Lockbolt Installation Tool Venting for Vacuum-Free Pull Stroke
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Solution Overview
Problem
Current lockbolt installation tools experience reduced performance due to oil loss leading to vacuum conditions and incomplete engagement of tool jaws, increasing the risk of tool and lockbolt failure, which is exacerbated by the complexity and cost of secondary hydraulic circuits.
Innovation Solution
The use of floating pistons with a vent to atmosphere and an integrated oil reservoir within the tool, along with a seal and small diameter aperture on the pneumatic piston, ensures compliance and maintains pressure balance, preventing vacuum conditions and reducing tool complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed volume hydraulic lines are used in the double-acting pneumatic piston, then the tool structure is simple, but oil loss causes vacuum conditions and reduced tool performance
Solution Approach 1:
The patent applies the dynamics principle by making the hydraulic line volumes variable rather than fixed. The first and second hydraulic lines are designed with adjustable volumes that can change during operation, allowing the system to compensate for oil losses and maintain proper pressure balance throughout the cycle, thereby preventing vacuum conditions while keeping the overall structure relatively simple.
Solution Approach 2:
The patent implements parameter changes by varying the volume of hydraulic lines during different phases of the tool cycle. The first hydraulic line has a larger volume during the pull stroke and a smaller volume during the return stroke, while the second hydraulic line has the opposite volume characteristics. This dynamic parameter adjustment compensates for oil losses and maintains system reliability.
2Reliability
If an oil reservoir and pressure relief valve are added to provide secondary hydraulic volume, then tool reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent merges the functions of multiple hydraulic lines into the existing double-acting pneumatic piston structure. Instead of adding a separate oil reservoir and pressure relief valve system, the invention integrates variable volume hydraulic lines directly into the piston, combining the hydraulic compensation function with the existing mechanical structure and reducing overall device complexity.
Solution Approach 2:
The double-acting pneumatic piston is designed to serve multiple functions: it acts as both the actuator for the tool cycle and the housing for the variable volume hydraulic lines. This multi-functionality eliminates the need for separate hydraulic compensation components, reducing device complexity while maintaining reliability.
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 solution maintains full engagement of tool jaws with the lockbolt stem, reduces the risk of tool and lockbolt failure, and decreases tool complexity, bulk, and cost by eliminating the need for secondary hydraulic circuits.
Implementation Method 1
floating pistons to provide compliance when transmitting pressure from the double acting pneumatic piston to the head piston
Implementation Method 2
In the volume between the floating pistons, air is provided via a vent to atmosphere
Implementation Method 3
a seal is provided, which is fitted to the pneumatic piston, and acts to seal the air inlet / exhaust on the pull side when the pneumatic piston is at the end of the return stroke
Implementation Method 4
a small diameter aperture through the pneumatic piston is also provided. The aperture acts as an air bleed across the piston, i.e. between the pull and return sides of the pneumatic piston, thereby equalising the pressures on either side when the tool is at rest
Data Source
Figure 1~6
Figure 7a~7d
Figure 8~9
AI summary
A pneumatically powered fastener installation tool (2) comprising floating pull (24) and return (26) pistons which are free to move axially within the main channel (22), thereby providing compliance when transmitting pressure from a double- acting pneumatic piston (16) and intensifier rod (18) to a head piston (6) thereby to install a fastener such as a lockbolt and preventing the generation of a vacuum condition on oil loss during the pull stroke of the tool.