초록 ▼

A method and apparatus for cold working a metallic blank having a central hole into a substantially annular or cylindrical article such as an internally and or externally toothed gear, with the method including forcibly inserting a hollow metallic blank at a normal temperature into a die cavity form

A method and apparatus for cold working a metallic blank having a central hole into a substantially annular or cylindrical article such as an internally and or externally toothed gear, with the method including forcibly inserting a hollow metallic blank at a normal temperature into a die cavity formed between a mandrel placed on a fixed base and a die concentrically surrounding the mandrel so that the blank is plastically deformed between the mandrel and the die; forcibly inserting a subsequent hollow metallic blank into the die cavity while the relative position between the mandrel, the die and the first blank being plastically deformed therebetween is kept unchanged; and urging the subsequent blank against the first blank to extrude the first blank forwardly out of the die whereby the first-said blank is formed into a tubular article.

대표청구항 ▼

An apparatus for cold working hollow metallic blanks into hollow articles, each blank having a central through-hole, the apparatus comprising: means for defining therein an open-topped and open-bottomed space for receiving the blanks successively and forming an outer periphery of each blank, said sp

An apparatus for cold working hollow metallic blanks into hollow articles, each blank having a central through-hole, the apparatus comprising: means for defining therein an open-topped and open-bottomed space for receiving the blanks successively and forming an outer periphery of each blank, said space defining means being movable upwardly and downwardly between a lower position and a raised and floating position; means for guiding the upward and downward movements of said space defining means and for biasing the same toward said raised and floating position; inner means disposed in said space coaxially therewith for forming the inner peripheral surface of each blank, said inner means cooperating with said space defining means to define therebetween an open-topped and open-bottomed forming space, said inner means being movable in an upward and downward direction between a lowered position and a raised position; urging means disposed above said forming space and being movable in upward and downward directions; means for drivingly moving said urging means downwardly to urge the blanks into said forming space successively so that each blank is plastically worked and extruded into a hollow article; and means for stopping the downward movements of said space defining means and said inner means at their lowered positions, respectively; wherein when said urging means is downwardly moved by said moving means to force a blank into said forming space, said sapce defining means and said inner means are moved downwardly to their lowered positions against the force of said guiding and biasing means, such that said urging means is further moved downwardly by said moving means with said space defining means and said inner means both maintained stationary at their lowered positions to forcibly move said blank in said forming space relative to said space defining means and to said inner means whereby said blank is shaped in said forming space into a preform; and wherein said urging means is then moved upwardly by said moving means to permit said space defining means to be moved by said guiding and biasing means to said raised and floating position, the upward movement of said space defining means being transmitted to said inner means by the preform held therebetween whereby said inner means is also raised together with said space defining means by said guiding and biasing means, said urging means being again downwardly moved by said moving means to urge a succeeding blank into said forming space whereby said preform is extruded out of said forming space by said succeeding blank to form a hollow article.