Bidirectional Pump Clamping System
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Solution Overview
Problem
Hydraulic clamping systems in machine tools are complex, costly, and prone to faults due to the use of solenoid-operated switching valves, which require additional structural effort and are susceptible to malfunctions, while also experiencing leakage issues that affect clamping pressure.
Innovation Solution
The system eliminates solenoid-operated switching valves by controlling the clamping cylinder direction through reversing the electric motor and pump rotation, utilizing a gear pump that delivers in both directions, and incorporating a rotary encoder for speed control and pressure sensors for precise pressure management, with 3/2-way valves compensating for volume differences and non-return valves to maintain a closed circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solenoid-operated switching valves are used to control the clamping cylinder direction, then the clamping system can achieve directional control, but the system complexity increases and operational reliability decreases
Solution Approach 1:
The patent removes solenoid-operated switching valves from the system entirely. Instead of using valves to control hydraulic flow direction, the system uses a bidirectional gear pump that can deliver hydraulic medium in both directions of rotation, eliminating the need for complex switching valve mechanisms and their associated solenoids.
Solution Approach 2:
The patent inverts the conventional approach by making the pump bidirectional rather than using unidirectional pumps with switching valves. The gear pump is designed to deliver hydraulic medium to different outlets based on rotation direction, reversing the traditional control methodology.
2Ease of operation
If solenoid-operated switching valves are installed for directional control, then clamping cylinder direction can be controlled, but additional structural effort and costs are required
Solution Approach 1:
The bidirectional gear pump serves multiple functions: it acts as both a pump and a directional control device. By reversing the pump's rotation direction, the system achieves directional control of the clamping cylinder without requiring separate switching valves, reducing structural complexity while maintaining operational capability.
3Reliability
If switching valves are used to control clamping cylinder direction, then directional control is achieved, but the system becomes susceptible to malfunctions
Solution Approach 1:
The patent extracts and removes the switching valves from the hydraulic system. By eliminating these potential failure points, the system reduces susceptibility to malfunctions while maintaining directional control capability through the bidirectional pump's rotation control.
4Productivity
If the clamping cylinder is controlled quickly from release to clamping position, then clamping cycle time is reduced, but clamping pressure must be maintained sensitively
Solution Approach 1:
The patent employs dynamic control of the bidirectional pump's rotation speed and direction. During the transition phase, the pump operates at higher speeds for quick positioning, then transitions to precise speed control near the clamping position to maintain sensitive pressure control, adapting its operation to different phases of the clamping cycle.
Solution Approach 2:
The system uses feedback from position sensors and pressure sensors to regulate the pump's operation. The controller adjusts the pump's rotation speed and direction based on real-time feedback, ensuring both rapid cycle times and precise pressure maintenance during the clamping process.
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 simplifies the control system, reduces costs, enhances operational reliability, and maintains clamping pressure by using a structurally simple and functionally reliable design that compensates for leaks, allowing for efficient and precise control of the clamping cylinder.
Implementation Method 1
The pump is a gear pump that delivers in both directions of rotation to one of two separate delivery outlets
Implementation Method 2
The direction of the clamping cylinder is controlled only by reversing the direction of rotation of the electric motor and the at least one pump
Implementation Method 3
The electric motor is a three-phase asynchronous motor or a synchronous motor, which is assigned a rotary encoder on the control side and a frequency converter for speed control. There is permanent feedback on the speed of the electric motor or the pump via the rotary encoder
Implementation Method 4
The electric motor is a three-phase asynchronous motor or a synchronous motor, which is assigned a rotary encoder on the control side and a frequency converter for speed control
Implementation Method 5
In order to increase operational safety, it is also expedient if pressure and/or position sensors of the clamping cylinder are used, which are preferably connected to a controller for the motor pump unit and/or clamping system
Implementation Method 6
3/2-way valves compensating for volume differences
Implementation Method 7
non-return valves to maintain a closed circuit
Implementation Method 8
Hydraulic clamping systems in machine tools
Data Source
Figure 1
Figure 2
AI summary
In a clamping system (S) of a machine tool (W), e.g. a lathe, with a double-acting clamping cylinder (1) which is directionally controlled by an electrically operated motor pump unit (5) connected to both actuation sides of the clamping cylinder, which contains at least one pump (8) driven by an electric motor (7) in a reservoir housing (6), the clamping cylinder (1) is directionally controlled without switching valves by reversing the direction of rotation of the reversible electric motor (7).