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MINISTRY OF EDUCATION AND TRAINING UNIVERSITY OF TRANSPORT AND COMMUNICATIONS -o0o - NGUYEN THUY CHI RESEARCH ON SCIENTIFIC BASIS TO DETERMINE REASONABLE TECHNICAL PARAMETERS OF BUCKET DRILLING MACHINES MADE IN VIETNAM Major: DYNAMIC MECHANICAL ENGINEERING Code: 9520116 SUMMARY ENGINEERING DOCTORAL THESIS Hanoi - 2021 Thesis completed at: Scientific supervisor: Assoc.Prof Dr Nguyen Dang Diem, Dr Nguyen Dinh Tu The thesis has been defended at the University-level Thesis Examination Committee, University of Transport and Communications At , date month year 20 This thesis may be learnt at: Library of University of Transport and Communications National Library of Vietnam INTRODUCTION Urgency of the thesis Currently, there are many different equipment used in the construction of foundations and foundations of construction works, including bored pile drilling machine Types of bored pile drilling machines being used in Vietnam are imported from abroad with expensive prices and the most difficult thing in "localization" the product is to manufacture the working set of the machine Starting from that, the production units are looking for ways to research and calculate the design of the machine's working set to replace imported equipment However, the content of the research is only stopping at the research and design of technology for machine manufacturing, without mentioning advanced research on the dynamics of the hydraulic transmission system and optimal design for bored pile drilling machine In addition, this is specialized equipment, so it is not easy, requiring basic research, scientific basis and especially technological knowhow in manufacturing suitable mechanical products with the current level of technology in our country Therefore, the topic "Research on scientific basis to determine reasonable technical parameters of bucket drilling machines made in Vietnam" is topical and highly urgent Objective of the thesis The research determines the reasonable technical parameters (structural and working parameters) of the bucket drilling machine made in Vietnam mounted on crawler cranes Based on the obtained research results, the thesis recommends some reasonable technical parameters of the machine in mining conditions in the Northern Delta Object and scope of research a) Research object: Bucket drilling machines made in Vietnam mounted on Hitachi CX500 crawler crane b) Research scope: Researching the dynamics of the hydraulic transmission system driving the work unit and determining the structural parameters and reasonable working parameters of the drill bucket with bore diameter Ф = 1.5 m, depth drill H = 70 m, working in the Northern Delta Research content - Overview of research issues - Research on hydraulic drive system dynamics of bucket drilling machine made in Vietnam - Research to determine structural parameters and reasonable working parameters of drill buckets - Experimental research to determine the dynamic parameters of the Hitachi CX500 bored pile drilling machine Scientific and practical significance of the thesis a Scientific significance: - Building a dynamic model of the hydraulic motor driving the drill plate and the dynamics of the hydraulic cylinder system of the drill plate of a rotary bucket-type bored pile drill mounted on a crawler crane in Vietnam corresponding to the following states: machine work - Building a simulation program of bored pile drilling machine in typical working cases, surveying the factors affecting the dynamic characteristics of the machine and then recommending reasonable technical parameters of the bored pile drilling machine from the point of view of dynamics - Building and solve the optimization problem according to the minimum specific energy cost criterion, thereby determining the reasonable structural and working parameters of the bucket b Practical significance: - The research results of the thesis can help manufacturers or operators of bored pile drilling machines as a reference in the design and manufacture of a working set of machines with high economic and technical criteria and use to select and operate equipment with reasonable working parameters New points of the thesis - Building and solving the dynamic model of the hydraulic motor driving the drill plate and the hydraulic cylinder pressing the drill plate on the bucket drilling machines during construction in the Northern Delta of Vietnam - Surveying the factors affecting the dynamic characteristics of the hydraulic transmission system of the machine and then recommending reasonable technical parameters (structural and working parameters) of the bucket drilling machines from the point of view of dynamics - Setting up and solving the optimization problem of structural parameters and working parameters of the bucket according to the minimum specific energy cost CHAPTER 1: OVERVIEW OF RESEARCH ISSUES 1.1 Introduction of Hitachi CX500 crawler crane mounted rotary bucket bored pile drill a General introduction The Hitachi CX500 crawler