Easily Changeable Gripping Head for Blow-Molding Pallet Assembly

FIG. 1 is a simplified, partially cutaway drawing of prior art apparatus employed for releasably holding and rotating a preform for heating thereof.

FIG. 2 is a simplified, partially cutaway drawing of applicant's basic gripping apparatus.

FIG. 3 is a partially cutaway side view of gripping and rotating apparatus according to the present invention.

FIG. 4 is a top view of the inner collet of the present invention.

FIG. 5 is a top view of the combined heat shield and locking plate of the present invention.

FIG. 6 is a top view showing the manner in which the inner collet is releasably locked in place by the locking plate.

FIG. 7 is a simplified drawing of the detent employed in the present invention.

A single station on a pallet 28 according to the present invention is shown in side view in FIG. 3 wherein it is generally indicated as 38. Each station 38 comprises a circular drive spindle disk 40 having a centrally located drive spindle shaft 42 with an axial bore 44 therethrough. A combined heat shield/locing plate 46 is disposed over the drive spindle disk 40. Heat shield/locking plate 46 comprises a cylindrical heat shield 48 closed at the top end by a circular locking plate 50 having a central bore 52 therethrough through which the drive spindle shaft 42 is disposed, whereby the heat shield/locking plate 42 can be rotated about the drive spindle shaft 42. With the heat shield/locking plate 46 disposed over the drive spindle disk 40, the drive spindle shaft 42 is disposed through a bore 54 in the pallet 28 and a drive sprocket 56 is mounted thereon, whereby the drive spindle disk 40 and heat shield/locking plate 46 can be rotated in combination by rotation of the drive sprocket 56. A circular pusher disk 58 is mounted on the bottom end of a knockout rod 60 slidably disposed within the axial bore 44 of the drive spindle shaft 42. A coil spring 62 is disposed over the knockout rod 60 against the top of the drive sprocket 56 and held in place by a circular retainer 64 mounted on the upper end of the knockout rod 60. Spring 62 biases the pusher disk 58 to a raised position against the inner surface of the drive spindle disk 40. By a pressure against the retainer 64 compressing the spring 62, the pusher disk 58 can be pushed downward against a preform to release it when desired.

Ease of adaptability is provided by an inner collet 66 constructed in the manner of applicants' invention of FIG. 2. By changing the inner collet 66, the stations 38 can be quickly and efficiently reconfigured to a new size preform. The inner collet 66 comprises a cylindrical gripping portion 68 having the spring metal fingers 30 of applicants' invention of FIG. 2 disposed peripherally around the bottom inner surface thereof for releasably gripping the neck 32 of a preform 14 in the manner previously described in detail in applicants' above-referenced applications. The cylindrical griping portion 68 has an internal diameter sized to fit about the pusher disk 58 and has a top planar surface 70 adapted to fit against the inner surface of the drive spindle disk 40. As best seen with reference to FIG. 4, there are a pair of opposed collet pins 72 extending upward from the surface 70 and a pair of opposed ball detent members 74 offset from the collet pins 72 also extending upward from the surface 70. The collet pins 72 each have a flattened head 76 of enlarged diameter thereon. The drive spindle disk 40 has a pair of opposed bores 78 therethrough through which the heads 76 of the collet pins 72 can pass. The drive spindle disk 40 also has a pair of opposed bores 80 therethrough through which the ball detent members 74 can slidably pass when the inner collet 66 is concentrically aligned with the drive spindle disk 40. As best seen in the top view of FIG. 5, the locking plate 50 has a pair of opposed bulbous slots 82 therethrough which can be rotated into alignment with the bores 78. The bulbous slots 82 have enlarged ends 84 sufficiently large enough for the heads 76 to pass therethrough communicating with slot ends 86 sized to fit around the collet pins 72 but insufficiently large enough for the heads 76 to pass therethrough. The locking plate 50 also has a pair of opposed bores 88 positioned to align with the detent members 74 when the collet pins 72 are within the slot ends 86 of the bulbous slots 82.

Each of the ball detent members 74 is constructed in the manner shown in FIG. 7 and comprises a cylindrical body 90 having a captive ball 92 and extending outward from the top thereof under bias force of a spring 94. To assemble the inner collet 66 to the drive spindle disk 40, the heat shield/locking plate 46 is rotated to place the enlarged ends 84 of the bulbous slots 82 in alignment with the bores 78. The collet pins 72 and ball detent members 74 are then inserted into the bores 78, 80, respectively, and the top planar surface 70 pushed tightly against the inner surface of the drive spindle disk 40. The ball 92 of each ball detent member 74 is compressed against the inside of the locking plate 50 and the heads 76 on the collet pins 72 pass beyond the top of the locking plate 50. The components then appear as shown in FIG. 6. With the inner collet 66 gripped for non-rotation, the heat shield 48 is gripped and rotated in the direction of the arrow 96. This causes the heads 76 to move over the slot ends 86 and for the balls 96 to snap into the bores 88 to prevent the locking plate 50 from reversing direction inadvertently to release the inner collet 66. To replace the inner collets 66 with others sized to grip another size preform for reconfiguration of the machinery, the above-described procedure is simply reversed. Thus, reconfiguration can be affected quickly and accurately in a matter of minutes instead of hours and days.