Injection Molding Screw Guide Stability Against Tie-Bar Deformation
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Solution Overview
Problem
Conventional injection molding machines experience unstable screw movement due to longitudinal deflection caused by reactive forces during material injection, leading to potential bending or loss of parallelism in guide members, which affects the reliability of screw operation.
Innovation Solution
The injection molding machine design includes a frame with lateral members and guide members that secure one end of the supporting members to the frame and allow the other end to move relative to the lateral members, maintaining linearity and stability even under deformation from reactive forces, ensuring smooth screw movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If guide members are rigidly fixed to lateral members, then positioning precision is improved, but the system becomes vulnerable to deformation from reactive forces during injection
Solution Approach 1:
The supporting member is designed with a movable portion that can move along the lateral member axis, transforming the rigid fixing system into a dynamic one. This allows the supporting member to absorb deformation from reactive forces during injection while maintaining guide member linearity, thus resolving the contradiction between positioning precision and reliability
Solution Approach 2:
The system changes the degree of freedom parameter by allowing the movable portion to move along the lateral member. This parameter change enables the guide members to maintain their parallelism and linearity even when the lateral members deform under reactive forces, simultaneously achieving both precision and reliability
2Ease of operation
If the motor and screw rear end are mounted far from the support point, then operational flexibility is improved, but longitudinal deflection increases causing unstable screw movement
Solution Approach 1:
The supporting member acts as an intermediary between the screw rotation mechanism and the lateral members. It provides a stable reference frame for the guide members while allowing the screw rotation mechanism to be positioned for operational flexibility, thus reducing deflection and improving stability without sacrificing ease of operation
Data Source
AI summary
A screw is moved along an axis by a screw advancement-retraction mechanism. A screw rotation mechanism is supported for movement along the axis by a pair of supporting members, each includes a rail for use as a guide member. The supporting members are arranged individually along tie-bars for use as lateral members and extend parallel to the tie-bars. One longitudinal end portion of each supporting member is secured to a frame of an injection unit by a fixing portion including a fixing member. The other end portion of the supporting member is supported on each tie-bar by a movable portion including a sliding member. The sliding member is movable along an axis of the tie-bar. With this arrangement, deformation, if any, of the tie-bar is prevented from affecting the rail, so that the screw rotation mechanism and the screw can move steadily.