Lifting Bag Two-Step Vulcanization Stress Reduction
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Solution Overview
Problem
Lifting bags experience a decrease in bursting pressure with repeated filling and emptying cycles, leading to potential accidents due to internal damage from high loads and uneven material stress, as the existing manufacturing process results in non-constant material thickness and direct connection between the bladder and cover.
Innovation Solution
A lifting bag produced in two vulcanization steps, where the bladder and shell are connected only at the nipple area, with a release agent preventing full surface contact, allowing the bladder to expand more than the shell and reducing stress, and maintaining a constant material thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bladder and cover are firmly connected in a single hot vulcanizing step, then the lifting bag can be manufactured efficiently in one process step, but the material thickness becomes non-constant and internal damage occurs during repeated inflation cycles
Solution Approach 1:
The manufacturing process is divided into two separate vulcanization steps: first vulcanizing the bladder to constant thickness, then adding and vulcanizing the cover separately. This segmentation allows each component to be optimized independently, preventing the material thickness variations and internal damage that occur when both are vulcanized together in a single step.
2Stability of the object's composition
If the bladder and shell are connected over the entire surface, then the structure is more stable, but stress concentration occurs during inflation leading to reduced service life
Solution Approach 1:
The release agent is introduced to extract or prevent full surface contact between the bladder and shell during vulcanization. This allows the bladder to expand freely during inflation cycles without being constrained by excessive adhesion to the shell, thereby reducing stress concentration and extending service life while maintaining adequate structural stability through localized connection at the nipple area.
3Stability of the object's composition
If the rubber material is vulcanized before assembly, then the material properties are stabilized, but the connection between overlapping areas becomes difficult and air bubbles form
Solution Approach 1:
The bladder is vulcanized in advance as a separate preliminary step before assembly with the cover. This preliminary vulcanization stabilizes the material properties of the bladder while allowing the cover to be added and vulcanized separately in a second step, avoiding the air bubble formation problem that occurs when trying to connect pre-vulcanized materials under high pressure.
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 lifting bag maintains initial bursting pressure even after 20,000 cycles, with the bladder's extensibility being at least three times that of the shell, reducing the risk of bursting and extending service life.
Implementation Method 1
Only through the hot vulcanization process do the overlapping areas of the bladder and the parts of the cover connect to form an airtight whole
Implementation Method 2
there is a release agent between shell and bladder, the shell is not with the bladder tied together
Implementation Method 3
the bladder can expand much more easily than the shell. This is achieved in particular in that its extensibility is at least three times, at least five times as high as the extensibility of the casing
Data Source
Figure 1
Figure 2
AI summary
The bag has a rectangular bladder (20) whose interior is accessible from outside via a nipple (22) of the bladder. The nipple is located in a corner of the bladder. A shell (24) made of reinforced rubber material comprises a passage for the nipple. The shell closely encloses and is located outside the bladder. The bladder is produced in a vulcanizing step, and the shell is added after the vulcanizing step and prior to another vulcanizing step. A separating unit (26) is provided and located in a space between the shell and the bladder. The bag is made of previously web-like rubber material. An independent claim is also included for a method for producing a lifting bag from a web-like rubber material.