Note: Descriptions are shown in the official language in which they were submitted.
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1 The present invention relates to a method of
2 manufacturing siding from thermoplastic resin material.
3 More particularly, the invention concerns an improvement
4 in the apparatus and method of cooling and sizing of
S the siding.
6 Generally, the method of producing siding
7 from thermoplastic resin materials comprises the extrusion
8 of siding through a die orifice generally conforming to
9 the cross sectional shape of the siding, followed by
cooling and sizing steps. The hardened siding is cut
11 to the desired lengths and may be subjected to further
12 machining or manufacturing. The resins most usually
13 emp?oyed are polyvinyl chloride resin material, although
14 other thermoplastics may be used.
Prior to extrusion, the resin may be formulated
16 with pigments (such as titanium oxide to produce white
17 siding) or other constituents, such as lubricants
18 (paraffins), antioxidants (BHT), flame retarding additives
19 (chlorina'ed waxes) and the like.
There are various properties which are desirable
21 for the siding. One of the most obvious is the ability
22 of the siding to retain its configuration when applied
23 to a surface and exposed out of doors. One such property
24 is retention of the surface and linear appearance of the
siding on exposure to heat. Some resin siding has a
26 tendency to buckle or bulge, which is referred to as
27 '`oil canning". The "oil can" test so called determines
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l whether a particular siding undergoes this warping under
2 specified conditions. To pass the test, no warping ~ust
3 be observed under the test conditions.
4 It is an advantage of the present invention
that the siding produced thereby will withstand vigorous
6 oil-can test requixements without warping and that the
7 manufacturing line can be operated at higher speeds. It
8 is a further advantage of the present invention that the
g imp-ovement described herein may be made on existing equip-
ment.
ll The present invention is an improvement in
12 the apparatus and process for manufacturing resin siding.
13 Briefly, the apparatus of the present invention
14 is an improvement in an apparatus for making thermoplastic
siding which has a butt edge, a hanger edge and an interven-
16 ing panel comprising an extruder with a die having a
17 substantially horizontally oriented orifice which sub-
18 stantially conforms to the cross section of the siding, a
19 cooling and sizing section downstream from said die and a
pulling means downstream of said cooling and sizing
21 section, said cooling and sizing section having a lower
22 forming surface composed of a plurality of curved templates
23 for imparting curvature to the siding panel with the con-
24 cavely curved side presented upwardly and at least one up-
per forming surface covering a portion of said lower form-
26 ing surface and composed of a curved plate corresponding
27 to the curved templates and means for delivering air
28 for cooling into said cooling and sizing section, wherein
29 the improvement comprises a plurality of notches along
edges of said curved plate adjacent to the locations of
31 said butt and hanger edges and extending to e~pose a portion
32 of said panel adjacent to said butt and hanger edges when
33 said siding is in place in said apparatus and a plurality
34 of means to direct air onto a portion of the upper and
lower forming surfaces along the edges and adjacent por-
36 tions thereof corresponding to the butt and hanger edges
1 of the siding, at least some of said air means being
2 proximate to the ~utt and hanger edges and the panel area
3 adjacent thereto.
4 In addition to the coolin~ means directed
specifically onto the edges of the former and at close
6 proximity thereto there may be other sources of air such
7 as blowers generally above and below the entire former
8 section which tend to cool over a portion of forming sur-
9 faces generally. Generally the cooling air is drawn from
10 the surrounding environment and is ambient and is generally
11 in the range of 50 to 80F more preferably 60 to 70F.
12 The air means proximate to the area of the
13 lower and upper former surface edges performs an important
14 function in that the temperature difference along these
15 edges ~ T) is greater than ~ of the central portion of
16 the formers. It is believed that the rapid cooling of
17 the edges and the slower cooling of central portion of the
18 siding as obtained accordin~ to the present invention are
19 the reason for the improved siding material which gives
20 higher oil-can test results (i.e., will withstand higher
21 temperatures without buckling or warping), 12ss off
22 specification product and higher production line rates.
23 The more rapid cooling of the edges is further
24 obtained by the notches in the upper former surface which
25 expose the siding passing thereunder. By this means, the
26 sizing and shaping function of the upper former is maintained,
27 since only a portion is removed and the increased cooling
28 obtained.
