FOCUS ON FLOW-FORMING usually consist of a rim ring and a wheel disk . The rim ring can be produced in the car sector , and both parts can be produced in the truck sector using the flow-forming process . Work hardening improves the microstructure in the material and therefore increases final strength .
“ We can reduce the material cross section at certain points and flexibly adjust it to the load requirements of the wheels ,” said Nillies .
Weight-optimised rim rings
The company offers two different machine production series and flow-forming processes - the FFM series for backward flow-forming and the RSC + RC machines for biconical forward flow-forming . The difference here is the feed direction of the rollers and the flow direction of the material . Both form steel wheels without a tube , in large or small quantities .
Manufacturers can produce cylindrical components such as the rim rings on the FFM machine . For exact ring widths , measuring devices record tolerances in the circular ring which are compensated by the machine control system - without additional trimming . “ A modified cross-section of the output sheet metal ring saves weight ,” explained Nillies .
How does that look in practice ? He pointed to the equipment . A conveyor belt transports the preform , which was cut from strip , rounded and welded into a sheet metal ring , to the measuring device . If everything fits , a robot picks up the component and places it in the machine ’ s loading device . There , the preform is automatically pushed onto a mandrel and fixed . The main spindle drive sets the mandrel with preform in a turning motion . Under CNC control , the roller , which runs in the opposite direction , flow-forms the material in an axial direction . The wall thickness of the preform is reduced to the desired thickness . The final component length is permanently monitored and stopped in the machining program when the final rim ring width is reached . A scraper on the machine side then removes the finished part from the tool mandrel onto the unloading chute .
Finally , a robot takes the flow-formed component out of the machine . The automatic quick-clamping device for tool mandrels and rollers minimizes set-up times and thus increases cost-effectiveness .
“ With cylindrical counter-rotating flowforming , we can use universally applicable tools for different wheel widths ,” explained Nillies . “ The preform is easy to measure ; there is a high degree of work hardening and no need to cut off excess material . That ’ s what makes this machine so popular with our customers ”.
Forward flow-forming
“ With biconical forward flow-forming , the
Above : Bi-conical forward flow-forming by Leifeld ’ s RSC and RC series machine process .
preforms for rim rings can be produced not only at an optimised , but also at an optimal , weight . However , this is only possible for biconical components with a cylindrical inner diameter and axial clamping range - such as the drop-centre area ,” explained the company .
Leifeld offers the RSC + RC series for this purpose . A loading device or a robot picks up the preformed component and places it in the machine . There , it is picked up by two mandrels in a form-fit and force-locked manner . Two co-rotating rollers each press the material in the direction of the axial feed in opposite directions . The area not yet involved in the forming process is pushed in front of the roller .
“ The machine therefore ensures symmetrical distribution of forces and a very high degree of rotational accuracy for the component ,” said Nillies .
With forward flow-forming , no additional
Above : A view of the working area of the Leifeld RSC Series with four flow-forming rollers .
calibration expansion and no section length measurement is required . Greater preform and sheet metal tolerances can also be used . The excess material is then removed in another machine so that the desired material thickness and length can be achieved . The component is therefore free of weight differences resulting from the sheet metal thickness tolerance of the prematerial .
“ Manufacturers can use our machines to design the wheels as they are required by vehicle producers - light , with a high payload ,” promised Nillies . “ They can therefore safely withstand increasing competitive pressure in the future as well .” n
The weight-optimised rim ring is produced by flow-forming technology .
Left : Benedikt Nillies in front of Leifeld machine .
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In 130 years of business , Leifeld Metal Spinning has manufactured over 6,150 machines and delivered them to 60 countries . The company has also filed for patents on more than 140 inventions to date .
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