Note: Descriptions are shown in the official language in which they were submitted.
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BLOW MOLDING PALLET ASSEMBLY
The present invention relates to an improvement in a
pallet assembly for trans~erring one or more workpieces
between loca~;ons dur;ng wh;ch tran~fer a manufactur;ng
S operat;on takes place. A particular, though not
exclus;ve, aspect of the invention is a pallet assembly
for transferr;ng a plural;ty thermoplastic resin
preforms through a blow molding operat;on and thereafter
releas;ng the bloun product ;n connection with wh;ch the
present ;nvent;on will be described.
Blow molding thermoplastic organic resins to form
hollow containers such as bottles for beer, carbonated
beverages, and the like is a known art and is the
preferred use for the present invention. Suitable
thermoplastic resins include resins which are b;axially
orientable such as polyethylene terephthalate and
polypropylene. The biaxial or;entation property
requires delivering the resin to the blow mold at a
temperature where it can so orient, which is generally
20 within the range between the res;n softening po;nt and
the resin melt;ng point.
The present ;nvent;on ;s a pallet assembly and
provides a means to transport an injection molded
preform rnade of the resin from 3 preheating oven or
25 other means for adjusting temperature (e.g. through a
cooler from the injection mold) to the blow mold thence
to a discharge po;nt; or more broadly from one location
where the means is loaded ~ith a ~orkpiece, through a
manufacturing location such as a blow molding procedure,
then to a second location for discharge.
The present invention is adapted to handle such
resin for blow molding in the form of an injection
molded hollow preform which in turn is shaped like a
test tube that has external threads about its open end~
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The body of the preform has been heated ~o an or;enting
temperature but the threaded end has been kept cool,~
unheated because such end is not to be blown.
Commonly used apparatus for locating and support;ng
preforms is described and illustrated in U.SO Patent
4,185,812. Such apparatus includes a pallet per se
which comprises - a pallet shuttle constitut;ng a base
on which the other members of the assembly are mounted;
locator means on said shuttle for posit;vely locating
said shuttle relative to adjacent machine eLements; a
workp;ece securing and locating assembly supported on
sa;d shuttle further compris;ng gu;de means mounted on
sa;d shuttle, a pair of jaws for engaging a workpiece
therebetween mounted on said guide means at least one of
~hich jaws is rec;procably and adjustably to move
between closed and open positions which respectively are
the positions for securing a workpiece for and receiving
or releasing a workpiece, means for biasing said jaws
together, a workpiece locat;ng member supported on sa;d
shuttle to rece;ve and reg;ster a workpiece w;th
reference to sa;d shuttle to rece;ve and reg;ster a
workpiece with reference to said shuttle, sa;d jaws
being arranged to reciprocate and hold a workpiece
against sa;d locating member, and means supported on
sa;d shuttle to move the jaws apart to receive, secure,
and release a workp;ece.
In the pre~erred embod;ment of this prior art, the
pallet ;s constructed so that ;t can be adjusted to
accommodate different s;zes of preforms ~workp;eces),
includ;ng means to adjustably mount the jaws so the;r
spacing can be changed and removabLy mount;ng the
locat;ng member. An annular shaped ring preferably
serves as the locating member and vert;cally locates and
centers the preform.
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A pair of sa;d jaws is provided at each locating and
support assembly~ Each jaw has a preformed engaging end
w;th a shallo~ V configuration. The other end of each
jaw has a pair of elongated slots by means of ~hich earh
jaw is adjustably secured to a slide by a pair of bolts
in tapped holes~ The slides are respectively mounted on
a pair of spaced apart ways or guides which conveniently
and preferably are circular in shape and fit into bushed
holes on their respective sides of the pallct. The
slides are biased together by a pair of helical springs
in tension. In the central part of each slide is
mounted a pair of stop buttons~ These serve as a means
to positively locate and space the guide with reference
to the locating and support assemblies or a Go-planar
surface that is part of a shuttle~
It can be seen that the jaws can be spaced as needed
by loosening the pair of bolts holding each jaw to its
respective slide. ~hen setting up the machine, locating
and support assemblies of the correct size are installed
then a preform of the correct size is ;nserted in its
proper position against the locating and support
assemblies while the jaws are being held loosely by
their respective bolts. The jaws are biased so that
their V ends engage preform and the bolts are tightened.
