Multiple station, multiple clamp assembly blow molding machines

A multiple station, multiple clamp assembly rotary blow molding machine for the manufacture of plastic bottles and the like incorporating novel toggle actuation means for the clamp assemblies, novel actuation means for the pre-finish mechanism and novel actuation means for parison stretching. The novel toggle actuation means for the clamp assemblies eliminate the need for separate linear or rotary hydraulically driven clamp actuators for each clamp assembly. Rather, a single rotary actuator is required for the mold closing station and a second single rotary actuator is required for the mold opening station. The toggle linkage includes adjustment means for fine adjusting the length of each toggle linkage. The clamp assemblies include spring means for assuring complete overcentering action of the toggle linkages to thereby provide a positive latching or locking of the clamp assemblies and molds in the closed position.

BACKGROUND OF THE INVENTION 
The invention pertains to multiple station, multiple clamp assembly blow 
molding machines for the manufacture of bottles and the like. In 
particular, the invention pertains to various improvements in mechanisms 
for clamping the molds together, stretching the extruded parison and 
pre-finishing the bottle at the opening thereof. 
Multiple station blow molding machines are usually of circular or rotary 
configuration wherein the machine comprises a plurality of stations 
located about a circular path. Usually the machine includes a plurality of 
clamp assemblies, each containing a mold for one or more bottles. The 
total number of clamp assemblies usually equals the total number of 
stations. The clamp assemblies rotate from station to station about the 
circular path with various operations taking place either at the various 
stations which are of fixed location, or during movement between stations. 
In a typical machine each clamp assembly requires a mechanism for closing 
and opening the clamp assembly to thereby close and open the mold therein 
and means to assure that the mold remains tightly clamped together during 
the blowing and prefinishing stages of making the bottle. Modern machines 
typically use a cam or hydraulic pressure mechanism for opening and 
closing the clamp assembly with cam action or hydraulic pressure providing 
for tight closure at the end of the closing stroke. A hydraulic or other 
actuator is attached to each clamp assembly and moves with the clamp 
assembly about the circular path of the machine. Such a machine therefore 
requires a separate actuator for each clamp assembly and means to supply 
hydraulic power to the actuator as it moves about the circular path. 
The toggle action clamp assembly locks the molds tightly together at the 
end of the toggle linkage stroke. The hydraulic actuator is continuously 
pressurized to assure that the molds remain tightly joined until blowing 
and pre-finishing are completed and the bottle is ready to be ejected from 
the mold. 
Pre-finish devices for blow molding machines-typically are combined with 
the blow pin assembly, either of which or both, may be moveable 
vertically. The vertical movement is actuated by a cam or a crank 
mechanism at the appropriate moment during the blow molding cycle. The cam 
mechanism is extensive in length and complicated to manufacture because 
the entire clamp assembly supporting the blow pin and pre-finish unit 
moves relative to the cam, the cam being fixed to the base of the machine. 
Stretching means for stretching the lower end of a parison into an oblong 
shape also require a complicated mechanism. The stretching means are 
actuated with a mechanism separate from the support that carries the 
stretching means on a moveable clamp assembly. The stretching means 
usually comprises a single upwardly extending pin spaced from a blow pin 
pre-finish unit. The single pin and blow pin of the stretching means are 
actuated to move in opposite directions at appropriate moments in the 
machine cycle and therefore are typically cam operated. Thus, a 
complicated actuation mechanism is required for stretching means that are 
mounted on a machine which moves the bottle blowing apparatus, clamp 
assembly and molds from station to station about the machine. Applicant's 
invention disclosed below is directed to improved and more effective 
mechanisms incorporated in a multi station, multi clamp assembly blow 
molding machine. 
SUMMARY OF THE INVENTION 
The invention comprises an improved multiple station, multiple clamp 
assembly blow molding machine for the manufacture of plastic bottles and 
other similar articles. More specifically, the invention is directed to 
various features which provide a more effective, less expensive blow 
molding machine. 
