Straightener Concepts
Straightening machine
The machine is assembled on a solid, welded machine stand whose virtue lies in the fact that is virtually vibration- and resonance-free, and also highly resistant to twisting. Inside the basic unit are the drive motor and lubrication unit, which are mounted directly on the base plate and are easily accessible through maintenance ports.
A central oil collection vessel is located on the upper side of the machine stand, and its volume is sufficient to hold the entire volume of oil from the lubricating unit in the event of an emergency. This ensures that no oil will spill onto the workshop floor.
Straightening rollers
The straightening rollers are hardened, tempered and have a strength rating of 900 – 1300 N/mm2, which results in a surface hardness of 60-64 HRC. The material used is a case-hardened steel, which determines the strength depending on the diameter.
The surface is ground to a roughness of no more than 4 mm. The needle bearing is located outside the straightening area, and is protected by sealing rings. The straightening rollers rest on support rollers, which prevent the rollers from bending. The drive is applied separately via universal-joint shafts from the distributing gears. All the rollers are driven.
Gears
The gears are single-speed, distributing the drive force equally to all straightening rollers. All the toothed wheels are case-hardened and ground on every surface. They too, run on needle bearings. The gear assembly is oil-filled and not connected to the oil circulation system.
Universal-joint shafts
The universal-joint shafts essentially consist of 2 heavy-load-bearing ball joints which are equipped with a device to compensate for elongation. The universal-joint shafts are equipped in the factory with a quick-change assembly, enabling them to be changed without undoing any screws or pins. The universal-joint shafts are provided with automatic lubrication from an oil circulation system. Support rollers and straightening roller bearings are always lubricated with grease.
Drive
Drive is provided by a maintenance-free rotary motor, which is driven by a frequency inverter. Transmission from the motor to the gears is effected via a v-belt, which at the same time serves as an attenuator and prevents excessively hard forces being transmitted to the gears.
Overload protection
A torque-dependent overload protection device protects the machine from excessive stress. This device is set up in the factory, and in the event of the machine being overloaded, an indication will be shown directly on the operator station screen. The drive will stop instantly, the only function available after the overload is “Inch in reverse”.
Central lubrication unit
The central lubrication unit is in the form of a compact module. The oil flowing back from the lubrication points (universal-joint shafts) is cleaned by a return-line filter. Monitoring of the lubrication process is performed on both the outflow and the return flow. The lubricant vessel includes an oil-level monitor, and there is a pressure switch in the outflow pipe. In the event that the lubrication system fails, the machine stops instantly and indicates the problem on the operator station screen.
Manual adjustment roller frame
The machine is adjusted by means of two hand wheels located in the front.
The measurement of the adjustment is carried out by a dial gauge associated to each hand wheel. The accuracy of reading is 0,01 mm.
Option – Motorised adjustment device for roller block with digital display
The entire upper roller block is set by means of 2 spur-geared motors, which adjust the heights of the machine’s infeed and outfeed respectively. The strength of the material to be levelled is normally set on the outfeed side. On the infeed side a delivery is normally selected which is less than the material strength. Appropriate settings can be found by consulting the attached feed diagram.
The machine’s setting is measured by means of two displacement transducers. The reading accuracy is 0.01 mm (digital) and can be read at the operator station.
Strip guide
The strip guide is installed between the straightening machine and the press. It takes the form of a two-sided roller cage, and represents a closed unit. The rollers are housed in the roller cage.
An infinitely-variable mechanical height adjustment allows an adjustment range corresponding to the changing infeed height of the press due to the variety of tools.
Also integrated is the loop control by an ultrasound sensor, which is installed between the two roller cages at the height of the connecting bars.
The sag of the strip is monitored with reference to both a maximum and a minimum value. End-of-strip monitoring is also performed.
Double hydraulic off-coiler
The coiler is assembled as a double coiler.
The coiler stand has a stable, low-distortion welded design and contains both the coiler shaft bearings and the drive mechanism. The coiler shaft, made in heat-treated steel, is fully equipped with anti-friction bearings, as a result of which the straightening machine only needs to provide a relatively low draw-off force. Fitted on the outside is the easily accessed brake, which is air-cooled. Expansion is performed hydraulically by means of splines, whereby the expansion force is reduced and stability increased by the large area of contact.
Automatic tension adjustment
The coiler is equipped with an automatic tension adjuster which prevents accidental slackening of the coil when the inner coil tension drops. This function can naturally also be turned off in order to prevent the innermost winds of the coil from becoming too badly deformed. With the stringent safety requirements of today, this function is absolutely essential.
Brake
The braking of the coiler is carried out pneumatically by solid disk brakes. The friction blocks run on bearings flexible to guarantee a large feeding area and to avoid a diagonal course.
The large diameter of disk brakes and the arrangement of the disk brakes outside of the coiler head offers more advantages:
- resistance to abrasion by low braking power
- low heating of the brake
