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EN
The article presents the investigations of 7xxx aluminium alloys performed by the method of thermal and derivational analysis. The studies made it possible to identify the effect of the changes in the Cu concentration, the total Zn and Mg weight concentrations and the Zn/Mg weight concentration ratio on their crystallization process: the cooling as well as the kinetics and dynamics of the thermal process of cooling and crystallization. Metallographic studies were performed on the microstructure of the examined alloys and their HB hardness was measured. The evaluation of the changes was presented in reference to the model alloys EN AW-7003 and EN AW-7010, whose microstructure under the conditions of thermodynamic equilibrium are described by the phase diagrams: Al-Zn-Mg and Al-Zn-Mg-Cu. The performed investigations confirmed that the hardness HB of the examined alloys is mainly determined by the reinforcement of the matrix αAl by the introduced alloy additions and the presence of phases Θ(Al2Cu) and S(Al2CuMg) rich in copper, as well as η(MgZn2), in the examined alloys' microstructure. The increase of the amount of intermetallic phases precipitated in the microstructure of the examined alloys is caused, beside Cu, by the characteristic change of Zn wt. concentration and Mg. It was proposed that the process of one-stage thermal treatment of the examined alloys be introduced at a temperature of up to tJ-20 °C, which will prevent the exceedance of the solidus temperature.
EN
The results of estimation of home scrap addition in charge influence on durability and wear of casting instrumentation life in the high-pressure casting technology using the hot chamber machine of alloy of AZ91 are presented. The wear of the following elements of the casting instrumentation so-called "casting set" as: syphon, plunger, sliding-rings, nozzle and injection moulding nozzle was estimated. A wear was estimated quantitative by registering the number of mould injections for different charges to the moment of element damage supervision. A damage had to be at such level that liquidated an element from further exploitation and necessary was an exchange on new or regeneration. In a final result allowed it the detailed determination of durability of the applied rigging elements in dependence on the type of the applied type of melt. It is noticed, that together with the increase of home-scrap participation in the charge wear of pressure machine instrumentation elements increases.
EN
The study discusses the issues connected with the production of thin-walled ceramic slurry in the replicast cs technology. In the ceramic mould production process, a special role is played by the liquid ceramic slurry used to produce the first layer of the mould. The study examines selected technological properties of liquid ceramic slurries used to produce moulds in the replicas cs technology. The ceramic slurries for the tests were prepared based on the binders Ludox Px30 and Sizol 030, enriched with Refracourse flour. The wettability of the pattern's surface by the liquid ceramic slurry and the dependence of the apparent viscosity on the ceramic flour content in the mixture were determined. The wettability of the pattern surface by the liquid ceramic slurry was determined based on the measurement of the wetting angle. The angle was determined by means of an analysis of the computer image obtained with the use of a CDC camera.
EN
The paper presents the results of research on the determination of the effect of pouring temperature on the macrostructure of the castings subjected to complex (surface and volume) modification and double filtration. Tested castings were made of post-production scrap (gating system parts) of IN-713C superalloy. Tests included the evaluation of the number of grains per 1 mm2, mean grain surface area, shape factor and tensile strength. Casting temperature below 1470 °C positively influenced the modification effect. The grains were finer and the mechanical properties increased, especially for castings with thicker walls. On the other hand, manufacture of thin walled castings of high quality require pouring temperature above 1480 °C.
EN
The aging granulate is to activate the blowing agent during the manufacturing process to granulate models can re-expand and shape the model of well-sintered granules, smooth surface and a suitable mechanical strength. The article presents the results of studies which aim was to determine the optimum time for aging pre-foamed granules for pre-selected raw materials. The testing samples were shaped in an autoclave, with constant parameters sintering time and temperature. Samples were made at 30 minute intervals. Models have been subjected to flexural strength and hardness.
EN
In current casting technology of cored, thin walled castings, the modifying coating is applied on the surface of wax pattern and, after the removal of the wax, is transferred to inner mould surface. This way the modification leading to grain refinement occur on the surface of the casting. In thin walled castings the modification effect can also be seen on the other (external) side of the casting. Proper reproduction of details in thin walled castings require high pouring temperature which intensify the chemical reactions on the mould – molten metal interface. This may lead to degradation of the surface of the castings. The core modification process is thought to circumvent this problem. The modifying coating is applied to the surface of the core. The degradation of internal surface of the casting is less relevant. The most important factor in this technology is “trough” modification – obtaining fine grained structure on the surface opposite to the surface reproduced by the core.
EN
The work presents the test result of the influence of cooling rate on the microstructure of AZ91 alloy, Vickers micro-hardness and Brinell hardness. Studies cooling and crystallization of AZ91 alloy was cast into the ceramic shells pre-heated to 180°C and then air-cooled at ambient temperature or intensively super cooled in the liquid coolant. The TDA method was applied to record and characterize the thermal effect resulting from the phase transformations occurring during the crystallization of AZ91 alloy. The kinetics and dynamics of the thermal processes of crystallization of AZ91 alloy in the ceramic shells were determined. Metallographic tests were performed with the use of an optical microscope. A comparison of these test results with the thermal effect recorded by way of the TDA method was made. Influence of cooling rate of AZ91 on HV0, 01 micro-hardness and Brinell hardness alloy was examined.