29 It has also been found that at least the central
30 portion of the upper former surface should be insulated to
31 prevent too rapid cooling of the central portion of the
32 panel. The portion of the upper former surface around the
33 notched areas may be similarly insulated to further control
34 the cooling of the edges of the siding. These adjustments
3~ may be made for each instal~ation and manner of operation
36 in order to optimize the process.
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1 The lower former surface is comprised of a
2 plurality of vertical spaced templates. Hence cooling air
3 directed from the lower side of the apparatus readily finds
4 its way onto the siding through the open structure of
the templates. The adjustment of this flow of air in
6 conjunction with the flow onto upper former surface is
7 again a mechanical adjustment easily made to optimize each
8 particular apparatus.
9 In addition to the apparatus discussed above,
there may be an embossing roll located between the extruder
11 and cooling and sizing section, where various patterns
1~ such as wood grain may ~e added to the siding.
13 The process of the present invention comprises
14 extruding a thermoplastic resin at a temperature sufficient
to plasticize said resin, generally over 300F and pre-
16 ferably 350 to 400F in a generally linear path into a
17 continuous belt thereof having a butt edge, a hanger edge
18 and an intervening panel, and passing said belt through
19 a cooling and sizing section, said belt of thermoplastic
resin is hardened into siding wherein the improvement com-
21 prises in a first zone supporting the lower surface of
22 said belt to form a concave upper surface, and applying
23 cooling air onto said butt and hanqer edqes and the adjacent
24 area of said panel on the uPper and lower surface thereof
from sources proximate thereto, in a second zone support-
26 ing the lower surface of said belt and enclosing a portion
27 of the upper surface of said belt to form a concave upper
28 surface and applying cooling air on the butt and hanger
29 edges and the adjacent area of said panel on the upper
surface thereof from sources distal thereto ànd in a third
31 zone supporting the lower surface of said belt, enclosing
32 a portion of the upper surface of said belt to form a con-
33 cave upper surface and appl~ing cooling air onto said butt
3~ and hanger edges and the adjacent area of said panel on
the upper surface thereof from sources proximate theretoO
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1 In a preferred arrangement further cool air
2 is subsequently applied to the upper surface of the belt
3 from a distal source, However, the siding is in its com-
4 pleted form at this point and the further cooling is to
bring the product closer to room temperature.
6 The invention will be better understood by
7 reference to the drawings wherein:
8 Fig. 1 is an overall outline view of the major
9 components of the equipment.
Fig. 2 is a schematic view of the process manu-
11 facturing line.
12 Fig. 3 is a perspective view o~ a portion of
13 the former of the first zone of the cooling and sizing
14 section-
Fig. 4 is a cross sectional representation of
16 the siding material extruded and passed through the
17 apparatuS~
18 Fig. 5 is a cross sectional representation of
19 the former of the second zone of the cooling and sizing
section.
21 Fig. 6 is a cross s~ctional representation of
22 the former of the third zone of the cooling and sizing
23 section.
24 Fig. 7 is a perspective view of a portion of
the upper former of the third zone of the cooling and
26 sizing section.
27 An extruder apparatus A is shown in Fig. 1
28 at-the right end of the siding production line. The
29 extruder is adapted to receive powder polyvinyl chloride
resin compositions and to heat and plasticize the resin
31 then deliver it into and through an extrusion die B. The
32 extrusion die is formed of various passages, including an
33 inlet passage for receiving the plasticized resin from the
34 extruder and a discharge orifice of cross sectional shape
suhstantially conforming with the cross section of the
36 siding.
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1 After the siding exits from the discharge
2 orifice of the die, the siding is still soft or in
3 plasticized condition and is passed through a pair of
4 nip rolls D, the upper one of the pair being an embossing
roll, to thereby impart a grain texture to the face of the
6 siding. After leaving the embosser, the siding passes
7 into and through the cooling and sizing section C, wherein
8 the siding is hardened in the desired cross sectional
9 shape and form.
The siding F is advanced through this cooling
11 and sizing section hy means of the puller mechanism E,
12 after which the siding is cut in the desired length, nail
13 holes are punched or other machinery operations performed.
14 Although the extruder as represen~ed in Fig. 1
is of the multiple screw type, a variety of known types of
16 extrusion equipment may be used. Similarly, although the
17 particular embodiment depicts an extruder adapted for
18 delivery of the resin (preferably polyvinyl chloride) as
19 a powder, other feed systems adapted for receiving and
plasticizing pellets, prill or granules may be employed.