crane-mounted rotary bored pile drill is a drilling machine in which the rotating bucket-type operator is mounted on the base machine of Hitachi's crawler crane This is a drilling machine made in Japan in 1995, with a kelly rod-type drill rod, considered a high-yield device, able to drill from soft to hard geological strata such as sand, clay, gravel etc The biggest advantage is that it can drill holes up to 70 m deep, up to 2000 mm in diameter with a travel velocity of 1.7 km/h, providing high efficiency during construction The machine structure is quite simple, the user can easily control and operate it during the working process Although the initial investment cost for the machine is quite expensive, the work efficiency increases many times compared to other types of machines The machine's size is compact, moving and changing the working position is quick and convenient, in addition, it can also self-service lifting equipment and supplies during the working process Due to the crawler moving unit, large contact surface on the ground surface, the CX500 boring machine can move easily on soft ground, suitable for construction site terrain with many rough and sharp obstacles View according to A NHÌN THEO A A Figure 1.2 Bucket drilling machine mounted on Hitachi CX500 crawler crane 1- CX500 base machine; 2- Kelly bar; 3- Drill plate holder 4- Drill plate; 5- Drilling bucket b Introduction about the work set The work set of bucket drilling machine mounted on Hitachi CX500 crawler crane includes: ED12 drill head assembly (including: drill plate, drill drive motor, planetary reducer, drill plate feed cylinder, etc.), kelly rod and drill bucket PhD candidate selects the type of working bucket as a rotating bucket because the rotating bucket can be easily manufactured in the country, suitable for the technological conditions and skill level of our country's workers, in addition, it is possible to purchase other details or assemblies that cannot be manufactured domestically Currently, there are many types of standard rotating buckets, depending on the requirements and nature of the work, people choose different types of drill buckets with different diameters The rotating bucket has a structural feature that is different from other types in that at each point on the cutter edge, it performs a reciprocating motion in the direction of going deep into the ground and combining the rotational movement at the same time During the deformation and destruction of rock, the movement of the soil shavings is separated and slides on the top surface of the bucket teeth and accumulates in the bucket At the time of drilling, each point on the bucket teeth performs a reciprocating motion in the downward direction and a rotational motion The amount of longitudinal feed of the bucket during drilling will depend on the bucket pressure from the top as well as the compressive strength of the rock, [34], [36] The torque from the drill rod transmitted to the bucket causes the bucket to rotate Structure of the rotating bucket is as shown in Figure 1.4 below: According to A Figure 1.4 Structure of rotating bucket of bored pile drilling machine 1- Positioning nose; 2- Bucket wall; 3- Bucket bottom open handle; 4- End on drill bucket; 5- Top of drill bucket; 6- Strengthening tendon; 7- Bucket bottom hinge; 8- Bucket teeth 1.2 Overview of research works at home and abroad related to the thesis 1.2.1 Overview of studies on the dynamics of bored pile drilling machines There have been many works by scientists in China, Vietnam and other countries researching the dynamics of bored pile drilling machines, which have been presented in the documents [47], [63], [67] From these studies, it can be seen that, the works mainly focus on the research on the dynamics of the guide ring as well as the simulation of the dynamics of the guide rack structure of the bored pile drill while the dynamics The hydraulic drive system of the machine is not taken into account 1.2.2 Overview of research works on structural optimization analysis of bored pile drilling machines In the world and in the country, there have been many research works on the analysis and optimization of the structure of bored pile drilling machines shown in the documents [19], [35], [60], 62, [66] ] Through these studies, it can be seen that the authors have focused on the following issues and some of the following still exist: - Optimization of equipment's fuel costs, optimization of structural and working parameters of the equipment has not been mentioned - Optimizing the steel structure of the box boom and the winch installation position, the optimization of the drilling bucket parameters has not been performed - Determining the reasonable operating parameters of the bored pile drilling machine whose working set is the bottom expansion bucket but not the vertical cylindrical rotary drilling bucket Optimizing the operating parameters according to the criterion of maximum bottom expansion yield, not to mention the minimum specific energy criterion The optimization of