Metal deforming – By use of tool acting during relative rotation between tool... – During rotation of work
Reexamination Certificate
2000-03-31
2001-07-03
Larson, Lowell A. (Department: 3725)
Metal deforming
By use of tool acting during relative rotation between tool...
During rotation of work
C029S893320
Reexamination Certificate
active
06253589
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a flow-turning device and to a method for producing internally geared wheels using two sets of internal toothing arranged axially one behind the other, at least one of which is a helical toothing. By helical toothing is also to be understood a screw thread.
Internally geared wheels having sets of internal toothing that are made of steel alloys and other metallic materials are used in particular for power transmission in driven wheels of heavy goods vehicles or tractors, for example. Internally geared wheels of this type have at their forward ends sets of internal toothing that are accessible from the outside. The two sets of internal toothing can have a different diameter if the internally geared wheel is to be used in a gearbox, for example. The internally geared wheel can have a spur toothing, in which the teeth extend parallel to the axis of rotation, or a helical toothing or screw thread.
WO 96/20050 describes a method for producing internal geared portions, in which method internally geared wheels having two sets of internal toothing are produced as a result of pressure rollers flow-turning the workpiece over shaping tools. In this connection, however, only internally geared wheels having spur toothing on both sides can be produced.
SUMMARY OF THE INVENTION
The underlying object of the invention is to improve the production of internal geared portions to the extent that even portions having two sets of internal toothing, at least one of which is a helical toothing, are simple to produce.
This object is achieved in accordance with the invention by means of the features of claims
1
and
8
.
The invention proposes a flow-turning device which has a first and a second shaping tool each having an external toothing, pressure rollers for flow-turning a workpiece sitting on the shaping tools which are connected to each other, and holding means which secure the workpiece against rotation during the flow-turning of the first internal toothing on the first shaping tool. At least one of the shaping tools has a helical toothing, in which the individual teeth extend in the manner of a screw thread at an angle to the longitudinal axis of the shaping tool. There is provided at least one stripping element, which pushes the completed internally geared wheel off of the shaping tool or tools with helical toothing with relative rotation between shaping tool and internally geared wheel. During the production of the internally geared wheel, the two shaping tools are coupled to each other in a rotationally secure manner. After the production, this rotationally secure coupling is lifted, so that one shaping tool rotates together with the internally geared wheel while the internally geared wheel is detached from the other shaping tool with the aid of the stripping element. As a result of this, one-piece internally geared wheels having two sets of internal toothing, at least one of which is a helical toothing, can be produced in one operation, i.e. without having to rechuck the workpiece.
The holding means can be a movable sleeve surrounding the second shaping tool. The sleeve presses the workpiece against the first shaping tool while the first internal toothing is formed. In this connection, the sleeve holds the workpiece on the shaping tools and simultaneously secures it against rotation. After this, the sleeve is pulled back in order to be able to form the second internal toothing. The workpiece is then held firmly on the shaping tool by the first toothing.
The holding means can also be a stamped element of the first shaping tool, such as an end toothing, for example. At the start of the forming, the workpiece is pressed by the contact force of the pressure rollers on to this end toothing, so that a rotation of the workpiece is prevented without further holding means.
In a preferred embodiment of the invention, one of the shaping tools protrudes from a tool holder which is movably guided in the other shaping tool and can act upon the latter for rotational entrainment. The two shaping tools are therefore freely accessible from one side, so that the workpiece can easily be slid on to the two shaping tools and the completed internally geared wheel can easily be pushed off from the two shaping tools. Thus, it is also possible to produce internally geared wheels which have, behind a toothing, a shoulder which has a smaller diameter than the toothing, for the internally geared wheel is stripped from the shaping tools. The shaping tool does not have to be pulled out through the shoulder which has a comparatively small diameter.
In a further embodiment, the end of the second shaping tool that faces the first shaping tool has a smaller diameter than the external toothing of the second shaping tool. This renders possible a simple constructional design of the flow-turning device, for the second shaping tool is easily enclosed in an end-face bore of the first shaping tool and, after the internally geared wheel has been completed, can also easily be pulled out both from the first shaping tool and from the internally geared wheel, because the end of the shaping tool, because of its comparatively small diameter, can be moved through the internal toothing.
REFERENCES:
patent: 4884427 (1989-12-01), Sawahata et al.
patent: 296118 (1972-01-01), None
patent: 4446919 (1996-07-01), None
Putz Karl Heinz
Stein Bernd
Steinhauer Heinz
Zimmermann Wilhelm
Antonelli Terry Stout & Kraus LLP
Dynamit Nobel GmbH Explosivstoff - und Systemtechnik
Larson Lowell A.
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