Tyre-changing machine demounting tool with non-rolling surface
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Solution Overview
Problem
Traditional tyre-changing machines risk damaging tyres, especially run-flat tyres, during removal due to localized forces applied by hook-shaped demounting tools and rollers, leading to potential cuts and irreparable damage.
Innovation Solution
A tyre-changing machine with a support arm and demounting tool featuring a non-rolling contact surface that pushes the second tyre flank away from the rim, allowing the first flank to be extracted without rotation, distributing force over a larger surface area to reduce damage risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hook-shaped demounting tool is used to pull the tyre bead out of the rim, then the tyre removal operation can be performed, but the localized traction force may stretch and irretrievably damage the bead
Solution Approach 1:
The demounting tool is divided into a hook-shaped portion for engaging the bead and a long lever arm for applying force. This segmentation allows the force application point to be separated from the bead contact point, distributing the stress and reducing localized damage to the bead while maintaining effective removal capability
Solution Approach 2:
Instead of pulling the bead directly with the hook, the tool uses the hook to anchor and then leverages the rim itself as a fulcrum to push the bead off. This inverted approach transforms the direct traction force into a pushing motion that reduces bead stretching and damage
2Productivity
If rollers press against the tyre flank to lift the bead during rotation, then the tyre can be removed from the rim, but the great localized force on a small area increases the chances of damaging the tyre and forming cuts
Solution Approach 1:
The tool transitions from a two-dimensional roller pressing against the tyre surface to a three-dimensional lever system that uses the rim as a fulcrum. This dimensional change allows force application through a different mechanical pathway that distributes stress more evenly across the tyre structure rather than concentrating it at a single contact point
Solution Approach 2:
The long lever arm acts as an intermediary between the operator's force and the tyre bead. Instead of direct roller pressure on the tyre, the lever transmits and distributes the force through a larger area of the rim and tyre combination, reducing localized stress concentrations that cause cuts and damage
3Productivity
If the wheel rotates during the fitting and removal operations, then the demounting tool can progressively work on the tyre bead, but the combination of force application and rotation may lead to formation of cuts inside the tyre
Solution Approach 1:
The tool design incorporates a long lever arm that allows the operator to apply sufficient force to break the bead-seal connection before any rotation or movement occurs. This preliminary force application separates the bead from the rim flange in advance, eliminating the need for progressive extraction during rotation that could cause internal cuts
Data Source
Figure 1~2
Figure 3~4
AI summary
The tyre-changing machine (10) for removing a bead-broken tyre from the rim of a wheel comprises: - a bed (12) for resting on the ground; - a spindle (14) which extends from the bed (12) and on which is mountable a wheel (R) having a rim (C) and a tyre (PN) with a first flank (F1) and a second flank (F2), the spindle (14) being configured to tighten the rim (C) on it so as to fix an imaginary axis (A) of rotation of the wheel (R), with the first flank (F1) arranged in a distal position with respect to the bed (12) and the second flank (F2) arranged in a proximal position with respect to the bed (12); and - a demounting tool (32) having a non-rolling contact surface (34) able to contact and push the second flank (F2) in the direction of moving away (D2) from the bed (12) until extracting the first flank (F1) from the rim (C), the spindle (14) and the demounting tool (32) being reciprocally movable along a direction substantially parallel to the axis (A) with a stroke that extends between two ends, so as to push the tyre (PN) out of the rim (C) during the stroke.