the structural parameters of the bucket is also not considered - Optimization of working parameters of bottom expansion bucket with geology in Ho Chi Minh City is different from the type of swing bucket and soil properties of the Northern Delta that the thesis refers to 1.2.3 Overview of research projects on design and manufacture of bored pile drilling machines in Vietnam Research works on design and manufacture of bored pile drilling machines in Vietnam focus on documents [4], [5], [47] Objective of [4] is to solve the urgent requirement of localizing the BG36 bored pile drill head assembly The author [4] proposed the required capacity when drilling, this is also the premise for the domestic manufacture of BG36 drill buckets to replace imported equipment The author [47] focuses on researching, designing and manufacturing drilling work sets in the country Therefore, the research and solving optimization problems to find a reasonable set of drilling bucket parameters have not been mentioned The author [5] has researched, designed, and manufactured a two-motor drive rotary wheel to replace a single-motor drive wheel for bored pile drilling machines This is a research topic that only serves the manufacture of rotary wheels, not a research on the theoretical basis for manufacturing the entire working set of domestic bored pile drilling machines to replace imported equipment Conclusion of Chapter and research orientation The overview research on the works of domestic and foreign authors on the dynamics of bored pile drilling machines, optimization of bucket design as well as research on design and manufacture of drilling buckets in the country in Chapter shows that : In terms of dynamics, the above works mainly introduce methods of calculating machine learning or kinematics of the drill rod, however, the dynamics of the hydraulic transmission system of the machine takes into account the influence of the building foundation has not been mentioned much In terms of analysis and optimization of the structure of the bored pile drilling machine, the author mainly optimizes the fuel cost, the steel structure of the drill rod, the location of the winch installation , and the optimization of the structural and working parameters of the bucket has not been performed In addition, the determination of the operating parameters of the bored pile drilling machine is mainly done with the bottom expansion bucket, and the cylindrical rotary drilling bucket, including the geology of the Northern Delta, has not been exploited yet In terms of design and manufacturing of bored pile drilling machines in Vietnam, the main works are research and design technology for machine manufacturing and improvement of drilling technology, while solving the optimal problem to find the reasonable set of parameters of the drill bucket in the mining conditions in Vietnam has not been mentioned On the basis of a general overview of the issues related to the thesis, the content of the next chapters can be determined as follows: Research on the dynamics of the hydraulic transmission system on the machine takes into account the influence of geological conditions and the foundation of the building From there, the reasonable specifications of the working set are proposed from the dynamic point of view The research provides computational models to determine the resistance force, the resisting moment acting on the workpiece during the drilling machine working, taking into account the influence of Vietnam's geological conditions From there, research and calculate to determine the required power to drive the motor to rotate the drill Building and solve optimization problems to determine the reasonable specifications of the bucket Experimental research on bucket drilling machine mounted on Hitachi CX500 crawler crane made in Vietnam CHAPTER 2: RESEARCH ON THE DYNAMICS OF THE HYDRAULIC DRIVE SYSTEM OF BUCKET DRILLING MACHINES MADE IN VIETNAM 2.1 Research on the dynamics of the hydraulic transmission system driving the hydraulic motor to rotate the drill plate Mc Mc1 Qd1 Jm1 pa Mqt1 Mc2 nd1 Qd2 rd1 Mqt2 nd2 rd2 Jm2 Vd1 Vd2 Ea Qd pc pc pa Qb Qat A B P T Qb1,Vb1 Qb2,Vb2 M pat n b1 pt n r b2 r b1 b2 Figure 2.2 Dynamic model of the hydraulic transmission system driving the hydraulic motor to rotate the drill plate Where: Vb1, Vd1: Specific flow of pump and hydraulic motor 1, m3/rev; Vb2, Vd2: Specific flow of hydraulic pump and motor 2, m3/rev; nb1, nd1 : Number of revolutions of pump shaft and motor 1, rev/s; nb2, nd2 : Number of revolutions of pump shaft and motor 2, rev/s; pa: Pressure of the working oil in the high pressure branch of the engine, Pa; pt: Pressure of the working oil in the low pressure branch of the engine, Pa; pat: Set pressure of safety valve, Pa; rb1 , rd1 : Coefficient of flow loss in hydraulic pump and hydraulic motor 1, (m 3/s)/Pa; rb2 , rd2 : Coefficient of flow loss in hydraulic pump and hydraulic motor 2, (m3/s)/Pa; Ea: Elastic deformation in high-pressure pipeline, m3/Pa; Qb: Total flow of pumps, m3/s; Qb1: Flow of pump No 1, m3/s; Qb2 : Flow of pump No 2, m3/s; Qd: Total required flow through motors, m3/s; Qd1: Flow of motor 1; m3/s; Qd2: Flow of motor 2; m3/s; Qat : Oil flow through safety valve, m3/s; Mqt1: Moment of inertia of hydraulic motor 1, N.m; Mqt2: Moment of inertia of hydraulic motor 2, N.m; Mc: Torque resisting rotation on the bucket, N.m Mc1: Torque resisting rotation on the shaft of hydraulic motor 1, N.m; M c2: Torque resisting rotation on the shaft of hydraulic motor 2, N.m Through setting up the flow equation and force balance, the following system of differential equations is obtained: Ea dpa dt Vb1 [nb1 ].