Anti-rotation device for capping machine

A device and method of preventing rotation of a plastic container of the type having a generally cylindrical body, a circular flange below a threaded neck and a pedaloid base with pads separated by diverging recesses as a capping head screws a cap onto the neck while the capping head and container are moving in unison along a preselected path, which device method comprises a support member with an upwardly extending, fixed rib extending along the path whereby the container slides along the rib as it is moved with the capping head so the rib extends into a recess of the pedaloid base to prevent rotation of the container with the capping head.

The present invention relates to the art of capping plastic bottles or 
containers as they are moved along a preselected path and more 
particularly to an improvement in a capping machine which prevents 
rotation of the plastic bottle while a cap is being tightened onto the 
neck of the bottle. 
The invention is particularly applicable to assembly of a plastic cap onto 
a plastic bottle of the type having a pedaloid base constituting a 
plurality of protruding pads separated by diverging recesses or crevices. 
However the invention has much broader applications and can be used in 
applying a cap onto a bottle which has various protrusions on its base. 
INCORPORATION BY REFERENCE 
Peronek U.S. Pat. No. 4,939,890 describes a capping machine of the type to 
which the present invention is directed, together with a description of 
several arrangements used in the art for preventing rotation of the bottle 
as it is being capped during its rotary movement by a star wheel. This 
patent is incorporated by reference herein as background information to 
explain the prior anti-rotation arrangements of which the present 
invention is a specific improvement. Consequently, the details of the 
capping machine of the type to which the present invention is directed 
need not be explained. 
BACKGROUND OF INVENTION 
A capping machine or conventional capping apparatus includes a star wheel 
rotatable about a machine axis and having a plurality of outwardly opening 
pockets adapted to receive bottles fed in an assembly line fashion to the 
star wheel. Overlying the rotating star wheel is a plurality of individual 
capper heads for use in applying a cap to the upper threaded neck of a 
plastic bottle carried by the star wheel in an arcuate path centered about 
the machine axis. A turret rotates the star wheel and capping heads in 
synchronism about the machine axis with an individual capping head located 
directly above each bottle receiving pocket on the star wheel. The capper 
heads employ a clutch mechanism whereby the head carrying a cap is rotated 
and driven axially downwardly at a predetermined force and torque limiting 
value to tighten the cap onto the bottle neck. In accordance with standard 
practice, an entrant guide mechanism is mated with the capper star wheel 
to feed filled bottles to an entry point on the path of movement of the 
capper star wheel. An exit guide mechanism is similarly mated to the 
capper star wheel to transfer the capped bottles from an exit point of the 
rotating capper star wheel. A stationary rear guide plate extends 
generally between the entry and exit points on the capping machine and is 
spaced radially outwardly from the pockets of the star wheel and functions 
to retain the bottles in the pockets as the star wheel rotates in unison 
with the capping heads. This is a conventional capping machine employed in 
bottling plants and is the mechanism to which the present invention is 
directed. 
During the capping operation, it is necessary to assure that the bottle 
does not spin as the cap is tightened. A spinning action during the 
capping procedure can cause damage to the plastic container and reduce the 
desired tightness of the cap being applied automatically to the bottle as 
it is translated in a path determined by the star wheel. In the past, 
certain cap designs required a relatively high downward force during the 
capping operation. When this occurs, spinning of the bottle is prevented 
by frictional contact with the pocket, with the rear guide plate or with 
both of these structures. As the downward force during the capping 
operation has been reduced due to the design and functional 
characteristics of the cap being applied, friction at the neck of the 
bottles has been increased either by the use of upwardly directed knife 
ridges provided in the anti-spin segment on the top of the individual star 
wheel pockets. This structure is disclosed in Peronek U.S. Pat. No. 
