Apparatus for manufacturing a formed body having a concentric hub

Abstract

An apparatus for manufacturing a formed body having a concentric hub. The concentric hub is formed from a round blank, with a rotating tool plate on which the round blank lies, a work roller and a follower roller capable of being infed axially and/or radially for shaping of the hub about a concentrically arranged mandrel. The work roller has a pressure surface on its side facing toward the mandrel, against which pressure surface material of the round blank is removed in flow-forming abuts. The pressure surface is inclined outwardly relative to the central axis of the mandrel.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to an apparatus for manufacturing a formed body having a concentric hub from a round blank, with a rotating tool plate on which the round blank lies.

[0003] 2. Description of Prior Art

[0004] Formed bodies manufactured with such apparatus find use in many application areas. The chipless manufacturing method known as flow-forming is usually a cold deformation method and is distinguished by a variety of advantages permitting, in particular, rational and economical manufacturing for mass-produced articles such as are used for example as transmission parts in automobile making.

[0005] An apparatus of the stated type is known for example from WO 94/20235. There a formed body provided with a concentric hub is manufactured by flow-forming from a round metal blank, that is, a sheet-metal plate having a central hole.

[0006] With the aid of the work roller, material from the round blank is squeezed out by radial infeeding and displaced in the direction of the mandrel, where it is shaped into a hub by shaping against the mandrel. In the course of material displacement, which can also be called flow, the thickness of the round blank is reduced in accordance with the material removal necessary for hub shaping.

[0007] While the work roller effects on the one hand the removal of material from the round blank and on the other hand the movement of the material in the direction of the mandrel, the follower roller serves first to prevent flexing of the round blank during flow-forming and second to perform an exact shaping against the mandrel. The follower roller follows the work roller at a close interval.

[0008] In the known apparatus the work rollers are fashioned such that their circumferential pressure surface lies parallel to the central longitudinal axis of the mandrel or of the round blank, the pressure surface directly adjoining the flow-forming edge, which can be brought into engagement with the round blank.

[0009] In the axial and radial infeed of the work roller, the material separated from the round blank builds up in front of the pressure surface and is displaced into the region of the mandrel, where it flows along the mandrel until it reaches a stop that controls the height of the hub.

[0010] In the stated material buildup, however, very large forces arise at the pressure surface, which forces act on the work roller and not only necessitate corresponding sizing of the corresponding mechanical components but also lead to relatively high wear.

[0011] It has been found that the upset material does not flow parallel or nearly parallel to the mandrel until immediately before coming to abut against the mandrel, while before this time it takes on the space of a relatively thick bulge.

SUMMARY OF THE INVENTION

[0012] It is therefore a goal of the invention to fashion an apparatus of the stated type so that the loads occurring during flow-forming are reduced.

[0013] This goal is achieved by an apparatus that has the features of claim 1 and/or a method according to claim 10.

[0014] It has surprisingly been found that a substantially smaller bulge-like material buildup is thus attained in the radial infeed of the work roller. Instead, the material separated from the round blank by the work roller flows along the pressure surface at an early time, so that a much smaller loading or a reduction in the force that must be expended for flow-forming results in a natural way. This is as much as 40% less than in flow-forming according to the prior art, given an optimized design of the work roller, which in an advantageous development of the invention provides an inclination of <10°, preferably 3-5°.

[0015] The hub so far preshaped is not indeed pressed directly against the mandrel by the work roller. This is effected by the follower roller, whose pressure surface lies parallel to the central longitudinal axis and with which the hub, previously slightly oblique or takes on a somewhat funnel-like shape, presses against the mandrel in such a way that a cylindrical shape comes about.

[0016] According to a further idea of the invention, the follower roller has a projection for the end limitation of the hub, against which projection the hub abuts with its free end face during shaping.

[0017] The mandrel here can likewise have a stop in the shape of a shoulder that limits the height of the hub and lies in the same plane, parallel to the round blank, as the projection of the pressure roller.

[0018] It is also conceivable, however, to fashion the mandrel with a smooth shank throughout, so that here only the follower roller forms the end limitation of hub shaping.

[0019] In order to optimize production, it is further provided to leave between the stop-forming projection of the follower roller and the mandrel a small annular gap into which excess material can pass during hub shaping, which excess material is removed in subsequent hub machining.

[0020] The width of the projection and of the shoulder are preferably equally large but together equal to at most the wall thickness of the hub.

