Abstract: A seal for rock bits having a Belleville type spring and a lock-ring embedded in rubber is made in a process where the spring and the lock-ring are plasma etched before the metal parts are embedded in a partially cured rubber composition. The rubber is cured in a mold to provide a seal having significantly strengthened rubber-to-metal bonding. Preferably, highly saturated nitrile rubber is used for the seal, and the rubber composition preferably also includes lubricating agents which reduce friction between the rubber seal and rotating metal parts of the rock bits.

Abstract: A seal assembly particularly adapted for sealing rock bit bearings is disclosed. The seal comprises an O-ring made of a resilient material which swells substantially when effectively exposed to a lubricant used for lubricating the bearing. The O-ring seal is mounted into the rock bit in a relatively low state of compression or squeeze between the surfaces to be sealed. During operation of the bit, the O-ring seal swells due to exposure to the lubricant, and consequently compression or squeeze of the seal increases substantially. The novel seal assembly compensates for undesirable compression set and wear of the O-ring.