Mária Kapustová

INFLUENCE OF SELECTED CUTTING CONDITIONS ON CUTTING FORCES

The article presents achieved results of research focused on the influence of various factors modification on cutting forces at longitudinal turning of steel C 45 using two tools with different shape and geometry at constant values of feed and depth of cut. The individual components of cutting force were compared reciprocally, i. e. axial, radial, tangential and finally resulting cutting force depending on cutting speed.

The Rationalization of Production of Ring-Shaped Drop Forgings Using Computer Simulation of Closed-Die Forging Process

The rationalization of ring-shaped drop forgings production may be considered from different points of view. Important aspects of evaluation and selection of optimal production alternative are material and energy savings and issue of forging tool life. This contribution describes advanced technology of closed die forging without flash, which represents an effective method of manufacture of ring-shaped drop forging from steel alloy type 16MnCr5. This proposed method offers a cheaper possibility of production of mentioned forging piece resulting from saving of batch material. At present drop forgings with this shape are produced by an uneffective method, i.e. die forging with flash, which brings a considerable material loss. Simulation software determined for simulation of bulk forming processes have an important position at development of new advanced technologies of drop forgings production. A simulation program MSC.SuperForge described in this contribution was used in order to verify correct plastic flow of material in closed die cavity.

The Analysis of Temperature and Strain Rate Influence on Flow Stress of Mg Alloy AZ31

This contribution analyses influence of thermo mechanical conditions of magnesium alloy - type AZ31 forming on its flow stress. Temperature and strain/deformation rate belong to the essential thermo mechanical parameters of strain/deformation process. A testing cylinder made of selected Mg alloy was strained using pressure at warm temperatures within defined two degrees of nominal strain 30% and 60% and strain rate of 5 s-1. The pressure test at warm temperatures was conducted at testing temperatures 250, 300 and 350°C. It is important to explore the temperature influence on AZ31 alloy flow stress in order to reduce energy consumption of formed pieces production. Surface quality and precision of required dimension will improve, as well. The experiment was aimed at graphic evaluation of temperature influence on flow stress of Mg alloy AZ31B. Resulting form flow stress curve it is possible to read out its value for particular strain. These values are essential for calculation of forming force and work. For magnesium alloy AZ31 warm forming at temperature interval of 230 - 425°C is typical. The pressure tests were realized within the temperature interval of 250 - 350°C, i. e. at temperatures belonging to lower limit of recommended temperature interval, with the aim of acquirement as much information as possible on Mg alloy behavior at low forming temperatures.

The Description of Precision Forging Technology in Closed Die of Mg Alloy AZ31 Using Computer Simulation

Automotive industry is nowadays constantly strengthening its dominant position. Its primary objective is to reduce weight of automobiles in order to decrease fuel consumption and amount of harmful pollutant emissions. From the viewpoint of further development in the field of automotive industry, very interesting are the issues of die forgings production from light non-ferrous metals. This article describes research of precision die forging technology in closed die with regard to magnesium alloy type AZ 31. Given alloy type Mg-Al-Zn is suitable for bulk forming and is characterized by good formability at hot conditions. Results of this research may be applied to production of forgings with longitudinal shape, e.g. levers and connecting rods. In order to verify the design of forging technology in closed die for lever-shaped forged piece the simulation program MSC.SuperForge was used. Numeric simulation of die forging process confirmed suitable designed shape and dimensions of semi product and also correct material plastic flow in cavity of closed die.

The Verification of Material Plastic Flow at Optimal Warm Forging Temperature Using Computer Simulation

Warm forging is most commonly used for production of die forgings which are manufactured by means of precise forging. As compared to cold forging, warm forging enables to reduce forging forces size considerably. Development of warm forging technology is connected to formability and plasticity research of forged material at warm temperatures. This contribution brings a methodology for optimal forging temperature determination from recommended interval of warm temperatures used for chromium-manganic steel 16MnCr5. The given steel is appropriate for case hardening and precise die forgings production. For the purpose of verification of steel forgeability at the recommended interval of warm forging temperatures 600, 650, 700 and 750 °C technological test of upsetting according to Zidek is used. The main factor of plasticity for optimal warm temperature selection from examined temperature interval is value of reduction of area that was determined by tensile test. Numeric simulation of forging process in closed die confirmed correct plastic flow of steel 16MnCr5 at recommended forging temperature 700 degrees of Celsius.

The Importance of Forging Line Modernization for Material Flow in Drop Forge

This contribution proposes an optimization of material flow by means of modernizing of forging lines - type induction furnace / crank forging press / trimming press. The basis of design of forging line treatment is placement of hydraulic shear machine for shearing of heated bar to semi-products before respective forging of forged pieces. This method helped to remove previous redundant workplace for semi-products preparation, which causes reduction of technologic operations and substantial decrease of material flow in die forge. Proposed variant of material flow optimization brings economic profit by means of reduction of production times and fuels costs intended for pallets transport. Given save will be interesting for die forges as it contains also calculation of logistical effect.

The New Methodology of Working Load Classification in Engineering Operations

Working conditions in engineering operations are often characterized by a complex of negative factors, which at every moment load the human body during the active work with various intensity. Determination of the intensity of the workload is important for creation of workplace comfort, which is closely connected to workers’ contentment. The contribution presents a description and application of a mathematical model for determination of the workers´ complex loading at forging press workplace. Its a new and human way of evaluating work comfort, which can take into account the summary effect of all the negative factors at the workplace.

The Research of Forgeability for Warm Temperatures Using Simulation

At nowadays the interest of forging shops is focused on technology of accurate die warm forging. It is possible to reach higher exploitation of material, higher surface quality and higher accuracy of forgings in comparison to standard forging. The advance of warm forging relates to research of ductility and plasticity of forged material in warm temperature range. This paper provides the results of the research of 16MnCr5 steel forgeability in the interval of temperatures of warm forging. Steel alloy 16MnCr5 is proper for case hardening and for the production of precision die forging. In this paper the description of methodology for the proper interval setting of temperatures of warm forging for the given type of steel can be found. Practical test and a numerical simulation has proven the propriety of the examined steel for forging in the temperature interval 600, 650, 700 and 750 °C. For the steel forgeability verification in the recommended interval of warm forging temperatures, the technological test of upsetting according to Zidek was used.

Optimization of the Raw Part Shape for the “Fork” Production by Computer Simulation

The article showed procedure of forging technological flow design modification of real component “fork”, with using of computer simulation. By using of the primary technological process at production was produced failure forgings, checking simulation showed incorrect material flow in filling of die cavity, and therefore it was needed to raw part design modifications. These modifications were suggested on base results obtained from simulation, the results were abolition of defects, resolution of problem and correctness verification of final forging technological flow.