Needle-equipped Outer Tube Welding with Controlled Force
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Solution Overview
Problem
The existing methods for manufacturing needle-equipped outer tubes, such as thermal welding, often result in cracks due to uneven heating and deformation of the joint member, leading to unreliable welds and potential structural weaknesses.
Innovation Solution
A method involving a preheating step where the distal end connecting section of the outer tube is heated to a temperature below its softening point with the joint member inserted, followed by a controlled thermal welding step using a pressing force of 4 N to 30 N to ensure a reliable bond without deforming the joint member's distal end, utilizing thermoplastic resins with compatibility for enhanced joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal welding is applied to the entire joint member, then welding reliability is improved, but the distal end portion deforms due to overheating
Solution Approach 1:
The patent applies thermal welding only to specific local regions of the joint member rather than the entire surface. The heating section is positioned to heat only the middle section and proximal end section of the joint member, deliberately excluding the distal end portion from thermal treatment. This localized heating approach ensures reliable welding at the connection interfaces while preventing deformation of the needle-bearing distal end portion.
Solution Approach 2:
The patent performs preliminary positioning of the needle in the distal end portion before thermal welding begins. By pre-assembling the needle in its final position and securing it temporarily, the patent ensures that the distal end portion remains structurally stable during the subsequent thermal welding process, preventing any thermal-induced deformation that would compromise needle alignment.
2Shape
If the heated area is restricted to avoid distal end softening, then deformation is prevented, but welding coverage becomes insufficient
Solution Approach 1:
The patent implements differentiated heating zones with distinct temperature profiles. The middle section and proximal end section receive intensive heating at temperatures sufficient for complete thermal welding, while the distal end portion is deliberately excluded from this high-temperature zone. This spatial variation in thermal treatment ensures both adequate welding coverage at critical interfaces and shape preservation of the distal end.
Solution Approach 2:
The patent divides the joint member into distinct functional segments: a needle-receiving distal end portion that requires shape preservation, and middle/proximal sections that require comprehensive welding. The heating apparatus is configured to apply thermal energy selectively to specific segments, creating a segmented thermal treatment strategy that addresses the different requirements of each region.
3Ease of manufacture
If adhesive joining is used, then manufacturing simplicity is improved, but joint strength is reduced
Solution Approach 1:
The patent replaces chemical bonding (adhesive joining) with thermal welding, a process-based joining method. By using controlled thermal energy to melt and fuse the thermoplastic materials of the joint member and outer tube, the patent achieves superior joint strength compared to adhesive methods. The thermal welding process creates a monolithic fused structure that eliminates the weak interface inherent in adhesive bonds.
4Ease of operation
If press insertion of joint member is used, then assembly ease is improved, but connection reliability is reduced
Solution Approach 1:
The patent utilizes the phase transition of thermoplastic materials from solid to molten state during thermal welding. By heating the joint member and outer tube to temperatures above their softening points, the materials transition to a viscous state that allows intimate molecular contact and fusion. Upon cooling, the materials re-solidify forming an extremely strong permanent bond, far superior to mechanical press-fit connections.
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 crack formation in the contact section, ensuring a strong and reliable bond between the joint member and the outer tube, as evidenced by reduced phase differences in birefringence measurements, thereby improving the structural integrity and usability of the needle-equipped outer tube.
Implementation Method 1
heating the distal end connecting section to a temperature at or below a softening point of a material forming the outer tube member
Implementation Method 2
thermally welding the joint member to the distal end connecting section of the outer tube member
Data Source
AI summary
A method of manufacturing a needle-equipped outer tube includes a preheating step comprising heating a distal end connecting section to a temperature at or below a softening point of a material forming an outer tube member with a joint member inserted in a distal end connecting section of the outer tube member, and with a needle being inserted or inserted and fixed in the needle insertion hole; and a joint member welding step, performed after the preheating step, comprising thermally welding the joint member to the distal end connecting section of the outer tube member with a distal end portion of the joint member pressed toward the proximal end of the joint member by a pushing member with a pressing force in a range of 4 N to 30 N.