Triwall siding apparatus

• US 4,911,628 A
• Filed: 10/05/1988
• Issued: 03/27/1990
• Est. Priority Date: 10/05/1988
• Status: Expired due to Term

• Current Assignee: National Canada Finance Corp.
• Original Assignee: American Maplan Corp. (BC Extrusion Holding GmbH)
• Inventors: Heilmayr, Peter, Gearhart, Kenton, Hawkes, Cliff
• Primary Examiner(s): Thurlow, Jeffery
• Application Number:
  US07/254,385
• Time in Patent Office: 538 Days
• Field of Search: 264/171, 264/177.1, 264/177.16, 264/45.9, 425/131.1, 425/4 C, 425/133.5, 425/817 C
• US Class Current: 425/131.1
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/307 specially adapted for bringing together components, e.g. melts within the die
• CPC Class Codes: B29C 48/495 Feed-blocks extrusion moulding of multi-component articles B29C48/16

Abstract

Highly uniform three-layer extrusions generally of flat siding or panels, preferably of PVC are extruded in an apparatus having a flow block in which lateral extruders supply the upper and lower layer streams to respective curved flow passages running to outlets of a flow block while a main extruder supplies the foam PVC to the central outlet. The outlets are aligned with orifices of a flow plate connected by respective channels to outlet orifices arranged within a common circle and communicating with a die. The outlet orifices include a pair of elongated kidney-shaped orifices encircling and straddling an ovoid central orifice.

Claims

1. An apparatus for extruding a continuous generally flat extrusion having three layers of synthetic resin material, comprising:

a flow block having a main axis and a pair of axial ends, said flow block being formed with a main-flow inlet at one of said axial ends, a main-flow outlet axially aligned with said main-flow inlet at the other of said axial ends, a pair of lateral inlets disposed on opposite sides of a median plane along said main axis and having respective inlet axes including angles between about 45° and

about 85°

with said plane and vertices tapering in a direction toward said other end, a pair of additional outlets at said other axial end having outlet axes parallel to said main axis and flanking said main-flow outlet, a substantially rectilinear main-flow passage extending along said main-flow axis and connecting said main-flow inlet with said main-flow outlet, and respective additional passages interconnecting each of said lateral inlets with a respective one of said additional outlets and substantially continuously curved therebetween;

respective adapters connecting each of said inlets to a respective extruder for delivering respective streams of thermoplastic synthetic resin to said passages and the respective outlets;

a positive displacement flow plate adjacent said other axial end of said flow block, said flow plate being formed on one side with a first planar end face provided with a circular central-inlet orifice registering with said main flow outlet and additional circular inlet orifices respectively registering with said additional outlets, said flow plate being formed on an opposite side with a second planar end face parallel to the first planar end face and provided with a central-outlet orifice of generally ovoid configuration, and with additional outlet orifices of generally elongated arcuate kidney shape extending arcuately around and straddling said central-outlet orifice, said flow plate being further formed with respective channels smoothly connecting each of said additional inlet orifices with a respective one of said additional outlet orifices and said central-inlet orifice with said central-outlet orifice; and

a die having a circular inlet registering with all of said outlet orifices, a wide mouth from which a flat workpiece consisting of said streams in respective layers emerges, and a passage spreading from said circular inlet of the die to said mouth, each of said additional outlet orifices having an outer margin centered on a common circle and disposed diametrically opposite one another across said circle, said outlet orifices being symmetrical with respect to a plane of symmetry including centers of said inlet orifices and said common circle.

2. The apparatus defined in claim 1 wherein each of said additional outlet orifices has rounded ends terminating substantially at a plane through said center of said common circle and perpendicular to said plane of symmetry.

5. The apparatus defined in claim 1 wherein said flow plate is sandwiched between an adapter connected with said die and said flow block.

3. A positive displacement flow plate for use between a flow block having a plurality of outlets for respective streams of synthetic resin material and an extrusion die, said flow plate comprising a body formed on one side with a first planar end face provided with a circular central-inlet orifice registering with one of said outlets and additional inlet orifices respectively registering with additional ones of said outlets, said body being formed on an opposite side with a second planar end face parallel to the first planar end face and provided with a central-outlet orifice of generally ovoid configuration, and with additional outlet orifices of generally elongated arcuate kidney shape extending arcuately around and straddling said central-outlet orifice, said body being further formed with respective channels smoothly connecting each of said additional inlet orifices with a respective one of said additional outlet orifices and said central-inlet orifice with said central-outlet orifice, whereby said die can communicate with said outlet orifices, each of said additional outlet orifices having an outer margin centered on a common circle and disposed diametrically opposite one another across said circle, said outlet orifices having symmetrical with respect to a plane of symmetry including centers of said inlet orifices and said common circle.

4. A flow plate defined in claim 3 wherein each of said additional outlet orifices has rounded ends terminating substantially at a plane through said center of said common circle and perpendicular to said plane of symmetry.