Each of the clamp assemblies is provided with a toggle linkage assembly 
that is actuated by a crankshaft. The crankshaft in turn includes means 
that are engageable with a hydraulic rotary actuator. Hydraulic actuators, 
however, are provided only at those stations, normally two, that require 
the clamp assembly to be opened or closed. At other stations between 
closing and opening and during indexing between the stations, the toggle 
linkage is effectively locked and the crankshaft prevented from rotating 
thereby preventing release of the clamp assembly. Within the clamp 
assembly and toggle linkage assembly, means are provided for fine 
adjusting the length of the toggle linkages individually. Resilient 
springs means are incorporated for overcentering of the toggle linkages to 
provide positive latching or locking when the clamp assembly is closed. 
The positive latching or locking feature eliminates the need for a 
hydraulic actuator on each clamp assembly and moveable therewith. 
Adjacent and attached to each clamp assembly and extending upwardly in 
between the clamping platens is a combined blow pin pre-finish unit. The 
blow pin pre-finish unit is moveable upwardly and downwardly to pre-finish 
the open end of the bottle as it is blown. The motion of the pre-finish 
unit and blow pin is actuated by a relatively short horizontally moveable 
cam. The cam engages a follower which in turn is directly attached to the 
blow pin pre-finish unit. The cam rides on a horizontal track suspended 
beneath the blow pin pre-finish unit. The track, being attached to the 
blow pin pre-finish assembly and a part thereof, moves with the clamp 
assembly from station to station about the machine. A second follower 
extends downwardly from the cam and is adapted to engage second cams fixed 
to the machine base at appropriate locations adjacent stations so as to 
move the first cam horizontally on the track as the clamp assembly passes 
by. The cam is shaped with a central ascending-descending portion leading 
to horizontal dwell portions on either side thereof. The follower attached 
to the blow pin pre-finish unit and driven by the first cam, remains in 
one of the dwell portions of the first cam unless the first cam is moved 
by the second cam. Thus, the cams utilized for actuating the pre-finish 
unit are very short and simple in configuration. 
The stretching means incorporates the pre-finish blow pin assembly as one 
of the two upwardly extending stretch pins. The entire stretching means 
moves with the clamp assembly from station to station. The blow pin 
pre-finish assembly and the separate stretch pin are both supported on a 
pair of parallel horizontally moveable rods. Each of the rods include a 
rack formed thereon and engageable with a single pinion gear therebetween. 
Rotation of the pinion gear causes the rods to move in opposite 
directions. The blow pin pre-finish assembly is attached to one rod and 
slidably supported on the other rod whereas the separate upwardly 
extending stretch pin is attached to the other rod and slidably supported 
on the first rod. Thus, as the parallel rods move, the stretch means move 
in opposite directions. The pinion gear is mounted on a vertical shaft 
having a crank and a follower on the crank. The follower is engageable by 
a cam attached to a movable platen adjacent the mold. Mold closure engages 
the cam with the follower thereby rotating the crank and pinion gear to 
extend the stretching means. Fixedly mounted on the machine base is a 
fixed cam engaged when the clamp assembly and stretch means move past the 
cam. The fixed cam causes the stretching means to retract. The stretching 
means cam, however, is mounted on the platen in a manner that allows the 
horizontal position of the cam to be selectably adjusted. The horizontal 
position of the cam controls the rotational angle through which the crank 
turns and the pinion gear turns, thereby determining the stroke of the 
stretch means.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 and 2 illustrate a five station, five clamp assembly machine. The 
five stations are identified by the Roman numerals I through V. The five 
stations, I through V, are fixed locations on the machine. As shown in 
FIG. 1 five clamp assemblies generally denoted by 20 are shown at the five 
stations. The machine is a rotary machine wherein the clamp assemblies 
affixed to a table 21 rotate among the five stations in sequence about the 
center pivot 22. The rotation is intermittent wherein the clamp assemblies 
dwell at the stations and then simultaneously index therebetween. As 
shown, the clamp assemblies 20 are open at stations I and V and closed at 
stations II through IV. In actual operation station I is the clamp 
assembly close station wherein the molds contained within the clamp 
assembly are closed about an extruding parison. 
Referring to FIG. 16 the timing sequence chart for the machine of FIG. 1 is 
illustrated. As a clamp assembly leaves dwell station I and indexes 
through dwell station II and into dwell station III the bottle is blown. 
