The probability that you encounter our rolling technology every time you get into a car is relatively high.
A number of global leading OEMs rely on FUHR rolling mills for the production of cold rolled special profiles, which enter a value creation chain for products such as springs for the retraction of front seats and safety belts, windscreen wiper blades, as well as reinforcements for internal trim.
Our rolling technology is also increasingly being deployed in the production of compression and oil rings for internal combustion engines, as well as in high performance engines through the use of thread inserts for the durable joining of light alloy components.
These are just a few of the highly diverse areas of vehicle manufacturing in which our ultramodern and efficient rolling technology is at work.
Today’s truck and car engines generally comprise three piston rings per cylinder. Their design characteristics depend on the position on the piston and thus, also their function.
The top ring, which is closest to the combustion chamber, is known as the compression ring. This ring must primarily seal and conduct heat.
The lowest ring, the oil ring, wipes lubricating oil off the cylinder wall and thereby regulates the oil film on which the upper rings slide during the stroke.
The second or middle ring seals combustion gases and can significantly influence engine blow-by via interaction with the movement of the first ring. This second ring also takes on a considerable role in controlling engine oil consumption. The oil film must both be sufficient for adequately good tribological conditions as well as thin enough to keep the loss of oil by evaporation low.
The oil film in the area of the upper piston rings is less than a thousandth of a millimeter thick and is thereby less than the roughness of piston and cylinder.
Profile wires are rolled by FUHR rolling mills, and then bent into piston rings in the next process step. The micrometer precision achieved in the rolling process necessitates only a very slight mechanical finishing step.
STARTER RING GEAR
A starter ring gear can be found in almost every conventionally built vehicle engine. It is mounted on the external perimeter of the clutch and is fixed by shrinkage or welding. The electric starter motor engages the teeth of the starter ring to start the engine.
FUHR rolling mills roll a raw rolling wire of medium carbon content into a profiled wire with a trapezoidal cross section. From this profile wire, a ring is then bent and welded. In further processing steps the rings are machined, the teeth are cut, hardened and tempered.
The use of profile wire reduces the loss of material since only minimal mechanical processing on lathes is required.
THREAD INSERT (HELICOIL)
Thread inserts were originally developed for the repair of damaged threaded holes. Today, they are often used to strengthen threaded holes so as to allow highly loaded screwed connections in light alloys. An example in automotive construction is the bolting of cylinder heads to aluminum engine blocks. In aircraft construction, tens of thousands of thread inserts are required per aircraft.
There are various types and structural shapes of thread inserts. If the thread in the hole has already been tapped, flexible wire helices, known as coil thread inserts, are used.
These coil thread inserts are formed from profiles wire into an elastic spiral. The tang, which is necessary for assembly, is severed at the notch (predetermined breaking point) to provide a through-hole thread.
The prototypical wire thread insert bears the trade name Helicoil and was developed in the late 1940s in the USA. Today, the Helicoil is manufactured, further developed and sold by the company Böllhoff und Emhart Teknologies.
FUHR rolling mills are used to roll the diamond section profile wire used to produce the thread inserts from stainless steel circular wire. The high precision achieved by the rolling process ensures a precise fit between thread insert and screw.
Spiral springs are used in a range of applications in automotive production. Examples can be found in the areas of seat adjustment (adjustment of the backrest of the front seats) and in safety belts (roll-up function for the safety belt).
With FUHR rolling mills, flat wires are rolled from high carbon steel round wire. Here, the spring properties are generated either by the strain hardening achieved in the rolling process (cold rolled springs for safety belts) or from subsequent heat treatment (oil tempered seat inclination springs).
Conventional screen wipers consist of a metallic wiper arm that is attached to the wiper shaft. A joint allows the wiper blade to be tilted away from the screen. For the flat screens of earlier generations of automobiles, it was sufficient for the wiper blade to be a stiff metal rail with an attached rubber profile.
In the case of the curved vehicle screens that have long become standard, manufacturers divide the wiper blade into several jointed segments that press the rubber profile against the screen. To distribute the contact pressure evenly, there are two thin, elastic stainless steel inserts in the rubber profile.
In addition there are non-segmented flat wiper blades (also known as aero wipers – see photo) on the market. In recent years, these flat wiper blades have increasingly become standard equipment in the car area.
The precisely formed arch of these single blade wipers, with the curved profile resulting from the cold rolling process, permits them to fit snugly on the screen over the whole speed range and thereby guarantees perfect wiping performance at all times.
With FUHR rolling mills, both the stainless steel inserts of the segmented wipers and the arch of the single blade wiper are rolled from round wire.
With modern vehicle engines, higher torques, higher combustion pressures and stricter emission regulations lead to increasing irregularities of engine rotation and therefore to stronger vibration impulses in the drive chain. Higher demands for comfort and engine smoothness, as well as measures for the protection of the transmission require extremely high performance torsion dampers.