(1−ηb1 ) V [n ].(1−ηd1 ) pa − Vd1 nd1 − d1 d1 pa [pb1 ] [pd1 ] pa Vd1 [pd1 ].(1−ηc1 ηh1 ηd1 ) Vd1 − n − M d1 c1 2π 2π.[n ] = Vb1 nb1 X(t) − (pa − pc ) K c − Jm1 dnd1 dt = − (pa − pat ) K at d1 Angular velocity of the hydraulic motor driving the drill plate, rad/s Time (s) Total power of the hydraulic motor driving the drill plate, kW Figure 2.6 Oil pressure in the high pressure chamber of the hydraulic motor driving the drill plate Time (s) Figure 2.7 Angular velocity of the hydraulic motor driving the drill plate Time (s) Figure 2.9 Total flow of oil supplied to the hydraulic motor driving the drill plate, l/min Number of revolutions of drill plate, revolution/min Figure 2.8 Total power of the hydraulic motor driving the drill plate Time (s) Total flow of oil supplied to the hydraulic motor driving the drill plate, l/min Oil pressure in the high pressure chamber of the hydraulic motor driving the drill plate, Pa (2.16) Graphs are the results of solving the system of equations (2.16) as follows: Time (s) Figure 2.10 Number of revolutions of drill plate Torque on hydraulic motor shaft, N.m 11 Time (s) Figure 2.25 Torque on hydraulic motor shaft for different geological strata 2.3.2 Surveying the parameters affecting the dynamic parameters of the hydraulic cylinder pressing the drill plate With the Matlab Simulink program built in Figure 2.13, other input parameters are considered unchanged according to Table 2.2 in the explanation, conduct a survey when changing the diameter of the drill press cylinder (D = 100 mm; D = 110 mm; D = 130 mm) and change the resistance acting on the drill press cylinder (Fc = 16000 N; Fc = 22000 N; Fc = 26000 N), the results are shown as the following figures: x104 Oil pressure in cylinder presses drill plate, Pa Drill plate force, N x105 Time (s) Time (s) Figure 2.37 Drill plate force presses drill plate when changing cylinder diameter changes as the cylinder diameter changes Pressing velocity of drill plate, m/s Figure 2.36 Oil pressure in cylinder Time (s) Figure 2.38 Pressing velocity of drill plate when cylinder diameter changes Fc=1.6 ton Fc=2.2 ton Fc=2.6 ton Time (s) Figure 2.39 Oil pressure in the cylinder presses the drill plate when changing the resistance applied to the cylinder Fc=1.6 ton Fc=2.2 ton Fc=2.6 ton Drill plate force, N Oil pressure in cylinder presses drill plate, Pa 12 Time (s) Figure 2.40 Drilling plate pressure when changing the resistance acting on the cylinder Conclusion of Chapter A dynamic model of the hydraulic transmission system of the hydraulic motor rotates the drill plate and the dynamic model of the hydraulic transmission system of the drill press cylinder has been built Calculation results show that the change of dynamic parameters in the working stages of the machine corresponds to the brown-gray clay layer in the soft plastic state, specifically as follows: - Oil pressure supplied to the hydraulic motor and the number of revolutions of the drill plate reached the maximum value when starting at 80.105 Pa and 17.4 rpm, respectively - When starting the hydraulic cylinder to press the drill bucket, the oil pressure and the thrust of the cylinder both change with time and after a short time reach a definite value when working stably is 16.10 Pa and 1,63 104 N Change of the oil pressure and the thrust of the cylinder depends on the change of resistance acting on the bucket - Velocity fluctuations with a large amplitude at the start-up stage cause dynamic loads on the steel structure of the equipment There should be solutions to reduce this change such as using throttling in the hydraulic circuit of the device to minimize the harmful effects of dynamic forces Influence of geological strata (soil level), elastic deformation Ea, efficiency of pump (b), diameter of drill press cylinder (D) as well as resistance force on cylinder has been investigated pressing cylinder (Fc) to the machine's hydraulic drive system dynamics parameters The survey results show that the amplitude of fluctuation of pressure and flow supplied to the hydraulic motor as well as the number of revolutions of the drill plate in the hard, gravelly, and gravelly geological strata is larger than that of soft clay strata For each soil level, a specific value of the number of revolutions of the drill plate and the cylinder feed velocity can be found The determination of these two 13 parameters is of great significance, this is the scientific