the calculations of temperature fields of the forming machines

The tables 1 and 2 shows an increase of surface temperature on the inside surface during the free forging.After removing the semiproduct there is a very rapid cooling from 103 °C to 42 °C in 5 minutes. During a break lasting26 minutes it was cooled down up to 35.8 ° C, which is comparable to the baseline temperature (32 ° C).Table 1 - Measurement results (first part)temperature/timet 1 =0 t 2 =+14 t 3 =+21 t 4 =+28 t 5 =+35 t 6 =+40 t 7 =+1.06beforestartdie forging free forging brake brakepoint 1 (°C) 32 63,7 59,6 60,7 103,2 42,1 35,8point 2 (°C) 31,8 48,6 34,1 33,8 48,9 30,3 30,1point 3 (°C) 33,8 109,1 80 79 92,3 61,6 55point 4 (°C) 32,6 36,15 35,3 34 41,67 29,5 32,7point 5 (°C) 34,7 55,4 46,47 47,7 55,67 32 31,45In the second part of measurements we recorded a significant increase in surface temperature on the inner side of thecolumn and in the middle point of the slide. There was a significant temperature difference between the pairs ofcolumns and the opposite sides of the slide, caused by different heating from long semiproduct. This difference is up to64 °C, on the column and up to 69 °C on the slide.temperature/timet 8 =+1.20 t 9 =+1.30kování(začátekt 7 =+1.17)Table 2 - Measurement results (second part)t 10 =+1.40 t 12 =+1.50 t 13 =+1.55 t 14 =+2.05free forgingt 15 =+2.12press side L L L R L R L R L R L Rpoint 1(°C) 55,3 59,5 55,2 105 49 113 68 81,5 70,8 74,5 49,2point 2(°C) 35,8 36,2 36,7 32,5 35,5 37 41 37 33 32point 3 (°C) 76 82,3 77 76,5 102 115 102,5 126 82 100point 4 (°C) 28,3 26,7 33,7 35,5 40 32,5 34,5 29,5 26,5 32point 5(°C) 34,8 36,5 35,7 104 33,9 81,5 35,4 101,5 36,5 72,5 32,5 66,1endFig.5 Comparison of surface temperatures on the left (35 °C) and the right side of the slide (104 °C)

TEMPERATURE CALCULATIONAs the next step in solving thermal problems of the forming machine was carried out FEM temperature calculation. Itsaim was to determine the surface temperature of the press CKV 84/105 for comparison with measurements. Its servedfor further calculation calibration. This knowledge can be used in future calculations for other thermal calculation onforming machine.A simplified model was created by available documentation in the program Gambit for calculation by FEM - Fluent.Boundary conditionsAmbient temperature: 30 °CThe temperature of the semiproduct 1150 °CSimplification of the calculation: modelled only a quarter of the press; semiproduct permanently attached to the lowertool; the upper part of the press is fixed in one position; air flow is not considered (only the minimum necessary for thecalculation).Fig.6 Model for FEM calculation in the FLUENTResults of calculationMaximum surface temperature on the inner side of the press column reaches 214 ° C.This is the maximum temperature, which may be on the surface structure - column - warmed to the steady-state of thethermal system.Obr.7 Results of temperature calculation – surface temperatures

The figure 8 shows the section headed by the center of the column. Warming up the column throughout the thickness ofthe inner side can be seen in the range of 195 ° C - 214 ° C. From the outside, up to about half the height of the columntemperature is the same, the temperature drops to values between 176 ° C - 195 ° C. Warming of the slide is in the samerelations.THERMAL TIME CALCULATIONFig.8 Results of temperature calculation – cross sectionThe next logical step in solving the temperature problem was the introduction time in the temperature calculation.Boundary conditions were maintained the same as for steady-state calculation: temperature 30 °C, the temperature ofthe semiproduct 1150 °C.Results of calculationThe maximum surface temperature of the column as the middle point of slide reaches 60 - 75 °C.That result (Fig. 9) represents the state of the system after 38 minutes. This result corresponds to the insertion of thesemiproduct in the second part of the measurement (Table 2).The calculation shows that about 40 minutes is too short to heat the larger structures in the existing design. Thefollowing section (Fig. 10) shows that this is only the surface temperature and calculating time period is not enough towarm this large body structure.

Fig.9 Results of thermal time calculation (38min) - surface temperatureFig.10 Results of thermal time calculation (38min) - cross section

Time temperature calculation was subsequently calculated to 100 minutes (Fig. 11). During this time period wasincreased to a maximum surface temperature to 105 °C and the construction of the press began to slowly warm.Maximum temperature of the inner part of the column reached 65 °C.CONCLUSIONFig.11 Results of thermal time calculation (100min) – cross sectionVerification of the credibility was carried out of thermal FEM calculation – in comparison with the measurement. Theresults are comparable.Calculating of temperature and temperature measurement at the press CKV 84/105 showed that in this case thermaleffect is not significant.Concept of procedure for verifying the thermal effect on forming machines:- use of stationary calculation - determination of the maximum temperature - theoretically possible- verification by the time calculation - if justifiableThis knowledge can be used in future calculations for other particular thermal calculation on forming machine. In thisparticular case, we verified that we are able to FEM analysis of thermal conditions on the forming machines.REFERENCES[1] RUDOLF, B., KOPECKÝ, M. Tvářecí stroje – Základy stavby a využití. Praha: SNTL, 1985.[2] KOVÁČ, A., RUDOLF, B. Tvárniace stroje. Btatislava: ALFA, 1989.[3] SEMIATIN, S, L. Forming and Forging. ASM Handbook, Volume 14. Ohio: Metals Park, 1996,ISBN 0-87170-020-4[4] RUDOLF, B., KOPECKÝ, M. Tvářecí stroje – Základy výpočtů a konstrukce. Praha: SNTL, 1982.