Actuating means comprises an assembly of levers and
cranks for transmitting mot;on to the slides and caus;ng
the slides-jaw assembLies to move apart upon command.
The command or in;tiating event is when a part of the
blow molding machine depresses the bell cranks at the
end of the shafts. When those are depressed, rotation
of the shafts spreads apart the jaws against the bias of
the various spr;ngs. Release of the force on the bell
cranks allows the same to close. This opening and
closing feature enables loading and unloading the
preforms as well as detaining same in place during blow
molding. There are a pair of shafts extending
longitudinally of the shuttle and mounte~ revolvably on
the shuttle at a plurality of journal bearings. At the
extreme ends are bell cranks with one arm extending
substantially horizontally towards the center line of
the pallet. The other arm of each bell crank as well as
levers located intermediately along the respective
shafts engage each slide adjacent one end thereof so
that there are a pair of levers (or bell crank arms)
operating each slide. The bell cranks may comprise a
pair of levers secured at about right angles on the
shelf.
The present invention is an improvement in reheat
blow molding injection molded thermoplastic preforms and
provides positive and simple control of the preform upon
presenting it to the blow mold.
It is an object of -the present invention to provide
an effective and reliable pallet assembly capable of
accurately locating and supporting a preform in a
desired manner using a structure, which is economical,
simple and reliable, to resiliently grip the neck of the
preform.
The present invention does not include the
peripheral equipment such as the oven; means to
transport from the oven to the pallet; pallet loading or
unloading means; or the mold design. The present
invention relates to a pallet assembly for conveying
substantially horizontally a plurality of workpieces
each having a circular cross-section from one location
through a manufacturing operation to another location
comprising the assembly of: an elongate pallet shut-tle
constituting a base on which the other members of the
assembly are mounted; a plurality of workpiece
supporting and locating assemblies supported
longitudinally on said shuttle, each of said assemblies
further comprising: a workpiece support and locating
means having resilient means comprising a plurality of
spaced apar~ spring members, each said spring member
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having a generally vertically extending elongate planar
spring por-tion and a looped end for engaging said
workpiece, an area of each said portion, adjacent one
end thereof, being secured to said supporting means,
said looped end extending from the other end of said
portion to engage and resiliently support a workpiece
against a stop ring supported on said shuttle to
receive, vertically locate and center a workpiece with
reference to said shuttle, said ring having an aperture
therethrough and a substantially circular locating
surface for receiving and locating a matching surface on
said workpiece.
Other features of the invention will become
apparent from the detailed description, given by way of
example, when read in conjunction with the drawings,
wherein:
Fig. 1 is a partially schematic side view of a blow
molding sys-tem that uses the instant pallet assembly;
Fig. 2 is a side view of a typical injection molded
preform as contemplated for use in the present
invention.
Fig. 3 is a under view of the pallet assembly;
Fig. 4 is a side elevation of the pallet assembly
of Fig. 3;
Fig. 5 is a sectional elevation of a preform
locating and support assembly, four of which are
attached to the pallet assembly illustrated in Figs. 3
and 4; and
Fig. 6 is an exploded view illustrating the
components of the locating and support assembly of
Fig. 5.
The preform 1 (Fig. 2) is of injection molded
thermoplastic biaxially orientable material which will
so orient upon being blown in a mold at a certain
temperature after release from the instant pallet. For
example, polyethylene terephthalate orients in the range
from about 200 F to 250 F. It has a hollow body
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253 shaped like a test tube with an externally threaded
lip 4 above a support ring 6. The space 8 between the
lip and ring 6 provides an annular groove by which the
present pallet grips the preform and provides positive
control.
The preform is not blow molded in the region of
threads and rings 4, 6 hence it is not heated in such
region. For this reason the preform is handled (e.g.
Fig. 2) and gripped in this region until the blow
molding has been accomplished.
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The pallet assembly 9 (Fi~s. 3, 4) has sev2ral
components each of which bears further d;scussion: the
palle~ base or shuttle 10 on which the other components
are mounted; locator means 12 comprises a plurality of
shot pin bushings of hardened steel having a tapered
hole 13 therein and a plurality of locating and support
assemblies 15 for vertically locat;ng and hor;zontally
centering the preforms.
