A simple two-roll mill for curing rubber bladders involves mixing and pre-shaping the rubber compound before the final curing (vulcanization) process. Here’s a basic setup and procedure:
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Components Needed:
1. Two-Roll Mill – Consists of two counter-rotating rolls (usually heated).
2. Rubber Compound – Uncured rubber mixed with curatives (sulfur, accelerators, etc.).
3. Release Agent (optional) – To prevent sticking (e.g., silicone spray or talc).
4. Curing Press or Autoclave – For final vulcanization.
Steps for Pre-Curing Preparation:
1. Warm Up the Mill
– Set the roll temperature between 50–70°C (122–158°F) (adjust based on rubber type).
– Ensure even heating to avoid premature curing.
2. Adjust Roll Gap
– Start with a small gap (~1–2 mm) to help incorporate additives evenly.
3. Feed the Rubber Compound
– Cut strips of uncured rubber and feed them into the rotating rolls.
– Let the rubber band around one roll for better mixing.
4. Homogenize & Sheet Out
– Pass the rubber through multiple times to ensure uniformity.
– Open the gap slightly (~3–5 mm) to sheet out the rubber for bladder molding.
5. Cut Pre-Form for Bladder
– Remove the sheet and cut it into a shape slightly larger than the bladder mold cavity.
6. Final Curing (Vulcanization)
– Transfer the pre-form into a bladder mold.
– Cure in a press/autoclave at higher temperatures (~150–180°C / 300–350°F) under pressure.
Key Considerations:
– Avoid excessive heat on the mill to prevent scorching (premature curing).
– Ensure proper dispersion of curatives before shee.jpg)
g out.
– If needed, dust with talc to prevent sticking during handling.
Alternative for Small-Scale Use:
If a two-roll mill is unavailable, some manually knead and shape the compound before curing, though uniformity may suffer.
Would you like recommendations on specific rubber formulations or curing parameters?