4,939,890. The knife ridges on the anti-spin segment on each pocket engage 
the lower surface of a circular flange at the bottom of the threaded neck 
of a plastic bottle to prevent rotation of the plastic bottle. This type 
of mechanism was not as effective as the downward force used in the 
capping operation was decreased due to the changes in design of the cap 
being applied. For that reason, the anti-rotation or anti-spin device of 
Peronek U.S. Pat. No. 4,939,890 has become the standard in the trade to 
prevent rotation of plastic bottles as they are being capped with 
relatively low downward force. This patent teaches a mechanism for 
externally applying a downward force on the body of a bottle being capped, 
which force is independent of the downward force created by the capping 
operation. This anti-spin or anti-rotation mechanism has been successful; 
however, it requires a mechanism for exerting a downward force on the 
bottle which is expensive and is dependent upon certain structural 
characteristics at the upper portion of the bottle itself. Changes in 
bottle configuration often require a new force exerting mechanism. 
The anti-rotation device of Peronek U.S. Pat. No. 4,939,890 is the most 
successful arrangement for applying plastic threaded safety caps onto the 
top of plastic bottles where the caps do not require heat to set or 
position the lower lock band around the neck of the bottle. The lock band 
of the cap simply snaps into a locking position when the capping head 
threads the cap onto the upper threaded neck of the plastic bottle. In 
this type of capping operation, the capper head exerts a downward force of 
between 15-20 pounds. This low axial force makes retention of the bottle 
from rotation within the star wheel pocket very difficult. This situation 
motivated the development and use of the anti-rotation feature disclosed 
and claimed in Peronek U.S. Pat. No. 4,939,890. The present invention 
relates to an anti-rotation mechanism to be used on a capping machine, 
which accomplishes the results of the Peronek anti-rotation arrangement, 
but does not rely upon developing downward frictional force on the top of 
the bottle during the capping operation. 
THE INVENTION 
In accordance with the present invention, there is provided a device or 
method for preventing rotation of a plastic container, or bottle, of the 
type having a generally cylindrical body with a circular flange below a 
threaded neck on the top of the bottle. The invention is particularly 
applicable for use with a plastic bottle having a pedaloid base which is 
somewhat standard in the soft drink industry. These bases include a 
plurality of downwardly extending pads, generally four or five pads, 
separated by diverging recesses. In the past, plastic bottles with 
pedaloid bases have been capped in a standard machine with a lower plate 
having a contoured recess or nest directly aligned with the capping head 
and pocket of the star wheel. In this arrangement, a plurality of 
contoured recesses matching the pedaloid base configuration are used to 
receive the bases of the bottles as the bottles are rotated by the star 
wheel. Since the bottles rest upon the lower circular plate and are held 
within a contoured nest on the plate, rotation of the bottles is prevented 
by an interference between the lower plate and the bottom or base of the 
bottle. This arrangement is completely different from the concept of 
increasing the friction at the top of the bottle or otherwise preventing 
rotation of the bottle by frictional force. Such structure is now being 
sold by AMCO Products Company under the trademark Peta Drive. The circular 
plate of this system includes a plurality of upwardly facing recesses, 
each matching the lower pedaloid base of the bottles. The bottles rest on 
the lower plate as it rotates with the star wheel. Physical interference 
prevents rotation of the individual bottles. Provision of a lower circular 
plate with machined recesses, each matching the contour of a pedaloid base 
of the plastic bottles is quite expensive. Each of the contoured recesses 
must be specially produced and accurately matched with respect to the 
pedaloid base of the bottle being processed. Consequently, each bottle 
required its own lower support plate. Indeed, when the filled bottles 
being capped are changed from a four pad pedaloid base to a five pad 
pedaloid base, a completely new plate for supporting the pedaloid bases 
must be assembled onto the machine. This arrangement for providing a plate 
rotatable with the star wheel for supporting the lower pedaloid bases of 
the bottles demands a plate which must be accurately machined for use with 
specific star wheels. This is another disadvantage of the use of a solid 
rotating plate with individual nesting recesses contoured for specific 
pedaloid base configurations. 
