Patent ID: 7673785

Claim:
A method for making cutting pick formed of a cutting tip of one material which is fixed to a pick body of another material, the pick body including a generally cylindrical cavity for receipt of a generally cylindrical anchor portion of the tip, the tip including a coating bonded to the cylindrical outer surface of the anchor portion, the internal diameter of the cavity being greater than the external diameter of the coated anchor portion to leave an annulus between the cylindrical outer surface of the coated anchor portion and the facing wall of the cavity when the anchor portion is received within the cavity, the pick body being of a metal material having a greater coefficient of thermal expansion than the material of the cutting tip, the method comprising the steps of, in any order: (i) inserting the coated anchor portion into the cavity; (ii) heating the tip, and the portion of the pick body defining the cavity; (iii) introducing molten metal into the cavity, the metal being one which is selected to bond to each of the coating applied to the anchor portion and the cavity wall upon solidification of the metal, and thereafter comprising: (iv) cooling the tip and the pick body defining the cavity, so that: (a) the molten metal solidifies; and (b) the pick body portion defining the cavity contracts exerting sufficient pressure on the solidified metal to press the metal against the surface of the anchor portion to fix the tip to the pick body.