Consequently, so-called dual mass flywheels are used between crankshaft and clutch. The two halves of this flywheel are connected together with two or four circularly curved spiral pressure springs.
With FUHR rolling mills, round wire is slightly flattened on two sides before entering the spring coiling machine, in order to reduce the unit length of the springs without significantly reducing the spring rate.
FLAT FLEXIBLE CABLE
A flat flexible cable is a multicore cable in which the cores are not bundled inside a circular insulating sheath, but run parallel to one another. It is mainly used to connect multiple signal wires in electronic components and computers. There are also applications in the automotive industry, e.g. the airbag cable in the steering wheel.
Flat flexible cables offer the advantage that very many conductors can be connected with little effort thanks to insulation displacement technology with a male header, a solder adapter or another connector, instead of having to strip and then solder each one. Crosstalk is also reduced in ribbon cable as compared with round cable, and can be controlled better by the arrangement of the signals and the use of ground conductors between critical signals.
With FUHR rolling mills, the flat wires for these ribbon cables are processed from round copper wire. Here, special demands are made with regard to the precision and cleanliness of the surface, which are important for further processing.
There are few engine components that are exposed to such high loads and tribological stresses as the valves and their associated parts.
At temperatures up to 800 °C, the red hot exhaust valves hit the valve seats over 70 times a second and have to withstand the surrounding hot and corrosive exhaust gases. On every single valve operation, enormous acceleration and deceleration forces are generated by the strong valve springs.
Together with their seats, springs and guides, valves form a closed system that must withstand the highest stresses.
With FUHR rolling mills, profile wires are rolled that are processed further into valve collets. These collets fix the valve spring cap on the valve stem.
RETAINING RING (CIRCLIP)
A circlip or retaining ring, sometimes called a Seeger ring (after an important manufacturer), is a machine element for the axial location of bolts in bores or of components such as roller bearings on shafts or axles.
Accordingly, there are internal retaining rings for mounting in a bore (with ends pointing inwards) and external retaining rings for mounting on a shaft (with ends pointing outwards).
These rings are standardized parts. The rings encountered in mechanical engineering are standardized according to DIN 471 for shaft grooves and in compliance with DIN 472 for bore grooves. There are also special parts which are used in high unit volumes in the automotive industry.
In the simplest case a retaining ring is bent from round wire and curved around twice at the ring ends so that the ring gap can be closed for assembly with circlip pliers. The design standardized according to DIN 471 and DIN 472 is punched out as a flat ring and ground, and has two holes for assembly and disassembly by means of special circlip pliers.
With FUHR rolling mills, high carbon steel round wire is rolled into slightly trapezoidal wire with straight sides and relatively sharp edges. The trapezoid form is matched to the curvature radius so that a constant rectangular section is produced by the bending process. A finishing operation to adjust the size is not necessary.
Rolling bearings generally consist of two bearing rings with integrated raceways. Rolling elements are arranged on the raceways between the rings. The rolling elements can be balls, cylindrical rollers, needle rollers, tapered rollers or barrel rollers.
A cage generally guides the rolling elements, keeps them regularly spaced apart and prevents contact between them. With needle rollers and rimless spherical roller bearings the cage additionally provides location for the axis of the rolling element. If the bearing is separable, the cage holds the rolling elements together and thus simplifies the installation of the bearing.
The standard material for sheet cages is steel, as well as brass for some applications. There are solid cages made of brass, steel, laminated fabric and other materials. Cages in thermoplastics are also widespread, especially those in glass fiber reinforced polyamide.
Raceways and rolling elements are mostly made of through-hardened chrome steel, though case hardening steel is also used. Special bearings for extreme operating conditions – load, rotational speed, temperature, corrosion – consist of high temperature and/or stainless steels, plastics, ceramics as well as other materials.
With FUHR rolling mills, low carbon cold-rolled slit strip is rolled into profiled strip which serves as the input material for bearing cages. After rolling, the slots for the rolling elements are produced by punching and rings produced by bending and welding.
DRIVE TRAIN (CVT)
The task of the CVT (Continuously Variable Transmission) chain in a drive train is to transfer power from one pair of conical pulleys to the other. The chain consists of multiple links which are flexibly connected to each other by cradle-type joints. This relatively simple design, optimized in every detail, is the key to the special strength of the chain in torque capacity and efficiency.
Because of its generally modular construction, today’s CVT chain technology can cover the whole torque range from compact cars (from about 100 Nm) right up to the higher middle class as far as installation space and load are concerned.
The strengths of a CVT transmission are high-torque capacity combined with a wide ratio range, a very good level of efficiency in all ratios and load conditions, a robust construction proven in mass production as well as acoustic optimization by means of adjustment of the chain plate sequence.
With FUHR rolling mills, both the bolts and the link plates are rolled. Here, particularly great emphasis is placed on precision, since the slightest error will significantly impact on the total length of the chain due to the large number of chain links.