Injection Molding Clamp Position Monitoring During Light Curtain Bypass
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Solution Overview
Problem
Existing systems for monitoring the position of the clamping unit in injection molding machines require significant hardware and adjustment efforts, making them time-consuming and prone to failure, especially during tool changes.
Innovation Solution
A system utilizing a programmable logic controller (PLC) with a motion monitoring unit (MOC) and two displacement measuring rods to indirectly monitor the position of the clamping unit, reducing hardware requirements and enabling reliable position monitoring even when the light grid is interrupted, with an MTTFd value of 1,536,098 hours for safety-relevant errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cam switches or light barriers are used for gap monitoring, then position monitoring is achieved, but hardware effort and adjustment time increase significantly
Solution Approach 1:
The patent replaces mechanical cam switches and optical light barriers with a laser-based measurement system. The laser measuring device emits laser beams that are reflected by the mold to determine gap position, eliminating the need for physical switches and complex optical alignment components.
Solution Approach 2:
The patent introduces a laser beam as an intermediary measurement medium. The laser light serves as a non-contact probe that interacts with the mold surface through reflection, enabling position detection without direct mechanical or optical component contact at the measurement point.
2Reliability
If cam switches or light barriers are used for gap monitoring, then position monitoring is achieved, but adjustment time increases significantly
Solution Approach 1:
The laser measuring system is designed to be self-aligning and automatically adapts to different mold positions. The system performs self-calibration by detecting the laser reflection from the mold surface, eliminating the need for manual adjustment by operators during tool changes.
Solution Approach 2:
The system performs preliminary measurement and calibration actions automatically upon initialization or tool change. The laser measuring device pre-establishes the measurement baseline and calibration parameters before production begins, so no time-consuming adjustment is needed during operations.
3Measurement precision
If multiple sensors are used for position monitoring, then measurement accuracy is improved, but system complexity and failure risk increase
Solution Approach 1:
The patent segments the measurement function into distinct operational phases: approach phase (coarse positioning) and measurement phase (precise gap detection). Each phase uses appropriate measurement methods, with the laser system focusing on precise gap measurement only when needed, rather than using multiple sensors simultaneously for all functions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces hardware effort and ensures reliable monitoring of the clamping unit position, allowing unrestricted bumping operations with reduced risk to the operator, as the mold only needs to open a few millimeters, and provides high accuracy through independent path measuring systems.
Implementation Method 1
displacement measuring rods being provided as sensors, the signals of which are processed via the MOC in the PLC
Implementation Method 2
a system for monitoring the position of the closing unit of an injection molding machine when bridging a light curtain serving to secure the closing unit and the mold area
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a system for monitoring the position of the closing unit of an injection molding machine (1) by bypassing a light curtain used to secure the closing unit and the tool area of the injection molding machine (1), wherein the injection molding machine (1) has at least one molding tool (4, 5, 6) comprising at least two parts, which encloses at least one mold cavity, wherein the injection molding machine (1) has a programmable logic controller (PLC) for controlling the movement monitoring module (MOC) for the indirect monitoring of the position of the closing unit and the position of the molding tool parts (4, 5, 6) in relation to one another, wherein distance measuring sticks (10, 12, 13) are provided as sensors, the signals of which are processed via the MOC in the PLC, wherein the molding tool part following the build-up of the closing pressure and the mold filling operation, in the following bumping step must maintain a spacing gap (16) in relation to each other, to which a specific maximum value is assigned, at which, if exceeded, the injection molding machine (1) switches off.