EN
The work presents the research results of the influence of the selected technological factors on the improvement of bimetallic castings alloy steel-silumin. The following alloy steel grades were used for the research: X6CrNiTi18-10, X39Cr13 and HS6-5-2. The sets of the mentioned steel grades were alphinated in silumin AlSi5 and were poured with this silumin or complex silumin AlSi5Ni5Cu4MgCrMoWV into the casting mold obtaining bimetallic castings as a result. Moreover, the following technological factors of the process of bimetallic casting production were analyzed: the time from removing of the set from the alphinizing bath till pouring it with the silumin into the casting mold “τp”, the temperature of the initial heating of the casting mold “t2,0” and the temperature of the silumin for pouring of the casting mold “tz”. It follows from the presented results that the best connecting quality of the analyzed castings is obtained when using: the possible short time “τp” and low temperature values “t2,0” and “tz”.
EN
The article presents the results of studies concerning the selection of the chemical composition of the new ecological copper alloys for fittings. It was analyzed, among other things, the impact of the content of bismuth, aluminum, iron and boron. Their solidification process was characterized on the grounds of thermal and derivative analysis (TDA). Also the microstructure and mechanical properties were analyzed. Casting properties were determined by the castability spiral test. It was found that zinc is an essential component of the tested group of alloys, determining the course of their crystallization, phase composition and microstructure. There was no significant effect from the other elements on the course of crystallization. The obtained results revealed that bismuth is the element of the strongest impact on the castability changes. The formulated alloys surpass the commonly used standardized alloy intended for components of fittings, namely MO59, in terms of casting and mechanical (hardness) properties.
EN
In this work was shown a influence analysis foamed polystyrene model on casting defects as well as microstructure ductile cast iron from Lost Foam process with Inmold method.
11
Content available remote Heat transfer analysis during cooling of die with use of water mist
EN
The paper presents the results of the heat transfer area during the cooling process of steel test die with water mist which consist the flow of air in the range 150-350 l/min and 0.05 0.24 l/min of water. Temperature change in the thickness of die by means showing with the thermal curves and the temperature gradient and temperature distribution in the space between the nozzle and the cooled surface of the metal mold using a thermal imaging camera and thermocouples measurement. The course of changes in the temperature gradient and the received heat flux from the die while cooling its with the flow of air and water mist stream. It has been shown that the use of water mist with a variable flow of air and water controls the process of heat transfer process between the permanent molds, and a stream of water mist.
EN
The aim of this study was to investigate the effect of a two-step isothermal annealing respectively at 1000 ˚C for 30 min, then at the range of 900÷450 ˚C increments 50 ˚C on the microstructure CuAl10 Ni5Fe5 bronze with additions of Si, Cr, Mo, W and C, cast into sand moulds. The study concerned the newly developed species, bronze, aluminium-iron-nickel with additions of Si, Cr, Mo, W and C. In order to determine the time and temperature for the characteristic of phase transitions that occur during heat treatment of the test method was used thermal and derivation analysis (TDA). The study was conducted on cylindrical test castings cast in the mould of moulding sand. It was affirmed that one the method TDA can appoint characteristic for phase transformations points about co-ordinates: τ (s), t (˚C), and to plot out curves TTT for the studied bronze with their use. It was also found that there is a five isothermal annealing temperature ranges significantly altering the microstructure of examined bronze.
EN
The article presents the results of the research which was executed to describe the conditions specific of the formation of surface of certain micro-geometry and of the upper layers on precision titanium castings for medical industry. On the ready precision castings some tests were carried out to obtain the surface micro-geometry satisfying the requirements of implants to be used in human organism. The surfaces with specific spherical macro-unevenness were formed as well as plane surfaces of 2-6 [micro]m roughness. With the help of the light and electron microscopy, the possibility of formation of upper layers directly through an interaction of liquid titanium or Ti6Al4V alloy with the first layer of ceramic mould made from the ceramic mixtures based on Ekosil binder and molochite or zirconia has been confirmed.
14
Content available remote Hybrid foundry patterns of bevel gears
EN
Possibilities of making hybrid foundry patterns of bevel gears for investment casting process are presented. Rapid prototyping of gears with complex tooth forms is possible with the use of modern methods. One of such methods is the stereo-lithography, where a pattern is obtained as a result of resin curing with laser beam. Patterns of that type are applicable in precision casting. Removing of stereo-lithographic pattern from foundry mould requires use of high temperatures. Resin burning would generate significant amounts of harmful gases. In case of a solid stereo-lithographic pattern, the pressure created during gas burning may cause the mould to crack. A gas volume reduction may be achieved by using patterns of honeycomb structure. However, this technique causes a significant worsening of accuracy of stereo-lithographic patterns in respect of their dimensions and shape. In cooperation with WSK PZL Rzeszów, the Machine Design Department of Rzeszow University of Technology carried out research on the design of hybrid stereo-lithographic patterns. Hybrid pattern consists of a section made by stereo-lithographic process and a section made of casting wax. The latter material is used for stereo-lithographic pattern filling and for mould gating system. The hybrid pattern process consists of two stages: wax melting and then the burn-out of stereolithographic pattern. Use of hybrid patterns reduces the costs of production of stereolithographic patterns. High dimensional accuracy remains preserved in this process.
EN
Filtration guarantees castings characterised by high quality and free from any non-metallic inclusions, which are formed at the stage of melting and pouring of liquid metal. This article discusses the problem of the effectiveness of filtration process taking as an example heat-resistant cast steel poured into ceramic moulds. In investigations, foamed zircon filters made by FerroTerm Sp. z o.o. Łódź, Poland, were used. The effectiveness of filtration was described and examined using the results of metallographic examinations, including macro- and micro-structure examinations of metal and of cast metal/ceramic filter interface, and measurements of the content of non-metallic inclusions. The methods of investigations were presented, the obtained results were described, and relevant conclusions were drawn, all of them unmistakably indicating a very beneficial effect that filtration has on molten metal quality.
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