In accordance with the present invention, the device or method for 
preventing rotation of a plastic container of the type having a pedaloid 
base employs the use of a lower, fixed support member in the form of an 
upwardly extending arcuate rib matching the path taken by the moving 
bottles during the capping operation in a capping machine. An arrangement 
is used for mounting the support member in a position where the container 
slides along the rib itself as the container is moved around the arcuate 
path dictated by the movement of capping head and the star wheel. The rib 
extends into the lower recess of the pedaloid base of the individual 
bottle to prevent rotation of the bottle or container as the capping head 
drives the cap onto the upper threaded neck of the bottle. By using this 
construction, a lower support plate carrying the upstanding rib is fixed 
and does not rotate with the star wheel. The upwardly extending rib 
prevents rotation of the bottles during the capping operation. This use of 
a fixed rib constitutes a drastic improvement over other arrangements for 
using a lower plate to provide interference against rotation of the bottle 
by the capping head. These prior devices where movable with the star wheel 
to provide individual nests matching the bottom contour of the pedaloid 
bottles being capped in a standard capping machine. 
In accordance with another aspect of the present invention there is 
provided an improvement in a capping machine for applying a threaded cap 
onto the threaded neck of a plastic container having a generally 
cylindrical body, a circular flange below the threaded neck and pedaloid 
base with a plurality of pads separated by diverging recesses. The 
inventive improvement includes a turret rotatable about a machine axis and 
carrying a plurality of capping heads, each of which rotates a cap about a 
capping axis to apply a cap to the neck of a bottle as the capping head 
and container move in unison about the capping machine axis. A capper star 
wheel is rotated by the turret about the machine axis and has a plurality 
of arcuate nesting pockets engaging the plastic containers immediately 
below the circular flanges and a lower stabilizer with arcuate recesses 
engaging the container at its body portion. This type of capping machine 
includes a fixed guide plate with an arcuate guide surface concentric with 
the machine axis and radially spaced from the star wheel at a position 
generally diametrically opposite the nesting pocket of the star wheel. 
Consequently, containers carried by the star wheel are capped as they are 
moved along the guide surface of the fixed guide plate. The inventive 
improvement of the present invention is the provision of a container 
support member fixedly mounted on the machine below the guide plate and 
below the star wheel. This support member has an upwardly extending 
arcuate rib with a center of curvature at the machine axis and axially 
aligned in a vertical direction with the capping axis of the capping heads 
as the heads are moved in unison with the bottles or containers. Means are 
provided for locating the support member with the rib extending upwardly 
into a recess of the pedaloid base of the various containers as they slide 
along the rib by action of the star wheel as it rotates about the machine 
axis. In this manner, the arcuately configured rib is fixed below the 
fixed guide plate. The present improvement is merely a fixed rib onto 
which the bottles slides during the capping operation. The downward force 
by the capping operation can be exerted on the rib itself or on the 
surface carrying the rib. 
In accordance with another aspect of the present invention, the rib is 
provided in an arcuate plate assembled onto the support posts used to 
mount the guide plate of the capping machine. The plate carrying the rib 
is moved in a vertical direction so that the bottles moving during the 
capping operation slide on the plate, on the rib or on both the plate and 
the rib. The rib extends into the recess on the pedaloid base of the 
bottle to prevent rotation whether the bottle is resting on the rib or on 
the support plate carrying the rib. Of course, the rib could be 
intermittent or continuous and the rib could have a variety of 
constructions and/or cross sectional configurations. In practice, the rib 
has a cross section with arcuate edges and a flat top. In accordance with 
an aspect of the invention, the fixed arcuate plate and the rib aligned 
with the path of movement of the capping heads are formed from a single 
piece of metal, such as aluminum, that is milled to remove metal to a 
depth of about 1/8 inch, thus leaving the rib with a height of 
approximately 1/8 inch. This procedure has been found to be advantageous 
in the production of a relatively small arcuately extending rib on the top 
of a support plate to be mounted under the fixed back guide plate of a 
capping machine. 
