Improvement of hydraulic cooling device for baler

1,AUTEFA baler overview

An AUTEFA type baler, the machine uses a combination of hydraulic system and automatic control system, the host parameters are as follows:

The designed production capacity is 10,000 tons/year (actually up to 20,000 tons/year)

Main pressure cylinder ~280/4s225, stroke 1200mm

Pre-press cylinder 125/4s100, stroke 1850mm

Synchronous cylinder ~200/~56, stroke 735.8mm

Lifting cylinder l60/4s90, stroke 1550mm

Lifting cylinder ~40, stroke 25mm

Hydraulic motor 30kW, 1470r/min

Hydraulic oil pump Axial piston pump 160YCY14-lB, nominal displacement 160mL / r, rated pressure 31.5MPa

Pre-pressed motor 22kW, 1470r/min pre-pressure oil pump Axial piston pump 63YCY14-lB, nominal displacement 63mL/r, rated pressure 31.5MPa

Set the number of measurements 7 times

Cooling motor 2.2kW, 1470r/min, cooling oil pump CB-B125 gear pump


2,failure phenomenon

As the output increases, the hydraulic system cooling device of the machine can not meet the requirements. The system temperature rises, and the temperature rise exceeds the design maximum limit (60 ° C) and reaches 65 ° C in a short time. The automatic control system automatically trips and stops, and the life of the hydraulic components is shortened. At the same time, the higher oil temperature causes the cylinder seal to fail, resulting in oil leakage. In severe cases, the forced cooling of the fuel tank by the fan still cannot solve the problem, and it is sometimes forced to stop.

3,Improvements to the cooling system of the baler hydraulic system

Through calculations, it can be concluded that the original hydraulic cooler can not meet the requirements of reducing the hydraulic system temperature to the design requirements, and the cooler must be re-selected. The heat generated by the hydraulic system mainly includes the power loss of the pump, the overflow loss of the overflow valve, and the heat generated by the pressure loss of the liquid flow through the valve and the pipeline. The heat dissipation of the pipe is basically balanced with the heat generated by the pipe and can be ignored.

Calculation of heat exchange area of the cooler

According to the formula:

F=Ps/△Tmk (5)

Where: F is the heat exchange area, and Ps is the heat dissipation power of the cooler. Calculated: Ps = 36.74 kW = 31609 keal/h. k is the heat transfer coefficient and is taken as 250 keal/m2h °C. △Tm is the average temperature difference, △Tm=[(Tl+T2)-(t2+t1)]/2, T1 is the inlet temperature of oil (65 °C), T2 is the outlet temperature of oil 40 °C, T1 is the inlet of water Temperature 18 ° C, t2 is the outlet temperature of water 21 ° C, get: △ Tm = 33 ° C

Substituting Ps, ΔT, and mk into equation (5) yields: F=31609/(33×250)=3.83m3

Refer to the cooler product sample to select the model AH1417T oil cooler with a cooling area of 4.3㎡.

The new oil cooler continuously operates at a temperature of 37 to 40 ° C, which satisfies the conditions of hydraulic temperature rise, prolongs the service life of the hydraulic components, and fundamentally eliminates the phenomenon of automatic shutdown due to temperature rise.