Plate Laminate Heat Exchanger Pin Fixing for Accurate Brazing
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Solution Overview
Problem
Existing plate laminate heat exchangers face challenges with complex manufacturing processes, displacement of plates during brazing, and poor joining due to shrinkage issues, particularly when using restraining systems like grooved spring pins.
Innovation Solution
A novel plate laminate heat exchanger design where at least one adjacent plate is clad with a brazing material, featuring a thin and long fixing pin or plate that is expanded at one end to fit into a round hole or cutout, allowing temporary fixation without restraining shrinkage, thus preventing displacement and ensuring accurate assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pin for fixing is wholly restrained to prevent displacement during brazing, then plate displacement is prevented, but shrinkage by baking is restrained causing poor joining and deterioration in flatness
Solution Approach 1:
The fixing pin is segmented into two functional zones: an expanded distal end that prevents plate displacement during brazing, and a slender proximal end that allows free shrinkage by baking. This segmentation enables the pin to simultaneously provide mechanical restraint and thermal contraction freedom, resolving the contradiction between positioning accuracy and joining quality.
Solution Approach 2:
Different portions of the fixing pin have different structural properties: the distal end features an expanded diameter for rigid fixation and displacement prevention, while the proximal end maintains a slender profile for flexible shrinkage accommodation. This local quality differentiation allows the single component to satisfy both contradictory requirements of stable positioning and free thermal contraction.
2Reliability
If a grooved spring pin is used to relieve restraint in shrinkage by baking, then shrinkage restraint is reduced, but molten brazing material intrudes inside the pin increasing shrinkage by baking and adding cost
Solution Approach 1:
The harmful grooves are completely removed from the fixing pin structure. Instead of using a grooved spring pin that allows brazing material intrusion, the invention employs a smooth-bored pin with selective diameter expansion. This extraction of the grooved feature eliminates the source of brazing material intrusion while maintaining the necessary shrinkage freedom through the slender proximal end design.
Solution Approach 2:
The fixing pin is designed as a simple, inexpensive component made from common materials like aluminum or stainless steel, without complex grooved spring mechanisms. This simplified design reduces manufacturing cost and eliminates the problems associated with grooved pins, while still achieving the dual function of displacement prevention and shrinkage accommodation.
3Stability of the object's composition
If welding is used to fix outer peripheral part of laminated body, then temporary fixing is achieved, but manufacturing process becomes complex and welding marks remain in finished product
Solution Approach 1:
The mechanical welding process is replaced with a simpler insertion and expansion mechanism. The fixing pin is inserted through aligned holes in the laminated plates and then expanded at its distal end to provide mechanical restraint. This mechanical substitution eliminates the complexity of welding operations and avoids leaving unsightly welding marks on the finished product.
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 simplifies the manufacturing process, prevents plate displacement during brazing, and maintains structural accuracy and flatness by allowing for both temporary fixing and non-restraint of shrinkage, resulting in a cost-effective and structurally excellent heat exchanger.
Implementation Method 1
the fixing pin is expanded only in an outer diameter at one end part in a longitudinal direction thereof
Implementation Method 2
in a brazing process, there is generated decrease in dimension in the laminate direction due to melting and liquation of a brazing material
Data Source
AI summary
To provide a plate laminate type heat exchanger that is capable to be temporarily fixed easily and surely before brazing assembly and can be fabricated with good accuracy. In a plate laminate type heat exchanger using a cladding material cladded with a brazing material, in each of laminated plates, a round hole penetrating in a laminate direction is formed; a thin and long fixing pin is inserted into the round hole so as to communicate each of plates; the fixing pin is fixed to the round hole by expansion of the outer diameter only at one end part in the longitudinal direction of the fixing pin; and each of plates is temporarily fixed integrally.