The primary object of the present invention is the provision of an 
anti-rotation or an anti-spin device and method for use in a standard 
capping machine, which device and method prevent rotation of plastic 
bottles being capped by engaging a structural characteristic on the bottom 
of the bottle as it moves through the capping machine. 
Another object of the present invention is the provision of a device and 
method, as defined above, which device and method utilizes a member which 
is fixed and does not rotate with the star wheel of the capping machine. 
Still a further object of the present invention is the provision of a 
device and method, as defined above, which device and method can 
accommodate a variety of plastic bottles having pedaloid bases without 
requiring tailored mechanical structures especially made for different 
plastic bottles. 
Still another object of the present invention is the provision of a device 
and method, as defined above, which device and method includes a single 
arcuate rib fixed with respect to the fixed guide plate of a capping 
machine, which rib engages a mechanical feature of a bottle to prevent 
rotation of the plastic bottle during the standard capping operation 
without reliance on friction forces and/or downward capping forces exerted 
by the capping operation. 
These and other objects and advantages will become from the following 
description taken together with the accompanying drawings which are 
hereafter described.

PREFERRED EMBODIMENT 
Referring now to the drawings wherein the showings are for the purpose of 
illustrating a preferred embodiment of the invention only and not for the 
purpose of limiting same, FIGS. 1 and 2 illustrate a somewhat standard 
capping machine A of the type used in capping a plastic PET bottle B 
having various sizes and lengths. In accordance with the illustrated 
embodiment, bottle or container B includes a generally cylindrical body 10 
having an upper threaded neck 12 connected to the body by diverging top 
portion 14 and provided with a circular flange 16. The base of container 
or bottle B is a pedaloid base 20 which is quite common in the plastic 
container industry for use with soft drinks and bottled beverages. A 
pedaloid base is a base with a number of distinct downwardly extending 
pads with flat surfaces divided by generally diverging recesses. In the 
illustrated embodiment pedaloid base 20 includes five pads 20a-20e 
separated by five diverging recesses 22a-22e best shown in FIGS. 6 and 7. 
Each pad has a generally lower flat support surface. This type of bottom 
structure gives rigidity and stability to a relatively thin bottle B 
formed by a standard plastic blow molding process. Onto the upper neck 12 
machine A applies a plastic threaded cap C in accordance with standard 
procedure. 
Capping machine A includes a central turret 40 rotatable about machine axis 
x and supported on lower base 42. In the illustration, turret 40 includes 
a shoulder 44 and a centering extension 46 for receiving standard star 
wheel 50 supported by a two piece ring 52 bolted by bolts 54 around 
extension 46 and fixed onto shoulder 44. The star wheel includes a 
plurality of outwardly projecting arms 56 supported by posts 60 onto ring 
52. A plurality of downwardly projecting pegs 64 extend below poste 60. 
These downwardly extending pegs 64 at each arm 56 have a plurality of 
axially spaced adjustable grooves 66, which are adapted to receive a 
bottle stabilizer ring 70 by way of a mounting housings 72 that are 
movable axially along posts 64 by retracted spring bias pin 74 in 
accordance with standard practice. The outward most end of stabilizer ring 
70 includes arcuate recesses 76 adapted to engage and stabilize the body 
10 of bottle B. In practice, when using the present invention it may be 
possible to dispense with the use of stabilizer ring 70. A stabilizer 
structure can be individual members supported on posts 64; however, in the 
illustrated embodiment the stabilizer ring 70 having a plurality of 
circumferentially spaced arcuate recesses 76, best shown in FIG. 2. Arms 
56 each include an arcuate nesting pocket 80 with an arcuate outer edge 
and adapted to receive an upper anti-spin insert 82 also having an arcuate 
edge or end 84. In practice, the upper surface of insert 82 has a 
plurality of arcuately spaced knife ridges 82a referred to as knife stars 
to engage the lower portion of flange 16 on bottle B. These knife ridges 
or knife stars are not necessary; however, they may be used with the 
present invention and are shown in FIG. 2. The upper surface of insert 52 
can be otherwise modified or roughened to prevent rotation by frictional 
engagement with the under surface of flange 16; however, this feature is 
generally not used with the present invention, since spinning on such 
modifications will cause scuffing of the plastic forming the under surface 
of flange 16. 