Upon indexing from station III the bottle is exhausted and the clamp 
assembly 20 opened. Simultaneous with the opening of the clamp assembly 20 
in dwell station IV automatic unloading apparatus (not shown) grasps the 
bottle and unloads the bottle from the machine. 
Station V of the machine is provided for preparation of the mold before the 
mold indexes to dwell station I and the cycle repeats. In this particular 
machine in-mold labeling may be provided at dwell station V as an example. 
(The in-mold labeling apparatus is not shown.) 
FIG. 2 illustrates schematically the machine at stations II and V taken in 
the direction of the arrows 2 in FIG. 1. The clamp assemblies 20 rotate 
about the central pivot 22 here shown in FIG. 2 as a central support 24. 
The central support 24 supports a guide plate 26 which in turn supports 
the mold close actuator assembly generally denoted 28 and two rotary 
hydraulic actuators 30 and 32, shown in FIG. 1. 
FIGS. 3, 4 and 5 illustrate in more detail the construction of a single 
clamp assembly 20. The clamp assembly comprises two platens 50 and 52 for 
supporting the two halves of a bottle mold or the like (not shown). A 
third platen 54 is positioned between the platen 50 and the toggle linkage 
generally denoted by 36. Two of the platens 50 and 54 are slidable on 
rails 58 on either side of the clamp assembly and affixed to the rotatable 
machine table 21. Platen 52 similarily engages rails 60 on either side of 
the clamp assembly, the rails 60 being affixed to the rotatable machine 
table 21. A pair of steel rods 62 and 64 are affixed at either end to the 
platens 52 and 54. The steel rods 62 and 64 pass slidably through bearings 
66 inserted in holes in the platen 50, thus the platens 52 and 54 move 
together with the platen 52 moveable toward and away from the platen 50. 
The platen 50 moves in opposition to the platen 52. All three of the 
platens are retained in alignment by the rods 62 and 64 and the rails 58 
and 60. As shown, the rods 62 and 64 are shouldered 63 near each end and 
are tightly fastened to the platen 54 by nuts 70. At the opposite end, 
Belleville washers 68 are inserted between the platen 52 on each rod and 
the retaining nut 70 on each rod to urge the platen 52 against the 
shoulders 63. The Belleville washers 68 provide a slight flexibility in 
the distance between the platens 52 and 54 or between the platens 52 and 
50 when the molds (not shown) close tightly. 
The toggle linkage assembly 36 comprises separate toggles for the platen 50 
and the platen pair 52 and 54. The platen 50 is actuated by identical 
upper and lower toggle links 72 each attached pivotably by vertical pins 
74 to threaded eye studs 76 in turn attached to the platen 54. At the 
opposite end of toggle links 72 are vertical pivot pins 78 providing 
engagement with a pair of cranks 80 on a vertical crankshaft 82. Toggle 
link 84, located vertically between the pair of toggle links 72, is 
pivotably attached by a vertical pin 86 to a threaded eye stud 88 in turn 
attached to platen 50. Toggle link 84 is at the other end pivotably 
attached by a vertical pin 90 to a crank 92 also on the vertical shaft 82. 
Viewed from above, clockwise rotation of the vertical crankshaft 82 causes 
the link 84 to move the platen 50 toward the platen 52 and causes the 
links 72 to pull the platen pair 54 and 52 in the opposite direction. Full 
180 degree rotation of the crank 82 clockwise causes the toggle linkages 
to center and fully shut the two platens 50 and 52 with the mold 
therebetween tightly closed. Because it is critical that the toggle 
slightly overcenter with the molds shut tight to assure that the molds 
remain tight under blowing conditions, the molds must typically be very 
accurately manufactured. 
The clamp assembly 20 shown in FIGS. 3, 4 and 5 contains two features to 
assure that the molds clamp tightly together without the extreme accuracy 
requirement normally needed for proper overcentering of the toggle 
assembly. Firstly, the Belleville washers 68 permit molds that are 
slightly off size to be accommodated without damage or excessive wear to 
the toggle linkages. Secondly, each of the threaded eye studs 76 and 88 is 
affixed to the respective platens 54 and 50 by threaded slip ring clamp 
assemblies 92 in turn affixed to the respective platens. It may be noted 
that the platen 54 includes a hole 94 which permits the link 84 vertical 
pin 86 and threaded eye stud 88 to move therethrough. 
