CA1095211A

CA1095211A - Processing extruded thermoplastic polymer

Info

Publication number: CA1095211A
Application number: CA297,834A
Authority: CA
Inventors: Joachim E. Hartitz
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1977-04-06
Filing date: 1978-02-24
Publication date: 1981-02-10
Also published as: IT7821881A0; DE2811450A1; AU3375078A; FR2386408A1; SE7803238L; US4115495A; JPS53125468A; NL7803519A; BE865761A; IT1094034B

Abstract

Attorney's File No. 1770029 PROCESSING EXTRUDED THERMOPLASTIC POLYMER
ABSTRACT OF THE DISCLOSURE

Method and apparatus for processing ex-truded thermoplastic material for use in house siding by advancing a hollow extrudate from the die member through cooling and sizing baths followed by stress relieving the extrudate and thence cutting the extrudate into separate finished strips for final processing and packing.

Description

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This invention relates to extruding, and more parti-cularly to a new and improved method and apparatus for extruding thermoplastic polymer house siding.
In the extrusion process of thermoplastic materials, reliance is made on the die means for shaping the product from the extruder. In the manufacture of house siding, the extrudat~
is a relatively narrow width flat shePt of material having a turned over portion along one side edge to provide an interlock means. To handle this type of shape, the extrudate must be o high viscosity to prevent the distortion of the extrudate and prevent sagging of the siding in processing it. Cooling is generally done by air. The requirement of having a stiff melt ;-in combination with the type of cooliny generally applied would restrict the output to a range between 200 and 400 pounds per hour, Tha present inv~ntion provides a means for significantly increasing the extrusion rate by providing a method and apparatus for extruding the ther~oplastic house siding at a higher te~perature wherein the viscosity is relatively low by providLng a novel shape and providing means for handling the low vi9cosity extrudate~ By extruding the thermoplastic house siding in the form of a hollow rectangular shaped extrudate, then applying ~acuum sizing techniques to it, has made it much easier to process, handle and size the thermoplastic siding~ Since the melt can be processed at a higher temperature better properties such as high mechanical properties and excellent weathering characteri3tics can be developed in the material.
The invention provide~ a method of manufacturing house siding comprising the steps of extruding a hollow rectangular shaped extrudate, vacuum sizing and cooling said extrudate, stres relieving said extrudate, and thence cutting said hollow extrudate into two separat~ flat panel~ to form house siding panels.
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In another aspect of the invention there is provided a metho~ of preventing warping in extruded house siding which comprises the steps of extruding a continuous elongated synthetic thermoplastic extrudate in a heated plastic condition having a hollow rectangular cross section, vacuum sizing and cooling said extrudate, stress relieving said rectangular shaped extrudate, cutting said hollow rectangular shaped extrudate along its con-tinuous length into two separate continuous length siding, and thence cutting said shaped siding into house siding panels of predetermined length.
The present invention particularly contemplates an apparatus and method wherein an extrudate that is generally rectangular in cross-3ectional shape is initially cooled as by a spray, thereafter sized in two successive tanks, and thence stress relieved as by infrared heaters. The extrudate in its hollow shape is thence cut into two separate narrow width siding strips for embossing, after which the siding is cut to length.
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The invention is illustrated in a particular and preferred embodiment by refèrence to the accompanying dxawings in which:

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Fig. 1 is a side elevational view, partly sche~natic, of the preferred embodiment showing the continuous line apparatus for forming the house siding.
Fig. 2 is a side elevational view of a sizer showing the siding passing therethrough.
Fig. 3 is a cross-sectional view of the sizer taken along line 3-3 of Figure 2.
Fig. 4 is a cross-sectional plan view of the sizer taken along line 4-4 of Fig. 30 Fig. 5 is a cross-sectional view of the sizer taken along line 5-5 of Figure 3~ , Fig. 6 is a side elevational view of the cooling tanks with a portion of tank broken away along line 6--6 of Figure 7.
Fig. 7 is a cross-sectional view of the cooling tank taken along line 7-7 of Fig. 6.
Fig. 8 is a front elevational view of the stress ralieving means showing the house siding in rectangular cross ~ectional form.

