Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
230 words
An apparatus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of said die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one said chill from each said set of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular section, the improvement wherein the said chills and smoothing mandrel defining a minimum average tubular section wall thickness, and the radius of the circular cross section of said grooves of said chills being substantially smaller than the radius of the circular cross section of the ribs thereby reducing the weight of the resulting tubular section for a given level of mechanical property.
Claim 2
Independent Claim
230 words
An apparatus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of said die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one said chill from each said set of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular section, the improvement wherein the said chills and smoothing mandrel defining a minimum average tubular section wall thickness, and the radius of the circular cross section of said grooves of said chills being substantially smaller than the radius of the circular cross section of the ribs thereby reducing the weight of the resulting tubular section for a given level of mechanical property.
Claim 3
Independent Claim
271 words
An apparatus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of said die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one said chill from each said set of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular seciton, the improvement comprising the radius of the circular cross section of said grooves of a said chill being smaller than the radius of the circular cross section of said ribs of the said chill, racks being provided on backs of each said chills, wherein said conveyer means comprise for the rectilinear forward branch of their closed loop paths gears adapted to mesh with said racks of said chills, and controlled rotation means coupled for rotation with said gears for modulating the resultant advance speed of said chills about an average speed thereby compensating for the variable cross section of said casting cavity.
Claim 4
Independent Claim
271 words
An apparatus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of said die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one said chill from each said set of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular seciton, the improvement comprising the radius of the circular cross section of said grooves of a said chill being smaller than the radius of the circular cross section of said ribs of the said chill, racks being provided on backs of each said chills, wherein said conveyer means comprise for the rectilinear forward branch of their closed loop paths gears adapted to mesh with said racks of said chills, and controlled rotation means coupled for rotation with said gears for modulating the resultant advance speed of said chills about an average speed thereby compensating for the variable cross section of said casting cavity.
Claim 5
Dependent Claim
212 words
An appartus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of said die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one of said chill from each of said sets of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular section, the radius of the circular cross section of said grooves of a said chill being smaller than the radius of the circular cross section of said ribs of the said chill, and a fixed guide meshing with said chills in succession.
Claim 6
Dependent Claim
212 words
An appartus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of said die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one of said chill from each of said sets of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular section, the radius of the circular cross section of said grooves of a said chill being smaller than the radius of the circular cross section of said ribs of the said chill, and a fixed guide meshing with said chills in succession.
Claim 7
Independent Claim
220 words
An apparatus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of aid die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one said chill from each said set of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular section, the improvement wherein said chills defining a minimum average tubular section wall thickness, and the cross sectional area of said grooves of said chills being substantially smaller than the cross section area of said ribs thereby reducing the weight of the resulting tubular section for a given level of mechanical properties.
Claim 8
Independent Claim
220 words
An apparatus for continuous extrusion of tubular sections of thermoplastic material, the tubular section having a smooth inner surface and an annularly finned outer surface, said apparatus comprising a tubular extrusion die assembly having an axis formed by an outer die part and an inner die plunger in combination with two sets of chills each defining a casting cavity position, said chill having grooves of circular cross section alternating with ribs also of circular cross section thereby defining annular fins, conveyer means, for each said set of chills, for continuous displacement thereof along closed loop paths comprising a rectilinear forward branch extending parallel to the axis of aid die assembly and on each side of an outlet opening of said die assembly, pairs of chills formed by one said chill from each said set of chills defining successive casting rings, a smoothing mandrel in line with said die plunger of said die assembly, said smoothing mandrel and said chills together defining said casting cavity for the desired tubular section, the improvement wherein said chills defining a minimum average tubular section wall thickness, and the cross sectional area of said grooves of said chills being substantially smaller than the cross section area of said ribs thereby reducing the weight of the resulting tubular section for a given level of mechanical properties.
Claim 9
Dependent Claim
32 words
An apparatus as claimed in claim 1, 3, or 4, said conveyer means providing advance speed modulation about an average speed for compensating for the variable cross section of said casting cavity.
Claim 10
Dependent Claim
29 words
An apparatus as claimed in claim 3, said fixed guide comprising at least one rail, wherein each of said chills comprises a longitudinal groove for engagement with said rail.
Claim 11
Dependent Claim
68 words
An apparatus as claimed in claim 3, racks being provided on backs of each said chills, said conveyer means comprising for the rectilinear forward branch of their closed loop paths gears adapted to mesh with said racks, of said chills, said gears comprising a drive gear at the incoming end of said fixed guide and further comprising a braking gear at the outlet end of said fixed guide.
Claim 12
Dependent Claim
75 words
An apparatus as claimed in claim 1, 2 or 3, means for cooling said smoothing mandrel over at least part of its length comprising channels in said smoothing mandrel for the circulation of cooling fluid therein, wherein at least one portion of said smoothing mandrel is at least locally porous for the flow of cooling fluid, an inner face of said one portion being in communication with said channels for the flow of cooling fluid.
Claim 13
Dependent Claim
37 words
An apparatus as claimed in claim 1, 2 or 3, further comprising means for cooling said smoothing mandrel over its terminal part only including channels in said smoothing mandrel for the flow of a cooling fluid therein.
Claim 14
Dependent Claim
37 words
An apparatus as claimed in claim 1, 2 or 3, said smoothing mandrel being externally truncated with its outer diameter decreasing over at least the distance of its length between said die plunger and its free end.
Claim 15
Dependent Claim
41 words
An apparatus as claimed in claim 1, in which the radius of said circular cross section of said ribs of the said chill ranges from 1.1-1.8 times the radius of the circular cross section of the grooves of the said chill.
Claim 16
Dependent Claim
41 words
An apparatus as claimed in claim 1, in which the radius of said circular cross section of said ribs of the said chill ranges from 1.25-1.35 times the radius of the circular cross section of said grooves of the said chill.