21 The die will substantially correspond to the
22 cross section shape of the extruded siding, with appropriate
23 allowances as known in the art to compensate for swelling
24 and/or shrinkage of the extruded resin and produce the
~5 hardened end product of the desired shape and size.
26 After leaving the embossing rolls D, the siding
27 enters cooling and sizing mechanism C which is comprised
28 o~ three zones 10~ 12 and 14 ~hich are described more fully
29 hereafter. ~Blo~rers 1~, 18, 20 and 2~ are shown as possible
sources of t~e cooling air as discussed below, although
31 a single plant supply can be used for any or all of the
32 air sources and any other ~hich may be added. In this
33 regard, it is desirable to have a final air hood G, which
34 i~ located between the cooling and sizing section C and
puller mechanism E which (air hood G) blows directly onto
36 the entire upper and lower surface of the hardened and
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1 substantially cooled siding. This last cooling occurs
2 after the desired "oil can" properties are obtained by
3 the control of the cooling and sizing section zones and
4 merely removes heat in a substantially equal manner from
the entire siding.
6 The cooling and sizing section is comprised of
7 three subsections or zones lO, 12 and 14, in which the cool-
8 ing and sizing of the still sot siding is accomplished.
9 Although each zone is somewhat similar to the other zones,
there are variations which have been devised to obtain
ll the desired improvement in line speed and product quality.
12 Each zone contains a former which facilitates the shap-
13 ing of the siding. Each zone in addition to having a
14 somewhat different former is also separately controllable
as to the cooling which occurs therein. It should be
16 appreciated that the former and the cooling are closely
17 related and their interdependent relationship is the means
18 of the improved results.
l~ Each zone contains a lower former surface. The
lower former surface is substantially the same in each
21 zone and is shown in ~ig. 3. Fig. 3 is a perspective
22 view of the first zone lO into which the moving siding
23 passes. This zone has only a lower former 30 which is
24 comprised of a plurality of templates 40 which are spaced
apart and arranged vertically so that the lower surface
26 Of the siding is contacted by only the thin edge of
27 templates~ thereby reducing the drag or friction as the
28 siding passes through.
29 The lower former in each of the other two zones
12 and 14 are substantially the same as that of zone lO.
31 The lower former templates are supported in each zone by
32 bars (not shown~ which pass through openings 41 and 42.
33 In the preferred apparatus zone lO, 12 and 14 have a
34 similàr number of templates spaced about the same distance
apart, The spaciny is obtained in the usual manner with
36 spacers (not sho~n~ on ~he bar ~not shown) between the
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1 templates and appropriate gripping means (not shown)
2 such as nuts threaded on the bars and attached to sup-
3 port means (not shown) in each 20ne. Generally about
4 four inch spacing of templates is usual in zones three
feet long.
6 The templates have a concave surface adjacent
7 to the siding which serves to shape the sidin~.
8 Turning now to a consideration of the cool-
9 ing arrangement in zone 10, two sets of air bars are
located on each side of the former adjacent to the butt
11 edge 43 and the hanger edge 44 of the siding. Fach air
12 bar 31, 32, 33 (hanger edge) and 34, 35, 36 and 37 (butt
13 edge) has openings 45 therealong which direct the air
14 therefrom onto the respective edges of the siding as it
passes, but not onto the central panel section of the
16 siding. The air bars are held in place by members 46
17 and 47 and the members and air bars are mounted by any
18 conventional means in zone 10. For example, the members
19 46 and 47 may be attached to hinged elbows (not shown)
which are subsequently attached within the zone in order
21 to be retractable from the rormer templates 40 for ser-
22 vicing and repair of the latter.
23 It should be apparent that each zone 10, 12
24 and 14 is enclosed in a chamber shown ir Figs. 5 and 6
25 which has an opening at two opposite ends along the
26 machine line. The chamber provides the means of control-
27 ling the temperature and also provides the structure onto
28 which the various former and cooling components are
29 attached. This is all quite conventional and details to
the attachment of these components in the chamber are not
31 necessary for one of ordinary skill in the art in order to
32 obtain the novel improvement in apparatus and equipment
33 as disclosed herein.
34 Fig. 4 shows schematically how the air bars
deliver air onto siding 48 to obtain cooling, primarily
36 of the hanger edge C and the butt edge A while omitting
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1 the ma j or portion of the panel portion B . In this zone
2 the air bars are 1/2 ID tubing having 1/16 inch diameter
3 holes spaced 2 inches apart therealong. The air was de-
4 livered to the tube at 5-50 psig as required at about 50-
60F. The small arrows in Figs. 4, 5 and 6 represent
6 direction of air flow.
