Forging device for the production of a piston blank, and method for the production of the piston blank by means of said forging device

Patent metadata

Field	Value
Publication number	US-9782823-B2
Application number	US-201214349758-A
Country	US
Kind code	B2
Filing date	Oct 5, 2012
Priority date	Oct 7, 2011
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A forging device for producing a piston blank has a forging mold that has an essentially cylindrical cavity matching the radial outer surface of the piston blank, a forging base delimiting the cavity, and a central die consisting of a mandrel that has a conically tapering extension which is mounted on the mandrel and the shape of which matches the inner surface of the piston blank. In order to form the radially outer surfaces of the piston slipper walls and a peripheral cooling pocket located radially outside the slipper walls in the piston head, the forging device has two lateral jaws which are mounted in the forging device so as to be movable at an angle to the longitudinal axis of the forging device.

First claim

The invention claimed is:

1. A forging apparatus ( 1 ) for the production of a piston blank ( 28 ) that has a piston crown ( 29 ) and skirt elements ( 23 ) attached to the piston crown ( 29 ), which are connected with one another by way of box walls ( 27 , 27 ′), comprising:
a forging mold ( 7 , 10 , 11 ) with a cylindrical and continuous recess, corresponding to a radial outer surface of the piston blank ( 28 ),
a forging base ( 8 ) that delimits a first side of the recess, and
a center die ( 14 ) that consists of a mandrel ( 21 ) with a conically tapering extension ( 24 ) mounted on the mandrel, the shape of which extension corresponds to an inner surface of the piston blank, and which mandrel is configured to be introduced into the forging mold ( 7 , 10 , 11 ) by way of a second side of the recess, with the extension ( 24 ) leading,

wherein the forging mold ( 7 , 10 , 11 ) has two lateral jaws ( 10 , 11 ), which are mounted in the forging apparatus ( 1 ) at a slant relative to a longitudinal axis ( 3 ) of the forging apparatus ( 1 ), so that they are configured to be moved in directions that lie at a slant to the longitudinal axis of the forging apparatus, the lateral jaws being configured for molding of radially outer surfaces of the box walls ( 27 , 27 ′) and for molding of a circumferential cooling pocket ( 20 ) disposed in the piston crown ( 29 ) radially outside the box walls ( 27 , 27 ′), the cooling pocket being formed by a circumferential indentation in an underside of the piston crown, said circumferential indentation extending upward into the piston crown above a bottom of the piston crown, wherein the directions of movement of the lateral jaws enclose an angle of α≦25° with the longitudinal axis ( 3 ) of the forging apparatus ( 1 ) and run toward one another in the direction of the forging base ( 8 ).

2. The forging apparatus ( 1 ) according to claim 1 , wherein the forging mold ( 7 , 10 , 11 ) has a tubular die bushing ( 7 ) disposed on the first side of the recess, for molding of a radially outer mantle surface ( 30 ) of the piston crown ( 29 ).

3. A method for forging of a piston blank ( 28 ) that has a piston crown ( 29 ) and skirt elements ( 23 ) attached to the piston crown ( 29 ), which are connected with one another by way of box walls ( 27 , 27 ′), using a forging apparatus ( 1 ) according to claim 1 , comprising the following method steps:
introducing a heated billet ( 9 ) from which the piston blank ( 28 ) is to be forged into a cylindrical recess of the forging apparatus ( 1 ), in such a manner that the heated billet comes to lie on a forging base ( 8 ) disposed on a first side of the recess,
molding a circumferential cooling pocket ( 20 ) into the billet ( 9 ), using two lateral jaws ( 10 , 11 ), the cooling pocket comprising a circumferential indentation in an underside of the piston crown, said circumferential indentation extending upward into the piston crown above a bottom of the piston crown, the lateral jaws having inner surfaces that have a shape of radial outer surfaces of the box walls ( 27 , 27 ′), and which are mounted in the forging apparatus ( 1 ) at a slant relative to a longitudinal axis ( 3 ) of the forging apparatus ( 1 ), so that the lateral jaws are configured to be moved in directions that lie at a slant to the longitudinal axis, wherein the directions of movement enclose an angle of α≦25° with the longitudinal axis ( 3 ) of the forging apparatus ( 1 ) and run toward one another in the direction of a forging base ( 8 ), in that the lateral jaws ( 10 , 11 ) are pressed onto the billet ( 9 ),
introducing a center die ( 14 ) that consists of a mandrel ( 21 ) with a conically tapering extension ( 24 ) mounted on the mandrel, a shape of which extension corresponds to an inner surface of the piston blank, into a second side of the recess, with the extension ( 24 ) leading, wherein the extension ( 24 ) acts on the billet ( 9 ) and forms the box walls ( 27 , 27 ′) and the skirt elements ( 23 ) connected with them
extracting the center die ( 14 ) from the recess of the forging apparatus ( 1 ),
extracting the lateral jaws ( 10 , 11 ) from the forging apparatus ( 1 ) in directions opposite to the slanted directions of movement of the lateral jaws, and
ejecting the piston blank ( 28 ).

4. The method for forging of a piston blank ( 28 ) according to claim 3 , wherein the billet ( 9 ) consists of an aluminum alloy and is heated to a temperature of 480° C.

5. The method for forging of a piston blank ( 28 ) according to claim 4 , wherein the alloy AlSi12CuMgNi is chosen for the billet ( 9 ).

6. The method for forging of a piston blank ( 28 ) according to claim 4 , wherein the alloy AlSi12Cu3Ni2Mg is chosen for the billet ( 9 ).

Assignees

• Mahle Int Gmbh

Inventors

• Grunert Roland
• Friedrich Juergen
• Seng Timo
• Janisch Wolfgang
• Wenzel Armin

Classifications

• B21J13/025

  Dies with parts moving along auxiliary lateral directions · CPC title

• B21K1/18 Primary

  pistons or plungers · CPC title

• B21J5/025 Primary

  Closed die forging · CPC title

• B21J13/02

  Dies or mountings therefor · CPC title

• B21K1/185

  with cooling channels · CPC title