Capping machine A also includes a plurality of capping heads 100 rotated 
about machine axis x in unison with star wheel 50 by turret 40. Each 
capping head is located above a pocket 80 of star wheel 50 and includes a 
collet 102 driven by a standard clutch 104 through a drive unit 106, as 
shown in FIG. 2. As bottles B move in an arcuate path shown in FIG. 1, the 
capping head with a cap C in collet 102 is movable downwardly along 
capping axis y concentric with a bottle or container B held in pocket 80. 
The cap is then rotated until clutch 104 experiences a proper amount of 
torque. At that instance, collet 102 is moved upwardly leaving capped 
bottle B for further movement through machine A. In accordance with 
standard practice, a fixed guide plate 120 is positioned diametrically 
opposite pockets 80 of star wheel 50 and includes an arcuately shaped 
guide surface or edge 122 having a center of curvature corresponding 
generally with machine axis x. Plate 120 is spaced outwardly from star 
wheel 50 a distance necessary to allow guide surface or edge 122 to hold 
bottles B in pockets 80 as they are moved in a circular path by rotation 
of star wheel 50 by turret 40 and in unison with the matching capping 
heads 100. To fixedly locate surface or edge 122 of plate 120 in the 
proper position with respect to the rotating bottles B, support shafts 130 
are provided with upwardly extending threaded portions 132. Lock bolts 
134, 136 clamp fixed guide plate or back plate 120 with respect to the 
rotating bottles B in accordance with standard practice. Stabilization of 
upstanding shafts 130 is provided by a fixed support bar 140 having a more 
arcuate recess 142 and positioned on the top post 150 supported on base 
160 of machine A. Bar 140 has an angular length matching plate 120 and 
allows shafts 130 to be threaded onto the top of posts 150 spaced radially 
around machine A in the positions illustrated in FIG. 2. As shown in this 
Figure, an entrant guide mechanism 170 directs filled bottles B to the 
capping machine A at an entrant point. In a like manner, exit guide 
mechanism 172 removes capped bottles B from machine A at an exit point so 
the bottle move to the exit portion of the bottling line. 
In operation, filled bottles B are moved in an assembly line fashion 
through entrant guide mechanism 70 to capping machine A. The bottles are 
then engaged by nesting pocket 80 of star wheel 56 and are held in this 
position by fixed guide plate 120. As turret 40 rotates in the direction 
indicated by the arrow in FIG. 1 and the arrow in FIG. 2, bottles B move 
in an arcuate path after the bottle has been captured by machine A. A 
capping head moving in unison with a pocket 80 and having a cap C in 
collet 102 starts the capping process by rotating cap C over threaded neck 
12 above circular flange 16 of bottle B. As the bottle is restrained from 
rotational, it is moved by turret 40 around machine A. The capping head 
finalizes the capping operation and is withdrawn from bottle B before the 
bottle reaches exit guide mechanism 172. Inserts 82 with recesses 84 
actually engage the bottle at the lower surface of flange 16. In the past, 
the upper surface of these inserts were provided with the knife ridges 
schematically illustrated as ridges 82a in one of the inserts 82 in FIG. 
2. This is for illustrative purposes only since these knife ridges 82a are 
not required in practicing the invention, but they may be a part of the 
standard machine and need not be removed before adopting the machine with 
the present invention. 
In accordance with the invention, capping machine A is provided with an 
anti-rotation plate 200 in the form of an arcuate metal plate having 
radially inward edge 202 and radially outward edge 204. As shown in FIG. 
