C-Shaped Frame Absorbs Forces in Tie-Bar-Less Injection Molding

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Solution Overview

Problem

Existing injection molding machines face limitations in mold size due to tie bars and require costly solid machine frames to prevent bending, while tie-bar-less machines need complex mechanisms for parallelism and force distribution.

Innovation Solution

A closed frame system with side walls and cross members absorbs forces from both the clamping and injection units, eliminating the need for additional fastening devices and allowing for flexible stabilization and adjustment, thereby reducing costs and ensuring parallelism without additional mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a C-shaped machine frame is used in tie-bar-less injection molding machines, then accessibility of the space between mold platens is improved, but the machine frame requires costly solid construction to prevent bending under clamping force

Engineering Contradiction:
Improveaccessibility of space between mold platensVSAvoidsolid construction of machine frame
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The machine frame is segmented into a C-shaped frame structure with distinct functional zones. The C-shaped frame separates the clamping unit and injection unit into different spatial regions, allowing independent optimization of each unit while maintaining overall structural integrity. This segmentation enables accessibility to the mold platen space without requiring a completely solid frame construction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The machine frame employs composite structural design combining the C-shaped frame with strategic reinforcement elements. Rather than using uniformly solid construction throughout, the frame uses composite structural approaches where reinforcement is applied only where necessary to resist bending moments, reducing overall material usage and cost while maintaining structural adequacy.

Inventive Principle:
Principle #40Composite materials

2Force

If four cylindrical tie bars are used to transmit closing force, then force transmission is improved, but the size of molds is limited due to space occupied by bars between platens

Engineering Contradiction:
Improveforce transmission of closing mechanismVSAvoidsize of molds
Core Design Contradiction:
ForceVSArea of stationary object

Solution Approach 1:

The tie bars are extracted from the space between the mold platens and repositioned to the exterior of the mold area. The C-shaped frame structure allows the closing mechanism's force transmission elements to be located outside the mold envelope, completely eliminating the space occupation problem that limited mold size in conventional four-tie-bar designs.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The force transmission function is moved from the vertical dimension (between platens) to the horizontal dimension (external to mold area). By repositioning the tie bars or equivalent force transmission elements to the exterior of the mold space, the design utilizes horizontal space rather than vertical space, thereby maximizing the available mold area between platens.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If tie-bar-less design is used, then accessibility is improved, but complex mechanisms are required to ensure parallelism between mold platens

Engineering Contradiction:
Improveaccessibility of mold platen spaceVSAvoidmechanisms for ensuring parallelism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The C-shaped frame structure serves multiple functions simultaneously: it provides the structural support for the clamping unit, houses the injection unit, ensures parallelism of the mold platens through its inherent rigidity, and maintains accessibility to the mold space. This multi-functionality eliminates the need for separate complex parallelism adjustment mechanisms that would otherwise be required.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The C-shaped frame structure is designed to self-maintain platen parallelism through its inherent geometric stability and rigid construction. The frame's structural characteristics automatically ensure parallelism without requiring active control systems, adjustment mechanisms, or complex mechanical devices, allowing the structure to serve its own alignment requirements.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2212085B1Injection molding machine having a force-absorbing closed system
Publication Date: 2018.07.18 ZHAFIR PLASTICS MACHINERY
  • EP2212085B1 patent drawingFigure 1
  • EP2212085B1 patent drawingFigure 2
  • EP2212085B1 patent drawingFigure 3

AI summary

The invention relates to an injection molding machine (110) having a closing unit (100) and an injection unit (101), wherein a frame having side walls (1) and traverses (5, 14) connecting the side walls (1) to one another absorbs the forces of the closing unit (100) as a closed system and/or wherein a frame having side walls (1) and traverses (5, 14) connecting the side walls (1) to one another absorbs the forces of the injection unit (101) as a closed unit.