Multi-Stage Pump Casing Welding Layout Against Side Plate Peeling
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Solution Overview
Problem
The existing centrifugal pumps with trim edges experience a large pressure drop in the gap between the side plate and the main plate, leading to a tensile force that can cause the side plate to peel off from the return vanes due to differential pressure, resulting in damage.
Innovation Solution
The casing design concentrates welding points for securing return vanes to the side plate near the center of the vane, with specific positioning and spacing to enhance bonding strength, ensuring the side plate is securely attached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If trim edge portions are added to the impeller main plate to reduce axial thrust force, then bearing wear is reduced and lifespan is extended, but a large pressure drop occurs in the gap between the side plate and main plate, generating tensile force that can cause the side plate to peel off from the return vanes
Solution Approach 1:
The patent applies local quality by concentrating the welding points in specific locations on the return vanes - specifically at the outer peripheral portions and at positions corresponding to the trim edge portions. This non-uniform distribution of welding points creates localized areas of enhanced bonding strength precisely where the tensile forces are most likely to cause peeling, rather than uniformly distributing welding points across all return vanes.
Solution Approach 2:
The patent implements preliminary action by strategically positioning welding points in advance at locations that will experience the highest stress from the pressure drop. The welding points are pre-positioned at the outer peripheral portions of the return vanes and at positions corresponding to the trim edge portions, preparing the structure to resist the tensile forces that will be generated when the impeller with trim edges operates.
2Strength
If welding points are distributed across the entire surface of return vanes, then bonding coverage is maximized, but manufacturing complexity and welding time increase
Solution Approach 1:
The patent applies local quality by concentrating the welding points in specific locations on the return vanes - specifically at the outer peripheral portions and at positions corresponding to the trim edge portions. This non-uniform distribution of welding points creates localized areas of enhanced bonding strength precisely where the tensile forces are most likely to cause peeling, rather than uniformly distributing welding points across all return vanes.
Solution Approach 2:
The patent implements partial action by applying welding only at the most critical locations where tensile forces are concentrated, rather than welding the entire surface of the return vanes. The welding points are strategically placed at the outer peripheral portions and at positions corresponding to the trim edge portions, providing sufficient bonding strength with fewer welding operations.
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 configuration effectively prevents damage to the side plate by maintaining strong bonding even under high tensile forces, enhancing the durability of the centrifugal pump.
Implementation Method 1
return vanes each of which has an arc-shape and is projection-welded to the back surface of the side plate at a plurality of welding points provided on an upper end surface
Data Source
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AI summary
The present invention relates to a casing of a centrifugal pump, and more particularly to a casing of a multi-stage centrifugal pump. The casing (7) includes a side plate (26) having a front surface facing to a back surface of a main plate (35) of an impeller (5), and return vanes (16) each of which has an arc shape and is projection-welded to the back surface of the side plate (26) at a plurality of welding points (PM1-PM4) provided on the upper end surface. The main plate (35) of the impeller (5) has trim edge portions (43) each of which is recessed radially inward, and the outermost welding point (PM4) farthest from the rotary shaft (1) among the plurality of welding points (PM1-PM4) overlaps at least partially with a projection point (PR1) which is projection of the outermost periphery (OM) of the impeller (1) onto the return vane (16), or is located radially inward of the projection point (PR1).