Laboratory for forming technology



"Rethinking constructively, manufacturing efficiently, productive forming"


Teaching

"Rethinking constructively, manufacturing efficiently, forming productively" - under this motto, the most important processes of solid forming and sheet metal forming are taught in a practical manner in the laboratory for forming technology and their application possibilities and limits are demonstrated.

In the current semester, various laboratory exercises are offered for MAB-PS students (6th semester) as well as for the area of compulsory electives (MAB-AM, WIM). In the last few years, the number of enrolments has risen continuously and is currently around 40 students per semester.

The individual laboratory topics are:


Flow curve determination

- The material-specific flow curves of the solid and sheet metal materials used are determined by means of cylinder crush tests and flat tensile tests. They serve to characterise the forming behaviour and provide the necessary characteristic values for the calculation of forming forces.


Deep drawing

– Circular sheet blanks are formed into rotationally symmetrical "cups" with and without flanges. The force-displacement curves measured in the process are compared with the results of a computer software which outputs a process curve calculated theoretically from material and tool data only. In addition, the local change in sheet thickness or the degree of forming on the drawn part is determined non-destructively on the basis of circular grid patterns via their change during deep drawing by means of a forming limit analysis.


Extrusion

– Cylindrical steel specimens are formed into "cups" (sleeves with bottoms), varying the specimen height and bottom thickness of the extruded parts. From the associated force-displacement curves, the work requirement and the deformation efficiency can be calculated with the help of the characteristic values from the flow curves. The determined test data are compared with the results of an FE-supported forming simulation of the impact extrusion process and evaluated.


Bending

- Using a sample part (stacking box), the required manufacturing steps (calculation of the blank, determination of the bending sequence taking into account the elastic recovery, etc.) are determined and verified with the support of bending simulation software.


Clinching

– Sheet metal strips of different thicknesses made of steel and aluminium are joined in different pairs by means of clinching, whereby the number of clinching points and their arrangement are varied and the position of the sheet metal strips (e.g. steel on the punch side - aluminium on the die side) is swapped. The connected sheet metal strips are then loaded on the tensile testing machine until the clinch points fail under shear stress. The associated force-displacement curves enable defined statements to be made on the optimisation of clinch joints.

 

Interesting techniques in the laboratory for forming technology

Wet cutting

The laboratory has a high-pressure water jet cutting system that enables the "cold" cutting of a wide variety of materials and the production of parts with complex cutting contours. With up to 3600 bar jet pressure and added abrasive sand to enhance the cutting effect, steel and aluminium sheets, tool steel plates, but also plastics as well as composite materials and even ceramic materials can be cut precisely and at high travel speeds. The system is used on an ongoing basis as part of inter-lab project work and also as a supplement by the company workshop. In addition, some components for the Formula Student Team (e.g. steering wheel, trim parts, brake disc segments) have already been successfully manufactured on it.

 

Cold clinched

Clinching is the name for a forming joining process for the force-locking and form-fitting connection of sheet metal without additional elements (as in punch riveting) and without the influence of heat (as in welding). This means that sheet materials of different types (e.g. steel and aluminium) and material thicknesses or even coated sheets can be joined efficiently. The laboratory's own clinching press thus enables the production of finished sheet metal parts.

 

Freshly pressed

The hydraulic 100-t press can be used universally. The tools available in the laboratory can be used for upsetting or cold extrusion of solid blanks, and sheet metal can be further processed by deep drawing, coining or punching. By means of special software, displacement measuring systems and built-in load cells, associated force-displacement curves can be recorded in each case. The press is equipped with a hydraulic counter-holder device (drawing cushion), which allows uniform deep-drawing for large drawing depths, rectangular drawn part shapes or even materials that are more difficult to form, such as stainless steel.

 

Equipment

Cutting

  • OMAX waterjet cutting system MAXIEM 0707 (working range: 700 mm x 700 mm)
  • SCHRÖDER-FASTI Technologie GmbH swing cutting shears (cutting capacity: 1000 mm x 5 mm steel)

Testing / measuring

  • Zwick/Roell tensile/compression testing machine (test force in tensile/compression direction: 50 kN)
  • Krautkramer MIC 20 hardness tester (test method: UCI)
  • Feinprüf Perthen GmbH roughness tester
  • Peekel Instruments AUTOLOG 3000 measuring amplifier with measurement data acquisition (connection option:
    12x strain gauge full bridge, potentiometric transducers, thermocouples type E, J,K, T, R and S, PT100, voltages +- 10 V, current signals +-50 mA, sensor supply voltage: 2.5 V
    6x inductive displacement transducers in full and half bridge circuit, measuring range: +-100 mV/V, +-500 mV/V, carrier frequency: 5 kHz, sensor supply voltage: 4 V)

Forming

  • Schuler AG hydraulic drawing and punching press 1000 kN
  • Eckold C-frame upright machine type DFG 500/150 "clinching press or clinching press" (press force 150 kN)
  • CoastOne Oy servo-electric press brake with spindle drive (press force 440 kN, maximum bending length 1300 mm)
  • Beading machine "flanging machine" RAS EasyFormer 12.35-2 (sheet thickness maximum 1.75 mm at strengths up to 400 N/mm², roller centre distance 63 mm)

Simulate

  • DEFORM-3D (FEM simulation software for simulating multi-stage solid forming processes)
  • Metalix MBend (software for programming and simulation of CNC-controlled bending processes)

Impressions

The team

Laboratory engineer

Non-Public Person

Focus points of work

Until the end of 2014, numerous research projects were carried out together with companies, institutes and universities. The focus was on deep-drawing with formless solid materials supported by active media. This forming technology, which has been further developed in third-party funded projects over several years, enables the production of drawn parts with complex shapes (e.g. also with undercuts) with reduced tool change times (only one tool half is exchanged) and clear advantages compared to deep drawing processes with liquid active media (no external aggregates and seals required). In recent years, the focus has shifted to practical experience in product and tool development, from the design of components and tools, construction and testing to production in the field of forming technology.


The aim is to replicate the entire process chain of industrial sheet metal forming on a laboratory scale and make it usable for the university. This includes the flexible production of sheet metal blanks, further processing by bending or deep drawing and the final joining operation to produce finished components. In the future, the processes are to be expanded by possibilities of so-called incremental sheet metal forming (drawn part production by means of CNC-controlled step-by-step forming in defined path lines driven by a "pin").