At the top of the crankshaft 82 is a rotatable disk 38 threadably affixed 
or splined to the crankshaft. The rotatable disk 38 in turn has affixed 
thereto a pair of followers 40 and 42 which engage the rotary hydraulic 
actuators 30 and 32 shown in FIG. 1. The vertical crankshaft 82 is 
supported in bearings 96 in turn located in bearing supports 98 affixed to 
the main rotatable table 21 of the machine. 
Each clamp assembly 20 is connected through its respective toggle linkage 
to its rotatable disk 38 and the two upstanding followers 40 and 42 
located on the disk 38, 180 degrees apart. The rotary hydraulic actuators 
30 and 32 through their respective couplings at stations I and IV are 
engageable with the followers 40 and 42 to rotate the disk 38, 180 
degrees. Viewing from above at station I the plate 38 is rotated 180 
degrees clockwise by the rotary actuator 32 to close the clamp assembly 
20. At station IV the plate 38 is rotated 180 degrees counter-clockwise by 
the rotary actuator 30 to open the clamp assembly 20. 
As shown in FIGS. 6, 7 and 8 the mold close actuator assembly 28 is 
positioned atop the guide plate 26 in turn fastened to the central support 
24. The mold close actuator assembly 28 includes a central vertically 
moveable actuator support 23 having the pair of rotary hydraulic actuators 
30 and 32 affixed to either side. The actuator support 23 is vertically 
moved by a hydraulic cylinder 25 located therebelow in a guide support 27. 
The guide support in turn retains two vertical pins 29 and 31 which extend 
through guide bushings 33 in the actuator support 23. A central alignment 
shaft 35 also extends through a bushing 37 in the actuator support 23. 
Thus, actuation of the hydraulic cylinder raises and lowers the rotary 
actuators 30 and 32. 
Each rotary actuator 30 or 32 has a vertical shaft 39 attached to a flange 
41 in turn attached to an engagement plate 34. The engagement plate 34 
includes a curved sided channel 43 formed in the underside thereof for the 
engagement of the followers 40 and 42 of each disk 38. With engagement 
rotary movement of the shaft 39 causes rotation of the crank 82 and 
opening or closing of the clamp assembly 20. 
The combination of the curved side channels 43 in the engagement plates 34 
and the vertically moveable actuator assembly 28 provides a redundant 
means to prevent improper engagement. In normal operation the hydraulic 
cylinder 25 raises the rotary actuators 30 and 32 and the engagement 
plates 34 to completely clear the followers 40 and 42 as the clamp 
assembly 20 rotates into the dwell station. Then, the actuator assembly is 
lowered and the followers 40 and 42 are engaged by the channel 43. In the 
event that the actuator assembly 28 fails to raise, the curved sides of 
the channel 43 permit the followers 40 and 42 to move through the channel 
43 without damage and the machine to continue to operate. 
FIG. 7A details the shape and operation of the guide plate 26. To avoid 
opening or closing of the clamp assemblies 20 at other stations and during 
indexing therebetween and to permit closing or opening of the clamp 
assemblies at stations I and IV respectively, the substantially circular 
guide plate 26 is axially fixed to the machine. The followers 40 and 42 
engage the outside perimeter of the plate 26 as shown except at the two 
concavities 46 at station I and 48 at station IV. Thus, only at stations I 
and IV can the clamp assemblies be actuated to either close or open, the 
clamp assemblies 20 being otherwise additionally latched by the engagement 
of the followers 40 and 42 with the plate 26. This latching prevents 
inadvertent actuation of the toggle linkages generally denoted 36 which 
provide the tight overcenter latching of the clamp assemblies. 
FIG. 7B details the actuator stop means for rotary actuator 32. Extending 
from the guide support 27 is bracket 44 retaining fixed stop pins 45. 
