Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Controlling heat transfer with molding material
Patent
1986-03-11
1989-01-17
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Controlling heat transfer with molding material
26432814, 26432816, 264 401, B29C 4578
Patent
active
047986921
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
The invention is based on a method in accordance with the type of the main claim. A regulation device for injection molding machines is disclosed in DE-OS 23 58 911, wherein the measuring evaluator pick up is disposed directly in the mold pocket surface and comes into contact with the injection molding mass. On the one hand, this results in that only a measuring of quasi-mass or the contact temperature is made possible, while an extra sensor must be installed for the tool temperature. On the other hand, such measuring value pick ups must be constructed in a very robust manner in view of the high pressures in the mold pocket and the extreme mechanical stresses which is disadvantageous in that the sensor is relatively insensitive and leaves a lot to be desired as far as its measuring accurateness is concerned, since it has a relative large time constant due to its structure which results in a lower reaction sensitivity, so that only a very slack regulation is made possible with the assistance of such measuring evaluator pick ups.
A method for regulating an injection molding machine is known from DE-AS No. 25 43 088, wherein the tool temperature is measured, however in this method it is additionally required to use a further thermosensor in a jet intermediary piece in front of the screw tyi, so as to also measure the temperature of the injection molding mass. Such a sensor is subjected to a heavy wear, above all, in fiber reinforced plastics. Furthermore, heat conductivity errors do occur which falsify the actual value of the mass temperature and in addition the expenses are relatively high.
ADVANTAGES OF THE INVENTION
In contrast thereto the method in accordance with the characterizing features of the main claim are advantageous that in addition to the tool temperature the temperature jumps resulting from the injection cycles can be registered, whereby the constancy of the mass temperature can be indirectly measured and/or in multiple pocket molds the filling of the individual molding pockets can be controlled or regulated, as will be shown in the following. Furthermore, the individual mold pockets can be controlled with respect to their complete filling, which simultaneously assures a tool safety. A measuring of the mass temperature in front of the screw tip can be eliminated and in addition the thermosensor is not subjected to a high wear because it does not come directly into contact with the mass. The reaction sensitivity is very high, since the thermosensors have only a very low mass. This high reaction sensitivity enables the measuring of the cyclically occuring temperature jumps with the required exactness.
Further advantages embodiments and improvements of the method stated in the subclaims are made possible in view of the measured stated in the subclaims. It is particularly advantageous if the minimum temperature T.sub.min and the temperature difference .DELTA.T=T.sub.max. -T.sub.min controls the maximum allowable deviation from the required quality and when exceeding this control a quality control for sorting out parts is actuated and/or the machine is switched off.
DRAWINGS
One exemplified embodiment of the invention is illustrated in the drawing and is explained in more detail in the following description.
FIG. 1 illustrates the installation of a thermosensor into an injection tool, and;
FIG. 2 illustrates in a graphic illustration the curve of the tool temperature in dependency from the time over a plurality of injection cycles
DESCRIPTION OF THE EXEMPLIFIED EMBODIMENT
FIG. 1 illustrates a part of the tool 1 with a molding pocket 2. The tool 1 is provided with a bore 3 which ends about 1 to 1.5 mm from the surface of the molding pocket 2 and whose latter part is provided with such a cross section that it centers the thermosensor 4. The relative low distance from the mold pocket surface to the thermosensor enables a good heat transmission and assures a high measuring sensitivity of the thermosensor 4. A good contact between the thermosensor 4 and the end of bore 3 is ba
REFERENCES:
patent: 4354812 (1982-10-01), Wieder et al.
patent: 4420446 (1983-12-01), Wieder et al.
patent: 4480981 (1984-11-01), Togawa et al.
Blersch Eberhard
Burr August
Hofmann Klaus
Fertig Mary Lynn
Robert & Bosch GmbH
Silbaugh Jan H.
Striker Michael J.
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