Hydraulic Power Unit Pressure Control for Molding Machines
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Solution Overview
Problem
Conventional match-plate molding machines face the challenge of maintaining oil pressure above the holding pressure of the accumulator, limiting the ability to reduce oil pressure supplied to hydraulic cylinder systems during sand squeezing.
Innovation Solution
Incorporation of a hydraulic power unit with electromagnetic directional control valves and pressure sensors that allow for precise control of oil supply to hydraulic cylinder systems, enabling the pressure to be reduced below the accumulator's holding pressure by stopping and reactivating oil flow based on measured pressure values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an accumulator is provided in the piping system to stabilize hydraulic circuit and buffer oil, then the hydraulic circuit is stabilized and oil is buffered, but the minimum oil pressure supplied to hydraulic cylinder systems cannot be below the holding pressure of the accumulator
Solution Approach 1:
A pressure control valve is introduced as an intermediary component between the accumulator and the hydraulic cylinder systems. This valve mediates the pressure transmission, allowing the system to utilize the accumulator's buffering capability while independently controlling the output pressure to be below the accumulator's holding pressure, thus resolving the contradiction between circuit stability and minimum pressure requirements
Solution Approach 2:
The invention changes the pressure parameter control approach by using a pressure control valve to dynamically adjust and reduce the pressure from the accumulator's holding pressure to a lower predetermined pressure level. This parameter transformation enables the system to maintain stability through the accumulator while delivering the required lower pressure to the hydraulic cylinder systems
2Stress or pressure
If electromagnetic directional control valves and pressure sensors are incorporated for precise control of oil supply, then pressure can be reduced below accumulator holding pressure, but device complexity increases
Solution Approach 1:
Pressure sensors are installed to detect the actual pressure in the piping system and provide feedback signals to the controller. The controller compares the detected pressure with the predetermined pressure value and automatically adjusts the electromagnetic directional control valves to maintain pressure below the accumulator's holding pressure. This feedback mechanism enables precise pressure control despite the added device complexity
Solution Approach 2:
The control system is designed to automatically regulate oil pressure without continuous manual intervention. The pressure sensors and controller work together to self-adjust the electromagnetic directional control valves based on real-time pressure conditions, enabling the system to maintain optimal pressure levels autonomously, which justifies the increased complexity through automation and reduced operational burden
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
Enables the minimum oil pressure supplied to hydraulic cylinder systems to be set below the holding pressure of the accumulator, improving the control and efficiency of the sand-squeezing process in match-plate molding machines.
Implementation Method 1
first and second electromagnetic directional control valves for controlling the flow of oil from the source to the first and second hydraulic cylinder systems
Implementation Method 2
first and second pressure sensors located in the piping system to associate with the first and second hydraulic cylinder systems for measuring the pressures of the oil within the piping system
Implementation Method 3
an accumulator that is provided within the piping system
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A hydraulic power unit 15 of a match-plate molding machine comprises a hydraulic pump 20 for supplying oil, a piping system 21, 25, and 26 that fluidly communicates with first and second hydraulic cylinder systems 7 and 10 for supplying the oil from the hydraulic pump 20 to them to perform a squeeze step, an accumulator 22 that is provided within the piping system, first and second electromagnetic directional control valves 23 and 24 for controlling the flow of the oil from the hydraulic pump 20 to the first and second hydraulic cylinder systems 7 and 10, first and second pressure sensors 27 and 28 for measuring pressures of the oil of the first and second hydraulic cylinder systems 7 and 10, and for generating output signals that correspond to the measured value, and a controller 29 for receiving the output signals from the first and second pressure sensors 23 and 24, and for controlling the turns of the first and second electromagnetic directional control valves 23 and 24 based on the output signals and the predetermined value within a range below the pressure holding the accumulator 22 against the oil.