Forged 9Cr3Mo Cold Rolling Back-Up Roll For Copper Foil Rolling Mill

Product Advantage

1. High hardness and ultimate wear resistance (long lifespan)

Hardness: Overall HRC 55~60; Surface induction hardening can reach HRC 65~68

Wear resistance: High carbon and high chromium form a large amount of M-type high hardness carbides (hardness~1800 HV)

Copper foil scene value:

• Copper foil rolling has high pressure, high speed, and long stroke, and the wear of supporting rollers directly affects the accuracy of plate shape and thickness

• The wear resistance of 9Cr3Mo far exceeds that of 9Cr2Mo, 40Cr, and GCr15, with a 30% increase in lifespan+

• Reduce the frequency of roller replacement, increase the start-up rate, and lower costs

2. Good hardenability, deep hardened layer, and uniform hardness (stable accuracy)

Hardened layer depth: 18-22 mm (radial direction)

Advantage:

• The large diameter support roller has uniform hardness and no soft spots throughout the entire cross-section

• After grinding, the surface core hardness gradient is gentle, and the long-term use accuracy is stable

Copper foil value:

• Copper foil (especially ultra-thin copper foil ≤ 12 μ m) is extremely sensitive to roller surface runout, cylindricity, and hardness uniformity

• Uniform hardness → Uniform rolling pressure → Good plate shape, small thickness difference, no waves/edge waves

3. High strength, high toughness, and strong accident resistance (safe and reliable)

High compressive strength: The support roller can withstand rolling forces of tens of thousands of tons and alternating bending/shear stresses

The role of Mo element: refining grains, improving tempering stability, and enhancing high-temperature strength

Resilience: Good toughness of the heart, not easily broken, resistant to peeling, and resistant to thermal shock

Copper foil value:

• Avoid malignant accidents such as broken rollers, peeling, and falling pieces (once they occur, it will scratch the entire copper foil and cause huge losses)

• Allow short-term overload, steel jamming, and belt breakage impact, with high equipment safety

4. Good thermal stability, heat-resistant friction (small temperature rise, no deformation)

Mo element: maintains over 80% strength at 600 ℃, does not soften or collapse at high temperatures

Copper foil scene:

• Friction heating during high-speed rolling, with roll surface temperature reaching 200~300 ℃

• 9Cr3Mo has good thermal stability → the roller surface does not stick to copper, does not oxidize, does not deform, and has stable roughness

5. Surface quality and accuracy retention (copper foil surface without defects)

Forging+precision grinding:

• Surface roughness Ra ≤ 0.02 μ m

• Radial runout ≤ 1 μ m, cylindricity ≤ 1 μ m

Copper foil value:

• The accuracy of the support roller directly determines the deflection of the work roller → uniformity of copper foil thickness

• Smooth roller surface, no pitting, no scratches → The copper foil surface is shiny, without indentation, bright spots, and pinholes

• Meet the ultra clean surface requirements of lithium battery copper foil and PCB electronic copper foil

6. Corrosion resistance (resistance to copper/emulsion corrosion)

High Cr (~3%): A dense passivation film is formed on the surface

Copper foil rolling: in contact with emulsion, copper powder, and trace corrosive media

Advantages: Not easy to rust, not easy to pitting, long-term smooth roller surface, not polluting copper foil

Technical Parameters

1. Standard Chemical Composition (Mass Fraction%)

2. Special Technical Requirements For Copper Foil Rolling Mill

(1) Forging and billets

• Forging ratio ≥ 3:1, multi-directional forging, dense structure.

• Using ESR steel billets with high purity, no inclusions or segregation.

(2) Hardness and Hardened Layer

• Roll body hardness: 70~75 HS (≈ HRC 63~66), with a hardness difference of<3 HS for the same roll.

• Hardened layer depth: ≥ 15-25mm (much higher than ordinary rolling mills).

• Roll neck hardness: 45~50 HS, balancing strength and toughness.

(3) Precision index (precision copper foil rolling mill)

• Radial runout (circular runout): ≤ 0.001 mm (1 μ m).

• Cylindricity/straightness: ≤ 0.001~0.002 mm.

• Surface roughness: Ra ≤ 0.02~0.05 μ m (mirror level, anti copper foil scratch).

• Outer diameter difference: ≤ 0.05 mm.

(4) Heat treatment process

• Quenching and tempering: quenching+high-temperature tempering to obtain a strong and tough matrix.

• Final: Induction hardening+low-temperature tempering (150-180 ° C), or cryogenic treatment to stabilize the structure.

3. Manufacturing And Surface Treatment Process

• Cutting → forging → rough machining → quenching and tempering heat treatment

• Semi precision grinding → (cryogenic treatment) → induction hardening/surface hardening

• Fine grinding/ultra fine grinding → Non destructive testing (UT/MT) → Dynamic balancing

• Surface treatment: hard chrome plating (≥ 0.15 mm) or polishing

Product Uses

1. Copper foil cold rolling/single stand precision rolling unit (final critical stand)

• Core function: As a supporting roller, it directly supports the working roller, withstands rolling pressure of hundreds to thousands of tons, suppresses the bending deformation of the working roller, and ensures the accuracy of copper foil plate shape, thickness uniformity, and surface smoothness.

• Rolling conditions: room temperature cold rolling, high rolling force, high rolling speed, strong emulsion/pure water cooling, continuous high load production.

• Product specifications: Mainly producing 6-12 μ m lithium battery copper foil, 12-105 μ m standard electrolytic copper foil, and rolled copper foil.

2. Copper foil leveling/slitting unit

Used for secondary finishing, eliminating internal stress in copper foil, improving flatness, surface glossiness, and dimensional accuracy.

3. High precision rolled copper foil rolling mill

Suitable for the production of high ductility and high conductivity flexible copper-clad laminate (FCCL) copper foil using the rolling method.