ANI'EC '82
`
`The 40th Annual Technical Conference and
`Exhibition of the Society of Plastics Engineers
`
`“Plastics — Meeting Challenges
`Of the FUture”
`cameraman-t
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`UNN. or LOWELL
`Emma. 3-16. 0591".
`LOWELL MA 01854
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`i :
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`H
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`San Francisco Hilton
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`F. Dynacraft BSC, Inc.
`" Exhibit 1010
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`“
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`Dynacraft V. Mattel
`IPR2018-00042
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`

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`BLOW MOLDING HIGHLY IRREGULAR SHAPED PARTS
`WITH MOVING MOLD SECTIONS
`
`l. L. fleters
`
`Phillips Chemical Company
`Plastics Technical Center
`Bartlesville, OK
`
`INTRODUCTION
`
`Technology is presented disclosing methods of using moving mold
`sections to blow mold highly irregular part shapes in high den-
`sity polyethylene.
`The significance of the technology is that
`it is the onlyknownmeans to blow mold these parts in one piece.
`Although it is fairly common to move mold sections of a blow mold
`to release undercuts and permit part removal, molding techniques
`to affect or control wall
`thickness is used by relatively few
`molders.
`The ability of these new molders to blow mold uniquely
`shaped parts has paid dividends by eliminating or reducing costly
`secondary operations. Three of the more important moving mold
`section techniques as developed at the Plastics Technical Center
`of Phillips Chemical Company are discussed.
`
`INTEGRAL HANDLE LID (ll
`
`High density polyethylene water cooler lids with an integral
`handle have been blow molded commercially since 1955. Several
`million lids of three sizes have been produced using movable
`mold sections of blow molds to form handles.
`A lid on a five-
`gallon cooler is shown in Figure l.
`
`The mold consists of two basic mold halves — one half for the
`top of the lid and the other half for the bottom.
`The top half
`contains the movable ”slides” to form the handles.
`The bottom
`half of the handle cavity is located in the movable slides and
`the top half in the stationary part of the mold.
`The horizontal
`slides are located under a face plate as shown schematically in
`the "open" position, Figure 2.
`
`The molding sequence starts with a pre-pinched and slightly pre-
`blown parison between the two open mold halves.
`The handle
`slides are open at this time. The mold halves are then closed
`on the parison.
`The closing action of the mold compresses and
`forces part of the parison into the handle cavity.
`A horizontal
`cut through the mold showing the parison ”bubble” during mold
`closing is illustrated in Figure 3.
`(A photograph of a produc-
`tion mold with the slides open is shown in Figure 4.)
`The slides
`are then closed almost simultaneously with the mold closing.
`The
`blow air is introduced through a needle into a flash "pocket"
`under the handle.
`The blow air forms the parison to the flash
`pocket shape, and then flows throUgh two open pinch blade spots
`under the handle, resulting in the lid body being blown through
`the handle passage as illustrated in Figure 5.
`The handle slides
`open with the mold opening to release the undercut and allow the
`part to eject.
`
`Processing efficiencies are excellent with precise control of the
`following variables:
`timing, distance of slides opening, and speed
`of slides movement.
`The amount of pre-blow air and blow air
`timing also must be regulated and synchronized accurately with
`respect to both mold closing and slides closing.
`
`lid has flash which must be trimmed around the pe-
`The resultant
`riphery and under the handle; otherwise the handle is completely
`finished as the slides and stationary mold cavity form the handle
`without flash. Good wall distribution is achieved as can be seen
`in the 3/4 part photograph of a connercially produced lid shown
`in Figure 6.
`
`INTEGRAL HANDLE, DDUBLE HALLI
`
`INTERNALLY THREADED LID {2)
`
`Further development work resulted in a second high density poly-
`ethylene one-piece water cooler lid also having an integral
`handle plus an internally threaded double wall skirt. Many mil-
`lions df'ffiese water cooler lids shown in Figure T have been pro-
`duced commercially since lSEB.
