INTRODUCTION
Background and Rationale
Aims and Objectives
The design and development of the ISH, with an emphasis on blade development and testing, is reported in Chapters 3 and 4. This includes an analysis of the system (productivity, efficiency, safety and economics) in Chapters 5 and an analysis of the system (productivity, efficiency, safety and economy). ergonomic analysis (comparison of the cardiac circulatory system, metabolic system and strain on the skeletal and muscular system) between ISH and manual harvesting in chapters 6 and 7.
AN OVERVIEW OF HARVESTING SUGARCANE
- Sugarcane Harvesting Systems
- Manual Cutting
- Time study for the cut and bundle system
- Cutter performance
- Whole Stalk Harvesters
- Chopper Harvesters
- Comparison of Extraneous Matter and Losses between Systems
- Sugarcane Deterioration between Whole Stalk and Chopper Harvesters
- Summary of Systems
It is estimated that more than 80% of sugarcane in South Africa is burned before harvest (Smit et al, 2001). It is more difficult to harvest green cane because the cutter has to remove the canes compared to burnt cane as shown in Figure 2.1.
PART A: DESIGN OF THE ILLOVO SUGARCANE HARVESTER
LITERATURE REVIEW OF CUTTING FORCES AND BLADES
- Sugarcane Structure
- Cutting Forces
- Cutting Methods
- Cutting using curved and serrated blades
- Cutting with a countershear
- Sugarcane Chopper Harvester Base Cutter Blade Wear
- Summary
A typical cutting force versus time curve can be seen in figure 3.2 for a pure impact insert. The sharpness (LRE, figure 3.9) of a knife is the property that determines the magnitude of the force for initial penetration of the material.
DEVELOPMENT OF THE ILLOVO SUGARCANE HARVESTER
- Introduction
- Basic Blade Design from First Principles
- Brushcutter Adaptation and Sizing
- Force and power requirements
- Motor required
- Machine adaptations
- Design A: Results and discussion
- Design A: Limitations and recommendations
- Blade Design B
- Design B: Results and discussion
- Design B: Limitations and recommendations
- Blade Design C
- Design of connectors
- Design C: Results and discussion
- Design C: Limitations and recommendations
- Blade Design D
- Design D: Results and discussion
- Design D: Limitations and recommendations
- Failed Designs
- Conclusion
Tests showed that cutting only took place on half of the blade edge, as shown in Figure 4.10. This is due to the blade edge using fewer cuts to cut the cane stems.
PART B: SYSTEM AND ERGONOMIC ANALYSIS
SYSTEM ANALYSIS
- Introduction
- Aims and Objectives
- Methodology
- System Description
- Safety
- Measurements
- Results and Discussion
- System
- Performance
- System costs
- Machine durability
- Safety
- Conclusion
The machine had to be observed for its durability and estimate its life to determine the cost of the system. The cane required more sorting (Figure 5.7), but the increase in efficiency after the first line justified the system. The percentage distribution of the average costs for 2006 can be seen in figure 5.12 and the most probable distribution in figure 5.13.
The throttle rod, circled in blue in Figure 5.14, prevents the knife from getting close to the blade and keeps it away from the feet of the knife. The puller must not advance further than the throttles shown in Figure 5.15 and must assume that the cutter is not paying attention to where the blade is. It was the hauler's responsibility to move rocks out of the way if necessary.
The sorters must ensure that they do not work in front of the cutter or puller due to the risk of the blades breaking and being thrown forward. Special care must be taken when using System 1 due to the reciprocation of the cutter. Due to the development of the system and the reduction in downtime, ISH had a marked improvement in the 2006 season.
ERGONOMIC PRINCIPLES IN HARVESTING SUGARCANE
- Background
- Measuring Energy Expenditure
- Estimating energy expenditure from oxygen uptake
- Relationship between V 0 2 and heart rate
- Perceived Exertion
- Occupational Low Back Disorder (LBD) in the Work Place
- Lumber Motion Monitor (LMM) risk model
- Analysis of the LMM risk model
- Body mass loss and fluid intake
- Heart rate and energy expenditure
- Improving Sugarcane Cutters Productivity
- Conclusion
Direct calorimetry measures the body's heat production which is correlated with the energy expended, while indirect calorimetry measures oxygen consumption which is directly related to energy expenditure (McArdle et al, 2001). It is possible to determine the volume of oxygen consumption (VO2) using a portable ergospirometer which is an indirect method of calorimetry (McArdle et al, 2001). To obtain the energy consumption (EE) in kJ per min, the volume of oxygen (L.min"1) consumed is multiplied by the constant 20.1 as shown in Equation 6.1.
This is then multiplied by the total time the task is done to obtain the total energy consumption. By measuring the heart rate it is therefore possible to predict the oxygen intake and therefore the energy consumption of a person. Measuring only the energy expenditure does not give a true reflection of the demands of the task (Borg, 1970).
The objective was to determine body weight loss and energy consumption among sugarcane cutters and stackers. However, the unacceptable imbalance between workers' nutritional intake and the energy expenditure required to perform specific tasks is of great concern. Alba and Escober (1974) and Orane (1970) identified the following sugarcane cutting methods that, if used, could increase overall productivity: grasping and cutting three or more stalks simultaneously,. when pouring, be careful not to let the tops fall into the cut sugar cane or bundles. the shortest possible distance from the beam to the uncut sugar cane. throwing cut sugarcane into the wind without turning to look at the row,. work during the coldest hours of the day, i.e.
