Title

Description

    Designing and manufacturing active surfaces to exact specifications

    Enormous time savings in the tryout phase

    Because a large amount of time and effort is supposedly needed for design, active surfaces are often fully designed for only one side of the sheet metal (e.g. for the die). Offset dimensions (= sheet metal thickness) are then factored into the NC programs for NC manufacturing. Often stock allowances are also used in the NC programs to account for thinning effects and reliefs. Although this procedure quickly yields an initial result, it also requires an enormous amount of manual effort in the spotting presses and usually in additional iterations in tryout.

     

    Tebis offers automated design functions with which active surface designers can include sheet thickness, thinning effects and reliefs in the design of the CAD active surfaces. This results in absolutely realistic tool sets – accounting for all known and simulated forming effects. This enables time savings of hundreds of hours in NC programming, machining and tryout.

    Usual method: Pressure surfaces (positive allowances) and reliefs (negative allowances) are not designed to meet exact specifications, but rather are milled in the active surfaces of the sheet metal die based on NC stock allowance attributes. The milled result (red surfaces) doesn’t correspond to the CAD model (dotted surface).
    Tebis method: Pressure surfaces (positive allowances) and reliefs (negative allowances) are designed precisely and with transition areas in the CAD design (green surfaces). The CAD model is produced on the milling machine. The milled die components and the CAD model are identical.

    Usual method

    Visible edges in milled die surface

    Usual method

    Result after extensive grinding work 

    Tebis method

    Die surface with no steps and without manual grinding work

    Reduced additional effort in design
    Time invested in design pays for itself in manufacturing and tryout
    Fast and reliable manufacturing
    Exact active surfaces are the prerequisite for NC automation and reliable simulation and for the use of high-feed cutters (HFC)
    Short manual tryout times
    Finished die surfaces with no visible edges or transitions

    Radii

    For drawing operations: Relieve and flatten at the click of a button 

    For the die maker, relief means the reduction of rounded areas in concave areas of the matrix, punch, blank holder and all small parts, so as to ensure that the sheet metal in these areas is only contacted by one side of the die on forming.

    This effect is achieved in convex active surface areas by flattening the radii.

    Modify your active surfaces in the CAD design wherever possible. This lets you stabilize your overall process from the drawing simulation to the tryout press. Changes in rounded areas in the CAD design are quickly and precisely implemented in the die by means of NC programs and can be modified in a controlled manner to facilitate a stable process.

    Tebis automatically detects radii and roundings and reduces the radii in the rounded areas at the click of a button, thereby creating tangential transitions to the adjacent surfaces.
    The user interactively performs graphical modifications to convex roundings in the active surfaces in real time. The Tebis user determines the degree of the change with the control arrow.

    Pressure surfaces and reliefs

    For drawing operations: Fit areas together with smooth transitions

    Pressure surfaces are required for large surface areas of the die in which the sheet metal must be held more securely during the drawing operation. Conversely, the sheet metal has greater freedom to stretch and expand, i.e. so that no pressure is exerted on the sheet metal. Free-form surfaces are designed for this purpose.

    The video shows how Tebis automatically calculates positive and negative allowances for red areas. Green areas remain unchanged; orange areas are transition areas.
    The before and after differences are rendered visible with a comparison function and can be measured by the user.

    Outline surfaces

    For trim operations: Automatically generate outline surfaces 

    For designing lower trim steels, the Tebis active surface designer creates outline surfaces at the click of a button. These surfaces already include the cutting gap and reliefs. A constant trim edge width is also included. The calculated surfaces are then used for the solid design of the lower part of the die.

    Tip: You can also use the Tebis automatic small-part process for designing your trim steels.

    Tebis automatically calculates outline surfaces (light areas) with reliefs (dark areas) from 2D and 3D curves.
    In the press, the sheet metal (green) is trimmed by the trim steel on the lower steel.

    Tip: You can also use the Tebis automatic small-part process for designing your trim steels. 

    Trim and coining steels

    Automatically design small parts with all offsets, reliefs and bores

    Trim steels are the small parts of a sheet metal die and can be designed and manufactured in a standardized and largely automated process. The Tebis automatic design process uses surface and solid geometry. It generates form and outline surfaces with offset and reliefs and cuts everything to exact solids with automatically generated extension and overrun surfaces.
    The bores and fits required for securing the trim steel result from the assembly specification of the solid system. The cover surfaces needed to produce the trim steels by milling are created automatically.

    The highly automated Tebis small-part process uses specifications from the solid design and the active surface design, enabling the user to easily generate precise and fully designed trim steels.
    Bores and fits must first be closed to manufacture the trim steels on milling machines. Tebis automatically creates the cover surfaces.
    Tebis uses bore features for all bores and fits, accessing the Tebis process library which is built up during process structuring. There are corresponding NC machining sequences for each bore feature, with information on tools and cutting data.

    Press deflection

    Designing compensation for gravitational forces

    The upper sections of large-scale forming dies are subjected to gravitational forces that cause undesired defection of the die depending on the rigidity of the overall system. Tebis automatically and reliably compensates for this physical effect in the active surfaces. The Tebis morphing technology automatically morphs complex, free-form topologies to the specifications of an easily formulated morphing rule. 

     

    The die sags in the original state, with the result that the air gap to the punch is smaller in the center than around the outer area.
    After compensation for press deflection, all surfaces have been changed minimally. The compensation is the greatest in the middle of the die, where the greatest deflection has been calculated.

    Additional links

    CNC automation
    Tebis Automill® evaluates the digital CAD part model and accesses a previously stored structure of digital representations of the company's manufacturing environment and the manufacturing knowledge stored in templates in order to calculate the NC programs.
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    Circle-segment cutters

    Circle-segment cutters have a special geometry that saves you up to 80 percent of the time required for prefinishing and finishing compared to machining with ball cutters. Tebis supports all these kinds of efficient high-performance tools – because each tool can be modeled with precise attention to detail in the virtual CAM environment. 

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    Die manufacturing

    Many OEMs and medium-sized companies around the world have successfully implemented the Tebis solution for die manufacturing. With powerful CAD and CAM functions and highly automated processes, they shorten their throughput times and minimize manual reworking in tryout. 

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    Compensating springback in CAD

    While mechanical compensation introduced by grinding the die requires an enormous time expenditure, the approved sheet metal die geometry can be arrived at far more quickly through the implementation of deformation technology in the CAD surfaces.

    More...

    Even if just one pressure area was overlooked in the past, the correction cost us up to 10,000 Euros. Today, for example, we install dies for doors that we previously had to rework directly in the press for roughly 160 hours.

    Roland Schöbel, head of machining, Volkswagen AG, Germany

    Tebis has helped us to improve our overall production process; we have become faster and more flexible and we now manufacture more efficiently and reliably. All this thanks to the high consistency of the software, which no one else can offer in this form.

    Merima Präzisions-Werkzeugbau GmbH, Germany
    Challenges in Sheet Metal Draw Die Manufacturing

    No more visible edges or steps in the die surface: Tebis active surface preparation includes compensation of sheet metal thinning, incorporation of pressure surfaces and free design of negative radii. Specialized functions enable programming without virtual wall thicknesses.

    Read full article
    Tebis white paper: Evolution in sheet-metal forming

    Tebis has developed functioning software-supported processes specifically for die manufacturing to enable the production of top-quality class-A surfaces and to automate manufacturing of small parts. Both processes verifiably reduce manufacturing expenditure, thanks to standardization and the integration of individual manufacturing knowledge. 

    Download white paper