Plastic article or earthenware shaping or treating: apparatus – With means applying coating material to work or work contact... – Separate means applying material directly to shaping means,...
Patent
1985-05-08
1986-05-27
Hoag, Willard E.
Plastic article or earthenware shaping or treating: apparatus
With means applying coating material to work or work contact...
Separate means applying material directly to shaping means,...
4253261, 425376R, 425380, 425392, B29C 4794, B29C 4790, B29D 2318
Patent
active
045913234
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an extruder assembly for extruding round, cylindrical plastic pipe having a smooth inner wall and a rigid outer wall surface.
It has long been realized that pipes having external ribs or ridges offer great advantages over smooth-walled pipes for applications in which the pipe is subjected to radial loading. Such loads may arise from internal fluid pressure or external ground pressure. The ribs provide the pipe with high annular strength in relation to weight, and permit a savings of material when producing the pipe.
Corrugated pipes, e.g., pipes having both internal and external ridges, have long been produced for different purposes. Such pipes have high annular strength in relation to their weight, but they are not suited for use as conduits for water supply or waste discharge because the pipe's flow resistance is too high. Such pipes have been used as electrical conduit pipes and drainage pipes. Corrugated pipes have, however, been utilized to some extent for producing pipes of the type defined above, using a second extruder to produce a smooth pipe and inserting this within the corrugated pipe, welding the two together in a common tool complex. Pipes having a smooth inside wall and a ridged outer surface have also been produced by cutting ridges or ribs in the outer wall of a smooth pipe. Both of these methods are expensive, and are only suited only for certain types of plastic.
British Pat. No. 618.536 discloses a method for producing plastic piping having a smooth inner wall and a ridged outer surface in which the ribs follow a helical path. According to the patent specification, this pipe is produced directly from only one extruder, the extruder's mandrel being an extention of its Archimedean screw and being provided with external ribs that follow a helical path. The theory is that the rotating mandrel shall impart a rotary motion to the plastic material exiting from the extruder nozzle. The external molding tool is provided with grooves that follow a helical path. This patent was applied for as early as 1944, at the very beginning of modern plastics technology, but no one has yet managed to actually produce a plastic pipe having a ribbed outer surface and a smooth inner wall directly from a single extruder.
The main object of the invention, based on the above prior art, is to provide a plastics extruder with which one can directly and continuously produced a plastic pipe having a smooth inner wall and a ribbed outer wall surface.
One of the major problems with such productions is associated with the lubrication of the annular nozzle's stationary outer mold section. Both the amount of lubricant and the continuity of its application are relatively critical factors. If too little lubricant is supplied, the adhesion between the plastic material and the wall of the mold will be too high and the plastic will stick to the mold wall, resulting in an interruption of the production process. If too much lubricant is supplied, the excess lubricant will become intermixed with the plastic material, and the quality of the outer pipe surface will be unacceptable. This may also cause interrupted production.
A particular object of the invention, therefore, is to ensure satisfactory lubrication of the internal wall of the stationary, outer section of the mold, thereby enabling continuous production of plastic pipes of good quality.
In any extrusion of plastic profiles, e.g., plastic pipe, the extruded profile must pass through a calibrating device to ensure that the product's dimensions are stable and that it is a acceptable quality. In the case of extruded pipes, the pipe is guided through a sleeve whose internal dimensions correspond exactly to the outside dimensions of the finished pipe. To obtain firm contact between the outer pipe wall and the internal sleeve wall, one can either introduce compressed air into the pipe, or the pipe wall can be drawn out toward the sleeve wall by means of vacuum introduced through small apertures in the sleeve wall.
Experiments have shown that neith
REFERENCES:
patent: 2443289 (1948-06-01), Bailey
patent: 2512844 (1950-06-01), Weber
patent: 2688153 (1954-09-01), Gebauer et al.
patent: 2743511 (1956-05-01), Genovese
patent: 3212154 (1965-10-01), Crumpler
patent: 3221805 (1966-05-01), Given
patent: 3244781 (1966-04-01), Covington et al.
patent: 3577935 (1971-05-01), Reinhart
patent: 3659987 (1972-05-01), Mixell et al.
patent: 3666389 (1972-05-01), Nelson
patent: 3685147 (1972-08-01), Nevin et al.
patent: 3711232 (1973-01-01), Van Zon
patent: 3844700 (1974-10-01), Sokolow
patent: 4017244 (1977-04-01), Vellani
patent: 4053274 (1977-10-01), Lemelson
patent: 4077758 (1978-03-01), de Putter
patent: 4087222 (1978-05-01), Noel
patent: 4091064 (1978-05-01), Kakinuma et al.
patent: 4181486 (1980-01-01), Saito
patent: 4548567 (1985-10-01), Missout
A/S Sonnichsen Rorvalseverket
Hoag Willard E.
LandOfFree
Extruder and calibrating apparatus for making ribbed or grooved does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Extruder and calibrating apparatus for making ribbed or grooved , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Extruder and calibrating apparatus for making ribbed or grooved will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1569470