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Fig. 9 is a front elevational view of the cutter means for separating the siding into two pieces.
Fig. 10 is a schematic showing of an embossing means.
Fig. 11 is a schematic diagram of the cooling means for the sizer and cooling tank.
D~TAILED DESCRIPTION
Referring to the drawings wherein lik~ re-ference characters designate like or corresponding parts throughout the several views, there is shown in Fig. 1 an ex~ruder 10 having a hopper 11 and a die means 12 at the forward portion thereof showing an extrudate 13 issuing therefrom. The die member 12 has a die opening that is contoured to a rectangular hollow shape, which in the examples to be described is that of two house siding sheets placed side edge to side edge similar to the configuration shown in Fig. 9.
The hollow extrudate from the extruder 10 is fed pas~ pre-cooling spray means l.5 which in Fig. 1 is shown as a single nozzle; however, more than one spray no~zle may be used. The extrudate is then fed to a cooling and shaping housing illustrated generally as 16 located directly in line with the extruder 10. The forward end portion of cooling and shaping housing has a rectangular shaped opening 17 in the form of two house sidings at its forward end, which opening 17 extends as a contoured reetangular shaped groove along the full length of housing 16. As seen in Figure 9, the siding has a folded over portion or ear projections 20 extending outwardly from the flat planar siding portion 21, a leg portion 22 with a . : . . .
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plurality of longitudinally extending ridges 23 on the outer surface and a longitudinally extending ridge 24 on the inner surface. (Fig. 3 shown without extrudate therein for clari~y). The single siding panel extends ~as viewed in Fig. 9) from between ridges 23-24 on the lower right hand portion of the extrudate to include the left hand leg portion 22 ~nd the adjacent inner ridge 24. The remaining portion forms a second longitudinally extending siding. As the hollow shaped siding passes through the sizer housing 16, a plurality of apertures 25 communicate with the upper and lower planar surfaces of the siding panel. A suitable vacuum is drawn on these apertures to maintain the siding surfaces in full con-tact with the contoured sizer opening to properly siæe the extrudate.
Housing 16 has three parallel bores 30 extending into the top portion of the housing and three parallel bores 31 (only one shown in Fig. 3), with their end por-tion interconnected by suitable bores 32. Bores 30 and 31 are connected to conduits 35 and 36 respectively, which in turn are connected to a vacuum pump 38.
Housing 16's upper and lower sections each have a plurality o~ horizontally extending parallel bores 39 whose end portions are interconnected by a pair of parallel spaced bores 40-41. The end bores 40-41 (top and bottom) are connected to inlet conduits 42, 43 and outlet conduits 42' and 43' respectively. Conduit 42 is connected to heat exchanger 45 from which cold water is directed to ~he sizer housing 16 to cool the extrudate passing therethrough.

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Thus, the shaped extrudate passing through sizer housing 16 has a vacuum applied to the outer surface to accurately form and size simultaneously cooling the siding.
The extrudate from sizer housing 16 is directed to a cooling tank 48. The front surface of tank 48 has an aperture therein which permits the movement of the extrudate therethrough. The extrudate is supported in its passage through the tank 48 by a plurality of spaced rollers 50 journaled on suitable bearings. The one end of each roller 50 has a recess 51 therein to receive the ear 20 of the extrudate, which acts as a guide to move the extrudate along a straight linear path through the cooling tank. The rear surface of tank 48 has a suitable aperture for ~he passage of the extrudate therethrough.
The tank 48 has a condult 52 along the upper and lower inside edges. Each conduit 52 has a plurality of nozzles 53 connected on its inner periphery for spraying a cool-ing fluid onto the outer surface of the hollow extrudate.
The hollow extrudate is then directed by a take away conveyor means 55 to the stress reliever means 56 which in the example shown has a housing 57 with four infrared heaters 58 mounted on the respective inside edges of such housing which direct the heat onto the respective corners of the extrudate as it passes therethrough. The extrudate is guided through the housing by a pair of spaced longitudinally extending guide plates 59 and 60, which in addition shield the remaining portion of the extrudate as it passes through the stress-relieving process.

