A method of manufacturing an iron type golf club head, including forming an iron type golf club head blank, the iron type golf club head blank having an oversized hosel portion and an oversized body portion, the iron type golf club head blank configured to accommodate a plurality of iron type golf club heads, each iron type golf club head having a unique loft angle; and removing material from said oversized body portion of said iron type golf club head blank.

A constructing-and-forging method for preparing homogenized forged pieces comprises: preparing preformed billets: cutting off a plurality of continuous casting billets, milling and smoothing surfaces of the billets to be welded, performing vacuum plasma cleaning operation to the surfaces to be welded, stacking the plurality of billets and sealing around the surfaces in a vacuum chamber by electron beam welding; forge-welding and homogenizing the preformed billets: heating the preformed billets to a certain temperature in a heating furnace and taking the heated preformed billets out of the heating furnace, forging the preformed billets by a hydraulic press, then using three-dimensional forging to disperse the welded surfaces such that composition, structure and inclusion of the interface areas are at the same level as those of the bodies of the billets. Cheap continuous casting billets are stacked and forge welded.

A constructing-and-forging method for preparing homogenized forged pieces comprises: preparing preformed billets: cutting off a plurality of continuous casting billets, milling and smoothing surfaces of the billets to be welded, performing vacuum plasma cleaning operation to the surfaces to be welded, stacking the plurality of billets and sealing around the surfaces in a vacuum chamber by electron beam welding; forge-welding and homogenizing the preformed billets: heating the preformed billets to a certain temperature in a heating furnace and taking the heated preformed billets out of the heating furnace, forging the preformed billets by a hydraulic press, then using three-dimensional forging to disperse the welded surfaces such that composition, structure and inclusion of the interface areas are at the same level as those of the bodies of the billets. Cheap continuous casting billets are stacked and forge welded.

In a forming apparatus, journal dies hold and retain rough journal portions of a preform blank therebetween, and reference crank pin die and movable crank pin dies contact rough crank pin portions thereof. In this state, the journal dies and the movable crank pin dies are moved axially toward the reference crank pin die and the reference crank pin die and the movable crank pin dies are moved perpendicular to an axial direction. With this, rough crank arm portions are axially compressed to reduce their thickness to that of crank arms of a forged crankshaft, and the rough crank pin portions are pressed perpendicular to the axial direction to increase an amount of eccentricity to that of the forged crankshaft crank pins. Consequently, it is possible to form a blank for finish forging having a shape generally in agreement with a shape of the forged crankshaft for a three-cylinder engine.

In a forming apparatus, journal dies hold and retain rough journal portions of a preform blank therebetween, and reference crank pin die and movable crank pin dies contact rough crank pin portions thereof. In this state, the journal dies and the movable crank pin dies are moved axially toward the reference crank pin die and the reference crank pin die and the movable crank pin dies are moved perpendicular to an axial direction. With this, rough crank arm portions are axially compressed to reduce their thickness to that of crank arms of a forged crankshaft, and the rough crank pin portions are pressed perpendicular to the axial direction to increase an amount of eccentricity to that of the forged crankshaft crank pins. Consequently, it is possible to form a blank for finish forging having a shape generally in agreement with a shape of the forged crankshaft for a three-cylinder engine.

In a forming apparatus, stationary journal dies (10U, 10B) and movable journal dies (11U, 11B) each hold and retain rough journal portions (Ja) of a preform blank (4) therebetween, and crank pin dies (12) contacts rough crank pin portions (Pa) thereof, and in this state, the movable journal dies (11U, 11B) are moved axially toward the stationary journal dies (10U, 10B) and the crank pin dies (12) are moved in the same axial direction and in an eccentric direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the eccentric direction to increase the amount of eccentricity to that of the crank pins of the forged crankshaft.

In a forming apparatus, stationary journal dies (10U, 10B) and movable journal dies (11U, 11B) each hold and retain rough journal portions (Ja) of a preform blank (4) therebetween, and crank pin dies (12) contacts rough crank pin portions (Pa) thereof, and in this state, the movable journal dies (11U, 11B) are moved axially toward the stationary journal dies (10U, 10B) and the crank pin dies (12) are moved in the same axial direction and in an eccentric direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the eccentric direction to increase the amount of eccentricity to that of the crank pins of the forged crankshaft.

In a forming apparatus, movable journal dies (10U, 10B) and stationary journal dies (9U, 9B) retain rough journal portions (Ja) of a preform blank (4) therebetween, and reference crank pin die (11) and movable crank pin dies (12) contact rough crank pin portions (Pa) thereof, and in this state, the movable journal dies (10U, 10B) and the movable crank pin dies (12) are moved axially toward the reference crank pin die (11) and the reference crank pin die (11) and the movable crank pin dies (12) are moved in a direction perpendicular to an axial direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the direction perpendicular to the axial direction to increase an amount of eccentricity to that of the crank pins of the forged crankshaft.

In a forming apparatus, movable journal dies (10U, 10B) and stationary journal dies (9U, 9B) retain rough journal portions (Ja) of a preform blank (4) therebetween, and reference crank pin die (11) and movable crank pin dies (12) contact rough crank pin portions (Pa) thereof, and in this state, the movable journal dies (10U, 10B) and the movable crank pin dies (12) are moved axially toward the reference crank pin die (11) and the reference crank pin die (11) and the movable crank pin dies (12) are moved in a direction perpendicular to an axial direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the direction perpendicular to the axial direction to increase an amount of eccentricity to that of the crank pins of the forged crankshaft.

A method for assembling an insert with a recess of a structure, using a propulsion tool guiding a striker slide pushing a striker, and including a distributor device for controlling the forwards or backwards motion of the striker slide, and a tube guiding the striker and including a head with an internal profile adapted to the insert to be produced, a bar of material is inserted into the tube and heated to a predetermined temperature, a propulsion fluid is injected and a distributor slide is operated to move the striker slide at a predefined speed and to drive the striker to strike the preheated bar, force it into the recess and deform it so that it occupies the volume of the internal profile of the head.