[0021] In a method for chipless manufacturing of the hubbed formed body from a round blank according to the preamble of claim 10, the hub is initially shaped by the work roller in a funnel shape with its wall positioned obliquely outwardly relative to the central axis of the mandrel and is afterward brought to a cylindrical shape by pressing of the wall against the mandrel by the follower roller.

[0022] Further advantageous developments of the invention are characterized in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In what follows, an exemplary embodiment of the invention is described on the basis of the appended drawings.

[0024] The single figure shows a partial section through an apparatus according to the invention in a schematic longitudinal section.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The figure depicts an apparatus for manufacturing a formed body 1 having a concentric hub 12, which apparatus has a rotating tool plate 2 in the shape of a chuck, a work roller 4, a follower roller 7, and a mandrel 3.

[0026] Tool plate 2 has a recess in which there lies a round blank 11 onto which hub 12 can be shaped by work roller 4 and follower roller 7, to which end work roller 4 can be infed axially and radially relative to the central axis of round blank 11.

[0027] For shaping, initially disk-shaped round blank 11 with a central hole is laid into tool plate 2 and set in rotation. Material of round blank 11 that initially protrudes above tool plate 2 is squeezed in the direction of mandrel 3 by a pressure edge of work roller 4, the material so separated being supported against a pressure surface 6 of work roller 4.

[0028] Starting from round blank 11, this pressure surface is inclined outwardly relative to the longitudinal axis of mandrel 3 so that an initially roughly funnel-shaped hub is fashioned, as illustrated at the right in the figure.

[0029] The inclination angle &agr; of pressure surface 6 is preferably 3-5°.

[0030] Follower roller 7 follows immediately behind work roller 4, being supported against the correspondingly formed surface of round blank 11. Follower roller 7 also has a pressure surface 13, which, however, lies parallel to the central axis of mandrel 3. Initially inclined hub 12 is pressed against mandrel 3 by this pressure surface and comes into abutment there so that a concentric cylindrical shape of hub 12 is generated.

[0031] On its side facing away from round blank 11, follower roller 7 has a projection 8 that represents an end limitation in the fashioning of hub 12 and governs its height dimension.

[0032] In this sense, mandrel 3 has a circumferential shoulder 9, which likewise forms a stop against which hub 12 abuts. The respective stop surfaces of shoulder 9 and projection 8 lie in one plane.

[0033] As can further be seen, an annular gap 10 is formed between projection 8 and mandrel 3, into which gap excess material can flow during hub shaping, so that an otherwise exact fashioning of hub 12 is possible without any problem. This excess can subsequently be removed by machining.

Claims

1. An apparatus for manufacturing a formed body having a concentric hub from a round blank, with a rotating tool plate on which the round blank lies, a work roller and a follower roller capable of being infed axially and/or radially for shaping of the hub about a concentrically arranged mandrel, the work roller having a pressure surface on its side facing toward the mandrel, against which pressure surface material of the round blank removed in flow-forming abuts, characterized in that the pressure surface is inclined outwardly relative to the central axis of the mandrel, specifically starting from the round blank.

2. Apparatus according to claim 1, characterized in that the inclination of the pressure surface is <10° relative to the longitudinal axis of the mandrel.

3. Apparatus according to claim 2, characterized in that the inclination of the pressure surface is 3-5°.

4. Apparatus according to claim 1, characterized in that the follower roller has a projection against which the hub abuts in final position.

5. Apparatus according to claim 1, characterized in that the mandrel has a circumferential shoulder to limit the height of the hub.

6. Apparatus according to claim 4, characterized in that the shoulder and the projection lie in one plane.

7. Apparatus according to claim 6, characterized in that the width of the shoulder and the width of the projection are equally large.

8. The apparatus according to claim 1, characterized in that the width of the shoulder and of the projection together are equal to or less than the thickness of the wall of the hub.

9. Apparatus according to claim 3, characterized in that an annular gap is formed between the projection and the mandrel in final shaping position of the follower roller.

10. A method for chipless manufacturing of a formed body having a hub from a round blank in which the round blank in rotating with respect to at least one work roller is reduced in thickness radially and/or axially from the outside inwardly by pressing with the work roller and the material removed is shaped about a centrically arranged cylindrical mandrel to make the hub, characterized in that the hub is initially shaped by the work roller in a funnel shape with its wall positioned obliquely outwardly relative to the central axis of the mandrel and is afterward brought to a cylindrical shape by pressing of the wall against the mandrel by a follower roller.