Metal founding – Process – With measuring – testing – inspecting – or condition determination
Reexamination Certificate
1998-03-20
2001-01-16
Batten, Jr., J. Reed (Department: 1722)
Metal founding
Process
With measuring, testing, inspecting, or condition determination
C164S150100, C164S151200
Reexamination Certificate
active
06173757
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of controlling quality in the production of ready-to-pour shells or core assemblies wherein a molding material is forced by means of a shooting device into an openable tool and solidified therein to form a component of a mold—core or shell—and wherein the mold component is removed when the tool is open, and thereafter handled in any desired order, transported, if need be, processed, and, if need be, completed to a mold assembly.
Basically the present invention relates to the field of foundry practice. To produce castings, foundry cores or foundry molds are generally made as separate parts, combined, and joined together to form a casting mold or core assembly. Thereafter, these core assemblies are filled with molten metal for producing, for example, a metallic workpiece. In mass production the core assemblies that are to be filled with molten metal pass one after the other through the production line.
In this connection, it is quite especially important that the workpieces cast in the core assemblies require an extremely long cooling phase, which will often last over several hours. Only after this cooling phase, is it possible to inspect the cast workpiece or product. Consequently, it is possible to find only several hours after casting and, thus, likewise several hours after the core shooting, whether or not the part cast in the core assembly is entirely free of defects.
In the event that a defective core is used, it will be possible to detect a reject resulting therefrom during the casting only hours after the production of the core. Should in this instance the defect on the core again be a systematic defect that recurs, for example, because of a defect on the tool, rejects will be produced for hours before the defect is found on the cast product. The defective cores that are accountable for these rejects may originate, as previously described, not only from defects in the tool of the core shooting machine, but also from direct damage to the cores during their handling, transportation, or assembly. In any event, it is not justifiable to be able to detect defects and, thus, rejects, only after completion of the casting operation, or during an inspection of the already cooled castings.
Moreover, damage to the mold components and/or tools may occur not only in the immediate vicinity of the shooting device, but also during any handling of the mold component and/or tool, during transportation, during a processing of the mold components, during cleaning of the tools, and in particular also during completion of the mold components to a mold assembly of any configuration.
Core and shell shooting machines of the above-described kind have been known from practice for decades. Only by way of example, reference may be made to DE 31 48 461 C1, which discloses a core and shell shooting machine.
DE 44 34 798 A1 discloses likewise a core and shell shooting machine, in which at least one visual inspection of the tool is provided. In the long run, the visual inspection disclosed in DE 44 34 798 A1 is impractical, inasmuch as the tool cannot be constantly observed, in particular within the scope of a fully automatic production. For a visual inspection, a skilled operator would have to observe the tool constantly, i.e. after each shooting operation. Even if such a visual observation or inspection were to go forward, the destiny of a core that is ejected and intended for further transportation, processing, or completing to an assembly would be left entirely open, since defects or damage may occur likewise during a manipulation or processing of the cores, during a transfer of the cores, or even during an assembly of the cores.
The same applies to the handling of the tools, in particular during a tool change, during cleaning, during transportation of the tools to a storage or during the removal of the tool from the storage or a magazine.
It is therefore the object of the present invention to provide a method of controlling the quality of ready-to-pour shells or core assemblies, which permits detection with a high probability of defects on the tool and, thus, of rejects, and which allows to prevent—systematically—repeating rejects.
SUMMARY OF THE INVENTION
The above and other objects and advantages of the present invention are achieved by a method and apparatus which includes a plurality of core shooting machines disposed along a production line, with each core shooting machine comprising an openable tool. A mold component (i.e., core) is formed at each shooting machine by a shooting device which delivers a molding material into the associated tool, and the resulting mold components are then removed from the tools and assembled to form a core assembly. The mold components and/or tools are measured in a noncontacting manner in the region of the shooting device, and/or manipulators, and/or processing stations, and/or storage areas, and/or conveying paths, that the measured data are supplied to a computer, if need be, processed therein, and compared with stored desired values, and that the mold component and/or the tool are identified as rejects or as defective when a predeterminable or definable deviation from the desired values is found.
In accordance with the invention, one has departed from the conventional production of mold components, in particular shells or core assemblies, wherein a quality control in the course of the core shooting process has been totally nonexistent. Rather, it has been common practice to exchange and clean the tool regularly, or to perform a superficial, visual inspection of the tool in use—once in a while or when need was suspected. In any event, a quality control has until now occurred neither in the actual shooting station, nor in other processing stations, and not even during the handling or transportation of the mold components, though the damage arising from rejects can be considerable in a subsequent casting of workpieces.
In accordance with the invention, it has further been recognized that during the casting process rejects can be effectively avoided, when the produced mold component is not visually inspected—as has been common practice until now—but is measured instead by applying the latest technique. Such a measuring of the produced mold component may occur after opening the tool, and/or during the removal of the mold component, and/or after the removal of the mold component, and it may be noncontacting for purposes of avoiding damage to the mold component. The data obtained from the noncontacting measurement are supplied—on line—to a computer, and—depending on needs—they are prepared or processed therein. These possibly prepared and processed data are again compared with stored desired values of the mold component. If a deviation from desired values is found outside of a predeterminable tolerance range, the measured mold component will be identified as a reject. In this respect, the computer in use for this purpose serves as a process computer, in that it influences the course of the production process to such an extent as to remove—if need be, by manipulators and automatically—the mold component that is identified as a reject. To this extent, it is effectively avoided that a mold component that has been produced or removed from the tool with defects reaches an assembly station or assembly line and constitutes there a cause for a totally defective core assembly.
In an advantageous manner, the desired values of the mold component being monitored with respect to quality and, if need be, also those of the tool, are determined on an “accepted part” with the same device as is used for carrying out the quality control. The thereby-obtained data of the measurement are processed in the computer to desired values and stored in a memory that is provided to this end. In subsequent measurements of mold components, the determined measuring data are compared with the previously stored desired values. Likewise, however, it would also be possible to input the desired values with reference to predetermined technica
Adolf Hottinger KG
Alston & Bird LLP
Batten, Jr. J. Reed
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