3, plate 200 includes outwardly protruding tabs or ears 206 and 208 for 
fixedly supporting plate 200 below guide plate 120 and directly below axes 
y of several capping heads 100 to engage the bottom of bottles B as the 
bottles are capped and moved along the arcuate path determined by rotation 
of turret 40. Tabs or ears 206 include holes 206a and 206b for bolts 230. 
Holes 208a and 208b in tab 208 are adjustable to accommodate assembly of 
anti-rotation plate 200 in the proper position on posts 150. Plate 200 
includes an entrant end or tongue 210 having a length determined by angle 
Z, tongue 210 is, in practice, bent slightly downwardly to accommodate 
bottles riding onto the top of a plate 200 as the bottles are moved from 
entrant guide mechanism 170 onto capping machine A. To fixedly mount plate 
200 in its proper position to engage bases 20 of bottles B, the preferred 
embodiment includes a plurality of clamps 220 having a slot 222 
intersecting bore 222a dimensioned to slide over one of the posts 150. 
Threaded head 224 is rotated by lever 226 to collapse slot 222, thus 
locking clamp 220 onto post 150 at the desired vertical position below 
fixed guide plate 120. Bolts 230 assemble clamps 220 onto the lower 
surface of plate 200 as shown in FIGS. 1 and 2. 
In accordance with the invention, fixed arcuate plate 200 includes an 
upwardly extending rib R having a center of curvature cc, which is 
generally concentric with machine axis x, as shown in FIG. 3. Rib R 
extends upwardly from a flat upper surface 240 of plate 220. As shown in 
FIGS. 4 and 5, rib R has a generally flat top 250 and curved edges 252, 
254. The height of the arcuate rib R in practice is 1/8 inch and the 
thickness of plate 200 is 1/4 inch. The width of rib R is 0.312 inches and 
the radius of each curved edge of the rib is 0.093 inches. These 
dimensions are representative and are used in practice for standard 
bottles having five pads in the lower pedaloid base. The height of rib R 
should be less than about 0.150 inches if a plate surface is used. 
However, the invention can be practiced with only a rib and without any 
supporting surface 240 of plate 200. In this manner, only the rib would 
engage the bottoms of bottles B. In the illustrated embodiment, the pads 
are generally spaced above surface 240 as shown in FIG. 6. The invention 
is essentially the use of a arcuate rib, or a rib matching the path of the 
moving bottles through a capping machine, which rib extends upwardly into 
the recesses of a pedaloid base used in a plastic bottle being capped. The 
action of the rib with respect to base 20 of bottle B is illustrated in 
FIGS. 6 and 7. As illustrated in FIG. 8, bottle B' has a four pad pedaloid 
base with pads 300-306. The same rib R can engage the bottom surface of 
the bottle B' with four pads and bottle B with five pads. An advantage of 
the present invention is that the rib R can be used with various types of 
pedaloid bases and various bottles having recessed configurations 
engagable by the upstanding arcuate rib R. The same rib structure can be 
used for various bottles. In addition, the rib is stationary and the 
bottles move or slide along the rib. Consequently, there is no need to 
synchronize the position and movement of the rib with respect to the 
rotating action of capping machine A. 
FIG. 5 illustrates the preferred embodiment for forming rib R in plate 200. 
An end mill removes material from the top of plate 200 to a depth, in 
practice about 1/8 inches, for defining the upper surface 240 of plate 
200. This is done by an end mill which has a radius end matching edges 
252, 254. By using a numerical controlled end mill, the arcuate 
configuration of rib R as shown in FIG. 3 can be easily produced. To blend 
rib R into the entrant guide mechanism 170 for incoming bottles, a portion 
of rib R can be contoured, as shown in FIG. 3 at entrant end or tongue 210 
of plate 200. Rib R' can be an elongated metal strip 310 mounted in a 
milled slot 312, as shown in FIG. 9. This is not the preferred embodiment 
for providing a rib on the top of surface 240 of plate 200. FIG. 9 merely 
illustrates the possibility of other arrangements for mechanically 
providing a rib to be used in accordance with the present invention.