Industrialization of Aluminum Alloy Uniform Solidification Controlled Rheological Die Casting

An efficient and low-cost aluminum alloy uniform solidification control technology, namely, air-cooled stirring rod (ACSR) process, has been developed for preparing large volume semisolid slurry. The semisolid slurry preparation process is connected with the die-casting machine to form multiple integrated intelligent rheological die-casting production lines for the efficient preparation of rheological die-casting of large-scale thin-walled aluminum alloys. At present, the ACSR process can produce 40 kg of large-volume semisolid slurry with a solid phase ratio of 25% to 35% within 30 s. This rheological die-casting process has been industrialized for the preparation of high-quality aluminum alloy large-scale thin-walled parts, such as new energy vehicles and 5G communications. Typical products produced by this process include heat dissipation housings for 5G communications, filter housings, antenna chassis and three-electric structural shell, end cover, and ABS system valve body for new energy vehicles. Compared with traditional die castings, aluminum alloy castings prepared by the new process not only have fine and spherical microstructures, good surface quality, and fewer internal pores but also enjoys more excellent mechanical properties and thermal conductivity.

Strength and Service Life of a Steam Turbine Stop and Control Valve Body

The stability of operation of steam turbines depends (along with other factors) on the reliable operation of their steam distribution systems, which are based on stop and control valves. This paper considers the strength of the elements of the K-325-23.5 steam turbine valves, in whose bodies, after 30 thousand hours of operation, cracks came to be observed. Previously determined were the nature of gas-dynamic processes in the flow paths of the valves and the temperature state of the valve body in the main stationary modes of operation. To do this, a combined problem of steam flow and thermal conductivity in stop and control valves was solved in a three-dimensional formulation by the finite element method. Different positions of the valve elements were considered taking into account the filter sieve. The assessment of the thermal stress state of the valve body showed that the maximum stresses in different operating modes do not exceed the yield strength. Therefore, the assessment of the creep of the valve body material is important to determine the valve body damage and service life. Modeling the creep of the stop and control valves of the turbine was performed on the basis of three-dimensional models, using the theory of hardening, with the components of unstable and steady creep strains taken into account. The creep was determined at the maximum power of the turbine for all the stationary operating modes. The maximum calculated values of creep strains are concentrated in the valve body branch pipes before the control valves and in the steam inlet chamber, where in practice fatigue defects are observed. However, even for 300 thousand hours of operation of the turbine (with a conditional maximum power) in stationary modes, creep strains do not exceed admissible values. The damage and service life of the valve bodies were assessed by two methods developed at A. Pidhornyi Institute of Mechanical Engineering Problems of the NAS of Ukraine (2011), and I. Polzunov Scientific and Design Association on Research and Design of Power Equipment. (NPO CKTI) – 1986. The results of assessing the damage and the turbine valve body wear from the effects of cyclic loading and creep of the turbine in stationary modes for 40, 200 and 300 thousand hours show that the thermal conditions of the body in the steam inlet chamber are not violated (without taking into account possible body defects after manufacture). The damage in valve body branch pipes after 300 thousand hours of operation exceeds the admissible value, with account taken of the safety margin. At the same time, the damage from creep in stationary operating modes is about 70% of the total damage. The maximum values of damage are observed in the areas of the body where there are defects during the operation of the turbine steam distribution system. The difference between the results of both methods in relation to their average value is ~20%.

Investigation of a Digital Hydraulic Valve Operated by Servo Motors

This paper describes a new type of digital hydraulic valve run by two servo motors. Digital hydraulics is a cutting-edge technology, which saves more exhausted energy than conventional hydraulic valves. It includes conventional valves, but its working principle is different. Similar or different size valves constitute a digital hydraulic valve assembly. When the assigned valves are opened, a certain amount of flow is obtained from the output of the valve assembly. To control a digital hydraulic valve, Pulse Number Modulation (PNM) Control technique is used for equal valve flow rates, while Pulse Code Modulation (PCM) is used for different valve flow rates. Valves are exerted by independently launched electric coils. Previous studies used controller board and external power booster circuits for coils. In this study, a new type of digital hydraulic valve is designed, manufactured, and tested with the PNM method. The studied valve body has two different valve groups. Every group includes 16 equal valves and 1 camshaft rotated by 1 servo motor. The servo motors are controlled by a PLC. The calculated performance index is found to be 5.1ms which is similar to the results of previous studies. The experimental results showed that the cam and servo motor controlled digital hydraulics is applicable to variable speed control hydraulic systems.

Computational design optimization of industrial single piece ball valve to enhance the flow performance

The characteristics of flow through the fluid flow system largely depends on the control valves and their performance. Ball valves are one among the major valves widely used in various industries due to their simple construction and ease of manufacturing. Thus investigating flow characteristics of these valves is most essential to minimize the losses due to friction and cavitation caused within the valve body. The main objective of the current work is to carry out the computational fluid dynamics analysis using Ansys® Fluent® as solver and Solidworks® as 3D modelling tools to investigate the flow patterns through the single piece ball valve to determine the various flow characteristic and there by suggest design optimization for improved flow rate and performance. Various designs of ball valve such as BVD1, BVD2 and BVD3 were tested through CFD simulation. The simulation results reveals that BVD1 and BVD2 are failed in bidirectional flow characteristics. However BVD3 shows the significant improvement in all the flow characteristics.