ERGONOMIC STUDY
- Methodology
- Energy expenditure
- Perceived exertion and body discomfort
- LMM risk model
- Results and Discussion
- Energy expenditure
- Body mass changes
- Perceived exertion and body discomfort
- LMM risk model
- Conclusion
Using equation 6.1, EE was determined and multiplied by time spent performing various tasks. To make a comparison, the manual cutting action was compared with the Illovo harvesting method. Due to the unrealistic results obtained for MIO, a comparison was made with Ml for ISH.
It involved an average weight loss of 4% of body weight with manual cutting and 1.4% with the Illovo harvester. The average fluid intake for manual harvesting was 2.2 liters and for the Illovo harvester 0.5 liters (Appendix D). For the Illovo harvester (blue bar), it falls into the low-risk region with a probability of about 12%.
The results suggest that the Illovo cutter requires less energy per tonne and proves to be more energy efficient compared to the manual harvesting method. The RPE was lower for the Illovo harvester, but there was a significantly lower weight loss compared to the manual system. The LMM risk model shows that the Illovo cutter falls into the Low-risk group compared to the High-risk group for manual harvesting.
DISCUSSION, CONCLUSION AND RECOMMENDATIONS
- Discussion and Conclusions
- Recommendations for Further Research
The machine could not last the whole season mainly due to the bending of the drive pipe and shaft. Operating costs were approximately 15.84 Rt~1 and competitive with conventional manual harvesting. But more needs to be done to reduce downtime, improve management, implement a change management system, and convince workers and farmers of the benefits of the system.
The data suggests that Illova's sugar cane harvester uses less energy per ton and has been found to be more energy efficient compared to the current manual harvesting method. However, this may change with improvements to the harvester (making the blade and machine . lighter) and more training for workers (using proper harvesting techniques). The LMM risk model showed that the Illovo harvester fell into the low-risk occupational group compared to the high-risk group for manual harvesting.
The connections must be adjusted to reduce the size of the protruding bolt heads that cause damage to the cane and excessive debris. One way is to implement the task system and reduce the double wielding of the cane. This will probably reduce the energy consumption as the body will be more accustomed to the operation.
The relationship between spinal load factors and the probability of high risk of occupational low back disorder. Validity of using heart rate in estimating oxygen consumption during static and combined static/dynamic exercise. The role of dynamic three-dimensional trunk motion in work-related low back disorders: effects of workplace factors, trunk position, and trunk motion characteristics on injury risk.
The effectiveness of commonly used light assessment methods to identify industrial jobs associated with increased risk of low back disorders. The biomechanics of low back injury: implications for current practice in industry and the clinic Journal of Biomechanics. A comparison of risk assessment of single and combination manual handling tasks: discomfort, rating of perceived exertion and heart rate measures.
APPENDIX A
APPENDIX B
APPENDIX C
CI. DEVELOPMENT OF THE SUGARCANE TOPPER
The head is a standard 40mm head with serrated alternating teeth as shown in Figure CI.2. This is more than enough to cut sugar cane tops and they decided to give it a try. The measuring tooth was ground to allow a better bite to prevent the rod from being pushed to one side (Figure CI.3).
This was attached to the chainsaw head seen in Figure CI.4 and the gap between the teeth was originally 50mm but testing showed it needed to be larger. The chainsaw head cutting method can be seen in Figure CI.5 and cuts the tips effectively and quickly shown in Figure CI.6. The problems with the system were that the tops did not fall to the ground, but were caught in the bench and cane (Figure CI.7).
This results in the buds being loaded into the stack, reducing purity and not being accepted by the mill. The head with the down-sharpened measuring tooth cuts the buds effectively, but once the buds are cut, they are not placed in an order that allows for subsequent stacking of the stick without adding large amounts of bud. Further recommendations are that an implement should be designed that pushes or blows away the tops of the row of cane and drops them into the intermediate row.
APPENDIX D
Movement maximum left deflection maximum right deflection maximum lateral extent. maximum extension maximum flexion maximum sagittal extent. maximum left turn maximum right turn maximum turn angle. average lateral velocity maximum lateral velocity. average sagittal velocity maximum sagittal velocity. average yaw rate maximum yaw rate maximum lateral acceleration maximum sagittal acceleration. degrees) (degrees) (degrees) (degrees) (degrees) (degrees) (degrees) (degrees) (degrees) (degrees/sec) (degrees/sec) (degrees/sec) (degrees/sec) (degrees/sec ) ) (degrees/s) (degrees/s2) (degrees/s2) (degrees/s2).
APPENDIX E
Not using the right people to implement the change: The people with the highest position in the industry must show that this change is important. It is often called 'the change roller coaster' because of the ups and downs of the workers caused by the change program. This is the final stage and is the process where the idea is anchored to ensure that the benefits of the change are not lost or to prevent the company from slipping back into its old habits and ways of working.
According to Bourne and Bourne (2002), the three ways to refreeze an organization are by anchoring the change in the organization's structure, using a recognition and reward system or changing the organization's culture. Anchoring the change in the organization's structure is very difficult but immediately shows where the problems and focus areas should be. It is necessary to ensure that the incentives and rewards are in line with the change.
Adapting the structures and incentives is the first step and the change in culture comes from senior management. Once the change is implemented, an ongoing assessment must take place to ensure that the change is a success. Obstacles must not be allowed to prevent the change from taking place and thereby creating a lasting solution.
