Knife-Flap Clamping Unit for Reliable High-Speed Film Stretching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing clamping units in stretching machines experience unreliable contactless opening and closing at high production speeds, leading to mechanical stress and reduced service life, especially in fast production lines for plastic films.
Innovation Solution
A clamping unit design with a knife flap having a longer head section and optimized geometry, combined with magnetic opening and closing devices, ensures reliable contactless operation even at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If magnetic opening and closing devices are used to prevent wear on clamping units, then contactless operation is achieved and service life is extended, but at high production speeds the opening rate decreases and reliability is insufficient
Solution Approach 1:
The patent changes the geometric parameters of the knife flap, specifically increasing the head section length to at least 50% longer than the neck section minimum length. This geometric parameter change increases the magnetic force by up to 35%, enabling reliable contactless opening and closing even at high production speeds exceeding 500m/min
Solution Approach 2:
The patent incorporates a pre-tensioning element (such as a spring) that pre-tensions the knife flap in the gripping position. This preliminary action ensures the knife flap is properly positioned and tensioned before the magnetic opening device acts on it, improving the reliability of contactless operation at high speeds
2Reliability
If mechanical positive opening/closing devices are used to ensure opening and closing, then reliable operation is achieved, but high mechanical stress and impact occur which significantly reduces service life
Solution Approach 1:
The patent replaces the mechanical positive opening/closing devices with an optimized magnetic opening and closing system. By increasing the head section length of the knife flap, the magnetic force is enhanced sufficiently to provide reliable contactless operation without the mechanical impact and stress that would reduce service life
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
The enhanced clamping unit design increases magnetic force by up to 35%, allowing reliable opening and closing at speeds exceeding 500 m/min, reducing mechanical stress and improving production efficiency.
Implementation Method 1
at least one magnetic opening device (30) which opens the clamping unit (100) without contact
Implementation Method 2
at least one magnetic closing device (31) which closes the clamping unit (100) without contact
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention relates to a clamping unit (100) for a stretching machine (10) and to a stretching machine itself. The clamping unit (100) comprises a base body (110), a gripping jaw (114), and at least one knife flap (120). The knife flap (120) is pivotably arranged on the base body (110) about a pivot axis (122) and has a complementary gripping jaw (124) at a first end (121), which, in a gripping position, interacts with the gripping jaw (114) to grip a web of material (50). The knife flap (120) also comprises a neck section (126) and a head section (128), the neck section (126) extending from the pivot axis (122) to the head section (128), which head section (128) forms a second end (123) of the knife flap (120). The head section (128) has an upper length (LK), measured in a direction of movement (R) of the clamping unit (100), which is at least 50% longer than a minimum length (LH) of the neck section (122).