External Groove Rolling for Coated Metal Tube Ends
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Solution Overview
Problem
Existing devices for creating circumferential grooves in metal pipes for accommodating pipe connectors often impair the internal surface, making it difficult to form an effective corrosion-inhibiting layer, especially in fire extinguishing systems where corrosion resistance is critical.
Innovation Solution
A device with a first, rotationally driven roller and a second, freely rotating roller is used, where the driven roller is placed on the outer surface to create the groove, avoiding contact with the internal surface, and the rollers are aligned to ensure the structuring is outside the coated area, allowing for smooth internal coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the driven roller with structured surface is placed inside the pipe to create the groove, then sufficient static friction is generated to rotate the pipe and press the groove, but the structured surface imprints a negative structure into the pipe wall, creating surface irregularities that impair subsequent internal coating and corrosion resistance
Solution Approach 1:
The invention inverts the conventional approach by placing the driven roller with structured surface on the outside of the pipe instead of inside. The roller rotates the pipe from the outside and presses the groove into the pipe wall, causing the structured surface to imprint on the outer surface rather than the inner surface. This inversion eliminates the harmful effect of surface irregularities on internal coating while maintaining the necessary friction force for groove formation.
2Manufacturing precision
If high contact forces are applied between the rollers to press the groove into the pipe wall, then the groove quality and connector compatibility are improved, but the structured surface of the driven roller imprints deeper negative structures into the pipe wall, worsening the surface irregularity
Solution Approach 1:
By inverting the position of the driven roller to the outside of the pipe, the invention allows high contact forces to be applied for groove formation without transferring surface irregularities to the internal surface. The imprinted negative structure appears only on the outer surface, which does not affect internal coating quality or corrosion resistance.
3Object-affected harmful factors
If the driven roller is placed on the outside of the pipe, then the internal surface remains smooth for proper coating application, but the roller must be moved transversely to the pipe axis to achieve groove pressing
Solution Approach 1:
The pressing device is designed with dynamic capabilities to move the driven roller transversely to the pipe axis during rotation. This dynamic positioning allows the roller to press the groove into the pipe wall while maintaining external contact. The transverse movement is controlled and reversible, enabling the roller to be repositioned for different groove locations without compromising the simplicity of the overall device.
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 approach prevents surface irregularities from interfering with the coating process, enhancing the corrosion resistance and connector compatibility while maintaining groove quality.
Implementation Method 1
The structured surface of the driven roller, necessary to generate sufficient static friction, can, under sufficiently high contact forces
Implementation Method 2
a contact force is exerted on the metal pipe, which makes it possible to press a groove into the pipe by deforming the metal pipe
Data Source
Figure 1~2
AI summary
The invention relates to an apparatus (1) for producing a peripheral groove (101) in an end portion (103) of a metal tube (100), in particular a metal tube (100) that is to be coated on the inside, wherein the groove (101) is designed for receiving pipe connectors, comprising a first, rotationally driven roller (3), a second, freely rotating roller (5), wherein the first roller (3) has a roughened or structured surface (6) in relation to the second roller (5), a pressing device (15) for producing a relative movement between the first and second rollers (3, 5), between a first position and a second position, wherein the rollers (3, 5) in the first position assume a first distance from one another that allows a wall of the tube to be introduced between the rollers (3, 5), and in the second position assume a smaller, second distance from one another, which is smaller than a material thickness (M) of the wall of the tube. According to the invention, it is proposed that the first, driven roller (3) is designed to take up the tube from outside in the second position and rotate it such that, when the first roller (3) is driven, a peripheral groove (101) is pressed into the tube in the second position.