Structure and Working Principle of Huahong Press Lifting Units

In CNC grinding machines, precision Presses, hydraulic forming equipment, and automated press-working lines, the lifting unit is a core auxiliary mechanism that ensures proper mold opening and closing, workpiece demolding, stroke resetting, and precise pressure adjustment. Many equipment malfunctions—such as sticking during the return stroke, difficulty in demolding, stroke deviations, and delayed pressure resetting—often stem from a lack of familiarity with the lifting unit's structure and principles, inadequate maintenance, or improper parameter adjustment. Huahong provides a detailed overview of the structure and working principle of its press lifting units, as follows: I. Complete Structure of the Press Lifting Unit Huahong series press lifting units feature a modular, integrated design characterized by compactness, high rigidity, and rapid response. The system comprises four main modules: mechanical structure, hydraulic power unit, electrical control and sensing system, and safety protection. The core components are as follows: 1. Mechanical Actuator (Core Load-Bearing Components) Includes lifting tie rods, connecting brackets, fixed lifting lugs, guide columns, limit stops, and buffer pads. The mechanical structure is fabricated from high-strength cast steel and welded heavy-gauge steel plate, ensuring high rigidity, fatigue resistance, and resistance to deformation. Its primary function is to connect the press slide to the power assembly, ensuring vertical guidance without deviation or oscillation during the lifting process, preventing sticking caused by off-center loads, and maintaining linear accuracy during the press head's return stroke. 2. Hydraulic Lifting Power Assembly Composed of a lifting cylinder, piston, seal kit, check valve, pressure relief valve, and hydraulic fittings. Serving as the system's power source, it utilizes hydraulic pressure to actuate piston extension and retraction, enabling smooth lifting and lowering. Huahong’s genuine lifting cylinders feature precision-honed bores and wear-resistant seals, ensuring excellent sealing performance, zero leakage, and stable pressure, making them suitable for long-term, high-frequency start-stop operations. 3. Hydraulic Control Circuit System Includes solenoid directional control valves, throttle valves (flow control), pressure regulating valves, hydraulic filters, and pressure-stabilizing circuits. Solenoid valves switch the hydraulic flow direction to control the extension and retraction of the lifting cylinders, while throttle valves precisely regulate lifting and lowering speeds; this allows for controlled speed transitions, preventing sudden shocks that could cause equipment vibration or mold damage. 4. Electrical Detection and Control System Composed of limit switches, position sensors, and CNC signal reception modules. It monitors the slide's lifting height and reset position in real-time, feeding signals back to the CNC system to enable automatic stopping upon reaching position, automatic locking, and coordinated downward pressing. This ensures precise sequencing of automated processes and eliminates defects or equipment collisions caused by incomplete travel. 5. Safety Protection Structure Includes mechanical limit blocks, overload pressure-relief protection, explosion-proof hydraulic circuitry, and dust-proof guards. These features effectively prevent anomalies such as over-travel, over-pressure, and sudden pressure loss, protecting the machine body, molds, and operators while significantly enhancing operational stability. II. Standard Operating Principle of the Press Lifting Device The Huahong press lifting device employs an integrated operational logic combining hydraulic drive, mechanical guidance, and electrical coordination. The process comprises three stages: downward pressing and holding, return lifting, and reset/locking, ensuring clear operational logic and smooth movement: 1. Downward Pressing and Forming Stage The equipment initiates the pressurization cycle; the hydraulic system switches the flow path, placing the lifting cylinders in a pressure-released, slack state. The press slide descends at a constant speed driven by the main cylinder's pressure, engaging the mold to complete pressing, grinding, or forming operations. During this phase, the lifting mechanism remains in a passive standby mode, ensuring it does not interfere with the main ram's pressing accuracy or compromise forming pressure stability. 2. Return Lifting Stage (Core Operational Phase) Upon completion of the pressing/grinding process, the system receives a return signal. The solenoid directional valve switches, directing pressurized oil into the rodless chamber of the lifting cylinders to push the piston upward. A tie-rod structure evenly pulls the press slide upward smoothly, counteracting mold adhesion and overcoming the resistance of the slide's own weight; this resolves issues such as mold sticking, stuttering during the return stroke, and insufficient lifting force. Simultaneously, throttle valves regulate speed to ensure a gentle, shock-free lifting motion, thereby protecting the mold and the machine's structural integrity. 3. Return, Reset, and Locking Phase When the slide rises to the designated stroke position and triggers the stroke sensor, the system automatically cuts off the oil supply; the cylinder maintains pressure and locks, and the slide stops precisely at the preset home position, completing a full cycle. The equipment can immediately proceed to the next blanking and pressing operations, enabling continuous, automated cyclic production. Although the Press Lifting Mechanism may appear to be merely an auxiliary structure, it is actually a critical component that determines the equipment's level of automation, processing stability, and the precision of the finished product. A thorough understanding of its composition and operating principles, combined with proper operation and routine maintenance, can effectively prevent common issues such as insufficient return force, difficulty in demolding, stroke deviations, and abnormal equipment noises or jamming.