Method for producing a housing for a throttle valve connection piece

A method for producing a housing (12) for a throttle valve (10), which housing (12) has a throttle orifice (16) for a throttle valve (20), the housing (12) being produced from plastic (14) by an injection molding method, and, during the injection molding method, plastic (14) being partially injected around a metal cylinder (28) which, at least in a region of the throttle valve (20), forms the throttle orifice (16), wherein, before the injection molding method, an expanding mandrel (50) is expanded against an inner face (33) of the metal cylinder (28), during the injection molding method the inner face (33) of the metal cylinder (28) is supported at least partially by the expanding mandrel (50), and, after the injection molding method, an outer circumference (80) of the expanding mandrel (50) is reduced to remove the expanding mandrel (50) from an interior (70) of the metal cylinder (28),

• wherein the expanding mandrel (50) has an expanding device (58) and an outer casing (54) at least partially surrounding an expanding device (58), before the injection molding method the outer casing (54) of the expanding mandrel (50) being expanded radially against the inner face (33) of the metal cylinder (28) by the expanding device (58), during the injection molding method the outer casing (54) of the expanding mandrel (50) being expanded radially against the inner face (33) of the metal cylinder (28) by the expanding device (58), and, after the injection molding method, radial contraction of the outer casing (54) of the expanding mandrel (50) being carried out by the expanding device (58) to remove the expanding mandrel (50) from the interior (70) of the metal cylinder (28),
• wherein the expanding device (58) has an axle (60), a securing means (66) and a supporting body (64), the supporting body (64) being movable along the axle (60), having an approximately rotationally symmetric shape, tapering along the axle (60) and having a first end region (72) with a smaller diameter and a second end region (74) with a larger diameter relative to the first end region (72), before the injection molding method, in order to expand the outer casing (54) of the expanding mandrel (50) against the inner face (33) of the metal cylinder (28), the supporting body (64) being moved, with the first end region (72) of the supporting body (64) having a smaller diameter, along the axle (60) into the interior (70) of the metal cylinder (28), during the injection molding method the supporting body (64) being fixed on the axle (60) by the securing means (66), and, after the injection molding method, in order to remove the expanding mandrel (50) from the interior (70) of the metal cylinder (28), a contraction of the outer casing (54) of the expanding mandrel (50) being carried out by means of a movement of the supporting body (64) along the axle (60) out of the interior (70) of the metal cylinder (28).