Electric Cylinder Control System for Load Management
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Solution Overview
Problem
Existing methods for controlling electric cylinders driven by servomotors face challenges in maintaining a constant target load during pressurization, leading to overloading and prolonged pressurization times, especially when repeated in short cycles, due to inertia and stored pulses in the servo amplifier.
Innovation Solution
A method that involves setting a load for stopping below the target load and using command pulse signals to manage the number of stored pulses, allowing the servomotor to stop accurately without overloading, and adjusting the speed control to maintain the target load efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the speed of the rod is greatly decreased to about 1 mm/s just before the rod bumps against the material, then the load applied to the material can be controlled at the target load, but the time needed for pressurization becomes extremely long and productivity decreases
Solution Approach 1:
The patent applies dynamics by making the rod speed variable rather than constant. The control system dynamically adjusts the rod speed based on real-time feedback from the load detector. When the rod approaches the material and contact is detected, the speed is automatically reduced from the normal high speed (5 mm/s or more) to a low speed (about 1 mm/s) only for the brief period needed to control the pressing load, then restored after pressurization completes. This dynamic speed adjustment resolves the contradiction by maintaining high productivity during non-contact periods while ensuring precise load control during contact.
2Force
If the speed of the rod is decreased at a constant rate or proportional rate after the rod bumps against the material, then the target load can be reached, but the time from decreasing speed to reaching target load increases and productivity decreases
Solution Approach 1:
The patent employs feedback control where the load detector continuously monitors the pressing load and feeds this information back to the control system. Based on this real-time feedback, the control system adjusts the rod speed dynamically. When contact with the material is detected, the speed is immediately reduced to maintain precise control over the pressing load. This feedback mechanism eliminates the need for predetermined speed reduction rates, allowing the system to reach the target load efficiently while maintaining accurate load control, thus reducing the time loss compared to conventional constant rate deceleration methods.
3Measurement precision
If the servomotor is controlled in position-control mode using pulse signals, then the rod can be stopped at an accurate position, but the stored pulses in the servo amplifier cause the device to be overloaded and extend pressurization time
Solution Approach 1:
The patent applies self-service by having the control system automatically manage the pulse signal generation and stored pulse clearance based on load detector feedback. When the rod contacts the material and the load increases, the control system automatically generates reverse direction pulse signals to clear the stored pulses in the servo amplifier, preventing overload. This automatic self-management eliminates the need for external intervention to clear stored pulses, maintaining positioning accuracy while preventing the productivity loss that would occur from manual pulse clearance operations or system overloads.
Data Source
AI summary
The invention realizes a method for controlling an electric cylinder and a control system for the cylinder that can prevent a load for pressurizing from significantly exceeding a target load and can shorten the time for the pressurization. A servo controller 17 can set the speed of the rod 11 and a load for stopping Ps that is used for determining whether the rod 11 should be stopped so that the load for pressurizing Pm does not significantly exceed the target load Pt. The servo controller 17 drives the rod 11 under the position control mode and determines whether the load for pressurizing Pm that is detected by a load detector 13 is bigger than or equal to the load for stopping Ps. If it determines that the load for pressurizing Pm is bigger than or equal to the load for stopping Ps, the servo controller 17 provides a reverse command pulse signal to a servo amplifier 16 and causes stored pulses in the servo amplifier 16 to decrease, to thereby stop the rod at the load that does not significantly exceed a target load Pt.