Nested Piston Actuator for Welding Gun Force Control
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Solution Overview
Problem
Existing fluid actuators for resistance spot welding guns, particularly those with 'fulcrum' or 'slide' structures, face challenges in achieving precise and reliable control of electrode holder arms, leading to inconsistent weld quality due to limited force transfer and adjustment capabilities.
Innovation Solution
A fluid actuator design featuring a main piston unit with an auxiliary cylinder and a one-way valve system, along with locking means and a secondary cylinder, allows for precise adjustment and high force transfer to the electrode holder arms, enabling optimal welding positions and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a fluid actuator with main piston and secondary cylinder is used, then the force transfer to electrode holder arms is improved, but the device complexity increases
Solution Approach 1:
The auxiliary cylinder is nested within the main piston unit, with the auxiliary piston positioned inside the main cylinder chamber. This nested configuration allows the actuator to achieve high force multiplication through staged piston arrangements while minimizing the overall device footprint and structural complexity.
Solution Approach 2:
The actuator utilizes fluid pressure transmitted through the main cylinder and auxiliary cylinder to generate and amplify force. The one-way valve system controls fluid flow direction to enable precise force application to the electrode holder arms, achieving high force transfer through hydraulic/pneumatic mechanisms rather than direct mechanical transmission.
2Reliability
If locking means are added to lock the auxiliary piston, then the reliability of electrode holder arm control is improved, but the device complexity increases
Solution Approach 1:
The locking means are designed to automatically engage and disengage based on the position and movement of the auxiliary piston. The locking mechanism utilizes the piston's own movement to trigger the locking action, eliminating the need for external control systems or additional actuators, thereby enhancing reliability while minimizing added complexity.
Solution Approach 2:
The locking means provide dynamic locking capability that activates only when needed during the actuator's operation cycle. The locking mechanism transitions between locked and unlocked states based on operational requirements, allowing the system to maintain reliability during critical phases while remaining flexible and adaptable during other phases.
3Manufacturing precision
If a one-way valve system is implemented for fluid flow control, then the manufacturing precision of welding positions is improved, but the device complexity increases
Solution Approach 1:
The one-way valve system provides automatic feedback control for fluid flow direction based on the pressure differential and flow direction. The valves automatically open or close depending on the pressure conditions, ensuring precise control of fluid transmission to the pistons without requiring external sensors or control systems, thereby achieving high welding position precision with minimal added complexity.
Solution Approach 2:
The one-way valves act as intermediary elements between the fluid source and the pistons, mediating the fluid flow to ensure unidirectional transmission and prevent backflow. This intermediary mechanism enables precise control of piston movement and electrode holder arm positioning by controlling fluid flow direction and pressure transmission.
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
The actuator provides reliable and precise control over the electrode holder arms, enabling high-quality welds by allowing precise adjustment and efficient force transfer, suitable for both 'fulcrum' and 'slide' structured welding guns.
Implementation Method 1
the chamber of the auxiliary cylinder communicates, on a first side of the auxiliary piston opposite to said at least one secondary cylinder, with the chamber of the main piston through at least one one-way valve that is adapted to allow said fluid to flow from the chamber of the auxiliary cylinder to the chamber of the main piston
Implementation Method 2
the locking means of the invention are associated with the auxiliary cylinder to lock the auxiliary piston with respect to the auxiliary cylinder in its end-of-stroke position
Implementation Method 3
a main piston unit that is axially and slidably mounted in a chamber of the main cylinder, which main piston unit comprises an auxiliary cylinder in the chamber of which an auxiliary piston is axially slidably mounted
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A fluid actuator, particularly for controlling the relative movement of the electrode holder arms of a resistance spot welding gun, comprises a body including a main cylinder (24) provided with a main rod (28) the first end (30) of which projects outside the body to control the relative movement of the electrode holder arms (20a, 20b), and at least one secondary cylinder (26, 26a, 26b) in the chamber of which (44, 44a, 44b) a secondary piston, fixed to a respective rod (48) is axially slidable (46, 46a, 46b). The main rod (28) is associated with an axial main piston unit (40) slidable in a chamber (42) of the main cylinder (24), which comprises an auxiliary cylinder (38) in the chamber (36) of which is axially and slidably mounted one auxiliary piston (34) fixed to a second end (32) of the main rod (28). Locking means (54, 62) are associated with the auxiliary cylinder (38), to lock the auxiliary piston (34) with respect to the auxiliary cylinder (38) in the end-of-stroke position opposite to said at least one secondary cylinder (26, 26a, 26b).