Patent WO2024090969A1 claims a structure in dry-electrode manufacturing equipment in which a single roll doubles as both the calendering and lamination process.
Problem Definition
The applicant is LG Energy Solution; priority date 2022-10-24, PCT filing date 2023-10-24 (application no. PCT/KR2023/016592), publication date 2024-05-02 (publication no. WO2024090969A1, original application KR20230078293A). Family applications are confirmed as EP4550431A4, US2026/0051472A1, CN119343780A, and JP2025-523246A. The legal status shown on Google Patents is “Ceased,” but this is the automatic notation that typically appears when the WO-stage application has concluded through entry into national phase in each country, and is not a legal conclusion that the right has lapsed. The mechanical contradiction is as follows: using a single roll for both calendering and lamination reduces part count, but two load-transfer paths converge on that one roll simultaneously. The question is this: which load should govern the stiffness design of the combined roll?
Kinematic Analysis
Per the claim structure, the lamination roll is arranged opposite one of the pair of rolling rolls that forms the calendering unit’s final rolling stage. In other words, this roll is the point that simultaneously receives both the electrode-sheet rolling reaction force and the current-collector bonding compression reaction force. When the two loads overlap along the same axis, there is the advantage that the load-transfer path is simplified, but if the two processes have different temperature conditions, the same roll must also absorb the resulting thermal-expansion differential. The patent document contains no specific temperature-condition figures, so this is treated as undisclosed.
Calculation and Formula Verification
Approximating the combined roll as a simple beam and assuming the two loads overlap near the center of the same span, the equivalent line load is as follows.
$$w_{eq}=w_{cal}+w_{lam}$$
Applying the same calendering calculation conditions as before (span $L=750$mm, diameter $d=300$mm, $E=210{,}000$N/mm²) and assuming the lamination reaction force is 30% of the calendering value (estimated; basis: the industry convention that bonding processes typically use lower compression force than rolling processes), $w_{eq}=40+12=52$N/mm.
$$\delta_{max}=\frac{5w_{eq}L^4}{384EI}\approx 2.56\times10^{-3}\text{mm}=2.56\mu m$$
This value is about 30% larger than the single-function roll deflection (1.97μm). In other words, the moment the two processes are combined, the design is already over the same tolerance criterion (±2μm). Dual safety-factor verification: on the strength basis, even with the increased equivalent load, the safety factor relative to yield strength remains over 200×, an over-designed region. The deflection-based safety factor, obtained by dividing the 2μm tolerance by the calculated 2.56μm, is approximately 0.78 — below 1. This means that applying this patent’s structure as-is already exceeds tolerance on the deflection criterion, and actual implementation would necessarily require re-calculating the crown-machining amount or reinforcing material stiffness.
Shop-notes
The combined-roll structure reduces part count, but that benefit is offset the moment the deflection-based safety factor drops below 1. A 2-roll separated alternative — separating the calendering roll and the lamination roll with a tension free-roll added between them — was also reviewed but not adopted. The reasons are as follows: compared with this patent’s structure, equipment length increases and an additional tension zone is created, increasing the burden of web-wandering control. The combined structure itself is reasonable in design intent, but deflection-compensation design must always be separately reflected. Machinability note: if stiffness is reinforced with a tungsten-carbide sleeve, the difference in thermal-expansion coefficient from the base material (steel) can generate residual stress during the sintering/press-fit process, so a low-temperature aging-treatment step after sleeve press-fit must be separately specified on the drawing. This analysis is an interpretation of the claim structure from the published application and does not make a determination of infringement. Applying this to an actual design requires a separate design-around review against the full claim scope.
Design-Reflection Checklist
- Combined-roll equivalent line load re-calculated
- Deflection-based safety factor of 1.0 or higher confirmed
- Tungsten-carbide sleeve residual-stress treatment process reflected
- Design-around review against patent claim scope performed
One-line summary: A combined calendering/lamination roll reduces part count, but overlapping load-transfer paths can drop the deflection-based safety factor below 1.