Television – Special applications – Manufacturing
Reexamination Certificate
1998-05-26
2001-02-06
Le, Vu (Department: 2713)
Television
Special applications
Manufacturing
C348S125000, C348S128000, C382S141000
Reexamination Certificate
active
06184924
ABSTRACT:
The invention concerns a method for the automatic detection of surface defects for continuously cast products with continuous mechanical removal of the material, which products are separated into part lengths while still in the hot state and are introduced before the final rolling in a rolling train to a material removing machine, in particular to a grinding machine, in which the material of the continuously cast product is removed generally or as a function of the defective areas determined by a defect localising equipment more or less intensively from the surface(s) to be machined, as well as a device to carry out the method.
Initial products, like slabs, ingots and billets made of steel and non-ferrous metal alloys, produced by the modern manufacturing method of continuous casting, represent the starting point for diverse high quality metal products, e.g. steel sheets or wires. In such continuous casting plants one or several endless cast strands are produced, which after passing through a cooling and bending section of a flame cutting or a shearing device travelling with it are divided into parts while still in the hot state. Following this the finished products, possibly after previous heating of the partial lengths, are produced in a rolling train. On this occasion surface defects inherent in the manufacturing technology, for example cracks, flat depressions and notches are also rolled in, thereby reducing the quality of the manufactured finished products to the extent that they become unfit for use. This applies particularly to high-grade sheets with high requirements with regard to the surface quality, so that such defects are not acceptable. Above all, it is therefore usual in the case of initial products made of high-grade materials to machine these prior to final rolling in special high-pressure grinding machines by grinding the surface. It is also known to remove surfaces by planing or milling.
A method of removal of the type mentioned in the introduction is known from EP-B-0 053 274. To achieve an improved surface quality which is advantageous for the further processing by removing the least possible material over the entire machining width, the removing process is carried out by pre-selected feeds in a reversing manner in the longitudinal and transverse direction of the slab and intensified as a function of the surface defects occurring. A defect localising equipment (detector or video equipment) is connected before the cutting tools, in particular grinding wheel, which continuously scans the surface for defect sources and carries out the removal process intensively corresponding to the defect signals. Accordingly, the cutting tools can be placed more or less against the surface of the slab or the part length.
Even though the use of a detector or of video equipment is known for the mechanical removal of material off continuously cast products, these defect localising equipment are used in practices, if at all, only for manual finishing work. The surfaces of continuously cast products are, as a rule, inspected visually by an operator of the grinding machine after a first general grinding cut, the defective areas are marked and are finish machined with the machine using manual control. This is carried out so that the surface machining is interrupted for the inspection of the initial product (slab, ingot, billet) and the initial product is transported with the aid of the working or resting table of the removal machine from a cabin enclosing it. For the purpose of inspection the operator has to leave the machine control stand which is not always in the vicinity of the removing machine. The search for defects and the evaluation, whether a follow-up machining is necessary thus depends on the qualification and the eyesight of the operator, so that a constant quality is difficult to ensure. The operator marks the defective areas manually, e.g. with a crayon, and approaches these for the finish machining with the aid of the video camera. Due to the surrounding conditions, e.g. heat, dust, etc. and the consequent poor visibility this is often a difficult and time-consuming task.
Finally, the maximum temperature of the initial product is limited by virtue of the unavoidable direct contact by the operator. This contradicts the effort of the operator, namely to carry out the removal at an as high as possible temperature, the reason for this being that the metals or metal alloys are easier to machine at higher temperatures and from the energy point of view it is not advisable to cool off the hot continuously case product, to inspect them and then carry out the surface machining and then be reheated for further processing. Accordingly, for slabs working temperatures between approx. 250 and 800° C. are strived for.
The object of the invention is to produce a method and a device to carry out the method, with which the previously mentioned disadvantages are eliminated and by means of which the economy and the quality of the surface machining can be improved, as well as the machining can be carried out in a process controlled automatically by a computer.
This objective is achieved by the method according to the invention by that the surface defect is introduced by the defect localising equipment as pictorial information to a picture processing processor and read in by a computer, comprising an integrated comparison and evaluation module and connected superposed to the machine control, in which computer the transmitted digital pictorial information is compared in a sample recognition process with stored pictures of typical surface defects and the results like length, width and area of the defect are either directly processed and stored in a coordinate-related set of defect data in accordance with a classification with regard to the relevance of the surface defects, or, after the storing in a set of surface defect data are classified in a subsequent evaluation process. There is also the alternative possibility to store the entire surface topology and show it on a display screen. In this manner an automated, computer-controlled logistic, continuous process management and follow-up as well as documentation of data relevant for the quality is achieved, and all this despite the rough surrounding conditions, e.g. heat, dust, vibrations, mechanical requirements, specific features of the surface of the workpiece and of the material as well as the type and expression of the surface defects. In this conjunction the invention is based on the recognition that conventional methods, known from non-destructive testing technology, which make use of thermal and magnetic principles or are based on ultrasonic, induction or laser technology, cannot be used due to the previously mentioned special conditions of surroundings and application.
In this conjunction the processing of the topology data transmitted by the processor to the computer in the comparison and evaluation module in a such a manner that the result can be filed directly in the coordinate-related set of defect data, has the advantage that further processing in the computer has to utilise only the considerably smaller coordinate-related set of defect data. An alternative according to the invention is to carry out the final classification in a following evaluation process based on the measuring errors read into the coordinate-related set of defect area.
In any case the filling of the topology data processed in the comparison and evaluation module immediately in the coordinate-related set of defect data offers the possibility of connecting the coordinate-related set of defect data on-line with the machine control stand, i.e. to transmit pictures of the defective positions immediately to the control stand.
A preferred execution of the invention provides that the coordinate-related set of defect data is transferred to the machine control by means of data transfer and the machine control converts this to automatic machining of the defect. Indeed, the machine-related degree of automation can be basically matched to suit the prevailing application
Braach Hans-Joachim
Schneider Volker Rainer
Brown & Wood LLP
Le Vu
Siemag Transplan GmbH
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