Extending integrally from the engagement plate 34 is a partial flange 47 
retaining stop pins 49. The stop pins 49 move with the plate 34 to limit 
the rotary motion of the plate 34 to 180.degree. by means of engagement 
with the fixed stop pins 45. 
The rotary blow molding machine can be equipped with a variety of blowing 
and pre-finishing means depending upon the number of cavities in the mold 
and configuration of the products. Illustrated in FIGS. 9, 10 and 11 are a 
pair of blow pin pre-finish units for a dual cavity mold. Shown ghosted in 
FIG. 9 is the pair of platens 50 and 52 and mold halves 100 and 102 
clamped tightly shut about a parison within a mold cavity 104. Within the 
mold cavity is the blow pin 106 comprising a hollow tube supplied with air 
or nitrogen as desired under pressure for expanding the parison into the 
mold cavity 104. The blow pin 106 is affixed to and supported on a 
pre-finish unit 108 inserted up into the lower opening 110 of the mold 
cavity 104. 
The blow pin and pre-finish unit are supported with adjustable threaded 
means at 112 in a vertically moveable tubular support 114 in turn carried 
within slidable bearings 116 in a support collar 118. The collar 118 in 
turn is affixed to a cross plate 119 mounted on the rotatable table 21. 
Suspended below each blow pin pre-finish unit is a horizontal track 120 
also affixed to the cross plate 119 by vertical supports 122. Moveable 
horizontally on the track 120 is a cam block 124 having a cam path 126 
formed in one side thereof. In engagement with the cam path 126 is a 
follower 128 in turn attached to the vertical support tube 114. Thus, 
movement of the cam block 124 back and forth on the track 120 causes the 
follower 128 and vertical support tube 114 to move vertically thereby 
causing the pre-finish unit and blow pin to move vertically. The shape of 
the cam path 126 provides an ascending-descending central section 130 
between upper 132 and lower 134 dwell regions. 
Extending below each cam block 124 is a second follower 136 adapted to be 
engaged by a second cam path 123 on a cam 125 affixed to the machine bed 
as shown in FIG. 17. As the rotatable table 21 carrying the clamp 
assemblies indexes from station I to station II, the followers 136 engage 
the second cam path 123 thereby causing the cam blocks 124 to shift from 
the one dwell region 134 to the other dwell region 132 and, in turn, 
thereby raising the pre-finish units and blow pins 106. 
Typically, only two second cam paths 123 and 127 affixed to the machine bed 
will be located on the machine, one to cause a raising of the pre-finish 
and blow pin units and the other to cause a lowering of the pre-finish and 
blow pin units. The second cam path 127 is located on cam 129 between 
stations IV and V for lowering of the pre-finish and blow pin units at the 
timing position 140 illustrated in FIG. 16. 
As shown in FIGS. 17 and 18 each of the cams 125 and 129 is attached by a 
vertical pinot 131 to a bracket 133 on the machine base. At the other end 
135 of each cam 125 and 129 an air cylinder 137 is pivotally attached, the 
air cylinder in turn being pivotally attached 139 to a bracket 141 on the 
machine base. 
The cam block and track actuation means for the blow pin and pre-finish 
units illustrated in FIGS. 9, 10, 11, 17 and 18 provides very short cams 
with a very short paths for actuating the units. The short cam with the 
dwell regions 132 and 134 and ascending-descending region 130 provides a 
simple and very economical mechanism for the prefinish and blow pin unit 
and eliminates the need for extension camming surfaces on the machine to 
control the movement of the pre-finish units. 
As an alternative to the dual blow pin and pre-finish units shown in FIGS. 
9, 10 and 11, FIGS. 12, 13, 14 and 15 illustrate a dual blow pin and 
pre-finish unit in combination with stretching means wherein the lower end 
of the extruding parison is stretched to an oblong shape as the mold 
halves close about the parison. The mechanism is supported on the rotary 
table 21 and moves with the clamp assemblies and platens 50 and 52 which 
hold the mold halves. In this particular embodiment, the pre-finish units 
108 and blow pins 106 are again threadably mounted 112 on a tubular 
support 114 for vertical movement and cam actuation with moveable cam 
blocks 124 as disclosed above. The tubular supports are slidably mounted 
in bearings 116 in turn supported by cross blocks 142 each having a pair 
of horizontal holes 144 therethrough. 