`
`Again there are two basic mold halves - one half to form the top
`and outside skirt and the other to form the internally threaded
`inside wall of the lid.
`The top half of this mold differs con-
`siderably from the first lid mold. This top mold half is split
`into two horizontally movable quarter mold sections to form the
`
`handle as shown in the upper part of the sectioned illustration,
`Figure 8.
`{This is in contrast to the first lid mold in which
`the slide sections only are movable.) The bottom half is also
`quite different
`in that double wall blow molding technique is
`utilized to form the double wall skirt, {lower illustration,
`Figure 8).
`A third distinction is the melding of the internal
`threads on the inside of the double wall. This necessitates an
`unscrewing core which releases the threaded lid off the core on
`mold opening.
`h photo of a commercial mold with quarter mold
`sectiois open is shown in Figure 9.
`
`The molding sequence requires that a ore-pinched and pro-blown
`parison be dropped between the mold halves. The quarter molds
`of the upper half are open at the time the parison is extruded.
`The press closes and almost sinultaneously the quarter molds are
`closed by air or hydraulic cylinders to pinch the parison sector
`which forms the handle. The closing of the mold halves compresses
`and “balloons“ the ore-pinched parison over the threaded core,
`"flashing" the cavity periphery.
`Blow air is introduced, forming
`the part as shown in the horizontally sectioned illustration,
`Figure l0.
`
`the threaded core rotates
`the same time the press opens,
`At about
`to unscrew the part off the core. After a short delay,
`the
`quarter mold sections open.
`The delay on the quarter mold open-
`ing "holds“ the lid so that the threaded core can unscrew rather
`than rotate the entire lid. Splitting the handle section of the
`mold into quarter sections results in the advantage of being able
`to mold a complex,
`irregularly shaped part with excellent wall
`distribution, as shown in the sectiaied lid of Figure ll.
`The
`disadvantage is ”flash“ in two planes (Figure 12) which requires
`more trimming and regrinding.
`
`the lid can also be
`in Figure 13,
`As the photo of the parts shows
`molded with internal
`threads in a compression molded solid wall.
`This type of lid has excellent
`thread strength but it does not
`have the rigidity of a lid with a double wall skirt; it tends to
`warp, and the outside appearance is inferior to the blow molded
`double wall part because of “sink" and “drag“ marks.
`DRUM INTEGRAL HANDLING Rlfifi
`
`A SG-gallon high density polyethylene drum with a handling ring
`integrally molded in the bottom chime area has been developed at
`the Plastics Technical Center in Bartlesville, OK.
`The handling
`ring allows metal drum lifting equipment to be used.
`A ”double
`wall" relatively sharp radius chime was molded in the top (bung
`end} of the drum.
`The handling ring and sharp radius corner was
`located in their respective ends for mold building convenience
`and would be reversed in a production mold.
`A photo of the drum
`is shown in Figure 14.
`
`Although similar to the European "L Ring“ drum in appearance and
`function,
`the Plastics Technical Center drum mold was designed
`and built independently. This drum mold has been used to develop
`molding techniques,
`to mold drums for testing (including handling],
`and for the evaluation of resins.
`
`Each end of each mold half has amovable section referred to as
`a "plug".
`The movable plug in the end of each mold half is semi-
`circular, as shown in Figure 15. The open and closed positions
`of the plugs during molding are shown by the “dry cycle“ photo-
`graphs of one mold half (Figures l5 and 16, respectively).
`The
`mating plugs of two closed mold halves form the head and bottom
`of the drum mold.
`The plugs are moved by means of hydraulic
`cylinders on each end and both sides of each mold half [Figure
`l7).
`The 3 l/Z“ diameter hydraulic cylinders are securely
`mounted to the mold body and plug assemblies. Large cylinder
`rods (2 1/2” diameter} are used to assure smooth plug movement
`with no “cocking" caused by possible variations of hydraulic flow
`or pressure in the cylinders. Good wear plates are required be-
`tween the plugs and mold body to allow plug movement under ma-
`chine clamp and blow air pressures.
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`711
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