Further development of the technology for making moulding and core sands will be strictly limited by tough requirements due to protection of the natural environment. These tendencies are becoming more and more tense, ...Further development of the technology for making moulding and core sands will be strictly limited by tough requirements due to protection of the natural environment. These tendencies are becoming more and more tense, so that we will reach a point when even processes, that from technological point of view fulfill high requirements of the foundry industry, must be replaced by more ecologically-friendly solutions. Hence, technologies using synthetic resins as binding materials will be limited. This paper presents some predictable development tendencies of moulding and core sands. The increasing role of inorganic substances will be noticed, including silicate binders with significantly improved properties, such as improved knock-out property or higher reclamation strength. Other interesting solutions might also be moulding sands bonded by geo-polymers and phosphate binders or salts and also binders based on degradable biopolymers. These tendencies and the usefulness of these binders are put forward in this paper.展开更多
The protein based binding material is from natural products, which is nontoxic and recyclable. This kind of green binder is earnestly needed by aluminum casting products. The new protein based core possesses higher st...The protein based binding material is from natural products, which is nontoxic and recyclable. This kind of green binder is earnestly needed by aluminum casting products. The new protein based core possesses higher strength and easier shakeout. Its tensile strength is close to that of common resin sands. The micro mechanism of protein binder was investigated by using infrared spectrum, chemical element analysis, SEM and thermal lost mass analysis.展开更多
The influence of core sand properties on flow dynamics was investigated synchronously with various core sands, transparent core-box and high-speed camera. To confirm whether the core shooting process has significant t...The influence of core sand properties on flow dynamics was investigated synchronously with various core sands, transparent core-box and high-speed camera. To confirm whether the core shooting process has significant turbulence, the flow pattern of sand particles in the shooting head and core box was reproduced with colored core sands. By incorporating the kinetic theory of granular flow(KTGF), kinetic-frictional constitutive correlation and turbulence model, a two-fluid model(TFM) was established to study the flow dynamics of the core shooting process. Two-fluid model(TFM) simulations were then performed and a areasonable agreement was achieved between the simulation and experimental results. Based on the experimental and simulation results, the effects of turbulence, sand density, sand diameter and binder ratio were analyzed in terms of filling process, sand volume fraction(αs) and sand velocity(Vs).展开更多
Mechanical reclamation processes of spent moulding sands generate large amounts of postreclamation dusts mainly containing rubbed spent binding agents and quartz dusts. The amount of postreclamation dusts, depending i...Mechanical reclamation processes of spent moulding sands generate large amounts of postreclamation dusts mainly containing rubbed spent binding agents and quartz dusts. The amount of postreclamation dusts, depending in the reclamation system effi ciency and the reclaim dedusting system, can reach 5%-10% in relation to the total reclaimed spent moulding sand. The proper utilization of such material is a big problem facing foundries these days. This study presents the results of investigations of physicochemical properties of post- reclamation dusts. All tested dusts originated from various Polish cast steel plants applying the mechanical reclamation process of moulding sands with alkaline resins, obtained from different producers. Different dusts, delivered from foundries, were tested to determine their chemical composition, granular characterization, physicochemical and energetic properties. Presented results confi rmed assumptions that it is possible to utilize dusts generated during mechanical reclamation of used sands with organic resins as a source of energy.展开更多
When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase.The design of permanent cores is hig...When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase.The design of permanent cores is highly restricted in order to maintain removability.Lost cores provide the possibility of complex,undercut geometrical shapes which is mandatory for a variety of casting components.However,eligible materials which show appropriate resilience and proper decomposition properties at the same time,and in the upper echelon of cost-effectiveness,are seldom known.With the semi-solid process suited between HPDC and GDC regarding the core stress,several common and economically efficient lost core systems could be used.A selection of potentially suitable materials was identified and tested.The range of testing comprises widespread sand core-systems(amin-pur-coldbox and CO2-water-glass) as well as materials less commonly used,namely salt,plastic and zinc.Different types of conditioning are applied to enhance the surface properties.The mechanical properties of the sand cores are enhanced by different heat treatment methods during curing.The cores are tested producing a research component cast on a HPDC machine with semi-solid A356 slurry fabricated in the cooling channel process.The cast component was analyzed regarding shape stability,core removability and surface as well as the structure quality.The results show the importance of the surface conditioning for the sand-cores while salt and zinc produce good parts comparable to the reference steel core quality.展开更多
This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens...This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens were heat treated to obtain hardness of 294, 445 and 595 HV200 (29, 45 and 55 HRC). Erosion tests were carried out at impingement angles from 20° to 90° and air drag pressures of 1.38, 2.07 and 2.76 bar (20, 30 and 40 psi). The main results are summarized as follows:(i) The harder material, the lower erosion;(ii) the maximum erosion rate is at 30°;(iii) Little difference in erosion rate at impact angle of 60° and 90° for a constant pressure tested regardless of the hardness level;(iv) As the pressure increases, so does the erosion rate, being more sensitive for low impact angles. Finally, a differential form of the general erosion equation is applied on a practical core-making case to evaluate the erosion rate of the H13 steel at 30° and 90° impingement angles.展开更多
文摘Further development of the technology for making moulding and core sands will be strictly limited by tough requirements due to protection of the natural environment. These tendencies are becoming more and more tense, so that we will reach a point when even processes, that from technological point of view fulfill high requirements of the foundry industry, must be replaced by more ecologically-friendly solutions. Hence, technologies using synthetic resins as binding materials will be limited. This paper presents some predictable development tendencies of moulding and core sands. The increasing role of inorganic substances will be noticed, including silicate binders with significantly improved properties, such as improved knock-out property or higher reclamation strength. Other interesting solutions might also be moulding sands bonded by geo-polymers and phosphate binders or salts and also binders based on degradable biopolymers. These tendencies and the usefulness of these binders are put forward in this paper.
