2 Materials and Methods
2.1 Analysis of Tool Temperature Changes During the Forging Process
3 Analysis of Selected Methods of Tool Heating: Discussion of Results
3.1 Warmup by Waste Material
3.2 Heating with Patron Heaters Placed in the Tool Housing
For the assumed coefficient 2000 W/m 2 K, the temperature of the insert stabilizes after about 60 minutes and reaches the maximal value of about 50 °C for the external area of the die. The working pattern temperature is lower.
For the assumed coefficient 10,000 W/m 2 K, the die temperature stabilizes after about 40 minutes and reaches the maximal value (directly by the heater) of even 130 °C. The working pattern temperature is already much lower and does not reach > 70 °C.
Unfortunately, one can suppose that, for the proposed system, the coefficient with the value of 2000 W/m 2 K would be appropriate, as the insert is not in direct contact with the heater; therefore, nearly all the heat is released into the housing.
Also problematic is the fact that heating the housing will cause the latter to expand, which may have a negative effect on the mounting of the insert and may also reduce the contact of the housing with the tools, thus reducing the heat conduction to the tools.
3.3 Heating with Patron Heaters Placed in a Forge Heating Element
3.4 Induction Heating
3.5 Summary and Conclusions
The proposed procedure of charge material heating enables effective preheating of forging tools, without the risk of overheating or underheating, within the time of about 50 minutes by implementing three heating cycles.
The innovative method of using a heater introduced into the housing does not yield sufficient results, as more heat is released into the rest of the tooling than into the die. Also, heating of the housings may cause their expansion and the formation of clearances between the die and its housing, which is disadvantageous in relation to the instrumentation’s construction.
Preheating using a heater in the shape of a forging provides satisfactory results (heating time about 35 minutes) and provides a new alternative heating method, which is more energy efficient owing to the matching of the heater’s shape to that of the forging die.
Induction heating is the fastest and most effective heating method, which makes it possible to reach the desired temperature already after 15 to 20 minutes of heating. It can also be successfully applied for additional heating during maintenance shutdowns or breakdowns in short heating cycles of 5 to 10 minutes.