7 The former of zone 12 is aepicted in Fig. 5.
8 The former comprises the templates 40 as described in
9 zone 10 which comprise the lower surface, and the plate
50, which extends the length of the templates of zone 12
11 and which has a curved surface corresponding to the curve
12 in the templates 40, and which forms the upper former
13 surface. The upper former surface is hingedly mounted
14 (not shown) on the left hand side to be raised off of
the lower former surface 40 in the same dir~ction as the
16 hinged cover 51 on chamber 53. Means (not shown) are
17 also provided to space the right hand side of upper former
18 surface (plate) 50 the appropriate distance from the
19 lower former surface (templates) 40. Air i5 supplied to
this zone 12 by air hood or cover 51 through flexible
21 conduit 54 and is directed generally downward in the
22 area of the hanger and bu~t edges of the siding, although
23 it is not directed thereon with the close control of the
24 air bars of zone 10, for example. The lower former tem-
plate 40 is shown mounted on bars 56 and 57.
26 The plate 50 has notches along the edges cor-
27 responding ~o butt and hanger edges of the siding, as
28 shown in Fig. 7, which is the upper former 60 of zone
~9 14, differing only in the extension of the insulation
55 over the entire surface of the upper former surface
31 60 including the lips on either side of the notches.
32 Fig. 6 represents the Placement of the former
33 in the third zone, zone 14. There are templates 40
34 spaced apart and the upper former surface, lplate) 60
has the configuration shown in Fig. 7. The upper surface
36 of the plate is covered with insulation 62 except for the
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1 lips 63 which extend on either sides of notches 67. A
2 rib 61 is located at the end of the plate and can provide
3 the point for attachment of hinges in order to hinge the
4 upper former as the hood 68 is provided with hinges 6~ on
5 the left hand side of chamber 70.
6 Two air bars 71 and 72 previously described for
7 zone 10 are located above the upper former to direct air
8 at close proximity onto the exposed portion of upper former
g surface 60, the siding passing notch 67 and the adjacent
10 han~er and butt edges.
11 A xefinement and preferred manner of construc-
12 tion of the upper formers 50 and 60 is the asbestos cover-
13 ing 64 shown in Fig. 7 which is on the side toward the
14 siding. This additionally insulates the central panel
15 area of the siding. The air bars of zones 10 and 14 are
16 about 1 to 2 inches away from the surfaces on to which the
17 air is directed.
18 To demonstrate the improvement that has been
19 obtained by the present invention, it can be noted that
20 the previously operating manufacturing line producing 8
21 inch wide polyvinyl chloride siding was able to run at up
22 to about 250 pounds per hour output of finished siding with
23 variable properties on the "oil can" test, generally up
24 to about 125F. After modification of the production
line according to the present invention, production was
26 raised to greater than 300 pounds of product siding per
27 hour with average "oil can" test results of 150+F.
28 Referring to Fig. 2, a schematic of the present
29 system is shown. The temperature at four comparable points
30 W, X, Y and Z was measured for the prior apparatus and
31 the present invention at a, b and c points of Fig. 4 on
32 the siding which shows:
PrevioOus Process PresentOInvention
3 Positlon a b c a b c
4 W 325 320 320 320 320 325
5 X 25~ 235 260 250 230 260
6 Y 200 255 230 160 ~00 155
7 Z 115 120 123 100 105 100
8 This shows that the cooling of the central panel of the
g siding is reduced and the cooling of the outer portions
10 increased in the cooling section.
11 In the oil can test three sections of 6 foot
12 length siding are mounted on a vertical wall. A six foot
13 long heat source consisting of infrared heat lamps with
14 a maximum watt density of 6Q0 watts/lineal foot is mounted
15 32 inches from the wall facing the test siding.
16 A thermocouple is attached to the back slde of
17 the siding. The heat passing ~hrough the siding is recorded.
18 The test requires that there be no buckling or warping
19 (oil canning) up toa specified temperature; present~y Canada
2~ requires the siding pass the test at 120F and a somewhat
21 lower requirement is required in the United States of
22 AmeriCa-
23 As extrudate resin siding grows in use, it can
24 be expected that higher performance requirements will be
25 made and that closer specifications will be required. The
26 present improved process obtains a more uniform and pre-
27 dictable product with higher performance.
