There are two kinds of cotton harvesters: pickers and strippers. While both collect cotton from the plant, pickers are selective in that they only pull open bolls of seed cotton.
For this to work, the cotton fiber must physically engage the revolving spindles of the harvester. This requires the spindles to be clean and in good working condition.
1. Spindle Design
The spindle, a motor-driven shaft that both positions and transmits power to a tool or holds a workpiece during machine tool operation, directly impacts efficiency, accuracy, and overall productivity. It is, therefore, critical that its design and performance meet the application requirements.
The design of a John Deere cotton picker spindle is complex and can vary greatly depending on the type of harvesting operation required. It is common for poorly adjusted and aligned spindle assemblies to lose 10 to 12 percent of picking efficiency.
In addition to the mechanical connection between the spindle and a main shaft, the system that transmits power to the spindle is also critical to its performance. For example, a poly V-belt system can be limited in its maximum speed by the ability of the pulleys to maintain contact and transmit torque without slipping. High rotational speeds tend to stretch and disengage the belts, causing the system to lose power transmission and vibration. Cogged belts eliminate this problem but have their own limitations.
Another important factor is the ability of the spindle to remove cotton from the plant. This is a function of the spindle hook teeth, which must be able to separate open bolls from bursts, unopened bolls, and other plant components that would interfere with cotton removal. In laboratory tests, a smaller straight spindle was more aggressive than a larger barbed spindle in removing cotton from the plant and preventing field stalk loss.
During the picking process, the cotton fibers wrap around the spindles and are pulled toward the center of the plant by the spinning action of the picker. The spindles then move around to a doffer, where they are rotated in the opposite direction, and the wrapped cotton is doffed from the spindles.
The lateral deflection of the spindle, bending stiffness, and other factors influence the quality of harvesting. The spindle must be designed for a particular speed range, which may require compromises in stiffness and bearing load ratings. For example, a spindle that requires the highest possible speed will be very heavy and will not have sufficient stiffness to operate at this speed without compromising bearing life.
2. Spindle Material
The quality of the materials used in a spindle can have a direct impact on its performance. The material of the bearing is of particular importance, as it will dictate how long the spindle lasts. The type of bearing also affects how much axial and radial load the spindle can handle. Angular contact ball bearings are commonly used in high-speed spindle designs because they offer precision and a high load-carrying capacity.
Another important consideration is the material of the spindle shaft itself. The shaft can be made from a variety of materials, including metals and plastics. In addition, the shaft can be shaped in different ways to form a whorl or other decorative element. The whorl can be affixed permanently, or it may be removable. The shape of the shaft can also play an important role in how quickly the spindle turns and how well it picks cotton.
In order for cotton picker machines to work, the mature cotton fiber must physically engage with and adhere to the revolving spindles. This is a laborious task that requires a large number of spindles. A high-quality spindle assembly is necessary to ensure that the cotton is picked as efficiently as possible.
If the spindle isn’t made of good quality material, it will eventually wear out and have to be replaced. This will increase machine downtime and reduce overall productivity. Therefore, finding a manufacturer that uses quality materials is essential.
When selecting a spindle manufacturer, it is important to look for a company that has a history of manufacturing high-quality products. It is also important to find out how the company produces its spindles and what kind of quality assurance measures it takes. A quality company will use a combination of advanced machining technology and a highly experienced workforce to ensure that the spindle is produced as accurately as possible.
Another consideration is the type of cooling system that a company uses to protect its spindles. A chiller or heat exchanger can help keep the spindle cool and prevent premature wear by reducing temperature fluctuations. A heat exchanger can also help keep the spindle clean by removing excess oil and contaminants.
3. Spindle Assembly
Keeping your cotton picker well-maintained and in good condition is one of the best ways to ensure that it continues to produce high yields and quality fiber. Among the many parts that are critical to this process, the cotton picker spindle assembly requires special cleaning and maintenance unique to its function. This is especially important if you wish to avoid expensive repair costs down the road.
The spindles used in a cotton picker are typically fabricated from special heat-treated steel and chrome plated to provide a hard, smooth surface. These spindles are then polished to remove any frost or rough spots that may cause the cotton to stick or fail to doff properly. This can be a time-consuming and costly procedure that is essential to the efficiency of the picker.
A typical spindle assembly includes a shaft with a drive gear and a rotatably mounted cone-shaped toothed picking end, an elongated tubular extension axially outward of the enlargement, and a shield that is mounted on, carried by and rotatable with the spindle and seals the enlargement. The shield has a skirt portion that completely surrounds the spindle and prevents direct engagement of the cotton plants or cotton bolls with the spindle extension. In addition, the skirt portion of the shield extends beyond locations where cotton would tend to build up on the bearing extremity of the spindle and thus prevents migration of the lubricant out of the bearing assembly into the cotton fibers.
In the present invention, the entire picking end of the spindle is coated with a very thin layer of ceramic material, such as silica chrome alumina oxide, which is substantially uniform over the entire surface of the picking end. The ceramic coating reduces friction and wear between the picking end of the spindle and the splines or teeth on the tip of the rotatably mounted cone-shaped toothed end and provides a very smooth and hard surface that resists damage, especially in sandy conditions.
In addition, the ceramic coating can be made with a harder surface than the chrome plating used on conventional picker spindles. This can greatly reduce the erosion rate of the splines or teeth and improve the longevity of the cotton picker spindle.
4. Spindle Calibration
The spindle assembly is an important part of the cotton picker that can influence harvest quality by affecting the machine’s overall performance. In order to ensure that the spindles are functioning properly, they should be kept in good condition and regularly cleaned. This helps prevent a buildup of plant juices, bark, dirt, and other debris that can cause the spindles to tangle together.
The tangled spindles can damage the cotton fibers and lead to a lower quality of lint. In order to avoid this, the cotton picker should be maintained on a regular basis, and the spindle assembly should be cleaned and degreased. This will help keep the cotton picker running smoothly and efficiently and increase the yield of the harvested crop.
In addition, the spindle should be calibrated on a regular basis. This will help to ensure that the spindles are producing a consistent torque. A calibration test is performed by placing a known amount of torque on one of the spindles and measuring it using a test instrument. The resulting torque reading is then used to calibrate the corresponding torque transducer on the testing assembly. The calibration process is repeated on each of the other spindles in the system to ensure that they are producing a similar torque.
During the calibration process, it is important to consider both time-invariant errors (manufacturing errors) and thermal errors. This is because a thermal error can have a significant impact on the accuracy of parallel kinematic machine tools.
Another factor that can affect the tangled spindles is the speed at which they rotate. Increasing the spindle rotational speed can reduce the number of tangled fibers and improve lint quality. However, if the rotational speed is increased too much it can cause short fiber and tiny knots in the lint.
To prevent this from happening, the spindle should be set to the appropriate speed for each individual cotton variety. The height control system of the cotton picker is a mechanical-electrical-hydraulic coupled system. The design of this system is challenging because there are many interactions between the mechanical and electrical parts. Therefore, it is essential to optimize both the mechanical structure and the control parameters of the height control system to improve the performance of the cotton picker.
