Method of making a valve seat

A method of affixing a valve seat insert into a cylinder head comprising the steps of forming a recess in said cylinder head at the base of a passage extending therethrough, forming an insert to be received in said recess and having an opening adapted to form a flow opening registering with said cylinder head passage and an outer surface positioned to engage the part of said cylinder head defining said recess, applying pressure to said cylinder head and said insert for forcing said insert into said recess, the application of pressure and the shape of said insert and said cylinder head recess being such that the size of the opening in said insert is reduced upon insertion into said recess, and passing an electrical current through the insert and the cylinder head upon pressing of the insert into the cylinder head recess for effecting resistance bonding of said insert to said cylinder head.

A method of affixing a valve seat insert into a cylinder head comprising the steps of forming a recess in said cylinder head at the base of a passage extending therethrough, forming an insert to be received in said recess and having an opening adapted to form a flow opening registering with said cylinder head passage and an outer surface positioned to engage the part of said cylinder head defining said recess, applying pressure to said cylinder head and said insert for forcing said insert into said recess, and passing an electrical current through said insert and said cylinder head during at least a portion of the time that pressure is applied for heating the cylinder head material for affixing said insert into said cylinder head recess.

A method of resistance welding an insert to a cylinder head comprising the steps of forming an insert having an opening adapted to register with a flow opening in the cylinder head, forming a recess in the cylinder head at one of end of its opening for receiving said insert, said cylinder head and said insert being formed from dissimilar materials, interposing an intermediate material between said insert in said cylinder head, simultaneously pressing said insert into said recess and passing an electric current through insert, said intermediate material and said cylinder head for effecting bonding of cylinder head, said intermediate material and said insert to each other to form a layer that varies from the material of the insert, an alloy of the insert and the intermediate layer, the intermediate layer, an alloy of the intermediate layer and the cylinder head and the cylinder head.