basis for constructing and solving the optimization problem of Chapter CHAPTER 3: RESEARCH FOR DETERMINATION OF STRUCTURAL PARAMETERS AND REASONABLE WORKING PARAMETERS OF DRILL BUCKET The optimal problem model is stated as follows: “With a given ground topography and a designed borehole with parameters including bore diameter Dl, drilling depth H, it is necessary to determine the optimal structural parameters of the drill bucket, which is the cutting angle δ of the cutting edge, the optimal working parameter is the angular velocity ω of the bucket and the feed velocity of the drill press cylinder v xl on the basis that the specific energy cost E for the hole drilling process is minimal with the conditions to ensure a given drilling capacity Q0 ” Specific energy E of the equipment is equal to the total cost power for duty cycle of the equipment for unit of productivity, [68]: E N kWh/m3 , Q (3.1) Where: N: Total cost power for a machine duty cycle, kW; Q: Average theoretical productivity of bored pile drilling machine, m3/h 3.1 Determining the Q of the device Q 3600.Vđ TCK 3600..R Hg TCK , m3/h (3.5) With R: radius of drill bucket, m; Hg: height of the drill bucket, m; Tck: Time of duty cycle, s 3.2 Determining the power N of the device Call N as total cost power for working cycle of the machine, the component powers are determined as follows: N= N1+ N2+ N3+ N4+ N5, kW (3.6) Capacity of cutting and soil load in bucket N is determined as follows: N1 M. , kW (3.7) 1000 With ∑ M: Total resistance moment when shearing and loading the soil into the bucket, N.m; ω: Angular velocity of bucket, rad/s 14 Capacity of pulling the bucket out of the borehole N2 is determined as follows: P v N K K , kW (3.18) 1000 Where PK: Pulling force of the impeller out of the borehole, N; vK : Velocity of pulling the bucket out of the borehole (by lifting cable), m/s Capacity to rotate the bucket from the borehole to the dump position N3 is determined by calculating the rotational resistance as calculated for the crawler crane M q q (3.19) N3 , kW 1000 Where Mq : Total rotational resistance of the machine, N.m; ωq: Angular velocity when rotating the camera, rad/s Capacity of rotating the bucket from the pouring position back to the borehole N4 is determined as follows: M qo q (3.20) N4 , kW 1000 Where Mqo is the rotation resistance torque when the soil has been poured from the bucket (Gd = 0), N.m; Capacity when pressing hydraulic cylinders of N5 drill plate pressing cylinders during machine working: N5 pXL vXL kW , 1000 (3.21) With pxl: the pressure of hydraulic cylinders, N; v xl: Feeding velocity of hydraulic cylinders when pressing, m/s So we have the formula to determine the specific energy for duty cycle of the device as follows: E 2 N.TCK TCK sin( ) .R Hg Fao K.R tg tg tg sin cos 3600.Vđ 3600..R Hg 1000 l. cos Mq q Mqo q pXL v XL b d Pv R4 c1.2 2R1.K.B.C2 R.Fao f V. v K K ,(kWh / m ) g 1000 1000 1000 1000 (3.22) Remark: From the formula (3.22) above it may be seen: Total capacity and component capacities depend on the structural parameters of the bucket such as bucket radius R, bucket height Hg These two parameters can be determined based on the requirements of the hole diameter and depth to be drilled The cutting angle of the cutter (related to the chip thickness), depends on the working parameters of the device such as the angular 15 velocity of the drill bucket ω and the feed velocity of the hydraulic cylinders pressing the drill plate vXL In addition, the specific energy E also depends on the mechanical and mechanical properties of the construction ground such as the soil level of the foundation determined by the pure shear coefficient K, soil density ρ Specific energy E also depends on other parameters of the impeller and the base machine through the components of the machine's rotational resistance and the frictional torque in the drill plate bearing assembly Thus, with a known soil type when assigned for construction, through drilling and exploration, we have a geotechnical map of the work according to the depth of the borehole, and the required parameters of the hole are obtained such as hole diameter and drilling depth from there allow the diameter and height of the bucket to be determined in advance According to the above analysis, the specific energy cost E depends on many parameters, of which the structural and working parameters of the bucket have a direct influence on the value of E Therefore, from the problem built above, the objective function of the problem is to determine the structural and working parameters of the bored pile drill bucket according to the specific energy cost criterion which can be stated as after: “When the specific energy cost function E is written in the form E=f(x i) with xiRn is the structural parameters of the drill bucket ( x1= ) and working parameter (x2= ; x3=Vxl) Find the minimum value (min) of the function f(x i) corresponding to xiRn and satisfy the condition of bore diameter Dl and the constraints: L
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