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The hollow extrudate is then directed into the path of a pair of circular cutting means 62 which separates the hollow ex~rudate into a pair of separate flat house siding panels which are illustrated as 63 and 64 in Figure 1. The continuous lengths of siding are then directed to the embossing rollers 65 and 66, each having a back-up roller 67. The respective embossing rollers 65 and 66 along with back up rollers 67 are suitably driven and heated to insure the embossing onto such separate sidings.
The continuous moving length of siding has elongated holes pun~hed as by puncher 70 along one side thereof, which operation facilitates the fastening of the siding to the side of the house.
Each continuous moving siding is then fed past a guillotine shear 75 (as shown in Fig. 1) suitably powered for intermittent cutting for severing the siding into suitable lengths for stacking and shipping.
In the operation of the method and apparatus descrihed, the extruder 13 extrudes over a suitable man-drel and through a suitable shaped die, an e~trudate that is a hollow rectangu].ar shaped member with spaced projec tions that run the full length of the siding being ex truded. As the hollow shaped member issues from the ex-truder, it is cooled as by a water spray from nozzle 15 as it enters a sizing and cooling housing 16. The ex-trudate is sized by pulling a vacuum on the outer surface o the extrudate. The extrudate then enters a cooling tank 48 wherein the extrudate is sprayed with a cooling fluid as it is fed by a take-away conveyor 55 into a stress-relieving unit 55. As the hollow extrudate passes through ~he unit 56, the main portion of extrudate is , ...

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covered with only the respective corner being exposed to the h~ating by the infrared heaters 58. The respec-tive corners are stress relieved. After leaving the heating unit 56, the hollow rectangular shaped extrudate is separated by a pair of rotating cutters 62 into two separate L-shaped continuous length portions for passage past drill means 70 which drill holes along one side edge to facilitate the fas~ening of the siding to the house being sided. The separated sidings are then em-bossed by heated rollers 65 followed by cutting to pre-determined length panels.
Various modifications are contemplated and may obviously be resorted to by those skilled in the art with-out departing from the described invention, as herein-after defined by the appended claims, as only a pre-ferred embodiment thereof has been disclosed.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of manufacturing house siding comprising the steps of extruding a hollow rectangular shaped extrudate, vacuum sizing and cooling said ex-trudate, stress relieving said extrudate, and thence cutting said hollow extrudate into two separate flat panels to form house siding panels.

2. A method of manufacturing house siding as set forth in claim 1 wherein said vacuum sizing is done on the outer surface of said hollow shaped extrudate.

3. A method of manufacturing house siding as set forth in claim 2 wherein said hollow extrudate is pre-cooled prior to said vacuum sizing operation.

4. A method of manufacturing house siding as set forth in claim 1 wherein said flat panels are embossed by heated rolls after said panels are cut into separate panels.

5. A method of manufacturing house siding com-prising the steps of extruding a hollow rectangular shaped thermoplastic extrudate, cooling said extrudate immediately after said extruding, thence vacuum sizing and cooling said hollow extrudate as it is moved in a linear direction away from said extruder, thence cooling said sized ex-trudate to ambient temperature, thence heating the respec-tive longitudinally extending corners of said hollow ex-trudate as it is fed in a direction away from said ex-truder to stress relieve said corners, cutting said hollow extrudate into two separate flat L-shaped portions, and thence cutting said extrudate into predetermined length panels.

6. A method of manufacturing house siding of claim 5, wherein said separate flat L-shaped portions are embossed by heated rolls following said cutting of said hollow extrudate.

7. A method of manufacturing house siding as set forth in claim 6, wherein said stress relieving is done along the respective longitudinally extending corners of said hollow extrudate.

8. A method of manufacturing house siding as set forth in claim 7, wherein said heating is infrared heating.

9. The method of preventing warping in extruded house siding comprising the steps of extruding a continuous elongated synthetic thermoplastic extrudate in a heated plastic condition having a hollow rectangular cross section, vacuum sizing and cooling said extrudate, stress relieving said rectangular shaped extrudate, cutting said hollow rectangular shaped extrudate along its continuous length into two separate continuous length siding, and thence cutting said shaped siding into house siding panels of predetermined length .

10. The method of preventing warping in extruded house siding as set forth in claim 9, wherein said vacuum sizing is done on the outer surface of said hollow shaped extrudate.

11. The method of preventing warping in extruded house siding as set forth in claim 10, wherein said hollow extrudate is pre-cooled prior to said vacuum sizing, and embossing said panels of predetermined length after said stress relieving.