Method of making a molded article

A method of molding articles including the steps of continuously moving a forming mold and a band-like molding member in a first and second endless path, respectively, engaging the respective mold and member through a region of engagement to form a continuous open-ended molding cavity; injecting hardenable material into the cavity; intermixing and compacting the hardenable material before hardening into an article and then disengaging the mold and band before removing the article.

BACKGROUND OF INVENTION 
1. Field of the Invention 
This invention relates to an article molded in continuous strip form and 
the method and apparatus for the manufacture of the same. 
2. Description of the Prior Art 
The prior art, as exemplified by U.S. Pat. Nos. 4,137,034; 4,350,656; and 
4,352,654, contains a number of methods and apparatus for continuously 
molding individual articles or articles connected by thin runners. These 
prior art methods and apparatus incorporate continuously rotating cavity 
wheels and continuous bands for forming the walls of discrete cavities 
into which the molding material is injected. However, these prior art 
molding methods and apparatus were limited to molding individual elements 
or elements interconnected by intentional break zones to separate or 
snap-off individual elements. 
SUMMARY OF THE INVENTION 
The invention is summarized as a molded article, and the method and 
apparatus for making the same, that includes a body member formed in a 
continuous molding process by injecting hardenable material through spaced 
apart openings communicating with a continuous open-ended cavity moving in 
a given path. The sprues, formed in each opening and molded integrally 
with the body member upon hardening of the hardenable material, are 
severed from the body after removal of the body member from the continuous 
cavity. Hardenable material in melt form is continuously injected through 
a plurality of openings into the continuously moving open-ended cavity to 
initially fully occupy the cavity, with the foremost side of the material 
contained within the open-ended moving cavity, located upstream of said 
openings. As the moving cavity transports the material downstream, the 
outer skin cools and the volume of the melt shrinks whereby the downstream 
openings inject more hardenable material melt into the moving cavity to 
compensate for the shrinkage so that the final injection of melt to form 
the article fully occupies the cavity. The molded article is removed when 
the continuously moving members forming the continuous open cavity are 
separated. 
An object of this invention is a molded article that is readily formed of 
hardenable material in a continuous molding process. 
Another object of this invention is to sequentially inject hardenable 
material into a continuously moving open cavity that has one open-end, the 
speed of the members forming the open cavity being sufficient to maintain 
the hardenable material within the continuously moving open-ended cavity. 
Still another object of this invention is to thoroughly intermix the 
hardenable material and accommodate pressure variations within the system 
when molding an article of hardenable material. 
One advantage of the invention is that molded articles manufactured of 
hardenable material can be manufactured in continuous string form at 
greatly increased productivity 
Other objects, advantages and features of the invention will be apparent 
from the following description of the preferred embodiments taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION 
As illustrated in FIG. 1, an apparatus, indicated generally at 10, for 
continuously molding an article 12 includes a forming mold wheel 14, a 
continuous band 16 and an injection mechanism 18. Band 16 extends around 
wheel 14 and has circumference that is larger than the periphery of wheel 
14, whereby band 16 passes about a guide wheel 20, to disengage band 16 
from wheel 14 for a portion of its endless path. Injection mechanism 18 
includes a shoe 22 to engage and force band 16 against wheel 14 within an 
angle of engagement 26 defined by injection mechanism 18 and roller 24. 
Motor means 28 is drivingly connected to cavity wheel 14 for continuously 
rotating wheel 14 as well as continuously moving band 16 in an endless 
path with both wheel 14 and band 16 engaged and moving in the same 
direction past the injection mechanism 18 and roller 24. Wheel 14 and band 
16, when engaged together in the angle of engagement 26, to cover channel 
29, located in the periphery of wheel 14, form a continuous open ended 
molding cavity 30 for receiving molding materials injected by mechanism 18 
and then hardened within the cavity to continuously form the molded 
article. 
The molding apparatus shown in FIGS. 1-5 is designed for molding a 
continuous length article having a substantially U-shape in cross-section 
as shown in FIG. 6; whereas, the variation of FIGS. 7 and 8 is designed to 
mold in continuous length a specific product that can, in subsequent 
steps, be separated into individual elements. Many other variations can be 
devised for molding various articles. 
The apparatus of FIGS. 1-5 includes a continuous annular channel 29 located 
centrally in the periphery of wheel 14 that is driven by motor 28 to 
rotate in the direction R. Cavity 30, as shown in the embodiment of FIGS. 
1-5, is an open continuous elongated chamber of uniform cross-section and 
for purposes of example only will be described as an inverted U-shape. 
Injection mechanism 18 includes a shoe 22 whose lower surface 32 is curved 
to closely fit upon the outermost peripheral surface 34 of wheel 14 as 
well as the peripheral surface 36 of moving band 16 wrapped about wheel 
14. Pressure P applied to shoe 22 maintains the shoe in sliding engagement 
with band 16 as plastic resin melt F from an outside source enters through 
conduit 38 to interior chamber 40 of shoe 22. Electrical heater element 42 
located in the walls of conduit 38 maintains the melt F within conduit 38 
in a substantially fluid state. 
