Twin-Screw Extruder Barrel Block Joint for Uniform Contact Pressure
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Solution Overview
Problem
In twin-screw extruders, the existing flanged joints can lead to uneven contact between barrel blocks, resulting in low contact pressure and material leakage due to the falling of flanges during bolt fastening, which prevents uniform contact and causes raw materials to leak from the gaps between the blocks.
Innovation Solution
The barrel blocks are designed with a rectangular parallelepiped shape, featuring first and second flanges with specific bolt holes and a recessed joint structure that ensures tight and uniform contact between adjacent blocks, preventing material leakage by maintaining consistent contact pressure through the use of bolts and nuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If flanged joints are used to join barrel blocks, then the barrel blocks can be connected together, but the flanges may fall during fastening causing uneven contact and low contact pressure
Solution Approach 1:
The joint face is designed with a recessed structure (first flank face) that is prepared in advance before fastening. This recessed structure guides the mating flange to contact at the correct position, preventing flange falling during the fastening process and ensuring uniform contact pressure distribution from the beginning of assembly.
Solution Approach 2:
The joint structure transitions from a simple flat flange-to-flange contact to a three-dimensional recessed joint face structure. The first flank face creates a stepped configuration where the joint face is recessed relative to the flange outer periphery, adding a dimensional element that controls contact geometry and prevents uneven settling during fastening.
2Strength
If bolts are used to fasten the flanged joints, then the barrel blocks are secured together, but the flanges may fall according to fastening amount causing non-uniform contact state
Solution Approach 1:
The recessed first flank face structure is pre-formed on the joint face before fastening operations. This preliminary structural feature ensures that when bolts are tightened, the flanges are constrained to contact at the recessed joint face rather than allowing them to fall or settle unevenly, maintaining consistent contact state throughout the fastening process.
Solution Approach 2:
The recessed first flank face acts as an intermediary structure between the two flanges. It mediates the contact interaction by providing a controlled geometric feature that distributes and equalizes the contact pressure, preventing direct uneven contact between flange surfaces during bolt fastening.
3Ease of manufacture
If simple flanged joints are used, then the structure is simple and easy to manufacture, but raw materials may leak from gaps between barrel blocks
Solution Approach 1:
The joint design adds a recessed dimensional feature (first flank face) to the otherwise simple flanged joint structure. This additional dimensional element creates a stepped configuration that enhances leak prevention by ensuring tight contact between mating surfaces, while still maintaining relative manufacturing simplicity through standard machining operations.
Solution Approach 2:
The recessed first flank face creates a localized quality enhancement at the joint face area. This local structural modification concentrates the contact pressure and improves sealing at the critical joint interface, while the rest of the flange structure remains relatively simple and easy to manufacture.
Data Source
AI summary
A barrel block for a twin-screw extruder constitutes a barrel including a cylinder and has joints at both ends. A first joint includes a first inner joint face on a peripheral edge of a first hole of an insertion hole for screws, and includes a first flank face and a first outer joint face on an outer periphery of the first inner joint face. The first outer joint face is located in the outer periphery of a plurality of first bolt holes. The first outer joint face is more recessed toward a second block end face than the first inner joint face.