Hydraulic Pump Reverse Rotation for Injection Molding Depressurization

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Solution Overview

Problem

Conventional injection molding machines face issues with residual pressure affecting smooth switching between operational processes, leading to shock pressure and slow depressurization, which hinders accurate and stable measurement processes.

Innovation Solution

The method involves variably controlling the rotation speed of a driving motor in a hydraulic pump to forcibly lower pressures to a specified target, using reverse rotation to quickly achieve the unload pressure, thereby preventing shock pressure and enabling smooth switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the operational pressure of the back-pressure valve is lowered by the proportional pressure control valve relying on natural pressure decrease, then the injection-side oil chamber can be depressurized, but the time until the desired pressure is achieved becomes long due to fluidity and flow path resistance

Engineering Contradiction:

Improvedepressurization completenessVSAvoiddepressurization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The driving motor is made capable of reverse rotation to actively pump oil from the pressure pipeline back to the oil tank, inverting the normal unidirectional pumping function. This reverse operation creates an active depressurization mechanism that overcomes the limitations of passive pressure release, enabling rapid and complete circuit depressurization without being constrained by fluidity or flow path resistance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The driving motor serves as an intermediary device between the pressure pipeline and the oil tank during depressurization. By operating in reverse, it acts as an active mediator to transfer oil from the high-pressure circuit back to the tank, replacing the passive reliance on natural pressure decrease and enabling controlled, rapid depressurization of the entire hydraulic circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If residual pressure is not completely removed from the hydraulic pump side, then switching between operational processes can be performed, but shock pressure occurs during switching which prevents smooth operation and accurate measurement

Engineering Contradiction:

Improveprocess switching capabilityVSAvoidshock pressure

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The driving motor's reverse rotation capability enables active pumping of residual oil from the pressure pipeline back to the tank, completely removing residual pressure that would otherwise cause shock during process switching. This inverts the normal pumping direction to serve the specific purpose of complete circuit depressurization before switching to measurement or other processes.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The system performs preliminary depressurization of the entire hydraulic circuit, including the pump side, before switching between operational processes. By using the driving motor to actively pump out residual pressure in advance, the system ensures that no shock pressure occurs during subsequent process switching, enabling smooth transitions and accurate measurements.

Inventive Principle:

Principle #10Preliminary action

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 approach ensures quick and precise pressure control, preventing shock pressure during operational changes and allowing for stable operation control, even with fluidity or flow path resistance, by securely lowering residual pressures to a specified target.

Implementation Method 1

a hydraulic driving unit equipped with a hydraulic pump, based on which operational processes are controlled

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a specified hydraulic actuator is driven by a hydraulic driving unit equipped with a hydraulic pump

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Gradient

Implementation Method 3

when each pressure on the operational processes are lowered to a specified pressure, the pressure is forcibly lowered by reverse-rotating the driving motor

Methodology Applied

Scientific EffectReverse rotation pumping: Pump

Data Source

PatentUS7938994B2Method of controlling an injection molding machine

Publication Date: 2011.05.10 NISSEI PLASTIC IND CO LTD

AI summary

In a method of controlling an injection molding machine M which controls specified operational processes in a molding cycle by variably controlling the rotation speed of a driving motor 3 in a hydraulic pump 2 and driving a specified hydraulic actuators 4a, 4b, . . . , in lowering the pressure Pd of the operational process to a specified pressure Pn, the pressure Pd is forcibly lowered by controlling the driving motor 3 in reverse rotation.