Ejection Star Wheel for Preform Sorting in Blow-Molding
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Solution Overview
Problem
Existing blow molding machines face inefficiencies in preform sorting at high speeds due to conventional ejection mechanisms that unintentionally eject suitable preforms, causing delays and reducing process performance.
Innovation Solution
A sorting device with a transport wheel and a rotatably mounted ejection star wheel, featuring multiple ejection arms that securely hold and selectively eject preforms without the need for alternating movements, ensuring only unsuitable preforms are removed from the transport stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ejection mechanism with a pivoting guide collar is used to sort out defective preforms, then defective preforms can be removed from the transport stream, but suitable preforms are unintentionally ejected and transport is interrupted during the alternating pivoting movement
Solution Approach 1:
The ejection mechanism is segmented into multiple independent ejection elements (ejection fingers or needles) arranged around the transport wheel, each capable of independent actuation. This allows selective ejection of individual defective preforms without affecting the transport of other preforms, eliminating the need for alternating pivoting movements and maintaining continuous high-speed transport.
Solution Approach 2:
The ejection mechanism transitions from a static pivoting guide collar to dynamic, individually controllable ejection elements that can be activated only when and where needed. This dynamic approach allows the system to maintain continuous transport while selectively removing defective preforms, resolving the contradiction between sorting accuracy and transport productivity.
2Reliability
If the guide collar is pivoted out to eject preforms, then defective preforms are removed, but the pivoting movement causes time delays and stops further preform transport
Solution Approach 1:
Defective preforms are identified and marked for ejection before reaching the ejection zone through optical inspection systems. This preliminary detection allows the control system to prepare for selective ejection, ensuring that only defective preforms are removed without interrupting the continuous transport flow, thus eliminating time delays associated with alternating pivoting movements.
Solution Approach 2:
The ejection mechanism is designed to operate continuously alongside the transport wheel, with ejection elements positioned to remove defective preforms without stopping or interrupting the transport cycle. This continuous operation eliminates the time losses inherent in alternating pivoting movements while maintaining quality control through selective ejection.
3Reliability
If multiple preforms are ejected simultaneously by the guide collar mechanism, then sorting is performed, but the alternating movement pattern reduces overall process speed
Solution Approach 1:
The ejection function is segmented into multiple independent ejection elements distributed around the transport wheel circumference. Each element can independently eject a single defective preform as it passes by, allowing continuous selective ejection without alternating movements. This segmentation maintains sorting accuracy while enabling high-speed continuous transport.
Solution Approach 2:
The ejection elements are activated periodically as defective preforms pass their respective positions, rather than using alternating pivoting movements. This periodic activation pattern allows multiple preforms to be ejected at different times during continuous transport, maintaining both sorting accuracy and high transport speed.
Data Source
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AI summary
The invention relates to devices and to methods for transporting preforms in the region of a blow-molding machine, in particular a sorting device (10) for transporting preforms (20) composed of a thermoplastic material in the region of a blow-molding machine for the blow-molding of containers, comprising a transport wheel (12), which has a plurality of accommodating recesses (18) for accommodating and conveying the preforms (20), which accommodating recesses are arranged on the circumference of the transport wheel in such a way that the accommodating recesses are distributed in the circumferential direction, a guide collar (16), which extends circumferentially around the transport wheel (12) in some regions in such a way that the guide collar is radially spaced apart from the transport wheel, wherein the preforms (20) are transported hanging between the transport wheel (12) and the guide collar (16) in the region of the sorting device (10), and a selecting unit for selectively removing an individual perform (20) transported in one of the accommodating recesses (18) of the transport wheel (12) in each case, wherein the selecting unit comprises a rotatably supported ejecting star (14) having a plurality of ejecting arms (31), which ejecting star, in the idle position, reaches into the circumferential region of the transport wheel (12) by means of a first ejecting arm (31) immediately adjacent to the guide collar (16) in the transport direction of the preforms (20), in such a way that the preforms (20) transported past the first ejecting arm (31) in the accommodating recesses (18) are secured against unintentionally falling out, wherein the ejecting star (14), in the event of a rotational motion, pushes an individual preform (20), which is to be removed, out of one of the accommodating recesses (18) of the transport wheel (12) by means of a second ejecting arm (32) following the first ejecting arm (31), and wherein, in a recurring manner after the preform (20) to be removed has been pushed out, the second ejecting arm (31) takes on the securing of the preforms (20) transported past the second ejecting arm against falling out of the accommodating recesses (18).