Automatic mandrel checker

Apparatus for sensing contaminant material or hung-up work pieces on mandrels, such as the core rods of injection blow molding machines, consists of a sensing member adapted to be moved through a programmed path corresponding to the bottom contour edge of the mandrel and to give an output responsive signal when any material or work piece remains on the mandrel and interrupts the programmed movement of the sensing member. Generally, one or more horizontally extending mandrels are checked by a sensing member linked through a connecting member with a cam following a cam track corresponding in shape and located below the bottom contour edge of the mandrel to be checked. In the preferred form of the invention, an injection blow molding machine includes an automatic stripper and checker, in which stripping fingers associated with the connecting member precede the sensing member and thus strip a preformed work piece off the mandrel simultaneously with the checker sensing member movement along the mandrel length. Preferably, the sensing member consists of a horizontally disposed rod adapted to travel along either one or a plurality of parallel core rods with the sensing member forming part of an electrical circuit. Upon engagement of the sensing member with hung-up material or work piece, the sensing member is adapted to yield downwardly and thereby to open the circuit and provide a responsive output signal.

This invention pertains to an automatic mandrel checker adapted to indicate 
the presence of foreign material on a generally horizontally extending 
mandrel. More particularly, this invention pertains to an injection blow 
molding machine with an automatic core rod stripper and checker. 
Manufacturing apparatus often includes mandrels about which are formed 
various types of hollow work pieces. In the cyclic operation of such 
apparatus, it is often necessary regularly to check the mandrels, after a 
work piece has been formed thereon and removed and before the mandrel is 
reused for a subsequent operation, in order to ensure that a previously 
formed work piece, or part thereof or some material involved in the 
preceding manufacturing step, has not remained on the mandrel. Feeler 
gauges adapted to sense such foreign matter are often used automatically 
to check mandrels for this purpose. 
In an injection blow molding machine, a plastic parison is first injection 
molded about a core rod (or mandrel). Subsequently, the parison is blown, 
such as by pressurized air introduced within the parison from the outer 
walls of the core rod, into a finished work piece configuration, such as a 
plastic bottle. If a previously formed product sticks to or for some 
reason otherwise remains on the core rod of if some portion of an unblown 
parison remains on the core rod, serious damage can result when the 
machine proceeds to position the core rod for subsequent formation of 
another parison thereon. 
Thus, in applications such as injection blow molding machines, there is a 
need for a reliable and sensitive checker for automatically and regularly 
sensing for the presence of foreign material on a core rod during a 
specific stage of the manufacturing operation. 
The general object of the present invention is to provide just such an 
automatic checker and more specifically to provide in an injection blow 
molding machine an automatic checker and stripping mechanism wherein 
previously formed work pieces are simultaneously stripped and the mandrel 
upon which they have been formed checked prior to reuse of the mandrel or 
core rod. 
This object and other more specific objects such as will be apparent in the 
course of the subsequent description of this invention are met, briefly, 
by an automatic mandrel or core rod checker in which a sensing member is 
adapted to be moved along a path corresponding to the bottom contour edge 
of a generally horizontally extending mandrel or core rod and to give a 
responsive output signal if any foreign object or material remains thereon 
and thus interrupts the predetermined path of movement of the sensing 
member. Preferably, the sensing member is associated through a connecting 
member with a cam follower and cam track, which corresponds in shape and 
is disposed below and parallel to the bottom contour edge of the mandrel 
or core rod to be checked. Still more preferably, a plurality of parallel 
extending mandrels or core rods are checked simultaneously by a sensing 
member consisting of a horizontally extending rod suspended between 
connecting members and associated with a cam and cam track as described 
above. In this embodiment of the invention, the sensing member rod is 
adapted to yield downwardly in response to the presence of a foreign 
material on any one of the mandrels or core rods and thereby to open a 
circuit of which the rod is part. 
Also, in the most preferred form of the present invention the connecting 
member is driven horizontally and attached to a connecting member element 
through a pivoted parallelogram arrangement. This connecting member 
element, upon which is mounted the cam and sensing member, is thus 
retained in its vertical orientation. The connecting member also has 
asssociated with it, stripping fingers adapted to precede the sensing 
member in the course of its movement along the mandrel or core rod and 
thereby to strip previously formed work pieces therefrom. Such an 
automatic stripper-checker mechanism is ideally suitable for use in an 
injection blow molding machine.