An electrical cylinder heater 44, centrally located within chamber 40, is 
positioned closely adjacent to the outlet 46 from shoe 22, to reheat the 
melt immediately prior to the melt entering annular cavity 30 as the melt 
will become slightly cooler and more viscous in moving from conduit 38 to 
chamber 40. 
A plurality of spaced apart openings 48 are located on the periphery of 
wheel 14 to form a connecting passage between chamber 40 in shoe 22 and 
annular cavity 30 in wheel 14. As wheel 14 rotates, band 16 moves with the 
wheel beneath shoe 22 and encloses cavity 30 on all sides throughout the 
angle of engagement 26, until band 16 moves past roller 24, at which 
point, band 16 separates from wheel 14 and annular channel 29 is 
uncovered. 
In operation of the apparatus of FIGS. 1-5, flowable plastic melt F is 
injected into conduit 38 from a supply not shown, where melt F is heated 
by heater 42 to retain its fluid-like character. From conduit 38, melt F 
enters chamber 40 of shoe 22 and, as it surrounds and flows past 
cylindrical heater 44, melt F is heated to a higher temperature that 
further reduces its viscosity. In so heating melt F in chamber 40, a thin 
coating of semi-solid plastic 50 overlays the interior walls of chamber 40 
as the temperature of the interior walls ar cooler than the temperature of 
the resin within chamber 40. Cavity wheel 14 driven by motor 28 and band 
16 are guided into engagement beneath shoe 22 to form and enclose annular 
cavity 30 through the angle of engagement 26. 
The plastic resin or melt F, recently heated by heater 44, passes through 
outlet 46 and through opening 48 from chamber 40 to cavity 30 where it 
flows upstream against the direction of movement of cavity 30. Another 
coating 52, similar to coating 50, is formed on the inner walls of cavity 
30 as melt F flows upstream of shoe 22 and openings 48. Coatings 50 and 52 
aid in the movement of melt F through the system because the resistance to 
the flow between the freely flowing plastic resin F and coatings 50 and 52 
is substantially less than the resistance to the flow between plastic melt 
F and the interior surface of any portion of conduit 38, chamber 40 and 
cavity 30. Heating plastic melt F to a higher temperature by the use of 
heater 44 at outlet 46 of chamber 40 and prior to its passage through 
openings 48 into cavity 30, provides a lower resistance to the flow 
between the melt F and the interior surfaces of melt coating 52. 
As shown in FIG. 5, melt F downstream of openings 48, 48' and 48" 
connecting outlet 46 of shoe 22 has fully occupied cavity 30; and, because 
of the rotation of wheel 14 with band 16, is now cooling and solidifying 
into an article 12 of solid plastic resin and is moving rapidly away from 
shoe 22. Thus, newly heated plastic resin melt F that enters cavity 30 
through upstream opening 48 cannot flow downstream against solid plastic 
resin forming article 12; and, because it is under pressure from injection 
mechanism 18, flows upstream. 
However, band 16 and channel 29 forming cavity 30 have surfaces which are 
relatively cool as they come together beneath shoe 22 and because of their 
linear speed, melt F injected through opening 48 can only travel a short 
distance upstream before melt F is turned back on itself. It must be 
appreciated that cavity 30 is moving at a relatively high speed past shoe 
22 so that the upstream flow of melt F stops at a relatively constant 
distance from shoe 22 as the volume of melt being injected into cavity 30 
is almost the same as the volume of melt moving past opening 48. Melt F 
then forms, in effect, a foremost side 54 past which melt F cannot flow 
further upstream. 
Because melt F is injected into an open-ended cavity whose sides are 
continuously moving in a direction past the shoe through which the melt is 
injected, the melt is subject to turbulent flow which intermixes the melt 
resulting in a quality product. Importantly, use of an open-ended cavity 
system, with its movable upstream face, diminishes the pressure surges 
that normally occur when a fixed volume of plastic melt is injected by 
positive displacement means into a cavity system. Accordingly, foremost 
side 54 changes position relative to upstream opening 48 as it slightly 
advances and retreats as a result of pressure variations. 
The outer surfaces of melt F, upstream of the first opening 48 in wheel 14, 
engage the cool interior surfaces of band 16 and channel 29 to cool and 
solidify to form a skin or coating 52 having a greater viscosity 
approaching solidification. More of the melt forming skin 58 cools to a 
semi-solid state as the hardenable material moves past opening 48 towards 
opening 48' so that semi-solid skin 58 becomes thicker and the volume of 
fluid melt material forming melt core 56 enclosed within skin 58 is 
reduced as the hardenable material progressively cools from its outer 
surfaces to the center of melt core 56. 
