Plastic and nonmetallic article shaping or treating: processes – Recycling of reclaimed or purified process material – Of gaseous process material
Patent
1993-07-15
1995-07-18
Theisen, Mary Lynn
Plastic and nonmetallic article shaping or treating: processes
Recycling of reclaimed or purified process material
Of gaseous process material
264 405, 425149, 425150, B29C 4302
Patent
active
054339030
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process and apparatus for control and/or adjustment of the pressing process of a brick press for the production of formed bodies from free-flowing materials, especially refractory, ceramic materials, with a measuring and comparison device for determining setpoint value deviations of the pressing parameters, which are used to control the pressing process.
An impact press is known from DE-OS 40 09 608, in which the path of the die is measured at the end of the press path with the help of the sensor. The sensor is connected with a measuring and comparison device, in which the determined actual measurement of the thickness of the brick is compared with the desired measurement of the formed body to be pressed and is used as a signal to turn off the press. By a subsequent measuring stroke of the die, after expansion of the formed body has been completed, a second actual measurement is determined that is compared in the measuring and comparison device also with the desired measurement of the formed body. As a result, values are obtained that deviate from the desired measurement. The measurement of this deviation is used to correct the mold-filling capacity of the subsequent pressing process. In this way, the production process can be controlled with relatively low reject rates.
If the deviation from the desired measurement determined at the end of the pressing process lies outside the range of tolerance, the already completed formed body is a reject and is no longer to be used. In the course of recycling measures, it would be desirable to again feed reject formed bodies to the production process by reprocessing and to fill the crushed material in the mold. But this presents various problems. The final-pressed reject formed body is very hard and can be crushed only at a relatively high cost and expenditure of time. Another serious drawback is that additives, which are added to the mold-filling material before the pressing, become unusable or are irreversibly set by the pressing process. After working up the reject formed bodies in the case of reuse of the crushed material, these additives again have to be mixed with the mold-filling material. In addition, the additives that have become unusable are contained in the mold-filling material as impurities and contaminate the latter. The consequence of this is a reduction in quality of the finished product. In each case, the recycling of the material would be connected with an increased expense.
The object of the invention is to avoid the above-mentioned drawbacks and further to optimize the production process so that an early detection of possibly occurring defects is possible, before decisive irreversible changes in the material to be pressed have occurred.
According to the invention, this object is achieved in that the pressing power or force and the press path are measured from the beginning of the pressing process and are compared with one or more given pressure/path setpoint values or a pressure curve, and any deviations lying outside a range of tolerance are used as a signal for early ending of the pressing process.
According to another feature of the invention, the decision for early ending of the pressing process is made at a time early enough so that as yet no irreversible processes that may exert a quality-reducing influence on the end product have occurred in the material to be pressed.
To be able to determine also with this process the correct mold-filling capacity for the subsequent pressing process, the deviations from the pressure/path setpoint value lying outside and inside the range of tolerance, determined in a known way at the end of the pressing process, are used to correct the mold-filling capacity of the subsequent pressing process. In the case of early ending of the pressing process, the determined deviations from the pressure/path setpoint value are projected to the end of the pressing process and used to correct the mold-filling amount of the subsequent pressing process.
In the case of pressure molds with several cavi
REFERENCES:
patent: 4373889 (1983-02-01), Brown
patent: 4946634 (1990-08-01), Shaner
patent: 5043111 (1991-08-01), Hinzmann et al.
patent: 5211964 (1993-05-01), Prytherch et al.
Hauser Hans U.
Mick Martin
Zenner Hans J.
Jaskiewicz Edmund M.
Laeis-Bucher GmbH
Theisen Mary Lynn
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