E-book details

Laboratory of Construction Machinery

Laboratory of Construction Machinery

Paweł Ciężkowski

Ebook

In this script, the laboratory exercises presented are divided into two groups. In the fi rst group, the authors describe the stands and test methods to determine the basic strength parameters of soils and rocks. The stands discussed allow students to become familiar with model processes of interaction of construction machinery tools with geomaterials and road surface materials (asphalt, concrete). The model investigations are concerned with elementary rock fragmentation processes and the interaction of crushing tools in the milling process of road surfaces. Exercises on machine-based crushing processes will be presented. Within this group of exercises, students will become familiar with the construction and operation of various types of crushers (cone, impact, jaw). The exercises will include studies of: a) the influence of the type of crusher on the shape and grain size of the product obtained, b) the influence of the outlet gap setting on the forces, energy consump-tion and effi ciency of the crushing process, c) the infl uence of the shape of jaw crusher crushing plates on the parameters of the crushing process.
The second group of exercises deals with construction and transport machinery, their construction and operation. The exercises are aimed with the problems of interaction of tools with the soil. On the laboratory stand "soil channel", exercises will be presented to study the interaction of model tools of earth-moving construction machinery such as: loader bucket blade, excavator, scraper basket. The exercises will include the determination of cutting forces and work and the determina-tion of deformation mechanisms. The soil channel described in the paper allows students to fami-liarise themselves with the interaction of the driving system with the ground. The exercises will include determining the characteristics of the interaction of the crawler with the ground, investiga-ting changes in the tractive force of the machine as a function of slippage and the weight of the machine. Within the laboratory, exercises will be performed on a unique stand of a single-head hydraulic backhoe excavator, whose control and data acquisition system is fully automated. By performing the exercise on the single-head excavator, students will study selected methods for calculating cutting forces, the eff ect of excavator bucket shape and digging trajectory on cutting forces. The next stand is a rotating mechanism, where students can familiarise themselves with the properties of hydraulic drive systems using a hydraulic piston motor as an example, and the influence of the gain of individual controller components on system properties and speed control error. The script also includes a stand to learn about a typical PLC structure and the programme structure and programming method. Information on the theory of vibratory conveyor of granular materials is also presented in this study.

