Preform Conveying Device with Sensor-Based Position Control
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Solution Overview
Problem
In two-stage or cold parison blow molding devices, the mechanical engagement between conveyor arms and jigs leads to wear of engaging members, necessitating frequent replacements and additional drive mechanisms for conveyor arm return, which complicates the conveying process.
Innovation Solution
A preform conveying device with a continuous conveyor section for jigs and an intermittent conveyor section for arms, controlled by a unit that calculates and adjusts the conveyor arm's target position based on the conveyor jig's position and delay times to catch up without mechanical engagement, using motors and encoders to synchronize movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical engagement members (rods and projections) are used to convey conveyor arms to face continuously moving conveyor jigs, then the conveyor arm can be positioned accurately, but wear of engaging members occurs and they must be replaced frequently
Solution Approach 1:
The patent replaces the mechanical engagement system (rods and projections) with a sensor-based detection and control system. Sensors detect the position of conveyor jigs, and a control unit calculates and commands the conveyor arm position accordingly, eliminating mechanical contact and wear while maintaining positioning accuracy.
Solution Approach 2:
The system uses the positional information from the continuously moving conveyor jigs (detected by sensors) to automatically determine when and where to position the conveyor arm, making the system self-regulating without requiring mechanical engagement members.
2Ease of operation
If additional drive mechanisms are added to convey conveyor arms back after transfer, then the conveyor arm can return to waiting position, but device complexity increases
Solution Approach 1:
The patent extracts the return conveyance function from the drive mechanism by utilizing the natural continuous movement of the conveyor jigs. The conveyor arm is passively returned to the waiting position along with the conveyor jig movement, eliminating the need for separate return drive mechanisms.
Solution Approach 2:
The continuous conveyor system serves multiple functions: it not only transports preforms but also automatically returns the conveyor arm to the waiting position, making the conveyor system multi-functional and reducing overall device complexity.
3Reliability
If mechanical engagement is used for conveyor arm movement, then the conveyor arm can be driven reliably, but maintenance frequency increases due to wear
Solution Approach 1:
The patent replaces mechanical drive and engagement mechanisms with a sensor-based detection and control system. The control unit commands the conveyor arm based on detected positions, eliminating mechanical wear and reducing maintenance frequency while maintaining reliable operation.
Data Source
AI summary
A preform conveying device (100) of the invention includes a control unit that detects an arriving time at which a conveyor jig arrives at a reference position based on an output of a first encoder, and commands a second motor to move a conveyor arm to a target position at regular intervals from the arriving time. The target position in each command is a position obtained by adding, to a current position of the conveyor jig which is obtained based on a latest output of the first encoder which was obtained when the command has been issued, a moving distance by which the conveyor jig has advanced during a delay time T which spans from a time when the latest output is outputted from the first encoder to a time when the command is received by the second motor.