文摘The protein based binding material is from natural products, which is nontoxic and recyclable. This kind of green binder is earnestly needed by aluminum casting products. The new protein based core possesses higher strength and easier shakeout. Its tensile strength is close to that of common resin sands. The micro mechanism of protein binder was investigated by using infrared spectrum, chemical element analysis, SEM and thermal lost mass analysis.
基金supported by the National Science Foundation of China(Grant Number 51575304)the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant Number 2012ZX04012011)
文摘The influence of core sand properties on flow dynamics was investigated synchronously with various core sands, transparent core-box and high-speed camera. To confirm whether the core shooting process has significant turbulence, the flow pattern of sand particles in the shooting head and core box was reproduced with colored core sands. By incorporating the kinetic theory of granular flow(KTGF), kinetic-frictional constitutive correlation and turbulence model, a two-fluid model(TFM) was established to study the flow dynamics of the core shooting process. Two-fluid model(TFM) simulations were then performed and a areasonable agreement was achieved between the simulation and experimental results. Based on the experimental and simulation results, the effects of turbulence, sand density, sand diameter and binder ratio were analyzed in terms of filling process, sand volume fraction(αs) and sand velocity(Vs).
基金financed by The Polish National Centre for Research and Development within the project INNOTECH-K1/IN1/57/156360/NCBR/12
文摘Mechanical reclamation processes of spent moulding sands generate large amounts of postreclamation dusts mainly containing rubbed spent binding agents and quartz dusts. The amount of postreclamation dusts, depending in the reclamation system effi ciency and the reclaim dedusting system, can reach 5%-10% in relation to the total reclaimed spent moulding sand. The proper utilization of such material is a big problem facing foundries these days. This study presents the results of investigations of physicochemical properties of post- reclamation dusts. All tested dusts originated from various Polish cast steel plants applying the mechanical reclamation process of moulding sands with alkaline resins, obtained from different producers. Different dusts, delivered from foundries, were tested to determine their chemical composition, granular characterization, physicochemical and energetic properties. Presented results confi rmed assumptions that it is possible to utilize dusts generated during mechanical reclamation of used sands with organic resins as a source of energy.
文摘When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase.The design of permanent cores is highly restricted in order to maintain removability.Lost cores provide the possibility of complex,undercut geometrical shapes which is mandatory for a variety of casting components.However,eligible materials which show appropriate resilience and proper decomposition properties at the same time,and in the upper echelon of cost-effectiveness,are seldom known.With the semi-solid process suited between HPDC and GDC regarding the core stress,several common and economically efficient lost core systems could be used.A selection of potentially suitable materials was identified and tested.The range of testing comprises widespread sand core-systems(amin-pur-coldbox and CO2-water-glass) as well as materials less commonly used,namely salt,plastic and zinc.Different types of conditioning are applied to enhance the surface properties.The mechanical properties of the sand cores are enhanced by different heat treatment methods during curing.The cores are tested producing a research component cast on a HPDC machine with semi-solid A356 slurry fabricated in the cooling channel process.The cast component was analyzed regarding shape stability,core removability and surface as well as the structure quality.The results show the importance of the surface conditioning for the sand-cores while salt and zinc produce good parts comparable to the reference steel core quality.
基金financially supported by NEMAK S.A. and Industria Meccanica Bassi Luigi&Co
文摘This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens were heat treated to obtain hardness of 294, 445 and 595 HV200 (29, 45 and 55 HRC). Erosion tests were carried out at impingement angles from 20° to 90° and air drag pressures of 1.38, 2.07 and 2.76 bar (20, 30 and 40 psi). The main results are summarized as follows:(i) The harder material, the lower erosion;(ii) the maximum erosion rate is at 30°;(iii) Little difference in erosion rate at impact angle of 60° and 90° for a constant pressure tested regardless of the hardness level;(iv) As the pressure increases, so does the erosion rate, being more sensitive for low impact angles. Finally, a differential form of the general erosion equation is applied on a practical core-making case to evaluate the erosion rate of the H13 steel at 30° and 90° impingement angles.
