Injection Mold Core Segmentation for Impeller Demolding
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Solution Overview
Problem
The production of impellers with curved blades for centrifugal pumps is hindered by complex and costly tools due to the need for multiple core parts to move along curved paths, leading to lengthy demolding times and increased maintenance.
Innovation Solution
A method involving a first linear-axial and a second axial-rotary relative movement to demold the impeller, using ejectors to push the impeller away from core parts, reducing the number of moving components and allowing for shorter travel distances, thus simplifying the injection molding tool and reducing production time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple core parts are moved along curved paths to demold impellers with curved blades, then the impeller can be successfully demolded, but the tool complexity and maintenance requirements increase significantly
Solution Approach 1:
The core is divided into multiple core parts (first core part and second core part) that can move independently. The first core part remains stationary while the second core part moves linearly along the axial direction, eliminating the need for complex curved path mechanisms. This segmentation allows the impeller to be demolded successfully while keeping the tool structure simple.
2Reliability
If multiple core parts are moved along curved paths to demold impellers, then complete demolding is achieved, but the demolding time increases due to limited movement speeds
Solution Approach 1:
The invention introduces a dynamic configuration where the second core part can move linearly along the axial direction independently of the first core part. This dynamic arrangement allows for faster demolding speeds compared to curved path movement, while still achieving complete separation of the impeller from the mold. The linear movement path is shorter and can be executed more quickly than curved paths.
3Manufacturing precision
If core parts are designed to engage with undercuts in curved flow channels, then the impeller geometry can be formed, but the number of moving components increases
Solution Approach 1:
Instead of moving both core parts along curved paths, the invention inverts the approach by keeping the first core part stationary and moving only the second core part linearly. The second core part is designed with a curved surface that matches the undercut geometry, allowing it to engage with the curved flow channel while moving in a simple linear path. This reduces the number of moving components from two to one.
Data Source
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AI summary
The invention relates to a method and a device for manufacturing an impeller (1), particularly for a centrifugal pump, by injection molding. The impeller has blades (2) curved in at least two spatial directions on a support disc (3) and flow channels (5) extending predominantly in a radial direction between them. Each flow channel is defined by at least two core parts (22, 23), of which a first core part (22) lies within the corresponding flow channel (5) without undercutting, and a second core part (23) engages with the flow channel (5) via an undercut. According to the invention, the first and second core parts (22, 23) of each flow channel (5) are arranged one behind the other in the circumferential direction. To demold the injection-molded impeller (1), a first linear-axial relative movement takes place between the first core parts (22) and the impeller (1).Subsequently, the impeller (1) is moved away from the second core parts (23) by a second relative movement in the axial direction, while simultaneously performing a rotational movement.