For purposes of illustration only, skin 58 which envelopes core 56 of melt 
F injected through opening 48 of FIG. 5, is shown as having an increased 
thickness as the hardenable material enclosed within cavity 30 moves past 
openings 48, 48' and 48". 
Additional plastic melt F' is injected into cavity 30 through opening 48'. 
Melt F' will enter melt core 56 where it will exert pressure outwardly 
against the inner surface of skin 58. 
In like manner, additional melt can be injected through opening 48" to 
further pressurize core 56. 
As shown in FIG. 5 the melt injected through opening 48 forms skin 58 which 
becomes thicker as it cools and moves downstream of opening 48 where it 
eventually becomes solid to form article 12. Similarly, to further 
illustrate the process, a semisolid envelope 60 of hardenable material is 
formed intermediate skin 58 and melt core 56. It is to be understood that 
newly injected material entering openings 48' and 48" will exert pressure 
on the material forming the article which pressure is directed from the 
inner core outwardly towards the skin. Because the melt is injected 
substantially internally in this continuous molding process, the outer 
surface of the final product has a blemish free exterior. 
The length of the arrows showing the direction of flow of melt F, F' and F" 
is somewhat proportional to the volume of material injected through the 
respective openings 48, 48' and 48". 
The above described sequence of operation of the apparatus as wheel 14 and 
band 16 pass beneath shoe 22 is continuous and can involve a wheel 14 that 
has many more openings 48, 48', and 48" communicating with outlet 46 of 
chamber 40 than is shown. It should also be understood that openings 48, 
48'and 48" can be eliminated and a plurality of openings (not shown) can 
be located in band 16 to directly inject melt from chamber 40 through the 
openings in the band and into cavity 30, to obtain the results as 
described herein. 
Article 12 cools to solid form throughout its travel through the angle of 
engagement 26 and once past roller 24 can be removed from annular cavity 
30 when band 16 separates from wheel 14 and before band 16 passes about 
roller 24. The resulting article can be wound upon a reel or cut into 
given lengths (not shown). 
As shown in FIG. 6, article 12 includes equally spaced apart sprues 64 
which are formed by the melt F remaining in opening 48 once wheel 14 moves 
past shoe 22. Sprues 64 can be used to carry or position article 12 in 
subsequent operations. 
FIGS. 7 and 8 show another embodiment of an article 66 that can be made by 
this method and on this apparatus. Article 66 has a body 68, that for 
representation is circular in configuration. In this embodiment, a 
continuous member 70 formed in open-ended channel 82 of FIG. 8 extends 
along one side and has a connecting sprue 72 extending between article 68 
and member 70. Similarly, a connecting element (not shown) can 
interconnect adjacent articles 66 whereby a plurality of articles are 
carried on member 70 in a uniform repetitive manner for subsequent 
operations. 
As shown in FIG. 8, band 76 overlies wheel 78 with openings 80 exposed to 
accept melt under the edge of band 76. It has been found that melt will 
pass through openings 80, enter open-ended channel 82 that will form 
continuous member 70, flow into connection 84 that will form element 72, 
thence flow into channel extension 86 to form body 68. Again, the flow of 
melt in open-ended channel 82 will be turbulent to intermix the melt both 
in channel 82, as well as channel extension 86. The injecting of melt into 
open-ended channels, such as 82, will operate and perform in a manner 
similar to that described above with reference to article 12 to obtain the 
desired results. 
In FIG. 9, there is shown still another embodiment of the apparatus in 
which a blocking member 90, resiliently mounted to move arcuately on 
member 92, is located in cavity 30 upstream of face 54 of melt F. Blocking 
member 90 moves within cavity 30 and has a cross-sectional configuration 
that will substantially fill cavity 30 so that it will slidingly engage 
the inner surfaces of cavity 30 including lower surface 32 of band 16. If 
extreme pressure surges or a very low viscosity melt is injected into 
cavity 30, face 54 can advance upstream of its normal range, but 
resiliently mounted blocking member 92 will inhibit such movement by 
adjusting its position in response to the change in pressure and move 
accordingly within cavity 30 to prevent any melt from being ejected from 
cavity 30 upstream of the engagement of band 16 and wheel 14. 
The foregoing invention is useful for molding articles that are 
dimensionally correct with a uniform composition throughout. Furthermore, 
the product in continuous form manufactured on this apparatus and method 
readily lends itself to subsequent manufacturing operations. Also, the 
entire apparatus can be readily modified to incorporate a heated wheel and 
band operating at a temperature suitable for using a thermo-setting type 
plastic. 
While not shown in the drawings, it is to be understood that the inner 
surface of band 16 and/or channel 29 can have either raised or recessed 
surface configurations resulting in recessed or raised surface 
configurations in the article. 
Since many modifications, variations and changes in detail may be made to 
the embodiments described above and shown in the accompanying drawings, it 
is intended that all matter described in the foregoing description and 
shown in the drawings be interpreted as illustrative and not in a limiting 
sense.