Needle-equipped Outer Cylinder Heat-welding Segmentation
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Solution Overview
Problem
Existing methods for manufacturing needle-equipped outer cylinders, such as those used in insulin and vaccine injectors, face challenges with heat-welding techniques, where the joining member can deform and fail to securely attach to the outer cylinder, leading to reliability issues and potential cracking due to non-heat-welded portions and molding differences.
Innovation Solution
A needle-equipped outer cylinder design featuring a joining member with a tapered portion and an outer cylinder with a distal end joint, where the joining member is inserted and heat-welded to the outer cylinder's projection, ensuring a stable and secure attachment without deforming the distal end, using a method that includes preheating and precise heat-welding to prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat-welding is applied to the entire joining member including the distal end, then the joining member can be securely attached to the outer cylinder, but the distal end portion deforms and becomes larger than the inner cavity opening, preventing proper insertion and welding
Solution Approach 1:
The joining member is divided into two distinct zones: a distal end portion that remains unheated and maintains its original shape for insertion, and a proximal portion that is heat-welded to the outer cylinder for secure attachment. This segmentation allows each zone to serve its specific function without interference from the other.
Solution Approach 2:
Heat treatment is applied locally only to the proximal portion of the joining member, while the distal end portion is excluded from heating. This localized quality change ensures that the distal end maintains its original dimensions for proper insertion into the inner cavity, while the proximal portion achieves sufficient thermal softening for reliable welding to the outer cylinder.
2Strength
If heat-welding is applied to the joining member, then attachment strength is improved, but non-heat-welded portions and molding differences cause cracking to occur
Solution Approach 1:
The distal end portion of the joining member is pre-formed with a shape and dimensions that enable proper insertion into the inner cavity before heat-welding occurs. This preliminary shaping ensures that the critical insertion interface is established before any thermal processing that could cause deformation or cracking.
Solution Approach 2:
The joining member is segmented into a heat-welded proximal portion and a non-heat-welded distal portion, allowing the distal end to avoid thermal stress and molding variations that cause cracking, while still achieving secure attachment through welding of the proximal portion to the outer cylinder.
3Force
If the joining member is pressed during heat-welding, then welding pressure is improved, but the already softened distal end deforms and cannot enter the tapered inner cavity
Solution Approach 1:
The joining member is segmented into a pressed proximal portion and an unpressed distal portion during heat-welding. The distal end is excluded from pressing forces, maintaining its original shape for insertion, while the proximal portion receives adequate pressing pressure for reliable welding to the outer cylinder.
Solution Approach 2:
Mechanical pressing is applied locally only to the proximal portion of the joining member during heat-welding, while the distal end portion is protected from pressing forces. This localized pressing ensures adequate welding pressure where needed without deforming the insertion-critical distal end.
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 design enhances the reliability and stability of the heat-welding process, preventing cracking and ensuring a secure attachment between the joining member and the outer cylinder, while maintaining the integrity of the needle-equipped assembly.
Implementation Method 1
heat-welding the joining outer peripheral portion to an inner peripheral surface of the distal end joint of the outer cylinder and an outer peripheral surface of the needle tube by allowing the needle tube to generate heat by a heat generating device
Data Source
AI summary
A needle-equipped outer cylinder includes: a needle tube; a joining member comprising: a needle tube accommodation hole that accommodates a proximal end side portion of the needle tube and penetrates the joining member from a distal end of the joining member to a proximal end of the joining member, and a joining outer peripheral portion provided on an outer peripheral portion of the needle tube accommodation hole; and an outer cylinder member comprising: a distal end joint that comprises an inner cavity that receives the joining outer peripheral portion of the joining member from a distal end side, and a projection located at a proximal end portion of the inner cavity and projecting into the inner cavity. The joining member comprises, at a proximal end portion of the joining member, an abutment portion that abuts the projection of the outer cylinder member.