Passing through the holes 144 and supporting the blocks 142 are a pair of 
rods 146 and 148. The rods 146 and 148 are supported at one end in 
slidable bearings 150 in turn supported on the machine table 21 and rail 
by a bracket 152. At the other end of the rods 146 and 148, a second 
bracket 154, also supported on the rotatable table 21 and other rail, 
slidably supports the rods for independent axial movement. A pair of 
second blocks 156, by means of parallel holes 144, are also supported on 
the pair of rods 146 and 148. 
Blocks 156 have stretch pins 158 extending upwardly therefrom. Blocks 156 
are split at 160 and include screw means at 162 for tightly affixing 
blocks 156 to rod 146. Blocks 156, however, are slidably supported 149 on 
the rod 148. In turn, blocks 142 are split adjacent rod 148 and affixed 
thereto by screws at 164. Blocks 142 are slidably supported 149 on rod 
146, thus blocks 142 move with rod 148 and blocks 156 move with rod 146. 
Located within bracket 154 on a pair of bearings 166 is a vertical shaft 
168. The vertical shaft 168 supports a pinion gear 170 between and 
engaging racks 151 on each rod 146 and 148, thus, rotation of the shaft 
168 and pinion 170 causes axial movement in opposite directions of the 
rods 146 and 148. Opposed axial motion of the rods 146 and 148 causes the 
blocks 142 and 156 to move in opposite directions. Movement of blocks 142 
and 156 apart provides the stretching movement. As shown, the stretching 
means is fully extended. The opposite movement of blocks 142 and 156 
retracts the stretching means. 
At the upper and lower ends of the shaft 168 are attached cranks 172 and 
174. Each crank 172 and 174 is equipped with upper and lower followers 176 
and 178 respectively. Affixed to platen 50 is a bracket assembly and 
support 179 for an extension cam 180. Upon closing movement of the platen 
50 at station I the extension cam 180 engages the follower 176 causing the 
crank 172 and shaft 168 to be rotated, in turn causing the stretching 
means to extend. 
The amount of extension is adjustable by the horizontal position of the cam 
180 that is selected. The cam 180 is slidably moveable on a supporting 
track 182 affixed to the bracket assembly and support 179. Adjustment 
screws 184 provide the horizontal adjustment of the cam 180. 
In a similar manner the lower follower 178 engages a retraction cam 181 
which causes retraction of the stretching means. The retraction cam, 
however, is affixed to the machine base by a bracket 183 as shown in FIG. 
17 for engagement with follower 178 during indexing movement from stations 
IV to station V. The locations for extension and retraction of the 
stretching means are given on the sequence chart FIG. 16 at 186 and 188. 
Leftward adjustment of the cam 180 by the screws 184 reduces the total 
stretching stroke whereas rightward adjustment of the cam 180 increases 
the stretching stroke. As before, the actual extension and retraction cams 
installed on the machine to actuate the stretching mechanism are very 
short relative to the entire movement of the mechanism about the machine 
and only two in number, one to cause extension of the stretching means and 
one to cause retraction of the stretching means. 
In FIG. 16 the sequence chart for the rotary blow molding machine 
illustrates the various operations that occur at each of the dwell 
stations I through V and the indexing motion therebetween. the "Extruder 
Motion" refers to the single or double vertical parison extruders located 
above dwell station I. A suitable vertical extruder is disclosed in the 
applicant's co-pending U.S. application Ser. No. 592,518. The "Die Gap 
Close" refers to the full closure of the extrusion die by the mandrel 
therein thereby severing the parison from the extruder. 
The "Stretch" refers to the stretch means disclosed above when included in 
the machine. Typically, a parison is stretched into an oblong 
cross-section just prior to mold closure where the final product includes 
a handle or is substantially oblong in cross-section. 
The sequence chart is illustrative only. The actual timing of each 
operation at a dwell station is partially dependent on the particular 
plastic material extruded and the mold configuration. Station V is 
included for in-mold-labelling or other operation to prepare the mold for 
the next parison at station I.