Mixing Mills
From the smallest to the largest sizes all the mixing mills made by Harburg-Freudenberger have the following quality features:
Base plate and machine frames
Welded to withstand high loads, the machine frames are positioned on the base plate using a key and keyway arrangement and then bolted firmly into place. The machine frames and base plate are of ample proportions for the loadings they carry.
Rolls
Chilled castings with a surface hardness of 510 ± 20 HB (Brinell) and burnished roll faces provide a smooth wear-resistant surface.
Roll cooling
Standard rolls are cored, cooling water being fed into the rolls via rotary unions and cooling pipes. The water also flows back through these rotary unions, which are connected to feed and discharge lines by flexible hoses. On request, either the working roll or both rolls can be supplied with peripheral bores to ensure even more effective cooling of the compound.
Long service life is guaranteed by the use of generously sized roller bearings.
Bearing lubrication
Automatic grease lubrication is standard for the lubrication of the roller bearings.
Roll nip adjustment
The position of the rear roll can be adjusted, even under load, in a parallel or non-parallel plane by two double-acting hydraulic cylinders. A digitaldisplay in the control panel gives an exact reading of the roll nip dimensions.
The heavy-duty mixing mills from Harburg-Freudenberger can be supplied with the features illustrated, some as standard others as optional equipment. Additional optional equipment can also be quoted on request.
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Stockblender (optional), for rapid compound cooling and increased homogeneity. |
Individual roll drive through hydraulic motors and power pack. |
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Individual roll drive through bevel gearbox and thyristor controlled DC motors or frequency controlled AC motors. |
Hydraulic roll nip adjustment with pressure accumulator for rapid roll nip opening following the operation of the emergency stop. |
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Strip Cutter (optional). Mounted on a swiveling arm and applied by pneumatic cylinder, the cutter is adjustable for position on the roll and for strip width. |
Heavy-duty 750 x 2500 mm mixing mill with stockblender and individual hydraulic roll drives
Overload prevention
Pressure relief valves in the hydraulic system prevent damage to the rolls from overload or the introduction of hard foreign bodies between the rolls. In contrast to mechanical overload protection systems utilizing shear plates or bolts, no time is lost replacing damaged safety components.
Control system
The control system consists of a control cabinet and an operating panel. The control cabinet contains the power supply, main isolator switch, power distribution, PLC control system and the drive control system (for electric drives). The operating panel contains all the operating elements, push buttons, indicator lights and a graphic display showing actual values, functional status and alarm messages. The design of the control system conforms to the VDE and CE regulations and employs a safety logic model certified by the TÜV. Our PKS-JBA mixing room control system also offers a control module with order and recipe related step-by-step mill control with data acquisition.
Emergency Stop
This device, to stop the mill rolls quickly and to open the roll nip in an emergency corresponds to accident prevention regulations. Pushing the emergency stop button or actuating the body bars on the front and rear side of the mixing mill initiates the emergency braking of the roll drives and the automatic opening of the roll nip through a pressure accumulator provided on the hydraulic unit.
Drive systems
To achieve optimum compound quality in combination with high production flexibility, the heavy duty mixing mills from Harburg-Freudenberger are equipped with individual roll drives to provide infinitely variable roll speed adjustment and friction from 0.65 to 1.35.
Bevel gear drives with thyristor controlled DC motors or frequency controlled AC motors.
Individual hydraulic roll drives.
Two 550 x 1500 mm heavy-duty mixing mills with individual roll drive for variable roll speeds, hydraulic roll nip adjustment and stockblender.
| Technical Data | ||||||
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| Mixing Mill Size | 300 x 700 | 400 x 1000 | 550 x 1500 | 600 x 1800 | 660 x 2100 | 750 x 2500 |
| Roll diameter mm | 300 | 400 | 550 | 600 | 660 | 750 |
| Roll length (overall) mm | 700 | 1000 | 1500 | 1800 | 2100 | 2500 |
| Roll length (working) mm | 580 | 880 | 1380 | 1680 | 1980 | 2380 |
| Roll speed rev/min -1 | 24 | 22 | 18 | 15 | 14.5 | 12.7 |
| Peripheral speed m/min | 22.62 | 27.65 | 31.1 | 28.3 | 30 | 30 |
| Drive rating kW
(individual drive-2 motors) |
2 x 18 | 2 x 32 | 2 x 72 | 2 x 95 | 2 x 130 | 2 x 200 |
| Friction range from 0.65 to 1.35 max, infinitely variable. | ||||||
| Cooling water approx. m³/h | 6 | 8 | 14 | 18 | 20 | 22 |
| Weight approx. t | 7 | 11 | 18 | 27 | 35 | 42 |