FOREWORD 9

1. DETERMINATION OF STRENGTH PROPERTIES OF GRANULAR AND BRITTLE MATERIALS 11

1.1. Theoretical introduction 11

1.1.1. Testing of soil and rock 11

1.1.2. Testing of uniaxial tensile strength 14

1.1.3. Uniaxial compression strength tests 15

1.1.4. Determination of strength parameters of soil and rock materials in triaxial compression tests 18

1.2. Description of the stands 20

1.2.1. Test stand for rock strength and elementary crushing processes – hydraulic press 20

1.2.2. Direct shear test 22

1.2.3. Triaxial compression apparatus 23

1.3. EXERCISE 1. Determination of uniaxial compressive and tensile strengths of rocks 24

1.3.1. Objective of the exercise 24

1.3.2. Course of the exercise 24

1.4. EXERCISE 2. Study on elementary crushing processes 24

1.4.1. Objective of the exercise 24

1.4.2. Course of the exercise 24

1.5. EXERCISE 3. Determination of Coulomb-Mohr characteristics – direct shear apparatus 25

1.5.1. Objective of the exercise 25

1.5.2. Course of the exercise 25

1.5.3. Elaboration of results 26

1.6. EXERCISE 4. Determination of Coulomb-Mohr characteristics – triaxial compression apparatus 27

1.6.1. Objective of the exercise 27

1.6.2. Course of the exercise 27

2. CRUSHING OF BRITTLE MATERIALS 29

2.1. Theoretical Introduction 29

2.1.1. General information 29

2.1.2. Classification of the crushing product 29

2.1.3. Terminology related to construction aggregates according to the standard [16] 31

2.2. Description of the laboratory stands 31

2.2.1. Laboratory jaw crusher 31

2.2.2. Laboratory impact crusher 35

2.2.3. Laboratory cone crusher 36

2.2.4. Sieve analysis shaker 37

2.3. EXERCISE 1. Rock crushing 38

2.3.1. Objective of the exercise 38

2.3.2. Course of the exercise 38

2.4. EXERCISE 2. Study of crushing processes in a model jaw crusher 40

2.4.1. Objective exercise 40

2.4.2. Course of the exercise 41

3. STUDIES ON THE MECHANICS OF THE CUTTING PROCESS OF BRITTLE MATERIALS 43

3.1. Theoretical introduction 43

3.1.1. General comments 43

3.1.2. Fundamentals of brittle material machining 43

3.1.3. Overview of tools and their working conditions using the example of an asphalt milling tool 46

3.2. Test stand overview 50

3.3. Measurement system 52

3.4. EXERCISE 1. Asphalt milling 53

3.4.1. Aim of the exercise 1 53

3.4.2. Conducting the exercise 53

3.4.3. Results analysis 54

3.5. EXERCISE 2. Brittle materials cutting 55

3.5.1. Aim of the exercise 2 55

3.5.2. Conducting the exercise 55

3.5.3. Results analysis – Cutting force in function of time and tool displacement 55

4. INTERACTION OF HEAVY MACHINERY WITH THE SOIL − SOIL CHANNEL 57

4.1. Theoretical introduction 57

4.1.1. General remarks 57

4.1.2. Track shoe types 57

4.1.3. Tractive force generated by flat shoes 58

4.1.4. Influence of anti-skid grousers on the tractive force 62

4.1.5. Track slip 62

4.2. Laboratory stand 63

4.2.1. Track-soil interaction of off-road undercarriages 63

4.2.2. Model tests of resistance to operation of working tools of earthmoving machines 64

4.3. EXERCISE 1. Track-soil interaction of off-road undercarriages 68

4.3.1. Aim of the exercise 68

4.3.2. Conducting the exercise 69

4.3.3. Results preparation 69

4.4. EXERCISE 2. Model tests of resistance to operation of working tools of earthmoving machines 69

4.4.1. Aim of the exercise 69

4.4.2. Conducting the exercise 70

4.4.3. Results preparation 70

5. VIBRATORY CONVEYORS 71

5.1. Theoretical introduction 71

5.1.1. General remarks 71

5.1.2. Single grain motion theory 74

5.2. EXERCISE 1. Vibrating conveyor 81

5.2.1. Aim of the exercice 81

5.2.2. Conducting the exercise 81

6. PLC PROGRAMMING 83

6.1. Introduction 83

6.1.1. PLC structure 86

6.2. The basic elements of sucosoft s40 programming language 87

6.2.1. Program structure 88

6.2.2. Declaration of real variable address 88

6.2.3. Program block 90

6.3. EXERCISE 1. PLC programming 93

6.3.1. Aim of the exercise 93

6.3.2. Conducting the exercise 94

7. SLEWING MECHANISM 97

7.1. Theoretical introduction 97

7.1.1. Functions analysis of the slewing mechanism equipped with a reductor 97

7.1.2. Control structure of the slewing mechanism operation 98

7.2. Testbench 101

7.2.1. General description of the testbench 101

7.2.2. Descriptions of hydraulic elements used in the testbench103

7.3. EXERCISE 1 106

7.3.1. Aim of the exercise 106

7.3.2. Conducting the exercice 106

8. ANALYSIS OF THE EXCAVATION PROCESS IN AN AUTOMATIC CYCLE OF A BACKHOE EXCAVATOR 109

8.1. Theoretical introduction 109

8.2. Laboratory stand 113

8.3. EXERCISE 1. Testing the influence of the shape of the working tool on the energy efficiency of the digging process 117

8.3.1. Aim of the exercise 117

8.3.2. Conducting the exercise 118

8.4. EXERCISE 2. Testing the impact of changing the cutting angle of the tool on the energy consumption of the excavating process 119

8.4.1. Aim of the exercise 119

8.4.2. Conducting the exercise 119

LITERATURE 121

  • Title: Laboratory of Construction Machinery
  • Author: Paweł Ciężkowski
  • ISBN: 978-83-8156-612-4, 9788381566124
  • Date of issue: 2024-02-28
  • Format: Ebook
  • Item ID: e_3tww
  • Publisher: Oficyna Wydawnicza Politechniki Warszawskiej