The pallet shuttle 10 is preferably a casting and is
the base on which the other elements are mounted. The
pallet 10 is machined as needed so that the other
components can be fitted and supported properly on the
base. The pallet connects to adjacent pallets by means
of a plural;ty of latches Z2 which are bolted in pairs
on end tab 24 that are integral and e~tend
longitudinally from the main body of the shuttle. Each
of these latches has a locking head and recess 25, 26 to
enable connection with mating means similarly shaped on
an adjacent shuttle as illustrated in fig. 1. To
accomplish this with a minimum diversity of parts, all
of the latches are made alike and they are mounted with
the recess facing down at one end (to the right in Fig.
4) and mounted ~ith the recess facing up (left in Fig.
4). The way that the latches work is to move additional
shuttle assemblies perpendicular to the plane of the.
platen as viewed in F;g. 1 thereby to cause the
latchhead and recess on adjacent units to engage. A
similar motion perpendicular to the plane of the paper
disengages. Engagement and disengagement is achieved
without the use of moving latch parts.
Viewed in longitudinal cross-section, the shuttle 10
resembles an H beam with a series of bosses and
apertures. The flanges of the beam are preferably
shaped to form rails 30 for engagement ~ith supporting
structure or pallets as the case may be. One side of
the shuttle has a longitudinal slot into wh;ch is fitted
a female bearing rnember having a groove~ Preferably the
bearing member ;s made of fabr;c ~hat ;s ;mpregnated
with a thermoset resin such as phenol formaldahyde
resin~ The bear;ng member likew;se has a groove ;n ;t
for engagement with adjacent machine elements such as a
rail on pallets or the table or o~her member which
supports the pallets.
The other flange of the shuttle or base contains a
1~ male bear;ng member in the form of a projecting rail
that extends longitudinally of the entire shuttle.
Preferably, th;s male member is of a size or profile
that it could sit ;nto the groove formed in the bearings
should it be desired to next pallets longitudinally next
to each other.
The locator means 12 are a plurality of pushings
having a tapered hole 13 therein. These means are to
permit positive location of the pallet relative ~o
adjacent machines by the insertion of a mat;n~ shot pin
~, into the tapered hole as d;scussed elsewhere ~J;th
reference to Fig. 1. Positive location requ;res at
least two of these locator means but three are shown ;n
the preferred construction. The bushing 1~ is secured
to the web of the shuttle by a pair of bolts~ The
bushings should all be located on the center line of.the
locating and support assemblies 15.
The locating and support assemblies 15 are for
vertically locating and horizontally centering the
preforms by providing an internal shoulder 44 that
engages a correspondingly shaped shoulder on the upper
side of support rings 6 on th,e preformr Where it is
contemplated that the pallet may have to handle preforms
with support rings 6 of respectively widely varying
dimensions, a different locating and support assembly
with a different dimension must be provided for each
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size to be handled at each station where a preform is to
be engaged. As illustra~ed, there would have to be four
locating and support assemblies of each s;ze
contemplated. The locating and support assemblies are
respectively bolted firmly to the underside of the
shuttle by four bolts 45. An aperture 46 extends
completely through the rin~ and is substant;ally ;n
register with a hole through the web of the shuttle.
The locating and support assembly also supports
resilient fingers 18 that engage the preform.
Each loca~ing and support assembly 15 (see Figs. 5
6) has a gripper spring support ring 50 defining a
circular opening 51 to receive the lip ~ of a preform,
and gripper spring locating and support surfaces 52 to
locate and support four preform gripper springs 53 in a
symmetrical circular array around the opening 51 to
position looped ends 54 of the springs 53 to resiliently
engage the aforementioned annular groove of the preform,
when the preform is in the openina 519 thereby to locate
and support ~he preform relative to assembly 150 Each
spring 53 is fixedly mounted to the ring 50 by two
screws 55 for deformation independently of the other
springs 53.
The assembly 15 also has an assembly mounting plate
56 by ~hich the assembly is bolted by bolts 45 to the
platen 10. Plate 56 defines a central opening 57
dimensioned and shaped to locate and support ring 50
therein between an annular flange 58, which defines an
opening, coaxial with opening 51, and a clamp plate 59
~olts 45 extend through the clamp plate 59 and plate 5
to platen 10.
