Hot-Formed Wheel Disk Trimming with Variable Cross-Section Bolt
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Solution Overview
Problem
Conventional steel wheels face challenges in achieving high strength and formability while maintaining lightweight construction, as increased strength reduces material formability, and introducing perforations after hot forming is costly and requires subsequent laser cutting or mechanical trimming, which is labor-intensive and wears out tools.
Innovation Solution
The method involves using trimming and application bolts with variable cross-sectional shapes during hot trimming to introduce and calibrate openings in wheel disks, allowing for simultaneous hot forming and trimming, reducing tool wear and enabling precise, high-strength wheel disks with reduced material thickness and production outlay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher strength steel materials are used, then vibration resistance and strength are improved, but the degree of formability decreases
Solution Approach 1:
The patent applies temperature parameter changes to resolve the contradiction between strength and formability. By heating the steel blank to austenitic temperatures (above Ac1) before forming, the material achieves high formability during hot forming. After forming, controlled cooling transforms the austenite into martensite, achieving high strength (1500-2000 MPa) in the final product. This temporal separation of formability (during heating) and strength (after cooling) resolves the contradiction.
2Manufacturing precision
If perforations are introduced after hot forming, then dimensional accuracy of holes is improved, but production outlay and time increase
Solution Approach 1:
The patent applies preliminary action by introducing perforations into the steel blank before hot forming, rather than after. The perforations are created when the material is still in its austenitic state, allowing easy penetration. The holes are then formed and calibrated during the hot forming process itself, achieving both high dimensional accuracy and reduced production outlay by combining multiple operations into one process step.
Solution Approach 2:
The patent merges multiple operations (perforation, hot forming, and hole calibration) into a single integrated process step. The application bolt serves dual functions: it calibrates the opening geometry while simultaneously introducing the perforation into the hot blank. This consolidation eliminates separate laser cutting or mechanical trimming steps, reducing both production time and cost while maintaining high dimensional accuracy.
3Manufacturing precision
If subsequent laser cutting is used for perforations, then hole precision is improved, but tool wear and production cost increase
Solution Approach 1:
The patent replaces subsequent mechanical trimming or laser cutting with a mechanical calibration process performed during hot forming. The application bolt with its calibrated cross-sectional shape directly forms the hole geometry through plastic deformation of the hot austenitic material. This eliminates the need for separate laser cutting operations, reducing tool wear and production cost while achieving the required hole precision through the bolt's predefined geometry.
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 approach reduces tool wear, achieves precise and strong wheel disks with lower production costs, allows for weight reduction, and integrates hot forming and trimming into a single process, minimizing the risk of cracking and requiring fewer steps, thus enhancing the efficiency and accuracy of wheel disk production.
Implementation Method 1
the blanks have to be heated to a temperature above the Ac1 temperature point, which depends on the composition of the steel. Owing to the greater forming capability of the material during the hot forming, in particular if the steel material has an austenitic structure
Implementation Method 2
the application bolt has at least one region having a cross-sectional shape which is variable in the longitudinal direction of the application bolt, and, using the application bolt, the at least one opening is calibrated via the variable cross-sectional shape
Data Source
AI summary
A method for producing a wheel disk of a vehicle wheel may involve producing the wheel disk produced from a steel blank by hot forming. The blank may be at least partially hardened, preferably press-hardened, during or after the hot forming. The blank may be hot formed using at least one punch and at least one die, and at least one opening may be introduced into the blank using hot trimming means. At least one opening may be introduced during the hot trimming using at least one trimming bolt and an application bolt, wherein the application bolt may have at least one region having a cross-sectional shape that is variable in a longitudinal direction of the application bolt. Using the application bolt, the at least one opening may be calibrated via the variable cross sectional shape.