Extrusion Press Hydraulic Circuit for Gradual Piston Acceleration
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Solution Overview
Problem
Existing metal extrusion presses face challenges with hydraulic circuits that require costly and complex variable displacement pumps and motors with low moment of inertia, which are expensive and difficult to manage, and result in inefficient energy use and frequent maintenance needs.
Innovation Solution
A press with a hydraulic circuit using a constant displacement pump driven by a variable speed electric motor, featuring a control unit with a pilot line and shutoff element that allows gradual pressure increase to control piston acceleration, reducing reliance on low moment of inertia motors and enabling controlled acceleration of pistons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a variable displacement pump is used to control piston speed, then the extrusion speed can be adjusted according to material type and die complexity, but the pump cost and complexity increase significantly requiring frequent maintenance
Solution Approach 1:
The patent applies dynamics by using a variable speed motor instead of a variable displacement pump. The motor speed can be dynamically adjusted through frequency control, which in turn controls the pump output and piston speed. This dynamic approach achieves speed control while maintaining simpler pump hardware that requires less maintenance.
2Reliability
If a constant speed motor drives a fixed displacement pump, then the system is simpler and more reliable, but energy efficiency decreases because the motor must run at constant speed even when not needed
Solution Approach 1:
The patent implements dynamics by enabling the motor speed to vary according to actual operational needs. The motor can be activated only when required and its speed can be adjusted via frequency control, optimizing energy consumption while maintaining system reliability through the use of a simple fixed displacement pump.
3Loss of time
If motors with low moment of inertia are used to rapidly vary rotation speed, then the response time of the hydraulic circuit improves, but the motor cost increases and additional cooling systems are required
Solution Approach 1:
The patent uses frequency control as an intermediary to adjust motor speed. This intermediary approach allows standard motors with higher moment of inertia to achieve the required response times without needing specialized low-inertia motors and their associated complex cooling systems.
4Reliability
If frequent maintenance interventions are performed on variable displacement pumps, then component failures can be contained, but production downtime and operational costs increase
Solution Approach 1:
The patent extracts the complexity and maintenance requirements from the hydraulic system by eliminating the variable displacement pump. The simplified fixed displacement pump system requires minimal maintenance, thereby reducing production downtime and maintaining operational continuity while still achieving the required speed control through motor frequency adjustment.
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 configuration allows for efficient energy use, reduced maintenance costs, and controlled acceleration of pistons, avoiding the limitations of traditional systems by using a more straightforward and cost-effective hydraulic circuit design.
Implementation Method 1
operated by an electric motor with a variable rotation speed
Implementation Method 2
a piston controlled by means of an oil hydraulic circuit which comprises
Data Source
AI summary
The invention relates to a press for extruding metal material. The press comprises a hydraulic oil circuit for controlling one or more extrusion pistons movable within corresponding cylinders. Such a circuit comprises a fixed displacement, circulation pump operated by an electric motor with variable rotation speed. The hydraulic circuit comprises a main line and a branch line, along which a shutoff element is arranged. The hydraulic circuit comprises a hydraulic control unit comprising a pilot valve arranged along a pilot line provided with a first segment communicating with the main line and a second discharging segment. Said hydraulic unit is provided to move the shutoff element between an opening position and a closing position of the branch line according to the difference between the oil pressure upstream of the shutoff element and that in the first segment of said pilot line. The hydraulic circuit further comprises a control element which, in an activation condition, and as a result of the activation of said pilot valve, determines a gradual increase of the pressure in the first segment of said pilot line and a corresponding gradual closing movement of said shutoff element causing a consequent gradual increase of the thrust on the piston until the reference speed is reached.