The clamp plate has an inwardly extend;ng annular
flange or StQp ring 44, defining an opening to permit
lip 4 of a preform to pass therethrough into the ring
50. The flange 44 is dimensioned to engage support ring
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of a preform ~o locate the preform axially of the
assembly 15 (axially being along the axis of the opening
51), and thereby o~ the pallet 10, in resilient
engagement with the spr;ngs 53.
S It w;Ll be appreciated that the particular structure
described for the assembly 15 is not lim;ting and that
the present ;nvention encompasses other resilient
structures utiliz;ng independently deformable springs
adapted to engage the preform in the des;red manner
described. Such structures including, for example,
annular springs to directly engage the preform and
spring arrangements located to cause detents or buffer
members to engage a preform as desired~ Many similar
structures fall within the present invention as will be
apparent to a man skilled in the art.
Fig. 1 shows the environment in which the pallet ~
may be and pre~erably is used. Many of the details are
omitted inasmuch as they are already kno~n and are no
part of the present invention, indeed some having
different inventors.
Fig. 1 illustrates the three most ;mportant stat;ons
of the operat;on wherein the pallet is used. These are
the left of Fig. 1, a loading station ~0 using a
so-called picker to pull preforms 1 up into the pallet,
a blo~ molding station, and then a discharge or ejection
station.
The preforms 1 are delivered underneath the pallet
after being heated to a predetermined temperature in an
oven. A machine called a picker 81 is located above the
pallet uhich is to be loaded. The picker heads ~7 is
driven to reciprocate vertically and ;s driven down into
each preform to engage it. The picker head ;s basically
a cylindrical member hav;ng at its end 88 an O ring
around its circumference. The 0-ring has a compression
fit with the inside of the preform in the neck reg;on.
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The reciprocating action of the picker drives the
plunger down into compression engagement as aforesaid
and then reciprocates the picker head with preform
attached up into the pallet.
The pi~ker machine comprises a slide member 89
arranged on ways 90 and reciprocated verticalLy by a
rotary actuator 92 which preferably comprises a
hydraulic motor turning a crank arm, the end of which
works in a slot 93.
The slide 89 has mounted on it a plurality of picker
heads 87 -illustrated in Fig. 1 as four in number--but
;n any event corresponding in number to the numbers of
preforms to be pulled up ;nto the shuttle. The p;cker
heads are spring b;ased to their position so that slight
overrides at the ends of their stroke are taken up by th
springs 95 at the ends.
A pair of spaced apart shot p;ns 40 engage the
locator means~ The shot pins are likewise biased as by
springs 96 to their positions.
When the rotary actuator drives the slide~ the
picker heads 87 proceed on through the apertures in the
pallet to engage the neck of the respect;ve preforms
while at the same time the shot plns 40 have engaged
their tapered recesses 13 in the pallet. On the return
stroke, the slide 89 moves up carry;ng with it aLl tbe
preforms 1 until the latter engage the locating and
support assemblies (preforms shouLder 6 engages shoulder
44) where they are wiped off the end of the picker
head. 9efore release from the picker head, however, the
preform is brought into locating support engagement with
the springs 53~
After the pallet is loaded, it is moved mechanically
~the preferred way) or manually to the blow molding
station 83. The preforms are moved in a f;le bet~een
open mold halves 95 the pallet 9 is stoppPd, the mold
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haLves are closed and the blowing operation takes
place. After blowing, the molds 95 are opened and the
pallet is once again moved (to the right of Fig. 1) to
this time carry the blown product out of the mold to the
eject positîon shown at the right of F;g. 1. In this
position the blown product is mechanically moved axially
of assembly 15 to release the product from the assembly
so that it can drop away from the pallet 10. This is
achieved by mechanicaLly actuated push rods 96 with
resilient members (not shown) in series therewith.
These rods 96 are moved downward to engage the neck of
the product to put thjis neck through the spring support
of springs 53 so that the product drops free. The
pallet is then unhooked at 22 and moved around to the
lS beginning station 80 where the procedure is repeated.
As previously explained, the pallet can be lcaded and
the pallet from`which bottles are to be ejected can be
moved at right angles to the plane of Fig. 1. For this
reason the latch 22, 25, 26 at the end of each pallet is
constructed at it is to permit such motion while at the
same time providing a "train" of pallets that moves from
loading to blowing to unloading.
