Metal working – Scale remover or preventor – Brush type
Reexamination Certificate
1998-09-10
2001-11-27
Cuda-Rosenbaum, I (Department: 3726)
Metal working
Scale remover or preventor
Brush type
C029S081170, C029S03300H, C029S03300H
Reexamination Certificate
active
06321431
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process and a device for removing the oxide skin from the cut edges of a thin-walled, metal strip that is cut for preparing strip material for the manufacture of welded pipes.
2. The Prior Art
In the processing of thin-walled metal strips for the manufacture of welded pipes, cable sheaths and outer conductors of coaxial cables, it is a common practice to trim the edges of the strip immediately prior to the welding step. Trimming the strip allows it to be cut to the exact dimensions required for the desired pipe or tube diameter. The oxide on the cut edge is eliminated by the cutting process at the same time, so that the welding process is optimized.
The roller shears used for the trimming require a minimum width to execute the cut. Otherwise, they cannot cut properly. The width of the waste strip normally amounts to 2 to 4 mm on each edge of the metal strip. Therefore, the smaller the desired diameter of the pipe, the greater the ratio of waste to pipe material produced during trimming.
Such losses have been accepted as unavoidable in the past because manufacturers could not rely on being supplied with exactly cut strips and had to provide for exact dimension themselves. This situation has changed recently and operators of pipe welding installations can now cut the strips in their own plants so as to exactly control the quality of the cutting edge and the exact width of the strip. Furthermore, some companies advertising the most exact cutting width have gained their own market share, as they cut large amounts of strip for the manufacture of pipes, so that they were able to acquire great technical expertise. Tests with exactly pre-cut strips have shown that it is possible to weld pipes without any prior trimming. Substantial savings are achieved this way in mass production, and represent a clear competitive edge.
However, it was found in tests that the extremely exact cutting of the starting material fails to satisfy the second important precondition for a good manufacturing result if the product must be stored prior to use. Depending on the material involved, the duration of storage and the storage conditions such as temperature and humidity, an oxide skin of varying thickness develops on the surface of the cuts. This skin interferes with the welding process and may even impede it.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to develop a process for the economical removal of oxides on the surfaces of the cuts of a metal strip that has been exactly trimmed. It is another object of the invention to develop a device that carries out this process in a technically simple manner.
These and other objects are accomplished by passing the metal strip between pairs of rotating cutting tools. The tools apply a low, self-adjusting contact pressure to the cut surfaces of the strips. The surface temperature of the material being treated is maintained below 80° C. in the course of this process.
There are at least two cutting tools for carrying out this process. The tools rest against the cut surfaces of a metal strip that has been cut under low pressure. The tools are movable back and forth, reciprocating perpendicular to the plane of the cut surface. The reciprocating motion is accomplished via motors driven by compressed air or electro motors. The tools may also be pivot-mounted for swinging against the edges to be worked. The contact pressure of the cutting tools may be varied through the use of adjustable counterweights. The removed material can be removed from the metal strip via a suction device. To accomplish this, the entire device may be enclosed in a housing with a suction connection. The space within the housing is preferably filled with an inert or slightly reducing protective gas.
Steel brushes or grinding heads fitted with abrasive material can be used as cutting tools. Suitable tools for this purpose are sand papers, which are chucked across grinding heads or grinding belts. The reciprocating motion of the cutting tool prevents the narrow edges of the cut from working themselves into the cutting tools. If steel brushes are used, reversing the direction of rotation ensures that the brushes will not become blunt due to bending of the individual wires.
In the process according to the invention, from 1 &mgr;m to 100 &mgr;m of oxide deposits are removed from the cut edges.
REFERENCES:
patent: 1062248 (1913-05-01), Mueller
patent: 4575970 (1986-03-01), Kozai et al.
patent: 4827676 (1989-05-01), Kindermann
patent: 5205686 (1993-04-01), De Caussin
patent: 28 658 (1964-05-01), None
patent: 0638390A1 (1994-08-01), None
patent: 638390A1 (1994-12-01), None
patent: 800436 (1958-08-01), None
patent: 2072068 (1981-09-01), None
patent: 565994 (1944-12-01), None
patent: 6277742 (1994-10-01), None
Collard & Roe P.C.
Cuda-Rosenbaum I
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