Characterization of Solenoid On-Off Valve Faults: A Faster Analytical Modeling Approach

Solenoid valves are enabling components for flow and motion control in fluid power systems. It is important for reduction of a machinery’s “off” time if quick fault diagnosis of solenoid valves can be performed on site. Traditional fault diagnosis usually involves signal convolution, machine learning, or fuzzy logics, which can achieve over 90% accuracy but are all computationally intensive, and may be difficult to achieve rapid analysis on site with portable electronics. Among various kinds of faults of solenoid valves, the most common ones are the leakage caused by poor sealing between the poppet and the sleeve, stiction caused by foreign matters in the valve body, or solenoid failure. This paper proposed to simplify the fault diagnosis process by derivation of analytical models of fault characteristics of solenoid on-off valve based on electromagnetics and lumped mass fluid mechanics. Firstly, according to the structure of the solenoid valve, the electromagnetic model of the armature, solenoid, and the air gap is deduced. Secondly, five features from two sensor data are constructed. Fault isolation matrix, tested features are also defined. Thirdly, experimental system was setup to acquire the key threshold values for membership function definition. Finally, two validation tests were conducted and the initial results showed that the proposed method is capable of detecting solenoid valve stiction of various degrees.

Riddance jamming of pipeline shut-off valves

The paper conciders the problems of modeling the processes of thermal deformation of valves with an ambient temperature decrease. Some type of wedge valves are exposed to jamming. Heating the valve body is used to eliminate jamming. This problem is common for rigid wedge valves but the reasons not fully explained. Sometimes the valve stem is destroyed due to the significant power of the gate valve electric drives. The aim of the study is to determine the nature of the stress distribution between the structural elements of the valve, which are the cause of jamming with an ambient temperature decrease, and to search for the parameters of the heating process that ensure minimum energy consumption and time. To study the thermal processes in the valve body, a numerical model describing the heat transfer in the structural elements and the fluid is developed. The thermal model is combined with the elastic deformation model. That allows to make compatible calculations without introducing additional errors. The thermal deformations appear in the cooling process and give rise to disproportionate changes in valve dimensions and thermal stresses. Thermal stresses are the cause of jamming. Modeling of the processes of thermal deformation with a decrease in temperature showed that pressure forces of different signs arise in the middle plane of the wedge. At the average height of the horizontal line, there is a compacting pressure and at the lower and upper points there is a stretching pressure. To eliminate the compacting forces local heating was performed in several areas of the body. It was found that the most effective option is to heat the lower hemispherical surface of the body. Heating for thirty minutes reduces the thermal stresses in the wedge and compressive forces to minimum values. For this reason, jamming of the valve is eliminated. For heating the body, a hemispherical induction heater with a magnetic core is provided. The proposed design allows the use of industrial frequency voltage without a step-down transformer and reactive power compensation.

The control optimization algorithm for automatic braking of a wheeled vehicle

Introduction (problem statement and relevance). One of the most promising and intensively developing directions in the automation field of road transport management is the creation of highly automated vehicles.The purpose of the study was to find a way to solve a wheeled vehicle safe automatic braking problem in terms of minimizing quality control of the quadratic functional and work out optimal software and hardware implementation of this system.Methodology and research methods. To solve the problem, the method of the control algorithm analytical design was used, basing on the use of the necessary conditions for minimizing the elements of the functional for the control law synthesis. The maximum deceleration value was due to the identified tire grip, and the deceleration threshold from which braking begins was selected as the minimum of the working deceleration and two decelerations depending on the rear obstacle distance.Scientific novelty and results. The tests of the developed function were carried out for the LADA Vesta vehicle equipped with an ABS valve body with the possibility of programmed control. The analysis of the research results showed that when solving the problem of safe automatic braking in front of an obstacle, the software limitation of braking deceleration did not allow wheel blocking and performed the functions of an anti-lock braking system at the permissible wheel slipping level; software backup of the distance calculation to the front obstacle from the moment of braking start allowed to prevent most of the situations with false data from the radar when the vehicle pecked during braking.Practical significance. Software tuning of mathematical models parameters of the engine, transmission and braking system allows you to adapt the automatic braking system to a wide class of vehicle models.

RESULTS OF THE APPLICATION OF NEW TECHNOLOGIES IN INCREASING RESOURCES IN HIGH PRESSURE DRILLS

In oilfield practice, as well as in the transportation of oil and gas, great importance is attached to the use of high-pressure valves. Since the demand for this fleet of equipment is growing, it is especially important to increase their resources and reduce their cost on this basis. Along with the constructive and technical measures taken in this direction, serious attention should be paid to improving the choice of materials for the manufacture of parts and their production technology.. The article is devoted to the discussion of the results obtained when using the coquille technology for the manufacture of parts made of low-alloy chromium-molybdenum steel Keywords: high-pressure gate valve, body, gate, seat, hardness, wear.

Risk Assessment and Material Suitability Evaluation on Static Equipment of Hydrofluoric Acid Alkylation Unit

In 2005, a 60 kt/a alkylation (ALK) unit began to resume production in the Second Oil Refinery Plant of Beijing Yanshan Petrochemical Company. There have been many leak cases from pipeline welds, valve body, flange, etc. After a half-year period of operation, production process is stable. However, the operation of the hydrofluoric (HF) acid ALK unit has been suffered from corrosion problems. There are no clear answers and references to the following problems. What types of corrosion are currently in the main equipment for HF acid ALK unit? What does cause equipment corrosion? What are the main influencing factors for corrosion? What measures can be taken to reduce the corrosion of HF acid? In this paper, considering the acid-related conditions of the ALK unit, the damage mechanism and damage rate analysis were carried out to calculate the safety risk of the static equipment of the ALK unit. Based on the damage mechanism and failure history, the material suitability of the ALK unit was investigated. The anti-corrosion measures and recommended materials for important corrosion parts of the ALK unit were proposed. It is meaningful for reducing the number of shutdowns of ALK units and maintaining safe and stable operation of the unit.