Fastener Feeder Delay Mechanism for Nail Jam Prevention
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Solution Overview
Problem
Existing fastener driving tools face issues with unreliable timing relationships between the drive piston and feeder mechanism, leading to nail jams, misalignment, and improper driving due to insufficient pneumatic power and premature actuation of the feed piston.
Innovation Solution
The implementation of an electromechanical retention device and control module that ensures the drive piston returns to its pre-firing position before the feeder mechanism advances a nail, using a gas conduit to provide sufficient pneumatic force and an electromagnet to retain the feed piston until the drive piston has returned, thus delaying the actuation of the feeder mechanism until the driver blade has impacted the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the feed piston is actuated prematurely to advance the fastener, then the fastener can be positioned for driving, but the fastener becomes misaligned or jammed in the tool nose
Solution Approach 1:
The spring-biased feeder mechanism performs preliminary action by continuously maintaining the fastener in an advanced position within the tool nose, ready for immediate driving. The spring keeps the feed piston and associated mechanism in a state that pre-positions the fastener, so when the driver blade is ready, the fastener is already in the correct position without requiring additional actuation that could cause misalignment.
Solution Approach 2:
The system uses feedback from the driver blade's position and the fastener's state to control the feeding mechanism. The feedback mechanism ensures that the feed piston is actuated only when necessary and in the correct sequence relative to the driver blade's movement, preventing premature actuation that would cause misalignment while maintaining efficient fastener positioning.
2Reliability
If the feed piston is actuated late or insufficiently, then fastener misalignment is reduced, but the fastener driving process is delayed or unreliable
Solution Approach 1:
The spring-biased mechanism performs preliminary positioning of the fastener continuously, so when the driver blade is ready for impact, the fastener is already advanced into the correct position. This eliminates delays while maintaining reliability, as the fastener is pre-positioned without requiring late actuation that could cause misalignment.
Solution Approach 2:
The spring-biased feeder mechanism maintains continuous useful action by constantly maintaining the fastener in an advanced, ready position. The spring keeps the feed piston engaged with the fastener strip, ensuring continuous positioning without interruption or delay, thereby maintaining high productivity while avoiding the misalignment problems of premature actuation.
3Reliability
If sufficient pneumatic power is supplied to the feed piston, then the feeding mechanism operates reliably, but the drive piston return is slowed or prevented
Solution Approach 1:
The pneumatic power supply is segmented into separate pathways: one for actuating the feed piston and another for the drive piston return. The feed piston receives pneumatic power through a dedicated conduit that is timed to activate only when the drive piston is in the correct position, preventing interference with the drive piston's return motion while maintaining reliable feeding operation.
Solution Approach 2:
The system uses dynamic timing control to regulate pneumatic power delivery to the feed piston. The pneumatic actuation is activated only when the drive piston has completed its downward stroke and is beginning to return, creating a dynamic sequence that prevents interference with the drive piston's return speed while ensuring reliable fastener feeding.
4Reliability
If the feed piston acts on the fastener during drive piston return, then fastener positioning is maintained, but friction loads the driver blade and prolongs return
Solution Approach 1:
The system dynamically adjusts the feed piston's engagement timing to match the drive piston's position. The feed piston is actuated only when the drive piston has completed its downward stroke and is beginning to return, creating a dynamic timing relationship that maintains fastener positioning without applying friction loads to the driver blade during its return motion.
Solution Approach 2:
The spring mechanism acts as an intermediary that decouples the feed piston's positioning function from the drive piston's return motion. The spring maintains the fastener in position through elastic force independent of the drive piston's movement, eliminating direct frictional interaction between the feed mechanism and driver blade during return.
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 reduces nail malfunctions, improves piston return speed and reliability, increases operational life, and prevents fastener misalignment, resulting in more effective and efficient fastener driving with reduced wear and increased energy efficiency.
Implementation Method 1
a gas conduit is placed in fluid communication with the main drive cylinder of the power source. Upon ignition and combustion, as the drive piston attached to the driver blade travels down the cylinder toward the fastener or nail to be driven, a supply of combustion gas is distributed into the gas conduit and is used to operate a spring-biased feeder mechanism. The gas pressure overcomes a biasing force provided by a spring
Implementation Method 2
an electromagnet for retaining the feed piston in the retracted position until the drive piston has returned to its pre-firing position
Data Source
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AI summary
A fastener driving tool includes a power source including a cylinder, a piston with a driver blade reciprocating in the cylinder, a tool nose associated with the power source for receiving the driver blade for driving fasteners fed into the nose, and a magazine housing a supply of the fasteners. A magazine feeder mechanism is associated with the magazine for sequentially feeding fasteners into the nose, and the feeder mechanism includes a reciprocating feed piston. A conduit is connected between a port in the cylinder and the feed mechanism for diverting combusted gas for activating the feed piston. The port is disposed in the cylinder a specified distance below a piston prefiring position, and the distance is reflective of a delay of feeding the gas to the feed piston at least until engagement between an end of the driver blade and a head of a fastener in the tool nose.