Pipes and tubular conduits – Combined – With end structure
Reexamination Certificate
1999-11-25
2001-06-05
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Combined
With end structure
C138S177000, C138S172000, C285S055000, C285S416000
Reexamination Certificate
active
06240966
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pipe for conveying solids provided at least at one end thereof with a circumferential radially extending coupling flange and an axially extending annular portion connected to the coupling flange, wherein an annular insert of a material having a greater resistance to wear as compared to the material of the pipe is arranged in a chamber formed by the coupling flange and the annular portion.
2. Description of the Related Art
Pipes for conveying solids, particularly concrete, are subjected to significant wear because of the abrasive effect of the conveyed medium. Because of turbulence at the radial offsets of two pipes coupled to each other, a wear which is higher than proportional occurs especially at the end at the inlet side of a pipe. The conveyed medium impinges against the end face portions of the pipe arranged downstream in the conveying direction.
Because of this increased wear, the ends of a pipe were provided with inserts of a material having a greater resistance to wear as compared to the pipe material. The purpose was to prevent premature wear of the pipe ends which could have rendered the entire pipe useless. These inserts, for example, in the form of wear rings, usually are of a non-weldable material. Therefore, it was not possible to weld the inserts to the ends of the pipes. For this reason, chambers were provided at the ends of the pipes in which the inserts were secured in their position.
DE 38 14 034 A1 discloses a curved cast pipe as a component of a pipe line for conveying solids in which inner wear inserts are provided at the ends of the cast pipe extending in radial planes of the radial flanges. The wear inserts can be pressed into corresponding recesses of the curved cast pipe or may be exchangeably mounted in these recesses. The manufacture of these recesses is comparatively simple in cast pipes because they can already be taken into consideration when the pipe is cast.
For reasons of weight, elongated pipes are usually not manufactured of cast iron, but of steel. Cylindrical steel pipes are manufactured essentially endless and are then cut to length as required for the specific application and are provided at the ends thereof with coupling flanges to be able to connect the pipes with each other. A receiving means for accommodating an insert can be provided in the coupling flanges. The coupling flanges are generally welded to the cylindrical steel pipe.
This configuration has the disadvantage that the area of the welding seam between the coupling flange and the steel pipe may become brittle which negatively influences the strength of the connection. Moreover, the coupling flanges are relatively expensive because they must be processed in a chip-producing manner for being able to meet their optimum function, i.e., an exact seat on the steel pipe and a precise positional orientation of the insert. Further costs are incurred by welding the coupling flange to the steel pipe.
As the cost for manufacturing a coupling flange and for the connection of the flange to the steel pipe increase, the costs of the individual pipe also increases. Additional cost factors are such measures as hardening the inner side of the steel pipe or constructing the steel pipe in two layers. In addition to high initial investment costs, the costs for replacement parts, for example, when a worn pipe has to be exchanged, are also high. Accordingly, there is a great potential for manufacturing such pipes more economically.
SUMMARY OF THE INVENTION
Therefore, starting from the prior art discussed above, it is the object of the present to provide a pipe for conveying solids whose ends which are particularly subjected to wear can be manufactured in a simple and inexpensive manner.
In accordance with the present invention, the coupling flange and the annular portion are formed by a chipless deformation from a tubular steel cylinder.
Accordingly, the gist of the invention is to deform in a chipless manner a tubular steel cylinder at at least one end thereof for forming a chamber for receiving an annular insert, wherein the chamber is formed by a circumferential radial coupling flange and an axially extending annular portion. This configuration results in a number of advantages.
First, apart from the chipless deformation, no additional manufacturing steps are required for manufacturing the coupling flange and the annular portion. Consequently, the pipe can be manufactured in a simple and inexpensive manner.
In addition, the coupling flange and the annular portion are manufactured in one portion from a steel cylinder. Welding seams for connecting the coupling flange to the steel cylinder are not required in the configuration according to the present invention. Consequently, dangers created by welding seams, such as, the induction of peak stresses, the brittleness in the thermal zone of influence, and the resulting strength reduction, are eliminated.
The particular advantage of the invention is the fact that the steel cylinder, the coupling flange and the annular portion are constructed in one piece. This eliminates several manufacturing steps which are required in separately manufactured coupling flanges. The pipe with integrated coupling flange and annular portion can be manufactured very simply and inexpensively by a targeted widening of the end of the steel cylinder.
In accordance with a feature of the invention, the pipe is manufactured of a relatively inexpensive steel having sufficient strength, for example, St52.
Within the scope of the invention, the steel cylinder may be elongated or also curved.
In accordance with an advantageous further development of the concept of the invention, the insert is secured in its position by a chipless deformation of at least sections of the end face of the annular portion. This provides the advantage that an axial displacement of the insert from its intended position is effectively prevented. The chipless deformation of the sections of the annular portion can be effected in the radial and/or axial directions relative to the longitudinal axis of the pipe. A deformation from the axial direction can be produced by a notch at the end face of the annular portion, wherein the displaced material forms radially inwardly directed projections.
In the case of a deformation from the radial direction relative to the longitudinal axis of the pipe, the circumferentially outer end edge of the annular portion is rounded and the material of the annular portion is at least over sections thereof displaced, for example, in the form of locking projections.
For forming the locking projections or a circumferentially extending locking ring, it may be useful to dimension the annular portion with excess material at the end face thereof, wherein the annular portion projects over the insert which rests against the rear wall of the chamber formed by the coupling flange. In the deformed state, the end face of the annular portion and the end face of the insert may coincide.
Of course, it is also within the scope of the present invention to glue the insert into the chamber.
In accordance with another advantageous feature, the insert has a smaller internal diameter than the steel cylinder. Particularly at the end of the pipe on the inlet side thereof, a reduction of the conveying cross-section by the insert results in a displacement of the critical wear zone in the conveying direction and, thus, away from the inlet end of the pipe. This effectively counteracts any premature wear in the vicinity of the coupling flange and a resulting separation of the coupling flange from the pipe.
In accordance with another embodiment, the internal diameters of the insert and of the steel cylinder are equal. The internal diameters of the insert and of the steel cylinder are preferably equal at the outlet end of the pipe. Together with the insert at the inlet end of the adjacent pipe, a wear-resistant transition area can be formed, possibly by creating a wear-resistant step, by inserts with different internal diameter
Brinson Patrick
Esser-Werke GmbH & Co. KG
Kueffner Friedrich
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