Pipe Grooving Cam Mechanism for Precise Groove and Flare Control
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Solution Overview
Problem
Existing roll grooving machines face challenges in accurately producing circumferential grooves in pipe elements with precise tolerances, often resulting in flare and requiring significant torque and operator intervention, which complicates the design and manufacture of mechanical couplings and seals.
Innovation Solution
A device using a pinion with a rotating carriage and cam bodies with specific cam surfaces and traction surfaces, along with an expanding die, to form circumferential grooves in pipe elements with minimal torque and operator involvement, ensuring accurate groove formation and controlling flare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If roll grooving machines are used to cold work pipe elements, then circumferential grooves can be formed to accept mechanical pipe couplings, but the groove radius precision and tolerance control deteriorate
Solution Approach 1:
The cam body is segmented into multiple cam surfaces (first cam surface with increasing radius, second cam surface with constant radius) that work in sequence. This segmentation allows precise control of the groove formation process in stages: first creating the groove shape, then controlling the flare, thereby achieving precise groove radius while maintaining relatively simple device structure
Solution Approach 2:
The first cam surface performs preliminary action by creating the circumferential groove shape before the second cam surface controls the flare. This preliminary groove formation with controlled geometry precedes the flare control action, ensuring that the groove radius precision is established before final dimensional control is applied
2Manufacturing precision
If roll grooving machines impress circumferential grooves near the end of pipe elements, then grooves can be formed in desired locations, but the end region of the pipe element expands in diameter causing flare
Solution Approach 1:
The second cam surface with constant radius performs preliminary anti-action by controlling and limiting the flare that occurs during groove formation. It counteracts the natural expansion tendency of the pipe end material during the grooving process, maintaining the pipe end shape within acceptable tolerances while allowing precise groove formation at the desired location
3Productivity
If prior art roll grooving machines are used, then grooves can be formed, but significant torque is applied to the pipe element and production rates are low
Solution Approach 1:
The cam mechanism employs periodic action where the cam bodies rotate in synchronization with the pipe element, applying force in a rhythmic, periodic manner rather than continuous high torque. The cam surfaces engage and disengage periodically during rotation, creating efficient cyclic loading that reduces overall torque requirements while maintaining high production rates through continuous operation
Solution Approach 2:
The cam surfaces utilize curved, spheroidal geometry to distribute contact forces over larger areas and redirect applied forces through optimized load paths. The curved cam surfaces convert rotational motion into controlled radial forces, reducing the peak torque required compared to linear or flat contact mechanisms, thereby enabling higher production rates with lower torque application
4Ease of operation
If prior art devices require actuators for forcing rollers into engagement and operator adjustment of roller travel, then groove formation can be achieved, but operator involvement increases and simplicity is reduced
Solution Approach 1:
The cam mechanism is designed to be self-servicing where the cam bodies automatically engage the pipe element and apply the necessary forming forces through their geometric profiles during rotation. The device self-regulates the groove formation process without requiring external actuators or operator adjustments, achieving ease of operation while maintaining relatively simple device structure through pure geometric mechanisms
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 device achieves precise and efficient formation of circumferential grooves with minimal torque application, reducing operator involvement and improving production rates by using a pinion with a rotating carriage and cam bodies with specific cam surfaces and traction surfaces, effectively addressing the challenges of flare and tolerance issues.
Implementation Method 1
cold working of pipe elements, for example, impressing a circumferential groove in a pipe element
Implementation Method 2
An expanding die is positioned adjacent to the pinion and concentric with the pinion axis. The expanding die has a plurality of die segments movable radially toward and away from the pinion axis
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A device for forming circumferential grooves in pipe elements uses multiple geared cam bodies mounted on a carriage which rotates about a fixed pinion. The gears engage with the pinion which causes the geared cam bodies to rotate relative to the carriage. Traction surfaces and cam surfaces on the cam bodies traverse the outer surface of the pipe element and impress a circumferential groove therein. To substantially prevent rotation of the pipe element the pitch circle diameter of the pinion equals the outer diameter of the pipe element and the pitch circle diameters of the traction surfaces equal the pitch circle diameters of the gears.