Turning more specifically to FIGS. 1-3, there is shown a plurality of 
injection blow molding machine mandrels or core rods 10 engaged by 
stripping finger member 12. For directional delivery of work pieces at the 
outer limit of its horizontal stroke, stripping finger member 12 is 
connected to shaft 14, which is in turn adapted to be periodically rotated 
through a partial arc by rotaing cylinder 16. Horizontal movement is in 
turn imparted to shaft 14 and stripping finger member 12 by the mounting 
of shaft 14 in connection member 18. 
The rotational movement of stripping finger member 12 at the outer end of 
its horizontal stroke is illustrated in phantom FIG. 3. 
As seen in FIG. 2A, the horizontal actuation movement of the stripping 
mechanism and particularly the connecting member 18 is effected by 
cylinder 20 and piston rod 22 projecting therefrom, attached through tie 
bar 61 to guide rods 60, which slide through bushing block 35 associated 
with mounting plate 33 and are attached to connecting member 18. Stop 
member 19 is provided to limit the reverse horizontal movement of 
connecting member 18 and apparatus associated therewith at the conclusion 
of the actuation and return stroke. 
Attached through pivotally attached parallelogram links 24 to connecting 
member 18, is separate, generally vertically disposed, connecting member 
element 26 associated at its lower end with a cam follower 28. Cam 
follower 28 is in turn engaged by and adapted to traverse generally 
horizontally along cam track 30, which corresponds in shape and is 
disposed parallel to and below the lower contour edge 32 of core rods 10. 
At the upper ends of connecting member elements 26, they are secured to a 
horizontally extending support bar 34, to which in turn is secured 
vertically projecting sensing member supports 36. Supports 36 are secured 
to and vertically adjustable within bar 34, the vertically adjusted 
position thereof being retained by set screws 39 and lock nut 40. 
At the top of supports 36 is disposed a second support bar 38, in turn 
supporting, at its ends, upwardly extending pins 41 with an upper head 
stop 42. 
As seen better in the detailed view of FIG. 4, upwardly extending pin 41 is 
insulated along its axial length, by an insulator 44, from sensor rod end 
46, which otherwise is urged upwardly by coil spring 48. 
Also, as better seen in FIG. 4, upwardly extending pin 41 is secured in a 
non-conductive end extension 38A of second support bar 38. 
As illustrated in FIGS. 3 and 4, when sensor rod 50, which is urged 
upwardly into engagement with stophead 42, is forced downwardly against 
that urging by a work piece or foreign material on the outer surface of 
core rod 10, electrical contact is broken between stophead 42 and sensing 
member end 46. Accordingly, the presence of such foreign material is 
sensed by the provision, in the preferred embodiment of the present 
invention, of an electrical circuit formed between the two upwardly 
extending pins 41 at the opposite ends of sensor member 50. In the event 
that either or both ends of sensor member 50 are forced downwardly and 
away from engagement with upper stophead 42, the circuit is broken and an 
output signal is provided, which may be utilized to stop the machine or 
give an output visual or audio warning. 
In operation of the apparatus shown in FIGS. 1-4, when a set of core rods 
is positioned at the stripping-checking station of an injection blow 
molding machine, in which the automatic stripper-checker of the present 
invention is incorporated, the piston in cylinder 20 is actuated and 
piston rod 22, connecting member 18 and connecting member element 26 are 
moved outwardly in a generally horizontal direction. Thus horizontally 
actuated, stripper finger member 12, moves work pieces formed on core rods 
10 outwardly as cam follower 28 traces the path of the bottom edge contour 
of core rod 10 by following cam track 30, corresponding in shape thereto, 
thereby normally causing sensing member 50 to follow an identical path. If 
foreign material, such as unblown parison material or a work piece part is 
stuck on one of the core rods 10, sensing member 50, which is urged 
upwardly by coil spring 48, yields downwardly and causes a discontinuity 
in the electrical circuit otherwise established between upwardly extending 
pins 41 at the opposite ends of the machine, causing an output responsive 
signal which may be used to stop the machine or produce a visual or audio 
alarm. 
At the outer limit of the horizontal stroke of finger member 12, rotating 
cylinder 16 rotates stripper finger member 12 downwardly, as shown in 
phantom in FIG. 3, causing work pieces engaged therein to be deposited 
just downward and outward of the outer limit of stripper finger member 12, 
at its lowered position. 
Stripper finger member 12, sensor member 50 and their associated carrier 
equipment, including connecting member 18, are then returned to their 
starting position and core rods 10 are moved to their next work position. 
While this invention has been described and illustrated with respect to a 
specific embodiment, it is not limited thereto and the appended claims are 
intended to be construed to encompass other variations and modifications 
of the invention which may be made by those skilled in the art without 
departing from the true spirit and scope thereof. For example, while 
vertical and horizontal orientations are referred to, the invention may 
also be incorporated in an apparatus of different orientation so long as 
the elements of the invention function together in the same manner as in 
the embodiment illustrated and described.