction avoids corrugation of the inner surface of the pipe, such corrugation otherwise occuring in all known constructions of corrugated drainpipes. The present drainpipe, therefore, minimizes the tendency to blocking of the pipe by "hang-up" of solid particles.
In Figure 2, (8) is the mandrel over which the film or sheet ~l) is bent to tubular shape. The mandrel ends at (9). The support for the mandrel is not shown. Film or sheet (1) can either be taken from a reel, or can be formed by extrusion and/or calendering immediately prior to the process shown in the drawing.
The advancing of the film or sheet (l) and of the final product formed therefrom, takes place by means of two conveyor belts (lO) and (11) (or the like). The devices for guiding the film (1) onto the mandrel~ and the heating means for softening the film or sheet before bending it, are not shown.
The extrusion device by means of which the filaments (3), (4), (5) and (6) are formed and spirally wound around the tube, is a desk extruder of special construction. It comprises an inner, circular, rotatable part (12), an outer circular, rotatable part (13) and a fixed circular insert (14) provided with vanes (lS~. Bearings, driving means, heating elements and temperature control means are not shown since they form no part of the present invention ana tney are in any event fully dealt with in my copending Canadian application ; J
l -2-~L~S~775 serial No. 245,593, filed February 12, 1976. The insert (14) is assembled of two or more parts, each kept in fixed position by one or more supports, indicated by (16) in the drawings (Fig. 2).
From an outlet (17) of an ordinary extruder, molten polymer which contains of a blowing agent is extruded without pressure into the groove (18) formed by and between the two rotatable extruder parts (12) and (13). The rotation of these parts, in cooperation with the fixed insert (14) supplied with vanes (15), produces a pumping action which is directed inwardly. While the outer extruder part (13) has a plane conical surface on the side forming the passageway for the polymer, the corresponding surface of the inner extruder part (12), as best seen in Fig. 3, has four partitions (19) made to break up the circular polymer stream into four part streams which are gradually constrained to filament shape and extruded as filaments from the exit orifices (20), (21), (22) and (23) (Fig. 3).
The speed of rotation of the inner extruder part (12) defining the exit orifices 20 to 23, in relation to the speed of advance of the pipe, determines the pitch of the wound filaments, while the weight of extruded filament material per hour depends on the speeds of rotation of both extruder parts (12) and (13). These parts may be rotated at different velocities. The pres5ureless feed of molten polymer to the desk extruder must conform herewith, but within certain limitS, depend on the construction of the desk extruder, there is a self-controlling effect caused by the fact that a higher filling of the groove (18) results in a higher pumping effect.
While the drawings show four thick filaments wound around the tubular film or sheet, this number is of course not critical but can be higher or lower, including the possibility of using only one filament.
The invention will be further illustrated with reference to a specific example.
EXAMPLE
The die of Figure 3 in my aforementioned Canadian copending application No. 245,593, filed February 12, 1976 should be used, however 59t77S
ending in one, two, or some other small number of exit orifices of about Smm diameter. Polyethy~ene of density 0.96 and melt index 0.2 (ASTM) can conveniently be used for this extrusion which is a melt-extrusion carried out e.g. at 200 C.
As conveying and support means should be used a fixed mandrel and . a pre-formed film, generally as shown in Figure 4 of my said application serial No. 245,593. However, when the pre-formed film (ribbon) is folded around the mandrel, a gap of about 1 mm should be maintained between the edges instead of bringing the latter to overlap. The purpose of this gap is to make the final pipe permeable. This film, which is intended to form the inner surface of the pipe, conveniently consists of the same material as the polymer fed to the rotatable die.
The rotations should be adjusted to wind the two (or more) coarse filaments around the conveyor film in form of a double spiral (thread) with a few millimeters pitch. A suitable temperature of the mandrel at the zone of collection will be about 100 C so as to allow the extruded double thread to fuse together with the conveyor film. A suitable thickness of the latter will be about 0.5 mm. Direct water-cooling should be applied on the pipe immediately after the collection.
The structure can of course be modified by arranging two or more ribbons instead of only one ribbon around the mandrel with a small gap between each pair of adjacent edges.
The structure can be modified and improved in various manners.
Thus the helical reinfor~ement structure(s) can conveniently consist of expandable polymer which is expanded while it is extruded and wound onto the sheet(s) in semi-fluid to fluid state.
Further, there can conveniently be interposed a filter material such as e.g. a woven or non-woven cloth or a porous sheet material between on one side adjacent edge portions of the sheet(s) and on the other side the helical structure(s).
i -4-
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A drainpipe comprising one or a number of juxtaposed sheets comprising polymeric material, arranged to form a generally tubular shape or array with adjacent edges slightly spaced apart from one another, the sheet(s) being reinforced and held in place by one or more helical structures comprising the same or a different polymeric material bonded to the sheet(s).
2. A drainpipe according to claim 1, in which a filter material is interposed between on one side adjacent edge portions of the sheet(s) and on the other side the helical structure(s).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA258,603A CA1059775A (en) | 1976-08-06 | 1976-08-06 | Corrogated drainpipe and method of manufacturing same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA258,603A CA1059775A (en) | 1976-08-06 | 1976-08-06 | Corrogated drainpipe and method of manufacturing same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1059775A true CA1059775A (en) | 1979-08-07 |
Family
ID=4106602
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA258,603A Expired CA1059775A (en) | 1976-08-06 | 1976-08-06 | Corrogated drainpipe and method of manufacturing same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1059775A (en) |
-
1976
- 1976-08-06 CA CA258,603A patent/CA1059775A/en not_active Expired
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