Wheel Hub Spline Straightness via Radial Expansion
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Solution Overview
Problem
The assembly of a driving wheel hub with a bearing ring results in deterioration of geometric precision, particularly the straightness of splines, due to shrinking during the broaching process, which is restrictive and costly in manufacturing.
Innovation Solution
A method involving radial elastoplastic expansion of the hub's upper portion before shrinking the ring, allowing for independent deformation adjustment and maintaining spline straightness through controlled expansion and subsequent machining, ensuring precise torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bearing is assembled before the splines are machined, then the manufacturing process is simpler, but the spline straightness deteriorates due to shrink-fitting deformation
Solution Approach 1:
The invention performs the broaching operation to create splines before the shrink-fitting operation to assemble the bearing. By executing the spline formation in advance on the hub alone, the process avoids the deformation that would occur if broaching were performed after shrink-fitting. This preliminary action ensures that the splines are created on a stable, undeformed workpiece, maintaining their geometric accuracy while still allowing for subsequent assembly operations.
2Manufacturing precision
If the broaching operation is performed after final assembly of the bearing, then the spline straightness is maintained, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The invention resolves this contradiction by performing the broaching operation at an optimal intermediate stage: after the hub is prepared but before the bearing is shrink-fitted onto it. This timing allows the splines to be machined on a stable workpiece (maintaining straightness) while avoiding the need for complex post-assembly broaching operations. The hub is held in a machining fixture during broaching to ensure stability, and the fixture is designed to be simple and cost-effective.
3Ease of manufacture
If the hub is shrink-fitted before broaching, then the manufacturing cost is reduced, but the spline geometric accuracy deteriorates
Solution Approach 1:
The invention establishes the correct sequence of operations: hub preparation → broaching (spline formation) → shrink-fitting (bearing assembly). By performing broaching before shrink-fitting, the splines are created on the hub while it is in its original, undeformed state, ensuring maximum geometric accuracy. The hub is secured in a simple machining fixture during broaching, keeping equipment costs low. After splines are formed, the bearing is shrink-fitted onto the hub, completing the assembly without compromising spline quality.
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
This method maintains the straightness of splines and facilitates easy assembly of the wheel hub and transmission bowl, ensuring reliable torque transmission and reducing manufacturing costs by decoupling spline formation from the assembly process.
Implementation Method 1
a step of radial elasto-plastic expansion of an upper portion of the part, which results in a flaring of both the shrink-fitting surface and a portion of the grooves
Implementation Method 2
the subsequent shrink-fitting of the ring onto the shrink-fitting surface causing a deformation of the upper portion such that said portion of the grooves approaches the reference axis
Implementation Method 3
a step of shrink-fitting the ring onto the shrink-fitting surface of the part so that a lower transverse face of the ring comes to rest against a shoulder of the part
Data Source
Figure 1~2
Figure 3~4
Figure 5~6B
AI summary
The invention relates to a method of assembling at least one ring (10) cooperating by shrink fitting with a shrink-fitting surface (110) of a part (100) defining a reference axis (X) and having a through axial cavity (120), the shrink-fitting surface (110) being rotated radially in the opposite direction of the reference axis (X), the part (100) having a free upper end (101) and an inner wall (102) extending around the reference axis (X) rotated radially towards the reference axis (X) and extending axially by delimiting at least a part of the axial cavity (120), the assembly method comprising: a step of forming, on the inner wall (102), grooves (103) extending axially; a shrink-fitting step of the ring (10) on the shrink-fitting surface (110) of the part (100) so that a lower transverse face (11) of the ring (10) comes to rest against a shoulder (105) of the part (100);the assembly process being characterized in that it comprises, subsequent to the step of forming the splines (103) and prior to the step of shrink-fitting the ring (10) onto the shrink-fitting surface (110) of the part (100), a step of radial elasto-plastic expansion of an upper portion (106) of the part (100), which results in a flaring of both the shrink-fitting surface (110) and a portion (104) of the splines (103), the subsequent shrink-fitting of the ring (10) onto the shrink-fitting surface (110) causing a deformation of the upper portion (106) such that the portion (104) of the splines (103) approaches the reference axis (X).