Miroslav Tomáš

Influence of the CAM Parameters and Selection of End-Mill Cutter when Assessing the Resultant Surface Quality in 3D Milling

The paper deals with the effects of CAM data needed to produce desired quality of shaped surfaces in forming dies making. In general, the input CAM data have strong influence to the final surface quality. The shaped surfaces 3D milling has been modeled as end ball milling of the surfaces with defined inclination. The end ball milling is the most common way to finish shaped surfaces. Directions of the milling tools motion and applied cutting conditions have been used to simulate data when setting milling strategies. The resultant machined surface quality has been identified in terms of the surface roughness. The paper introduces recommendations applicable to the programming of the different types of milling strategy when producing form surfaces.

Measurement of the Limit Strains on TS 245 Tinplate

The paper deals with measurement of limit strains for tinplate TS 245 made by US Steel with nominal thickness 0.3 mm. The FLC curve has been measured by implementation of Nakajima test on testing device Erichsen 145-60. The Nakajima test has been measured according to EN ISO 12004-2. Limit strains have been measured using 3D photogrammetric system Argus by GOM. Forming limit curve was evaluated in the software Argus. During test, some problems have been solved concerning friction on hemispherical punch which affected fracture position on the dome. Reached FLC curve was implemented in material database of PAM-Stamp 2G simulation software.

Tribological Properties of Coatings for Sheet Metal Stamping Dies

The conventional and innovative surface technologies are applied to sheet metal stamping dies in order to produce a composite material with properties unattainable in either the base or surface material. To select proper materials for forming dies the systematic evaluation of dies materials, their heat treatment and coatings are required. This paper deals with evaluation of plasma sprayed coatings Cr2O3, Al2O3 and WC12Co by pressure plate-ring test (tester T 05) and deep drawing process. Friction coefficients and seizure of these coatings were studied under dry and wet friction conditions. For different types of die rings (with and without ceramic coatings) the punching forces were measured during deep-drawing process. The results show that the main advantage of application of plasma sprayed coatings on the die contact surfaces under wet friction conditions compare to dies made of the tool steel may be the increase of seizure resistance of stamped part surface. The more significant difference in the friction coefficient values was not observed.

Local Tribological Characteristics of Steel Sheets for Microforming

The die radius represents the important local part of drawing die due to transferring contact loading under deep drawing. Within the experiments local contact pressure on die radius was researched using numerical simulation of strip drawn test and micro deep-drawing. Experimental research of strip drawn test was done using coatings with different alloying – under alloyed, optimal and slightly pre alloyed. Alloying level was evaluated by phase composition and % Fe in coating. Presented coatings were created on IF steel sheet DX54D. Experimental results of strip drawn test were used to verify strip-drawn test numerical simulation. Based on numerical simulation results, contact pressure on drawing die radius at deep drawing of cups Ø 50 mm and Ø 15 mm were observed.

Milling strategies evaluation when simulating the forming dies’ functional surfaces production

Abstract The paper deals with selection and evaluation of milling strategies, available in CAM systems and applicable when complicated shape parts are produced, such as forming dies. A method to obtain samples is proposed and this stems from real forming die surface machined by proper strategies. The strategy applicability for the whole part – forming die – is reviewed by the particular specimen evaluation. The presented methodology has been verified by machining model die and comparing it to the production procedure proposed in other CAM systems.

The Numerical Simulation of the Deep Drawing Process and its Verification by the Adaptation of the Laminated Tooling Concept

The paper deals with numerical simulation and its verification when designing production the gutter corner for the rainwater systems. The deep drawing process has been simulated in Pam Stamp 2G software by ESI Group and the part and blank geometry, friction and process parameters have been optimized. Then, those parameters and the die geometry were verified by experiment when lamination tooling concept has been adapted. The metal laminated tooling technology was used for production of the punch by applying the laser cutting, assembling and joining. The experiments were done using hot deep galvanized steel sheet DX54D+Z with thickness 0.6 mm.

LASER WELDING IMPACT ON DEFORMATION PROPERTIES OF STEELS WHEN USED FOR CAR BODY PARTS

The energy absorption at crash, usually described by stiffness and crashworthiness, is the key request for the car-body components, considering the material they were made from. The modified 3-point bending test with fixed ends has been developed in our department to assess materials for the carbody parts. The force and punch path are measured and used to calculate stiffness and crashworthiness. Experiments were performed on high strength low alloyed steel H220PD, dual phase steel DP 600 and austenitic stainless steels AISI 304 for base material and specimens welded by solid state fiber laser YLS-5000. Based on the experiments and analysis, the austenitic stainless steel is better to use for car body components of frontal deformation zones. Otherwise, the passenger’s compartment is better protected by applying dual phase steel for car body parts when side impact occurs.

ANALYSIS OF COATED STEEL SHEETS’ RESISTANCE TO CORROSION AFTER PLASTIC DEFORMATION

The automotive industry is influenced by customers’ requests, including safety and lifetime improvement, weight and emissions decreasing. The paper presents corrosion resistance improvement of car-body components by steel sheets coated with Zn-Al-Mg coating. Specimens coated with GI and Zn-Al-Mg coatings have been deformed by stretching (Erichsen test) and 3-point bending tests to 90 and 180. After deformation they have been tested in aggressive corrosion atmosphere of salt spray in corrosion chamber. Reached results showed better corrosion resistance of Zn-Al-Mg coatings when compared to standard Zn coating GI.

Laser-beam welding impact on the deformation properties of stainless steels when used for automotive applications

Abstract Materials other than standard and advanced high strength steels are remarkable for the thin-walled structures of the car-body in recent years in order to safety enhancement, weight and emission reduction, corrosion resistance improvement. Thus, there are presented in the paper the deformation properties of laser welded austenitic AISI 304 and ferritic AISI 430 stainless steels compared to these one measured for the high strength low alloyed steel H220PD. The properties were researched by tensile test and 3-point bending test with fixed ends on specimens made of basic material and laser welded one. The specimens were welded by solid state fiber laser YLS-5000 in longitudinal direction (the load direction). The deformation properties such as strength, stiffness and deformation work were evaluated and compared. The strength and stiffness were calculated from tensile test results and the deformation work was calculated from both, tensile test and 3-point bending test results. There has been found only minor effect of laser welding to the deformation properties for high strength low alloyed steel H220PD and austenitic stainless steel AISI 304. Otherwise, the laser welding strongly influenced the deformation work of the ferritic stainless steel AISI 430 as well as the elongation at tensile test.

Evaluation of Limit Deformations of Zn Coated High Strength Steel

The paper presents the evaluation of limit deformations by the tensile test of notched specimens to measure the left side of forming limit curve. The notch radii R5, R10, R17.5 and R25 were machined on the specimens of 40 mm in width. The limit deformations have been assessed for Zn coated high strength steel TRIP with thickness 0.76 mm. Two types of deformation grid were electrochemically etched on the specimens: circles with diameter of 2 mm and the pattern of dots with diameter 0.5 mm and spacing 1 mm. The tensile test of notched specimens has been also numerically simulated. The experimentally measured limit curves have been compared to the mathematic Swift-Hill model.